Monitoring of anticoagulation in aprotinin-treated patients during heart operation.

Since aprotinin has become extensively used during cardiopulmonary bypass the maintenance of safe anticoagulation is a concern. Aprotinin affects anticoagulation measurement by the activated clotting time. Therefore, a reliable new measurement is needed to monitor anticoagulation during cardiopulmonary bypass. In the present study, we tested the efficacy of two alternative measurements in which whole blood clotting was stimulated by high-dose thromboplastin or by high-dose thrombin. During cardiopulmonary bypass under standardized heparinization, the activated clotting time was twofold longer in the aprotinin group than in control group (p < 0.05), whereas high-dose thromboplastin and high-dose thrombin groups were not significantly affected by aprotinin. In laboratory tests using blood from healthy volunteers, all methods showed linear correlation with heparin concentration in the absence of aprotinin (p < 0.05). However, the activated clotting time measurement was prolonged more by heparin when aprotinin was present (p < 0.05), whereas high-dose thromboplastin and high-dose thrombin measurements were not. Moreover, these measurements were faster and more dependable than the activated clotting time. Therefore, high-dose thromboplastin time and high-dose thrombin time seem to be reliable for monitoring anticoagulation when aprotinin is used during cardiopulmonary bypass.