Heart Rate Variability analysis in normal infants and infants with single ventricle anatomy using power spectral density

Heart Rate Variability (HRV) is a measure of the magnitude of autonomic cardiac tone produced by sympathetic and parasympathetic innervations. Power spectral density estimates in adults use traditional low frequency (LF) and high frequency (HF) bands to assess HRV as an indicator of increased risk of cardiac mortality. Studies of altered HRV in infants suggest that classic methods need modification for application in the pediatric population. 24-hour ECG data was collected for 27 normal infants (Group I) and 26 infants with congenital heart defects (Group II) and analyzed in five-minute segments using the Lomb periodogram. Traditional adult frequency ranges were modified for expansion of the HF range and a significant difference was found in Group I and Group II infants. Congenital differences in sympathetic tone remain post-procedure and normal development of parasympathetic tone was not seen in infants with the single ventricle anatomy.