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CHAPTER 16 Aortic Aneurysms

Prognosis 2 cm, whereas others recommend 3 cm. The risk of symp-
toms is approximately 25% at 1 year and 67% at 5 years.
The greatest risks associated with TAA are aneurysmal Symptomatic aneurysms require repair. The most com-
expansion and rupture. Survival rates range from 39% mon surgical repair includes ligation at the proximal and
to 87% at 1 year and 13% to 46% at 5 years. The aneu- distal ends of the aneurysm and a saphenous vein bypass.
rysm diameter at diagnosis is predictive of rupture. In Thrombolysis may be used occasionally to clear the runoff
one study, patients with a TAA diameter 5 cm or larger vessels and improve graft patency.
had a 3-year survival rate of 60%; those with an aneurysm
smaller than 5 cm had a 90% 3-year survival rate. The op- • Popliteal artery aneurysms occur in approximately 3%-
timal diameter at which a TAA should be repaired is not 10% of patients with AAA
well defined. Most studies suggest repair of an ascending
aortic aneurysm at a diameter of 5.5 to 6.0 cm. For pa- • More than 50% of popliteal artery aneurysms occur bi-
tients with Marfan syndrome, repair is recommended at laterally
a diameter of 4.5 to 5.0 cm. For patients with descending
TAAs, repair should be considered at a diameter of 6.5 to • Popliteal artery aneurysms may rupture, although rup-
7.0 cm. ture is rare

• Dissection precedes aneurysm dilatation in 15% to 20% • The most common symptoms at presentation are
of patients with TAA ischemia due to distal embolism, popliteal artery throm-
bosis, occlusion, and peroneal nerve compression
• The optimal diameter for repair of TAA is not well de-
fined • The threshold for repair of asymptomatic aneurysms is
• For an ascending aortic aneurysm: 5.5-6.0 cm controversial (2 cm vs 3 cm)
• For patients with Marfan syndrome: 4.5-5.0 cm
• For a descending TAA: 6.5-7.0 cm Questions

Popliteal Artery Aneurysm 1. Which of the following is the most common complica-
tion of a popliteal artery aneurysm?
Peripheral artery aneurysms most commonly are located a. Rupture
in the popliteal artery. The incidence of popliteal artery b. Thrombosis or embolism with limb ischemia
aneurysms is 0.1% to 0.3%. They occur in approximately c. Popliteal vein thrombosis
3% to 10% of patients with AAA. As with AAA, most pa- d. Peroneal nerve palsy
tients are 65 years or older and are predominantly men.
These aneurysms occur bilaterally for more than 50% of 2. Which of the following mechanisms accounts for most
patients. Older age and hypertension are associated with AAAs?
aneurysm expansion. Popliteal aneurysms may be saccu- a. Inherited disorder of fibrillin synthesis
lar or fusiform. Saccular aneurysms may cause symptoms b. Increased concentration of MMPs
of compression, whereas fusiform aneurysms are more c. Altered shear stress
likely to cause distal embolization or to thrombose. Both d. Infiltration of the vascular wall by lipid-laden macro-
types may rupture, although rupture is rare. phages

The most common symptoms at presentation are 3. A 72-year-old woman with an AAA has been monitored
ischemia (resulting from distal embolization), popliteal with yearly abdominal ultrasonography for 5 years. The
artery thrombosis, and peroneal nerve compression. Ve- maximal diameters measured were 3.7 cm at 1 year, 3.7
nous compression may occur if the aneurysm is larger cm at 2 years, 3.9 cm at 3 years, 4.0 cm at 4 years, and 5.0
than 2 cm. Popliteal artery aneurysm can be diagnosed cm at 5 years. What do you now recommend?
by palpation in more than 90% of cases (if performed by a. Abdominal ultrasonography in 6 months
an experienced clinician). However, approximately 75% b. β-Blockers
of popliteal aneurysms will be undetected by general c. Doxycycline
practitioners, even in symptomatic patients. Imaging of d. Aneurysm repair
the popliteal artery should be performed for confirmation;
duplex ultrasonography is 100% sensitive for the diagno- 4. Which of the following factors is not associated with
sis of a popliteal aneurysm. AAAs?
a. Male sex
The threshold for repair of asymptomatic aneurysms is b. Advancing age
controversial. Some suggest repair when the diameter is c. Cigarette smoking
d. Diagnosis of diabetes mellitus

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Vascular Medicine and Endovascular Interventions

5. CTA confirmed a 5.0-cm fusiform aneurysm of the 41 cases. Arthritis Rheum. 1994;37:1539-47. Erratum in: Arthri-
descending thoracic aorta in a 74-year-old man. He is tis Rheum. 1995;38:290.
asymptomatic. Which of the following management EVAR Trial Participants. Endovascular aneurysm repair and
options is most appropriate? outcome in patients unfit for open repair of abdominal aortic
a. Imaging study (magnetic resonance angiography or aneurysm (EVAR trial 2): randomised controlled trial. Lancet.
CTA) in 6 months to assess the size of the TAA 2005;365:2187-92.
b. Administration of doxycycline to decrease the risk of Isselbacher EM. Thoracic and abdominal aortic aneurysms. Cir-
TAA expansion culation. 2005;111:816-28.
c. Endovascular fenestration of the thoracic aorta Kerr GS, Hallahan CW, Giordano J, et al. Takayasu arteritis. Ann
d. Surgical repair of the TAA Intern Med. 1994;120:919-29.
Lederle FA, Johnson GR, Wilson SE, Aneurysm Detection and
Suggested Readings Management Veterans Affairs Cooperative Study Investiga-
tors. Abdominal aortic aneurysm in women. J Vasc Surg.
Ailawadi G, Eliason JL, Upchurch GR Jr. Current concepts in 2001;34:122-6.
the pathogenesis of abdominal aortic aneurysm. J Vasc Surg. Lederle FA, Johnson GR, Wilson SE, et al, Aneurysm Detection
2003;38:584-8. and Management (ADAM) Veterans Affairs Cooperative
Study Group. Prevalence and associations of abdominal aor-
American Heart Association. Heart disease and stroke statistics: tic aneurysm detected through screening. Ann Intern Med.
2004 update. Dallas (TX): American Heart Association; 2003. 1997;126:441-9.
Lederle FA, Johnson GR, Wilson SE, et al, Aneurysm Detection
Ashton HA, Buxton MJ, Day NE, et al, Multicentre Aneurysm and Management Veterans Affairs Cooperative Study Inves-
Screening Study Group. The Multicentre Aneurysm Screening tigators. The aneurysm detection and management study
Study (MASS) into the effect of abdominal aortic aneurysm screening program: validation cohort and final results. Arch
screening on mortality in men: a randomised controlled trial. Intern Med. 2000;160:1425-30.
Lancet. 2002;360:1531-9. Lederle FA, Johnson GR, Wilson SE, et al, Veterans Affairs Coop-
erative Study #417 Investigators. Rupture rate of large abdom-
Baxter BT, Pearce WH, Waltke EA, et al. Prolonged administra- inal aortic aneurysms in patients refusing or unfit for elective
tion of doxycycline in patients with small asymptomatic ab- repair. JAMA. 2002;287:2968-72.
dominal aortic aneurysms: report of a prospective (Phase II) Lederle FA, Wilson SE, Johnson GR, et al, Aneurysm Detection
multicenter study. J Vasc Surg. 2002;36:1-12. and Management Veterans Affairs Cooperative Study Group.
Immediate repair compared with surveillance of small abdom-
Blankensteijn JD, de Jong SE, Prinssen M, et al, Dutch Randomized inal aortic aneurysms. N Engl J Med. 2002;346:1437-44.
Endovascular Aneurysm Management (DREAM) Trial Group. Panneton JM, Hollier LH. Nondissecting thoracoabdominal aor-
Two-year outcomes after conventional or endovascular repair tic aneurysms: Part I. Ann Vasc Surg. 1995;9:503-14.
of abdominal aortic aneurysms. N Engl J Med. 2005;352:2398- Prall AK, Longo GM, Mayhan WG, et al. Doxycycline in patients
405. with abdominal aortic aneurysms and in mice: comparison of
serum levels and effect on aneurysm growth in mice. J Vasc
Brady AR, Fowkes FG, Greenhalgh RM, et al, UK Small Aneu- Surg. 2002;35:923-9.
rysm Trial Participants. Risk factors for postoperative death Prinssen M, Verhoeven EL, Buth J, et al, Dutch Randomized En-
following elective surgical repair of abdominal aortic aneu- dovascular Aneurysm Management (DREAM) Trial Group.
rysm: results from the UK Small Aneurysm Trial. Br J Surg. A randomized trial comparing conventional and endovas-
2000;87:742-9. cular repair of abdominal aortic aneurysms. N Engl J Med.
2004;351:1607-18.
Cole CW, Barber GG, Bouchard AG, et al. Abdominal aortic an- Propranolol Aneurysm Trial Investigators. Propranolol for small
eurysm: consequences of a positive family history. Can J Surg. abdominal aortic aneurysms: results of a randomized trial. J
1989;32:117-20. Vasc Surg. 2002;35:72-9.
Shores J, Berger KR, Murphy EA, et al. Progression of aortic dila-
Dapunt OE, Galla JD, Sadeghi AM, et al. The natural his- tation and the benefit of long-term beta-adrenergic blockade in
tory of thoracic aortic aneurysms. J Thorac Cardiovasc Surg. Marfan’s syndrome. N Engl J Med. 1994;330:1335-41.
1994;107:1323-32. Singh K, Bonaa KH, Jacobsen BK, et al. Prevalence of and risk
factors for abdominal aortic aneurysms in a population-based
Darling RC, Messina CR, Brewster DC, et al. Autopsy study of study: The Tromso Study. Am J Epidemiol. 2001;154:236-44.
unoperated abdominal aortic aneurysms: the case for early Steyerberg EW, Kievit J, de Mol Van Otterloo JC, et al. Periopera-
resection. Circulation. 1977;56 Suppl:II161-4. tive mortality of elective abdominal aortic aneurysm surgery:
a clinical prediction rule based on literature and individual
Dawson I, Sie R, van Baalen JM, et al. Asymptomatic popliteal patient data. Arch Intern Med. 1995;155:1998-2004.
aneurysm: elective operation versus conservative follow-up. Szekanecz Z, Shah MR, Harlow LA, et al. Interleukin-8 and
Br J Surg. 1994;81:1504-7. tumor necrosis factor-alpha are involved in human aortic en-

Downing R, Grimley RP, Ashton F, et al. Problems in diagnosis of
popliteal aneurysms. J R Soc Med. 1985;78:440-4.

Elefteriades JA. Natural history of thoracic aortic aneurysms:
indications for surgery, and surgical versus nonsurgical risks.
Ann Thorac Surg. 2002;74:S1877-80.

Evans JM, Bowles CA, Bjornsson J, et al. Thoracic aortic aneu-
rysm and rupture in giant cell arteritis: a descriptive study of

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CHAPTER 16 Aortic Aneurysms

dothelial cell migration: the possible role of these cytokines in for randomised controlled trial of early elective surgery or
human aortic aneurysmal blood vessel growth. Pathobiology. ultrasonographic surveillance for small abdominal aortic an-
1994;62:134-9. eurysms. Lancet. 1998;352:1649-55.
Tang JL, Morris JK, Wald NJ, et al. Mortality in relation to tar United Kingdom Small Aneurysm Trial Participants. Long-
yield of cigarettes: a prospective study of four cohorts. BMJ. term outcomes of immediate repair compared with surveil-
1995;311:1530-3. lance of small abdominal aortic aneurysms. N Engl J Med.
The UK Small Aneurysm Trial Participants. Mortality results 2002;346:1445-52.

193

17 Aortic Dissection and Dissection-Like
Syndromes

Joshua A. Beckman, MD, MS

Acute aortic syndromes are among the most serious of clear, but the newly recognized syndrome of IMH may
vascular complications; they require physician suspicion provide some insight.
for diagnosis, use of specific medical and surgical thera-
pies, and are fatal if untreated for too long. The disease In an IMH, the vasa vasorum ruptures and hemor-
course of aortic dissection can be dire; the mortality rate rhages into the subintimal space, separating the layers
is 1% per hour during the first day, 50% by 1 week, and of the vessel wall. If the process is confined to the aortic
90% by 3 months. This chapter describes aortic dissection wall, it is considered an IMH. However, if the pressure
and dissection-like syndromes, including intramural he- within the wall is sufficiently high, overt dissection may
matoma (IMH), penetrating atherosclerotic ulcer (PAU), develop. The relative proportions of aortic dissection and
and carotid artery dissection. IMH without overt dissection are poorly defined, but in
autopsy series of aortic dissection, up to 13% of the de-
Aortic Dissection cedents had no identifiable tear. A rarer mechanism of aor-
tic dissection is a PAU. Large atherosclerotic ulcers may
Epidemiology disrupt the internal elastic lamina of the aorta and cause
a local hematoma, aortic pseudoaneurysm, aortic dissec-
Although the estimated incidence of aortic dissection in tion, or aortic rupture.
the United States has decreased over the past 30 years,
approximately 2,000 new cases still occur each year. Au- Classification
topsy studies have suggested an annual incidence of 5 to
10 cases per million, whereas among whites in Minnesota, Two classification schemes—the DeBakey and Stanford
the rate may be as high as 27 cases per million. Blacks have systems—have been used to define aortic dissection. Most
a higher prevalence of aortic dissection, possibly because physicians use the Stanford system, which categorizes
of a greater incidence of hypertension. The precise num- dissections as type A or type B, depending on whether the
bers are difficult to determine because up to one-third of ascending aorta is involved. Type A dissection involves
patients with an acute aortic dissection die before receiv- the ascending aorta, regardless of the location of the aortic
ing medical care. tear, whereas type B dissection is limited to the descend-
ing aorta. Dissections with retrograde extension to the
Pathogenesis ascending aorta should be regarded as a dissection that
begins in the ascending aorta.
An intimal tear is the classic initial event of an aortic dis-
section. After the intima is exposed to pulsating blood at • The Stanford system classifies dissection as type A (in-
high pressure, mural separation ensues and is propagated volving the ascending aorta) or type B (involving the
by ventricular systole. The cause of the initial tear is un- descending aorta)

© 2007 Society for Vascular Medicine and Biology • Type A dissections have a very high rate of mortality
(1% per hour during the first day) if medical therapy is
not effective

• The diagnosis of a type A dissection should prompt ur-
gent surgical consultation and repair

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CHAPTER 17 Aortic Dissection and Dissection-Like Syndromes

The Stanford system is useful because of its inherent prog- most common are Marfan syndrome and Ehlers-Danlos
nostic value and because classification aids in manage- syndrome. Marfan syndrome is the most common inher-
ment decisions. Type A dissections have a high mortality ited connective tissue disorder, with an incidence of ap-
rate—up to 1% per hour during the first day if they are not proximately 1 in 7,000 persons. The disease is attributable
ameliorated considerably with medical therapy. Urgent to many different fibrillin-1 gene mutations with variable
surgical consultation and repair is therefore indicated for penetrance. Disease manifestations include ectopia lentis,
type A dissections. A 6-year series of patients treated with ligamentous redundancy, mitral valve regurgitation, and
or without surgery showed a mortality rate decrease of ascending aortic aneurysm. In the aortic wall, the effects of
more than 50% for the surgically treated group. dedifferentiation of vascular smooth muscle cells, abnor-
mal structural tissue, and increased expression of metallo-
In contrast, most patients with type B dissections can proteases combine to weaken the aortic wall and increase
be treated medically. The mortality rate in a recent series the likelihood of dissection.
of type B dissections that were treated medically was
approximately 10%. Surgery for type B dissections typi- Ehlers-Danlos syndrome is a rare congenital defect of
cally is reserved for patients with evidence of visceral and type III collagen production. The most common mani-
major organ compromise, limb ischemia, refractory pain, festations include acrogeria, facial features that include
secondary hypertension, or a combination of these symp- a beaked nose and small jaw, thin skin, easy bruising,
toms. The risks of mortality and paraplegia are increased and vascular rupture. Pathologic examination shows
for patients who require surgery. Dissection may weaken fragmented internal elastic lamina and deposition of gly-
the wall of the aorta, and therefore patients treated medi- cosaminoglycans in the media of large vessels. In a study
cally are at long-term risk for aneurysm formation. For of 199 patients with the vascular type of Ehlers-Danlos
these patients, aortic size should be monitored regularly, syndrome (type IV), 80% had a vascular or viscus rupture
and they should undergo aortic aneurysm repair if they by age 40 years.
meet the routine repair criteria (discussed in detail in
Chapter 16). Risk factors for aortic enlargement include • Hypertension is the risk factor most commonly associ-
an initial size of 4 cm or larger and a patent false lumen. ated with development of aortic dissection

• The mortality rate in a recent series of type B dissections • Patients with congenital structural abnormalities of the
treated medically was ≈10% aortic wall or with congenital valve disease have higher
rates of aortic dissection at younger ages
• Surgery typically is reserved for patients with evidence
of visceral and major organ compromise, limb ischemia, • Hereditary connective tissue disorders (Marfan syn-
and secondary hypertension drome and Ehlers-Danlos syndrome) predispose pa-
tients to aortic dissection
• Patients should undergo aortic aneurysm repair if they
meet routine repair criteria Presentation

Risk Factors Nearly all patients with aortic dissection present with pain
or loss of consciousness. Pain occurs in more than 90%
Hypertension is the risk factor most commonly associated of patients with type A and type B dissections. The pain
with development of aortic dissection. In several large se- usually is described as sharp or tearing with a sudden
ries, hypertension was present in 70% of patients. Aortic onset and may change location. Anterior chest and throat
dissection also is common in older patients; in the larg- pain is more commonly associated with a type A dissec-
est cohort of patients with aortic dissection, the mean age tion, whereas pain exclusively in the back signals a type B
was 63 years. Patients with type B dissections generally dissection. The pain of aortic dissection may be confused
are older than those with type A dissections. Men are two with that of myocardial infarction or pneumothorax if it is
times more likely than women to have aortic dissection. in the chest, or it may be mistaken as pancreatitis or renal
Other important precipitants of aortic dissection include colic if it affects the back or abdomen. Patients who present
iatrogenic causes (e.g., catheterization, cardiac surgery), with neurologic symptoms (e.g., stroke or paraplegia) or
aortic valve disease, and pregnancy. with throat or neck pain are likely to have arch vessel com-
promise, extension of the dissection into cerebral vessels,
Although patients with congenital structural abnormal- or a combination of the two. Loss of consciousness may re-
ities of the aortic wall or with congenital valve disease (bi- sult from neurologic involvement or severe hemodynamic
cuspid aortic valve or unicommissural valves) are a small embarrassment.
portion of the population with aortic dissection, they have
much higher rates of aortic dissection at younger ages than • Pain occurs in more than 90% of patients with type A
in age-matched controls. Hereditary connective tissue and type B dissections
disorders predispose patients to aortic dissection; the two

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Vascular Medicine and Endovascular Interventions

Physical findings of aortic dissection may include hypo- pharmacologic agent. Calcium-channel antagonists and
tension or shock, pulse deficits, congestive heart failure, angiotensin-converting enzyme inhibitors also may be
and aortic valvular insufficiency. Each of these findings used. For patients with low arterial perfusion pressure,
is associated with an increased risk of mortality. Less esmolol may be used to rapidly titrate blood pressure
common physical findings include superior vena cava and heart rate. Hypotension may be due to compromise
syndrome, hematemesis, hemoptysis, and Horner syn- of limb perfusion after arterial dissection or development
drome. Laboratory evaluations, chest radiography, and of an aortic dissection flap. If one arm has a higher blood
electrocardiography usually have limited value in the di- pressure than the other, the medication should be titrated
agnosis of an aortic dissection. No specific blood tests are to the higher-pressure limb, especially if a pulse variation
currently useful for diagnosis. Elevated creatinine levels, between the limbs is noted.
which signal new renal failure, are a potent predictor of
death and branch vessel involvement. • For patients with an aortic dissection, two therapeutic
modalities are recommended
Methods of Diagnosis • Pain control
• Blood pressure reduction
Computed tomography (CT), transesophageal echocardi-
ography (TEE), and magnetic resonance imaging (MRI) • Therapy to reduce blood pressure:
provide greater than 90% sensitivity and specificity for the • Intravenous sodium nitroprusside (a direct arterial
diagnosis of acute aortic dissection. CT and TEE are often vasodilator)
preferred in urgent situations because they tend to be • β-blockers (negative inotropic agents) to decrease the
readily available. An MRI examination typically requires force of ventricular contraction
more time and involves less patient supervision; both are
inappropriate for unstable patients. The choice between Presurgical management of patients with pericardial
CT and TEE should be made on the basis of local expertise tamponade and type A dissection is poorly defined. In a
and availability—the most rapid and most accurate test is study of 10 patients with aortic dissection, the mortality
the best. In certain settings, one test may be preferred over rate was high (60%), and pericardiocentesis seemed to
the other. For a patient with aortic insufficiency or pos- worsen outcomes. Most physicians would recommend
sible cardiac tamponade, TEE provides information about emergent surgery instead of coronary catheterization. In
valve function and movement of the heart walls. addition, catheterization does not decrease mortality in
these patients.
Occasionally, despite a strong clinical suspicion, a diag-
nostic test will not show a dissection. Several possibilities To minimize the mortality rate, patients with a type A
might account for the negative finding. First, TEE can- aortic dissection require emergent surgery. Recent series
not image the arch and distal ascending aorta because of have shown a 50% mortality rate for patients who do not
the interposed trachea. Second, less common aortic syn- have surgical repair, compared with a 10% to 30% mortal-
dromes such as IMH or intimal tear without hematoma ity rate for patients who do. The most common causes of
may not be detected with this imaging method. If a high death include cardiac tamponade, circulatory failure, aor-
index of suspicion exists, a second, complementary mo- tic rupture, stroke, and visceral ischemia. Older patients
dality should be used. and women are less likely to be referred for surgery than
younger and male patients. The factors most associated
Management with death include age older than 70 years, abrupt onset of
chest pain, hypotension or shock, kidney failure, a pulse
Patients with a diagnosis of aortic dissection or a high deficit, and abnormal electrocardiography findings at
clinical suspicion for dissection require rapid initiation of presentation. The number of pulse deficits has prognostic
medical therapy, namely pain control and blood pressure value: patients with 2 or more pulse deficits have a 5-day
reduction. Narcotic analgesia should be instituted to re- mortality rate of nearly 50%. Although not in common
duce pain. A direct arterial vasodilator to decrease blood clinical use, endovascular repair techniques are being
pressure and a negative inotropic agent to decrease the developed to treat this disease. The most common treat-
force of ventricular contraction are recommended. These ments are surgical repair of the aorta or replacement of the
medications should be provided intravenously to ensure aortic root and aortic valve.
absorption and facilitate rapid adjustment.
• Patients with a diagnosis of type A aortic dissection re-
The most commonly recommended vasodilator is in- quire emergent surgery
travenous sodium nitroprusside; β-blockers are used
most commonly to decrease the force of ventricular con- • The most common causes of death:
traction. Labetalol combines both properties in a single • Cardiac tamponade
• Circulatory failure

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CHAPTER 17 Aortic Dissection and Dissection-Like Syndromes

