An in vivo method to evaluate the effect of materials upon arterial thrombosis.

An in vivo method to evaluate the effect of materials upon arterial thrombosis was developed that minimized the effect of surgical artifacts and provided a test which was critically sensitive to the surface properties of the materials. The procedure has general applicability to elastomers, either solvent cast or mold polymerized, and involves the implantation of segments of the test materials within canine femoral and carotid arteries. The sensitivity of this technique was demonstrated by comparing two surface preparations of a segmented polyurethane: as-cast and ion sputtered. There was a striking difference in the rate of thrombus development on as-cast polyurethane implants compared with sputtered polyurethane implants. After 1 hr. of implantation the surface of the as-cast polyurethane was covered with a monolayer of platelets and leukocytes, whereas thrombus development progressed more rapidly on the sputtered polyurethane surface and at 1 hr. it was covered with pillars of platelets and leukocytes with fibrin accumulation between pillars. The method was also useful for long-term studies, which showed that a thin layer of thrombus developed on both polyurethane surfaces and by 1 wk. after implantation the surfaces of the thrombi became endothelialized.