An investigation into the causes of failure of PTFE grafts.

In an attempt to improve the results of PTFE bypass grafting in the lower limb, a consecutive series of 159 grafts has been analysed in detail to determine the causes of failure. The majority were performed for limb salvage (76%) and the remainder for severe claudication. Forty-five grafts (28%) were to tibial or peroneal vessels. All patients were studied by preoperative arteriographic and Doppler studies, operative arteriography and postoperative Doppler and vasoscan studies. In selected cases postoperative arteriography was carried out with the knee straight and flexed. Thirty-seven failures occurred during a follow-up period of between 6 months and 6 years. The findings indicated four main causes of failure, extension of disease (30%), anastomotic hyperplasia (19%), graft kinking (13%) and technical faults (5%). Each of these is considered in detail and illustrative examples described. Overall patency rates for all popliteal bypasses (AK 43%; BK 57%) were 90 +/- 3% at one year, 78 +/- 5% at 3 years and 69 +/- 8% at 5 years. Comparable figures for tibial grafts were 86 +/- 6% at one year, and 60 +/- 14% at three years. As a consequence of the study, operative techniques have now been modified and preliminary results indicate that these patency rates can be significantly improved.