Predictors of success in bypass grafts to the isolated popliteal segment

Of 130 infrainguinal bypasses, 25 grafts to an isolated popliteal segment (IPS) were examined for clinical, anatomic and hemodynamic predictors of success. Fourteen autogenous veins (AV) and 11 polytetrafluoroethylene (PTFE) grafts were performed, all for limb salvage. A discontinuous tibial vessel was present in 72 per cent but only 24 per cent were graftable. A mean of 1.7 named collaterals were seen in IPS. Mean preoperative ankle pressure (APR) was 26.29 and ankle to brachial index (ABI) was 0.17. Segmental pressure gradient indices were also measured. Mean follow-up time was 13.6 months (a range of two to 43 months). One hundred per cent immediate graft patency and patient survival rates were obtained. Postoperative APR improved to 86.3 millimeters of mercury and ABI to 0.63 (p less than 0.05). Crude late patency rate was 72 per cent and limb salvage rate was 76 per cent. Cumulative life table patency rate was 58.8 per cent and limb salvage was 68 per cent at 36 months. Patency rate for AV (84.1 per cent) was better than PTFE (41.7 per cent). In 39 concurrent tibial grafts, cumulative patency rate at 36 months was 68 per cent for simple bypass grafts. Success could not be predicted by the length of the IPS, number of collaterals, profunda disease, number of discontinuous or graftable tibial vessels, APR or ABI and profunda popliteal collateral index. The tibial gradient index reflecting poor runoff was significantly greater in failed grafts (p less than 0.05). Bypass grafts to the IPS are a safe and reliable alternative to tibial bypass grafts. The AV performed better than PTFE grafts. The tibial gradient index appears to be a promising indicator for predicting graft success.