title: Orthostatic sympathetic derangement in subjects with fibromyalgia.
abstract: OBJECTIVE
  To assess the sympathetic-parasympathetic balance in individuals with fibromyalgia (FM), and its response to orthostatic stress, by power spectral analysis of heart rate variability.
  
  
  METHODS
  We studied 19 women with FM and 19 age matched controls. A high resolution electrocardiogram was obtained in supine and standing postures after achieving a stable heart rate. Spectral analysis of R-R intervals was done by the fast Fourier transform algorithm.
  
  
  RESULTS
  Analyses of the different frequency components revealed significant difference between the 2 groups in the low frequency (0.050-0.150 Hz) band, which reflects modulation of the sympathetic nervous system. Controls displayed an increased power spectral density upon standing (+0.081 +/- 0.217 Hz); individuals with FM had a discordant response (-0.057 +/- 0.097 Hz) (p = 0.018).
  
  
  CONCLUSIONS
  In FM, there is a deranged sympathetic response to orthostatic stress. This abnormality may have implications regarding the pathogenesis of FM.
authors.affiliation: Instituto Nacional de Cardiolagía Ignacio Chávez, Hospital Gea Gonzalez, México DF, México.
authors.forename: M
authors.initials: M
authors.lastname: Martínez-Lavín
authors.forename: A G
authors.initials: AG
authors.lastname: Hermosillo
authors.forename: C
authors.initials: C
authors.lastname: Mendoza
authors.forename: R
authors.initials: R
authors.lastname: Ortiz
authors.forename: J C
authors.initials: JC
authors.lastname: Cajigas
authors.forename: C
authors.initials: C
authors.lastname: Pineda
authors.forename: A
authors.initials: A
authors.lastname: Nava
authors.forename: M
authors.initials: M
authors.lastname: Vallejo
mesh_terms: D000328:Adult; D017704:Baroreflex; D005260:Female; D005356:Fibromyalgia / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D016683:Supine Position; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D018667:Tilt-Table Test