A laboratory model for the evaluation of thromboembolic complications of small diameter vascular prostheses.

Seventeen 2 mm and twenty-five 3 mm internal diameter petrafluoroethylene (PTFE) vascular prostheses were inserted as aortic interposition grafts in 42 rabbits. The 3 month patency with 2 mm grafts was disappointingly low at 24% whereas patency with 3 mm grafts was 82%, comparable to other studies of small diameter prostheses. Hind limb paralysis occurred in 18 animals and proved a reliable indicator of graft thrombosis. Unexpected and previously unreported lower limb ulceration occurred in nine of the 23 long term survivors. Angiographic studies indicated that these ulcers were due to distal embolization of loosely attached mural thrombi. These were found in four of eight patent grafts removed from animals with leg ulcers. Aortic grafting in the rabbit is an economic model for the study of thromboembolic phenomena in small diameter vascular prostheses and their modification by pharmacological agents.