Infrapopliteal polytetrafluoroethylene and composite bypass: factors influencing patency.

Between January 1, 1979, and December 31, 1988, 149 infrapopliteal polytetrafluoroethylene (PTFE) bypasses were performed in 145 patients with chronic, critical, limb-threatening ischemia. These operations represented 27.9% of 534 infrapopliteal bypasses performed during the same period. There were 92 males and 53 females. Mean age was 71.8 +/- 12.3 years. Signs and symptoms of critical ischemia were gangrene, ulceration, and isolated rest pain in 101 (69%), 23 (15.3%), and 25 (16.7%) cases, respectively. A composite (PTFE-saphenous vein) graft was used in 53 (35%) cases. In 96 prosthetic bypasses the distal anastomosis was performed using vein patch angioplasty in 65 (44%) cases and directly in 31 (21%). The in-hospital mortality rate was 3.3%. Patency, limb salvage, and patient survival rates were plotted according to the actuarial method and the curves obtained were compared using the log-rank test. Actuarial survival rates were 68% +/- 5% and 57% +/- 7% at 3 and 5 years, respectively. Primary patency and lower limb salvage rates were 41% +/- 5% and 68% +/- 6% at 3 years and 35% +/- 9% and 65% +/- 10% at 5 years, respectively. There was no statistically significant difference noted in primary patency rates at 3 years according to the type of bypass (composite or all-prosthetic: 36% vs. 44%), the type of distal anastomosis (direct or vein patch angioplasty: 43% vs. 45%), the site of distal anastomosis (upper or lower half of the leg: 38% vs. 46%), lateral or medial placement of the bypass (39% vs. 43%), or according to whether or not it was a repeat operation (40% vs. 44%). In conclusion, patency rates using infrapopliteal PTFE bypasses are low. Certain technical approaches, although they do not seem to improve patency, definitely increase the feasibility of bypass and in our opinion decrease the risk of early failure in unfavorable anatomic settings. The limb salvage rates following infrapopliteal PTFE and composite bypass are encouraging and justify the use of routine distal revascularization, even in the absence of autogenous vein graft.