title: Changes in heart rate variability after adenotonsillectomy in children with obstructive sleep apnea.
abstract: BACKGROUND
  Obstructive sleep apnea syndrome (OSAS) is associated with cardiovascular morbidity and mortality, and increased sympathetic activity is considered to be a causative link in this association. Higher levels of sympathetic activity have been reported in children with OSAS. Sympathetic predominance is indicated on heart rate variability (HRV) analysis by increased heart rate (HR) and a higher ratio of low-frequency to high-frequency band power (LF/HF). Improvement in OSAS after adenotonsillectomy (AT) in children with OSAS could, therefore, be associated with reduced HR and reduced LF/HF.
  
  
  METHODS
  Changes in HR and time and frequency components of HRV were retrospectively analyzed in 2-min epochs free of respiratory events during light, deep, and rapid-eye-movement (REM) sleep in children with OSAS who underwent polysomnography before and after AT.
  
  
  RESULTS
  Eighteen children with OSAS, aged 4.9 ± 2.4 years (mean ± SD) were studied. After AT, the apnea-hypopnea index decreased from 31.9 ± 24.8 events/h to 4.1 ± 3.7 events/h. The HR decreased after AT in all stages of sleep (99.8 ± 16.9 beats/min to 80.7 ± 12.9 beats/min [light sleep]; 100.2 ± 15.4 beats/min to 80.5 ± 12.4 beats/min [deep sleep)]; and 106.9 ± 16.4 beats/min to 87.0 ± 12.1 beats/min [REM sleep]), as did the LF/HF (1.6 ± 2.7 to 0.6 ± 0.5 [light sleep]; 1.2 ± 1.6 to 0.5 ± 0.6 [deep sleep]; and 3.0 ± 5.4 to 1.4 ± 1.7 [REM sleep]).
  
  
  CONCLUSIONS
  The proportion of sympathetic activity of the autonomic nervous system declines in children with OSAS after AT in association with improvement in sleep-disordered breathing.
authors.affiliation: Division of Respiratory and Sleep Medicine, Bronx, NY; Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Hiren V
authors.initials: HV
authors.lastname: Muzumdar
authors.affiliation: Division of Respiratory and Sleep Medicine, Bronx, NY; Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Sanghun
authors.initials: S
authors.lastname: Sin
authors.affiliation: Division of Respiratory and Sleep Medicine, Bronx, NY.
authors.forename: Margarita
authors.initials: M
authors.lastname: Nikova
authors.affiliation: Division of Cardiology, Children's Hospital at Montefiore, Bronx, NY; Albert Einstein College of Medicine, Bronx, NY.
authors.forename: Gregory
authors.initials: G
authors.lastname: Gates
authors.affiliation: Department of Biomedical Engineering, College of Health Science, Yonsei University, Seoul, South Korea.
authors.forename: Dongyoun
authors.initials: D
authors.lastname: Kim
authors.affiliation: Division of Respiratory and Sleep Medicine, Bronx, NY; Albert Einstein College of Medicine, Bronx, NY. Electronic address: rarens@montefiore.org.
authors.forename: Raanan
authors.initials: R
authors.lastname: Arens
mesh_terms: D000233:Adenoidectomy; D000234:Adenoids / Q000473:pathology / Q000601:surgery; D002675:Child, Preschool; D005260:Female; D006339:Heart Rate; D006801:Humans; D006984:Hypertrophy / Q000150:complications / Q000601:surgery; D008297:Male; D014066:Palatine Tonsil / Q000473:pathology / Q000601:surgery; D012189:Retrospective Studies; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology*; D014068:Tonsillectomy