Autonomic Nervous System Function in Newborns with Congenital Heart Disease

Abstract

Infants with complex congenital heart disease (CCHD) exhibit abnormal autonomic nervous system (ANS) function prenatally and are exposed to stressful environments postnatally that further alters autonomic development. Impaired autonomic function during early infancy influences behavioral, social, and cognitive development, and infants with CCHD are at high risk for developmental delays. The purpose of this study is to describe autonomic function during the perioperative period in newborns with CCHD and to explore associations with type of cardiac defect. In this multiple case study design, linear (power spectral density) and non-linear (Poincare plots) heart rate variability (HRV) were examined using four to 20 hour electrocardiographic recordings collected on four newborn infants with different types of CCHD. Data were collected during hospitalization once before surgery and once five to seven days after surgery. Hourly HRV was examined graphically, descriptively, with t-tests, and with Mann-Whitney tests. Graphical analyses suggested differences among infants in magnitude and trajectories of linear HRV power. Three infants (diagnosed with coarctation of the aorta, transposition of the great arteries, and double-outlet right ventricle) demonstrated significantly higher post-operative levels of linear HRV power compared with pre-operative levels. One infant (diagnosed with hypoplastic left heart syndrome) demonstrated reduced HRV post-operatively. Non-linear measures showed more abnormal Poincare plots post-operatively (11%-60%) than pre-operatively (0%-18%), revealing increased sympathetic activity following surgery in these infants. The infant with hypoplastic left heart syndrome showed the highest percentage of abnormal plots both pre- and post-operatively (18% and 60%, respectively). These findings revealed differences in linear and non-linear HRV by cardiac defect. Additional studies with larger sample sizes and multiple longitudinal assessments are needed to enhance our understanding of relationships between specific cardiac defects and autonomic function. Knowledge about associations between early autonomic function and type of cardiac defect will assist with tailoring early interventions to optimize neurodevelopment in this vulnerable population.