title: Menopause, hormone replacement and RR and QT modulation during sleep.
abstract: OBJECTIVE
  Sleep affects the RR interval in electrocardiogram (ECG) recordings and ventricular repolarization differentially in men and women. Compared to men, pre-menopausal women have a more pronounced shortening of RR interval and prolongation of QT and QT corrected (QTc, by Bazett's formula) ECG waves during rapid eye movement (REM) sleep. The aim of the present study was to evaluate sleep-related RR and QT changes: (1) with the physiological decline in female hormones occurring with menopause, and (2) after hormone replacement therapy with estrogen and progesterone (HRT).
  
  
  METHODS
  We analyzed ECG recordings from 14 post-menopausal women (48-61 years old) who underwent polysomnography before HRT (T1) and after 6 months of HRT (T2) with estrogen and progesterone. Eight of the post-menopausal women (48-54 years) were also compared to eight age-matched pre-menopausal women. In all subjects, mean RR interval, mean QT interval and QTc, were obtained from 1-min recordings selected from wakefulness, stage 2 and REM sleep.
  
  
  RESULTS
  Pre-menopausal and post-menopausal women showed similar changes in RR, QT and QTc intervals from wakefulness through sleep. Specifically, in both pre-menopausal and post-menopausal women the RR interval was shorter during REM sleep compared to wakefulness (P=0.009) and stage 2 sleep (P=0.001); the QT interval was more prolonged during stage 2 (P=0.002) and REM (P=0.006); and the QTc interval was significantly prolonged during stage 2 (P=0.01) and REM (P=0.0003) sleep compared to wakefulness. Among post-menopausal women, both before and after HRT (T1 and T2), RR interval shortened significantly during REM compared to wakefulness (P=0.03) and to stage 2 (P=0.002); the absolute QT interval was longer during stage 2, compared to both wakefulness (P<0.001) and REM (P<0.001); the QTc interval was increased during REM sleep compared to wakefulness (P=0.003).
  
  
  CONCLUSIONS
  Sleep-related RR and QT changes in women are not altered by menopausal status nor by post-menopausal hormonal replacement with estrogen and progesterone.
authors.affiliation: Centre de Recherche, Hôpital du Sacré-Coeur de Montréal, 5400 boul. Gouin Ouest, Montréal, Que., Canada H4J 1C5. paola-lanfranchi@crhsc.umontreal.ca
authors.forename: Paola A
authors.initials: PA
authors.lastname: Lanfranchi
authors.forename: Nadia
authors.initials: N
authors.lastname: Gosselin
authors.forename: Tomas
authors.initials: T
authors.lastname: Kara
authors.forename: Pavel
authors.initials: P
authors.lastname: Jurak
authors.forename: Virend K
authors.initials: VK
authors.lastname: Somers
authors.forename: Régine
authors.initials: R
authors.lastname: Denesle
authors.forename: Dominique
authors.initials: D
authors.lastname: Petit
authors.forename: Julie
authors.initials: J
authors.lastname: Carrier
authors.forename: Réginald
authors.initials: R
authors.lastname: Nadeau
authors.forename: Jacques
authors.initials: J
authors.lastname: Montplaisir
mesh_terms: D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D004562:Electrocardiography; D015914:Estrogen Replacement Therapy; D005260:Female; D006329:Heart Conduction System / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D017286:Polysomnography; D017698:Postmenopause / Q000502:physiology*; D017697:Premenopause / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology*