title: Cardiac autonomic functions in obese children.
abstract: OBJECTIVE
  The autonomic nervous system is assumed to have a role in the pathophysiology of obesity. In this study, we evaluated the autonomic system by measuring heart rate variability (HRV) in obese children.
  
  
  METHODS
  Thirty-two obese and 30 healthy children (mean ages: 11.6±2.0 years and 11.0±2.9 years, respectively) were enrolled in the study. Obesity was defined as a body mass index higher than 97th percentile for age- and gender-specific reference values. All participants were free of any disease and none of them was receiving any medication. Twenty-four-hour ambulatory electrocardiographic recordings were obtained and the time-domain and frequency-domain indices of HRV were analyzed. The study group was evaluated with respect to insulin resistance by HOMA-IR values.
  
  
  RESULTS
  A significant decrease in calculated HRV variables was observed in obese children as compared to controls. The HRV alteration was found in both time-domain and frequency-domain parameters. The subgroup analysis of the study group revealed a significant decrease in all investigated HRV parameters in the insulin-resistant obese children compared to the non-insulin-resistant obese ones.
  
  
  CONCLUSIONS
  Our results indicate that HRV is decreased in obese children, which implies parasympathetic withdrawal and sympathetic predominance. A marked decrease in HRV was observed in insulin-resistant obese children compared to their non-insulin-resistant counterparts. We propose that autonomic imbalance pertaining especially to insulin resistance may be involved in the pathogenesis of obesity in pediatric patients.
authors.affiliation: Department of Pediatrics Division of Endocrinology, Gulhane Military Medical Academy, Ankara, Turkey.
authors.forename: Mehmet Emre
authors.initials: ME
authors.lastname: Taşçılar
authors.forename: Mehmet
authors.initials: M
authors.lastname: Yokuşoğlu
authors.forename: Mehmet
authors.initials: M
authors.lastname: Boyraz
authors.forename: Oben
authors.initials: O
authors.lastname: Baysan
authors.forename: Cem
authors.initials: C
authors.lastname: Köz
authors.forename: Ruşen
authors.initials: R
authors.lastname: Dündaröz
mesh_terms: D000293:Adolescent; D001341:Autonomic Nervous System / Q000503:physiopathology*; D016022:Case-Control Studies; D002648:Child; D015716:Electrocardiography, Ambulatory; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D009765:Obesity / Q000503:physiopathology*