Abstract 19647: The Evolution of Cardiac Output and Cerebral Blood Flow in the Perinatal Transition in Hypoplastic Left Heart Syndrome: a Longitudinal Study
Background: Cardiovascular adaptation through the perinatal transition has not been previously explored in fetuses with hypoplastic left heart syndrome (HLHS). We sought to investigate the evolution of cardiac output in HLHS from late gestation through the perinatal period with comparison to healthy fetuses. As fetal HLHS has progressive middle cerebral arterial (MCA) Doppler changes suggestive of brain sparing, we further examined the impact of the transition on MCA blood flow. We hypothesized ductal patency with falling pulmonary vascular resistance after birth in HLHS could lead to cerebral steal.
Methods: We prospectively recruited 9 healthy and 11 pregnancies complicated by fetal HLHS. Echocardiograms were performed before birth at ≥37 weeks gestation and after birth at 4-6, 20-24, and 40-48 hours (all newborns), and 3-5 days (HLHS neonates only). Ventricular stroke volumes (SV) were determined using pulse Doppler and semilunar valve diameters, and combined cardiac output (CCO) was calculated (SV x heart rate (HR)). MCA pulsatility index (PI) was determined using the peak systolic, end diastolic and mean velocities.
Results: In late gestation, the CCO was similar between groups (HLHS mean 404 ± 91 vs. control 373 ± 96cc/kg/min). After birth, there was a trend towards higher CCO in HLHS at 4-6 and 20-24 hours (p= 0.06), which reached significance at 48 hours (587±155 vs controls 402±73 cc/kg/min, p=0.03). The CCO was highest in HLHS at 3-5 days (672 ± 117cc/kg/min, p<0.001 repeated measure ANOVA), due to higher HR and SV (for both versus controls, p<0.01). HLHS fetuses had significantly lower MCA PI than controls (1.2±0.1 vs 1.7±0.3, respectively, p<0.01); however, at 4-6 hours postnatally the MCA PI was higher in HLHS (1.8 ± 0.4 vs control 1.4±0.3, p= 0.04) and remained higher at 20-24 hours (p< 0.001) with higher systolic and lower end diastolic and mean velocities.
Conclusions: HLHS newborns significantly increase their cardiac output in the perinatal transition, particularly from 48 hours onward, through both increased HR and SV. While just prior to birth the MCA PI in HLHS suggests brain sparing, a reverse finding is observed after birth, which could reflect increased CCO and/or cerebral steal. This could be a period of cerebral vulnerability.
Author Disclosures: L. Mills: None. A. Hirose: None. S. Dhillon: None. E. Fortin-Pellerin: None. W. Savard: None. P. Cheung: None. D. Fruitman: None. N.S. Khoo: None. L.K. Hornberger: None.
- © 2014 by American Heart Association, Inc.