EFFECTS ON COAGULATION AND FIBRINOLYSIS WITH REDUCED VERSUS FULL SYSTEMIC HEPARINIZATION AND HEPARIN-COATED CARDIOPULMONARY BYPASS

Background Extracorporeal circulation with circuits coated with surfac e-bound heparin has allowed reduced levels of systemic heparinization. Clinical benefits have included reduced postoperative bleeding and le ss homologous blood usage. However, the effects on the hemostatic and fibrinolytic systems have remained in part unknown. Methods and Result s Indications of thrombin generation, platelet activation, and fibrino lytic activity were investigated in patients undergoing coronary arter y bypass surgery. Two groups were perfused with cardiopulmonary bypass (CPB) circuits completely coated with surface-bound heparin: one grou p with low systemic heparin dose (activated clotting time [ACT] >250 s econds; n=17) and a second group having a full heparin dose (ACT >480 seconds; n=18). A third control group was perfused with ordinary uncoa ted circuits and full heparin dose (n=17). The plasma level of thrombi n-antithrombin complex and prothrombin fragment 1.2 increased in all g roups during bypass, and somewhat more in both the heparin-coated grou ps toward the end of CPB, compared with the control group (P<.01). How ever, the increase during CPB was minimal compared with the major elev ation observed 2 hours after surgery in all groups. Platelet release o f beta-thromboglobulin increased in all groups (P<.01) during CPB and significantly more in the high-dose group compared with the other two groups (P=.03). Fibrinolytic activities were similar in all groups, an d there were no indications of major consumption of coagulation factor s. Conclusions Reduced systemic heparinization (ACT >250 seconds) in p atients having extracorporeal circulation with completely heparin-coat ed circuits did not lead to increased thrombogenicity. Thrombin format ion remained within low ranges during CPB compared with patients recei ving a full heparin dose and with the major elevations observed after surgery.