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 ~65 years, the rebound of RR50, SDmeans and the ~3.6 sec spectral power (“HF”(24h)) may represent particularly healthy long-lived subjects. Age-related changes are similar for males and females for SDANNs, SDmeans and the ~3.6 sec power, but differ for the ~10.5 sec/~3.6 sec power ratio which peaks ~46 years for males vs. ~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