Maturation of heart rate and blood pressure variability during sleep in term-born infants

Area of Science:

• Cardiovascular physiology
• Autonomic nervous system function
• Infant development

Background:

• Abnormal blood pressure regulation is linked to Sudden Infant Death Syndrome (SIDS).
• Normative data on infant blood pressure control development are lacking.
• Understanding autonomic control maturation is crucial for infant health.

Purpose of the Study:

• To assess the maturation of autonomic control of blood pressure and heart rate during sleep in the first six months of life.
• To establish normative data for infant cardiovascular autonomic regulation.
• To identify potential markers for impaired autonomic function in infants.

Main Methods:

• Longitudinal study of 31 term infants at 2-4 weeks, 2-3 months, and 5-6 months postnatal age.
• Daytime polysomnography including blood pressure and heart rate variability (BPV and HRV) recordings during quiet (QS) and active sleep (AS).
• Assessment of autonomic control using spectral indices (LF, HF, total power, LF/HF ratio) under baseline and head-up tilt conditions.

Main Results:

• Heart rate variability (HRV) increased with age, indicating strengthened parasympathetic control.
• Blood pressure variability (BPV) showed decreased sympathetic vascular modulation (LF/HF ratio) with age.
• Changes in autonomic control were observed in both baseline and tilt conditions, and differed between QS and AS.

Conclusions:

• Infant cardiovascular autonomic control undergoes significant maturation within the first six months of life.
• Sympathetic vascular modulation decreases, and parasympathetic heart rate control strengthens with age.
• These normative data can aid in early identification of autonomic dysfunction, potentially in conditions like SIDS.