Comparison of Precuffed and Vein-Cuffed Expanded Polytetrafluoroethylene Grafts for Infragenicular Arterial Reconstructions: A Case-Matched Study

Comparison of graft patency, limb salvage, and antithrombotic therapy between prosthetic and autogenous below-knee bypass for critical limb ischemia

BACKGROUND

The autogenous vein is the preferred conduit in below-knee vascular reconstructions. However, many argue that prosthetic grafts can perform well in crural bypass with adjunctive antithrombotic therapy. We therefore compared outcomes of below-knee prosthetic versus autologous vein bypass grafts for critical limb ischemia and the use of adjunctive antithrombotic therapy in both settings.

METHODS

Utilizing the registry of the Vascular Study Group of New England (2003-2009), we studied 1227 patients who underwent below-knee bypass for critical limb ischemia, 223 of whom received a prosthetic graft to the below-knee popliteal artery (70%) or more distal target (30%). We used propensity matching to identify a patient cohort receiving single-segment saphenous vein yet had remained similar to the prosthetic cohort in terms of characteristics, graft origin/target, and antithrombotic regimen. Main outcome measures were graft patency and major limb amputation within 1 year. Secondary outcomes were bleeding complications (reoperation or transfusion) and mortality. We performed comparisons by conduit type and by antithrombotic therapy.

RESULTS

Patients receiving prosthetic conduit were more likely to be treated with warfarin than those with greater saphenous vein (57% vs. 24%, P<0.001). After propensity score matching, we found no significant difference in primary graft patency (72% vs. 73%, P=0.81) or major amputation rates (17% vs. 13%, P=0.31) between prosthetic and single-segment saphenous vein grafts. In a subanalysis of grafts to tibial versus popliteal targets, we noted equivalent primary patency and amputation rates between prosthetic and venous conduits. Whereas overall 1-year prosthetic graft patency rates varied from 51% (aspirin+clopidogrel) to 78% (aspirin+warfarin), no significant differences were seen in primary patency or major amputation rates by antithrombotic therapy (P=0.32 and 0.17, respectively). Further, the incidence of bleeding complications and 1-year mortality did not differ by conduit type or antithrombotic regimen in the propensity-matched analysis.

CONCLUSIONS

Although limited in size, our study demonstrates that, with appropriate patient selection and antithrombotic therapy, 1-year outcomes for below-knee prosthetic bypass grafting can be comparable to those for greater saphenous vein conduit.

Mid- and long-term results of the treatment of infrainguinal arterial occlusive disease with precuffed expanded polytetrafluoroethylene grafts compared with vein grafts

BACKGROUND

Prosthetic grafts for lower-extremity bypass have limited patency compared with autologous vein grafts. Precuffed expanded polytetrafluoroethylene (ePTFE) grafts alter the geometry of the distal hood to improve patency. This study reports the authors' long-term results on the use of precuffed ePTFE grafts for infrainguinal bypasses in patients with arterial occlusive disease and compares these with results of reversed great saphenous vein grafts (rSVG).

METHODS

A retrospective review of billing codes identified 101 polytetrafluoroethylene (PTFE) and 47 rSVG bypasses performed over a 6-year period. Femoral to below-knee popliteal and femoral to tibial bypasses were analyzed. Data collected consisted of risk factors, Rutherford classification, bypass inflow and outflow, runoff vessels, patency, amputation, and death. Primary end points consisted of primary, assisted-primary, and secondary patency along with limb salvage.

RESULTS

Mean age of the patients was 76 years in the PTFE group and 69.8 years in the rSVG group. For femoral to below-knee popliteal bypasses, primary patency at 1, 3, and 5 years in the PTFE group was 76.9%, 48.7%, and 43.3%, respectively, compared with 77.1%, 77.1%, and 77.1%, respectively, in the rSVG group (P = 0.225). Secondary patency was 89.2%, 70.9%, and 50.6% in the PTFE group compared with 84.4%, 84.4%, and 84.4% in the rSVG group (P = 0.269). Limb salvage was similar in the PTFE compared with the rSVG group (97.7%, 90.5%, and 79.4% vs. 83.3%, 83.3%, and 83.3%; P = 0.653). For femoral to tibial bypasses, primary patency in the PTFE group at 1, 3, and 5 years was 57.1%, 40.4%, and 22.1%, respectively, compared with 67.4%, 67.4%, and 50.6%, respectively, for the rSVG group (P = 0.246). Secondary patency was 75.5%, 44.9%, and 22.7% in the PTFE group compared with 91.8%, 91.8%, and 52.5% in the rSVG group (P = 0.022). Limb salvage at 1, 3, and 5 years was 79.2%, 55.7%, and 55.7%, respectively, in the PTFE group compared with 96.4%, 96.4%, and 64.3%, respectively, in the rSVG group (P = 0.046).

