Emi Yuda

Association Between Regional Difference in Heart Rate Variability and Inter-prefecture Ranking of Healthy Life Expectancy: ALLSTAR Big Data Project in Japan

As a physiological big-data project named ALLSTAR, we have developed a 24-hr ambulatory electrocardiogram database of 81,615 males and 103,038 females (≥20 yr) from all over Japan. With this database, we examined if regional differences in heart rate (HR) and HR variability (HRV) are associated with the inter-prefecture rankings of healthy life expectancy (HALE) and of average life expectancy (ALE) in Japan. According to reports by the Japanese Ministry of Health, Labour and Welfare (2013), subjects in each sex were grouped into short, middle, and long HALE and ALE tertiles by their living prefectures. Standard deviation of 24-h normal-to-normal R-R intervals (SDNN) increased progressively with increasing HALE tertiles in both sexes (Ps < 0.001), while it showed no consistent associations with ALE. Conversely, HR decreased progressively with increasing ALE tertiles in females (P < 0.001), while it showed no consistent association with HALE. These suggest HRV may reflect a biological property relating to long HALE.

Characteristics of basal heart rate during daily life: relationships with age, sex, and mean heart rate

Vast heart rate (HR) data during daily activities are being accumulated with widespread use of wearable sensors. To interpret the meaning of these HR data, the reference point of HR in individual subject is required. Although resting HR has been used for this purpose, the definition of resting HR has not been established and particularly, the effects of time of the day (circadian rhythm) on resting HR have not been considered. One of the other candidates for the reference point may be basal HR, i.e., the lowest HR in the day. In the present study, we therefore investigated the characteristics of basal HR by examining the effects of age and sex on basal HR and the occurrence time of basal HR during 24 h in 113,341 males and 140,332 females extracted from a 24-h Holter ECG database of the Allostatic State Mapping by Ambulatory ECG Repository (ALLSTAR). Although basal HR decreases with age until 20 yr old in both sexes, it increases slightly with advancing age thereafter. Although the clock time to reach basal HR appears between 02 and 05 h on average, it shows progress or delay depending on the time of life. The difference between 24-h mean and basal HR decrease linearly with age, suggesting that age-dependent decline in the increases in HR with daily activities can be detected by using basal HR as the reference point.

Blunted cyclic variation of heart rate predicts mortality risk in post-myocardial infarction, end-stage renal disease, and chronic heart failure patients

Abstract Aims Cyclic variation of heart rate (CVHR) associated with sleep-disordered breathing is thought to reflect cardiac autonomic responses to apnoeic/hypoxic stress. We examined whether blunted CVHR observed in ambulatory ECG could predict the mortality risk. Methods and results CVHR in night-time Holter ECG was detected by an automated algorithm, and the prognostic relationships of the frequency (FCV) and amplitude (ACV) of CVHR were examined in 717 patients after myocardial infarction (post-MI 1, 6% mortality, median follow-up 25 months). The predictive power was prospectively validated in three independent cohorts: a second group of 220 post-MI patients (post-MI 2, 25.5% mortality, follow-up 45 months); 299 patients with end-stage renal disease on chronic haemodialysis (ESRD, 28.1% mortality, follow-up 85 months); and 100 patients with chronic heart failure (CHF, 35% mortality, follow-up 38 months). Although CVHR was observed in ≥96% of the patients in all cohorts, FCV did not predict mortality in any cohort. In contrast, decreased ACV was a powerful predictor of mortality in the post-MI 1 cohort (hazard ratio [95% CI] per 1 ln [ms] decrement, 2.9 [2.2–3.7], P < 0.001). This prognostic relationship was validated in the post-MI 2 (1.8 [1.4–2.2], P < 0.001), ESRD (1.5 [1.3–1.8], P < 0.001), and CHF (1.4 [1.1–1.8], P = 0.02) cohorts. The prognostic value of ACV was independent of age, gender, diabetes, β-blocker therapy, left ventricular ejection fraction, sleep-time mean R-R interval, and FCV. Conclusion Blunted CVHR detected by decreased ACV in a night-time Holter ECG predicts increased mortality risk in post-MI, ESRD, and CHF patients.

Increase in random component of heart rate variability coinciding with developmental and degenerative stages of life

OBJECTIVE To adapt to a new environment or situation, biological systems explore the most convenient state while moving between attractors by the force of random fluctuation. From this concept, the random component in physiological signals is assumed to increase during developmental and degenerative stages of life. To examine this hypothesis, we measured the age-dependent changes in the random component of heart rate variability (HRV) in 24-h electrocardiography (ECG) big data and in patients with a developmental disorder (DD). APPROACH We measured separately regulated and random components of HRV with autoregressive (AR) model fitting, by which the ratio of random component as the fractional variance of AR residual time series. From the ALLSTAR database of about 304 000 ambulatory 24-h ECGs, we randomly extracted the data of 1930 men and 1987 women uniformly for all ages from 0 to 100 years old (100 cases per 5-year strata for each sex). Data were also obtained from male pediatric patients with DD (age 10-15 years). MAIN RESULTS While the variance of the regulated component of HRV increased from age 0 to 20, decreased with age until 40, and reached a plateau in both sexes, the ratio of the random component was high at birth, decreased with age until 35 in men and 30 in women, and increased again after 75 in men and 85 in women (P  <  0.0001 for all). In patients with a DD, the ratio of the random component was significantly lower than that in age-and-sex matched subjects in the database. SIGNIFICANCE We found that the ratio of the random component of HRV is increased during developmental and degenerative stages of life and that it may be reduced in DD patients during their development.

