title: Preserved autonomic heart rate modulation in chronic renal failure patients in response to hemodialysis and orthostatism.
abstract: BACKGROUND
  The aim of this work was to measure the impact of active orthostatism and hemodialysis (HD) upon heart rate variability (HRV) in chronic renal failure (CRF) patients before and after HD.
  
  
  METHODS
  Nineteen healthy subjects (age 27 ± 8 years old, 13 were female) and 19 unmedicated CRF patients with HD thrice per week (average HD vintage = 12 months, age 32 ± 9 years old, 11 were female) were included. Five-minute length HRV time series were obtained during supine position and orthostatism. Recordings from CRF patients were obtained before and after HD. Time domain and frequency domain HRV indexes were compared by analysis of variance. The correlation between each HRV index and change in sympathetic weighting induced by different maneuvers was tested by Kendall's Tau correlation. A p value <0.05 was considered statistically significant.
  
  
  RESULTS
  HRV indexes which are associated with sympathetic activity increased in response to orthostatism in the healthy group, e.g., low-frequency to high-frequency (LF/HF) ratio, Ln (LF/HF) = -0.3 ± 0.9 versus 0.9 ± 0.9. CRF patients before HD had higher sympathetic weighting than healthy participants, even in supine position, Ln (LF/HF) = 0.6 ± 1.0, but such a difference was accentuated during orthostatism, Ln (LF/HF) = 1.5 ± 1.0, and after HD: Ln (LF/HF) = 0.8 ± 1.3 (supine position) and 2.5 ± 2.1 (orthostatism). All HRV indexes were associated with increments in sympathetic weighting between maneuvers (Kendall's correlations absolute values ≥ 0.24).
  
  
  CONCLUSIONS
  Unmedicated young CRF patients treated with hemodynamically stable maintenance HD showed preserved capacity of autonomic response (with gradual sympathetic increases) induced by cardiovascular challenges such as orthostatism and HD.
authors.affiliation: Departamento de Instrumentación Electromecánica, Instituto Nacional de Cardiología Ignacio Chávez, C. Juan Badiano No. 1 Col. Sección XVI. Tlalpan, CP 14080, Mexico, D.F., Mexico.
authors.forename: Claudia
authors.initials: C
authors.lastname: Lerma
authors.forename: Hortensia
authors.initials: H
authors.lastname: González
authors.forename: Hector
authors.initials: H
authors.lastname: Pérez-Grovas
authors.forename: Marco V
authors.initials: MV
authors.lastname: José
authors.forename: Oscar
authors.initials: O
authors.lastname: Infante
mesh_terms: D000328:Adult; D001794:Blood Pressure; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007676:Kidney Failure, Chronic / Q000503:physiopathology* / Q000628:therapy*; D008297:Male; D011187:Posture / Q000502:physiology*; D006435:Renal Dialysis; D016683:Supine Position / Q000502:physiology; D013564:Sympathetic Nervous System / Q000503:physiopathology; D055815:Young Adult