A retrospective comparison of aerosolized milrinone and aerosolized iloprost in the setting of post bypass pulmonary hypertension

Background & Aim. Right ventricular failure (RVF) secondary to pulmonary regurgitation (PR) impairs right ventricular (RV) function and interrupts the interventricular relationship. There are few recommendations for the medical management of severe RVF after prolonged PR. Methods. PR was induced in 16 Danish landrace pigs by plication of the pulmonary valve leaflets. Twenty-three pigs served as controls. At re-examination the effect of milrinone, epinephrine and dopamine was evaluated using biventricular conductance and pulmonary catheters. Results. Eighty-one days after PR was induced, RV enddiastolic volume index (EDVI) had increased by 33% (p1⁄40.006) and a severe decrease in the load-independent measurement of contractility (PRSW) (-58%; p1⁄40.003). Lower cardiac index (CI) (-28%; po0.0001), mean arterial pressure (-15%; p1⁄40.01) and mixed venous oxygen saturation (SvO2) (36%; po0.0001) were observed compared to the control group. The interventricular septum deviated towards the left ventricle (LV). Milrinone improved RV-PRSW and CI and maintained systemic pressure while reducing CVP. Epinephrine and dopamine further improved biventricular PRSW and CI equally in a dose-dependent manner. Systemic and pulmonary pressures were higher in the dopamine-treated animals compared to epinephrine-treated animals. None of the treatments improved stroke volume index (SVI) despite increases in contractility. Strong correlation was detected between SVI and LV-EDVI, but not SVI and biventricular contractility. Conclusion. In RVF due to PR, milrinone significantly improved CI, SvO2 and CVP and increased contractility in the RV. Epinephrine and dopamine had equal inotropic, but a greater vasopressor effect was observed for dopamine. SV was unchanged due to inability of both treatments to increase LVEDVI.