Surgery and CPB regimen All surgery is performed by one surgeon and 4 surgical assistants. After performing sternotomy and administration of heparin 300 units/kg, arterial and venous cannulations for CPB are performed at activated clotting time (ACT) > 450 sec and CPB was conducted using reservoir, membrane oxygenator, roller pump and heat exchanger. Priming volume for CPB was composed of normal saline, 20% mannitol, NaHCO3, 20% albumin, heparin, antibiotics and calcium gluconate. The flow of CPB is initiated at 60 ml/kg/min and adjusted by the current hemodilution and temperature.