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 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.

Thrombin generation during cardiopulmonary bypass: the possible role of retransfusion of blood aspirated from the surgical field

“…Despite these improvements, however, we and also other investigators reported no reduction in thrombin generation in patients undergoing CPB with the use of a heparin-coated extracorporeal circuit [14-17], whereas others have found evidence of some possible benefit of these surfaces on the coagulation cascade [18]. …”

Effective Use of Heparin-Bonded Circuits and Lower Anticoagulation for Coronary Artery Bypass Grafting in Jehovah's Witnesses

“…Based on current experimental and clinical data, we believe that HBCs with lower levels of anticoagulation are more thromboresistant than conventional (nonheparin bonded) circuit with full anticoagulation. [17][18][19][20] As with all modifications, the techniques of CPB have to be adjusted to ensure patient safety and the limitations of these techniques have to be clearly understood.13 These limitations are not unique to HBCs, but are shared by all extracorporeal circulation modalities, although concerns are accentuated in the presence of lower anticoagulation. These concerns include identification with patients with hypercoagulable states or antithrombin Ill deficiencies, intraoperative administration of any drugs which shift the hemostatic balance and promote thrombosis, and avoidance of blood turbulence and stagnation.…”

Heparin-bonded circuits: clinical outcomes and costs

“…17 The blood-surface interface changes when heparinbonded circuits are used during CPB, resulting in reduced activation of neutrophils, platelets, and complement. [18][19][20][21][22][23][24] Heparin can be bonded either ionically or covalently to plastic surfaces due to its strong acidity.…”

“…The most significant difference resulting from the two types of bonds appears to be that the weaker ionic bonds result in leaching and higher post-CPB heparin levels. 20,25 …”