Value of segmental limb blood pressures in predicting results of aortofemoral bypass

The efficacy of segmental limb blood pressure measurements, assessed noninvasively by Doppler ultrasound, in predicting the result of aortofemoral reconstruction was evaluated in fifty-two extremities with varying extent of aortoiliac and more distal arterial occlusive disease. Three prognostic correlates were analyzed: (1) preoperative proximal thigh/arm pressure index (TPI); (2) preoperative pressure gradient between adjacent leg segments (proximal thigh, above-knee, below-knee, and ankle), normally less than 30 mm Hg; and (3) early postoperative increase in the ankle/arm pressure index (API). After aortofemoral bypass, forty-one limbs (79 per cent) were asymptomatic or improved and eleven were unimproved. The mean TPI in extremities benefiting from aortofemoral bypass, 0.82 ± 0.17 (±1SD) was significantly less than that of unimproved limbs, 1.01 ± 0.09 (p < 0.01). Aortofemoral bypass was beneficial in all twenty limbs with normal leg pressure gradients. Conversely, six of twenty-five legs with one abnormal gradient and five of seven with two abnormal gradients failed to improve. The postoperative increase in API was 0.1 or more in all forty-one improved extremities and was less than 0.1 in all eleven failures. Although eleven of thirty-two limbs (34 per cent) with arteriographic evidence of combined aortoiliac and subinguinal occlusive disease were not improved after proximal bypass, the result of operation could not be predicted from the angiographic pattern or severity of distal disease. Segmental limb blood pressures provide useful predictive indices of the efficacy of aortofemoral bypass and the potential need for more distal reconstruction in multisegmental disease.