Complete heparin-coated cardiopulmonary bypass and low heparin dose reduce complement and granulocyte activation

Complete heparin-coated extracorporeal circuits, including cardiotomy reservoir, have recently become available for routine cardiac surgery. The effects on complement and granulocyte activation using a heparin-coated circuit in combination with reduced systemic heparinization (activated clotting time (ACT) > 250 s) were studied in 33 patients undergoing elective first time myocardial revascularization. The patients were prospectively randomized either to a heparin-coated group (Group H, n = 17), or to a control group (Group C, n = 16) treated with an identical uncoated circuit and full heparin dose (ACT > 480 s). During cardiopulmonary bypass (CPB) the C3 activation products C3b, iC3b, and C3c (C3bc) and the terminal SC5b-9 complement complex (TCC) increased markedly in both groups compared to baseline, but to a much lesser extent in the heparin-coated group. The maximal increase of C3bc during the operation was a median of 28 arbitrary units (AU)/ml in the heparin-coated group, compared to 45 AU/ml in the control group (P = 0.01). Similarly, in Group H the maximal increase of TCC was significantly lower (median 0.8 AU/ml) than the levels recognized in Group C (median 1.9 AU/ml) (P < 0.0001). The release of the granulocyte activation enzymes lactoferrin and myeloperoxidase also increased during CPB in both groups compared to baseline level. The maximal increase of lactoferrin concentration was a median of 229 micrograms/l in Group H and significantly lower than 647 micrograms/l in the control group (P = 0.0002). As for myeloperoxidase, there were no significant intergroup differences. In conclusion, a complete heparin-coated circuit and low systemic heparinization for CPB in coronary artery surgery were associated with reduced activation of the complement system and less release of lactoferrin. The results indicate improved biocompatibility of this option for extracorporeal circulation.