title: The effect of insulin on cardiac autonomic balance predicts weight reduction after gastric bypass.
abstract: OBJECTIVE
  The aim of this study was to assess the predictive role of autonomic reactivity in body weight loss induced by gastric bypass.
  
  
  METHODS
  A group of 22 morbidly obese subjects, who were due to undergo a gastric bypass, were submitted, before surgery, to a euglycaemic-hyperinsulinaemic clamp, during which a continuous recording of the ECG was performed. The effect of insulin on cardiac autonomic balance was evaluated by performing power spectral analysis of heart rate variability. The low-to-high frequency ratio was calculated before and during the clamp and its modifications were expressed as % delta low-to-high frequency ratio (%Delta L: H).
  
  
  RESULTS
  Preoperative %Delta L: H showed a significant (p=0.0009, r2=0.43), positive relationship to the reduction of body weight, measured 1 year after surgery and expressed as % excess weight loss (% EWL). Preoperative BMI was also significantly (p=0.0009, r2=0.43) negatively related to the 12-month % EWL. In a multiple regression analysis, %Delta L: H remained a significant (p=0.003), independent predictor of body weight loss, even when preoperative BMI or age, % fat mass, insulinaemia and glucose disposal were taken into account.
  
  
  CONCLUSIONS
  The best correction of excess body weight was achieved by those obese subjects who had a preserved capacity to shift their cardiac autonomic balance towards a sympathetic prevalence in response to an euglycaemic-hyperinsulinaemic clamp. Further studies are needed to elucidate the mechanisms through which the autonomic nervous system influences weight reduction.
authors.affiliation: Service of Therapeutic Education for Chronic Disease, Geneva University Hospital, 1211, Geneva, Switzerland. Elisabetta.Harsch@hcuge.ch
authors.forename: E
authors.initials: E
authors.lastname: Bobbioni-Harsch
authors.forename: J
authors.initials: J
authors.lastname: Sztajzel
authors.forename: V
authors.initials: V
authors.lastname: Barthassat
authors.forename: T N O
authors.initials: TN
authors.lastname: Lehmann
authors.forename: K
authors.initials: K
authors.lastname: Sievert
authors.forename: G
authors.initials: G
authors.lastname: Chassot
authors.forename: O
authors.initials: O
authors.lastname: Huber
authors.forename: P
authors.initials: P
authors.lastname: Morel
authors.forename: A
authors.initials: A
authors.lastname: Golay
authors.forename: F
authors.initials: F
authors.lastname: Assimacopoulos-Jeannet
mesh_terms: D000328:Adult; D000713:Anastomosis, Roux-en-Y / Q000379:methods; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D005260:Female; D015390:Gastric Bypass / Q000379:methods*; D006329:Heart Conduction System / Q000187:drug effects*; D006801:Humans; D006946:Hyperinsulinism; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D009767:Obesity, Morbid / Q000601:surgery; D012044:Regression Analysis; D015431:Weight Loss
chemical_list: D001786:Blood Glucose; D007328:Insulin