DEVELOPMENTAL PATTERNS OF HEART-RATE AND VARIABILITY IN PREMATURELY-BORN INFANTS WITH APNEA OF PREMATURITY

At equivalent post-conceptional ages, prematurely-born infants have hi gher heart rates and reduced heart rate variability, relative to full- term neonates. premature birth might exert long-lasting effects on cen tral and peripheral mechanisms that control cardiovascular activity. W e assessed development of heart rate and heart rate variability in sym ptomatic preterm infants up to 6 months of age. Fifty 6.5-h evening re cordings of EKG and breathing were obtained from prematurely-born infa nts (gestational ages: 24-35 weeks). Cardiac R-R intervals were captur ed with a resolution of +/-0.5 msec. One-min epochs were selected from three periods of regular respiration in recordings from premature inf ants and 72 recordings of full-term infants at comparable post-concept ional ages. Mean heart rate and heart rate variability were determined for each recording. At 40 weeks post-conception, prematurely-born inf ants with apnea of prematurity showed higher heart rates and reduced h eart rate variability than did full-term neonates. These differences b etween premature and full-term infants persisted throughout the next 6 months in those infants born prior to 30 weeks gestation, and in thos e infants born at 30-35 weeks who experienced respiratory distress syn drome (RDS) during the neonatal period. The findings suggest that prem ature delivery, or complications thereof, exerts long-lasting effects on cardiac control.