Abstract 16846: Hemodynamic Effects of alpha-Adrenergic Blockade With Phentolamine Following Stage One Palliation of Hypoplastic Left Heart Syndrome
Background: We used phenoxybenzamine (PBZ) with an FDA-approved IND to reduce systemic afterload and improve systemic oxygenation in patients with hypoplastic left heart syndrome (HLHS) after stage 1 palliation (S1P) with unsurpassed operative,1-year and 5-year outcomes. With parenteral PBZ no longer available, we initiated a protocol for intraoperative phentolamine (PHT) bolus and titrated postoperative infusion in an attempt to reproduce the hemodynamics previously achieved with PBZ. The primary aim of this study was to characterize the comparative global and regional hemodynamic effects of PHT in neonates following S1P for HLHS.
Methods: PBZ was administered as a single dose of 200 mcg/kg at initiation of CPB. PHT was administered as a 250 mcg/kg bolus at initiation of CPB followed by 0-2 mcg/kg/min infusion. Hourly hemodynamic and laboratory data for the first 48 postoperative hours were extracted and analyzed for this report with IRB approval.
Results: Data from 31 consecutive patients receiving PHT and the previous 31 consecutive PBZ patients were analyzed. Patient demographics and surgical variables (age and weight at S1P, ascending aortic diameter, gender, shunt size and type, CPB time) were not different. Survival to discharge 29/31 (94%) in both groups. ECMO support was used in 1/31 (3%) PHT vs 4/31 (14%) PBZ patients (p=0.15). The PHT group had similar SaO2, SvO2, arterial pressure, central venous pressure, but lower heart rate (165±17 vs 170±14, p<0.005) and higher cerebral (65±10 vs 63±9, p<0.05) and renal/somatic (78±10 vs 74±11, p<0.005) saturation by NIRS. Absolute base excess and rate of change were not different between groups. Of the 31 patients in the PHT group, 21 (68%) received postoperative PHT at an initial infusion rate of 1.16±0.37 mcg/kg/min; 20 (65%) were still receiving PHT infusion at >0.5 mcg/kg/min at 12 hours postop, with higher base excess at all SvO2, and higher SvO2 at the extremes of SaO2 and BP. Optimal regional and global hemodynamics were observed at infusion rates of 0.5-1.0 mcg/kg/min. Summary: PHT infusion can mimic the global and regional hemodynamic effects of phenoxybenzamine, and achieve targeted cerebral, renal, and venous oxygen saturations with less metabolic acidosis.
- Hypoplastic left heart
- Autonomic nervous system
- Alpha-adrenergic receptor blockers
- Regional circulation
- © 2013 by American Heart Association, Inc.