Differential effects of aging on heart rate variability and blood pressurevariability

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 w as not accounted for as a possible confounding factor. This study was desig ned to characterize the relationship between age and short-term heart rate (HR) and blood pressure (BP) variability, independently of the "physiologic al" rise in BP associated to aging. The study was carried out in 65 "normot ensive" (RP less than or equal to 140/80 mm Hg) healthy subjects, ranging i n 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 = res piratory peak +/- 0.05 Hz) components of HR and BP variability were assesse d using fast-Fourier spectral analysis. Transfer-function analysis between systolic BP and HR variability permitted the calculation of the gain of bar oreflex sensitivity. Significant results of this study include a continuous and linear decline with age of normalized LF spectral power of HR in the s tanding position and of normalized HF spectral power of HR during paced bre athing. No correlation was found between age and BP variability, except for LF diastolic BP spectral power in the standing position. The baroreflex ga in was negatively correlated with age. The effect of aging on autonomic ner vous system cardiac control is progressive and continuous throughout an 18- 80 years age range. Although the aging process diminished HR variability an d diastolic BP variability, it had no influence on systolic BP variability.