title: Cardiovascular Autonomic Dysfunction in Patients with Morbid Obesity.
abstract: BACKGROUND
  Morbid obesity is directly related to deterioration in cardiorespiratory capacity, including changes in cardiovascular autonomic modulation.
  
  
  OBJECTIVE
  This study aimed to assess the cardiovascular autonomic function in morbidly obese individuals.
  
  
  METHODS
  Cross-sectional study, including two groups of participants: Group I, composed by 50 morbidly obese subjects, and Group II, composed by 30 nonobese subjects. The autonomic function was assessed by heart rate variability in the time domain (standard deviation of all normal RR intervals [SDNN]; standard deviation of the normal R-R intervals [SDNN]; square root of the mean squared differences of successive R-R intervals [RMSSD]; and the percentage of interval differences of successive R-R intervals greater than 50 milliseconds [pNN50] than the adjacent interval), and in the frequency domain (high frequency [HF]; low frequency [LF]: integration of power spectral density function in high frequency and low frequency ranges respectively). Between-group comparisons were performed by the Student's t-test, with a level of significance of 5%.
  
  
  RESULTS
  Obese subjects had lower values of SDNN (40.0 ± 18.0 ms vs. 70.0 ± 27.8 ms; p = 0.0004), RMSSD (23.7 ± 13.0 ms vs. 40.3 ± 22.4 ms; p = 0.0030), pNN50 (14.8 ± 10.4 % vs. 25.9 ± 7.2%; p = 0.0061) and HF (30.0 ± 17.5 Hz vs. 51.7 ± 25.5 Hz; p = 0.0023) than controls. Mean LF/HF ratio was higher in Group I (5.0 ± 2.8 vs. 1.0 ± 0.9; p = 0.0189), indicating changes in the sympathovagal balance. No statistical difference in LF was observed between Group I and Group II (50.1 ± 30.2 Hz vs. 40.9 ± 23.9 Hz; p = 0.9013).
  
  
  CONCLUSIONS
  morbidly obese individuals have increased sympathetic activity and reduced parasympathetic activity, featuring cardiovascular autonomic dysfunction.
authors.affiliation: Programa de Tratamento Multidisciplinar da Obesidade, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Maurício de
authors.initials: Md
authors.lastname: Sant Anna Junior
authors.affiliation: Programa de Tratamento Multidisciplinar da Obesidade, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: João Regis Ivar
authors.initials: JR
authors.lastname: Carneiro
authors.affiliation: Programa de Tratamento Multidisciplinar da Obesidade, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Renata Ferreira
authors.initials: RF
authors.lastname: Carvalhal
authors.affiliation: Programa de Tratamento Multidisciplinar da Obesidade, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Diego de Faria Magalhães
authors.initials: Dde F
authors.lastname: Torres
authors.affiliation: Programa de Tratamento Multidisciplinar da Obesidade, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Gustavo Gavina da
authors.initials: GG
authors.lastname: Cruz
authors.affiliation: Programa de Tratamento Multidisciplinar da Obesidade, Hospital Universitário Clementino Fraga Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: José Carlos do Vale
authors.initials: JC
authors.lastname: Quaresma
authors.affiliation: Divisão de Nefrologia, Faculdade de Medicina, Universidade Federal Fluminense, Niterói, RJ, Brazil.
authors.forename: Jocemir Ronaldo
authors.initials: JR
authors.lastname: Lugon
authors.affiliation: Departamento de Fisioterapia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Fernando Silva
authors.initials: FS
authors.lastname: Guimarães
mesh_terms: D000328:Adult; D000886:Anthropometry; D001342:Autonomic Nervous System Diseases / Q000209:etiology / Q000503:physiopathology*; D002318:Cardiovascular Diseases / Q000209:etiology / Q000503:physiopathology*; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength / Q000502:physiology; D009767:Obesity, Morbid / Q000150:complications / Q000503:physiopathology*; D011237:Predictive Value of Tests; D012016:Reference Values; D012129:Respiratory Function Tests; D012132:Respiratory Muscles / Q000503:physiopathology; D012307:Risk Factors; D018709:Statistics, Nonparametric; D055815:Young Adult