Inhaled versus intravenous milrinone in mitral stenosis with pulmonary hypertension

To evaluate and compare the hemodynamic effects of intraoperative intravenous milrinone versus inhalational milrinone at two timepoints in patients with severe pulmonary hypertension undergoing mitral valve surgery.

A prospective observational study was performed in 100 patients with severe rheumatic mitral stenosis (with/without regurgitation) and right ventricular systolic pressure > 50 mm Hg. They were divided into two groups based on the strategy used to reduce pulmonary hypertension. Fifty patients had inhalational milrinone after sternotomy until initiation of cardiopulmonary bypass and after release of the aortic crossclamp until weaning off cardiopulmonary bypass. The other 50 patients received an intravenous loading dose of milrinone 50 µg·kg^-1 over 10 min on release of the aortic crossclamp. Both groups received intravenous milrinone 0.5 µg·kg^-1 during weaning from cardiopulmonary bypass. Hemodynamic data were evaluated at the 3 timepoints.

Pulmonary artery pressures, central venous pressure, and pulmonary capillary wedge pressure decreased significantly in the inhalational milrinone group compared to the intravenous milrinone group. Systemic vascular resistance index and cardiac index were significantly higher and pulmonary vascular resistance index was significantly lower in the inhalational milrinone group. The mean arterial pressure-to-mean pulmonary artery pressure ratio was significantly lower in the intravenous milrinone group. Tricuspid annular plane systolic excursion and right ventricular fractional area change were increased significantly in the inhalational milrinone group.

Intraoperative inhalational milrinone before and after cardiopulmonary bypass is safe, easy to administer, and results in significant improvements in right ventricular hemodynamics, right ventricular function, and systemic hemodynamics.