Alloplastic bypass material below the knee: actual rationale

The greater saphenous vein is considered as material of first choice for a below-knee bypass. A high number of below knee synthetic, polytetrafluoroethylene or knitted polyester, bypass grafts in the institution of the senior author formed the basis to analyze factors for outcome of below-knee synthetic grafts.

A total of 533 patients (327 men, 206 women; age: 71.2 ± 10.3 years), who had their first below knee bypass, were followed-up for up-to 9 (4.1 ± 2.6) years. Survival, primary and secondary patency, and limb salvage were compared between vein bypasses and synthetic grafts by Kaplan Meier analysis. Within the group of 377 patients with synthetic grafts comorbidities, previous interventions, indications, graft diameter, and technical aspects were related to outcome including univariate (log-rank) and multivariate (Cox Proportional Hazard Ratio) statistics.

The greater saphenous vein was superior to synthetic graft in primary and secondary patency as well as limb salvage (5 year limb salvage 73.3% vs. 56.7%, P=0.001). In patients with a synthetic bypass, relevant preoperative factors for higher patency rates were hypertension, coronary heart disease and no previous endovascular intervention. Patency and limb salvage was significantly improved for anastomoses not to a single crural vessel. Adding a St. Mary's Boot as cuff technique did not improve the results. In multivariate analysis, independent factors for higher primary patency were no previous endovascular intervention, low severity of peripheral arterial occlusive disease, coronary heart disease and age above 65. Additionally, femoropopliteal and tibioperoneal anastomoses were related to better limb salvage.

The greater saphenous vein reveals the best results for below-knee bypass grafts. However, if a vein is not available, synthetic grafts appear to be an valuable alternative especially in patients with no previous radiologic intervention, coronary heart disease, and age over 65.