title: Influence of obstructive sleep apnea on heart rate turbulence.
abstract: BACKGROUND
  Patients with obstructive sleep apnea (OSA) are at increased risk for cardiovascular disease. Increased sympathetic drive is considered as one of the underlying mechanisms. Both heart rate turbulence (HRT) and heart rate variability (HRV) are parameters to describe autonomic regulation. We investigated the influence of sleep-disordered breathing (SDB) on HRT and HRV in patients with OSA.
  
  
  METHODS
  Sixty-five patients underwent overnight polysomnography for clinically suspected SDB and simultaneous Holter monitoring (11 p.m.-6 a.m.). Patients with diabetes mellitus, a history of cardiac disease, left ventricular dysfunction, periodic breathing pattern, and those on beta-blockers or theophylline were excluded. According to the apnea-hypopnea index (AHI), the patients were assigned to group A (AHI <20, n = 31) or group B (AHI > or =20, n = 34). HRV (time domain, frequency domain) and HRT (onset, slope) were then related to the severity of SDB.
  
  
  RESULTS
  Nighttime turbulence slope (TS) correlated inversely with the AHI (r = -0.45, p = 0.01) and was significantly lower in group B (8.9 +/- 1.6 ms/R-R interval) compared with that in group A (19.8 +/- 4.0 ms/R-R interval, P = 0.01). This relationship remained stable after adjusting TS for the number of ventricular premature contractions. No significant differences in turbulence onset or parameters of nighttime HRV were observed.
  
  
  CONCLUSIONS
  Alterations in nighttime HRT correlate with the severity of SDB, indicating abnormalities in cardiac autonomic activity in moderate-to-severe OSA even in the absence of overt cardiac disease. These changes may be associated with the subsequent development of cardiovascular disease.
authors.affiliation: Department of Medicine II, University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany. alexander.yang@web.de
authors.forename: A
authors.initials: A
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Schäfer
authors.forename: R
authors.initials: R
authors.lastname: Manka
authors.forename: R
authors.initials: R
authors.lastname: Andrié
authors.forename: J O
authors.initials: JO
authors.lastname: Schwab
authors.forename: T
authors.initials: T
authors.lastname: Lewalter
authors.forename: B
authors.initials: B
authors.lastname: Lüderitz
authors.forename: S
authors.initials: S
authors.lastname: Tasci
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*; D016277:Ventricular Function, Left