Should polytetrafluoroethylene grafts be used in preference to saphenous vein for femoropopliteal arterial bypass?

Are femorodistal bypass grafts for acute limb ischemia worthwhile?

Background: It has been shown that autogenous veins are associated with the best limb salvage rates for femorodistal bypass surgery. However, in emergency settings, when an autogenous vein is unavailable, use of synthetic graft material or amputation is a critical decision to make. Objective: To assess the appropriateness of femorodistal bypass grafts for acute limb ischemia in emergency settings. Methods: Patients who underwent emergent bypass and elective femorodistal bypass surgery between 1996 and 2006 were reviewed retrospectively in a single center. Results: There were 147 patients of which 84 had elective and 63 had emergent bypass. The graft patency rates for elective admissions were 44 and 25% vs. 25 and 23% for admissions for acute femorodistal graft surgery at 2 and 4 years, respectively (p < 0.004). Admissions for acute ischemia who were treated with prosthetic grafts had a primary patency of 24 vs. 27% for vein grafts at 2 years and 24 vs. 23% at 4 years (p = 0.33). In the acute femorodistal grafts group, primary patency at 2 years for vein and prosthetic grafts was 27 and 24% as compared to 42 and 32% for electives. These values for cumulative limb salvage rates for elective bypasses were 73 and 63% as compared to 52% at both time points in the acute femorodistal graft group (p < 0.004). In emergency settings, the limb salvage rate for acute femorodistal bypass with prosthetic grafts was 38%, and for vein grafts it was 62% at both time points (p = 0.08). Conclusion: The long term limb salvage rate of 38% suggests that emergent femorodistal revascularization is worthwhile.

Saphenous Vein Versus PTFE for Above-Knee Femoropopliteal Bypass. A Review of the Literature

The autogenous saphenous vein is considered the best bypass graft material for arterial bypasses below the inguinal ligament. However, a synthetic graft or prosthesis is considered an acceptable alternative, especially when the distal anastomosis is situated above the knee. Some studies even suggest that patency rates for vein and synthetic grafts are comparable, whereas others indicate that a vein graft is superior to a prosthetic graft, even above the knee. To test the hypothesis that both vein grafts and synthetic prostheses are equally beneficial in the above-knee position, we performed a systematic review of available studies comparing the patency of saphenous vein and polytetrafluoroethylene (PTFE) as bypass material. English and German medical literature from 1966 to 2002 was searched using Medline, and 25 articles meeting our inclusion and exclusion criteria were selected. The patency of venous bypasses was superior to that of PTFE bypasses at all time intervals studied. After 2 years, the primary patency rate of venous bypasses was 81% as compared to 67% for PTFE bypasses, and after 5 years it was 69 and 49%, respectively. After 5 years, the secondary patency of PTFE bypasses reached 60%. When only randomized trials were considered, venous bypasses were again superior to PTFE bypasses at all intervals studied. After 2 years, the primary patency rate of venous and PTFE bypasses was 80 and 69%, respectively, and after 5 years it was 74 and 39%, respectively. Since both randomized and retrospective studies comparing venous with PTFE bypasses showed that vein grafts were 'better' than PTFE prostheses, the null hypothesis that there is no difference between the two types of graft material was rejected (p=0.008). We conclude from this systematic review that if a saphenous vein is available, a venous bypass should be chosen at all times, even if patients have an anticipated short life expectancy (<2 years). If the saphenous vein is absent or not suitable for bypass grafting, PTFE is a good alternative as bypass material.

Influence of a vein cuff on polytetrafluoroethylene grafts for primary femoropopliteal bypass

A retrospective investigation was performed to study the benefit obtained from a vein cuff inserted at the distal anastomosis of a primary femoropopliteal bypass graft with polytetrafluoroethylene (PTFE). When PTFE was preferred to vein an attempt was made to assess whether there was subsequent use for the spared vein. A series of 559 primary PTFE bypasses was studied and found to have a cumulative patency rate of 62 per cent at 36 months. Subgroups were also studied for a similar period. In the above-knee position there was no difference in the primary patency rate of PTFE with or without a cuff at 36 months (69 versus 68 per cent, P = 0.89). Below the knee, grafts with a cuff had a better 36-month patency rate than those without (57 versus 29 per cent, P = 0.01). Cuffed PTFE for claudication had a better patency rate than that for threatened limbs at 36 months (68 versus 60 per cent, P = 0.03). Thrombectomy of occluded cuffed PTFE grafts improved the 36-month patency rate from 64 to 74 per cent. The limb salvage rate at 36 months was 97 per cent for claudication and 89 per cent for threatened limbs with cuffed PTFE. Occlusion of cuffed PTFE was associated with preservation of outflow in 91 (51 per cent) of 179 cases, permitting subsequent graft thrombectomy or insertion of a new bypass. Spared vein was rarely used to salvage an occluded PTFE graft, and was associated with poor patency and a high amputation rate. Although this study does not support the use of PTFE for the primary graft, PTFE with a vein cuff interposed at the distal anastomosis is a reasonable substitute when vein is not available.