CONCLUSIONS

Precuffed ePTFE grafts demonstrate similar 1-year patency to that of rSVG. However, mid- and long-term patency is reduced compared with saphenous vein grafts (SVG), especially to tibial targets. PTFE grafts to the popliteal demonstrate limb salvage rates similar to those of SVG. In the tibial vessels, limb salvage rates for PTFE grafts are significantly worse compared with SVG.

Early Results for Below-Knee Bypasses Using Distaflo

In patients who require lower extremity revascularization, prosthetic graft is a reasonable alternative in the absence of a suitable autologous vein conduit. However, prosthetic bypass grafts have limited patency, especially for infrageniculate reconstruction. Polytetrafluoroethylene grafts were geometrically modified at the distal end to increase their patency. The authors reviewed their experience with the Distaflo graft in patients who required lower extremity below-knee popliteal and tibial bypasses when no suitable autologous vein conduit was available. Chart review was conducted of the 57 patients who underwent 60 lower extremity bypasses over a 3-year period between June 2003 and April 2006. Twenty-four revascularizations were constructed to the tibial outflow sites, whereas the remaining grafts were placed to the below-knee (28) and above-knee (8) popliteal artery, respectively. Study endpoints were primary, assisted primary, secondary patency, and limb salvage at the time of follow-up. Distaflo bypass was performed at the infrageniculate level in 86.7% of cases (28 below-knee popliteal, 24 tibial). Mean follow-up time was 12 months (range, 0.5-37.5 months). At 1 year, primary, assisted primary, and secondary patencies and limb salvage rates for below-knee popliteal bypasses were 83.5%, 89.5%, 94.7%, and 94.4%, respectively. Primary, assisted primary, and secondary patencies and limb salvage rates for tibial bypasses were 44.4%, 44.4%, 63.2%, and 74.9%, respectively. Distaflo precuffed graft is a good alternative conduit for below-knee popliteal and tibial lower extremity reconstructions in the absence of an autologous vein and appears to have promising early patency and limb salvage rates even when used for tibial bypasses.

Systematic review of preservation methods and clinical outcome of infrainguinal vascular allografts

OBJECTIVE

We systematically reviewed clinical studies on the use of venous and arterial allografts for infrainguinal revascularization. We attempted to find evidence for the best infrainguinal vascular allograft by a systematic review of the available literature.

METHODS

An electronic search of the MEDLINE, EMBASE, and Cochrane databases was used to determine key articles from studies on the different types of vascular allografts used in infrainguinal reconstruction from 1966 to 2004. Articles were independently reviewed by using previously defined inclusion and exclusion criteria. Study results were gathered with cumulative primary patency as the primary end point. Secondary end points were major complications, graft disintegration, and major limb loss. Quantitative analysis was performed on the prospective randomized trials, and linear regression analysis was performed on cumulative primary patency. Fontaine's classification system was applied.

RESULTS

No systematic review of randomized controlled trials was found. Five randomized controlled trials, 3 prospective cohort or case series, and 15 retrospective case series with 3,837 vascular allografts were found. Methods of allograft preservation were cryopreservation (5 studies), cold storage (3 studies), and glutaraldehyde preservation of human umbilical veins (15 studies). One-year cumulative primary patency rates were 13% to 79% for cryopreservation, 63% to 80% for cold storage, and 40% to 91% for glutaraldehyde. The weighted mean 1-year cumulative primary graft patency rate was 41% for cryopreservation, 71% for cold storage, and 70% for glutaraldehyde allografts. Four randomized trials on femoropopliteal bypasses demonstrated higher patency rates of glutaraldehyde-preserved human umbilical veins than polytetrafluoroethylene grafts. Statistical heterogeneity between studies (I(2) = 91.4%) was too high to perform a formal meta-analysis. The rate of major limb loss was 20% to 58% for cryopreservation, 10% to 69% for cold storage, and 0% to 65% for glutaraldehyde, and the percentage of graft disintegration was 2% to 6% for cryopreservation, 4% to 15% for cold storage, and 0% to 11% for glutaraldehyde.

CONCLUSIONS

A firm conclusion could not be made because there were no studies available in which direct comparison was performed between different preservation methods of vascular allografts. In addition, heterogeneity of the individual studies hampered direct comparison of different types of vascular allografts. However, the overall graft performance of glutaraldehyde-preserved human umbilical vein allografts may be superior to that of other vascular allografts.