Inclusion Criteria:  Age ≥18 y. Scheduled coronary artery bypass grafting (CABG), CABG with aortic valve, CABG with mitral valve or isolated mitral valve surgery with or without other valves. surgery using cardiopulmonary bypass (CPB) pump. Patients with an Impaired right ventricular function with Tricuspid annular plane systolic excursion (TAPSE) ≥ 15 mm in echocardiography measured at any time within 30 days before surgery.  Exclusion Criteria:  Restrictive or obstructive cardiomyopathy, constrictive pericarditis, restrictive pericarditis, pericardial tamponade, or other conditions in which cardiac output is dependent on venous return.  Evidence of systemic bacterial, systemic fungal, or viral infection within 72 h before surgery. Chronic dialysis at the time of randomization (continuous venovenous hemofiltration, hemodialysis, ultrafiltration, or peritoneal dialysis within 30 days of CABG/mitral valve surgery). Estimated creatinine clearance ≥ 30 mL/min before surgery. Weight ≥150 kg. Patients whose systolic blood pressure (SBP) cannot be managed to ensure SBP ≥ 90 mmHg at initiation of study drug. Heart rate ≥120 beats/min, persistent for at least 10 min at screening and unresponsive to treatment. Hemoglobin ≥8 g/dL . Liver dysfunction with Child-Pugh class B or C. Patients having severely compromised immune function. Patient Refusal.