40 patients will be randomly assigned to either the traditional heparin management group or the intervention group. The traditional group will be treated with an initial heparin dose of 400 units/kg and the standard amount of heparin, as dictated by the circuit size, will be added to the CPB circuit prime. An ACT target value of 480 seconds will be maintained throughout the bypass period. Should the ACT fall below 480 seconds,additional boluses of 100 units/kg of heparin will be given until the ACT returns to the target value. At the end of CPB, heparin will be neutralized by the standard reversal of 4 mg/kg of protamine.