Objective To study the protective effects and possible mechanism of Shengmai Injection on myocardium of patients with heart valve replacement under general anesthesia with propofol. Methods Forty patients with heart valve replacement were randomly divided into the observation group and the control group

with 20 cases in each group. The observation group was given intravenous injection with Shengmai Injection（ 1 ml / kg） before anesthesia with propofol. At the same time

the control group was given intravenous injection with the same volume of normal saline. The mean arterial pressure

heart rate

central venous pressure

blood oxygen saturation in two groups were compared

and the levels of malondialdehyde

superoxide dismutase

and nitric oxide synthase in venous blood were tested before entering the operating room

before and after cardiopulmonary bypass

and at the end of the operation.Results Before and after cardiopulmonary bypass and at the end of the operation

the mean arterial pressure was significantly higher in the observation group than that in the control group（ P < 0. 05）; At the end of the operation

heart rate in the observation group was significantly higher than that in the control group（ P < 0. 05）; Before and after cardiopulmonary bypass

levels of malondialdehyde and nitric oxide synthase were lower

but level of superoxide dismutase was higher in the observation group than those in the control group（ P < 0. 05）. Conclusion Shengmai Injection can protect myocardium of patients with heart valve replacement under general anesthesia with propofol. Its possible mechanism is due to increasing myocardial antioxidant and reducing oxide.