title: Cardiovascular autonomic regulation in patients with 3243A > G mitochondrial DNA mutation.
abstract: BACKGROUND
  Patients with the 3243A > G mutation in mitochondrial DNA (mtDNA) have an increased risk for cardiovascular morbidity and mortality. The function of the autonomic nervous system has not been evaluated in these patients.
  
  
  METHODS
  Indices of 24-hour heart rate variability (HRV) and baroreflex sensitivity (BRS) were measured in 28 patients with 3243A > G. The results were compared to controls matched with respect to age, sex, the presence of hypertension and diabetes mellitus and the use of cardiac medication. Conventional time and spectral domain indices and fractal correlation properties of HRV were analysed.
  
  
  RESULTS
  In spectral analysis of HRV, the ultra-low and very-low-frequency spectral components were lower in the patients than the controls (P < 0.05 for both). Furthermore, the short-term fractal scaling exponent was lower in the patients with 3243A > G compared to the controls (1.16 +/- 0.18 versus 1.28 +/- 0.13, P < 0.01). No significant associations were found between the HRV indices and the other characteristics of the patients with 3243A > G, such as the presence of diabetes or left ventricular hypertrophy, left ventricular systolic function, the severity of the disease or the degree of 3243A > G heteroplasmy.
  
  
  CONCLUSIONS
  Patients with the 3243A > G mutation in mtDNA have abnormalities in the spectral and fractal characteristics of HRV suggesting altered cardiac autonomic regulation. The abnormalities are not clearly associated with clinical manifestations related to 3243A > G suggesting that mitochondrial dysfunction may affect the autonomic regulatory systems more directly.
authors.affiliation: Department of Internal Medicine, University of Oulu, Finland. kirsi.majamaa-voltti@ppshp.fi
authors.forename: Kirsi
authors.initials: K
authors.lastname: Majamaa-Voltti
authors.forename: Kari
authors.initials: K
authors.lastname: Majamaa
authors.forename: Keijo
authors.initials: K
authors.lastname: Peuhkurinen
authors.forename: Timo H
authors.initials: TH
authors.lastname: Mäkikallio
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology; D002318:Cardiovascular Diseases / Q000235:genetics* / Q000503:physiopathology; D016022:Case-Control Studies; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D006801:Humans; D008297:Male; D009154:Mutation
chemical_list: D004272:DNA, Mitochondrial