Pseudoocclusion of femoropopliteal bypass grafts.

Pseudoocclusion has occurred when a patent graft is mistaken for a thrombosed graft, often because of reduced inflow. We reviewed 13 patients with pseudoocclusion of 14 grafts to analyze the surprising patency of certain grafts in spite of low flow. Two iliopopliteal and 12 femoropopliteal saphenous vein grafts developed pseudoocclusion 6 months to 6 years (mean 2.6 years) after the original procedure. Ten limbs presented with claudication, two with rest pain, and two with nonviable tissue. Femoral pulses were decreased in 13 limbs and distal pulses were absent in all limbs. Graft thrombosis was suspected in all cases. Occlusion proximal to the graft, either iliac (n = 11) or femoral (n = 2), was found in all 13 limbs studied angiographically. Ten limbs had one- or two-vessel runoff, and only three limbs had three-vessel runoff. Pseudoocclusions were corrected with a variety of inflow procedures, with return of pulses and resolution of symptoms in 13 limbs. One failure resulted in major amputation. We concluded that certain grafts will remain patent in spite of greatly reduced inflow and that recurrence of symptoms does not always signify graft thrombosis. Patency in spite of low flow could not be related to runoff, and autogenous vein appeared to be the graft material most tolerant of low flow.