Differential effects of aging on heart rate variability and blood pressure variability.

Previous studies investigating autonomic cardiovascular control in elderly persons usually included analysis of R-R interval but not of blood pressure variability. "Physiological" blood pressure rise during the aging process was not accounted for as a possible confounding factor. This study was designed to characterize the relationship between age and short-term heart rate (HR) and blood pressure (BP) variability, independently of the "physiological" rise in BP associated to aging. The study was carried out in 65 "normotensive" (BP< or =140/80 mm Hg) healthy subjects, ranging in age from 18 to 80 years. BP and HR were recorded at rest with a Finapres device. Low-frequency (LF = 0.066 to 0.129 Hz) and high-frequency (HF = respiratory peak +/-0.05 Hz) components of HR and BP variability were assessed using fast-Fourier spectral analysis. Transfer-function analysis between systolic BP and HR variability permitted the calculation of the gain of baroreflex sensitivity. Significant results of this study include a continuous and linear decline with age of normalized LF spectral power of HR in the standing position and of normalized HF spectral power of HR during paced breathing. No correlation was found between age and BP variability, except for LF diastolic BP spectral power in the standing position. The baroreflex gain was negatively correlated with age. The effect of aging on autonomic nervous system cardiac control is progressive and continuous throughout an 18-80 years age range. Although the aging process diminished HR variability and diastolic BP variability, it had no influence on systolic BP variability.