title: Determinants and functional impact of restrictive physiology after repair of tetralogy of Fallot: new insights from magnetic resonance imaging.
abstract: BACKGROUND
  The presence of end-diastolic forward flow (EDFF) in the pulmonary arteries is commonly regarded as a hallmark of restrictive physiology of the right ventricle (RV) which, in turn, has been associated with a better long-term prognosis in patients after TOF repair. However, controversy persists over the beneficial clinical consequences of restrictive physiology. We aimed at determining the clinical relevance of restrictive physiology late after TOF repair.
  
  
  METHODS
  Fifty magnetic resonance examinations of 50 patients (age 13.0 ± 2.8 years, 26 males) with repaired TOF were evaluated. The patients were divided into: Group-1 with and Group-2 without EDFF; Group-A with smaller RVs (<170 ml/m2) and Group-B with larger RVs (≥ 170 ml/m2). Maximum oxygen consumption as percent of predicted (VO2max-pred) at a recent exercise test was recorded.
  
  
  RESULTS
  Groups-1 and 2 did not differ with regard to their right ventricular end-diastolic volume, pulmonary regurgitant volume, or QRS duration. Patients in Group-1 had a higher VO2max-pred than patients in Group-2 (70.3% versus 54.7% of predicted, p<0.01). In Group-1A versus 2A (RV<170 ml/m(2), with and without EDFF) this difference persisted, but in Group B there was no difference in VO2max-pred between patients with and without EDFF. The flow volume of EDFF correlated with VO2max-pred (r=0.444, p=0.007).
  
  
  CONCLUSIONS
  End-diastolic forward flow measured by magnetic resonance is present in patients with small and large RVs. The presence of EDFF is associated with better exercise tolerance, but only in patients with relatively small RVs.
authors.affiliation: Department of Diagnostic Imaging, The Hospital for Sick Children, University of Toronto, Canada.
authors.forename: Whal
authors.initials: W
authors.lastname: Lee
authors.forename: Shi-Joon
authors.initials: SJ
authors.lastname: Yoo
authors.forename: Susan L
authors.initials: SL
authors.lastname: Roche
authors.forename: Paul
authors.initials: P
authors.lastname: Kantor
authors.forename: Glen
authors.initials: G
authors.lastname: van Arsdell
authors.forename: Eun-Ah
authors.initials: EA
authors.lastname: Park
authors.forename: Andrew
authors.initials: A
authors.lastname: Redington
authors.forename: Lars
authors.initials: L
authors.lastname: Grosse-Wortmann
mesh_terms: D000293:Adolescent; D002648:Child; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000639:trends*; D008297:Male; D012189:Retrospective Studies; D013771:Tetralogy of Fallot / Q000503:physiopathology* / Q000601:surgery*; D016896:Treatment Outcome; D016278:Ventricular Function, Right / Q000502:physiology*