Combined effect of milrinone and NO to treat pulmonary hypertension after cardiopulmonary bypass in congenital heart disease patients

Objective To investigate the effect of milrinone combined with nitric oxide (NO) on pulmonary artery pressure after cardiopulmonary bypass (CPB) in congenital heart disease (CHD) complicated by pulmonary hypertension (PH). Methods Twenty-four ASA II/III patients with CHD and PH (NYHA grade II or III) undergoing open heart surgery under CPB were randomly divided into three groups (n=8 each): group N (inhaled NO, n=8), group M (milrinone group, n=8) and group NM (combined group, n=8), In group M, the patients after removal of aortic clamp received a loading dose of 50 mu g/kg milrinone followed by a continuous infusion at 0.5 mu g/kg/min till the end of operation. In group N, the patients inhaled 20ppm NO for 45 min after successfully weaning from CPB. In group NM, as the aortic clamp was removed, a bolus of 50 mu g/kg milrinone was given which was followed by continuous infusion at 0.5 mu g/kg/min till the end of surgery, and after successful weaning from CPB, patients were given inhaled 20ppm NO for 30mins. Mean pulmonary artery pressures (mPAP), mean systemic pressure (MAP) and cardic index (CI), pulmonary vascular resistance index (PVRI), systemic vascular resistance index (SVRI) values were recorded before operation (TO, baseline), after weaning from CPB (T1), at inhaled NO for 15mins (T2) and 30 minutes (T3), and 15mins (T4) after the termination of NO inhalation. Results The 3 groups were comparable with respect to age, body weight, body surface area and CPB time. In NO group, NO inhalation significantly decreased mPAP(22 +/- 16)% and PVR by (32 +/- 24)% compared with baseline values at TO (p<0.05), but they slightly rebounded after termination of NO inhalation at T4. In group M, milrinone significantly decreased PVRI by (30 +/- 12) % compared to baseline values (p<0.05) but did not significantly change mPAP. In group NM, milrinone and NO significantly decreased mPAP by (26 +/- 4)% and PVRI (31 +/- 13)% (p<0.05) and they did not rebound after termination of NO inhalation. Conclusion Milrinone infusion combined with NO inhalation can significantly reduce mPAP and PVR after CPB in patients with CHD and PH. Milrinone can prevent rebound PH after termination of NO inhalation.