title: Assessment of autonomic nerve function in acute intermittent porphyria; a study based on spectral analysis of heart rate variability.
abstract: OBJECTIVE
  To assess the function of the autonomic nervous system in patients with acute intermittent porphyria by spectral analysis of the heart rate variability.
  
  
  METHODS
  A cross-sectional case-control study.
  
  
  METHODS
  Patients were examined at the Primary Health Care Centre, Arjeplog and at Umeå University Hospital, where the controls were also examined.
  
  
  METHODS
  Twenty-three patients with acute intermittent porphyria verified by DNA analysis and 92 healthy controls were included.
  
  
  METHODS
  The mid-frequency band power after tilting was used to evaluate sympathetic function, and the high frequency band power during controlled breathing at 12 breaths min-1 and the mid-frequency band power during controlled deep breathing at 6 breaths min-1 were used to evaluate parasympathetic function.
  
  
  RESULTS
  There was no evidence of sympathetic dysfunction in the patients. The mid-frequency band power during controlled deep breathing at 6 breaths min-1 was significantly (P = 0.02) lower in the patient group.
  
  
  CONCLUSIONS
  Our findings indicate a parasympathetic dysfunction in patients with acute intermittent porphyria. This may be causally related to sudden cardiac death and the life-threatening arrhythmias which have been observed in this disorder.
authors.affiliation: Department of Internal Medicine, Umeå University Hospital, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Blom
authors.forename: C
authors.initials: C
authors.lastname: Andersson
authors.forename: B O
authors.initials: BO
authors.lastname: Olofsson
authors.forename: P
authors.initials: P
authors.lastname: Bjerle
authors.forename: U
authors.initials: U
authors.lastname: Wiklund
authors.forename: F
authors.initials: F
authors.lastname: Lithner
mesh_terms: D000328:Adult; D000368:Aged; D001341:Autonomic Nervous System / Q000503:physiopathology; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D017118:Porphyria, Acute Intermittent / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted