Chronomes (rhythms, chaos, and age trends) of human heart rate variability in both genders

Heart rate variability (HRV) may reflect autonomic nervous activity. From 24-hour Holter ECG records on 339 healthy subjects (222 M, 117 F), 3-92 years of age, time- and frequency-domain and chaotic measures (correlation dimension, CD, and complexity) of HRV were computed. Changes with age are not invariably linear: following a decrease until approximately 65 years, the rebound of RR50, SDmeans and the approximately 3.6 sec spectral power (`HF' (24 h)) may represent particularly healthy long-lived subjects. Age-related changes are similar for males and females for SDANNs, SDmeans and the approximately 3.6 sec power, but differ for the approximately 10.5 sec/approximately 3.6 sec power ratio which peaks approximately 46 years for males vs. approximately 34 years for females. Changes with age in CD are more pronounced by night than by day. The `sympathetic-parasympathetic' antiphase corresponds to physiologic considerations. Changes in HRV may contribute to the increased prevalence of cardiovascular disease with age.