Maintenance of Certification in Cardiology
The only class I indication for abdominal aortic aneurysm (AAA) screening is for men, 60 years of age or older, who are either the siblings or offspring of patients with AAAs (level B evidence). Physical examination and ultrasound screening are recommended in these patients. A class IIa indication is given for men who have a history of smoking and are between 65 and 75 years of age (level B evidence). Although men and women with coronary artery disease (CAD), lower extremity peripheral arterial disease, and long-standing diabetes mellitus may be at increased risk for AAAs, there is currently insufficient evidence to recommend routine screening in these patients.
Management of asymptomatic infrarenal AAAs measuring 4.0 to 5.4 cm in diameter involves aggressive control of blood pressure and lipids, smoking cessation (if appropriate), and serial reassessment of aneurysm size. This patient’s blood pressure is well-controlled and he has no history of hyperlipidemia. Although assessment of his lipid profile would be reasonable, no further intervention is required at this time; however, repeat abdominal ultrasonography or computed tomography (CT) scanning is indicated at 6- to 12- month intervals (class I, level A evidence). Beta-blockers have not been shown to reduce the rate of aneurysm expansion and are not recommended, except for blood pressure control (class IIb, level B evidence). In the absence of chest discomfort or other symptoms of ischemia, routine stress testing to evaluate for CAD in patients with AAA is not recommended. Although avoidance of strenuous exertion and heavy lifting seems prudent, there is no evidence that curtailment of moderate activity reduces the risk of aneurysm expansion or rupture. Intervention is not recommended for asymptomatic infrarenal AAAs measuring less than 5 cm in men or less than 4.5 cm in women (class III, level A evidence).
Timely repair of infrarenal or juxtarenal AAAs measuring 5.5 cm or larger is recommended to reduce the risk of rupture, whether or not the patient is symptomatic (class I, level B evidence). In patients who are good or average surgical candidates, such as the patient described in this vignette, open surgical repair is recommended as the treatment of choice (class I, level B evidence). Endovascular repair is a reasonable therapeutic option in patients at high surgical risk secondary to major comorbid conditions (class IIa, level B evidence), but is not recommended in patients at low or average surgical risk (class IIb, level B evidence). Although patients with AAA often have concomitant CAD, there is no evidence that routine coronary revascularization before vascular surgery improves clinical outcomes, especially in the absence of symptoms; thus, routine stress testing and coronary angiography are not recommended before AAA repair in asymptomatic patients.
The patient’s history and physical examination are consistent with intermittent claudication due to lower extremity peripheral arterial disease. Current guidelines recommend assessment of the ankle-brachial index (ABI) as the initial diagnostic test in patients with intermittent claudication, in part because of the high sensitivity and low cost associated with the procedure (class I, level B evidence). If the resting ABI is normal, the measurement should be repeated after exercise. Choices B to E may be appropriate in selected patients with symptomatic lower extremity peripheral arterial disease and an abnormal ABI, but none are indicated as the initial diagnostic procedure.
The patient’s ABI confirms the presence of moderate peripheral arterial disease involving the left lower extremity; the ABI on the right is normal (normal, 0.91-1.30). In the absence of critical limb ischemia, defined as rest pain, ulceration, or gangrene, the initial therapeutic approach is aimed at aggressive treatment of cardiovascular risk factors and relief of symptoms. Symptomatic lower extremity peripheral arterial disease is a “coronary risk equivalent.” As such, treatment
with a statin to achieve a low-density lipoprotein (LDL) cholesterol level <100 mg/dL is indicated (class I, level B evidence). Smoking cessation and optimal control of hypertension and diabetes in accordance with current guidelines are also recommended. Aspirin, 75 to 325 mg daily, is indicated to reduce the risk of myocardial infarction, stroke, and vascular death (class I, level A evidence). A supervised exercise program consisting of 30- to 45-minute sessions at least 3 times per week for at least 12 weeks has been shown to improve walking distance by 50% or more and is recommended as an initial treatment for patients with intermittent claudication (class I, level A evidence). Cilostazol, a phosphodiesterase
type III inhibitor, is the only pharmacologic agent currently approved for use in the United States for which there is convincing evidence of improvement in symptoms and walking distance. Therefore, cilostazol is recommended as a reasonable therapeutic option in patients with limiting symptoms attributable to intermittent claudication (class I, level A evidence). Cilostazol is not recommended in patients with heart failure. Pentoxifylline is also approved for the treatment of intermittent claudication, but the efficacy of this agent is not well established (class IIb, level C evidence). Referral to a vascular surgeon is not indicated, except in cases of critical limb ischemia or severe limiting symptoms that do not respond to medical therapy.