• Aortic rupture subintimal space occurs in aortic dissection, only intra-
• Stroke mural hemorrhage with circumferential or longitudinal
• Visceral ischemia spread is seen in an IMH. Although definitive proof is
lacking, vasa vasorum rupture currently is the accepted
Medical therapy is the main treatment modality for mechanism for IMH formation. Increasing pressure in the
type B dissections. Patients without evidence of visceral aortic wall may cause an intimal tear and a classic aortic
compromise, claudication, progression of the dissection, dissection. Some investigators have posited that invisible
uncontrolled hypertension, unremitting pain, or Marfan microtears are involved in the formation of an IMH.
syndrome may be managed medically and have a 30-day
mortality rate of about 10%. Limb ischemia, major organ The presentation of IMH is similar to that of a classic
ischemia, or renal failure increases the risk of mortality aortic dissection. Abrupt onset of pain is most common,
to 20% by day 2. Some series have reported mortality and pain in the chest and back occurs for both. Patients
rates exceeding 70% for renal and mesenteric ischemia. with IMH tend to be older than patients with classic aortic
Percutaneous interventions to treat type B dissection dissection. IMH is more likely to occur in the abdominal
are being developed. Abdominal aortic dissections are aorta, and involvement of the aortic valve is less common.
treated with placement of stents or balloon fenestration The disease course of an IMH typically becomes obvious
of the dissection flap (particularly if the patient is a poor soon after diagnosis—showing either regression with he-
surgical candidate) to restore compromised circulation in matoma resorption or progression to classic dissection,
a major organ or limb. By maintaining flow through the aneurysm formation, or rupture. Factors that portend a
false lumen, fenestration can increase the long-term risk of higher risk of morbidity and mortality include involve-
aneurysm formation and rupture. Freedom from death or ment of the ascending aorta, aortic diameter exceeding 5
recurrent symptoms is as high as 86% at 14 months for pa- cm, increasing thickness of the hemorrhage on serial ra-
tients undergoing the percutaneous procedure. Endovas- diologic evaluations, and presence of ulceration.
cular repair also has been used to treat type B dissections,
and experience with this procedure is increasing. Overall, the mortality rate for IMH is similar to that for
classic dissection. As in classic dissection, the IMH loca-
Follow-Up tion greatly influences prognosis and management. Using
the Stanford classification system, a type A IMH is more
For patients with aortic dissection who receive appropri- likely to progress than a type B IMH. One study showed
ate treatment, survival rates are approximately 90%, 80%, that patients with an IMH had a 30-day mortality rate of
and 50% at 1, 5, and 10 years, respectively. Death after 20% and a 5-year mortality rate of 57%. Patients with a
the index operation typically occurs within 2 years of the type A IMH had an early mortality rate of 8% with surgi-
event. The most common causes of death are cardiovas- cal therapy and 55% with medical therapy. Patients with a
cular disease or aortic rupture. As many as one-fourth of type B IMH who underwent surgery had double the 1-year
patients require reoperation within 10 years, most com- mortality risk (50%) of those treated medically (23.5%).
monly because of aneurysmal expansion of the aorta, Risk factors for progression of an IMH (e.g., development
which prompts strict radiographic follow-up. Most physi- of dissection, longitudinal progression of the IMH, or ero-
cians recommend follow-up with CT or MRI at 3, 6, and 12 sion of the aorta) include the presence of a large PAU on
months after the index operation and yearly examinations the IMH, increasing pleural effusion, a symptomatic PAU,
thereafter to monitor aortic expansion. Candidates for an- and a type A location. Long-term outcomes are adversely
eurysm repair after dissection must meet the same criteria affected by Marfan syndrome, younger age, and lack of
as those having repair of aneurysms without dissection. β-adrenergic blockade.
Initial aortic diameter greater than 4 cm and a patent false
lumen are predictive of more rapid expansion and the re- The modalities used to diagnose IMH are the same
quirement for repair. as those used for aortic dissection. Typically, IMH is de-
picted radiographically as a hemorrhage contained within
Dissection-Like Syndromes the vessel wall which does not enter the lumen. After the
condition is diagnosed, IMH treatment is similar to that
Intramural Hematoma of aortic dissection. Medical therapy that targets blood
pressure and ventricular contraction reduction should be
IMH is the most common variant of aortic dissection, affect- instituted. If it is identified during the evaluation of sug-
ing 5% to 10% of patients with an acute aortic syndrome. gestive symptoms, a type A IMH should be repaired surgi-
Whereas an obvious intimal tear between the lumen and cally and a type B IMH should be managed medically. The
management of asymptomatic IMH discovered inciden-
tally is unclear and should be tailored to each patient.

• IMH is the most common aortic dissection variant

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Vascular Medicine and Endovascular Interventions

• IMH occurs in 5%-10% of patients with an acute aortic Most patients with carotid dissection present with uni-
syndrome lateral facial or neck pain and a partial Horner syndrome
(miosis, ptosis, but not enophthalmos) from a disruption
• The mortality rate for patients with an IMH is similar to of the sympathetic nerve fibers that course along the carot-
that for patients with a classic aortic dissection id artery. Cerebral or retinal ischemia may develop hours
or days later in 50% to 95% of patients. Although few pa-
• A type A IMH should be repaired surgically, but a type tients have all three manifestations, most have two. Cra-
B IMH should be managed medically nial nerve abnormalities are identified in approximately
10% of patients. Approximately 25% “hear” carotid pulsa-
Penetrating Atherosclerotic Ulcer tions. A carotid bruit and carotidynia may be noted during
the physical examination.
A PAU develops when an inflammatory atherosclerotic
plaque penetrates the internal elastic membrane and ex- MRI is the modality used most commonly to identify
poses the media to the lumen. This permits IMH formation, carotid artery dissections, replacing contrast angiography
classic aortic dissection, or aortic rupture. A PAU generally as the diagnostic standard. Some have advocated the use
occurs in the descending thoracic aorta (the most common of ultrasonography, reporting that abnormal blood flow
site of atherosclerosis) and typically is found in older pa- is noted in more than 90% of patients; however, a dissec-
tients with extensive atherosclerosis. The diagnosis usu- tion, IMH, or intimal flap is noted in less than one-third
ally is made by CT or MRI, which shows an excrescence of patients.
beyond the aortic lumen, with mural thickening, displace-
ment of intimal calcium, and sometimes IMH formation. The treatment of carotid dissection is designed to de-
Most physicians recommend surgery for a patient with crease the rate of thrombosis formation and the possibil-
PAU if the presentation was consistent with an acute event; ity of cerebral embolism. Anticoagulation therapy may be
however, if PAU is discovered incidentally, conservative used; anticoagulation is typically achieved initially with
therapy with radiographic follow-up may be appropriate. heparin and then continued with use of warfarin for 3 to 6
months, with a target international normalized ratio of 2.0
Carotid Artery Dissection to 3.0. Most dissections heal spontaneously. For patients
with persistent symptoms, surgical ligation and bypass
Carotid artery dissection may occur as a result of exten- and percutaneous stenting have been used.
sion of an aortic dissection or may occur spontaneously
in the carotid artery alone. Carotid artery dissections are The prognosis of carotid dissection primarily is related
rare, with an incidence of 2 to 3 cases per 100,000 persons to the severity of the initial ischemic event. The mortality
per year in community-based studies and at about half rate is less than 5% after a carotid artery dissection, and
that rate in hospital-based studies. In the Lausanne Stroke more than 90% of dissections eventually resolve. Most
Registry of 1,200 consecutive patients, carotid artery dis- patients report that head or facial pain resolves within a
sections were the cause of stroke in 2%. In younger pa- week. Two-thirds of dissections recanalize, and one-third
tients, however, carotid dissection caused up to 25% of will decrease in size. Embolic events rarely occur with the
ischemic strokes. The most common age of presentation is development of aneurysms, and the aneurysms do not
40 to 50 years, but dissections may occur at any age. The rupture. After the first 3 months, the risk of recurrence is
mean age at occurrence in women tends to be 5 to 10 years about 1% per year.
younger than that in men.
• Mortality due to carotid dissection is less than 5%
Carotid artery dissection may be idiopathic or the con- • More than 90% of dissections eventually resolve
sequence of a known event. Idiopathic events typically are
ascribed to a congenital abnormality in the arterial wall, Questions
although no specific arteriopathy has been described. Ab-
normalities most commonly associated include those in 1. A 29-year-old pregnant woman presents with severe left
Marfan syndrome, Ehlers-Danlos syndrome, polycystic facial pain and difficulty seeing with the left eye. She
kidney disease, and osteogenesis imperfecta, which char- reports upper back pain but no arm weakness or pain.
acterize about 5% of dissections. However, up to 20% of Physical examination shows a left carotid bruit, ptosis,
patients have an unidentified inherited abnormality. Trau- a crescendo-decrescendo murmur at the upper sternal
ma is the most important acquired mechanism of dissec- borders, and preserved pulses. What is the most appro-
tion and may originate from a quick blow, motor vehicle priate next step?
accident, heavy vomiting or coughing, or chiropractic ma- a. Magnetic resonance imaging
nipulation. Other acquired causes include fibromuscular b. Duplex ultrasonography
dysplasia, vasculitis, and pregnancy.

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CHAPTER 17 Aortic Dissection and Dissection-Like Syndromes

c. Warfarin anticoagulation therapy
d. Heparin anticoagulation therapy

2. A 69-year-old man presents to the emergency depart-
ment with severe, sudden-onset back pain. The patient
rates the pain as a “5” out of 10 but noted that it was
worse before presentation. Physical examination shows
a blood pressure of 175/95 mm Hg in the right and left
arms, clear lungs, a rapid, regular heart rate without
gallop, soft abdomen, and absent pedal pulses on the
left side. Electrocardiography shows sinus rhythm and
left ventricular hypertrophy. Angiographic imaging is
ordered (Figure). Which factor is most associated with
poor outcome?

d. Enoxaparin injection, lower extremity venous ultra-
sonography, inferior vena cava filter placement

4. Which factor is most associated with future aneurysm
repair in patients treated for aortic dissection?
a. Hypertension
b. A thrombosed false lumen
c. Aortic diameter of 4.2 cm
d. Dissection extension into the iliac arteries

a. Hypertension 5. A 63-year-old woman is brought to the emergency de-
b. Left ventricular hypertrophy partment after collapsing at home. Upon arrival, her
c. Persistent back pain systolic blood pressure is 70 mm Hg, and she undergoes
d. Pulse deficit volume resuscitation. She reports severe chest pain be-
fore the collapse and is currently short of breath. Physi-
3. A 69-year-old man presents to the emergency depart- cal examination shows basilar lung crackles, a grade
ment with severe chest pain that resolves over the course 1/4 diastolic murmur, and absent right radial pulse.
of an hour. His blood pressure is 180/100 mm Hg, but Electrocardiography shows ST-segment depressions
physical examination findings are otherwise unremark- in the lateral precordial leads. Transthoracic echocar-
able. Electrocardiography shows T-wave inversions. diography shows signs of ascending aortic dissection,
Chest CT results are shown in the Figure. What is the pericardial tamponade, and mild aortic valvular in-
correct management strategy? sufficiency. What is the most appropriate next step in
a. Esmolol and nitroprusside infusion, emergent cardiac therapy?
surgery consultation a. Emergent pericardiocentesis
b. Oral metoprolol and captopril administration, hos- b. Emergent coronary angiography
pital admission and monitoring, repeated CT in the c. Emergent metoprolol administration
morning d. Emergent surgical referral
c. Chewed aspirin, nitroglycerin patch, oral metoprolol,
and hospitalization to rule out myocardial infarction Suggested Readings

Bogousslavsky J, Despland PA, Regli F. Spontaneous carotid dis-
section with acute stroke. Arch Neurol. 1987;44:137-40.

199

Vascular Medicine and Endovascular Interventions

Cambria RP, Brewster DC, Gertler J, et al. Vascular complications Mehta RH, Suzuki T, Hagan PG, et al, International Registry
associated with spontaneous aortic dissection. J Vasc Surg. of Acute Aortic Dissection (IRAD) Investigators. Predicting
1988;7:199-209. death in patients with acute type A aortic dissection. Circula-
tion. 2002;105:200-6.
Clouse WD, Hallett JW Jr, Schaff HV, et al. Acute aortic dissec-
tion: population-based incidence compared with degenerative Nienaber CA, Richartz BM, Rehders T, et al. Aortic intramural
aortic aneurysm rupture. Mayo Clin Proc. 2004;79:176-80. haematoma: natural history and predictive factors for compli-
cations. Heart. 2004;90:372-4.
Coady MA, Rizzo JA, Hammond GL, et al. Penetrating ulcer of
the thoracic aorta: what is it? How do we recognize it? How do Pepin M, Schwarze U, Superti-Furga A, et al. Clinical and ge-
we manage it? J Vasc Surg. 1998;27:1006-15. netic features of Ehlers-Danlos syndrome type IV, the vascular
type. N Engl J Med. 2000;342:673-80. Erratum in: N Engl J Med.
Doroghazi RM, Slater EE, DeSanctis RW, et al. Long-term surviv- 2001;344:392.
al of patients with treated aortic dissection. J Am Coll Cardiol.
1984;3:1026-34. Schievink WI. Spontaneous dissection of the carotid and verte-
bral arteries. N Engl J Med. 2001;344:898-906.
Evangelista A, Mukherjee D, Mehta RH, et al, International Reg-
istry of Aortic Dissection (IRAD) Investigators. Acute intramu- Slonim SM, Nyman U, Semba CP, et al. Aortic dissection: per-
ral hematoma of the aorta: a mystery in evolution. Circulation. cutaneous management of ischemic complications with
2005 Mar 1;111:1063-70. Epub 2005 Feb 14. endovascular stents and balloon fenestration. J Vasc Surg.
1996;23:241-51.
Gass A, Szabo K, Lanczik O, et al. Magnetic resonance imag-
ing assessment of carotid artery dissection. Cerebrovasc Dis. Stapf C, Elkind MS, Mohr JP. Carotid artery dissection. Annu Rev
2002;13:70-3. Med. 2000;51:329-47.

Hagan PG, Nienaber CA, Isselbacher EM, et al. The International Vilacosta I, Castillo JA, Peral V, et al. Intramural aortic haemato-
Registry of Acute Aortic Dissection (IRAD): new insights into ma following intra-aortic balloon counterpulsation: documen-
an old disease. JAMA. 2000;283:897-903. tation by transoesophageal echocardiography. Eur Heart J.
1995;16:2015-6.
Hirst AE Jr, Johns VJ Jr, Kime SW Jr. Dissecting aneurysm of the
aorta: a review of 505 cases. Medicine. 1958;37:217-79. Wheat MW Jr. Acute dissecting aneurysms of the aorta: diagnosis
and treatment—1979. Am Heart J. 1980;99:373-87.
Januzzi JL, Isselbacher EM, Fattori R, et al, International Registry
of Aortic Dissection (IRAD). Characterizing the young patient Wilson SK, Hutchins GM. Aortic dissecting aneurysms: causative
with aortic dissection: results from the International Registry factors in 204 subjects. Arch Pathol Lab Med. 1982;106:175-80.
of Aortic Dissection (IRAD). J Am Coll Cardiol. 2004;43:665-9.

200

18 Renal and Mesenteric Artery Disease

Jeffrey W. Olin, DO

Renal Artery Disease uncommon. Most patients with atherosclerotic RAS have
one or more of the following features: onset of hyperten-
The past decade has seen increased awareness of renovas- sion before age 30 years or after age 55 years; exacerbation
cular disease as a potentially correctable cause of hyper- of previously well-controlled hypertension; malignant
tension and renal insufficiency. The association between or resistant hypertension; epigastric bruit (systolic or
renal artery stenosis (RAS) and coronary artery disease diastolic); unexplained azotemia; azotemia while receiv-
and congestive heart failure (CHF) has been well studied. ing angiotensin-converting enzyme (ACE) inhibitors or
Patients with RAS have markedly decreased survival as a angiotensin-receptor blockers (ARBs); atrophic kidney or
result of increased incidence of myocardial infarction and discrepancy in size between the two kidneys; recurrent
stroke. RAS may present in one of four ways: 1) hyper- CHF, flash pulmonary edema, or angina; or atherosclero-
tension; 2) acute or chronic renal failure; 3) CHF, “flash” sis in another vessel (coronary arteries, peripheral arterial
pulmonary edema, or unstable angina; or 4) incidentally disease).
discovered on an imaging test performed for some other
reason. The presence of anatomic RAS does not establish RAS
as the cause of the hypertension or renal failure. Primary
• RAS may present in one of four ways: (essential) hypertension can exist for years before the de-
• Hypertension velopment of atherosclerotic RAS later in life. Renal revas-
• Acute or chronic renal failure cularization (with PTA, stent placement, or surgery) may
• CHF, flash pulmonary edema, or unstable angina result in improved blood pressure control in 50% to 80%
• Discovered incidentally of patients, but complete control is unusual in patients
with long-standing hypertension. Ischemic nephropathy
Incidentally discovered RAS is quite common, but reno- or flash pulmonary edema almost always occurs in the
vascular hypertension occurs in only a minority of all pa- presence of bilateral renal artery disease or disease with
tients with hypertension. RAS is most commonly caused a solitary functioning kidney. Percutaneous or surgical
by fibromuscular dysplasia (FMD) or atherosclerosis. revascularization can lead to improvement or stabiliza-
The predominant clinical manifestation of FMD is hyper- tion of renal function and improvement of CHF in care-
tension, which frequently can be cured or substantially fully selected patients.
improved with percutaneous transluminal angioplasty
(PTA). FMD is the primary cause of RAS in young women, • Renal revascularization may result in improved blood
whereas atherosclerosis is most often the cause in persons pressure control in 50%-80% of patients, but complete
older than 55 years. control is unusual in patients with long-standing hyper-
tension
Approximately 90% of all renovascular lesions are sec-
ondary to atherosclerosis. Atherosclerotic RAS most often Pathogenesis of Hypertension in RAS
occurs at the ostium or the proximal 2 cm of the renal
artery. Distal arterial or branch involvement is distinctly A detailed discussion of the pathophysiologic mecha-
nisms of hypertension in renal artery disease is beyond the
© 2007 Society for Vascular Medicine and Biology scope of this chapter. In general, early in the course of the
disease, patients with unilateral RAS have a renin-medi-

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Vascular Medicine and Endovascular Interventions

ated form of hypertension, whereas patients with bilateral The first may involve any antihypertensive agent when
RAS or stenosis with only one functioning kidney have a a critical perfusion pressure is reached, below which the
volume-mediated form of hypertension. In patients with kidney no longer receives adequate perfusion. This mech-
volume-mediated hypertension, administration of an anism has been shown with the infusion of sodium nitro-
ACE inhibitor or ARB does not decrease blood pressure prusside in patients with severe bilateral RAS. When the
or change renal blood flow. Dietary restriction of sodium critical perfusion pressure was reached, the urine output,
or administration of diuretics converts the hypertension renal blood flow, and glomerular filtration rate decreased
to a renin-mediated form and restores sensitivity to ACE and later returned to normal when the blood pressure in-
inhibitors or ARBs. Functional renal insufficiency may creased above this critical perfusion pressure. The exact
occur when an ACE inhibitor is administered to a patient pressure necessary to perfuse a kidney if RAS is present
with bilateral RAS or RAS to a solitary kidney, especially varies with the degree of stenosis and differs among pa-
in the volume-contracted state. tients.

• Patients with unilateral RAS have a renin-mediated The second mechanism is confined to patients receiv-
form of hypertension, whereas patients with bilateral ing an ACE inhibitor or ARB and may occur even without
RAS or stenosis to a solitary functioning kidney have a a marked change in blood pressure. Patients with high-
volume-mediated form of hypertension grade bilateral RAS or RAS to a single functioning kidney
may be highly dependent on angiotensin II for glomeru-
• In volume-mediated hypertension, administration of lar filtration. This is particularly common in patients who
ACE inhibitors or ARBs does not decrease blood pres- receive a combination of ACE inhibitors and diuretics or
sure or change renal blood flow in patients who follow a sodium-restricted diet. The con-
strictive effect of angiotensin II on the efferent arteriole
Pathophysiology of Ischemic Nephropathy allows for the maintenance of normal transglomerular
capillary hydraulic pressure, thus allowing continued
The relationship of ischemic nephropathy to RAS is par- normal glomerular filtration in the presence of markedly
ticularly difficult to fully understand because of several decreased blood flow. When an ACE inhibitor or ARB is
factors. First, no linear relationship exists between the de- administered, the efferent arteriolar tone is no longer main-
gree of RAS and the degree of renal dysfunction. Second, tained and glomerular filtration is therefore decreased. A
it is not easy to determine with certainty whether the renal similar situation occurs in patients with decompensated
insufficiency is attributable to stenosis of the main renal CHF who are sodium depleted.
artery or to parenchymal disease. Third, some patients
undergoing renal revascularization have worsening renal Clinical Manifestations of Renal Artery Disease
function after the procedure. This may be due to athero-
matous embolization caused by the procedure or to the Prevalence
natural history of the underlying disease. The develop-
ment of azotemia while the patient is receiving an ACE In a recent population-based study on the prevalence of
inhibitor or ARB indicates the presence of bilateral RAS, renovascular disease in a cohort of elderly patients, the
RAS to a solitary kidney, or decompensated CHF in the 834 participants underwent renal duplex ultrasonogra-
sodium-depleted state. phy, and 57 (6.8%) were found to have anatomic RAS. The
prevalence of RAS was similar in white and black patients
• There is no linear relationship between the degree of (6.9% vs 6.7%).
RAS and the degree of renal dysfunction
Several series have determined the prevalence of reno-
• It is not easy to determine whether renal insufficiency is vascular disease in patients who have atherosclerotic dis-
due to stenosis of the main renal artery or to parenchy- ease at other sites. In 319 patients reported in six different
mal disease studies, 44% had bilateral RAS. Other studies have shown
that 22% to 59% of patients with peripheral arterial dis-
• Some patients with renal revascularization have wors- ease have significant RAS. RAS also is common in patients
ening renal function after the procedure with coronary artery disease. Of 7,758 patients undergo-
ing cardiac catheterization in the Duke University cardiac
• If azotemia develops while the patient is receiving an catheterization laboratory, 3,987 underwent aortography
ACE inhibitor or ARB, it indicates one of the following: to screen for RAS at the time of catheterization. Of these,
• Bilateral RAS 191 (4.8%) had stenosis greater than 75% in the renal
• RAS to a solitary kidney artery, and 0.8% had severe bilateral disease. In a series
• Decompensated CHF in the sodium-depleted state from Mayo Clinic, renal arteries were studied at the time

Two mechanisms exist by which renal functional impair-
ment can occur with the use of antihypertensive agents.

