Noninvasive predictors of patency for infrapopliteal PTFE bypasses with combined arteriovenous fistula and vein interposition technique☆

Abstract 

Background: Despite recent increased indications for infrapopliteal prosthetic bypass grafts with complementary arteriovenous fistulas, objective documentation of improved perfusion to the foot is lacking. In addition, the value of post-operative noninvasive testing in the prediction of bypass success remains unclear.

Patients and methods: Over a 3-year period, 41 patients with limb-threatening ischemia were treated with 41 infrapopliteal 6-mm polytetrafluoroethylene (PTFE) bypasses with a complementary arteriovenous fistula at our institution. Twenty-four patients were men and 17 were women, with an average age of 71.3 ± 8.6 years. Thirty-one patients (76%) had undergone at least 1 previous failed ipsilateral arterial bypass. Preoperative and early postoperative (less than 1 month) pulse-volume recordings of transmetatarsal amplitude (TMA) were available for analysis in 28 patients. Postoperative duplex evaluations of graft velocity, fistula patency, and prograde distal arterial flow were performed in 26 of the original 41 patients. These data were correlated to early graft failure in an attempt to identify specific noninvasive predictors.

Results: Cumulative primary patency rates of the original 41 patients were 79.0%, 69.2%, and 63.8% at 1, 2, and 3 years, respectively. The early postoperative TMA values ranged from 3 to 50 mm with a mean of 21.6 ± 14.8 mm (P < 0.001). Twenty-one patients (75%) had patent grafts on follow-up of 2 to 37 months (mean 18.6). The early postoperative TMA in this group of patients was 26.5 ± 12.4 mm compared with 3.3 ± 2.8 mm in the 6 patients whose grafts failed within 6 months (P < 0.001). A TMA of <5 mm was 83% sensitive and 95% specific for the prediction of early graft failure. Of the grafts examined by duplex ultrasonography, 21 (81%) remained patent during the follow-up period. The midgraft peak systolic velocity (PSV) of these grafts was 109 ± 8.0 cm/s compared with 74.2 ± 15.3 cm/s for the 5 initially patent bypasses that subsequently failed at any time during the follow-up period (P < 0.05). PSV of <70 cm/s was 60% sensitive and 86% specific in predicting early graft failure. The combination of early postoperative TMA <5 mm and early midgraft PSV <70 cm/s was 100% sensitive and 100% specific for the prediction of early graft failure.

Conclusions: These data show that infrapopliteal PTFE arterial bypasses with complementary arteriovenous fistulas significantly improve arterial perfusion at the level of the foot in the majority of patients. Also, both the postoperative TMA and midgraft PSV appear to be reliable predictors of graft outcome. Further experience with the noninvasive surveillance of these bypasses may become as rewarding as it is in standard vein bypasses.

No full text is available. To read the body of this article, please view the PDF online.