Objective:To investigate the protective effect of shenfu injection on myocardium in patients undergoing open cardiac surgery with cardiopulmonary bypass (CPB).Methods:Sixty patients scheduled for selective cardiac surgery were randomly divided into Shenfu group and control group with 30 cases respectively.In Shenfu group,2ml/kg Shenfu injection was added into membrane oxygenator before CPB.Blood samples were collected to measure the concentration of serum AST,CK,CK-MB,LDH before operation,30rain after cross-clamp of ascending aorta and 10rain after release of cross-clamp.The levers of serum cTnI and MDA in myocardium were measured 30min after cross-clamp of ascending aorta and 10min after release of cross-clamp.