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CHAPTER 18 Renal and Mesenteric Artery Disease

of cardiac catheterization in patients with hypertension. clinical presentation is hypertension in a young woman.
The renal arteries were adequately visualized in 90% and The vessels involved are the renal arteries in 60% to 75% of
no complications occurred with aortography. RAS was patients with FMD, extracranial cerebral arteries in 25% to
greater than 50% in 19.2% of the patients and was greater 30%, visceral arteries in less than 10%, and arteries of the
than 70% in 7%; bilateral RAS was present in 3.7% of the extremities in less than 5% of patients. Although athero-
patients. sclerosis involves the origin and proximal portion of the
renal arteries, FMD characteristically involves the distal
• 22%-59% of patients with peripheral arterial disease two-thirds of the artery and can involve the branches.
have significant RAS
• FMD accounts for less than 10% of all renal artery dis-
• RAS is common in patients with coronary artery dis- ease
ease
• It most commonly affects the renal arteries; the second
• Rates of progression range from 36%-71% most common cause of RAS

Natural History • FMD characteristically involves the distal two-thirds of
the artery and may involve the branches
Most reports on the natural history of RAS have been
retrospective studies, which show the rate of disease pro- • Medial fibroplasia is the histologic finding in nearly
gression to range from 36% to 71%. In one series, disease 80% of all cases of FMD
progressed to total occlusion in only 16% of patients over
a mean follow-up of 52 months. However, progression to • Intimal fibroplasia occurs in children and young adults
total occlusion occurred more frequently (39%) if initial • It accounts for approximately 10% of all cases of fi-
renal arteriography showed greater than 75% stenosis. brous lesions

Prospective studies of the anatomic progression of The classification of FMD is important because each type of
atherosclerotic renovascular disease, using renal duplex fibrous dysplasia has distinct histologic and angiographic
ultrasonography, have shown that if the renal arteries features, and each type occurs in a different clinical setting
were normal, only 8% of patients had disease progression (Table 18.1).
over 36 months. At 3 years, however, 48% of patients had
disease progression from less than 60% stenosis to 60% or Medial fibroplasia is the histologic finding in nearly
greater stenosis. In the four renal arteries that progressed 80% of all cases of FMD. It tends to occur in women aged
to occlusion, all had 60% or greater stenosis at the initial 25 to 50 years and often involves both renal arteries. It has
visit. Progression of RAS occurred at an average rate of 7% a “string of beads” appearance angiographically, with the
per year for all categories of baseline disease combined. “bead” diameter larger than the proximal, unaffected ar-
In one study, 122 patients (204 kidneys) with known RAS tery. Medial fibroplasia responds well to PTA alone.
were followed up prospectively for a mean of 33 months
with duplex ultrasonography. The 2-year cumulative in- Intimal fibroplasia occurs in children and young adults
cidence of renal atrophy was 5.5%, 11.7%, and 20.8% in and accounts for approximately 10% of all cases of FMD.
kidneys with a baseline renal artery disease classification This lesion is characterized by a circumferential accumu-
of normal, less than 60% stenosis, and 60% or greater ste- lation of collagen inside the internal elastic lamina. Arte-
nosis, respectively (P=.009). riography in intimal fibroplasia shows either a smooth,
long area of narrowing or a concentric band-like focal
Patient survival decreases as the severity of RAS increas- stenosis usually involving the mid portion of the vessel
es; 2-year survival rates are 96% in patients with unilateral or its branches. Progressive renal artery obstruction and
RAS, 74% in patients with bilateral RAS, and 47% in pa- ischemic atrophy of the involved kidney may occur. Al-
tients with stenosis or occlusion to a solitary functioning though intimal fibroplasia most commonly affects the
kidney. In a large study of patients on dialysis, those who renal arteries, it may also occur as a generalized disorder,
progressed to end-stage renal disease secondary to RAS with concomitant involvement of the carotid artery, upper
had a median survival of 25 months and a 5-year survival and lower extremities, and mesenteric vessels, and may
of only 18%. mimic a necrotizing vasculitis.

Fibromuscular Dysplasia Diagnosis of Renovascular Disease

FMD, which accounts for less than 10% of all renal artery The ideal procedure for imaging of the renovascular sys-
disease, is a non-atherosclerotic, non-inflammatory dis- tem should 1) identify the main renal arteries and acces-
ease that most commonly affects the renal arteries and is sory vessels; 2) localize the site of stenosis or disease; 3)
the second most common cause of RAS. The most common provide evidence of the hemodynamic significance of the
lesion; 4) identify any associated pathology (e.g., abdomi-
nal aortic aneurysm, renal mass) that may affect treatment

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Vascular Medicine and Endovascular Interventions

Table 18.1 Classification of Fibromuscular Dysplasia

Classification Frequency, % Pathology Angiographic appearance

Medial dysplasia 75-80 Alternating areas of thinned media and thickened “String of beads” appearance—diameter of the
Medial fibroplasia fibromuscular ridges containing collagen; internal “beading” is larger than the diameter of the
elastic membrane may be lost in some areas artery
Perimedial fibroplasia 10-15
Medial hyperplasia 1-2 Extensive collagen deposition in the outer half of the “String of beads” appearance—the “beads” are
Intimal fibroplasia <10 media smaller than the diameter of the artery

True smooth muscle cell hyperplasia without fibrosis Concentric smooth stenosis (similar to intimal
disease)
Circumferential or eccentric deposition of collagen in
the intima; no lipid or inflammatory component; Concentric focal band; long, smooth narrowing
internal elastic lamina fragmented or duplicated
Adventitial (periarterial) <1
fibroplasia Dense collagen replaces the fibrous tissue of the
adventitia and may extend into surrounding tissue

From Begelman SM, Olin JW. Fibromuscular dysplasia. Curr Opin Rheumatol. 2000;12:41-7. Used with permission.

of the renal artery disease; and 5) detect restenosis after processes such as aneurysms or obstruction. Duplex scan-
renal artery stent implantation or surgical revasculariza- ning also may be helpful for predicting which patients
tion. will have improved blood pressure control or renal func-
tion after renal artery angioplasty and stenting.
Angiography
• Duplex ultrasonography is the least expensive imaging
Angiography, once considered the gold standard for arte- modality
rial imaging, today is rarely required for diagnosing RAS.
Usually, one or more of the non-invasive methods can • It provides useful information about the degree of
accurately assess the renal arteries. CO2 and gadolinium stenosis, the kidney size, and other associated disease
are non-nephrotoxic contrast agents that can be particu- processes
larly useful in patients with renal insufficiency. Although
the practice is controversial, some cardiologists perform • Duplex ultrasonography can help predict which pa-
renal angiography at the time of cardiac catheterization tients will have improved blood pressure control or
routinely in all patients; others image the renal arteries renal function after renal artery angioplasty and stent-
selectively only in those with clinical clues suggesting the ing
presence of RAS. In one series, renal angiography per-
formed at the time of cardiac catheterization showed only As described in detail in Chapter 7, specific duplex ultra-
4.8% of patients to have RAS of more than 75% and only sonographic measurements are used to make the diag-
0.8% to have severe bilateral disease. Similarly, in another nosis of RAS. In the longitudinal view, the peak systolic
prospective evaluation of 297 patients with hypertension, velocity (PSV) in the aorta is recorded at the level of the
only 19% had RAS greater than 50%, 7% had RAS greater renal arteries. The aortic velocity and the highest renal
than 70%, and 3.7% had bilateral disease. This study also artery PSV are used to calculate the renal-aortic ratio. Be-
showed that renal arteries could be evaluated successfully cause the PSV associated with a significant RAS increases
using only 62 mL of contrast agent. Angiography at the relative to aortic PSV, the renal-aortic ratio can be used
time of catheterization is therefore safe, but the yield is to identify severe RAS (Table 18.2). Overall, these duplex
low. In addition, evidence suggests that knowing stenosis ultrasonographic criteria have a sensitivity of 84% to 98%
is present may lead to stenting of the renal artery without and a specificity of 62% to 99% for diagnosing RAS.
definite indication of need.
Table 18.2 Duplex Ultrasonographic Criteria for Diagnosis of Renal Artery
Duplex Ultrasonography Stenosis

Duplex ultrasonography combines B-mode imaging with Stenosis Duplex criteria
Doppler examination and is an excellent method for de-
tecting RAS. It is the least expensive of the imaging mo- <60% RAR <3.5
dalities and provides useful information about the degree 60%-99% RAR ≥3.5 and PSV >200 cm/s
of stenosis, the kidney size, and other associated disease 100% (occlusion) No flow signal from renal artery
Low-amplitude parenchymal signal
Small kidney may or may not be present

RAR, renal-aortic ratio; PSV, peak systolic velocity.

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CHAPTER 18 Renal and Mesenteric Artery Disease

Another measure, the renal resistive index (RRI), can Computed Tomography Angiography
be used to provide information about the extent of renal
artery disease (see also Chapter 7). The RRI is determined Computed tomography angiography (CTA) is a vascular
by obtaining a Doppler waveform from the cortical blood imaging technique that can be performed rapidly and
vessels of the kidney and measuring PSV and end-di- safely for primary assessment of many vascular diseas-
astolic velocity (EDV). The index is calculated with the es. With the advent of multidetector-row CTA, excellent
formula: RRI=(PSV−EDV)/PSV. A retrospective study image quality is now possible, with higher resolution than
using Doppler ultrasonography to predict the outcome of could be obtained previously with single-detector–row
therapy in patients with RAS found that, in patients with technology. Current multidetector-row scanners acquire
an RRI higher than 80, 97% had no improvement in blood up to 64 simultaneous interweaving slices.
pressure and 80% had no improvement in renal function.
The results suggest that increased RRI is an indication CTA has several advantages over conventional angiog-
of structural abnormalities in the small blood vessels of raphy: 1) volumetric acquisition, which permits visualiza-
the kidney. Such small vessel disease has been seen with tion of the anatomy from multiple angles and in multiple
longstanding hypertension associated with nephrosclero- planes after a single acquisition; 2) improved visualization
sis or glomerulosclerosis. However, because several other of soft tissues and other adjacent anatomic structures; 3)
investigators have refuted this study, the RRI should not less invasiveness and thus fewer complications; and 4)
be used as the sole criterion to determine the suitability of lower cost. CTA also has several advantages over MRA,
the patient for renal artery revascularization. including wider availability of scanners, higher spatial
resolution, absence of flow-related phenomena that may
• The RRI is determined by obtaining a Doppler wave- distort MRA images, and the ability to visualize calcifi-
form from the cortical blood vessels of the kidney; cation and metallic implants such as endovascular stents
RRI=(PSV−EDV)/PSV or stent grafts. The disadvantages of CTA compared with
MRA are exposure to ionizing radiation and the need for
• The RRI should not be used as the sole criterion to de- potentially nephrotoxic iodinated contrast agents.
termine suitability for renal artery revascularization
The sensitivity of CTA for detecting RAS ranges from
Renal artery duplex ultrasonography is an excellent meth- 89% to 100% and specificity from 82% to 100%. MRA or
od for the follow-up of RAS after percutaneous therapy or duplex ultrasonography may be the preferred imaging
surgical bypass. Unlike magnetic resonance angiography modality in patients with impaired renal function.
(discussed below), which can be affected by artifact or
scatter produced by the stent, ultrasonographic transmis- • CTA has a sensitivity of 89%-100% and a specificity of
sion through the stent is not a problem. 82%-100% for assessment of RAS

Magnetic Resonance Angiography Captopril Renography

Magnetic resonance angiography (MRA) provides excel- Radionuclide imaging techniques are a non-invasive and
lent imaging of the abdominal vasculature and associated safe way to evaluate renal blood flow and excretory func-
anatomic structures. Contrast-enhanced (with gadolin- tion. Addition of an ACE inhibitor such as captopril to
ium) MRA provides superior quality compared with non- isotope renography improves the sensitivity and specifi-
contrast studies. MRA has shown a sensitivity of 90% to city of the test considerably, especially for patients with
100% and a specificity of 76% to 94%. In a meta-analysis of unilateral RAS. In most instances of unilateral RAS, the
499 patients who underwent gadolinium-enhanced MRA glomerular filtration rate (GFR) of the stenotic kidney
and catheter angiography (performed less than 3 months decreases by approximately 30% after captopril adminis-
apart), the sensitivity and specificity of MRA were 97% tration. In contrast, the contralateral normal kidney has
and 93%, respectively. MRA accurately identified acces- increased GFR, urine flow, and salt excretion, despite a
sory renal arteries in 82% of patients. However, MRA does decrease in systemic blood pressure.
not have the same sensitivity and specificity in patients
with FMD because the resolution in the smaller blood ves- • Addition of captopril to isotope renography (captopril
sels is not optimal. renography) improves the sensitivity and specificity of
the test considerably, especially for patients with unilat-
• MRA has a demonstrated sensitivity of 90%-100% and a eral RAS
specificity of 76%-94% for diagnosis of RAS
• In unilateral RAS, the GFR of the stenotic kidney usu-
ally decreases by 30% after captopril administration

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Vascular Medicine and Endovascular Interventions

• In contrast, the normal kidney has increased GFR, urine Table 18.3 Indications for PTA With or Without Stent Implantation to
flow, and salt excretion despite a decrease in systemic Treat Atherosclerotic Renal Artery Stenosis
blood pressure
1) At least 70% stenosis of one or both renal arteries AND
Overall, the accuracy of captopril renography for identify- a) An inability to adequately control blood pressure despite a good
ing patients with renovascular disease is acceptable, with a antihypertensive regimen OR
sensitivity of 85% to 90% (range, 45%-94%) and specificity b) Chronic renal insufficiency not related to another clear-cut cause;
of approximately 93% to 98% (range, 81%-100%). Patients disease should be bilateral or comprise stenosis to a solitary
with unilateral disease and normal renal function are the functioning kidney
best candidates for captopril renography. The presence of (The treatment of elevated serum creatinine level in a patient with
significant azotemia or bilateral RAS may adversely affect unilateral disease is controversial, and no clinical trials exist to help
the accuracy of captopril renography. guide the clinician.)

Although captopril renography was once the non-inva- 2) Dialysis-dependent renal failure in a patient without another definite
sive diagnostic test of choice for patients with RAS, it is cause of end-stage renal disease and bilateral disease or severe stenosis
now a secondary screening method because the quality of to a single kidney
the images from duplex ultrasonography, CTA, and MRA
is superior. 3) Recurrent congestive heart failure or “flash” pulmonary edema not
attributable to active ischemia

PTA, percutaneous transluminal angioplasty.

Management of Renal Artery Disease renal function. Controversy still exists as to the value of
renal artery stenting and the appropriate indications for
Medical Therapy this procedure. The accepted indications for PTA with or
without stent implantation for atherosclerotic RAS are
All patients with renal artery disease and hypertension shown in Table 18.3.
should be treated medically, even if they undergo inter-
vention. A comprehensive risk factor reduction program Because restenosis rates with angioplasty alone are
should be undertaken, because this patient population high, endovascular stents offer a significant advantage
has markedly increased cardiovascular morbidity and over angioplasty alone in patients with atherosclerotic
mortality. Many patients have superimposed essential hy- disease. The degree of stenosis after stenting approaches
pertension and require lifelong antihypertensive therapy zero, and most dissection flaps caused by PTA alone are
even after renal artery revascularization. Patients with successfully treated with stents.
RAS who are treated solely with medical therapy should
be carefully followed up for disease progression, gener- For the best results, the lesion should be completely
ally with a surveillance program of serial duplex ultra- covered, the stent should extend 1 to 2 mm into the aorta
sonographic imaging. Renal function should be evaluated in patients with ostial disease, and the stent must be fully
every 3 months. expanded. Underdeployment of the stent is a common
problem early in an operator’s experience. For a less-ex-
• Many patients have superimposed essential hyperten- perienced operator, it may be worthwhile to perform the
sion and require lifelong antihypertensive therapy even first several cases with intravascular ultrasonography to
after renal artery revascularization be certain the stent is adequately expanded. It is also im-
portant to make sure that no postprocedure translesional
Percutaneous Transluminal Angioplasty and pressure gradient exists.
Stenting
In one prospective study, a balloon-expandable stent
PTA is the treatment of choice for patients with FMD. In was placed in 68 patients (74 lesions) with ostial RAS and
contrast, stent implantation is the preferred endovascular suboptimal PTA. Patency at 5 years was 84.5% (mean fol-
therapy for patients with atherosclerosis, especially if the low-up, 27 months). Restenosis occurred in 8 of 74 arter-
disease involves the ostium or proximal portion of the ies (11%), but after reintervention, the secondary 5-year
artery. Since the introduction of stents, surgical revascu- patency rate was 92.4%. Hypertension was cured or im-
larization is rarely performed solely for the treatment of proved in 78% of patients. Serum creatinine value did not
renal artery disease. change significantly after stent implantation.

Despite advances in the technical aspects of PTA and A meta-analysis of 14 studies (678 patients) compared
stent implantation, few controlled clinical trials have as- the technical success, clinical efficacy, and restenosis rates
sessed the effectiveness of renal artery angioplasty and after PTA and stent implantation. Blood pressure was im-
stenting for the control of hypertension or to preserve proved in 60% to 80% of patients, and renal function was
improved or stabilized in approximately 75% of patients.
The restenosis rate among contemporary series was in the
range of 11% to 20%.

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CHAPTER 18 Renal and Mesenteric Artery Disease

• PTA is the treatment of choice for patients with FMD for renal replacement. All patients who receive a stent will
• Renal artery stents: also receive a distal protection device. Multiple secondary
end points will assess quality of life, health policy per-
• Endovascular stents and angioplasty offer a signifi- spectives, and cost effectiveness. This well-designed trial
cant advantage over angioplasty alone in patients will provide critically needed information on the utility of
with atherosclerotic disease renal artery stenting.

• In a meta-analysis of 14 studies (678 patients): Surgical Revascularization
• Hypertension was improved in 60%-80% of patients
• Renal function was improved or stabilized in 75% Surgical revascularization now has a much smaller role
of patients than it did previously because of the excellent technical
• The restenosis rate among contemporary series results that can be achieved with angioplasty and stent
was 11%-20% implantation. Many patients can now undergo renal ar-
tery stent implantation as an outpatient procedure at a
The effect of renal artery stent implantation on preserv- fraction of the cost of surgical revascularization.
ing renal function was studied in two small series; both
used the reciprocal of the serum creatinine value (1/Scr) Current indications for surgical revascularization in-
to determine the rate of deterioration or improvement in clude branch disease from FMD that cannot be adequately
renal function. The first study, in which renal artery stents treated with PTA, recurrent stenosis after stenting (which
were placed in 32 patients (33 arteries), reported that renal is extremely rare), or simultaneous aortic surgery (abdom-
function improved or stabilized in 22 patients (69%). The inal aortic aneurysm repair or symptomatic aortoiliac dis-
second study, which included 25 patients with complete ease). In the event of simultaneous aortic surgery, it may
follow-up, showed that after stent placement, the slopes be advisable to place a stent in the renal artery first and
of the 1/Scr curves were positive in 18 patients and less then proceed with aortic reconstruction. The mortality
negative (than previously) in 7 patients. rate for aortic replacement and renal artery revasculariza-
tion is higher than for either procedure alone.
Complications of renal artery stent placement include
access-related complications such as hematoma, retro- Revascularization for Renal Salvage. Patients with bilat-
peritoneal hemorrhage, pseudoaneurysm, arteriovenous eral RAS of greater than 70% or severe stenosis to a sin-
fistula, vessel occlusion, or infection. However, the most gle functioning kidney are at a markedly increased risk
serious complications result from atheromatous emboli- of renal failure. In this patient subgroup, the risk of total
zation to the kidneys, bowel, or legs. Stent malposition occlusion of the renal artery is significant; if occlusion oc-
and rupture of the renal artery are less common complica- curs, the outcome is a critical decrease in functioning renal
tions. The complication rate varies considerably between mass with resulting renal failure.
centers. High-volume centers generally can perform renal
artery stenting with minimal morbidity and mortality. Al- Complete occlusion of the renal artery most often re-
though all studies reported use of an antithrombotic agent sults in irreversible ischemic damage to the involved
during the procedure and most patients were discharged kidney. However, in some patients with gradual arterial
on antiplatelet therapy, the regimens varied. occlusion, the kidney may remain viable because of devel-
opment of a collateral arterial supply. Clues that can help
Embolic protection devices have been used in several predict kidney salvage in patients with an occluded renal
series—a wire is placed across the renal artery lesion and artery include angiographic demonstration of late filling
a balloon occlusion device or a filter device is deployed of the distal renal arterial tree by collateral vessels on the
in the distal renal artery. This device is designed to cap- side of total arterial occlusion; a renal size of 8 to 9 cm;
ture the atherosclerotic debris caused by angioplasty and functioning of the involved kidney on a renal flow scan;
stenting, with the goal of preventing atheromatous em- appearance of a nephrogram after a contrast arteriogram;
bolization to the kidneys. In one study using an embolic or renal biopsy results showing well-preserved glomeruli
protection device in 28 patients (32 arteries), the proce- and an absence of significant glomerulosclerosis.
dure was technically successful in all patients, and visible
debris was recovered in all patients. The Cardiovascular Some reports have shown that restoration of renal
Outcomes in Renal Atherosclerotic Lesions (CORAL) ran- function in patients with complete occlusion of the renal
domized multicenter trial, currently recruiting patients arteries is feasible with endovascular therapy or surgical
with hypertension, aims to compare combined medical revascularization. In a study of 340 patients undergoing
therapy and stenting of hemodynamically significant RAS surgical renal revascularization between 1987 and 1993, 20
with medical therapy alone. The primary composite car- patients were receiving hemodialysis before renal artery
diovascular and renal end point is cardiovascular or renal repair. Hemodialysis was no longer required in 16 of the
death, myocardial infarction, hospitalization for CHF, 20 patients (80%); two of the 16 resumed dialysis 4 and 6
stroke, doubling of serum creatinine value, and the need

207

Vascular Medicine and Endovascular Interventions

months after surgery. The long-term survival was better ment is nearly always fatal. Surgical treatment includes
in those who were dialysis independent than in those who laparotomy, revascularization of the ischemic intestine
required ongoing dialysis therapy. Only two late deaths with assessment of intestinal viability after revasculari-
occurred among the 14 patients not receiving dialysis, ver- zation, and resection of non-viable intestine. A “second
sus five late deaths among the six patients who continued look” operation 24 to 48 hours later is generally war-
to receive dialysis after surgical revascularization (P<.01). ranted.
Another study reported on 304 patients with RAS and
serum creatinine levels higher than 2.0 mg/dL who un- Acute Non-Occlusive Intestinal Ischemia
derwent surgical revascularization. With a mean follow-
up of 3 years, 83 patients (27.3%) had an improvement in Intestinal infarction may occur in the absence of fixed
renal function, 160 (52.6%) had no change, and 61 (20.1%) arterial obstruction. This usually occurs in persons with
had a worsening of renal function. severe systemic illness and results in shock and decreased
cardiac output. Intestinal infarction often leads to severe
The likelihood of renal function improving appears to prolonged intestinal vasospasm. Drugs such as cocaine,
be dependent on the severity of stenosis in the main renal ergotamines, and vasopressors (to treat shock) may also
artery, the rapidity of renal failure development, and the result in severe intestinal vasospasm and infarction.
degree of parenchymal damage to the kidney. Several
investigators have suggested that parenchymal damage Non-occlusive mesenteric ischemia is notoriously dif-
may be the most important determinant of the non-revers- ficult to diagnose. It should be suspected in patients in
ibility of renal failure. shock with abdominal pain and distention. Arteriography
is the method of choice for diagnosis. If non-occlusive
Revascularization for Control of CHF or Flash Pulmonary mesenteric ischemia is confirmed, direct intra-arterial va-
Edema. An emerging indication for renal revasculariza- sodilators should be administered. The presence of con-
tion is treatment of patients with CHF or flash pulmonary tinued abdominal symptoms after relief of the vasospasm
edema. This group of patients most often has significant is a clear indication for laparotomy to search for necrotic
bilateral RAS or RAS to a solitary functioning kidney bowel.
and may have no other clear-cut reason (e.g., coronary
ischemia) for recurrent CHF. • Non-occlusive mesenteric ischemia is notoriously dif-
ficult to diagnose
The mechanism by which RAS causes CHF and pul-
monary edema is not well defined. Improvement after • Intestinal infarction may occur in the absence of fixed
stenting may be related in part to the ability to use ACE arterial obstruction
inhibitors, especially for those with impaired left ventricu-
lar function, and the ability to better control volume. • Arteriography is the method of choice for diagnosis
• If non-occlusive mesenteric ischemia is confirmed, di-
Mesenteric Artery Disease
rect intra-arterial vasodilators should be administered
Acute Mesenteric Ischemia to identify necrotic bowel

Acute mesenteric ischemia is a medical emergency. It has Chronic Intestinal Ischemia
many possible causes, including embolization from the
heart or proximal vessels and arterial thrombosis. Ap- Chronic intestinal ischemia is usually caused by athero-
proximately two-thirds of patients presenting with acute sclerosis; less commonly, it can be caused by giant cell
intestinal ischemia are women, with a median age of 70 arteritis, Takayasu arteritis, or FMD. Although atheroscle-
years. Abdominal pain is universally present, and the pain rosis of the celiac, superior mesenteric, and inferior me-
may be out of proportion to the physical findings. In pa- senteric arteries is common, the clinical manifestations of
tients with a delayed presentation, or in those with a high chronic intestinal ischemia are quite uncommon. It is often
likelihood of non-occlusive mesenteric ischemia, arteri- thought that severe stenosis or occlusion of two of the
ography may be indicated as a diagnostic test. However, three intestinal vessels must be present to induce clinical
for those with an acute presentation and a high likelihood manifestations, but in some well-documented cases only
of arterial obstruction or bowel infarction, immediate ex- one vessel was involved, usually the superior mesenteric
ploratory surgery is required. artery.

