Changes in angiographic features and the ankle/brachial pressure index of femorodistal arterial bypass grafts during knee flexion.

Systolic ankle pressure was measured in limbs in the extended and 90 degrees-flexed positions in three groups of patients who had undergone below-knee femorodistal arterial bypass. Group 1 consisted of eight limbs in seven patients who had received an autologous saphenous vein (ASV) graft; group 2 consisted of seven limbs in seven patients who had received a ringed expanded polytetrafluorethylene (ePTFE) graft; and group 3 consisted of five limbs in five patients who had received a reinforced biosynthetic borine collagen vascular (Omniflow) graft. Intravenous digital subtraction angiography was performed within 3 months of implantation. The ankle/brachial index (ABI) was significantly lower when the knee was flexed than when it was extended in group 1 and 3, but not in group 2. The ABI flexion in group 1 was similar to that in group 2. Morphologic changes such as kinking were demonstrated angiographically in groups 1 and 3. Given that the ABIs in groups 1 and 2 were similar with the knee flexed, despite the morphologic changes in group 1, we concluded that saphenous vein and ringed ePTFE grafts are more durable when subjected to acute knee flexion than Omniflow grafts. Thus, as graft failure is unlikely to result from kinking as a result of knee flexion alone, further clinical studies are required to elucidate the precise causes of graft failure.