| Summary: | 碩士 === 中原大學 === 醫學工程學系 === 87 === Impairment of autonomic control of the cardiovascular system is frequency complication in chronic renal failure patients. Procedures based on changes in either blood pressure or heart rate in response to standard stimuli have been used to locate the defective part of the autonomic nervous system in patients undergoing regular hemodialysis(HD).Heart rate variability (HRV) is a recently introduced method for the quantitative description of the rhythmical components of cardiovascular variability. To purpose of this investigation was to determine non-invasively the alteration in autonomic cardiovascular control observed in chronic renal failure. Amplitude spectral of heart rate rhythmicity were estimated and integrated amplitudes of the low (0.04-0.15 Hz) and high frequency (0.15-0.4 Hz) component were computed. The normalized low-frequency spectral power was used as the index of sympathetic activity, the normalized high-frequency spectral power as the index of vagal activity and the low/high frequency power ratio as the index of sympathovagal balance of the study subjects.The study population consisted of 48 uremic patients without clear and obvious arrhythmia and 9 healthy controls were analyzed, and compared with before and after HD in postural change. The principle are as follows: (1)Heart rate increased significantly both healthy controls and patients in postural changed from supine to upright. (2)After HD, the low, high frequency power and low/high ratio were statistically significantly (P<0.05) in postural change, relatively before HD wasn''t. Take together, these findings suggest that volume depletion in chromic renal patients during a dialysis treatment is responsible for the improvement of HRV and its spectral components.
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