Artikel
Prevalence of Circadian and Ultradian Cardiovascular Rhythms in Childhood
Prävalenz zirkadianer kardiovaskulärer Rhythmen im Kindesalter
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Autoren
Veröffentlicht: | 11. November 2004 |
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Gliederung
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Aim
The aim of this study was to assess the prevalence and characteristics of physiological circadian (24h) and ultradian (12h and 8h) rhythms of blood pressure (BP) and heart rate (HR) across childhood.
Methods
We analyzed 24h ABPM profiles from 946 healthy school children aged 5-20 years. Cosine harmonics were fitted by Fourier analysis, and tested for significance in each subject. Each harmonic is characterized by an amplitude and an acrophase (time of peak expressed as hours from midnight).
Results
BP amplitudes were 10±3.5, 6±2 and 6±2 mmHg for the 24, 12 and 8h rhythms respectively. The acrophase peaks occurred at 14.00±1.6h for the 24h, at 8.00±1.7h for the 12h and at 2.30±1.6h for the 8h BP rhythm. The fraction of subjects exhibiting significant 24h BP rhythms was constant across childhood at about 90%, whereas the prevalence of 24h HR rhythms decreased with age (96 to 87%, p<0.0001). The prevalence of 12h rhythms increased with age for both BP (27 to 47%, p<0.0001) and HR (36 to 47%, p=0.001), whereas the prevalence of 8h BP rhythms decreased around puberty (34% to 23%, p=0.002). Coexisting 24, 12 and 8h BP and HR rhythms were observed more frequently than expected by chance. Coupling was strongest for BP and HR rhythms of the same period length (p<0.0001). The timing of HR acrophases was tightly coupled to BP acrophases, with a mean (±SD) time lag of 25±100 min for 24h, 20±77 min for 12h and 11±50 min for 8h rhythms. In the subjects exhibiting significant cardiovascular rhythms, the amplitudes, acrophases and time lags between BP and HR rhythms were independent of gender and body size for each wavelength studied.
Conclusion
Between age 5 and young adulthood, 90% of healthy children exhibit circadian rhythms of BP and HR. 12h ultradian BP or HR rhythms become more, and 8h BP rhythms less prevalent in puberty. The presence and timing of individual BP and HR rhythms is closely coupled.