The natural history of acute intestinal ischemia caused The classic presentation is abdominal pain occurring
by obstruction of intestinal arteries in the absence of treat- after eating. However, the relationship to food is not always
present, perhaps because of unconscious food avoidance.
Weight loss invariably occurs owing to reduced caloric
intake. A female preponderance has been observed.

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CHAPTER 18 Renal and Mesenteric Artery Disease

Diagnosis of Chronic Intestinal Ischemia spontaneously, no such case has been documented in the
literature.
Duplex ultrasonography, CTA, MRA, and catheter-based
angiography are all good imaging techniques to demon- Treatment
strate diseased intestinal vessels. Stenosis or occlusion
of the mesenteric vessels is common, although sympto- Increasingly, reports are showing that percutaneous in-
matic intestinal ischemia is rare. No diagnostic tests can terventional treatment of intestinal arterial obstructions
establish the diagnosis definitively. The diagnosis relies is possible, with a high technical success rate and few
on the combination of the typical clinical presentation of complications in properly selected cases. One study re-
abdominal pain and weight loss and the presence of other ported on 59 consecutive patients with chronic mesenteric
cardiovascular disease, combined with the finding of in- ischemia who underwent stent placement. All patients had
testinal arterial obstruction. clinical follow-up, and 90% had anatomic follow-up with
angiography (CTA or conventional) or ultrasonography at
• No diagnostic tests can establish the diagnosis of chron- least 6 months after the procedure. Success was obtained
ic intestinal ischemia definitively in 96% (76 of 79 arteries) and symptom relief occurred in
88% (50 patients). With a mean follow-up of 38±15 months
• The diagnosis relies on the combination of the typical (range, 6-112 months), 79% of the patients remained alive
clinical presentation: and 10 (17%) had recurrence of symptoms. Angiography
• Abdominal pain and weight loss or ultrasonography at 14±5 months after the procedure
• Presence of other cardiovascular disease showed a restenosis rate of 29%. All patients with recur-
• Presence of intestinal arterial obstruction rent symptoms had angiographic in-stent restenosis and
were successfully revascularized percutaneously.
Because the atherosclerotic lesions that typically produce
intestinal arterial obstruction are usually located at the To date, no prospective therapeutic trials have been
origin of the celiac, superior mesenteric, and inferior me- conducted, and follow-up information is limited. Relief
senteric arteries, duplex ultrasonography is an effective of symptoms and weight gain reliably follow elimina-
non-invasive method for diagnosis. Duplex scanning of tion of the arterial obstruction. Several recent reports of
visceral vessels is technically difficult but can be accom- concurrent series treated with angioplasty and stenting
plished in more than 85% of subjects in the elective setting. or surgery indicate that recurrences after percutaneous
The test has an overall accuracy of approximately 90% for procedures have been more frequent than after open
detection of stenoses greater than 70% or occlusions of the surgery, but many of the recurrences can be managed by
celiac and superior mesenteric arteries, when performed percutaneous interventions. Therefore, it is important for
in laboratories experienced in this technique. Both CTA patients to have ultrasonographic surveillance after angi-
and gadolinium-enhanced MRA are well suited for visual- oplasty and stenting of the mesenteric arteries. Recurrent
izing the typical atherosclerotic lesions at the origins of the symptoms have nearly always indicated recurrent arterial
intestinal arteries. All of the non-invasive techniques are obstruction.
less suited for visualizing the more distal intestinal arter-
ies and for diagnosis of some of the more unusual causes Surgical treatment of chronic intestinal ischemia is ac-
of intestinal ischemia. Arteriography remains the gold complished by endarterectomy or bypass grafting, with
standard for the diagnosis of chronic intestinal ischemia. most surgeons preferring the latter. Long-term patency
and relief of symptoms are the rule, with few recurrences.
• The atherosclerotic lesions that typically produce in- Essentially all symptomatic recurrences are the result of
testinal arterial obstruction are usually located at the recurrent stenosis or occlusion of visceral arteries or the
origin of the celiac, superior mesenteric, and inferior reconstructions.
mesenteric arteries
Questions
• Duplex scanning has an overall accuracy of ≈90% for
detection of >70% diameter stenosis or occlusion of the 1. An 86-year-old man presented with bilateral 95% steno-
celiac and superior mesenteric arteries sis of the renal arteries. His blood pressure was 180/100
mm Hg and serum creatinine value was 1.3 mg/dL. He
The natural history of symptomatic chronic intestinal was started on lisinopril, 40 mg daily. Three weeks later,
ischemia is only partly known. An unknown percentage his blood pressure was 178/98 mm Hg and serum cre-
of patients have progression to acute intestinal ischemia atinine value was 1.2 mg/dL. What is the most likely
and the rest have progressive weight loss with ultimate reason that his blood pressure and renal function did
death from starvation. Although it is reasonable to pos- not change with ACE inhibitor therapy?
tulate that some of the affected patients must recover

209

Vascular Medicine and Endovascular Interventions

a. Bilateral RAS is a volume-mediated form of hyper- 4. Which of the following is the best indication for renal
tension, thus the patient did not respond to ACE in- artery stent implantation?
hibitors. a. Increased blood pressure in a 30-year-old woman
with perimedial fibroplasia of the left renal artery
b. With such a severe degree of stenosis, the ACE inhibi- b. A serum creatinine value of 3.5 mg/dL in an 80-year-
tor is not filtered, thus it has no effect on the kidney. old man with 95% right RAS and 20% left RAS
c. A blood pressure of 190/104 mm Hg in a 76-year-old
c. Bilateral RAS is a renin-mediated form of hyperten- man with 80% bilateral RAS receiving hydrochloro-
sion, thus the patient would require the use of both a thiazide (25 mg/d), atenolol (100 mg/d), enalapril
diuretic and an ACE inhibitor. (10 mg twice daily), and terazosin (10 mg/d)
d. A blood pressure of 132/80 mm Hg and a serum cre-
d. The blood pressure is so high that two or more drugs atinine value of 1.4 mg/dL in a 65-year-old man tak-
are needed to decrease it to normal levels. ing five drugs for his blood pressure, with 60% right
RAS and 40% left RAS
2. A 28-year-old woman presents with blood pressures
ranging from 150/92 to 180/104 mm Hg. An epigastric 5. A 68-year-old woman was admitted to the medical in-
long systolic bruit is detected. Serum creatinine level tensive care unit with septic shock. She was treated with
is 0.7 mg/dL. Angiography of the renal arteries shows intravenous antibiotics and large doses of pressors. Her
that the left renal artery is normal but the right renal systolic blood pressure ranged from 80 to 100 mm Hg.
artery has a “string of beads” in the mid renal artery, Pressors were discontinued on day 3 because the systo-
extending for 2 cm into each of two branches off the lic blood pressures were consistently greater than 100
main renal artery. What is the treatment of choice for mm Hg. Later on the third hospital day, severe abdomi-
this woman? nal pain and marked distention developed. Angiogra-
a. Start antihypertensive therapy; if the blood pressure phy at that time showed 50% stenosis of the superior
is well controlled, no further therapy is needed. mesenteric artery and 60% stenosis of the celiac artery.
b. Perform PTA of the right renal artery and the two The inferior mesenteric artery was patent and normal.
branches. Irregularities were noted in the intestinal branches, the
c. Perform stent implantation into the main renal artery arcades could not be visualized, and no filling of the
and angioplasty in the two branches. intramural vessels was seen. What is the treatment of
d. Perform surgical bypass using saphenous vein graft. choice for this patient?
a. Immediate surgical exploration and resection of
3. Renal artery duplex ultrasonography is performed in a ischemic bowel if present
75-year-old woman. Results are shown in the table. Her b. PTA and stent implantation of the celiac and superior
blood pressure is 170/92 mm Hg and she is receiving mesenteric arteries
hydrochlorothiazide (25 mg/d), lisinopril (40 mg/d), c. Infusion of papaverine into the intestinal vessels
and metoprolol (100 mg/d). The aortic PSV is 55 cm/s. d. Antibiotics, fluid resuscitation, and expectant wait-
ing
Renal artery
Suggested Readings
Measurement Right Left
Blum U, Krumme B, Flugel P, et al. Treatment of ostial renal-ar-
PSV, cm/s 302 190 tery stenoses with vascular endoprostheses after unsuccessful
EDV, cm/s 88 55 balloon angioplasty. N Engl J Med. 1997;336:459-65.
Kidney size, cm 10.3 10.5
RRI 0.79 0.69 Caps MT, Zierler RE, Polissar NL, et al. Risk of atrophy in kid-
neys with atherosclerotic renal artery stenosis. Kidney Int.
How would you interpret these renal artery duplex ul- 1998;53:735-42.
trasonography results?
a. Renal arteries are normal. Conlon PJ, Little MA, Pieper K, et al. Severity of renal vascular
b. The renal arteries are normal but there is markedly disease predicts mortality in patients undergoing coronary
angiography. Kidney Int. 2001;60:1490-7.
increased resistance within the kidneys.
c. Results show an 85% stenosis of the right renal artery Gray BH, Olin JW, Childs MB, et al. Clinical benefit of renal artery
angioplasty with stenting for the control of recurrent and re-
and a 40% stenosis of the left renal artery. fractory congestive heart failure. Vasc Med. 2002;7:275-9.
d. The left renal artery is narrowed 0%-59%, and the

right renal artery shows 60%-99% stenosis.

210

CHAPTER 18 Renal and Mesenteric Artery Disease

Hansen KJ, Edwards MS, Craven TE, et al. Prevalence of renovas- Rundback JH, Sacks D, Kent KC, et al, AHA Councils on Car-
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Henry M, Klonaris C, Henry I, et al. Protected renal stenting with Safian RD, Textor SC. Renal-artery stenosis. N Engl J Med.
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for renal arterial stenosis: where do we stand? A meta-analysis. larization in patients with renal artery stenosis. Circulation.
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Mailloux LU, Napolitano B, Bellucci AG, et al. Renal vascular Silva JA, White CJ, Collins TJ, et al. Endovascular therapy for
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giography for the diagnosis of renal artery stenosis: a meta-
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211

19 Carotid Artery Disease and Stroke

Michael R. Jaff, DO

Introduction Table 19.1 Stroke Facts

Stroke is the third leading cause of death in the United More than 750,000 strokes occur annually in the United States.
States and the second leading cause worldwide (Table Approximately 30% of all strokes are attributable to extracranial
19.1). Over 20% of patients die from acute stroke, and the
mortality rate is as high as 50% at 5 years. Stroke is the atherosclerotic carotid artery disease.
leading cause of adult disability and is perhaps the athero- Stroke is the third leading cause of death in the United States.
sclerotic complication most dreaded by patients and their Stroke is the most common cause of disability for adults in the United
families. More than 750,000 strokes occur annually in the
United States, and one-third are due to extracranial carot- States.
id atherosclerosis. Although dissection of the internal ca-
rotid artery, fibromuscular dysplasia (FMD), arteritis, and 14% for patients with amaurosis fugax and 27% for pa-
trauma may result in cerebrovascular ischemia, athero- tients with hemispheric TIA as the initial cerebrovascular
sclerosis is the most common cause of disease involving symptom. The NASCET study showed a 2-year risk of
the extracranial internal carotid artery. fatal and non-fatal stroke of 17% after transient monocular
blindness and 42% after hemispheric TIA.
Extracranial Carotid Artery Stenosis and
Stroke Risk • The risk of stroke increases as the severity of the carotid
stenosis increases
The risk of stroke increases as the severity of carotid ste-
nosis increases. The stroke rate for patients with carotid • In the NASCET study, the cumulative rate of cerebral
stenosis of 75% or less is 1.3% per year, whereas the rate is infarction was 14% for patients with amaurosis fugax
10.5% per year if stenosis is greater than 75%. In the North and 27% for patients with hemispheric TIA as the initial
American Symptomatic Carotid Endarterectomy Trial cerebrovascular symptom
(NASCET), symptomatic patients with 70% to 99% carotid
stenosis had a 26% risk of ipsilateral stroke and a 28% risk Regardless of the anatomic location, carotid plaque in-
of any stroke over 2 years of follow-up. However, the risk creases the risk of stroke. The pathogenesis of stroke in ex-
of subsequent stroke may differ on the basis of the initial tracranial carotid stenosis is a function of decreased vessel
cerebrovascular symptom. A retinal transient ischemic at- diameter, superimposed thrombosis, and embolization of
tack (TIA) such as amaurosis fugax was associated with thrombotic material. This has been shown by transcranial
an annual stroke rate of 2%. During more than 7 years of Doppler ultrasonography in patients with transient mon-
follow-up, the cumulative rate of cerebral infarction was ocular blindness. Certain alterations in plaque morphol-
ogy may lead to clinical symptoms; as in the coronary cir-
© 2007 Society for Vascular Medicine and Biology culation with acute coronary syndromes, plaque rupture
has been postulated to result in acute stroke. In contrast to
the pathophysiology of acute coronary syndromes, only
a minority of symptoms of atherosclerotic carotid artery
stenoses are caused by thrombotic occlusion or hemody-
namic impairment; most symptoms are a result of emboli
(plaque rupture, ulceration).

212

CHAPTER 19 Carotid Artery Disease and Stroke

Progression of Carotid Stenosis patients with extracranial carotid artery disease is deter-
mining both the symptomatic status of the patient and the
The rate of disease progression for established extracrani- degree of stenosis. Treatment options and their outcomes
al carotid artery stenosis is approximately 20% to 40%. In vary greatly depending on whether the carotid artery ste-
one prospective natural history study of 232 patients with nosis is symptomatic.
mild or moderate carotid stenosis (<50% and 50%-79%,
respectively), carotid duplex ultrasonography (CDUS) Symptoms suggestive of cerebral ischemia are catego-
was performed annually for a mean of 7 years. Disease rized by the location and amount of the brain affected and
progressed in 23% of the patients, half of whom had pro- by the duration and reversibility of the symptoms. For
gression to severe stenosis (80%-99%) or occlusion. Risk of example, transient retinal ischemia (amaurosis fugax) is
progression to severe stenosis or occlusion was higher for described as a “dark shade” or loss of vision in one visual
patients with stenosis initially categorized as 50% to 79% field that typically resolves within minutes. Symptoms
than for those with stenosis less than 50%. such as aphasia and contralateral hemiparesis or hemi-
paresthesia may originate from the dominant hemisphere.
More recently, in a study of 425 asymptomatic patients Non-dominant hemispheric ischemia results in a patient’s
with 50% to 79% carotid stenosis, progression of stenosis lack of awareness of symptoms (anosognosia). Posterior
was observed in 17% of 282 arteries that were evaluated by circulation ischemia (vertebrobasilar insufficiency) causes
at least 2 serial CDUS examinations (mean follow-up, 38 symptoms of dysarthria, diplopia, vertigo, syncope, tran-
months). The incidence of ipsilateral stroke, however, was sient confusion, or a combination of the these symptoms.
low despite the rate of disease progression (0.85% at 1 year, A reversible ischemic neurologic deficit is a similar phe-
3.6% at 3 years, 5.4% at 5 years). Nonetheless, all natural nomenon with symptoms lasting up to 24 hours. A stroke
history studies have shown that more severe stenoses are (cerebrovascular accident) is a more permanent manifes-
associated with increased risks of disease progression and tation of cerebral ischemia, with symptoms lasting more
subsequent stroke. Of 242 asymptomatic patients with dif- than 24 hours.
ferent degrees of carotid stenosis, 35 patients (14%) had a
stroke or TIA. However, patients with 80% to 99% carotid Palpation of the carotid artery upstroke gives non-spe-
stenosis had an annual neurologic event rate of 20.6%. cific physical findings. A diminished carotid upstroke
might suggest cardiac valvular pathology or a global de-
Internal carotid artery occlusion is an unpredictable crease in left ventricular systolic function. In fact, occlu-
clinical dilemma. In a retrospective review of 167 patients sion of the internal carotid artery often is accompanied
with carotid occlusion who presented with no symptoms by a normal carotid upstroke because the internal carotid
(27%), stroke (43%), or TIA (17%), 30 patients (18%) had a artery is located cephalad to the angle of the mandible.
stroke during follow-up (mean, 39 months), 67% (20) of However, the finding of a cervical bruit has clinically sig-
which were ipsilateral to the occlusion. Consistent with nificant implications.
other reports, heart disease was the cause of death in 22 of
the 54 patients (41%) who died during follow-up. The con- Carotid Bruits and the Risk of
tralateral stroke event rate was 33%; the 5-year stroke-free Cardiovascular Disease
rate for patients with stenoses of 50% to 99% was slightly
lower than that for patients with stenoses less than 50% Cervical bruits may have several causes (Table 19.2). Es-
(77% vs 94%; P=.08). timates of the prevalence of asymptomatic carotid bruits
in adults range from 1% to 2.3% for patients aged 45 to 54
Plaque ulceration clearly increases the risk of subsequent
stroke. As in the coronary arterial bed, the pathophysiol- Table 19.2 Causes of Cervical Bruits
ogy of plaque rupture, foam cell infiltration, and thin-
ning of the fibrous cap occurs more often in patients with Bruit
symptomatic (rather than asymptomatic) carotid stenosis.
During 2 years of follow-up of medically treated patients Systolic Diastolic Systolic and
in the NASCET study, plaque ulceration increased the risk only
of ipsilateral stroke from 26.3% to 73.2% as the degree of Cause only diastolic
stenosis progressed from 75% to 99%. For patients with-
out plaque ulceration, the 2-year stroke risk was 21.3%, Carotid atherosclerosis ✓ ✓ ✓
regardless of the degree of stenosis. Thyrotoxicosis ✓ ✓ ✓
Transmitted cardiac murmur ✓
History and Physical Examination ✓ ✓
Aortic stenosis ✓ ✓
Perhaps the most important aspect of the evaluation of Aortic insufficiency
Arteriovenous fistula
Venous hum

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Vascular Medicine and Endovascular Interventions

years and 8.2% for patients 75 years or older. However, mortality risk (2 or 3 risk factors showed annual mortality
in a selected series of patients scheduled to undergo vas- rates of 11.3% and 13%, respectively).
cular surgical procedures, the incidence of cervical bruits
ranged from 6% to 16% (mean prevalence, 10%). The risk • The presence of a carotid bruit does not predict the se-
of a carotid bruit developing in patients aged 65 years or verity of carotid stenosis
older is approximately 1% per year, nearly twice the rate
in patients aged 45 to 54 years. • Incidence of coronary artery disease and coronary mor-
tality in patients with carotid disease is much higher
The implications of an asymptomatic carotid bruit are than that in the general population
vast. The incidence of subsequent stroke for a patient with
an asymptomatic carotid bruit ranges from 1.5% annually • A study of 506 patients with extracranial carotid ar-
to 2.1% in 3 years, as shown by the European Carotid Sur- tery disease and symptomatic or asymptomatic bruits
gery Trial. In this study, the 3-year risk of stroke for 127 pa- showed that 35% had severe coronary artery disease
tients with severe carotid stenosis (70%-99%) was 5.7%. that required revascularization or that had progressed
to an inoperable status
This association of asymptomatic carotid bruits with sub-
sequent stroke may not be as strong in the elderly popula- Differential Diagnosis of Cerebral
tion. In a study of 241 nursing home residents (mean age, Ischemia, Stroke, and Carotid Artery
86 years), 12% had asymptomatic carotid bruits. Incidence Disease
varied with age—8% for patients aged 75 to 84 years, 10%
for those aged 85 to 94 years, and 13% for patients aged There are many causes of stroke other than carotid artery
95 years or older. However, the 3-year incidence of stroke disease (Table 19.3). The most common cause is an em-
was the same for patients with a bruit (10%) and without bolic event, most often from a cardiac source. If a cardiac
a bruit (9%). Of interest, the bruit was undetectable dur- cause is suspected, electrocardiography and echocardiog-
ing follow-up in 60% of the surviving residents, with no raphy can be used to identify non-valvular atrial fibrilla-
occurrences of stroke or cerebrovascular events. tion, rheumatic mitral valve disease, and cardiac chamber
thrombi (prior myocardial infarction). A common source
The presence of a carotid bruit does not adequately of cerebral emboli is aortic arch atherosclerosis, which
predict the severity of carotid stenosis. In a substudy of is identified with transesophageal echocardiography.
the NASCET, 1,268 patients with recent transient cerebral Paradoxic emboli must be thoroughly investigated with
ischemia or non-disabling stroke were examined for the transesophageal echocardiography, especially now that
presence of a carotid bruit. Of these patients, 58% had a new percutaneous methods for closure of occult patent fo-
bruit localized to the ipsilateral carotid artery, 31% had a ramen ovale make this procedure less risky and invasive
carotid bruit involving the contralateral vessel, and 24% than surgery. Other uncommon causes of stroke include
had bilateral carotid bruits. The sensitivity and specificity intracranial tumors, intracerebral hemorrhage (rupture
of a focal bruit to predict high-grade ipsilateral carotid of an aneurysm), central nervous system vasculitis, and
stenosis was 63% and 61%, respectively. The absence of intracranial arteriovenous malformations.
a bruit lowered the pretest probability of a 70% to 99%
carotid stenosis from 52% to 40%. Although carotid artery atherosclerosis is the most
common cause of extracranial carotid artery stenosis and
In addition to the risk of subsequent cerebrovascular stroke, other causes must be considered. Lacunar infarcts,
events in patients with asymptomatic carotid bruits, the
incidence of coronary artery disease and coronary mortal- Table 19.3 Causes of Cerebrovascular Ischemia or Infarction
ity in this patient group is much higher than that of the
general population. One landmark study of 506 patients Thrombosis due to atherosclerosis
with extracranial carotid artery disease and symptomatic Embolization
or asymptomatic bruits showed that approximately 35% Hemorrhage
had severe coronary artery disease that required revascu- Rupture of intracranial aneurysm or arteriovenous malformation
larization or that had progressed to an inoperable status. Intracranial infection (i.e., meningitis)
Cerebrovascular arteritis
The prevalence of severe coronary artery disease in Cerebral venous thromboembolism
patients with symptomatic and asymptomatic carotid ar- Hypercoagulability
tery disease translates into increased mortality rates. In a Carotid artery dissection
study of 444 men with asymptomatic carotid artery steno- Moyamoya disease
sis (mean follow-up, 4 years), the mortality rate was 37%. Fibromuscular dysplasia of the internal carotid artery
Of these deaths, 61% were due to coronary artery disease. Complicated migraine
Multivariate analysis showed that diabetes mellitus, ab- Lacunar infarcts
normal electrocardiography findings, and the presence of
intermittent claudication were associated with increased

214

CHAPTER 19 Carotid Artery Disease and Stroke

embolization, intracranial hemorrhage, and rupture of in- ous carotid dissection tends to occur at age 40 to 50 years.
tracranial aneurysms or arteriovenous malformations are, Although patients may present after a catastrophic event,
in descending order of frequency, important pathologic en- they typically have pain on one side of the head that is
tities. Some (e.g., traumatic injury to the carotid artery) are accompanied by partial Horner syndrome (ptosis, miosis,
simple to identify on the basis of medical history, physical and anhidrosis). After this “warning” presentation, many
examination, and imaging studies. Other causes are chal- patients (50%-95%) will present with cerebral or retinal
lenging to identify because they may be associated with ischemia. Carotid dissection flaps typically begin distal to
a multitude of symptoms, including acephalgic complex the carotid bulb.
migraine and atypical manifestations of epilepsy. FMD of
the internal carotid artery and spontaneous carotid artery In the appropriate clinical scenario, diagnostic tests are
dissection are two vascular conditions that may mimic recommended. The initial diagnostic algorithm begins
cerebral ischemia caused by carotid artery atherosclero- with duplex ultrasonography, which can identify the dis-
sis; these conditions must be understood by the vascular section flap, true and false lumens, and differential flow
medicine specialist. patterns in the two channels. However, if the dissection
is small or begins cephalad to the angle of the mandible,
FMD of the Carotid Artery the dissection may not be detected. Magnetic resonance
angiography (MRA) and, more recently, multidetector
FMD is classified on the basis of the arterial layer in- computed tomography angiography (CTA) are replacing
volved—intima, media, or adventitia. Although many traditional angiography as the imaging methods of choice
physicians consider FMD to affect only the renal arteries, for detecting carotid artery dissection.
the internal carotid artery also is commonly involved.
FMD typically affects women in their 40s. Medial fibro- The conventional treatment of carotid dissection is
plasia is the most common form of FMD and is charac- medical, with anticoagulation therapy (heparin and
terized angiographically as a “string of beads,” in which warfarin) or antiplatelet therapy. A meta-analysis did
the “beads” are larger in diameter than the normal artery. not prove the superiority of one regimen over the other.
FMD usually affects the mid and distal segments of the However, most physicians tend to offer anticoagula-
artery. Patients may present with a myriad of symptoms tion therapy initially. If symptoms resolve, antiplatelet
such as headache, pulsatile tinnitus, and vague symptoms therapy replaces anticoagulation therapy after 3 to 6
that do not commonly reflect true cerebral ischemia. In months; antiplatelet therapy is used for a longer course
addition, if a cervical bruit is identified during a routine (potentially lifelong). Revascularization with surgery or
physical examination, CDUS may be used to evaluate endovascular therapy currently is reserved for patients
it, which may show turbulence with an increase in peak with persistent or recurrent symptoms of ischemia de-
systolic velocities in the mid and distal internal carotid spite adequate anticoagulation.
artery.
• Spontaneous dissection of the carotid arteries is the sec-
The natural disease course of medial fibroplasia of the ond most common cause of stroke in younger patients
internal carotid artery is relatively benign. Some suggest
reassurance and no therapy for incidentally discovered • Conventional treatment of carotid dissection includes
carotid FMD. For patients with symptoms that may be anticoagulation therapy (heparin and warfarin) or an-
attributable to carotid FMD, antiplatelet therapy with tiplatelet therapy
aspirin is recommended. No data are available for other
antiplatelet agents (ticlopidine, clopidogrel, long-acting Risk Factors for Stroke and Carotid Artery
dipyridamole, and aspirin). For symptomatic lesions Disease
that do not respond to antiplatelet therapy, percutaneous
therapy (carotid artery angioplasty) usually is preferred Control of several modifiable risk factors, in particular hy-
over surgical graduated intraluminal dilatation, despite pertension, diabetes mellitus, dyslipidemia, and tobacco
the lack of comparative trials. Physicians must recall that use, is integral to stroke prevention. For example, patients
an association between carotid FMD and intracranial an- with diabetes mellitus have twice the risk of stroke and
eurysms is often noted. carotid artery disease than patients without diabetes mel-
litus. Similarly, smokers have increased risk for all stroke
Carotid Artery Dissection subtypes; the relative risk is 2.58 when compared with pa-
tients who have never smoked. Low levels of high-density
Spontaneous dissection of the carotid or vertebral arteries lipoprotein cholesterol and a high ratio of total to high-
accounts for only 2% of all strokes, but it is the second most density lipoprotein cholesterol are risk factors for carotid
common cause of stroke in younger patients. Spontane- atherosclerosis, although hypercholesterolemia is not a
strong independent risk factor for stroke.