Acute effects of endurance exercise on nocturnal autonomic functions in sedentary subjects: a pilot study

Nocturnal heart rate variability (HRV) is thought to reflect healthy recovery function of the autonomic nervous system. Although exercise is recommended for health promotion, exercise itself decreases HRV. We studied acute effect of daytime exercise on nocturnal HRV in 5 healthy adults (age, 22–40 years; 2 female subjects) without regular exercise habit. Using a treadmill, they performed 30-min walking at 4 km/hr and 30-min running at 9 km/hr from 11 a.m. on different days at an interval of 2 weeks. On these days and a day without exercise (control), Holter electrocardiograms were recorded from 9 a.m. for 24 hr. The amplitudes of low-frequency (LF, 0.04–0.15 Hz) and high-frequency (HF, 0.15–0.45 Hz) components of HRV were measured continuously by complex demodulation and were averaged over periods of 11:00–11:30 a.m., 3 hr after going to bed, and time in bed at night. Exercise intensities of the walking and running were at 10% to 44% and 55% to 67% of heart rate reserve, respectively. During exercise, heart rate increased and LF and HF amplitudes decreased with exercise intensity. Nocturnal heart rate and LF and HF amplitude, however, showed no consistent changes with exercise intensity and their averages on the days of walking and running did not differ significantly from those of the control day. In conclusion, 30-min walking and running exercises performed in the morning had no significant acute effects on nocturnal heart rate or HRV.

Evaluation of nocturnal heart rate variability for strenuous exercise day using wearable photoelectric pulse wave sensor

In this study, we examined whether or not the strenuous exercise in the evening change nocturnal heart rate variability (HRV) and recovers. Subjects were 8 healthy men belonging to the mature futsal team (age: 35±3 years) and Futsal was held from 5:00 p.m. to 6:30 p.m. on Sunday. Pulse waves during sleeping were measured at home on exercise day and on control day. The mean pulse interval (MPI), standard deviation pulse interval (SDPI), low frequency component (LF, 0.04–0.15 Hz), high frequency component (HF, 0.15–0.45 Hz) and the ratio of LF to HF (LF/HF) were calculated from pulse interval time series every 30 min. As a result, MPI, SDPI, LF, HF of exercise day were significantly lower than control day (P<0.0001). LF/HF of exercise day was significantly higher than control day (P<0.05). Regarding change of HRV for every 30 min, MPI (P<0.05), SDPI (P=0.0003), LF (P=0.0038), HF (P<0.05) were observed significant changes. MPI and HF before wake-up did not reach the level of control day. It is thought that strenuous exercise in the evening promotes sympathetic nervous activity during night sleep and suggesting that pulse rate and HRV have not recovered by the wake-up time.

Assessment of Flow Mediated Dilation by Pulse Wave Conduction Delay

This study aimed at developing a new method for assessing flow mediated dilation (FMD) by bilateral differences in pulse conduction time. Delay in pulse conduction time (PCD) that accompanied FMD induced by forearm reactive hyperemia with 5-min avascularization was evaluated. PCD increased with FMD but the correlation coefficient between PCD and FMD was 0.33. PCD may have been influenced by unmeasured factors other than FMD.

Life Style Modification by Peer Monitoring of Physical Activity

We investigated whether peer monitoring of daily activities among a group of workplace colleagues will help to improve their daily physical activities. Peer monitoring of actigraphic data did not affect significantly exercise energy consumption or step count. It rather reduced the time of physical activities >3 Mets and increased heart rate during working hours. Peer monitoring of actigraphic among workplace colleagues may cause complicated psychologic effects and may not improve physical activities.

Physical and Psychophysiological Impacts of GPS Labor Management in Nursing Home Workers

Labor management based on global positioning systems (GPS) has become popular. To investigate the stress caused by GPS-labor management system, we studied its physical and psychophysiological impacts in nursing home workers. Despite that the use of GPS-labor management did not change physical activity it caused a reduction in heart rate and increases in parasympathetic indices of heart rate variability, which may be consistent with sustained alert response.

Longer lying position causes lower LF/HF of heart rate variability during ambulatory monitoring

Low-frequency-to-high-frequency ratio (LF/HF) of heart rate variability has been used as a maker of stress or sympathetic predominance in cardiac autonomic activity. Laboratory studies, however, indicate that LF/HF increases with standing and decreases with lying. We hypothesized that LF/HF in ambulatory monitoring is associated with the ratio of time in lying position during the monitoring (lying ratio). We examined this hypothesis using 47,624 ambulatory 24-h electrocardiograms recorded with 3-axis accelerograms in a large database of Allostatic State Mapping by Ambulatory ECG Repository (ALLSTAR) project. We found that LF/HF decreases with advancing lying ratio even after adjustment for the effects of age.