title: Timing of nocturnal ventricular ectopy in heart failure patients with sleep apnea.
abstract: BACKGROUND
  Ventricular ectopy is frequent in heart failure (HF) patients with sleep apnea. A previous report indicated that in HF patients, ventricular premature beats (VPB) occurred more frequently during episodes of recurrent central sleep apnea (CSA) than during normal breathing, and their frequency was greater during hyperpnea than during apnea. We hypothesized that, because respiratory stimuli that might provoke ventricular ectopy are stronger during obstructive apneas than during central apneas, in contrast to CSA, VPBs would be more frequent during apnea than hyperpnea in HF patients with obstructive sleep apnea (OSA).
  
  
  METHODS
  HF patients in sinus rhythm who have OSA or CSA (apnea-hypopnea index, > or = 15 events per hour) and with > 30 VPBs per hour were matched for severity of cardiac dysfunction and sleep apnea. The frequency of VPBs was then assessed during stage 2 sleep during the apneic and the hyperpneic phases of recurrent obstructive or central apneas.
  
  
  RESULTS
  VPBs occurred more frequently during the apneic phase than during the hyperpneic phase in patients with OSA. In contrast, VPBs occurred more frequently during the hyperpneic phase than the apneic phase in patients with CSA. There was no difference in the degree of apnea-related oxygen desaturation between central and obstructive apneas.
  
  
  CONCLUSIONS
  In patients with HF, nocturnal ventricular ectopy oscillates in time with oscillations in ventilation, with VPBs occurring predominantly during apneas in patients with OSA, but during hyperpneas in patients with CSA. This difference in VPB timing between OSA and CSA may be attributable to the differences in timing of arrhythmic stresses in these patients.
authors.affiliation: Sleep Research Laboratory, Toronto Rehabilitation Institute, Toronto, ON, Canada.
authors.forename: Clodagh M
authors.initials: CM
authors.lastname: Ryan
authors.forename: Stephen
authors.initials: S
authors.lastname: Juvet
authors.forename: Richard
authors.initials: R
authors.lastname: Leung
authors.forename: T Douglas
authors.initials: TD
authors.lastname: Bradley
mesh_terms: D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D012720:Severity of Illness Index; D020182:Sleep Apnea, Central / Q000150:complications* / Q000503:physiopathology; D020181:Sleep Apnea, Obstructive / Q000150:complications* / Q000503:physiopathology; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology; D018879:Ventricular Premature Complexes / Q000209:etiology* / Q000503:physiopathology*