Cardiopulmonary bypass with heparin-coated circuits and reduced systemic anticoagulation

The improved biocompatibility of the cardiopulmonary bypass circuits made possible by the use of surface-immobilized heparin may allow for a reduction in the amount of heparin administered systemically. This study was performed to elucidate the effects of cardiopulmonary bypass using heparin-coated circuits and reduced heparinization on hemostatic variables and clinical outcome.

Thirty patients scheduled to undergo myocardial revascularization were randomized to have either a heparin-coated or an uncoated cardiopulmonary bypass circuit. Anticoagulation was induced with heparin (100 IU/kg in the coated group and 300 IU/kg in the uncoated group) and the activated clotting time was kept over 200 and 480 seconds in the coated and uncoated groups, respectively.

The postoperative overnight loss of hemoglobin through the drains was lower in the heparin-coated group (43.6 g; range, 18.5-69.0 g) than in the uncoated group (73.0 g; range, 32.2-137.7 g) (p = 0.0015). Plasma concentrations of prothrombin fragment 1 + 2 and D-dimer were significantly more elevated after cardiopulmonary bypass in the coated group than they were in the uncoated group. Two patients in the coated group had a stroke postoperatively.

The reduction in systemic heparinization was associated with thrombin formation, which may predispose to intravascular and cardiopulmonary bypass circuit clotting. Therefore, generous systemic heparinization may still be prudent despite the improved biocompatibility offered by heparin-coated surface.