title: Long-term changes in heart rate variability in elementary school-aged children with sleep-disordered breathing.
abstract: OBJECTIVE
  Sleep-disordered breathing (SDB) in adults and children has been associated with reduced heart rate variability (HRV) indicative of autonomic dysfunction, which in turn is associated with an increased risk for cardiovascular morbidity. However, the long-term effects of pediatric SDB that has either resolved or remains unresolved on HRV are unknown.
  
  
  METHODS
  Forty Children with previously diagnosed SDB and 20 non snoring controls underwent repeat overnight polysomnography (PSG) four years after the original diagnosis. At follow-up, children aged 11 to 16 years were categorized into resolved (absence of snoring and obstructive apnea hypopnea index [OAHI]≤1) or unresolved (continued to snore or had an OAHI>1) groups. HRV was assessed using power spectral analysis for each sleep stage.
  
  
  RESULTS
  There were no group differences in age, sex or body mass index (BMI) z score. Both the resolved and unresolved SDB groups showed significant improvement in OAHI. The control, resolved, and unresolved groups all showed a significant reduction in total power (P<.001), low-frequency (LF) power (P<.05), high-frequency (HF) power (P<.001), and an increase in the LF/HF ratio (P<.001) from baseline to follow-up in all sleep stages.
  
  
  CONCLUSIONS
  HRV did not differ between non snoring children and children with resolved and unresolved SDB four years after initial diagnosis, concomitant with a significant reduction in OAHI in both SDB groups. All groups demonstrated a decrease in HRV from baseline to follow-up which may reflect an age-related phenomenon in these children.
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia.
authors.forename: Anna
authors.initials: A
authors.lastname: Vlahandonis
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia.
authors.forename: Stephanie R
authors.initials: SR
authors.lastname: Yiallourou
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia; Division of Sleep Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Sands
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia; Melbourne Children's Sleep Centre, Monash Children's Programme, Monash Medical Centre, Melbourne, Australia.
authors.forename: Gillian M
authors.initials: GM
authors.lastname: Nixon
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia; Melbourne Children's Sleep Centre, Monash Children's Programme, Monash Medical Centre, Melbourne, Australia.
authors.forename: Margot J
authors.initials: MJ
authors.lastname: Davey
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Walter
authors.affiliation: The Ritchie Centre, Monash Institute of Medical Research, Monash University, Melbourne, Australia. Electronic address: rosemary.horne@monash.edu.
authors.forename: Rosemary S C
authors.initials: RS
authors.lastname: Horne
mesh_terms: D000293:Adolescent; D001341:Autonomic Nervous System / Q000503:physiopathology; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology*; D001794:Blood Pressure / Q000502:physiology; D002648:Child; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D017286:Polysomnography; D011446:Prospective Studies; D015656:Respiratory Mechanics / Q000502:physiology; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology; D012913:Snoring / Q000503:physiopathology
keywords: Autonomic dysfunction; Follow-up; Heart rate variability; Pediatric; Sleep disordered breathing; Treatment