Nonanastomotic aneurysms in venous homologous grafts and bovine heterografts in femoropopliteal bypasses.

In the absence of a suitable autologous vein for a long distal femoropopliteal bypass, the homologous vein appears to be a good substitute. However, the patency rate after one year is less than 50 per cent and nonanastomotic aneurysms occurred in one third of our patients followed for more than one year. These two complications may be related to an immune response which may be lessened by preservation of the graft in the frozen state. Bovine heterografts function well when placed subfascially for femoropopliteal bypasses ending above the knee. Failure rate is high when the distal end of the graft extends across the knee joint. In our experience nonanastomotic aneurysms have developed in 50 per cent of patent grafts followed for more than one year, although other surgeons have reported an incidence of only 3 to 20 per cent. In the follow-up of twenty-three venous homografts and twenty bovine heterografts placed as femoropopliteal bypasses, eight nonanastomotic aneurysms appeared and required replacement. This occurrence was noted in more than 33 per cent of grafts patent beyond one year. When an adequate autologous vein is not available, the composite Dacron-vein graft is the best substitute.