Suppressed fibrinolysis after administration of low-dose aprotinin: reduced level of plasmin-alpha2-plasmin inhibitor complexes and postoperative blood loss.

Various clinical investigation have shown that aprotinin therapy reduces bleeding after open-heart operations. In this study low-dose aprotinin, 30,000 KIU/kg in the cardiopulmonary bypass (CPB) priming volume and 7,500 KIU/kg intravenously each hour during CPB, was used in ten patients undergoing primary myocardial revascularization or surgery for valvular diseases. Another ten patients served as controls. Blood loss, platelet count and plasma levels of hemoglobin, antithrombin III, fibrinogen, fibrinogen degradation products (FDP), total plasmin inhibitor and alpha2-plasmin inhibitor-plasmin complexes were evaluated at nine preoperative, intraoperative and postoperative points. Intraoperative and postoperative blood loss was significantly reduced in the aprotinin group. There was no significant difference between the two groups in platelet count and levels of hemoglobin and antithrombin III. A significant increase in FDP during CPB in the control group indicated hyperfibrinolysis. The levels of plasmin inhibitor were significantly reduced during CPB in the control group. The alpha 2-plasmin inhibitor-plasma complex levels, indicating the plasmin activity, were significantly reduced in the aprotinin group. These results confirmed that low-dose aprotinin reduced blood loss with the prevention of hyperfibrinolysis during CPB and demonstrated improved hemostasis.