Aging effects on cycle length dependence of heart rate variability

The effects of normal aging on heart rate variability (HRV) and on the cycle length (CL) dependency of HRV were assessed in 24 hour recordings obtained from 66 subjects divided into 3 groups: healthy young subjects, healthy elderly subjects and age matched elderly patients with ischemic heart disease (IHD). The results show: (1) 24 hour HRV decreases with normal aging; (2) the CL dependency of HRV also decreases with normal aging; (3) CL dependency persists in the healthy elderly to a variable degree, even at a very advanced age, but not in age-matched elderly patients with IHD, and (4) the degree of decrease in HRV and in CL dependency differed for different HRV measures, presumably reflecting differences in underlying autonomic mechanisms