Seasonal variation in 1/f fluctuations of heart rate in asthmatic children

Area of Science:

• Pediatric Pulmonology
• Chronobiology
• Autonomic Nervous System Function

Background:

• Asthma symptoms in children can be influenced by seasonal chronobiological changes.
• Previous research indicated seasonal variations in heart rate variability (HRV) power spectrum bands (LF and HF) in asthmatic children.
• Heart rate (HR) l/f fluctuations are a novel index of autonomic function from a chronobiological perspective.

Purpose of the Study:

• To investigate if heart rate (HR) l/f fluctuations in asthmatic children exhibit seasonal variations.
• To compare seasonal changes in HR l/f fluctuations between asthmatic and healthy children.

Main Methods:

• Analysis of 24-hour ambulatory electrocardiograms (AECG) from 87 asthmatic and 104 healthy children.
• HR l/f fluctuations were analyzed using the MemCalc system during awake, asleep, and 24-hour periods across four seasons.
• Assessment of seasonal variations in the mean of normal-to-normal R-R intervals.

Main Results:

• No significant seasonal variations in HR l/f fluctuations were detected in either asthmatic or control groups for any analyzed period.
• Asthmatic children exhibited a significant seasonal variation in the mean of normal-to-normal R-R intervals over 24 hours.
• Despite seasonal HR variations, HR l/f fluctuations remained constant in asthmatic children.

Conclusions:

• HR l/f fluctuations do not appear to vary seasonally in asthmatic children, unlike overall heart rate.
• Seasonal changes in autonomic function, as measured by HR l/f fluctuations, may not be a significant factor in pediatric asthma seasonality.
• Further research is needed to understand the complex interplay between asthma, seasonality, and autonomic regulation in children.