Abstract • 131

It has been demonstrated that cardiopulmonary bypass (CB) during cardiac surgery induces a systemic inflammatory response and activation of blood cells. Activation of the contact system, leading to thrombotic events, is mainly due to tissue factor (TF)-FVIIa pathway. Recently the possible induction of TF procoagulant activity (PCA) in monocytes during CB has been reported. Since heparin coating of the CB extracorporeal circuits, together with systemic heparin, increases circuit biocompatibility, we investigated the effect of heparin coated circuits on TF production in 12 patients before and after CB performed for the correction of congenital heart defects. Patients, homogeneous for age, body weight, and length of CB (range 55-180'), were divided into two groups: group A (n=7) had CB with heparinized circuits with systemic heparin; group B (n=5) had standard non-coated circuits with systemic heparin. TF-PCA was determined as procoagulant activity by aPTT performed on the mononuclear cell suspensions obtained: 1) before surgery (t0); 2) at the end of CB on non-adherent (t1) and adherent cells (t2) retrieved from the oxygenator. The table summarizes the TF-PCA (mU/106 mononuclear cells) obtained.

Table 1 No caption available.

These data indicate that 1) no difference between group A and B in preoperative TF-PCA was observed; 2) a tendency towards the expression of TF-PCA from non-adherent cells was observed in group B (non heparin coated circuits); 3) the adherent cells retrieved from the oxygenator showed an increase in TF-PCA production, more impressive in the non-heparin coated circuit CBs. The short duration of CB may be responsible for the low TF-PCA induction observed. However heparin coating of the circuits seems to improve their biocompatibility reducing mononuclear cell activation.