title: Relation of right ventricular mechanics to exercise tolerance in children after tetralogy of Fallot repair.
abstract: BACKGROUND
  Progressive right ventricular (RV) dysfunction and exercise intolerance are common problems after tetralogy of Fallot (TOF) repair. We investigated RV myocardial deformation and dyssynchrony in children after TOF repair and their association with exercise capacity.
  
  
  METHODS
  Asymptomatic children after TOF repair were investigated by 2-dimensional speckle tracking echocardiography, magnetic resonance, and metabolic exercise study. Patients with RV outflow obstruction were excluded. Peak RV longitudinal strain and strain rate (SR) and dyssynchrony (RV intraventricular delay) were compared with healthy controls. Associations between RV strain, dyssynchrony, and exercise capacity were analyzed.
  
  
  RESULTS
  Thirty-nine (81%) of 48 TOF patients and 40 healthy controls had adequate RV strain imaging. The TOF patients had moderately dilated RVs and normal RV ejection fraction. Right ventricular peak systolic strain (-23.2% ± 5.1% vs -28.5% ± 8.5%, P < .001) and SR (-1.46 ± 0.68 vs -2.1 ± 0.8, P < .001) were reduced in TOF patients compared with controls. Right ventricular intraventricular delay was higher in TOF patients (146.0 ± 159 vs 71.0 ± 92 milliseconds, P = .008). Decreased RV strain and SR were associated with increased RV dyssynchrony (strain parameter estimate [PE] 6.31 [2.30], P = .007; SR [PE] 11.32 [3.84], P = .004). Increased RV-left ventricular delay was associated with prolonged QRS duration (PE 0.13 [0.058], P = .03) and reduced RV ejection fraction (PE -2.95 [1.275], P = .02). Reduced RV peak SR was associated with decreased exercise peak oxygen uptake (PE 0.14 [0.07], P = .04).
  
  
  CONCLUSIONS
  After repair of TOF, asymptomatic children have reduced RV deformation in association with RV dyssynchrony and reduced exercise tolerance.
authors.affiliation: Division of Paediatric Cardiology, The Labatt Family Heart Center, Hospital for Sick Children and University of Toronto, Toronto, Canada. mark.friedberg@sickkids.ca
authors.forename: Mark K
authors.initials: MK
authors.lastname: Friedberg
authors.forename: Fernanda P
authors.initials: FP
authors.lastname: Fernandes
authors.forename: Susan L
authors.initials: SL
authors.lastname: Roche
authors.forename: Cameron
authors.initials: C
authors.lastname: Slorach
authors.forename: Lars
authors.initials: L
authors.lastname: Grosse-Wortmann
authors.forename: Cedric
authors.initials: C
authors.lastname: Manlhiot
authors.forename: Cheryl
authors.initials: C
authors.lastname: Fackoury
authors.forename: Brian W
authors.initials: BW
authors.lastname: McCrindle
authors.forename: Luc
authors.initials: L
authors.lastname: Mertens
authors.forename: Paul F
authors.initials: PF
authors.lastname: Kantor
mesh_terms: D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D018450:Disease Progression; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013771:Tetralogy of Fallot / Q000000981:diagnostic imaging / Q000601:surgery*; D018608:Ultrasonography, Doppler / Q000379:methods; D018497:Ventricular Dysfunction, Right / Q000000981:diagnostic imaging / Q000503:physiopathology*