Key Clinical Updates in Occlusive Disease: Femoral & Popliteal Arteries
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ESSENTIALS OF DIAGNOSIS
Cramping pain or tiredness in the calf with exercise.
Reduced popliteal and pedal pulses.
Foot pain at rest, relieved by dependency.
Foot gangrene or ischemic ulcers.
The superficial femoral artery is the peripheral artery most commonly occluded by atherosclerosis. Atherosclerosis of the femoral-popliteal segment usually occurs about a decade after the development of aortoiliac disease, has an even gender distribution, and commonly affects black and Hispanic patients. The disease frequently occurs where the superficial femoral artery passes through the abductor magnus tendon in the distal thigh (Hunter canal). The common femoral artery and the popliteal artery are less commonly diseased but lesions in these vessels are debilitating, resulting in short-distance claudication.
Symptoms of intermittent claudication caused by lesions of the common femoral artery, superficial femoral artery, and popliteal artery are confined to the calf. Claudication occurs at 2–4 blocks when there is occlusion or stenosis of the superficial femoral artery at the adductor canal, provided good collateral vessels from the profunda femoris are maintained (eFigure 12–2). However, with concomitant disease of the profunda femoris or the popliteal artery, much shorter distances may trigger symptoms. With short-distance claudication, dependent rubor of the foot with blanching on elevation may be present. Chronic low blood flow states will also cause atrophic changes in the lower leg and foot with loss of hair, thinning of the skin and subcutaneous tissues, and disuse atrophy of the muscles. With segmental occlusive disease of the superficial femoral artery, the common femoral pulsation is normal, but the popliteal and pedal pulses are reduced.
Magnetic resonance angiography of the lower extremity demonstrating preocclusive disease of the superficial femoral artery on the right and occlusion on the left. The left profunda femoris artery is the source of a rich collateral network in this patient.
B. Doppler and Vascular Findings
ABI values less than 0.9 are diagnostic of PAD and levels below 0.4 suggest chronic limb-threatening ischemia (formerly critical limb ischemia). ABI readings depend on arterial compression. Since the vessels may be calcified in diabetes mellitus, chronic kidney disease, and in older adults, ABIs can be misleading. In such patients, the toe-brachial index is usually reliable with a value less than 0.7 considered diagnostic of PAD. Pulse volume recordings with cuffs placed at the high thigh, mid-thigh, calf, and ankle will delineate the levels of obstruction with reduced pressures and blunted waveforms.