title: Unexpected course of nonlinear cardiac interbeat interval dynamics during childhood and adolescence.
abstract: The fluctuations of the cardiac interbeat series contain rich information because they reflect variations of other functions on different time scales (e.g., respiration or blood pressure control). Nonlinear measures such as complexity and fractal scaling properties derived from 24 h heart rate dynamics of healthy subjects vary from childhood to old age. In this study, the age-related variations during childhood and adolescence were addressed. In particular, the cardiac interbeat interval series was quantified with respect to complexity and fractal scaling properties. The R-R interval series of 409 healthy children and adolescents (age range: 1 to 22 years, 220 females) was analyzed with respect to complexity (Approximate Entropy, ApEn) and fractal scaling properties on three time scales: long-term (slope β of the power spectrum, log power vs. log frequency, in the frequency range 10(-4) to 10(-2) Hz) intermediate-term (DFA, detrended fluctuation analysis, α(2)) and short-term (DFA α(1)). Unexpectedly, during age 7 to 13 years β and ApEn were higher compared to the age <7 years and age >13 years (β: -1.06 vs. -1.21; ApEn: 0.88 vs. 0.74). Hence, the heart rate dynamics were closer to a 1/f power law and most complex between 7 and 13 years. However, DFA α(1) and α(2) increased with progressing age similar to measures reflecting linear properties. In conclusion, the course of long-term fractal scaling properties and complexity of heart rate dynamics during childhood and adolescence indicates that these measures reflect complex changes possibly linked to hormonal changes during pre-puberty and puberty.
authors.affiliation: Integrated Curriculum for Anthroposophic Medicine, University of Witten/Herdecke, Witten, Germany. d.cysarz@rhythmen.de
authors.forename: Dirk
authors.initials: D
authors.lastname: Cysarz
authors.forename: Maijana
authors.initials: M
authors.lastname: Linhard
authors.forename: Friedrich
authors.initials: F
authors.lastname: Edelhäuser
authors.forename: Alfred
authors.initials: A
authors.lastname: Längler
authors.forename: Peter
authors.initials: P
authors.lastname: Van Leeuwen
authors.forename: Günter
authors.initials: G
authors.lastname: Henze
authors.forename: Georg
authors.initials: G
authors.lastname: Seifert
mesh_terms: D000293:Adolescent; D000375:Aging / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007223:Infant; D008297:Male; D017711:Nonlinear Dynamics; D012737:Sex Factors; D055815:Young Adult