This clinical study was performed to evaluate the inhibiting effects of heparincoated 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.

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