Venous thrombosis on prosthetic surfaces. Evolution and blood coagulation studies in a nonhuman primate model.

Thrombi deposited on prosthetic devices in the superior vena cava of the rhesus monkey were studied by morphologic and biochemical technics. Glass or silicone-coated glass (SCG) rings were implanted for 30 minutes to 14 days. Thrombus was deposited on the surface of each prosthetic device, and deposition was much greater and more rapid on glass surfaces than on SCG surfaces. On SCG surfaces, initial deposits consisting of single platelets, small platelet aggregates and erythrocytes were seen by scanning electron microscopy. These were followed by larger platelet aggregates, fibrin and, much later, leukocytes. Transmission electron micrographs revealed disintegration of the platelets forming aggregates and an osmiophilic deposit on the prosthetic surface. Shortened partial thromboplastin times were observed in all test animals but the sham-operated one, and therefore may be predictive of thrombus formation.