Peripheral Arterial Disease

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Chapter 55

Peripheral Arterial Disease

1. What are the key components of the vascular physical examination?

    According to the American College of Cardiology/American Heart Association (ACC/AHA) guidelines on peripheral arterial disease (PAD), the key components of the vascular physical examination include the following:

image Blood pressure measurements in both arms

image Carotid pulse palpation for upstroke and amplitude, and auscultation for bruits

image Auscultation of the abdomen and flank for bruits

image Palpation of the abdomen for aortic pulsation and its maximal diameter

image Palpation of brachial, radial, ulnar, femoral, popliteal, dorsalis pedis, and posterior tibial pulses; pulse intensity is scored as follows: 0, absent; 1, diminished; 2, normal; 3, bounding

image Performance of the Allen test when knowledge of hand perfusion is needed

image Auscultation of the femoral arteries for the presence of bruits

image Inspection of the feet for color, temperature, and integrity of the skin, and for ulcers

image Observation of other findings suggestive of severe PAD, including distal hair loss, trophic skin changes, and hypertrophic nails

2. Can the location of the patient’s lower extremity claudication help to localize the site of occlusive disease?

    The answer is a qualified yes. Because the pathophysiology of claudication is complex, there is not a perfect correlation between anatomic site of disease and location of symptoms. However, in general, the following statements can be made:

3. What noninvasive tests are used in the assessment of lower limb claudication?

image Ankle-brachial index (ABI): The ankle-brachial index is the ankle systolic pressure (as determined by Doppler) divided by the brachial systolic pressure. An abnormal index is less than 0.90. The sensitivity is approximately 90% for diagnosis of PAD. (See Question 4 for further details.)

image Pulse volume recordings (PVRs): Pulse volume recordings measure changes in volume of toes, fingers, or parts of limbs that occur with each pulse beat as blood flows into or out of the extremity. A toe-to-brachial index of less than 0.6 is abnormal, and values of less than 0.15 are seen in patients with rest pain (toe pressures of less than 20 mm Hg).

image Duplex ultrasonography: Duplex ultrasonography is a noninvasive method of evaluating arterial stenosis and blood flow. This method can localize and quantify the degree of stenosis. Ultrasonography is dependent on operator skill.

image Transcutaneous oxygen tension measurements: These measurements are useful in assessing tissue viability for wound healing. Measurements greater than 55 mm Hg are considered normal and less than 20 mm Hg are associated with nonhealing ulcers.

image Exercise testing: This testing determines treadmill walking time and preexercise and postexercise ABI. In those without significant PAD, the ABI is unchanged after exercise. In patients with PAD, the ABI falls after exercise. This test is more sensitive for detecting disease than a resting ABI alone.

4. What is the ABI?

    The ABI is the ratio of systolic blood pressure at the level of the ankle to the systolic blood pressure measured at the level of the brachial artery. More specifically, blood pressure is measured in both brachial arteries (with the higher systolic blood pressure being used) and is measured using a Doppler instrument with a blood pressure cuff on the lower calf, in both posterior tibial and dorsalis pedis arteries. Pulse wave reflections in healthy persons should result in higher blood pressures in the ankle vessel pressure (10-15 mm Hg higher than in the brachial arteries), and thus a normal ABI should be greater than 1.00. Using a diagnostic threshold of 0.90 to 0.91, several studies have found the sensitivity of the ABI to be 79% to 95% and the specificity to be 96% to 100% to detect stenosis of 50% or more reduction in lumen diameter.

    Experts emphasize that the ABI is a continuous variable below 0.90. Values of 0.41 to 0.90 are considered to be mildly to moderately diminished; values of 0.40 or less are considered to be severely decreased. An ABI of 0.40 or less is associated with an increased risk of rest pain, ischemic ulceration, or gangrene. Patients with long-standing diabetes or end-stage renal disease on dialysis and elderly patients may have noncompressible leg arterial segments caused by medial calcification, precluding assessment of the ABI. These patients are best evaluated using digital pressures and with assessment of the quality of the arterial waveform in the PVR studies. A system for interpretation of the ABI is given in Table 55-1.

TABLE 55-1

INTERPRETATION OF THE ANKLE-BRACHIAL INDEX

ABI Interpretation
>1.30 Noncompressible
1.00-1.29 Normal
0.91-0.99 Borderline (equivocal)
0.41-0.90 Mild to moderate PAD
0.00-0.40 Severe PAD

ABI, Ankle-brachial index; PAD, peripheral arterial disease.

Modified from Hiatt WR: Medical treatment of peripheral arterial disease and claudication, N Engl J Med 344:1608-1621, 2001.

5. What are the recommended medical therapies and lifestyle interventions in patients with lower extremity PAD?

    A supervised exercise regimen is recommended as the initial treatment modality for patients with intermittent claudication. Supervised exercise training is recommended over unsupervised exercise training. Cilostazol treatment can lead to a modest increase in exercise capacity. Because agents with similar biologic effects have been shown to increase mortality in patients with heart failure, this drug should not be used in patients with heart failure. Smoking cessation must be strongly emphasized to the patient. Other measures include general secondary prevention interventions. Recommended medical therapies and lifestyle interventions in patients with lower extremity PAD are summarized in Box 55-1. An algorithm for the management of patients with suspected peripheral arterial disease is presented in Figure 55-1.

Box 55-1   RECOMMENDED MEDICAL THERAPIES AND LIFESTYLE INTERVENTIONS IN PATIENTS WITH LOWER EXTREMITY PERIPHERAL ARTERIAL DISEASE

image Statin treatment to lower LDL level to <70-100 mg/dL

image Antihypertensive therapy to lower blood pressure to <140/90 mm Hg (<130/80 mm Hg in patients with diabetes or those with chronic kidney disease)

image Patients with PAD should be offered smoking cessation interventions.

image Antiplatelet therapy is indicated to reduce the risk of MI, stroke, or vascular death.

image Supervised exercise training is the recommended initial treatment modality for intermittent claudication.

image Cilostazol (100 mg orally twice a day) is recommended to improve symptoms and increase walking distance in patients with intermittent claudication. (Cilostazol should not be used in patients with heart failure.)

ACE, Angiotensin-converting enzyme; β-blocker; beta-adrenergic blocking agent; LDL, low-density lipoprotein; MI, myocardial infarction; PAD, peripheral arterial disease.

Modified from Hirsch AT, Haskal ZJ, Hertzer NR, et al: ACC/AHA guidelines for the management of patients with peripheral arterial disease, J Am Coll Cardiol 47(6):1239-1312, 2006.

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