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Measuring Cardiac Autonomic Nervous System (ANS) Activity in Children
Published on: April 29, 2013
Normative values for circadian and ultradian cardiovascular rhythms in childhood
Charlotte Hadtstein1, Elke Wühl, Marianne Soergel
1University Children's Hospital, Im Neuenheimer Feld 151, 69120 Heidelberg, Germany.
Insights
This study reveals that most children have daily blood pressure rhythms, but puberty alters heart rate rhythms. Ultradian rhythms (shorter than 24 hours) in blood pressure and heart rate also change significantly with puberty.
Area of Science:
- Physiology
- Chronobiology
- Pediatric Health
Background:
- Circadian and ultradian rhythms are fundamental physiological processes influencing cardiovascular function.
- Understanding these rhythms in children is crucial for assessing cardiovascular health and development.
- Ambulatory blood pressure monitoring provides valuable insights into natural BP and heart rate variations over 24 hours.
Purpose of the Study:
- To investigate the prevalence and characteristics of 24-hour (circadian) and shorter (ultradian) rhythms of mean arterial blood pressure (BP) and heart rate (HR) in healthy children.
- To determine the influence of age and puberty on these cardiovascular rhythms.
- To analyze the coupling and timing between BP and HR rhythms.
Main Methods:
- Analysis of 24-hour ambulatory BP profiles from 938 healthy children aged 5 to 18 years.
- Application of Fourier analysis with cosine harmonics to identify rhythmicity, amplitude, and acrophase (peak time).
- Statistical analysis to assess the impact of puberty on rhythm prevalence and coupling.
Main Results:
- Ninety percent of children exhibited circadian BP rhythms, while circadian HR rhythmicity decreased with puberty (96% to 87%).
- Puberty significantly altered ultradian rhythms, increasing 12- and 6-hour BP and HR rhythms, and decreasing 8-hour BP rhythms.
- Strong associations were observed between BP and HR rhythms in prevalence and timing, with minimal time lags between their peaks.
Conclusions:
- Children exhibit distinct circadian and ultradian rhythms in BP and HR, which are modulated by puberty.
- The findings highlight the dynamic nature of cardiovascular rhythms during childhood development.
- The tight coupling between BP and HR rhythms suggests integrated physiological regulation.
Abstract:
To assess the prevalence and characteristics of physiological circadian (24-hour) and ultradian (12-, 8-, and 6-hour) rhythms of mean arterial blood pressure (BP) and heart rate (HR), we analyzed 24-hour ambulatory BP profiles from 938 healthy school children aged 5 to 18 years. Cosine harmonics were fitted by Fourier analysis, and an amplitude and acrophase (time of peak) were calculated for each rhythm. Ninety percent of children displayed circadian rhythmicity of BP, independent of age, whereas circadian HR rhythmicity decreased with puberty from 96% to 87% (P<0.0001). Puberty had marked effects on the prevalence of ultradian rhythmicity: 12- and 6-hour rhythms increased for BP (27% to 47%, P<0.0001; 18% to 25%, P=0.01) and HR (36% to 47%, 17% to 31%, both P=0.001), whereas 8-hour BP rhythms decreased (34% to 23%, P=0.002). Median amplitudes were 10.1, 5.9, 5.6, and 5.2 mm Hg for the 24-, 12-, 8-, and 6-hour BP rhythms, respectively, and 13.4, 7.7, 6.8, and 6.4 bpm for HR. The acrophase occurred at approximately 14:00 hours, 8:00 hours, 5:30 hours, and 2:00 hours (military time) for the four BP rhythms, and at 13:30 hours, 08:30 hours, 01:50 hours, and 02:00 hours for HR. For the combined curve, the peak-trough difference was 25.9 mm Hg and 35 bpm for BP and HR, respectively, with the peaks occurring at 13:50 hours and 13:10 hours. There was marked association between BP and HR rhythms, both for prevalence (P<0.0001 for coupling of BP and HR rhythms of the same period length) and timing, with a median time lag of BP after HR acrophase of only 21, 16, 13, and 5 minutes for the four rhythms, respectively.
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