title: Baroreflex resetting after successful surgical repair of tetralogy of Fallot.
abstract: BACKGROUND
  Tetralogy of Fallot (TOF) and its surgical repair are associated with alterations in right ventricular systolic and diastolic functions. The cardiopulmonary baroreflex describes the peripheral vasoconstriction response to the volume-unloading deactivation of left and possibly right ventricular receptors. Alterations in cardiac geometry or distensibility and pulmonary vasculature of operated TOF may affect the mechanical stimulation of sensitive cardiopulmonary receptors leading to an impaired baroreflex function. There has to date been no report on the integrity of baroreflex function in postoperative TOF.
  
  
  OBJECTIVE
  To characterize the combined cardiopulmonary and baroreflex response of patients successfully operated for TOF in early childhood to central volume unloading using graded lower body negative pressure (LBNP) application.
  
  
  METHODS
  Fifteen patients operated on for TOF (mean+/-SEM) 15.7+/-1.4 years previously and 13 healthy age-matched control subjects were submitted to four consecutive 5 min LBNP applications at -10, -20, -30 and -40 mmHg. Forearm blood flow and vascular resistance, left ventricle end-diastolic diameter (LVEDD), arterial blood pressure and heart rate were obtained.
  
  
  RESULTS
  TOF exhibited a lower LVEDD (42.7+/-1.5 mm) than control subjects (51.9+/-1.6). The forearm vascular resistance to LVEDD relationship was shifted left and upward in TOF compared with that of control subjects, but the slope of the relationship was not different between groups. LBNP -40 mmHg induced a lesser change in heart rate in TOF (+10.6+/-1.5%) than in control subjects (+14.7 +/-2.4%) and an increase (P<0.05) in diastolic blood pressure in TOF (-2.4+/-2.5%), which was not seen in control subjects (+4.3+/-2.9%).
  
  
  CONCLUSIONS
  Young adults successfully operated on for TOF in early childhood exhibit a resetting of the cardiopulmonary baroreflex to operate at smaller LVEDD and at a higher level of forearm vascular resistance. The blunted heart rate response to LBNP -40 mmHg is consistent with previous observations pointing to disturbances in the efferent arm of the baroreflex.
authors.affiliation: Department of Kinesiology and Physical Education, McGill University, Montréal, Québec. helene.perrault@mcgill.ca
authors.forename: Hélène
authors.initials: H
authors.lastname: Perrault
authors.forename: Dominique
authors.initials: D
authors.lastname: Johnson
authors.forename: N'Guessan
authors.initials: N
authors.lastname: Kouamé
authors.forename: Alain
authors.initials: A
authors.lastname: Cloutier
authors.forename: André
authors.initials: A
authors.lastname: Davignon
authors.forename: Claude
authors.initials: C
authors.lastname: Chartrand
authors.forename: Jean
authors.initials: J
authors.lastname: Cléroux
mesh_terms: D000293:Adolescent; D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D013504:Cardiovascular Surgical Procedures; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D011311:Pressoreceptors / Q000503:physiopathology; D011652:Pulmonary Circulation / Q000502:physiology*; D013771:Tetralogy of Fallot / Q000503:physiopathology* / Q000601:surgery*; D016896:Treatment Outcome