215

Vascular Medicine and Endovascular Interventions

As many as 60% of all strokes are attributable to hy- • Carotid atherosclerosis risk increases as the number of
pertension, and the incidence and mortality rates increase stroke risk factors (hypertension, diabetes mellitus, to-
with blood pressures above 110/75 mm Hg. An estimated bacco use, and dyslipidemia) increases
two-thirds of stroke risk in the general population is at-
tributable to hypertension. Clinical trials of antihyperten- Diagnostic Tests for Carotid Artery
sive therapy have shown that even a modest decrease in Disease
blood pressure decreases the incidence of stroke. Many
prospective trials suggest a linear relationship between Intra-arterial digital subtraction angiography is the diag-
blood pressure and stroke risk, but other (largely cohort) nostic standard for identifying carotid artery stenosis and
studies have suggested a J-shaped phenomenon that measuring its severity. Although serious complications
shows increased stroke rates at the very high and very low are associated with cerebral arteriography, in skilled cen-
blood pressure levels. An evaluation of 7 meta-analyses of ters, these risks approach 1% morbidity and 0.1% mortal-
randomized trials suggests that the relationship is linear ity. However, this test is an impractical means of estab-
with a 31% risk reduction with every 10-mm Hg decrease lishing the presence of carotid artery stenosis because it
in systolic blood pressure. is invasive and cost prohibitive.

Atherosclerosis of the extracranial carotid arteries is a If the patient has ischemic symptoms, computed to-
leading cause of stroke. Hypertension promotes the de- mography (CT) of the brain should be performed initially;
velopment of atherosclerosis at the bifurcation of the com- CT may show hemorrhagic infarction, subarachnoid hem-
mon carotid artery into the internal and external carotid orrhage, tumor, intracranial aneurysm, and arteriovenous
arteries. Carotid atherosclerosis generally is most severe malformation. Magnetic resonance imaging of the brain is
within 2 cm of the common carotid artery bifurcation and a more sensitive indicator of small and hyperacute infarcts
often involves the posterior wall of the vessel. and necrosis caused by the ischemia. For patients with a
cervical bruit or at high risk of carotid stenosis, CDUS,
In a series of 3,602 patients, the presence of hyperten- MRA, and CTA are reliable and non-invasive tests.
sion predicted the severity of carotid atherosclerosis, as
evaluated by high-resolution B-mode ultrasonographic • CDUS, MRA, and CTA are the preferred non-invasive
assessment of intimal-medial thickness, carotid plaque diagnostic tests for carotid artery disease
score, and maximal percentage of stenosis. The presence of
hypertension may be as important as plaque morphology Carotid Duplex Ultrasonography
and severity for prediction of neurologic events. A pro-
spective study of serial carotid ultrasonography showed CDUS uses B-mode and Doppler ultrasonography to de-
that hypertension, plaque echolucency, and lesion pro- tect focal increases in systolic and end-diastolic velocities,
gression predicted patient symptoms. which may be used to indicate moderate and severe ex-
tracranial carotid artery stenosis. State-of-the-art centers
Patients with diabetes mellitus are twice as likely to use a combination of gray-scale, color-flow, Doppler, and,
have a stroke. Tobacco use is a well-documented risk fac- in certain circumstances, “power Doppler” techniques to
tor for cerebrovascular ischemia. Use of oral contracep- perform a complete CDUS examination. The gray-scale
tives and active tobacco use together form an important image provides information about the location of the
combination of risk factors that may result in hyperco- major extracranial carotid arteries (common carotid, in-
agulability. ternal carotid, external carotid, and vertebral arteries). It
also assesses plaque composition (heterogeneous [fibrous]
Carotid atherosclerosis risk increases as the number of plaque and homogeneous [fatty] plaque) and plaque ul-
risk factors for stroke (e.g., hypertension, diabetes melli- ceration. The color-flow image facilitates rapid localization
tus, tobacco use, and dyslipidemia) increases. One study of the arterial stenosis, but the Doppler evaluation most
of almost 4,000 patients showed that the incidence of mild reliably defines the presence and severity of carotid artery
carotid stenosis (25%-49%) increased from 2.4% in patients stenosis. However, inaccurate determinations of the sever-
without risk factors to 18.6% in patients with three risk ity of stenosis may result from improper CDUS procedure.
factors. Similarly, the incidence of severe (≥50%) carotid CDUS is the ideal modality for evaluating the adequacy of
stenoses increased from 0.6% for patients with no stroke revascularization over time. Some centers use transcranial
risk factors to 5% for patients with three risk factors. Doppler in conjunction with CDUS to determine collateral
pathways in the intracranial circulation. In addition, cer-
• Approximately 60% of all strokes are attributable to hy- ebral vasospasm is well visualized with this technique.
pertension

• Even a modest decrease in blood pressure decreases the
incidence of stroke (a 10-mm Hg decrease in systolic
blood pressure is associated with a 31% risk reduction)

216

CHAPTER 19 Carotid Artery Disease and Stroke

Magnetic Resonance Angiography Treatment of Carotid Artery Disease With
or Without Cerebral Ischemia
MRA uses the energy generated by controlled proton
shifts in an electromagnetic field to produce a three-di- Medical Treatment of Carotid Artery Disease:
mensional image of the carotid artery bifurcation, which Stroke Prevention
can be used to detect carotid artery stenoses. High-quality
MRA requires administration of a contrast agent, com- Aggressive risk-factor intervention is the cornerstone of
monly gadolinium, via a peripheral venous catheter. Ac- any treatment for carotid artery disease. Treatment of hy-
curacy of MRA is less operator-dependent than Doppler pertension, even for patients with mildly elevated blood
ultrasonography. However, interpretation of the source pressure, decreases the risk of stroke. In a meta-analysis of
images and image postprocessing are important. Refor- hypertension treatment trials, an average decrease in blood
matted images do not determine stenosis severity accu- pressure of only 5.8 mm Hg resulted in a 43% decrease in
rately. In fact, without gadolinium, the two-dimensional the incidence of stroke. Arecent meta-analysis of seven ran-
time-of-flight images overestimate stenoses (moderate domized, secondary-prevention trials of antihypertensive
stenoses appear severe, severe stenoses appear occluded). therapy for patients with previous stroke or TIA confirmed
In addition, patients who are severely ill, morbidly obese, that the prevention of vascular events was associated with
or claustrophobic, or who have an implanted cardiovert- the magnitude of blood pressure reduction.
er-defibrillator or pacemaker should not undergo MRA
evaluation. Data assessing the benefit of antihypertensive therapy
in patients with carotid stenosis are limited, partially
CDUS and MRA have similar reported sensitivities because of concerns about blood pressure reduction in
(83%-86%) and specificities (89%-94%). A meta-analysis of patients with severe carotid stenosis. One meta-analysis
these imaging modalities showed that they have the same evaluated patients from two major randomized carotid
capacity to detect complete carotid artery occlusion and endarterectomy trials and one major randomized trial of
stenosis greater than 70%. Current algorithms commonly antiplatelet therapy. Among medically treated patients
use the results of two imaging modalities to determine the with symptomatic carotid atherosclerosis, elevated blood
anatomic options for carotid revascularization. pressure was associated with increased stroke risk. In
patients with bilateral carotid stenoses of 70% or greater,
Multidetector CTA however, those with lower systolic blood pressure had
more events. Although the results were interesting, the
More recently, multidetector CTA has been used to iden- study was observational and had only a small number
tify patients with carotid artery stenosis. Early experience of absolute events. Because of these limitations, it is not
with first-generation devices showed a sensitivity of 85% possible to make definitive recommendations to avoid
to detect stenosis of 70% to 99%, with a specificity of 93%. lowering blood pressure in patients with bilateral carotid
Calcification at the area of significant stenosis impairs atherosclerosis. If blood pressure is lowered, it should be
image interpretation. In addition, CTA is not practical for done so cautiously. The antihypertensive agent of choice
serial surveillance of a carotid stenosis because the test re- for patients with carotid atherosclerosis should not differ
quires considerable external beam radiation and adminis- from published guidelines.
tration of an iodinated contrast medium.
Antiplatelet therapy, specifically aspirin (81-325 mg/d),
Invasive Arteriography results in a 25% relative risk reduction compared with pla-
cebo. The CAPRIE (Clopidogrel vs Aspirin in Patients at
Angiography is considered the gold standard for assessing Risk of Ischaemic Events) trial did not show a decrease in
cerebrovascular arteries. Given the progressive improve- stroke risk with clopidogrel when compared with aspirin
ment in non-invasive imaging techniques, cerebrovascu- alone. Long-acting dipyridamole added to aspirin for sec-
lar arteriography is infrequently required as a diagnostic ondary stroke prevention has some benefit. Combination
test. However, if two non-invasive tests performed by antiplatelet therapy with aspirin and clopidogrel, which
expert laboratories have discordant findings, angiogra- is effective for patients with acute coronary syndromes,
phy is indicated. The major drawback of invasive angi- recently was shown to offer no decrease in the rate of neu-
ography is the risk of adverse events associated with the rologic events and had a significant increase in serious
procedure. In the Asymptomatic Carotid Atherosclerosis hemorrhagic events when compared with aspirin alone.
Study (ACAS) trial, a 1.2% risk of stroke was attributable No data support the use of anticoagulation therapy with
to angiography. warfarin to decrease the risk of stroke in patients who do

217

Vascular Medicine and Endovascular Interventions

not have atrial fibrillation or another indication for sys- comes in 3,120 patients who were randomly assigned to
temic anticoagulation. receive medical therapy or CEA. In this series, the risk of
perioperative stroke and death was 3.1%. The 5-year risk
Large studies of lipid-lowering therapy, predominantly of stroke was decreased from 11% for medically treated
with statins (HMG-CoA reductase inhibitors), have shown patients to 3.8% for those undergoing CEA (P<.001).
significant rates of stroke reduction. Patients with athero-
sclerotic carotid artery disease should receive lipid-low- One study examined mortality rates for all Medicare
ering therapy to achieve National Cholesterol Education patients (N=113,300) who underwent CEA during the
Program guideline levels. same period in which the randomized CEA trials were
conducted. This study reported a 30-day mortality rate
• Antiplatelet therapy with aspirin (81-325 mg/d) results threefold greater than that reported in the randomized
in a relative risk reduction when compared with pla- prospective trials. This raises a question about whether
cebo the rates of perioperative stroke and death shown in pro-
spective randomized multicenter trials can be achieved in
• The CAPRIE trial showed no reduction in stroke risk community-based settings.
with clopidogrel when compared with aspirin alone
• For symptomatic patients with high-grade carotid ste-
• Combination antiplatelet therapy with aspirin and nosis (70%-90%), CEA is superior to medical therapy for
clopidogrel shows no decrease in neurologic event rates prevention of stroke
but shows a significant increase in serious hemorrhagic
events when compared with aspirin-only therapy • For asymptomatic patients with 60%-99% carotid ste-
nosis, CEA is more effective than medical therapy for
• No data support the use of warfarin to decrease the risk stroke prevention
of stroke in patients without atrial fibrillation or other
conditions requiring systemic anticoagulation Percutaneous Therapy

• Lipid-lowering therapy, predominantly with statins, Carotid artery stent (CAS) placement recently has become
decreases stroke rate an acceptable alternative for selected patients at increased
risk of serious complications during CEA. The procedure
Surgical Therapy used in one large-scale multicenter prospective trial (com-
paring CAS placement with CEA in high-risk patients)
Carotid endarterectomy (CEA) is well established as the and in many industry-sponsored prospective multicenter
surgical procedure of choice for treatment of extracranial single-arm registries involves a self-expanding metallic
carotid artery disease. The preferred method of perform- alloy stent and a distal embolic protection device (EPD).
ing CEA is debated; major points of contention include EPDs capture the debris potentially released during stent
patching the vessel versus primary closure, use of shunt- placement and prevent embolization of particulate matter
ing during the procedure, standard endarterectomy ver- to the brain. Carotid stenting currently is recommended as
sus eversion endarterectomy, and use of regional versus an alternative to CEA for patients with anatomic or medi-
general anesthesia. The procedure is safe and effective cal comorbid conditions that place them at high surgical
when performed by a highly skilled and experienced sur- risk (Table 19.4).
geon. Most professional medical organizations agree that
the perioperative morbidity and mortality rates for CEA The Carotid and Vertebral Artery Transluminal Angio-
are 3% for asymptomatic patients, 6% for symptomatic pa- plasty Study (CAVATAS) was a prospective trial of 504
tients, and 10% for patients with a restenotic CEA site. patients randomly assigned to undergo CEA (n=253) or
carotid angioplasty (n=251, only 26% of whom received a
The NASCET and the European Carotid Surgery Trial stent). Using an end point of disabling stroke or death by
showed that CEA was superior to medical therapy for the 30 days, no difference was measured between the angio-
prevention of stroke in symptomatic patients with high- plasty (10%) and surgical groups (9.9%).
grade carotid stenosis (70%-99%), despite a 6% incidence
of perioperative stroke and death. When compared with The first large prospective multicenter trial to compare
the best medical therapy, CEA also showed clinically sig- CEA to CAS with EPD in high-risk patients was the SAP-
nificant benefits in symptomatic patients with moderate- PHIRE (Stenting and Angioplasty with Protection in Pa-
severity stenosis (50%-69%). tients at High Risk for Endarterectomy) study. Patients
were randomly assigned to receive a CAS with distal
For patients with asymptomatic carotid stenosis of 60% protection (n=159) or to undergo CEA (n=151). Other pa-
to 99% and acceptable perioperative risk status, evidence tients who were too high risk for CEA and had CAS place-
suggests that CEA is more effective than medical therapy ment (n=406) or who were not candidates for CAS and
for prevention of stroke. This was first shown in the ACAS underwent CEA (n=7) were followed up in a prospective
trial, in which the 5-year absolute risk reduction was
slightly greater than 1% per year. The prospective multi-
center Asymptomatic Carotid Surgery Trial reported out-

218

CHAPTER 19 Carotid Artery Disease and Stroke

Table 19.4 Comorbid Conditions of Patients With High Surgical Risk Questions

Anatomic condition 1. Which test is most likely to determine the cause of left-
High cervical lesion that would require jaw disarticulation for CEA sided hemiplegia in a 63-year-old right-handed man?
Ostial common carotid artery lesion that would require median sternotomy a. Erythrocyte sedimentation rate
Contralateral internal carotid artery occlusion b. Transcranial Doppler ultrasonography
Prior neck irradiation c. Brain CT
Restenosis of prior CEA site d. Transesophageal echocardiography
Contralateral laryngeal nerve palsy e. Hemoglobin A1c
Tracheal stoma
2. What is the most important clue from the history or
Medical condition physical examination for determining the need for and
Class III or IV congestive heart failure method of revascularization of a carotid artery?
Left ventricular ejection fraction <30% a. The finding of a cervical bruit
Unstable angina pectoris b. The absence of a temporal artery pulse
Recent myocardial infarction c. Evidence of tendinous xanthomas on the olecranon
Severe chronic obstructive pulmonary disease bursa
Need for coronary artery bypass graft surgery d. Classic description of repeated episodes of aphasia
for the previous 24 hours
CEA, carotid endarterectomy. e. The number of pack-years that the patient smoked
cigarettes
single-arm registry. In the randomized group, the primary
(combined) end point was the 30-day incidence of stroke, 3. Which of the following diagnostic algorithms is most
death, and myocardial infarction and was designed to correct?
assess non-inferiority of CAS to CEA. The incidence rate a. Cervical bruit→Digital subtraction arteriography
was lower for the CAS group (4.8%) than for the CEA b. Cervical bruit→CDUS→Digital subtraction arteriog-
group (9.6%), but the difference was not statistically sig- raphy
nificant (P=.14). For registry patients, the 30-day incidence c. Symptoms of cerebral ischemia→Diffusion-weighted
was 7.8% for those who received a CAS and 14.7% for magnetic resonance imaging
those who underwent CEA. The surgical group also had d. Symptoms of cerebral ischemia→Two-dimensional
an excess of cranial nerve injuries (5.3%), versus no such time-of-flight MRA
injuries in the stent group. The 1-year combined end point e. Cervical bruit→MRA→Multidetector CTA→Digital
was 11.9% for the CAS group and 19.9% for the CEA group subtraction arteriography
(P<.05).
4. A 61-year-old woman has a left systolic and diastolic
The Carotid Revascularization Using Endarterectomy cervical bruit. Which of the following would most likely
or Stenting Systems phase 1 study enrolled 397 patients explain this physical examination finding?
who either were symptomatic and had greater than 50% a. An 80%-99% ipsilateral internal carotid artery steno-
carotid artery stenosis (n=128) or were asymptomatic and sis with a patent contralateral internal carotid artery
had greater than 75% stenosis (n=269). Treatment was b. Mitral stenosis
solely at the discretion of the investigator; 254 patients c. Left ventricular ejection fraction of 20%
were treated with endarterectomy, and 143 underwent d. An ipsilateral jugular vein thrombosis
CAS placement using a distal EPD. No difference in com- e. An 80%-99% ipsilateral internal carotid artery steno-
bined death and stroke rates was observed between the sis with a contralateral “string sign”
two groups at 1 year (CEA, 13.6%; CAS, 10.0%).
5. Which treatment strategy is optimal for a 77-year-old
The Carotid Revascularization with Endarterectomy man with a 90% right internal carotid artery stenosis,
versus Stent Trial, sponsored by the National Institutes transient left-arm hemiplegia, and a contralateral left
of Health, currently is enrolling patients, and the results internal carotid artery occlusion?
of several prospective single-arm registries are being re- a. Antihypertensive therapy, aspirin, and statins
leased. Controversy persists among investigators and b. Antihypertensive therapy, aspirin, clopidogrel, and
clinicians about the safety and efficacy of CAS with EPD statins
in non–high-risk asymptomatic patients with moderate c. Antihypertensive therapy, aspirin, clopidogrel, stat-
or severe carotid artery stenosis. The industry-sponsored ins, and CAS
ACT 1 Trial (Carotid Stenting vs Surgery of Severe Carotid
Artery Disease and Stroke Prevention in Asymptomatic 219
Patients) has begun enrollment, and several other trials
are in the planning stages. These studies may provide data
on the large population of asymptomatic patients with ca-
rotid artery stenosis.

Vascular Medicine and Endovascular Interventions

d. Antihypertensive therapy, aspirin, clopidogrel, stat- Erratum in: Circulation. 2004;110:763.
ins, and CEA Halliday A, Mansfield A, Marro J, et al, MRC Asymptomatic Ca-

e. Antihypertensive therapy, aspirin, statins, and CEA rotid Surgery Trial (ACST) Collaborative Group. Prevention
after 6 weeks of observation of disabling and fatal strokes by successful carotid endarterec-
tomy in patients without recent neurological symptoms: ran-
Suggested Readings domised controlled trial. Lancet. 2004;363:1491-502. Erratum
in: Lancet. 2004;364:416.
Bock RW, Gray-Weale AC, Mock PA, et al. The natural history of Hertzer NR, Young JR, Beven EG, et al. Coronary angiography
asymptomatic carotid artery disease. J Vasc Surg. 1993;17:160- in 506 patients with extracranial cerebrovascular disease. Arch
9. Intern Med. 1985;145:849-52.
McGovern PG, Burke GL, Sprafka JM, et al, The Minnesota Heart
CAPRIE Steering Committee. A randomised, blinded, trial of Survey. Trends in mortality, morbidity, and risk factor levels
clopidogrel versus aspirin in patients at risk of ischaemic for stroke from 1960 through 1990. JAMA. 1992;268:753-9.
events (CAPRIE). Lancet. 1996;348:1329-39. North American Symptomatic Carotid Endarterectomy Trial
Collaborators. Beneficial effect of carotid endarterectomy in
CaRESS Steering Committee. Carotid Revascularization Using symptomatic patients with high-grade carotid stenosis. N Engl
Endarterectomy or Stenting Systems (CaRESS) phase 1 clinical J Med. 1991;325:445-53.
trial: 1-year results. J Vasc Surg. 2005;42:213-9. Sauve JS, Thorpe KE, Sackett DL, et al, The North American
Symptomatic Carotid Endarterectomy Trial. Can bruits distin-
CAVATAS Investigators. Endovascular versus surgical treatment guish high-grade from moderate symptomatic carotid steno-
in patients with carotid stenosis in the Carotid and Vertebral sis? Ann Intern Med. 1994;120:633-7.
Artery Transluminal Angioplasty Study (CAVATAS): a ran- Wennberg DE, Lucas FL, Birkmeyer JD, et al. Variation in ca-
domised trial. Lancet. 2001;357:1729-37. rotid endarterectomy mortality in the Medicare population:
trial hospitals, volume, and patient characteristics. JAMA.
Executive Committee for the Asymptomatic Carotid Atheroscle- 1998;279:1278-81.
rosis Study. Endarterectomy for asymptomatic carotid artery Yadav JS, Wholey MH, Kuntz RE, et al, Stenting and Angioplasty
stenosis. JAMA. 1995;273:1421-8. With Protection in Patients at High Risk for Endarterectomy
Investigators. Protected carotid-artery stenting versus endar-
Grundy SM, Cleeman JI, Merz CN, et al, National Heart, Lung, terectomy in high-risk patients. N Engl J Med. 2004;351:1493-
and Blood Institute, American College of Cardiology Founda- 501.
tion, American Heart Association. Implications of recent clini-
cal trials for the National Cholesterol Education Program Adult
Treatment Panel III guidelines. Circulation. 2004;110:227-39.

220

20 Patient Selection and Diagnosis for
Endovascular Procedures

Christopher J. White, MD

Introduction Currently, EI is considered a safe and effective means of
restoring blood flow in selected patients, and if a patient
The concept of non-surgical revascularization was intro- is a candidate for either open or percutaneous surgery, EI
duced by Charles Dotter and was further advanced with is considered the therapy of choice.
the development of balloon dilation catheters by Andreas
Gruntzig. Endovascular intervention (EI) has evolved General Evaluation
over the past 25 years in a stepwise fashion. Early EI
procedures used bulky equipment, required large access For all patients being considered for possible peripheral
catheters, and were limited to balloon dilation. Procedures revascularization, the history should be directed at their
were initially offered only to patients who were not surgi- chief concern; patients also should undergo a general
cal candidates. As the catheters evolved and developed medical evaluation with attention directed to the status of
lower profiles, they were used in more anatomic locations, the entire cardiovascular, pulmonary, and renal systems.
including the upper and lower extremities, renal and me- Atherosclerosis is a systemic disease; therefore, risk factor
senteric circulations, and the supraclavicular arteries. assessment, screening tests for cardiovascular diseases,
and optimization of medical therapy are required.
Durability, or prolonged vascular patency, has tradi-
tionally been better with surgical procedures, but recently A cardiovascular history establishes the presence of
stents have been shown to be better in many vascular atherosclerotic risk factors, including the presence of other
distributions. The use of stents has shifted the balance in common manifestations of atherosclerosis such as cer-
treatment away from conventional surgical therapies and ebrovascular, renal, cardiac, and lower extremity symp-
toward endovascular therapy. There is currently a better toms. A complete physical examination should include all
understanding of differences in restenosis rates by ana- pulses, listening for bruits over the carotids, palpation of
tomic region, which also affects treatment selection. For the abdominal aorta and common femoral arteries, exami-
example, the superficial femoral artery, the renal artery, nation of the legs and feet, and auscultation of the heart
and the internal carotid artery all have nominal diameters and lungs.
of approximately 6 mm, yet the restenosis rates for these
three vascular beds, with the same stents placed, are mark- General laboratory data required before planning an
edly different. Clearly, the intimal hyperplastic response EI include electrocardiography, serum electrolytes, fast-
differs among vascular beds and should be factored into ing blood sugar, renal function studies, complete blood
the patient’s treatment plan. count, coagulation status (international normalized ratio,
prothrombin time, activated partial thromboplastin time),
• The superficial femoral, renal, and internal carotid ar- and stool Hemoccult. If the patient has active lung disease,
teries all have nominal diameters of approximately 6 chest radiography and pulmonary function testing are ap-
mm, but the restenosis rates for all three vascular beds, propriate.
with the same stents placed, are markedly different
Standard premedication before planned EI includes
© 2007 Society for Vascular Medicine and Biology aspirin therapy (81-325 mg daily). The use of additional
antiplatelet agents (clopidogrel or ticlopidine) is optional;
however, they are frequently used for carotid and cer-
ebrovascular interventions. No objective evidence has

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Vascular Medicine and Endovascular Interventions

shown that the use of these more expensive therapies im- • Conventional open surgery remains the treatment of
proves procedural success or decreases complications, as choice for patients at low to moderate surgical risk who
has been shown for coronary artery intervention. require carotid endarterectomy

• Proper planning for EI requires appropriate history, • The efficacy of EI for long (≥10 cm) occlusions or diffuse
physical examination, and general laboratory data stenotic disease is debated

• Standard premedication before EI includes aspirin ther- • In experienced centers, conventional surgery is reserved
apy (81-325 mg/d) for patients who are not candidates for EI or in whom
attempted EI has failed
• Additional antiplatelet agents (clopidogrel or ticlopi-
dine) are optional; these therapies are not proven to • Clinical equipoise exists between open surgery and
increase procedural success or decrease complications endovascular therapy for abdominal aortic aneurysm
repair

Selection Criteria Anatomic Criteria

Patient Selection Several anatomic criteria are important for choosing
between EI and open surgery for a given patient. These
Patient selection for EI depends on both anatomic and include the ability to gain vascular access to the target
functional criteria. In general, the selection of patients for lesion, a reasonable likelihood of crossing the lesion with
surgical revascularization and EI are similar, although a a guidewire, and the expectation that an angioplasty
lower threshold for symptom limitations is often accept- catheter or device can be advanced to the lesion to suc-
ed for EI of lower extremity lesions. Elderly patients and cessfully recanalize it. A favorable procedural result is
those with severe medical comorbid conditions (cardio- more likely in stenoses than occlusions, in larger-diam-
pulmonary disease, diabetes mellitus, renal insufficiency) eter than smaller-diameter vessels, in discrete rather
are preferentially treated with EI versus open surgery. than longer (≥3 cm) lesions, and in patients with milder
rather than more severe symptoms. Anatomic criteria
Conventional open surgery remains the treatment of also include the objective assessment of lesion severity.
choice for patients at low to moderate surgical risk who Severity may be assessed with invasive angiography or
may require carotid endarterectomy. Unless such patients non-invasively with magnetic resonance angiography
are enrolled in a clinical trial, they should not be offered (MRA), computed tomography angiography (CTA), or
carotid stenting as an alternative to carotid endarterec- duplex imaging.
tomy. In no other vascular bed is open surgery clearly the
treatment of choice, although conventional surgery is an The availability of endovascular stents (balloon and
attractive option in many circumstances. For example, self-expandable) has significantly extended the anatomic
in patients with limb-threatening ischemia or acute limb subset of patients who can be considered as candidates
ischemia who are not suitable candidates for EI, open sur- for percutaneous revascularization, particularly for those
gery is the treatment of choice. with longer lesions and occlusions. The limiting factor for
non-surgical revascularization of the aortoiliac vessels is
There is debate in the literature regarding the efficacy the ability to pass a guidewire across the lesion. Regard-
of EI for patients with long (≥10 cm) occlusions or diffuse less of the balloon dilation result, the option of stent place-
stenotic disease. Some of these patients may be better ment offers a reliable and reproducible method to recanal-
served by open surgery than EI, but attempted EI rarely, ize these vessels.
if ever, compromises the success of a later approach with
open surgery. For this reason, in experienced centers, con- Anatomic criteria for aortic arch vessel and supracla-
ventional surgery is reserved for patients who are not can- vicular procedures must take into account the tortuosity,
didates for EI or in whom attempted EI has failed. calcification, and embolic potential of the aortic arch and
arch vessels. A severely unwound aortic arch or tortuous
Clinical equipoise—collective professional uncertainty arch vessels may present a high risk for complications
regarding treatment—seems to exist between open sur- with an endovascular approach and can be approached
gery and endovascular therapy for abdominal aortic more safely with conventional surgery.
aneurysm repair. Decisions regarding individual patient
therapy should be based on the treating physician’s ex- • Anatomic criteria to be considered for aortic arch vessel
perience, the patient’s preference, the patient’s comorbid and supraclavicular procedures must include the tortu-
conditions, and the suitability of the lesion for endograft osity, calcification, and embolic potential of the aortic
repair. arch and arch vessels

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CHAPTER 20 Patient Selection for Endovascular Procedures

When considering renal or mesenteric artery revasculari- sure gradients. Walking distance on a treadmill is another
zation, the status of the abdominal aorta must be taken way to objectively assess the functional limitation due to a
into account. A very diseased, shaggy, abdominal aorta lower extremity vascular stenosis. Subjective assessments
may dictate specific endovascular approaches, such as the include abdominal discomfort after meals, leg cramping
“no-touch” technique. A history of atheroembolization with walking, or resting leg pain at night.
should be considered a contraindication to renal inter-
vention. Finally, if the vessels arise from the aorta with When selecting patients for revascularization therapy,
an acute downward orientation, an upper extremity ap- it is appropriate in many cases to require that the patient
proach (axillary, brachial, or radial) is indicated. had previous failure of conservative therapy (exercise,
pharmacologic intervention, risk factor modification) be-
In-Stent Restenosis fore subjecting the patient to the risks of either surgery or
EI.
An interesting phenomenon is the differential rate of
in-stent restenosis related to intimal hyperplasia in differ- • It is appropriate to require previous failure of conserva-
ent vascular beds. At best, the rate of restenosis for super- tive therapy before considering revascularization ther-
ficial femoral artery lesions is between 30% and 50%, for apy for a patient
renal artery lesions is 10% to 15%, and for carotid artery
lesions is less than 5%. It is generally assumed that in-stent • Before being considered for percutaneous or surgical
restenosis merits at least one attempt at repeat percutane- revascularization therapy, symptomatic patients with
ous therapy before referral for surgical therapy. However, anatomically suitable lower extremity lesions should
restenosis in the superficial femoral artery is much more have either:
likely to be resistant to percutaneous therapies and more • Failure of a reasonable attempt at medical therapy for
likely to benefit from surgical bypass. lifestyle-limiting claudication
• Demonstrated critical limb ischemia
Vascular Access
Patients with symptomatic lower extremity lesions that
The initial consideration for an EI is the choice of vascular are anatomically suitable should have prior failure of a
access site. The target lesion dictates the most desirable reasonable attempt at medical therapy for lifestyle-limit-
arterial access site. For example, for carotid lesions, retro- ing claudication or demonstration of critical limb ischemia
grade common femoral access is preferred, because gain- before being considered candidates for percutaneous or
ing catheter access to the aortic arch vessels is generally surgical revascularization therapy. If a patient presents for
easier from below them. For mesenteric lesions, brachial percutaneous intervention with limb-threatening ischemia
access is often chosen to take advantage of the cephalic (gangrene, non-healing ulcer, or rest pain), multilevel dis-
orientation of these vessels arising from the abdominal ease is likely to be present. Simply improving “inflow”
aorta. Other considerations include the presence of oc- without addressing more distal flow-limiting lesions may
clusive disease or a dialysis fistula, which may limit the not solve the problem. However, for patients with moder-
choice of access sites. ate to severe symptomatic carotid artery stenoses, a trial of
medical therapy before revascularization is not appropri-
Contraindications ate. Based on level I clinical trial evidence, these patients
should be revascularized.
Relative anatomic contraindications to EI include lesions
likely to generate atheroemboli and lesions that are undi- • Multilevel disease is likely to be present in a patient with
latable because of calcification. Relative clinical contrain- limb-threatening ischemia; simply improving “inflow”
dications include any instances in which the risks of the by percutaneous intervention without addressing distal
procedure outweigh the potential benefits. flow-limiting lesions may not solve the problem

Functional Criteria Asymptomatic patients usually are not considered candi-
dates for revascularization because the potential benefit
The functional significance of peripheral vascular stenosis does not justify the known procedural risks, but asymp-
is reflected by the associated symptoms. Functional crite- tomatic patients may be considered for revascularization
ria may be objective or subjective. Examples of objective in specific instances. The first such indication is moderate
assessments of ischemia include the ankle-brachial index, to severe carotid artery stenosis (≥60%) in an asymptom-
duplex velocity measurements, and translesional pres- atic patient; level I evidence supports revascularization
of these patients. If the carotid stenosis is 80% or greater
and the patient is at increased risk for carotid artery end-

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Vascular Medicine and Endovascular Interventions

arterectomy, randomized trial evidence suggests that Invasive Testing
carotid stent placement with an embolic protection device
is indicated. Based on the natural history of carotid artery Invasive testing includes physiologic or functional test-
lesions, revascularization of the asymptomatic carotid ste- ing. Physiologic testing includes the hemodynamic
nosis, in experienced hands, is the correct procedure. measurement of translesional pressure gradients and the
determination of fractional flow reserve. Occasionally, a
Another circumstance in which an asymptomatic steno- borderline resting gradient is augmented with a vasodila-
sis or occlusion would be considered for intervention is if tor to amplify the severity of the vascular disease. Invasive
a patient with an asymptomatic iliac lesion requires com- imaging can be done with intravascular ultrasonography
mon femoral artery access for a cardiac procedure. In this or angiography. Typically, invasive testing is reserved for
case, it is appropriate to treat the iliac stenosis. Similarly, patients who meet the minimum criteria for revascular-
if placement of an intra-aortic counterpulsation balloon is ization. In other words, if a patient with claudication has
necessary, it is appropriate to perform femoral or iliac an- been characterized by non-invasive testing and is well
gioplasty to gain access. Finally, in a patient with a femoral compensated with pharmacologic therapy and a walking
or brachial access complication, it would be appropriate to program, invasive angiography is not required because
dilate an asymptomatic stenosis to allow catheter access to there is no indication for revascularization.
treat the access site complication.
Questions
When selecting patients for EIs, it is important to under-
stand any additional condition they have that could affect 1. A patient with poorly controlled hypertension on three
the procedure. This might include diabetes mellitus, renal medications undergoes screening renal Doppler ultra-
insufficiency, a history of contrast reactions, and adverse sonography, which gives inconclusive results. What
anticoagulation status. Appropriate planning and patient would be your next step?
preparation are required in these circumstances. a. Invasive angiography
b. Non-invasive CTA
Diagnostic Assessment c. Non-invasive MRA
d. Radionuclide renal scanning with an angiotensin-
When assessing patients with peripheral vascular disease converting enzyme inhibitor
for revascularization, supportive data in the form of diag-
nostic testing are desirable to confirm a clinical diagnosis. 2. A patient with a systolic blood pressure gradient of
Typically, non-invasive testing is preferred over invasive 50 mm Hg between arms (right>left) is undergoing
testing. Choices include physiologic testing, such as Dop- diagnostic angiography to determine the presence of
pler ultrasonography (duplex) and ankle-brachial index, coronary artery disease. Which of the following would
and anatomic assessment with imaging studies, including most likely necessitate additional angiography of the
ultrasonography, MRA, and CTA. brachiocephalic vessels?
a. Left arm claudication when weight lifting
Non-Invasive Testing b. Planned coronary artery bypass grafting
c. Retrograde left vertebral flow on duplex ultrasonog-
Testing should be directed by clinical information, at- raphy
tempting to confirm a clinical hypothesis based on his- d. Abnormal results of Allen test on the left arm
tory or physical examination data. With the exception of
well-established screening programs in high-risk popula- 3. A patient presents on two medications for recurrent un-
tions (e.g., carotid duplex ultrasonography in coronary controlled hypertension and with ultrasonographic evi-
bypass patients), indiscriminate non-invasive testing is dence of left renal in-stent restenosis. The original stent
discouraged. No single non-invasive test is best overall. placement procedure had been complicated by a small
The selection of the test is based on the preference of the shower of “atheroemboli” to both feet, which resolved
treating physician, patient concerns (e.g., claustrophobia over several weeks without tissue loss. What would be
for MRA, renal function for CTA, obesity for renal ultra- your recommendation now?
sonography), technician skill level, and cost. Generally, a. Angiography and possible re-intervention from the
confirmatory non-invasive testing is not encouraged. If arm
clinical suspicion is high and the non-invasive test is ei- b. MRA/CTA to confirm in-stent restenosis
ther indeterminate or contradictory, invasive testing is
required to answer the question.

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CHAPTER 20 Patient Selection for Endovascular Procedures

c. Add additional medications to control blood pres- Suggested Readings
sure
Barnett HJ, Taylor DW, Eliasziw M, et al, North American Symp-
d. Refer for left renal bypass tomatic Carotid Endarterectomy Trial Collaborators. Benefit of
carotid endarterectomy in patients with symptomatic moder-
4. A 67-year-old man recently had a transient ischemic at- ate or severe stenosis. N Engl J Med. 1998;339:1415-25.
tack secondary to a 75% narrowing of the right internal
carotid artery. Angiography shows an unfavorable type Dotter CT, Judkins MP. Transluminal treatment of arteriosclerotic
3 (unwound, calcified, tortuous) aortic arch. He ex- obstruction: description of a new technic and a preliminary
presses a strong preference for avoiding open surgical report of its application. Circulation. 1964;30:654-70.
therapy. What would be your recommendation?
a. Carotid stent with emboli protection with a direct ca- Executive Committee for the Asymptomatic Carotid Atheroscle-
rotid puncture rosis Study. Endarterectomy for asymptomatic carotid artery
b. Medical therapy with aspirin and dipyridamole stenosis. JAMA. 1995;273:1421-8.
c. Attempt carotid stent placement with femoral access
d. Recommend surgical revascularization Gruntzig A, Hopff H. Percutaneous recanalization after chronic
arterial occlusion with a new dilator-catheter (modification of
5. A 55-year-old board certified vascular surgeon has an the Dotter technique) [German]. (Translated by A Gruntzig.)
MRA showing a severe (>80%) discrete right internal Dtsch Med Wochenschr. 1974;99:2502-11.
carotid artery stenosis. He is asymptomatic, and the
stenosis was found after a carotid bruit was heard dur- Halliday A, Mansfield A, Marro J, et al, MRC Asymptomatic Ca-
ing an insurance-required physical examination. He rotid Surgery Trial (ACST) Collaborative Group. Prevention
understands his treatment options, he is willing to pay of disabling and fatal strokes by successful carotid endarterec-
for any unreimbursed expenses, and he came to you for tomy in patients without recent neurological symptoms: ran-
a carotid stent. What would you do? domised controlled trial. Lancet. 2004;363:1491-502. Erratum
a. Offer him a stent since he is well informed about the in: Lancet. 2004;364:416.
risks and benefits
b. Recommend he have carotid endarterectomy Johnston KW. Balloon angioplasty: predictive factors for long-
c. Offer him aspirin and clopidogrel medical therapy term success. Semin Vasc Surg. 1989;2:117-22.
d. Ask him to return in 3 months for follow-up duplex
ultrasonography North American Symptomatic Carotid Endarterectomy Trial
Collaborators. Beneficial effect of carotid endarterectomy in
symptomatic patients with high-grade carotid stenosis. N Engl
J Med. 1991;325:445-53.

Wilson SE, Sheppard B. Results of percutaneous transluminal an-
gioplasty for peripheral vascular occlusive disease. Ann Vasc
Surg. 1990;4:94-7.

Yadav JS, Wholey MH, Kuntz RE, et al, Stenting and Angioplasty
With Protection in Patients at High Risk for Endarterectomy
Investigators. Protected carotid-artery stenting versus endar-
terectomy in high-risk patients. N Engl J Med. 2004;351:1493-
501.

225

21 Endovascular Techniques I: Catheters and
Diagnostic Angiography

Mark C. Bates, MD, FACC

History proach but was ultimately awarded the Nobel Prize. Sven
Seldinger developed the first percutaneous technique for
The term “catheter” originated from the Greek word “kath- inserting catheters into blood vessels in 1953. In the fol-
eter,” meaning “to send down.” Claude Bernard (a well- lowing years, significant advances in catheter technology
known French physiologist) was credited in the mid 1800s and imaging have shaped the field of modern angiology.
as being the first to use the term “catheter” to describe a
tube used in an animal model to measure cardiac pres- The centuries of pioneering work that have gone into
sures. However, the use of tubular structures to access the catheter development are beyond the scope of this chap-
bladder or blood vessels predated Bernard’s work by thou- ter, but it is important to understand this history and the
sands of years. Sushruta Samhita, an Indian surgical text foundation of knowledge that led to the clinical success
from 1000 BC, reported the insertion of wood tubes smeared we now enjoy.
with liquid butter into the bladder for removal of urine and
management of strictures or installation of medication. Ar- Catheter Characteristics
cheologists in Egypt have discovered evidence to suggest
that doctors circa 400 BC used hollow reeds and brass pipes Terms and Definitions
as means to study heart valve function in cadavers.
– I.D., inner diameter of a catheter—usually measured
The first successful documented medical use of an in- in inches for a guide catheter and in French size for a
travascular catheter in humans was in 1667, when a tube sheath.
was placed in a vessel and used to perform the first docu- – O.D., outer diameter of a catheter—usually measured
mented blood transfusion. In the 1800s a Parisian master in French size. Diagnostic catheters and guides are de-
metal cutter and instrument designer, Joseph-Frederic-Be- scribed by O.D. and sheaths are described by I.D.
noit Charriere, developed the French scale for measuring – Flexibility—an indication of the bending stiffness of
catheter size. French size (F) is synonymous with Char- the material. The flexural modulus is a coefficient of elas-
riere size (CH) and equals one-third millimeter. ticity, which represents the ratio of stress to strain as a
material is deformed under dynamic load.
• 1 F = 1 CH = 0.33 mm—used to describe the outer diam- – Kink resistance—refers to the ability of a tube to with-
eter (O.D.) of a catheter and the inner diameter (I.D.) of stand bending and coiling without deforming or kink-
a sheath ing (a fold in the wall). Kinking weakens the structural
strength of the tube and can also block or slow the trans-
In 1929, Werner Forssmann, after studying the writings of ference of media through the tube. Kink resistance is,
Bernard, advanced a rubber ureteral catheter into the right to a large extent, a function of wall thickness and shore
side of his own heart, performing the first documented hardness.
heart catheterization in a living human. He was ostracized – Lubricity (coefficient of friction)—measures the fric-
initially by the medical community for his unorthodox ap- tional properties or tackiness of a material. A low coeffi-
cient of friction is usually desired in medical applications
© 2007 Society for Vascular Medicine and Biology to minimize bodily trauma and tissue irritation.

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CHAPTER 21 Catheters and Diagnostic Angiography

– Shore hardness—the relative resistance of a material’s rubber are also used, depending on the catheter perform-
surface to indentation by an indenter of specified dimen- ance characteristics desired.
sions under specified load. Shore hardness refers to the
general stiffness of a material. The hardnesses are meas- Catheter Construction
ured according to the Durometer and Rockwell scales.
– Tensile strength—a measure of the force required to Understanding how a catheter is constructed helps in un-
stretch a plastic and the percentage of stretching the derstanding its characteristics and how it will behave in the
plastic can withstand before breaking. Ultimate tensile body. A key advance in catheter design came from Robert
strength is the maximum stress a material withstands at Stevens in the early 1960s—incorporating a metal braid into
the point of rupture. Good tensile strength allows for de- a catheter polymer. This greatly improved torque response
sign of thinner wall thicknesses, which result in smaller and selective catheter performance. Today, many diagnos-
diameters. High tensile strength also aids in ease of cath- tic catheters have a flat or fine wire braid and are labeled
eter insertion. Related to this is “ultimate elongation,” “braided.” The use of a braided catheter may be preferred
which is the total elongation by percentage of a sample in tortuous anatomy or if substantial columnar catheter
at the point of rupture. support is needed. Braiding also increases kink resistance,
– Torque—a measure of force related to the rotational shore hardness, and tensile strength. Although guide cath-
stability of the tube. If rotated at one end, a tube with a eters have multiple layers, most diagnostic catheters are
high degree of torque will rotate at nearly the same ratio made of a single polymer with or without a braid.
at the other (untouched) end. A high degree of torque can
be desirable in invasive applications. Braiding of tubes is • The use of a braided catheter may be preferred for tortu-
a method used to increase torque. ous anatomy or if significant columnar catheter support
– Biocompatibility—the suitability of materials for bio- is needed
medical applications. Tests used to screen for suitable
plastic materials include implants in research animals, The outer layer of the catheter determines lubricity, bio-
injection of resin extracts into animals to detect toxic re- compatibility, and thrombogenicity. For example, cath-
sponses, and tissue culture on resins and resin extracts eters coated with hydrophilic fluoropolymers reduce re-
using mammalian and human cells. Other tests include sistance and improve tracking as the catheter is navigated
hemolysis testing, intracutaneous injection of rabbits, through tortuous or diseased vessels.
systemic toxicity in mice, cell growth inhibition of aque-
ous extracts, and total and extractable heavy metals and Non-Selective Angiography
buffering capability.
– Thrombogenicity—the tendency of an agent to cause Non-selective angiography is performed by placing a
blood clot formation around the invasive area. This is catheter with multiple side holes, a “flush catheter” (Fig.
an adverse phenomenon that can lead to further com- 21.1), into the parent vessel; it usually requires the use of a
plications. In plastics applications, a smooth surface is power injector to obtain diagnostic information regarding
desirable to avoid activation of the clotting mechanism. the vessel and branches. Non-selective power injection
Hydrophilic surfaces are known to prevent absorption of angiography should never be performed with an end-
protein and cells and therefore prevent the blood clotting
immune response. The more hydrophilic the plastic, the
less foreign the material is to the body.

