Cardiopulmonary bypass (CPB) is a critical technology in cardiac surgery, allowing for the temporary replacement of the heart and lung functions during intricate surgical procedures. it has significant post-surgical complications, the most important complications of CPB is right ventricle (RV) dysfunction. Diagnosis and management of RV dysfunction is crucial for maintenance of hemodynamic stability and organ function in early post-operation period and prognostic for later phase.

Epinephrine is the most potent adrenergic agonist which has positive inotropic and chronotropic effects and enhanced conduction in the heart (β1), smooth muscle relaxation in the vasculature and bronchial tree (β2), and vasoconstriction (α1). Low doses of this agent (<0.1-0.2 μg/kg/min) mainly activate the β adrenoceptors with inotropic effects. Higher doses result in vasoconstrictor effect which takes the lead. Other effects include bronchial dilation, mydriasis, glycogenolysis, tachyarrhythmia, myocardial ischemia, pulmonary hypertension, hyperglycemia, and lactic acidosis. Epinephrine also reduces splanchnic and hepatic perfusion and increases metabolic workload of the liver. So this hypermetabolism that impairs oxygen exchange, glycolysis, and suppression of insulin cause lactic acidosis.

Milrinone is a phosphodiesterase-III inhibitor. This effect decreases the degradation of cyclic adenosine monophosphate (cAMP), increases the cAMP levels in cells, and then increases activation of protein kinase A. Therefore, its cardiac effects are positive inotropy and improved diastolic relaxation. Milrinone also causes potent vasodilation, with reduction in preload, afterload and pulmonary vascular resistance. Considering its characteristics, milrinone might be a useful agent for cardiac surgery patients.

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status II & III
• Age between 18 and 70 years
• Both Gender
• Body mass index less than 40 kg/m2
• Ejection fraction of >40%
• Tricuspid annular plane systolic excursion (TAPSE) < 1.7cm

Exclusion Criteria:

• Patient refusal.
• Preoperative RV impairment
• Pulmonary hypertension (estimated pulmonary artery systolic pressure > 50 mmHg)
• Patients with any contraindications to Transesophageal echocardiography (TEE)
• Redo or Re-exploration surgery
• Patients with chronic kidney disease (serum creatinine > 1.5 mg/ dl)
• Patients with chronic liver disease (child pugh B and C)

anesthesiologist who performed TEE measurements and who was responsible for data collection will be blinded to patient group allocation