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Heart rate and heart rate variability during sleep in small-for-gestational age newborns
L Spassov1, L Curzi-Dascalova, J Clairambault
1INSERM, Hôpital A. Béclère, Clamart, France.
Insights
Small-for-gestational age (SGA) newborns exhibit altered heart rate (HR) and HR variability during sleep compared to appropriate-for-gestational age (AGA) newborns, indicating potential autonomic nervous system dysregulation. These findings suggest differences in sympathetic and parasympathetic control may be linked to increased metabolic rates in SGA infants.
Area of Science:
- Neonatal Physiology
- Autonomic Nervous System Function
- Fetal Development
Background:
- Intrauterine growth retardation (IUGR) can impact fetal development and long-term health.
- Heart rate (HR) and HR variability (HRV) are key indicators of autonomic nervous system (ANS) function in newborns.
- Sleep states significantly influence cardiovascular regulation in infants.
Purpose of the Study:
- To investigate the influence of IUGR on HR and HRV during sleep in newborns.
- To compare ANS control mechanisms between small-for-gestational age (SGA) and appropriate-for-gestational age (AGA) infants.
- To identify potential differences in sympathetic and parasympathetic modulation in SGA neonates.
Main Methods:
- Polygraphic recordings were conducted during sleep in SGA and AGA newborns (37-41 wk conceptional age).
- RR intervals were analyzed using short-time Fourier transform in high, mid, and low frequency bands.
- Comparisons were made between SGA and AGA groups, and between active and quiet sleep states.
Main Results:
- SGA newborns demonstrated significantly shorter RR intervals and lower HR variability across most frequency bands during both active and quiet sleep compared to AGA newborns.
- Quiet sleep was associated with longer RR intervals and higher high-frequency variability in both groups.
- Low-frequency variability was reduced in quiet sleep, particularly in AGA newborns.
Conclusions:
- SGA newborns exhibit significant modifications in both sympathetic and parasympathetic heart rate control during sleep.
- Despite differences in HR and HRV, central nervous system (CNS) control of HR appears maintained in SGA infants.
- Altered HR and HRV in SGA infants may be associated with an augmented metabolic rate compared to AGA infants.
Abstract:
To assess the influence of intrauterine growth retardation on heart rate (HR) and HR variability during sleep, we performed polygraphic recordings in 10 small-for-gestational age (SGA) and 16 appropriate-for-gestational age (AGA) newborns. Both groups were clinically and neurologically normal and were at 37 to 41 wk conceptional age. RR intervals were analyzed using the short-time Fourier transform in three frequency bands: 1) high frequency, with a period 3-8 heartbeat; 2) mid frequency, with a period 10-25 heartbeat; and 3) low frequency, with a period 30-100 heartbeat. In both active and quiet sleep, SGA newborns significantly differed from AGA newborns by having a shorter RR interval (p < 0.01) and lower amplitude of HR variability in all bands (p < 0.05) except low frequency in quiet sleep. Quiet sleep differed from active sleep by having a longer RR interval (p < 0.05), higher high-frequency variability (p < 0.02) in both SGA and AGA newborns, and lower low-frequency variability (p < 0.005 for AGA newborns). Our data give evidence of clear modifications of both sympathetic and parasympathetic HR control in the at-risk SGA population. Similarity of between-state characteristics suggests maintained CNS control of HR in SGA as well as in AGA newborns. We speculate that between-group HR and HR variability differences may be related to augmented metabolic rate in SGA compared with AGA newborns.