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Development of heart rate dynamics during sleep-waking states in normal infants
V L Schechtman1, R K Harper, R M Harper
1Brain Research Institute, UCLA School of Medicine 90024-1761.
Insights
Cardiac R-R interval dynamics in infants show a temporary loss of normal patterns around 1 month of age. This change in heart rate variability may indicate increased vulnerability in healthy infants after the neonatal period.
Area of Science:
- Cardiology
- Pediatrics
- Developmental Biology
Background:
- Alterations in cardiac rate dynamics are observed in "at-risk" infant populations, including those who die from sudden infant death syndrome.
- Understanding normal cardiac rate maturation is crucial for identifying potential health risks.
Purpose of the Study:
- To examine the maturation of cardiac rate dynamics in normal infants during sleep-waking states over the first six months of life.
- To investigate changes in heart rate variability patterns and their potential implications for infant health.
Main Methods:
- Analyzed 12-hour recordings of cardiac R-R intervals in 24 normal full-term infants at multiple time points from 1 week to 6 months of age.
- Utilized Poincaré plots to visualize cardiac R-R interval dynamics and analyzed interval dispersion after long and short preceding intervals.
Main Results:
- Neonatal infants exhibited a distinct Poincaré plot pattern, similar to older infants and adults.
- This pattern temporarily disappeared between 1 week and 1 month of age, then gradually returned starting at 2 months.
- Infants at 1 month showed Poincaré plot patterns resembling those of "at-risk" populations, including those who died of sudden infant death syndrome.
Conclusions:
- Normal infants experience a transient disruption in cardiac rate dynamics around 1 month of age.
- This temporary pattern shift may signify a period of increased vulnerability in healthy infants post-neonatal period.
- Further research is warranted to understand the clinical significance of these transient changes in heart rate variability.
Abstract:
Previous studies show alterations in the dynamic patterns of cardiac rate in several "at-risk" populations, including apparently healthy infants who subsequently die of the sudden infant death syndrome. In the present study, we examined the maturation of cardiac rate dynamics in normal infants during sleep-waking states over the first 6 mo of life. Instantaneous changes in cardiac R-R intervals were examined in 12-h recordings of 24 normal full-term infants; each infant was recorded at 1 wk and at 1, 2, 3, 4, and 6 mo of age. Scatter plots, consisting of each cardiac R-R interval plotted as a function of the previous interval (Poincaré plots), were constructed for each sleep-waking state in each recording. Analyses of variance were performed on the dispersion of intervals after long and short R-R intervals. In neonates, Poincaré plots showed significantly more next-interval dispersion after a long R-R interval than after a short interval, a pattern similar to those observed in older infants and in healthy adults. However, between 1 wk and 1 mo of age, this pattern disappeared and returned gradually beginning at 2 mo of age. The scatter of points in Poincaré plots of infants 1 mo of age approached the patterns of at-risk populations, including infants who subsequently died of the sudden infant death syndrome. These patterns at 1 mo may be indicative of increased vulnerability in normal infants after the neonatal period.