Effect of heparin and prostacyclin/heparin infusion on platelet aggregation in hemodialyzed patients.

The number of circulating platelet aggregates determined according to the method of Wu and Hoak and the platelet morphology revealed by scanning electron microscopy were investigated in 10 patients (8 males, 2 females) age 28-58 years) with end-stage renal failure treated by repeated hemodialysis. The examination was carried out twice: during a 4-hour hemodialysis session with the use of heparin alone and 1 week later during the course of another dialysis in the presence of both heparin and prostacyclin. During each dialysis session the platelet system was examined three times: prior to, after 90 min, and at the end of the procedure. As compared with the situation prior to dialysis, the number of platelet aggregates assessed after 90 min of dialysis and after its termination insignificantly rose following the treatment with heparin, but significantly fell after the use of the prostacyclin/heparin combination. The differences were also significant when the effects of both treatment types were compared. As revealed by scanning electron microscopy, during the course of hemodialysis with the use of heparin alone, the platelets showed signs of activation manifested by increases in number and length of cytoplasmic processes and by a tendency to aggregate. When both prostacyclin and heparin were used during dialysis, platelet activation was minimal or absent. Thus, the combined treatment with prostacyclin and heparin protects platelets from activation induced by their contact with artificial surfaces and may lower the risk of microthrombosis, making thereby hemodialysis safer and more effective.