Background: Patients with end-stage renal disease (ESRD) undergoing hemodialysis are susceptible to the development of autonomic dysfunction, which is associated with an increased risk of sudden death. Experimental and clinical evidence suggest a crucial role of autonomic dysfunction for both, the progression of renal disease and for the high rate of cardiovascular events in these patients. In the present study, we evaluated the heart rate variability (HRV), the blood pressure variability (BPV) and the baroreflex sensitivity (BRS) in ESRD patients undergoing hemodialysis and normal controls.
Methods: Nine ESRD patients undergoing hemodialysis (mean age 53.4±10.2 years, 4 male) and nine age-matched healthy controls (mean age 52.8±10.2 years, 4 male) were assessed. Non−invasive curves of blood pressure (BP) were recorded continuously (Finometer ®) for 10 minutes, at rest, in the supine position. The heart rate variability (HRV) and systolic blood pressure variability (BPV) were estimated in the time and frequency domain (spectral analysis). The BRS was quantified by alpha index. Statistical analyzes were performed by Student's t test and the results were expressed as mean ± standard deviation.
Results: ESRD patients presented lower HRV in time domain than healthy controls (SDNN: 25.8±10.7 vs. 44.6±11.7 ms, p<0.01; VAR NN: 768.3±607.4 vs. 2113.9±1261.6 ms2, p=0.01). All frequency domain analyzed indexes, i.e., total power (361.9±297.0 vs. 1227.2±696.3 ms2,p<0.01), high-frequency (181.8±128.7 vs. 358.7±179.8 ms2, p=0.047), low-frequency (55.1±44.2 vs. 444.6±389.9 ms2, p=0.02) and very-low-frequency (72.5±75.1 vs. 279.2±119.5 ms2, p<0.01) of HRV were lower in ESRD patients. The BPV was higher in ESRD patients when compared to controls (VAR PAS: 98.4±72.0 vs. 35.4±21.4 ms2, p=0.03) and BRS was lower in ESRD patients (alpha index: 4.34±3.05 vs. 7.56±2.50 ms/mmHg, p<0.02).
Conclusion: ESRD patients undergoing hemodialysis presents reduced HRV, increase in BPV and reduced baroreflex sensitivity. These impairments may be associated with mortality in ESRD.