In the absence of critical limb ischemia, continued conservative management remains a reasonable therapeutic option based on symptom severity, the extent to which symptoms limit activities and impair quality of life, and patient preferences. For patients with severe symptoms that do not respond satisfactorily to intensive medical therapy and supervised exercise, revascularization with either percutaneous balloon angioplasty or an arterial bypass procedure is warranted (class I, level A evidence). Primary stent placement in the femoral, popliteal, or tibial arteries is not indicated based on data from multiple randomized trials that have failed to show improved outcomes with stenting compared with angioplasty alone (class III, level C evidence).
Factors known to increase limb loss in patients with critical limb ischemia include diabetes mellitus, cigarette smoking or use of other tobacco products, severely decreased cardiac output due to severe heart failure or shock, severe renal failure, vasospastic diseases (eg, Raynaud’s phenomenon), prolonged cold exposure, infections of the distal limb (eg, cellulitis, osteomyelitis), skin breakdown, and traumatic injury. The risk of limb loss is not affected by a patient’s sex.
Duplex ultrasonography, CT angiography, and magnetic resonance angiography (MRA) are all recommended as appropriate screening tests to establish a diagnosis of renal artery stenosis (class I, level B evidence). Contrast angiography is indicated in cases where clinical suspicion is high and the results of noninvasive tests are inconclusive (class I, level B evidence). Captopril renal scintigraphy (level C evidence), selective renal vein renin measurements (level B evidence), plasma renin activity (level B evidence), and the captopril-renin test (level B evidence) are not recommended as appropriate tests to screen for renal artery stenosis because of their low sensitivity and/or specifi city (all class III).
Renal artery stent placement is the procedure of choice for treatment of severe uncomplicated renal artery stenosis associated with resistant or refractory hypertension (class I-IIa, level B evidence). A single focal ostial lesion in a large renal artery provides the optimal conditions for successful stent placement. Following the procedure, most patients obtain significant clinical benefit in terms of blood pressure control; however, “cure” of hypertension is rare and some patients receive no demonstrable benefit from the procedure. Percutaneous angioplasty without stenting is the procedure of choice in young patients with renal artery stenosis secondary to fibromuscular dysplasia, but it is less effective than stenting in patients with atherosclerotic renal artery stenosis. Vascular surgical reconstruction and bypass grafting are effective treatments for renal artery stenosis, but because these procedures are more invasive, they are generally reserved for patients with more complex anatomy, such as early branching of the artery, multiple small arteries requiring intervention, or associated severe aortic atherosclerosis. The addition of an angiotensin receptor blocker (ARB), such as valsartan, is unlikely to improve blood pressure control in this patient, who is already taking 5 antihypertensive medications including an angiotensin-converting enzyme (ACE) inhibitor. In addition, the combination of an ACE inhibitor and an ARB has been associated with an increased risk of worsening renal function and hyperkalemia.
Acute intestinal ischemia is an uncommon but potentially life-threatening condition that most often occurs as a result of arterial embolization or in situ thrombosis. The condition affects twice as many women as men, and the median patient age at onset is 70 years. Most patients have preexisting cardiovascular disease. In the majority of cases, arteriography is the most useful diagnostic test and is preferable to either duplex ultrasonography or CT scanning. In patients with confirmed mesenteric artery obstruction and evidence of bowel ischemia, early surgical exploration is recommended, before the onset of peritoneal signs or evidence of infection, both of which increase perioperative mortality. Percutaneous interventions may be effective in revascularizing ischemic tissue, but do not obviate the need for surgery in patients with nonviable intestine. Moreover, restoration of blood flow to infarcted bowel as a result of either percutaneous or surgical revascularization may cause a sudden release of endotoxins into the circulation, leading to the adult respiratory distress syndrome, disseminated intravascular coagulation, and endotoxemic shock.
Source (questions 1-10)
Hirsch AT, Haskal ZJ, Hertzer NR, et al. ACC/AHA guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic): executive summary.
J Am Coll Cardiol