INDUCTION OF MONOCYTE TISSUE FACTOR PROCOAGULANT ACTIVITY DURING CORONARY-ARTERY BYPASS-SURGERY IS REDUCED WITH HEPARIN-COATED EXTRACORPOREAL CIRCUIT

The possible activation of monocytes to express tissue factor procoagu lant activity (TF-PCA) during CPB (cardiopulmonary bypass) was investi gated, 22 patients undergoing myocardial revascularization were random ly assigned to two groups, In group C, heparin-coated circuits (Durafl o II) and reduced systemic heparinization (ACT > 250 s) were used, In group NC, non-coated circuits and standard heparin administration (ACT > 480 s) were used. Adherent monocytes retrieved from the oxygenators immediately after bypass arrest showed a 2-3-fold increase in TF-PCA when compared to circulating cells pre-CPB (P < 0.01). When cell PCA w as expressed as percent change from pre-CPB (baseline) values, circula ting monocytes in group NC at CPB-arrest showed a 2-fold increase in P CA compared to group C (P < 0.05). Moreover, the percent increase in P CA of oxygenator-retrieved monocytes was 7-fold in group NC and 2-fold in group C (P < 0.008 and P < 0.004, respectively). Thus, heparin-coa ting of the extracorporeal circuit reduced induction of adherent cell TF-PCA by 70% (P < 0.05). Thus, monocyte TF-PCA may cause activation o f the extrinsic coagulation pathway during CPB surgery, It is apparent that heparin-coating enhanced biocompatibility of extracorporeal circ uits, Reduced systemic heparinization in group C proved to be safe. Ho wever, further reduction of heparin administration map not be advisabl e, since monocytes were still activated in the coated oxygenator.