ATHEROSCLEROTIC PERIPHERALVASCULAR DISEASE
OCCLUSIVE DISEASE: AORTA & ILIAC ARTERIES
ESSENTIALS OF DIAGNOSIS
Claudication: cramping pain or tiredness in the calf, thigh, or hip while walking.
Diminished femoral pulses.
Tissue loss (ulceration, gangrene) or rest pain.
Occlusive atherosclerotic lesions developing in the extremities, or peripheral arterial disease (PAD), is evidence of a systemic atherosclerotic process. Pathologic changes of atherosclerosis may be diffuse, but flow-limiting stenoses occur segmentally. In the lower extremities, they classically occur in three anatomic segments: the aortoiliac segment (eFigure 12–1), femoral-popliteal segment, and the infrapopliteal or tibial segment of the arterial tree. Each with its own population demographic, lesions in the distal aorta and proximal common iliac arteries classically occur in white male smokers aged 50–60 years. The aortoiliac disease may be the initial manifestation of systemic atherosclerosis. Disease progression may lead to complete occlusion of one or both common iliac arteries, which can precipitate occlusion of the entire abdominal aorta to the level of the renal arteries. Lesions affecting the external iliac arteries are less common as are lesions isolated to the aorta. This is particularly true of younger patients with isolated aortoiliac disease, ie, with no involvement of the more distal vessels of the lower extremities.
Magnetic resonance angiography showing atherosclerotic occlusive disease of the aortoiliac segment. The vessels proximally and distally are relatively unaffected.
Pain occurs because blood flow cannot keep up with the increased demand of exercise. This pain, termed “claudication,” is typically described as severe and cramping and primarily occurs in the calf muscles. The pain from aorto-iliac lesions may extend into the thigh and buttocks with continued exercise and erectile dysfunction may occur from bilateral common iliac disease. Although generally reproducible, there is day-to-day variation in severity, thus the term, “intermittent claudication.” Rarely, patients complain only of weakness in the legs when walking, or simply extreme limb fatigue. The symptoms are relieved with rest. Femoral pulses are absent or very weak as are the distal pulses. A bruit may be heard over the aorta, iliac, or femoral arteries or over all three arteries.
B. Doppler and Vascular Findings
The ratio of systolic blood pressure detected by Doppler examination at the ankle compared with the brachial artery (referred to as the ankle-brachial index [ABI]) is reduced to below 0.9 (normal ratio is 1.0–1.2); this difference is exaggerated by exercise. Both the dorsalis pedis and the posterior tibial arteries are measured and the higher of the two artery pressures is used for calculation. Segmental waveforms or pulse volume recordings obtained by strain gauge technology through blood pressure cuffs demonstrate blunting of the arterial inflow throughout the lower extremity.