Heart rate variability in infants subsequently suffering sudden infant death syndrome (SIDS)

To study the role of the autonomic cardiovascular control in SIDS the heart rate variability (HRV) was analysed from 24 tape recordings made from a prospective population-based study on 16 term and one preterm infant suffering SIDS and compared to similar data on 23 control infants matched on birthweight, gestation and postnatal age. The number of regular breathing segments was lower in the SIDS cases than in controls (P = 0.02). No significant differences were found between the SIDS cases and their controls for average heart rate, median breathing rate, indices of overall and beat-to-beat HRV. Neither were significant intergroup differences found when the subjects were divided into neonatal and postneonatal subgroups. Analysis of HRV by power-spectral techniques did not show any significant differences between SIDS cases and controls for the general distribution of power or for the respiratory HRV. Analysis of HRV did not differentiate infants destined to die of SIDS from surviving controls in the same population.