Additive Effect of Phosphodiesterase Inhibitors in Control of Pulmonary Hypertension after Congenital Cardiac Surgery in Children

Objective: Control of residual pulmonary arterial hypertension (PAH) after closure of left to right shunts in children is still a challenging issue. The purpose of this study was to compare the effect of two phosphodiesterase inhibitors in pediatric cardiac surgical patients.
Methods: A total of 48 postoperative children were enrolled in the study between 2008 and 2010. Patients were stratified based upon choice of pulmonary vasodilator into three equal groups (n=16); Milrinone group received intravenous milrinone (0.75 μ/kg/min), Sildenafil group received oral sildenafil (0.3 mg/kg every 3 hours) and the Combination group received both medications.
Findings: Demographic variables and types of congenital anomalies were not different among the 3 groups. Patients in the Combination group had higher preoperative pulmonary artery to aortic (PA/AO) pressure ratios compared to other two groups (P=0.001). Postoperatively, patients in Milrinone group incurred lower systolic PA and PA/AO pressures compared to Sildenafil group (P=0.014, 0.003), but it was the same in Sildenafil and Combination group (P=0.2; 0.330 respectively). Pulmonary hypertensive crisis was noted in 6 patients in Sildenafil group, and 3 patients in Combination group (P=0.02). Significant rise in PA pressure was noticed after discontinuation of drug in Milrinone group (P=0.001), which was not observed in the Combination group (P= 0.6). No mortality was noticed in any of the groups.
Conclusion: Intravenous milrinone is more effective than oral sildenafil in control of postoperative PAH and elimination of pulmonary hypertensive crisis. Combination of two drugs reduces the risk of rebound pulmonary arterial hypertension after discontinuation of milrinone.

Keywords
Phosphodiesterase Inhibitors; Pulmonary arterial hypertension; Cardiac surgery; Children