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Maturational changes in heart rate and heart rate variability in low birth weight infants
R Sahni1, K F Schulze, S Kashyap
1Department of Pediatrics, College of Physicians and Surgeons, Columbia University, New York, NY, USA.
Insights
Heart rate variability in low birth weight infants increases with postconceptional age, indicating maturing autonomic cardio-regulatory activity during sleep. This development shows improved control over heart rate patterns as infants grow.
Area of Science:
- Neonatal physiology
- Autonomic nervous system development
- Sleep studies
Background:
- Understanding neural mechanisms of heart rate variability (HRV) during sleep is crucial for assessing infant development.
- Low birth weight infants exhibit unique developmental trajectories in physiological regulation.
Purpose of the Study:
- To investigate the maturation of neural mechanisms underlying heart rate variability in low birth weight infants during quiet and active sleep.
- To correlate changes in HRV with postconceptional age in this vulnerable population.
Main Methods:
- Continuous electrocardiographic recordings were obtained for 6 hours in 61 low birth weight infants (795-1600 g birth weight).
- Simultaneous minute-by-minute behavioral activity state assignments (quiet vs. active sleep) were performed.
- Time and frequency domain measures of cardiac interbeat interval variability were analyzed.
Main Results:
- Heart rate decreased during quiet sleep, while HRV measures (time and frequency domain) increased with postconceptional age (31-38 weeks).
- Global variability (SD of R-R intervals) and high-frequency variability increased with age in quiet sleep.
- The incidence of sustained accelerations/decelerations in interbeat intervals increased, while no-change intervals decreased, correlating with postconceptional age.
Conclusions:
- Postconceptional age is a significant factor in the maturation of heart rate variability in low birth weight infants.
- Observed changes in HRV and interbeat interval patterns suggest developing autonomic cardio-regulatory activity from 31-38 weeks.
- These findings provide insights into the neurodevelopmental maturation of cardiovascular control during sleep in preterm infants.
Abstract:
To provide insight into the maturation of neural mechanisms responsible for variability in heart rate during quiet and active sleep, 6-hour continuous electrocardiographic recordings and simultaneous minute-by-minute behavioral activity state assignments were performed in 61 healthy, growing low birth weight infants. The infants weighed 795-1600 g at birth and ranged between 31-38 weeks in postconceptional age. During this age interval there was a decrease in heart rate during quiet sleep and an increase in both time domain and frequency domain measures of the variability in cardiac interbeat intervals. In quiet sleep, global variability, measured as SD of R-R intervals, increased in relation to age, as did higher frequency variability, measured as the square root of the mean of squared successive differences in R-R intervals. Developmental changes in the 0.5-2.0 Hz spectral power band of RR-interval variability, another measure of high frequency variability, paralleled the changes seen in the time domain measure. Evaluation of patterns of changes in the magnitude and direction of successive interbeat intervals provided evidence that the incidence of sustained accelerations or decelerations increased whereas the incidence of no change in consecutive RR-intervals decreased as infants matured. Among the various measures of heart rate variability, the incidence of sustained change and no change in successive interbeat intervals were most closely related to postconceptional age in both sleep states. The overall decrease in heart rate, increase in heart rate variability, and increase in the pattern of changes in interbeat interval with postconceptional age are consistent with the maturation of the autonomic cardio-regulatory activity from 31-38 weeks age.