Blood Platelets and Extracorporeal Circulation*

Abstract

Platelet adhesiveness has been studied in patients undergoing cardiopulmonary bypass. Conventional doses of heparin do not alter platelet adhesiveness. With the onset of perfusion, however, there is a precipitous fall in platelet count and in the adhesiveness of those platelets remaining. It appears that a circulating inhibitor of platelet sticking is present during perfusion. In most cases, this defect gradually disappears after perfusion. In a few patients with excessive bleeding, persistent abnormalities in platelet adhesiveness have been demonstrated.