Patient and donor characteristics which influence patency rates of cryopreserved conduits used in lower extremity limb salvage
Aaron Hayson, Panagiotis Koutakis, Derek Hillison, Adam Bullock, Ahmed Ismaeel, Dan Kaelin, Denise Smith, Robert Brumberg
Vascular Surgery Associates, Tallahassee, FL
INTRODUCTION: Autologous vein harvest is the preferred bypass conduit. It is well known that patency rates for lower extremity bypass is far lower for non-autologous venous conduits. There are instances which autologous vein is not available for bypass and a biological tissue alternative is desired. Cryopreserved conduits are increasingly used for lower extremity limb salvage with suboptimal results. Recent vascular studies have indicated that certain donor and patient characteristics may play a role in patency rates of cryopreserved conduits. The goal of our study is to examine certain donor and patient characteristics and their role in improving patency rates for this subset of vascular patients.
METHODS: Clinical data for all patients that were bypassed with a cryopreserved conduit were recorded between the years of 2011 - 2018. Patient risk factors, age, date of bypass, indication, gender, type of procedure, preoperative and postoperative anticoagulation, compliance with duplex surveillance as well as rationale for cryopreserved conduit were all recorded. The donor serial numbers were queried for blood type, warm ischemia time, cold ischemia time, age, gender and cryopreserved conduit type. Primary outcomes of the bypassed conduits were patency rate and limb salvage. Time of patency rates and limb salvage were analyzed with Kaplan Meier curves and a Cox stepwise regression model for hazard ratios was used to determine risk-adjusted predictors of patency and limb salvage.
RESULTS: A total of 65 patients underwent lower extremity bypass with cryopreserved conduits (14 femoral arteries and 51 saphenous veins). All 65 patients underwent outflow procedures with the majority, 63 patients, having infrageniculate bypasses with > 90% for rest pain and tissue loss. The median age of our cohort was 67.2 years of age. The median time for first ultrasound graft scan for all bypasses was 94 days. Kaplan-Meier demonstrated an overall 1-year primary, primary assisted and secondary patency rate of all cryo-saphenous vein conduits was 18.3%, 60.9% and 57.4% respectively. Primary, primary assisted and secondary patency at 1 year for the femoral arteries was 10.2%, 22.2% and 40% respectively. The 1-year amputation free survival rate for all conduits was 80.6%. There was no significant difference in primary patency rates between the cryopreserved artery and vein bypass. Of the forty-two grafts that failed at primary patency, 19 (45%) had Rh mismatch and 12 grafts (20%) were occluded at 30 days. Only 7 (16%) complied with required duplex ultrasound at 30 days in which these bypasses were patent. Factors associated with a loss of primary patency were CAD (p=0.028), obesity (p=0.006), age of conduit >33years of age (p=0.13) and Rh mis-match (p=0.04).
CONCLUSIONS: From our cohort, early graft failure of cryopreserved bypasses is common. Unmatched Rh factor of patient’s and donor’s blood type was associated with increased risk-adjusted loss of primary patency. Lack of early duplex ultrasound was associated with primary graft failure regardless of type of conduit. Vascular surgeons must be cognizant that Rh mismatch, type and age of conduit and early duplex surveillance are key factors affecting the viability of cryopreserved lower extremity bypass.
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