Heparin-coated extracorporeal circulation with full and low dose heparinization: Comparison of thrombin related coagulatory effects

Thrombin related coagulatory effects of a heparin-coated cardiopulmonary by pass system combined with full and low dose systemic heparinization were in vestigated in a prospective, randomized study in coronary bypass surgery pa tients. One hundred nineteen patients were divided into 3 groups. Group A ( n = 39) had a standard uncoated extracorporeal circulation (ECC) set, and s ystemic heparin was administered in an initial dose of 400 IU/kg body weigh t. During ECC activated clotting time (ACT) was maintained at greater than or equal to 480 s. Group B (n = 42) had the same ECC set completely coated with low molecular weight heparin. Intravenous heparin was given in the sam e 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 greater than or equal to 2 40 s. The same ECC components were used in all 3 groups including roller pu mps, coronary suction, and an open cardiotomy reservoir. Thrombin generatio n as indicated by F1/F2 was significantly elevated at an ECC duration > 60 min if heparin-coated ECC combined with low dose systemic heparinization wa s employed. Complexed thrombin (TAT) was significantly elevated after admin istration 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.