Contemporary Catheter Design and Materials

Catheter Materials Fig. 21.1 Examples of non-selective “flush” catheters. PIG, pigtail; STR,
straight; TR, tennis racket; UNIV, universal.
Early catheters were made from the naturally occurring
materials rubber and latex. Biocompatibility issues and
the lack of coaxial support (column strength) in rubber
and latex led to the use of inert thermoelastic polymers in
the 1950s. One of the most popular catheter materials used
today is nylon, a polyamide resin, which has a very high
melting point and is inert. Other plastics such as poly-
urethane, polyvinyl chloride, polyethylene, and silicone

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Vascular Medicine and Endovascular Interventions

hole catheter because of the inherent risk of inadvertent from the cephalad spray of the pigtail catheter into the
injection into a small side branch or atheromatous plaque. superior mesenteric or celiac system. Occasionally, cra-
Meticulous catheter flushing, beginning with blood with- nial angulation is needed to see the renal ostia in patients
drawal, is important before any forward injection of saline with infrarenal abdominal aortic aneurysmal disease be-
or contrast material. cause of the frequently anterior trajectory of the proximal
neck.
Each catheter has a threshold for maximum contrast in-
jection volume over time. The injection flow rate threshold The pigtail catheter is typically stationed at the level
can be estimated by understanding Poiseuille’s law: of L1 with the image intensifier in the lateral projection
to evaluate the origin of the celiac and mesenteric sys-
Volume flow rate (F) = pressure decrease along the tube tem. One of the most feared complications of abdominal
resistance to flow angiography is inadvertent power injection into the tho-
racic artery and the artery of Adamkiewicz, which re-
Resistance to flow (R) = 8ηL/πr4 sults in permanent paralysis. This serious complication
can be avoided by appropriate positioning of the cath-
F=(P1–P2)πr4/8ηL eter below T12 and being certain that the flush catheter
is freely moving in the aorta before injection of contrast
Where: P1=pressure at entry point; P2=pressure at exit material.
point; r=radius of tube; η=viscosity of fluid; and L=length
of tube. Aortic Arch Angiography

Catheter length and internal radius are important vari- The origin of the great vessels is usually best visualized in
ables in this equation. Side holes in the catheter reduce the LAO projection. The optimum image window can be
the effective catheter length, whereas tapering the tip de- defined by simply shifting the image intensifier in the LAO
creases the effective internal diameter. Changing catheter direction until the foreshortening of the pigtail catheter on
lumen radius has a greater effect on resistance than does fluoroscopy is completely eliminated, which suggests that
changing length because it is a fourth-order variant. For the image intensifier is perpendicular to the arch profile.
example, if a 5F pigtail catheter with a 0.038-in wire lumen With rare exception, selective angiography of the great
is 65 cm long, the maximal flow rate for a power injection vessels should not be performed without first performing
is 33 mL/s. The same catheter with a length of 110 cm has non-selective imaging of the aortic arch so that definition
a maximum flow rate of 26 mL/s. If the maximal flow rate of complex atherosclerotic disease and anatomic varia-
is exceeded, the pressure in the system increases. Most tions of the arch are clearly delineated before navigating a
power injectors are set to abort injection when a prede- catheter into the target vessel.
termined pressure is exceeded. If the predetermined safe
acceptable injection flow rate is exceeded, most diagnostic Image angulation that may assist in defining ostial dis-
catheters will rupture (at 1,050-1,200 pounds per square ease includes LAO for the great vessels, aortic arch, and
inch). Fortunately, the injector tubing or connecters fre- renal arteries (for most patients); lateral view to steep
quently yield before the catheter does, but it is the opera- right anterior oblique (RAO) for mesenteric vessels; con-
tor’s responsibility to make sure catheter tolerances are tralateral oblique for the internal iliac ostium; and ipsi-
never exceeded. lateral oblique for the common femoral bifurcation. It is
the responsibility of the angiographer to understand the
• Maximal flow tolerance of a catheter is determined by potential satellite non-vascular issues when interpreting
catheter I.D., length, presence or absence of distal taper the results of non-selective angiography. Disease entities
or side holes, and viscosity of material being injected such as renal cell carcinoma on nephrography, or the sil-
houette of an abdominal aneurysm with mural thrombus
• An end-hole catheter should not be used for non-selec- in the abdominal aorta, must not be missed.
tive power injection
Basic Knowledge for Non-Selective Angiography
Abdominal Angiography
• Meticulous catheter flushing is important before any
Static abdominal angiography is typically used to evalu- forward injection of saline or contrast
ate the abdominal aorta and visceral branches. If the di-
agnostic objective is to exclude aorto-ostial renal artery • The pigtail catheter must be freely moving within the
stenosis, a slight left anterior oblique (LAO) view can aorta before any power injection to avoid inadvertent
provide the best definition of both renal ostia. Many ad- injection into a small side branch and to minimize the
vocate using a tennis racket or universal catheter to allow risk of atheroembolization
preferential filling of the renal arteries, decrease dilution,
and decrease the overlying artifact that is frequently seen

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CHAPTER 21 Catheters and Diagnostic Angiography

• The pressure tolerance and volume injection thresholds – Fourth, polymer-based hydrophilic catheters markedly
of each catheter should never be exceeded during a improve tracking and can be essential for access of a con-
power injection tralateral limb in a patient with a steep aortoiliac bifurca-
tion or distal aortoiliac tortuosity.
• Image angulation that may assist in defining ostial dis-
ease in non-selective angiography: In regions of the vascular tree with substantial vessel
• Great vessels/aortic arch: LAO overlap or eclipsed by a metal prosthesis, a clear under-
• Renal arteries: LAO for most patients standing of the anatomy in a 3-dimensional plane is impor-
• Mesenteric vessels: lateral view to steep RAO tant to profile the vessels correctly and to obtain definitive
• Internal iliac ostium: contralateral oblique diagnostic information. The anatomy can vary significant-
• Common femoral bifurcation: ipsilateral oblique ly from patient to patient, so there is no definitive menu
of views. Suggested views for specific vessel families are
• The angiographer must understand the potential satel- noted throughout this chapter with the caveat that indi-
lite non-vascular issues when interpreting the results of vidual anatomic variation can be considerable.
non-selective angiography

Selective Angiography Carotid and Vertebral Angiography

For the purpose of this discussion, selective angiography In the absence of azotemia, carotid and vertebral angio-
is defined as the direct injection of contrast material in a graphy should be preceded by aortic arch angiography.
preformed catheter positioned under fluoroscopic guid- The selective catheter of choice for carotid angiography
ance into a target vessel. Several principles are fundamen- depends on the characteristics of the aortic arch. Various
tal to selective angiography. pre-shaped catheters are available for carotid angiogra-
– First, a selective catheter should never be advanced for- phy and, for the purpose of discussion, these are sepa-
ward without being led by a guidewire. rated into three categories: passive (Fig. 21.2), intermedi-
– Second, hemodynamic assessment at the tip of the cath- ate (Fig. 21.3), and active (Fig. 21.4). Treatment of patients
eter should be performed before any forward injection with complex aortic arch anatomy can be challenging, and
of contrast or saline to avoid inadvertent injection of clot they are more likely to require the use of active catheters.
from the catheter tip, barotrauma to the vessel wall, athe- For example, elderly patients with long-standing hyper-
roembolism, or vessel dissection. tension can have a so-called “unwound” aorta (type III
– Third, gentle movement of the catheter is important to arch), which can be difficult to access with a simple angled
allow torque to be transmitted to the distal tip. Torque re- catheter. Also, patients with the normal anatomic variant
sponse is determined by catheter polymer characteristics of the left carotid artery originating from the innominate
and the presence or absence of a braid. artery (“bovine arch”), which occurs in 7% of patients, may
require more active diagnostic catheters. The origin of the

Fig. 21.2 Examples of passive catheters. A,
Passive carotid access (headhunter) catheters.
The headhunter catheters (H1, H3, H1H)
naturally reflect into the great vessels and
are used as workhorse systems for access
in patients with a type I arch and without
bovine right carotid anatomy. B, Passive
(multipurpose, vertebral) catheters. The
Bernstein catheter (BERN, BER 2) is similar
to the vertebral (VER); both catheters have
shorter tips than the multipurpose (MPA,
MPA1, MPR). The Bernstein hydrophilic
catheter and the glidewire are a good
combination for simple arch access.

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Vascular Medicine and Endovascular Interventions

Fig. 21.3 Examples of intermediate
catheters include the Bentson (JB 1, JB 2, JB
3; Cordis Corp, Miami Lakes, Florida), Mani
(MAN; Cordis Corp), and CK1 catheters, as
well as the Vitek (Cook Inc, Bloomington,
Indiana; not pictured). They require less
manipulation in the aorta than the “active”
catheters (see Fig. 21.4) and can be used for
access in type II and III arches.

Fig. 21.4 Examples of active catheters
include the sidewinder and Newton (Merit
Medical, South Jordan, Utah) curves. These
catheters are more active and may require
maneuvers to get into the preformed shape.
Of the several models of the Simmons
sidewinder (SIM 1, SIM 2, SIM 3, SIM 4), the
SIM 2 may be needed for complex type III
arch cases and is shaped in the left subclavian
artery. The Newton (HN 3, HN 4) is much easier
to shape in the aorta and can facilitate access
in type II or III arches.

left vertebral artery from the aortic arch is less common important to use meticulous fluoroscopic guidance. Al-
(0.5%) but is also considered a normal anatomic variant. ways lead with a wire and follow with the hemodynamic
principles of checking for damping of pressure before any
The Simmons sidewinder is considered an “active cath- injection.
eter” because it must be shaped in the ascending aorta;
this process can be a source of atheroemboli or embolic The type of diagnostic catheter used for carotid angiog-
complication. The best-accepted technique for shaping the raphy is a matter of operator preference. Most cases can be
Simmons sidewinder catheter is performed in the LAO done with an angled glide catheter or another “passive”
view. The catheter is advanced over a wire into the aortic glide system. Views that are suggested for evaluating the
arch. The wire is removed and the catheter is flushed. The extracranial carotid artery and great vessels include ipsi-
catheter is retracted and the tip positioned so the left sub- lateral oblique or true lateral for the internal carotid artery
clavian artery can be imaged. A wire is then advanced into and external carotid artery ostium; LAO for the origins of
the left subclavian artery using fluoroscopic guidance. the left common carotid, left subclavian, and innominate
The sidewinder catheter is advanced over the wire until arteries; and RAO for the origins of the right common ca-
the secondary curve is approaching the subclavian origin. rotid, right and left vertebral, left internal mammary, and
The wire is then retracted into the secondary curve and the right subclavian arteries.
catheter is advanced and rotated, allowing it to prolapse
into the ascending aorta until the tip is freely moving. The Suggested Views for Extracranial Carotid Arteries
catheter can then be rotated into the great vessel of interest and Great Vessels
and retracted into the target carotid or vertebral artery.
• Internal carotid artery: ipsilateral oblique or true lat-
With any catheter manipulation, particularly in the eral
region of the extracranial cerebrovascular system, it is

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CHAPTER 21 Catheters and Diagnostic Angiography

• External carotid artery ostium: ipsilateral oblique or Visceral Angiography
true lateral
Multiple catheter shape options are available for imag-
• Origin of left common carotid artery: LAO ing the visceral vessels, as detailed in Fig. 21.5. The celiac
• Origin of right common carotid artery: RAO and superior mesenteric arteries are most easily engaged
• Origin of right vertebral artery: RAO in the lateral view, but selective angiography typically
• Origin of left vertebral artery: RAO also requires an AP imaging profile to view branch ves-
• Origin of left internal mammary artery: RAO sels. Administration of glucagon (0.5-1 unit) 1 minute
• Origin of left subclavian artery: LAO before superior mesenteric angiography decreases the
• Origin of innominate artery: LAO bowel gas artifact and improves image quality. Contin-
• Origin of right subclavian artery: RAO ued imaging through the levophase during mesenteric
angiography with a long slow contrast injection is im-
Upper Extremity Angiography portant for definition of the mesenteric venous system
if mesenteric vein thrombosis is a consideration. The
Navigation of a selective catheter into the left upper ex- distal superior mesenteric artery distribution should be
tremity is performed in the LAO projection and then shift- examined for microaneurysms or angiographic stigmata
ed to the anterior-posterior (AP) projection as the catheter of vasculitis.
is advanced over a wire. If selecting the right subclavian
artery, it is sometimes helpful to use the RAO view to de- Renal Angiography
fine the subclavian origin while the catheter is advanced
into the right upper extremity. A popular myth is that the right renal artery projects pos-
teriorly and thus is best seen in the RAO view. Typically,
The upper extremity vessels distal to the axillary arter- however, the right renal artery arises slightly anteriorly
ies are more sensitive to catheter manipulation and spasm. and is best seen in the AP to LAO projection. It is impor-
Vasodilator therapy should be administered before power tant during selective renal angiography to meticulously
injection in the distal upper extremity in a patient with evaluate the renal parenchyma to exclude non-vascular
pronounced pericatheter spasm. Papaverine (30-60 mg) pathology, including, but not limited to, hydronephro-
is used to release spasm in the digital arteries in patients sis and renal cell carcinoma. If fibromuscular dysplasia
with vasoreactive conditions. is suspected, multiple oblique views may be required to
further define the anatomy. Quantitative measurement
In patients with suspected thoracic outlet syndrome, sta- of any renal artery aneurysm and presence or absence of
tioning the catheter in the axillary artery and monitoring concentric calcium deposition is important in defining
pressure during abduction and provocative maneuvers the natural history of fibromuscular dysplasia and must
may be beneficial. If a significant gradient is generated be part of the strategy for defining the needed views of
during provocative maneuvers, the catheter is retracted obliquity.
proximal to the subclavian axillary transition, and angio-
graphic confirmation of vessel encroachment during these
maneuvers confirms the diagnosis.

Fig. 21.5 Visceral catheter shapes. The
shepherd hook (SHK 0.8, SHK 1.0), renal
double curve (RDC, RDC1), cobra (C1,
C2, C3; based on length of the secondary
curve), RC 1, RC 2, RIM, and universal
(USL2) catheters can be used for visceral
angiography and contralateral access. The
Judkins right coronary catheter (JR4, not
shown) is also used for imaging of renal
arteries.

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Vascular Medicine and Endovascular Interventions

Contralateral Lower Extremity Access c. 0.78 in
d. All of the above
Most contralateral leg access can be simply achieved by
wire access via a pigtail, internal mammary artery, RIM, J- 3. To shape a Simmons sidewinder catheter for selective
cath, Omni-sos, or other universal flush catheter. Baseline imaging of the great vessels in a patient with a type III
angiography of the aortic bifurcation is performed, and aortic arch, what should the operator do?
the catheter is retracted into the distal aorta so the tip is a. Gently advance the catheter into the aortic arch with
facing the contralateral iliac artery. The best view to define the tip in the left coronary cusp until the preformed
the aorta is typically AP, but occasionally an oblique view shape is assumed within the arch proper.
is needed because the aorta can be rotated, particularly in b. Place the tip of the catheter in the left carotid artery
elderly women. The wire is then advanced into the con- and, after test injections of contrast, advance the cath-
tralateral external iliac artery and the catheter advanced eter into the left common carotid artery until it as-
over the wire into the target second- or third-order station sumes its preformed shaped in the ascending aorta.
for angiography. c. Advance the catheter into the aortic arch and, after
meticulous flushing, navigate a hydrophobic wire or
Access to the contralateral lower extremity is particu- other soft-tip wire into the left subclavian artery over
larly challenging in patients with a high aortoiliac bifurca- which the catheter is advanced until the secondary
tion, abdominal ectasia or aneurysmal change, previous curve addresses the subclavian ostium. At this point,
aortobifemoral surgery, or distal native aortic tortuosity. the wire is retracted into the secondary curve and the
In these cases, it may be best to start with a more support- catheter advanced and rotated until it forms its pre-
ive catheter like the Omni-sos or universal. The catheter formed shape in the ascending aorta.
is retracted into the bifurcation over a regular hydrophilic d. Move the catheter into the thoracic aorta until the
angled wire (glidewire). The hydrophilic wire tip is then tip engages a thoracic branch, then advance until the
turned to address the lateral iliac wall and advanced into catheter assumes its preformed shape. Advance the
the contralateral external iliac artery. Often the wire must catheter over the arch and then retract it into the tar-
be advanced deep into the contralateral superficial femo- geted great vessel.
ral or profunda femoris artery to provide “anchor” sup- e. All of the above can be used.
port to advance the universal flush catheter forward. If
the universal flush catheter will not advance, an angled 4. During non-selective abdominal angiography, the
braided hydrophilic catheter (glide catheter) can be used, power injector suddenly stops injection when the preset
and this combination allows access to the contralateral pressure threshold of 900 pounds per square inch (psi)
limb in most cases. Occasionally, a Simmons sidewinder is exceeded. What should the operator do?
or more aggressive curve is needed, but this should be a. Increase the threshold to 1,200 psi and proceed with
considered only in unusual cases in which brachial access injection
or ipsilateral approach is not advised. b. Withdraw blood from the catheter and flush
c. Make certain the flush catheter is moving freely with-
Questions in the aorta
d. Evaluate all connections and tubing for kinks or ob-
1. A 64-year-old, right-handed carpenter presents with struction
right arm claudication and becomes dizzy when using e. b, c, and d
a hammer. He has a normal right carotid pulse and de-
creased right arm blood pressure compared with the 5. During carotid angiography with an end-hole hy-
left. Duplex ultrasonography shows right vertebral drophilic catheter, attempts to withdraw blood and
flow reversal. What is most likely to be the best view to flush the catheter are unsuccessful because of suspected
image the lesion? occlusion of the catheter or kink in the catheter. What
a. Left anterior oblique should the operator do?
b. Straight AP a. Remove the catheter over a wire
c. Right anterior oblique b. Remove the catheter and flush outside the body
d. True lateral c. Proceed with power injection
e. AP cranial d. Inject a small amount of heparinized saline forward
to clear the catheter
2. What is the O.D. of a 6F diagnostic catheter?
a. 6 CH 6. A patient enters the hospital with a suspected congeni-
b. 1.98 mm tal arteriovenous malformation between the renal ar-

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CHAPTER 21 Catheters and Diagnostic Angiography

tery and renal vein. For non-selective angiography of a. Is a normal anatomic variant
the abdominal aorta, the need is anticipated for a high b. Occurs in as many as 7% of patients
volume of contrast material. A 6F, 0.035-in wire–com- c. May require the utilization of a more “active” cath-
patible, 100-cm length pigtail catheter is selected. Dur-
ing attempts to inject 60 mL of contrast over 2 seconds, eter like the Simmons sidewinder, Vitek, or Newton
the power injector tubing splits and contrast is sprayed catheter for selective angiography
throughout the room. How may this situation have been d. All of the above
avoided?
a. Utilization of a 65-cm pigtail catheter from the same 9. A patient enters the hospital with severe right foot pain
and absent right pedal pulses. The patient has docu-
family mented severe osteoarthritis that required bilateral hip
b. A better understanding by the operator regarding the and knee replacements. Traditional angiography with
bilateral lower extremity runoff shows luminal irregu-
maximal flow rate for the catheter selected larity and calcification but no focal area of significant
c. The appropriate setting of a pressure limit on the stenosis. What would be the next best diagnostic test?
a. Erythrocyte sedimentation rate and additional sero-
power injector below the threshold for the injector logic testing for vasculitis
tubing or catheter selected b. Cardiac work-up for possible embolic source
d. Use of a high-flow pigtail catheter that is 100 cm in c. Steep oblique image intensifier angulation or cross
length but has a larger internal diameter table views of the ipsilateral popliteal and tibiopero-
e. Dilution of the contrast material neal system before moving the patient off the table
f. All of the above d. Venous studies of the right lower extremity

7. During abdominal angiography, the patient has severe Suggested Readings
back pain followed by hypotension and loss of motor
and sensory function below the waist. This complica- Baum S, Pentecost MJ, editors. Abrams’ angiography: interven-
tion: tional radiology. 2nd ed. Philadelphia: Lippincott Williams &
a. Could have been avoided by stationing the catheter Wilkins; 2006.
below T12.
b. Could have been avoided by making certain that the Osborn AG. Diagnostic cerebral angiography. 2nd ed. Philadel-
catheter was free moving in the aorta before injec- phia: Lippincott Williams & Wilkins; 1999.
tion.
c. May be improved by venting of the spinal fluid, but Singh H, Cardella JF, Cole PE, et al, Society of Interventional Ra-
this is based on anecdotal experience. diology Standards of Practice Committee. Quality improve-
d. Is likely to result in long-term paralysis. ment guidelines for diagnostic arteriography. J Vasc Interv
e. All of the above. Radiol. 2003;14:S283-8.

8. Baseline aortic arch angiography in a patient before Spies JB, Bakal CW, Burke DR, et al, Standards of Practice Com-
selective left carotid angiography shows that the left mittee of the Society of Cardiovascular and Interventional Ra-
carotid artery originates from the brachiocephalic trunk diology. Standards for interventional radiology. J Vasc Interv
approximately 1 cm distal to the brachiocephalic os- Radiol. 1991;2:59-65.
tium. This finding:
Uflacker R, editor. Atlas of vascular anatomy: an angiographic
approach. Baltimore: Williams & Wilkins; 1997.

