Abstract
It is known that the R-R interval of the heart rate is variable even in the stationary state and shows a fluctuation of 1/f. A detailed investigation of the spectrum of this fluctuation shows that there are two peak levels at a particular frequency. band. It has been clarified through recent clinical applications that the highfrequency (HF) component of these two peaks reflects the activity of parasympathetic nerves while the lowfrequency (LF) component reflects the activity of sympathetic nerves. Thus, separate quantification of autonomic nerves into sympathetic and parasympathetic nerves is possible and their activities can be traced over time. Using the maximum entropy method (MEM) we recently conducted a spectral analysis of heart rate variation of about a 0.2 million beats, which had been obtained by connecting the hemodialysed patient to a Holter electrocardiograph for 48 consecutive hours and stored in a floppy disk. Moreover, we also made a regression curve, using time series results of HF and LF, by the periodic regression method. Fast fourier transformation (FFT) was used to construct the curve and the circadian rhythm pattern in sympathetic and parasympathetic nerves was investigated by cycle and type variation. These studies showed that the activities of both sympathetic and parasympathetic autonomic nerves in hemodialysed patients varied according to a 48 hour cycle. Furthermore, the sympathetic nervous system was hyperactive on the day of hemodialysis while the parasympathetic nervous system was hyperactive on non-hemodialysis days. On the other hand, the cycle of variation in heart rate is represented as a sum total of all activities and a 24-hour circadian rhythm was thus presumed to be maintained.
