Effect of hemodialysis on cardiovascular rhythms in end-stage renal failure

The purpose of this investigation was to determine non-invasively the alteration in autonomic cardiovascular control observed in end-stage renal disease (ESRD) patients submitted to a hemodialysis (HD) treatment. The effect of HD on finger blood pressure (BP) and heart rate (HR) variability was studied by means of spectral analysis in 12 ESRD patients at supine and during 45 degrees head-up tilt. Amplitude spectra of BP and HR rhythmicity were estimated and integrated amplitudes of the low (60 to 140 mHz, Mayer waves) and high frequency (area under the curve at mean respiration rate +/- 50 mHz) components were computed. The overall variability of a signal was given by the total area under the curve of the spectrum between 20 and 500 mHz. The transfer function was calculated between systolic BP and HR fluctuations using cross-spectral analysis. The principle findings are as follows: (1) Before HD, overall variability in systolic and diastolic BP as well as in the low frequency component in BP spectra were markedly reduced in ESRD patients compared to control subjects. Dialysis produced an immediate improvement in overall BP variability and the LF BP rhythmicity. (2) Before HD, there was an alteration of the HR spectral profile in uremic patients. (3) Chronic uremia and HD induced no changes in the transfer gain characteristic of modulation of HR by systolic BP. Taken together, these findings suggest that volume depletion in ESRD patients during a dialysis treatment is responsible for the improvement of overall BP variability and its spectral components.