Heparin-coating of extracorporea circuits reduces thrombin formation in patients undergoing cardiopulmonary bypass

Abstract

This clinical study was performed to evaluate the inhibiting effects of heparin- coated extracorporeal circuits on thrombin formation during cardiopulmonary bypass (CPB). Thirty patients undergoing coronary artery bypass grafting were randomly divided into two groups with (Duraflo II, n=15) orwithout (control, n=15) the use of heparin-coated circuits. Standard systemic heparinization was performed in all the patients before CPB. The results showed that thrombin formation during the first phase of CPB was inhibited by heparin-coating identified by the significantly lower concentrations of thrombin-antithrombin III (TAT) complex formed in plasma in the Duraflo II group than in the control group (p <0.05). Heparin concentrations were higher in the Duraflo II group than in the control group at the end of CPB ( p <0.05). However, after release of the aortic crossclamp in the second phase of CPB, thrombin became strongly activated in both the Duraflo II and the control groups indicated by a sharp increase of TAT complex as well as fibrinopeptide A. Thus, Duraflo II heparin-coating reduces thrombin formation in the early phase of CPB, however, this beneficial effect was counteracted after aortic crossclamp release by material-independent stimuli. Therefore, adequate systemic heparinization is still required despite improved haemocompatibility of the circuits offered by heparin-coating.