Allograft vein patency in a canine model. Additive effects of cryopreservation and cyclosporine

Autogenous saphenous vein is the preferred conduit for many cardiovascular operations. Attempts to use allograft veins for arterial reconstruction have had poor results. To define circumstances under which allograft veins might prove to be acceptable vascular conduits, dogs underwent femoral artery bypass using reversed saphenous veins. Veins were transplanted fresh or after cryopreservation. Group I dogs received a fresh autograft to replace one femoral artery (group I F) and a cryopreserved (CP) autograft (group I C) to replace the other. Group II dogs received fresh allograft veins, and group III received CP allograft veins, neither group receiving additional treatment. Group IV received fresh allograft veins and Group V received CP allograft veins; both groups received cyclosporine 15 mg/kg. Animals were maintained until grafts occluded or until six months elapsed. Patency was observed in all group I F grafts throughout the observation period. Six-month patency rates in the other groups were: group I C, 9/10 (P = NS vs. group I F); group II, 0/10 (P less than 0.01), group III, 0/10 (P less than 0.01), group IV, 1/10 (P less than 0.01), group V, 7/11 (P = NS). In a separate series of observations 10 cryopreserved allograft veins were implanted in 10 dogs that received CsA for 30 days. CsA was then discontinued. All of these grafts occluded within 30 days of discontinuing the CsA. Long-term patency of saphenous vein allografts was achieved only with the combination of cryopreservation and immunosuppression with continued CsA.