Heparin-coated extracorporeal circulation with full and low dose heparinization: comparison of thrombin related...

Thrombin related coagulatory effects of a heparin-coated cardiopulmonary bypass system combined with full and low dose systemic heparinization were investigated in a prospective, randomized study in coronary bypass surgery patients. One hundred nineteen patients were divided into 3 groups. Group A (n = 39) had a standard uncoated extracorporeal circulation (ECC) set, and systemic heparin was administered in an initial dose of 400 IU/kg body weight. During ECC activated clotting time (ACT) was maintained at > or =480 s. Group B (n = 42) had the same ECC set completely coated with low molecular weight heparin. Intravenous heparin was given in the same dose as in Group A, and ACT was kept at the same level. Group C (n = 38) had the same coated ECC set as Group B, but intravenous heparin was reduced to 150 IU/kg, and during ECC, ACT was set to be > or =240 s. The same ECC components were used in all 3 groups including roller pumps, coronary suction, and an open cardiotomy reservoir. Thrombin generation as indicated by F1/F2 was significantly elevated at an ECC duration >60 min if heparin-coated ECC combined with low dose systemic heparinization was employed. Complexed thrombin (TAT) was significantly elevated after administration of protamine. Release of D-dimers indicating fibrinolysis was not significantly different between groups. Signs of clinical thromboembolism, i.e., postoperative neurological deficit, occurred in 2 patients in Group A and 1 patient in Group C. We conclude that heparin-coated extracorporeal circulation combined with reduced systemic heparinization intraoperatively leads to significantly increased thrombin generation, but not to increased fibrinolysis.