|Budget Amount *help
¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1999 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1998 : ¥1,400,000 (Direct Cost : ¥1,400,000)
To investigate nonlinear and linear components of arterial pressure and heart rate variability (HRV) in essential hypertension, we constructed the chaos and spectral analysis system of the time series data, and applied it on clinical settings. After taking the R-R interval data of non-invasive continuous blood pressure monitor or Holter ECG in the computer, both the chaos and spectral analyses were performed. The following results were obtained by using this system.
(1) Chaos and spectral analyses of HRV were performed in essential hypertensive subjects (EHT) and normotensive controls (NT) to investigate the serial changes of sympathetic nerve activity during head-up tilting. The %HF was decreased in EHT at rest, and head-up tilting increased the LF/HF and reduced the %HF in both groups. On the other hand, the correlation dimension, an index of complexity, was lower at rest in EHT than in NT, and did not change in EHT in response to head-up tilting, but decreased in NT. Lyapunov exponents, an index of sensitive dependence on initial condition, did not change during head-up tilting in both groups.
(2) Circadian changes of chaos and spectral components were investigated in outpatient HT and NT. The %HF did not show circadian changes in HT, but it decreased during the daytime in NT. The LF/HF showed an opposite change to the %HF. On the other hand, the correlation dimension decreased in the daytime or in the evening in both NT and adult HT, but did not change in elderly HT. The Lyapunov exponents were significantly smaller in the elderly HT than in elderly NT during nighttime.
In conclusion, the chaos components included in the HRV seems to reflect the different aspect of HRV from spectral components.