Inhaled Versus Intravenous Milrinone for Patients Undergoing Mitral Valve Replacement Surgery

Patients will receive 2 doses of inhaled milrinone at the following time points (after sternotomy and after aortic cross clamp off) at dosage of 50 mcg/kg by nebulization, inhaled milrinone will be administered through Aerogen solo with Pro-X controller - continuous mode- attached to ventilator circuit distal to viral/ bacterial heat and moisture exchange filter.

Patients will receive intravenous milrinone infusion at dosage of 0.3 - 0.75 mcg/kg/min with loading dose of 50 mcg/kg over 10 min. After cross clamp off and temperature of 32 degree, Pulmonary vascular resistance and systemic vascular resistance will be calculated at the same corresponding time points to group A.