Increased warm ischemia time during vessel harvest decreases the primary patency of cryopreserved conduits in patients undergoing lower extremity bypass

Abstract

Objective: Autologous vein is the preferred conduit for lower extremity bypass. However, it is often unavailable because of prior harvest or inadequate for bypass owing to insufficient caliber. Cryopreserved cadaveric vessels can be used as conduits for lower extremity revascularization when autogenous vein is not available and the use of prosthetic grafts is not appropriate. Many studies have shown that donor characteristics influence clinical outcomes in solid organ transplantation, but little is known regarding their impact in vascular surgery. The purpose of this study was to examine the effects donor variables have on patients undergoing lower extremity bypass with cryopreserved vessels.

Methods: The tissue processing organization was queried for donor blood type, warm ischemia times (WITs), and serial numbers of cryopreserved vessels implanted at a single center from 2010 to 2016. The serial numbers were then matched with their respective patients using the institutional Clinical Data Repository and patient data were obtained from the Clinical Data Repository and chart review. Primary outcomes were primary patency of the bypass conduits and limb salvage. Time to loss of patency was evaluated using Kaplan-Meier methods and a Cox proportional hazards model determined risk-adjusted predictors of patency and limb salvage.

Results: Sixty patients underwent lower extremity bypass with 65 cryopreserved vessels (23 superficial femoral arteries, 41 saphenous veins, 1 femoral vein). Thirty-eight procedures were reoperations. There were 21 inflow, 44 outflow, and 44 infrainguinal procedures. Preexisting comorbidities did not differ significantly between those who lost patency and those who did not. The mean WIT among the entire cohort was 892.3 ± 389.1 minutes (range, 158.0-1434.0 minutes). The median follow-up was 394 days. Kaplan-Meier analysis demonstrated an overall 1-year primary patency rate of 51%. Primary patency at 1 year was 67% and 41% for inflow and outflow procedures, respectively, and did not differ significantly between the two groups (P = .15). Donor-to-recipient ABO incompatibility was not associated with loss of primary patency. The 1-year amputation-free survival was 74%. Primary patency significantly decreased with each hourly increase in WIT on risk-adjusted analysis (hazard ratio, 1.1; P = .02).

Conclusions: Higher cryopreserved vessel WIT was associated with increased risk-adjusted loss of primary patency in this cohort. At 1 year, the overall primary patency was 51% and amputation-free survival was 74%. Vascular surgeons should be aware that WIT may affect outcomes for lower extremity bypass.

Keywords: Kaplan-Meier estimate; Limb salvage; Lower extremity; Proportional hazards models; Tissue transplantation; Vascular grafting; Vascular surgical procedures; Warm ischemia.