title: Circadian dynamics of heart rate and physical activity in patients with heart failure.
abstract: The present study was designed to develop a method to continuously measure Holter electrocardiogram (ECG) and physical activity in terms of metabolic costs to examine circadian dynamics of RR intervals and physical activity in patients with heart failure. A total of 7 healthy subjects and 3 heart failure patients performed cardiopulmonary exercise test using four-stage graded treadmill walking at 0% grade to examine whether the acceleration signals in the vertical direction could reflect actual body energy expenditure during physical activity. Then, using this new method, 24-hr monitorings of ECG and physical activity were performed in 24 inpatients with heart failure while they were allowed to walk around freely. Our results showed the integral of rectified acceleration signals was closely correlated with actual metabolic cost in all subjects. Instantaneous changes in heart rate were quite concordant with physical activity. As compared with the asymptomatic patients (n = 12), the symptomatic patients (n = 12) had lower energy expenditure during 8-hr daytime periods but higher mean heart rate. Furthermore, a more prominent ultradian rhythm of circadian changes in heart rate and physical activity was found in 50% of all subjects studied. The simultaneous analysis of Holter ECG and physical activity as the same time series revealed that in patients with heart failure, sympathovagal balance shifted toward sympathotonic conditions and their physical activity could become subject to intrinsic ultradian dynamics of body's homeostasis.
authors.affiliation: The Second Department of Internal Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan.
authors.forename: Tsugiyoshi
authors.initials: T
authors.lastname: Yamazaki
authors.forename: Hidetsugu
authors.initials: H
authors.lastname: Asanoi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ueno
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Yamada
authors.forename: Junya
authors.initials: J
authors.lastname: Takagawa
authors.forename: Tomoki
authors.initials: T
authors.lastname: Kameyama
authors.forename: Tadakazu
authors.initials: T
authors.lastname: Hirai
authors.forename: Takashi
authors.initials: T
authors.lastname: Nozawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Inoue
mesh_terms: D001944:Breath Tests; D002940:Circadian Rhythm / Q000502:physiology*; D015716:Electrocardiography, Ambulatory / Q000379:methods; D004734:Energy Metabolism / Q000502:physiology; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000378:metabolism / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D011237:Predictive Value of Tests