title: The pure effects of obstructive sleep apnea syndrome on cardiac autonomic functions: heart rate turbulence analysis.
abstract: OBJECTIVE
  To demonstrate the pure effect of obstructive sleep apnea syndrome (OSAS) on cardiac autonomic function (CAF) using heart rate turbulence (HRT) parameters.
  
  
  METHODS
  A total of 64 patients with OSAS and 30 age- and gender-matched healthy subjects were enrolled. All subjects had normal coronary arteries and were free from diabetes mellitus (DM) and hypertension (HT). The HRT parameters (TO, turbulence onset; TS, turbulence slope) were obtained from 24-h ambulatory electrocardiogram (ECG) recordings. HRT parameters were compared between groups, and the relationship between HRT and the apnea-hypopnea index (AHI) was examined.
  
  
  RESULTS
  No between-group differences were found in age or gender. Mean TO was significantly higher in the OSAS group than in healthy controls (0.89 ± 0.5, -0.08 ± 0.26; p < 0.001; respectively). The mean TS did not differ between the two groups (2.81 ± 3.06 versus 3.14 ± 2.33; p = 0.212). The AHI was positively correlated with TO (r = 0.845, p < 0.001). The multiple logistic regression analysis revealed that after adjustment for other variables, TO was a significant and independent predictor of AHI, OR 2.394 (95% CI: 1.596-3.591).
  
  
  CONCLUSIONS
  HRT (TO in particular) is correlated with AHI. Thus, impaired HRT may be an important factor underlying the occurrence of arrhythmia and sudden cardiac death in patients with OSAS.
authors.affiliation: Department of Cardiology, Faculty of Medicine, Abant Izzet Baysal University, Bolu, Turkey. cardiology14@gmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Erdem
authors.forename: O T
authors.initials: OT
authors.lastname: Dogan
authors.forename: O C
authors.initials: OC
authors.lastname: Yontar
authors.forename: K
authors.initials: K
authors.lastname: Epozturk
authors.forename: M F
authors.initials: MF
authors.lastname: Ozlu
authors.forename: S
authors.initials: S
authors.lastname: Ozturk
authors.forename: S S
authors.initials: SS
authors.lastname: Ayhan
authors.forename: F H
authors.initials: FH
authors.lastname: Erdem
authors.forename: M
authors.initials: M
authors.lastname: Yazici
authors.forename: I
authors.initials: I
authors.lastname: Akkurt
authors.forename: F
authors.initials: F
authors.lastname: Talay
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000503:physiopathology*; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology*