Is reduced systemic heparinization justified with heparin-bonded bypass circuits in cardiac surgery?--Experience with and without aprotinin

Abstract

The effects of aprotinin combined with heparin-bonded bypass circuits and reduced systemic heparinization on haemostasis and inflammatory reactions were measured in patients with elective CABG operation. Patients were randomized to be operated on either without aprotinin (NOAPRO, n=15) or with aprotinin (APRO, n=15) at a low dose of 2 Mio KIU in the priming volume. Activated clotting time was adjusted to 400 +/- 50 s during cardiopulmonary bypass (CPB). Haemostasis (fibrinopeptide A (FPA), thrombin-antithrombin complex (TAT), D-Dimer, plasmin-antiplasmin (PAP), plasminogen-activator inhibitor (PAI)), inflammatory reaction (lactoferrin, IL-6, sTNF-IIR, SC5b-9) and clinical data were evaluated perioperatively. Perioperative clinical and laboratory data including mediastinal drainage volume, postoperative morbidity and mortality were comparable for patients in both groups. FPA was elevated in the APRO group during CPB (P=0.001), D-Dimer in the NOAPRO group after CPB (P=0.002). No differences were seen for TAT, PAP or PAI between the groups. Lactoferrin was elevated in NOAPRO at the end of CPB (P=0.01) and after heparin reversal with protamine sulphate (P=0.02). No intergroup differences were seen for IL-6, sTNF-IIR or SC5b-9 between the groups. In association with reduced heparinization, pump prime aprotinin retains its antifibrinolytic effect in modified bypass equipment with a heparin surface besides an anti-inflammatory effect in terms of inhibition of leukocyte activation. However, thrombin activation may be increased with aprotinin. We therefore recommend sufficient systemic heparinization despite heparin surface modification of bypass equipment.