COMPLETELY HEPARINIZED CARDIOPULMONARY BYPASS AND REDUCED SYSTEMIC HEPARIN - CLINICAL AND HEMOSTATIC EFFECTS

Background. When heparinized circuits are used for cardiopulmonary byp ass, the amounts of heparin and protamine administered systemically ca n be reduced. However, it is not entirely known what effects this redu ction in systemic anticoagulation has on clinical performance and on t he coagulation and fibrinolytic systems. Methods. Two hundred three pa tients undergoing first-time elective myocardial revascularization wer e prospectively randomized either to a group in which a completely hep arin-coated circuit was used for perfusion (group H; n = 101 patients) and in which a reduced heparin dose was given (activated clotting tim e, >250 seconds) or to a control group (group C; n = 102 patients) in which an uncoated, but otherwise identical, circuit was used and in wh ich full systemic heparinization was induced (activated clotting time, >480 seconds). Indicators of thrombin generation, platelet activation , and fibrinolytic activity were studied in a subset of 34 patients. R esults. The total amount of postoperative mediastinal drainage was sig nificantly reduced in group H (median, 575 mL) compared with that in g roup C (median, 635 mL; p = 0.002). Two patients in group C but none i n group H received homologous red blood cell transfusions (p = not sig nificant). The loss of hemoglobin in group H was a median of 21 g/L, a nd this was significantly lower than the 25 g/L noted in the control g roup (p = 0.006). During cardiopulmonary bypass, the plasma levels of thrombin-antithrombin complex and prothrombin fragment 1.2 increased i n both groups. At the end of cardiopulmonary bypass the plasma levels of these markers of thrombin formation were significantly higher in gr oup H, although the increase was modest compared with the major increa se observed 2 hours after operation in both groups. There were no sign ificant intergroup differences in the platelet counts, the concentrati on of beta-thromboglobulin, or the plasma levels of fibrinogen and D-d imer. No differences in perioperative morbidity, the postoperative kid ney function, or the intubation time were observed, and there were no hospital deaths. Conclusions. The combination of complete heparin-coat ed cardiopulmonary bypass circuits and low systemic heparinization is safe for patients undergoing elective coronary artery bypass procedure s and reduces the perioperative blood loss. There was no evidence of i ncreased thrombogenicity, fibrinolytic activity, or consumption of coa gulation factors. No clinical or technical side effects were observed.