APROTININ EFFECT ON PLATELET-FUNCTION AND CLOTTING DURING CARDIOPULMONARY BYPASS

A variety of studies have been performed on the preservation of hemost asis by aprotinin during cardiopulmonary bypass (CPB). It appears that the mechanism of aprotinin to preserve hemostasis can be interpreted in different ways. Our previous studies suggested that preservation of platelet glycoprotein lb (GpIb) antigen, and counteraction of heparin anticoagulation in the extrinsic clotting pathway might partly explai n the preservative effect of aprotinin. A clinical study was therefore conducted to evaluate these effects during the use of low dose aproti nin. Improved agglutination by ristocetin (P < 0.05), and improved GpI b antigen expression (P < 0.05) during CPB showed better preserved pla telet adhesive capacity in the aprotinin group than in the control gro up. Glycoprotein lb antigen expression and the agglutination capacity with ristocetin during CPB were closely related (P < 0.05). Platelet G pIIb/IIIa antigen and adenosine diphosphate (ADP) aggregation were not significantly different between the aprotinin and control groups. Apr otinin had no effect on the extrinsic clotting pathway in the blood, s ince the thromboplastin clotting time was similar in both groups. Thes e results indicate that the protection of platelet adhesive capacity d uring CPB is a main function of aprotinin, whereas no evidence was col lected for enhanced extrinsic clotting by aprotinin during CPB.