233

22 Endovascular Techniques II: Wires,
Balloons, and Stents

Ian R. McPhail, MD

Wires Small-diameter wires, as used in the coronary arteries,
have become increasingly popular for peripheral access
Angiography wires come in all shapes, sizes, intricacies, and interventions. For example, the micropuncture set
and capabilities. Variables include diameter, length, tip uses a small needle with a 0.018-in wire to obtain access.
shape, visibility, hydrophilic coating, tip and shaft stiff- The dilator system is introduced and the 3F/0.018-in inner
ness, docking, and torque properties. Major classification dilator is removed from within the 4F/0.035-in outer dila-
is often by size, grouping 0.035/0.038-in and 0.014/0.018- tor, allowing for the insertion of a standard 0.035-in ac-
in diameter wires. Access wires for the femoral approach cess wire. This is an extremely useful system for entering
and for diagnostic angiography of large and medium-sized arm vessels and the internal jugular vein, especially under
vessels are usually 0.035 inches in diameter, with J-shaped ultrasonographic guidance. The sharp, fine needle is also
or soft floppy tips that are unlikely to inadvertently enter good for cutting through scar tissue and for entering the
an unwanted branch vessel or initiate a dissection during small femoral arteries of some young women and children.
access or catheter exchange. Their usual construction is a Catheter exchanges, positioning, and primary branch ac-
core wire with an outer spiral wrap, allowing the tip to be cess are usually performed with 0.035-in wires. However,
straightened for insertion by applying tension to the wrap 0.014/0.018-in systems are superb tools for intervention
over the core with one hand. on smaller vessels and have been adopted by most opera-
tors. The 0.014-in wires dominate coronary work. These
These wires have little directional control and rely on wires generally have a shapeable tip that is visible under
large, open vessels for passage or shaped catheter ma- fluoroscopy. They are less traumatic than thicker wires
nipulation for steering. They have soft to medium shaft and are conveniently paired with low-profile balloons and
stiffness and are often used as the working wire for in- stents that easily cross tight lesions. A hydrophilic coating
terventions on larger vessels. Wires with similar tips but may be applied to all or just the tip of the wire. Tip length
much stiffer shafts (such as 0.035-in wires) are useful in and shaft properties vary. Rapid exchange balloons (de-
obtaining access through heavily scarred groins in which scribed below) and stents are commonly paired with these
a dilator might kink a standard wire, for straightening tor- smaller wires.
tuous iliac segments and endografting the aorta, and for
work in the great vessels. Shaped or shapeable tips, on a Several specific recommendations can be made for
shaft responsive to torque (especially with a hydrophilic using wires. 1) Choose the wire diameter, length, tip con-
coating), are invaluable in accessing branch vessels and figuration, coating, and handling properties specifically
crossing stenoses. Hydrophilic wires are essential in tortu- for the task at hand. 2) If the wire does not advance eas-
ous vessels, recanalization work, and crossing the aortic ily, do not just force it. 3) Do not use a hydrophilic-coated
bifurcation from a contralateral approach. However, hy- wire through a needle; the coating might shear off. 4) If a
drophilic wires are more difficult to handle (slippery when wire with a spiral wrap gets caught on something (e.g., the
wet and sticky when dry), potentially more traumatic, and apex of an inferior vena cava filter or the tip of a needle),
should not be used as routine access or working wires. do not pull on it or the wrap will unravel. Instead, ad-
vance the wire, preferably with catheter support. 5) Either
© 2007 Society for Vascular Medicine and Biology the soft or stiff end of a wire can be partially advanced
through a catheter to change the shape of the distal end of
the catheter (e.g., open it up). 6) Choose hydrophilic wires

234

CHAPTER 22 Wires, Balloons, and Stents

(vs non-hydrophilic “working wires”) for tortuous vessels Aside from being able to position a balloon of the de-
and for crossing difficult lesions. sired size across the lesion and inflate it to adequate pres-
sure, the most important property in practice is the issue
Wire Do’s and Don’ts of balloon compliance. Compliance refers to the relation-
ship between changes in volume and pressure. A compli-
• Do select the correct wire (diameter, length, tip, stiff- ant balloon increases in diameter as pressure increases. A
ness, torque control, visibility) for the job non-compliant balloon reaches its predetermined nominal
maximum diameter and enlarges very little as inflation
• If the wire doesn’t go in easily, don’t just push pressure increases. This property of non-compliant bal-
• Don’t use a hydrophilic-coated wire through a needle; loons concentrates force on the resistant part of a stenosis
without assuming a “dog bone” configuration and over-
the coating might shear off dilating the adjacent vessel. Balloon compliance is also im-
• If a wire with a spiral wrap gets caught on something, portant when expanding a stent. A compliant balloon will
continue to expand beyond its stated diameter as pressure
don’t pull or the wrap will unravel. Instead, advance is increased, which allows the operator to size the balloon
the wire, preferably with catheter support conservatively (i.e., undersize slightly for safety) and then
• Either the soft or stiff end of a wire can be partially ad- expand the balloon further, if desired, by increasing the
vanced through a catheter to change the shape of the pressure.
distal end of the catheter
• Choose hydrophilic wires for tortuosity and crossing Balloons may be mounted on shafts to accept either
difficult lesions vs non-hydrophilic “working wires” smaller (0.014/0.018-in) or larger (0.035/0.038-in) wire di-
ameters—generally for use in smaller and larger vessels,
Balloons respectively. Imaging through the sheath or guide catheter
with the balloon in situ is easier with the smaller systems,
This discussion will focus on high-pressure, non-elastic and they can cross very tight lesions through tortuous ac-
angioplasty balloons (as opposed to low-pressure, elas- cess.
tomeric balloons used for vessel occlusion, embolectomy,
or fixation). Current angioplasty balloons are available in The balloon may be mounted on a shaft that takes the
many diameters and lengths. Made with a thin wall of ma- wire through the full length of the shaft (“over-the-wire”
terials such as polyethylene terephthalate or nylon, they systems) or one that takes the wire only through its distal
tend to maintain their shape and size under high infla- end, with the wire exiting out the side of the shaft a short
tion pressure (typically 8-20 atm and sometimes as high as distance back from the balloon (“rapid exchange”). The
30 atm). Of these 2 materials, polyethylene terephthalate advantages of an over-the-wire system are that wire ex-
is stronger and the balloon can have a thinner wall and change can be performed with the balloon in situ and that
lower profile; nylon is weaker but softer and deflates more contrast material can be injected through the shaft lumen
easily, facilitating removal. Of note, inflating a balloon where the wire passes. However, a long wire is required,
with undiluted high-viscosity contrast fluid may make it which can be cumbersome. Rapid exchange systems use
difficult to deflate and remove. a shorter wire and facilitate faster balloon placement and
exchange, usually with less wire movement.
Per Laplace’s law, wall stress increases with balloon ra-
dius for a given pressure. Therefore, larger balloons tend Cryoplasty balloons produce a cold thermal injury to
to have lower burst pressures; this can be overcome with the vessel by inflating with liquid nitrous oxide that turns
various reinforcing materials. The following equation de- to gas. These balloons have recently received consider-
fines the stress on a typical angioplasty balloon: able attention in the media, but their superiority remains
unproven. Cutting balloons have blades that are brought
Radial (hoop) stress = (pressure × radius)/(2 × thickness) into contact with the vessel wall during inflation and are
useful in resistant lesions.
Because radial stress is greater than longitudinal, balloons
usually tear along their long axis rather than circumferen- Balloon Do’s and Don’ts
tially. A longitudinal tear may be less likely to catch on a
lesion or stent than a circumferential tear and less likely to • Do not use undiluted high-viscosity contrast material in
perforate a vessel than would a high-pressure jet from a a balloon or it may be difficult to deflate
pinhole-type balloon rupture.
• Choose balloon length carefully. One that is too long can
Balloon length should be based on the length and shape traumatize adjacent “normal” endothelium; this also
of the target lesion. One that is too long can traumatize applies to the “shoulders” of the balloon. A balloon that
adjacent “normal” endothelium; this also applies to the is too short may “squirt” out of position during infla-
“shoulders” of the balloon. A balloon that is too short may tion
“squirt” out of position during inflation.

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Vascular Medicine and Endovascular Interventions

• If the balloon bursts before successful dilation, a larger pendent variables determine stent design, including size,
balloon is even more likely to burst (due to Laplace’s configuration, and material composition. Longitudinally
law) oriented struts seem favorable for patency, but transverse
elements are needed for flexibility. Lower profile (thinner
• Laplace’s law for a cylinder: Tension = Pressure × Ra- in the radial direction) struts also seem to be associated
dius with less restenosis and allow a smaller delivery system.
Large interstices (i.e., a low mesh density) mean that
• Compliant balloons enlarge with increasing pressure; smaller struts are indenting the vessel wall and providing
non-compliant balloons concentrate force on the steno- less surface coverage. The small struts put higher local
sis rather than assuming a “dog bone” shape pressure on the wall and incite more intimal hyperplasia.
Thus, radial strength, wall coverage, and delivery system
• Over-the-wire balloons allow wire exchange and distal size are some of the competing elements in stent design.
contrast injection through the balloon catheter shaft;
rapid exchange balloons facilitate shorter wires Other interconnected variables include foreshorten-
ing, expandability, and flexibility. The less a stent fore-
Stents shortens when it is deployed, the easier it is to achieve
precise placement. Expandability allows for a smaller
Vascular stents are metal frameworks that support the size in the collapsed state and some play in the final
lumen from within. Much of what is known about stents diameter. Although balloon-expandable stents are not
has been learned in the coronary circulation. In 1994, the nearly as flexible as self-expanding stents, some degree
results of 2 clinical trials, from the Benestent Study and of flexion is still required of balloon-expandable stents
Stent Restenosis Study (STRESS), established stents as su- to facilitate passage through tortuous access vessels. The
perior to balloon angioplasty alone in preventing resteno- alloys used vary in strength, vessel response, and visibil-
sis in the coronary circulation. The US Food and Drug Ad- ity under fluoroscopy. Earlier stents were stainless steel,
ministration (FDA) approved the first balloon-expandable with newer designs favoring cobalt-chromium alloys. The
coronary stent that same year, and use of this type of stent most biocompatible material has yet to be determined.
has skyrocketed since, including broad application in the Magnesium-based and other absorbable stents are under
peripheral vasculature. Stents work well to prevent acute investigation.
recoil after angioplasty, maximize lumen diameter, and
“tack down” dissection flaps. However, although stents Self-Expanding Stents
support the lumen, they also increase the risk of subacute
thrombosis and incite intimal hyperplasia. The throm- As the name implies, self-expanding stents are released
bosis problem can be largely overcome with antiplatelet from their constraining delivery mechanism and expand
therapy and high-pressure balloon inflation. within the vessel until the stent reaches its predetermined
maximum diameter or is constrained by the vessel wall.
Drug-eluting stents and newer stent designs have lower Basic configurations include spiral and mesh. They are
restenosis rates. However, neither the use of clopidogrel much more flexible than balloon-expandable stents and
nor the use of drug-eluting stents has been proven effective will recoil if a compressive force is applied. They are also
in the peripheral circulation. Furthermore, surprisingly available in larger sizes. These properties are invaluable
few good, prospective, randomized trials have published in applications such as use in the superficial femoral and
data supporting the benefit of stents in the periphery; carotid territories where the vessels are subject to bending
these stents are often used “off label” (e.g., bronchial- or or movement.
biliary-approved stents used in the vasculature) in clinical
practice. Current stents may be broadly classified as bal- The archetypal self-expanding stent is the Wallstent. It
loon-expandable or self-expanding. is well known to most practitioners. The stent is made of
a low-iron-content (safe for use with magnetic resonance
Balloon-Expandable Stents imaging [MRI]) biomedical superalloy braided into a
mesh cylinder. It is elongated when constrained in the de-
Balloon-expandable stents rely on inflation of an angio- livery system and shortens considerably as it is deployed
plasty balloon to expand the stent from its collapsed con- distally to proximally, back along the delivery catheter.
figuration and push it into contact with the vessel wall. Therefore, the tip can be accurately positioned during the
Most contemporary stents are factory-mounted on the bal- initial phase of deployment, but it is very difficult to know
loon. They have become much easier to use since the early where the back end of the stent will end up. It is flexible
days of the stiff but strong unmounted Palmaz-Schatz and not prone to kinking, but difficulties with accurate
stent. Computer-guided laser cutting of alloy tubes has placement have led to more widespread use of nitinol self-
facilitated the manufacture of complex new stent designs expanding stents.
with vastly improved handling properties. Many interde-

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CHAPTER 22 Wires, Balloons, and Stents

Nitinol (a “shape memory alloy”) derives its name from of a drug to prevent restenosis. Agents used include the
nickel-titanium/Naval Ordnance Laboratory, referring to anti-proliferative drugs sirolimus and paclitaxel. FDA
the components of the alloy and the site of its discovery in approved for coronary use since 2003, they have become
1961. Nitinol stents are appealing because they revert to popular, with substantially lower restenosis rates than bare
their original shape when warmed to body temperature. metal stents. However, they are expensive, and patients
This allows both a compact delivery system and an out- must remain on clopidogrel for 6 months after placement
ward radial force in the vessel after placement. The stents to prevent thrombosis. Early studies have been done in the
are MRI safe, flexible, and foreshorten little. Accurate place- periphery including the renal, superficial femoral artery,
ment is much easier than with the Wallstent, although they and tibial territories, with mixed results.
are difficult to see under fluoroscopy and usually have
marker dots at both ends. Despite their flexibility, nitinol Non-Invasive Imaging After Stent Placement
stents have been prone to fracture in the superficial femo-
ral artery, which is associated with decreased patency. Non-invasive imaging is complicated by stent placement.
Most contemporary stents are not ferromagnetic and are
Coil stents consist of a continuous coil of wire. Early cor- therefore MRI safe. (Web sites such as www.mrisafety.
onary versions included the GRII and the Wiktor stents, com are useful online references for various intravascular
which had poor patency. The IntraCoil is FDA approved devices. If in doubt, check with the manufacturer.) Some
for the femoropopliteal arterial segment. The main advan- stents can be imaged with MRI. Others leave a black void
tage is flexibility; this stent has been used across joint lines. on the scan, which can be misinterpreted as an occlusion.
However, limited surface area is in contact with the ves- Ultrasonography can assess flow through stents. Consid-
sel wall, which may result in higher restenosis rates. One erable artifact can be produced by stents when imaged
technical peculiarity of the IntraCoil is that it should not by computed tomography, but this seems to be less of an
be oversized. It is recommended that the stent diameter issue with newer scanners and larger vessels.
match the vessel lumen diameter, rather than oversizing
slightly as is the norm with other types of stents. An over- • Balloon-expandable stents are more rigid and precise
sized coil stent will result in a tilted coil configuration. • Self-expanding stents are more flexible and available in

Another special type of self-expanding stent is the Gian- larger sizes
turco Z. Approved for use in the airways, it comes in large • Flexible stents should be used in vessels prone to move-
diameters and is useful for vascular applications such
as the vena cava. Very large interstices allow placement ment
across large branches while preserving patency. • Covered stents are generally used for aneurysms and

Other Types of Stents perforations (iatrogenic or traumatic)

Covered Stents Questions

“Covered stents” and “stent grafts” are terms loosely used 1. All of the following are advantages of self-expanding
to describe metal stents that are either covered or lined stents over balloon-expandable stents except:
with fabric (usually polytetrafluoroethylene). Examples a. Greater flexibility
include the lined Viabahn, which is FDA approved for b. Longer available stent lengths
the superficial femoral artery, and the covered Wallgraft, c. Superior overall long-term patency
which is approved for tracheobronchial use. The addi- d. Recoil in response to external compression
tion of fabric means a larger delivery system is involved.
Benefits include the ability to treat aneurysms and perfo- 2. The compliant balloon you are using breaks when at-
rations while maintaining lumen patency. Superior pat- tempting to treat a tight non-calcified lesion. The bal-
ency over traditional stents in atheromatous disease has loon size seems slightly oversized compared with the
not been proven, and covered stents may fail by abrupt adjacent vessel diameter, but the central portion of the
thrombosis. lesion never expanded beyond 50% before the balloon
broke. Your next step should be:
Drug-Eluting Stents a. A larger non-compliant balloon
b. A balloon-expandable stent
The most recent and dramatic advance in stent design is c. A self-expanding stent
the drug-eluting stent. These stents provide local release d. A non-compliant balloon of the same size

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Vascular Medicine and Endovascular Interventions

3. All of the following are true of balloon-expandable a. Deflate the balloon after 10 minutes to see if the bleed-
stents except: ing stops, and perform no further intervention if the
a. Precise placement is easier than with self-expanding bleeding has stopped
stents
b. Gold coatings favor patency b. Refer for emergent open surgical repair
c. Horizontal struts favor flexibility c. Prepare to place a covered stent
d. They are less flexible than self-expanding stents d. Coil embolize the external iliac artery with plans for

4. A flow-limiting dissection results after you dilate an ex- subsequent femoral-femoral crossover bypass graft
ternal iliac artery stenosis from a contralateral approach
through a sheath over the aortic bifurcation. Your first Suggested Readings
choice should be:
a. Puncture the affected side and place a self-expanding Fischman DL, Leon MB, Baim DS, et al, Stent Restenosis Study
stent Investigators. A randomized comparison of coronary-stent
b. Place a self-expanding stent through the indwelling placement and balloon angioplasty in the treatment of coro-
sheath nary artery disease. N Engl J Med. 1994;331:496-501.
c. Place a balloon-expandable stent through the in-
dwelling sheath Palmaz JC. Intravascular stents in the last and the next 10 years.
d. Puncture the affected side and place a balloon-ex- J Endovasc Ther. 2004;11 Suppl 2:II200-6.
pandable stent
Palmaz JC, Bailey S, Marton D, et al. Influence of stent design
5. An external iliac artery angioplasty is complicated by and material composition on procedure outcome. J Vasc Surg.
vessel rupture with brisk bleeding and a sudden de- 2002;36:1031-9.
crease in blood pressure. After reinflating the balloon to
control bleeding, your next step should be: Serruys PW, de Jaegere P, Kiemeneij F, et al, Benestent Study
Group. A comparison of balloon-expandable-stent implanta-
tion with balloon angioplasty in patients with coronary artery
disease. N Engl J Med. 1994;331:489-95.

Serruys PW, Kutryk MJ, Ong AT. Coronary-artery stents. N Engl
J Med. 2006;354:483-95.

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23 Aortoiliac Intervention

Christopher J. White, MD

Introduction lary approach) or via a femoral (ipsilateral or contralateral)
artery. Using a standard Seldinger technique, arterial ac-
Patients with aortoiliac occlusive disease may present cess is obtained, and a 4F to 6F vascular sheath is inserted.
with a full range of symptoms, from mild claudication to Heparin administration is optional. A pigtail catheter or
limb-threatening ischemia. The severity of symptoms is other angiographic catheter is advanced to the level of the
multifactorial and depends on the severity of the occlu- renal arteries over a guidewire. Diagnostic aortography
sive lesion, the presence of collateral vessels, and the pres- is used to demonstrate inflow and outflow of the target
ence of multilevel vascular disease. In the case of isolated lesion, and runoff angiography is performed to visualize
terminal aorta stenoses, both legs generally are equally the lower extremity circulation. A “working view” of the
affected, although disparities in collateral circulation may lesion is obtained to serve as a “road map.” Bony land-
render one limb more ischemic than the other. marks or an external radiopaque ruler is helpful to guide
intervention. When performing diagnostic aortography, it
The initial assessment of a patient with suspected aor- is important to image the renal arteries and any collateral
toiliac occlusive disease should include a physical exami- circulation in the pelvis. Occasionally, it is necessary to
nation for signs of peripheral ischemia, distal emboliza- obtain additional selective or angulated views of the ter-
tion, and the status of the peripheral pulses. Both rest and minal aorta and common iliac arteries to define the extent
exercise ankle-brachial index (ABI) should be measured. of the stenosis.
A mild impairment in the resting ABI may be markedly
exaggerated with exercise. Segmental ABIs with pulse- Abdominal Aorta Intervention
volume recordings can indicate the presence or absence
of multilevel occlusive disease. Another helpful test in the Distal abdominal aortic disease conventionally has been
preprocedural assessment of these patients is the duplex treated with endarterectomy or bypass grafting. Fre-
examination (Doppler and ultrasonography). The duplex quently, distal aortic occlusive disease accompanies oc-
scan provides information regarding the presence or ab- clusive disease of the common or external iliac arteries.
sence of abdominal aortic aneurysmal disease and indi- The potential advantages of a percutaneous technique
cates the severity of occlusive lesions. If the presence of compared with aortoiliac reconstruction are substantial
aneurysmal disease is not certain, abdominal computed in that general anesthesia and abdominal incision are not
tomography or magnetic resonance imaging may be per- required, and percutaneous therapy is associated with
formed. a shorter hospital stay and lower morbidity. Although
axillofemoral extra-anatomic bypass offers a lower-risk
Aortoiliac Angiography surgical alternative for patients with terminal aorta oc-
clusive disease and severe comorbid conditions, it has
Vascular access for aortoiliac angiography may be ob- the disadvantages of a lower patency rate than direct
tained from the upper extremity (radial, brachial, or axil- surgical bypass of the lesions and requires that surgical
intervention of a normal vessel be performed to achieve
© 2007 Society for Vascular Medicine and Biology inflow.

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Vascular Medicine and Endovascular Interventions

• Axillofemoral extra-anatomic bypass is a lower-risk • Lifestyle-limiting or progressive claudication
surgical alternative for patients with terminal aorta oc- • Ischemic pain at rest
clusive disease and severe comorbid conditions • Non-healing ischemic ulcerations
• Gangrene
• Disadvantages are lower patency rate than direct sur-
gical bypass of the lesion and requirement for surgical Subsets of patients and lesions ideally suited to balloon
intervention of a normal vessel to achieve inflow angioplasty have been proposed (Table 23.1); contrain-
dications are listed in Table 23.2. Clinical success is more
Since 1980, balloon angioplasty has been used success- likely 1) with stenoses than with occlusions, 2) with aor-
fully in the terminal aorta. An extension of this strategy toiliac disease than with femoropopliteal or tibioperoneal
has been the use of endovascular stents in the treatment disease, and 3) in patients with claudication than in those
of infrarenal aortic stenoses. Although balloon dilation of requiring limb salvage (Table 23.3). The primary success
these lesions has been reported to be effective, the place- rate of angioplasty for selected iliac artery stenoses is more
ment of stents offers a more definitive treatment with a than 90%, with 5-year patency rates between 80% and 85%;
larger acute gain in luminal diameter, scaffolding of the iliac occlusions, however, have a lower procedural success
lumen to prevent embolization of debris, and enhanced rate (33%-85%). The clinical benefit of percutaneous trans-
long-term patency compared with balloon angioplasty luminal angioplasty (PTA) versus medical therapy in iliac
alone. Excellent results at late follow-up (mean, 48 months) lesions has been demonstrated in a randomized trial with
were reported in 24 patients treated with infrarenal aortic end points that included relief of symptoms, improve-
stents, with no in-stent restenosis. ment in walking distance, and continued patency of the
affected artery.
• Balloon dilation of infrarenal lesions is reportedly effec-
tive, but stent placement is a more definitive treatment Table 23.1 Ideal Iliac Artery Lesions for PTA

• Advantages of stents: Stenotic lesion
• The acute gain in luminal diameter is larger Non-calcified lesion
• Scaffolding of the lumen helps prevent embolization Discrete (≤3 cm) lesion
of debris Patent runoff vessels (≥2)
• Long-term patency is enhanced Non-diabetic patient

Stents are an attractive therapeutic option for the man- PTA, percutaneous transluminal angioplasty.
agement of large artery occlusive disease to maintain or
improve the arterial luminal patency after balloon angio- Table 23.2 Relative Contraindications for Iliac Artery PTA
plasty. The efficacy of stents versus balloon angioplasty
for aortic stenoses has not been demonstrated in ran- Occlusion
domized trials. Long lesion (≥5 cm)
Aortoiliac aneurysm
Iliac Artery Intervention Atheroembolic disease
Extensive bilateral aortoiliac disease
Iliac artery intervention is an important skill for the cardio-
vascular interventionalist to master, not only to improve PTA, percutaneous transluminal angioplasty.
blood flow to the lower extremities, but also to preserve
vascular access for what may be lifesaving cardiovascu- Table 23.3 Patency After Iliac PTA by Clinical and Lesion Variables
lar therapies such as coronary intervention, insertion of
an intra-aortic counterpulsation balloon, or treatment of Patency, %
vascular access complications. Indications for iliac inter-
vention to relieve symptomatic lower extremity ischemia Variables 1-year 3-year 5-year
include 1) lifestyle-limiting or progressive claudication, 2)
ischemic pain at rest, 3) non-healing ischemic ulcerations, ST/CL/GR 81 70 63
and 4) gangrene. A major principle of angiographic imag- ST/LS/GR 65 48 38
ing is to demonstrate the angiographic anatomy of the in- OC/CL/PR 61 43 33
flow and outflow vessels before performing intervention. OC/LS/PR 56 17 10

• Indications for iliac intervention to relieve symptomatic CL, claudication; GR, good runoff; LS, limb-threatening ischemia; OC,
lower extremity ischemia include: occlusion; PR, poor runoff; PTA, percutaneous transluminal angioplasty; ST,
stenosis.

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