Inhaled and Intravenous Milrinone in Patients With Severe Pulmonary Hypertension

This study compares inhaled milrinone (breathed in as a mist) versus intravenous milrinone (given through a vein) to treat severe pulmonary hypertension — dangerously high blood pressure in the lungs — in patients undergoing mitral valve surgery with a heart-lung bypass machine. **You may be eligible if...** - You are scheduled for mitral valve surgery using cardiopulmonary bypass (heart-lung machine) - Your pre-operative echocardiogram shows an estimated mean pulmonary artery pressure of 55 mmHg or higher (severely elevated lung blood pressure) **You may NOT be eligible if...** - Your surgery does not use a heart-lung bypass machine - You have severe left ventricular dysfunction (very poor heart pumping) - You have congenital heart disease, severe kidney or liver disease, or a blood clotting disorder - You are having emergency or repeat (redo) surgery Talk to your doctor to see if this trial is right for you.