Platelet accumulation on an artificial surface in vivo: effect of intravascular hemolysis

Studies of thromboembolic complications after implantation of cardiovascular prosthetic devices have suggested that there is a correlation between the occurrence of hemolysis and the way in which platelets respond to an artificial surface. To test this hypothesis, we investigated the effect of low-level hemolysis (involving approximately 1% of the circulating red blood cells [RBCs] per hour) on the number of platelets that accumulated on woven Dacron arterial grafts used to bypass the carotid artery in six dogs. Each dog was used in one control and one test procedure, which were performed in random order. In the test procedures, hemolyzed autologous erythrocytes were infused (1 ml/kg/hr) for 10 minutes before, and during, blood flow through the graft. In the control procedures, physiologic saline solution was substituted for the hemolysate. Autologous indium-111 labeled platelets were used to estimate the number of platelets present on the Dacron surface one hour after the initiation of blood flow through the graft. More platelets accumulated on the Dacron surface in the presence of the hemolysate than in the presence of the saline. The increase caused by hemolysis ranged from 2% to 96%, with a mean of 43.7% +/- 35.9% (standard deviation).