Diurnal heart rate variability in healthy subjects: effects of
aging and sex difference.
Yamasaki, Yoshimitsu, Mineo Kodama, Munehide Matsuhisa, Michihiko
Kishimoto, Hitoshi Ozaki, Akihiro Tani, Nobuyuki Ueda, Yoshio Ishida,
Takenobu Kamada.
First Department of Medicine, Osaka University School of Medicine,
2-2 Yamadaoka, Suita City, Osaka, 565, JAPAN, Osaka Police Hospital,
10-31 Kitayama-cho, Tennoji-ku, Osaka 543, JAPAN, Department of
Radiology & Nuclear Medicine, National Cardiovascular Center, 5-7
-1 Fujishiro-dai, Suita City, 565, JAPAN
APStracts 3:0038H, 1996.
Heart rate variability is increasingly being used as a marker of
impaired cardiac nerve function. However, the effects of aging and
gender on its circadian rhythm have not been established yet.
Circadian profiles of heart rate variability were evaluated for 105
healthy volunteers (63 males and 42 females, age 20 - 78 years) by
frequency domain analysis of 24 hour RR intervals obtained from a
holter ECG record to calculate low frequency (LF) and high frequency
(HF) components for several time periods as well as over 24 hours.
The LF components representing cardiac [beta]-adrenergic function
showed high values for the 8 AM - 12 PM period in male subjects and
12 AM - 12 PM period in female subjects. The HF component
representing parasympathetic function showed a peak for the 12 PM - 6
AM period in both male and female subjects independent of age. Male
subjects 20 - 29 and 50 - 59 years old showed significantly higher LF
components for the 8 AM - 6 PM period than age-matched female
subjects. Females aged 50 years and above showed significantly higher
HF in the daytime than age-matched males. The male subjects showed
consistently higher %LF (LF/ LF+HF) than the females regardless of
age. The total frequency (LF+HF) and LF components showed
consistently and highly significant correlation with age regardless
of the time periods. The HF components showed relatively weak but
significant correlation with age. The 24-hour %LF and the %LF during
the 12 AM - 12 PM period showed significant correlation with age.
These data indicate that the LF component is activated during the
daytime while the HF component is pronounced during the nighttime
especially in younger subjects, and these circadian profiles are
diminished in older subjects. LF during the daytime is pronounced in
young males and HF is relatively preserved in older female subjects.
These basic findings can help understand the diurnal profile of
cardiac nerve function and how it is affected by aging and sex
difference.
Received 8 November 1995; accepted in final form 5 January 1996.
APS Manuscript Number H1048-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 29 January 96