Longitudinal assessment of heart rate variability in very low birth weight infants during their NICU stay

Asif Z. Khattak, Nikhil S. Padhye, Amber L. Williams, Robert E. Lasky, Fernando R. Moya, M. Terese Verklan

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Background: Maturation of the autonomic nervous system has not been studied in high-risk very low birth weight (VLBW) infants in the first few weeks of life. Aim: To characterize developmental changes in autonomic nervous system activity of high-risk VLBW infants from 23 to 38 weeks post-menstrual age by measuring heart rate variability (HRV). Study design and subjects: In this prospective cohort study 38 infants admitted to Children's Memorial Hermann Hospital NICU were longitudinally followed weekly or biweekly. Heart period data were recorded while infants were resting in active sleep. Outcome measures: Growth of spectral power of HRV in low-frequency (0.05-0.25 Hz) and high-frequency (0.25-1.00 Hz) bands was modeled with linear mixed-effects models. The high-frequency power provides a measure of respiratory sinus arrhythmia (RSA). Results: Low-frequency power increases with post-menstrual age, and intubated infants have lower HRV. The increase in low-frequency power is faster (0.50 ± 0.12 dB/week) than the increase in RSA (0.17 ± 0.09 dB/week). Conclusion: This longitudinal data exhibits developmental maturation of the RSA and of the low-frequency power of HRV in high-risk VLBW infants.

Original languageEnglish (US)
Pages (from-to)361-366
Number of pages6
JournalEarly Human Development
Issue number6
StatePublished - Jun 2007
Externally publishedYes


  • Respiratory sinus arrhythmia
  • Spectral analysis
  • VLBW infants
  • Vagal tone

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health
  • Obstetrics and Gynecology


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