Blood Pressure and Heart Rate Variability in Patients on Conventional or Sodium-Profiling Hemodialysis

Abstract

Background. Autonomic nervous system dysfunction and dialysate sodium (Na) concentration are believed to play a role in the pathogenesis of hemodialysis-related hypertension. The present study was undertaken to determine whether increases in blood pressure in hemodialysis patients are associated with changes in heart rate variability (HRV), a measure of the autonomic nervous system function, and long-term exposure to increased dialysate Na concentration. Methods. Baseline clinical, biochemical data and HRV of patients undergoing increased Na profiling dialysis (High-Na, n = 9) and on conventional treatment (Control, n = 11) were compared with those obtained after one year of study. Results. After one year, the mean predialysis systolic blood pressure (SBP) increased in seven patients of the High-Na and in five of the Control group, and decreased or remained unchanged in the remaining subjects. Initial HRV was significantly higher in patients with increased SBP, and it increased further in these patients after one year. At the end of the study, post-dialysis plasma Na, osmolality, and weight gains were significantly higher in the High-Na group. No significant correlation, however, was found between individual changes in intradialytic sodium elimination and the alterations in blood pressure. Conclusion. These data suggest that the dialysate sodium concentration, a most important determinant of interdialytic weight gain and fluid balance, is only partly correlated with long-term changes in blood pressure. An increased blood pressure over time may develop in a subset of hemodialysis patients with higher HRV, suggestive of increased sympathetic activity.