Objective:To evaluated the effects of sildenafil on hemodynamics and cardioprotection in rheumatic heart disease patients with pulmonary hypertension undergoing valvular heart surgery during cardiopulmonary bypass(CPB). Methods:After pulmonary arterial catheter insertion,patients with mean pulmonary arterial pressures(MPAP) greater than 30 mmHg were eventually included in this study. Twenty-eight cases were randomly divided into the control group(n = 14),and the experimental group(n = 14). Each patient in the experimental group was given 100 mg SIL(orally by nasal gastric tube) after induction of anesthesia. In control group,patients were placebo-controlled. Hemodynamic variables were measured after induction of anesthesia,at 0,20,40,and 60 minutes after medication. Blood samples were taken to determine the serum concentrations of CK-MB and cTn-T before cardiopulmonary bypass,at 2,6 and 16 h after aortic open-clamp. Results:Compared with the control group,the mPAP and mPAP/PmSAP was significantly reduced(P < 0.01) in the experimental group. And the levels of CK-MB at 2h after aortic open-clamp and cTn-T at 16 h after aortic open-clamp in the experimental group were significantly lower than those in control group(P < 0.05). Conclusion:Sildenafil produced significant pulmonary vasodilatory effect in cardiac surgical patients with pulmonary hypertension and beneficial effects such as myocardial protection.