Background : It is known that heart rate shows a complex behavior, attributed to the nonlinear nature of its generating and modulating system. Analyzing the nonlinear properties in the heart rate variability (HRV). may deepen the understanding of the pathophysiological modulation of HRV.
　Methods : In 34 patients (mean age 65±9 years, 20 ischemic heart disease, 4 cardiomyopathy, 3 valvular heart disease, 6 chest pain syndrome and one congestive heart failure due to renal dysfunction), a CM5 electrocardiogram was recorded from 5:00 to 6:00 AM by use of the digitalized monitoring system (FS-2100, Fukuda Denshi Co., Tokyo, Japan). With regard to the time series of RR intervals, two non-linear measures, the largest Lyapunov exponent and the correlation dimension were calculated. The following standard HRV index were also measured: 1). mean heart rate, 2) standard deviation of NN intervals (SDNN), 3) the percentage of differences between adjacent NN intervals > 50 msec (%NN50), 4) low frequency (LF, 0.04-0.15 Hz), 5) high frequency (HF, 0.15-0.40 Hz). The hemodynamic indices were compared with those heart rate variability measures.
　Results： The largest Lyapunov exponent decreased age-dependently, as well as SDNN or %NN50. The largest Lyapunov exponents were also correlated with SDNN (r=0.85, p<0.01). The patients were divided into two groups; elevated LVEDP (left ventricular end-diastolic pressure ≥ 14 mmHg, n=7). or normal LVEDP (<14 mmHg, n=24). Elevated LVEDP group showed lower SDNN and lower Lyapunov exponents, compared with normal LVEDP group. However, correlation dimensions were independent from hemodynamic parameters.
　Conclusion：Non-linear analysis can detect the hemodynamic impairment in patients with myocardial dysfunction. Therefore, this will be used for the purpose of sports medical check. (271 ward)

DESCENTE SPORTS SCIENCE Vol.22/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE