30 Patients were randomly allocated in two equal groups; group MS (received intravenous milrinone and oral sildenafil) and group M (received only intravenous milrinone). Demographic data, patient's clinical data and different intraoperative times were recorded. In 1st postoperative 24 hours, we recorded; hemodynamic parameters [mean pulmonary arterial pressure (MPAP), mean systemic arterial pressure (MAP), heart rate, central venous pressure]. We calculated MPAP/MAP and inotropic score. The incidence of pulmonary hypertensive crisis, side effects of studied drugs and complications related to pulmonary artery catheter were recorded.