title: Cardiac autonomic dysfunction in obese normotensive children and adolescents.
abstract: OBJECTIVE
  To test the hypothesis that obese normotensive children and adolescents present impaired cardiac autonomic control compared to non-obese normotensive ones.
  
  
  METHODS
  For this cross-sectional study, 66 children and adolescents were divided into the following groups: Obese (n=31, 12±3 years old) and Non-Obese (n=35, 13±3 years old). Obesity was defined as body mass index greater than the 95th percentile for age and gender. Blood pressure was measured by oscillometric method after 15 minutes of rest in supine position. The heart rate was continuously registered during ten minutes in the supine position with spontaneous breathing. The cardiac autonomic control was assessed by heart rate variability, which was calculated from the five-minute minor variance of the signal. The derivations were the index that indicates the proportion of the number of times in which normal adjacent R-R intervals present differences >50 miliseconds (pNN50), for the time domain, and, for the spectral analysis, low (LF) and high frequency (HF) bands, besides the low and high frequencies ratio (LF/HF). The results were expressed as mean±standard deviation and compared by Student's t-test or Mann-Whitney's U-test.
  
  
  RESULTS
  Systolic blood pressure (116±14 versus 114±13mmHg, p=0.693) and diastolic blood pressure (59±8 versus 60±11mmHg, p=0.458) were similar between the Obese and Non-Obese groups. The pNN50 index (29±21 versus 43±23, p=0.015) and HF band (54±20 versus 64±14 normalized units - n.u., p=0.023) were lower in the Obese Group. The LF band (46±20 versus 36±14 n.u., p=0.023) and LF/HF ratio (1.3±1.6 versus 0.7±0.4, p=0.044) were higher in Obese Group.
  
  
  CONCLUSIONS
  Obese normotensive children and adolescents present impairment of cardiac autonomic control.
authors.affiliation: UFJF, Juiz de Fora, MG, Brasil.
authors.forename: Isabelle Magalhães G
authors.initials: IM
authors.lastname: Freitas
authors.affiliation: UFJF, Juiz de Fora, MG, Brasil.
authors.forename: Josiane Aparecida
authors.initials: JA
authors.lastname: Miranda
authors.affiliation: UFJF, Juiz de Fora, MG, Brasil.
authors.forename: Pedro Augusto C
authors.initials: PA
authors.lastname: Mira
authors.affiliation: UFJF, Juiz de Fora, MG, Brasil.
authors.forename: Carla Marcia M
authors.initials: CM
authors.lastname: Lanna
authors.affiliation: UFJF, Juiz de Fora, MG, Brasil.
authors.forename: Jorge Roberto P
authors.initials: JR
authors.lastname: Lima
authors.affiliation: UFJF, Juiz de Fora, MG, Brasil.
authors.forename: Mateus Camaroti
authors.initials: MC
authors.lastname: Laterza
mesh_terms: D000293:Adolescent; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001794:Blood Pressure; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008297:Male; D063766:Pediatric Obesity / Q000503:physiopathology*; D012016:Reference Values