319 The Effect of Milrinone Infusion on Cerebral Perfusion in Neonates with Congenital Heart Disease Prior to Cardiac Surgery

Background Milrinone has been increasingly used in the post-operative care of neonates with congenital heart disease (CHD) for its inotropic and vasodilatation properties. When used as a pre-operative cardiovascular supportive agent, cerebral hemodynamic effects of milrinone have not been studied. Methods From June 2008 to July 2010, 18 neonates with CHD and treated with milrinone before cardiac surgery were prospectively enrolled. Milrinone (0.75mcg/kg/min) was given according to institutional guidelines and neonates (n=1) requiring additional vasoactive agents were excluded. Using Doppler studies, cardiac output (CO), flow velocity (Vm) and Resistive Index (RI) for anterior and middle cerebral arteries were assessed and analyzed blindly at specific time-points after milrinone administration. Results Seventeen neonates were studied (gestation: 39.5[36–41]weeks; birth-weight: 3350[2590–4230]g). Hypoplastic left heart syndrome was the most common CHD. Milrinone was commenced at day 1–7 (88% on day 1) of life, with heart rate 141±[SD]14bpm, mean blood pressure 44±6mmHg and CO 479±147ml/min/kg at baseline. At 6h, 24h and 48h, CO was significantly increased by 23%, 20% and 28% from pre-treatment baseline, respectively, with increased anterior (22%, 35%, 38%) and middle (34%, 36%, 35%) cerebral Vm. There were no significant changes in heart rate (150–160bpm), mean blood pressure (43–46mmHg) and RI during infusion. Plasma lactate concentrations decreased and urine output improved over 48h. One patient developed stroke pre-treatment; another had persistent hypotension after milrinone. Sixteen (94%) neonates survived to hospital discharge. Conclusions Milrinone improves CO and cerebral blood Vm without significant effects on blood pressure and RI. (Funded by Stollery Children’s Hospital Foundation).