title: Patients with repaired tetralogy of Fallot suffer from intra- and inter-ventricular cardiac dyssynchrony: a cardiac magnetic resonance study.
abstract: OBJECTIVE
  Patients with repaired tetralogy of Fallot (rTOF) frequently have right bundle branch block. To better understand the contribution of cardiac dyssynchrony to dysfunction, we developed a method to quantify left (LV), right (RV), and inter-ventricular dyssynchrony using standard cine cardiac magnetic resonance (CMR).
  
  
  RESULTS
  Thirty patients with rTOF and 17 healthy controls underwent cine CMR. Patients were imaged twice to assess inter-test reproducibility. Circumferential strain curves were generated with a custom feature-tracking algorithm for 12 LV and 12 RV segments in each of 4-7 short-axis slices encompassing the ventricles. Temporal offsets (TOs, in ms) of the strain curves relative to a patient-specific reference curve were calculated. The intra-ventricular dyssynchrony index (DI) for each ventricle was computed as the standard deviation of the TOs. The inter-ventricular DI was calculated as the difference in median RV and median LV TOs. Compared with controls, patients had a greater LV DI (21 ± 8 vs. 11 ± 5 ms, P < 0.001) and RV DI (60 ± 19 vs. 47 ± 17 ms, P = 0.02). RV contraction was globally delayed in patients, resulting in a greater inter-ventricular DI with the RV contracting 45 ± 25 ms later than the LV vs. 12 ± 29 ms earlier in controls (P < 0.001). Inter-test reproducibility was moderate with all coefficients of variation ≤22%. Both LV and RV DIs were correlated with measures of LV, but not RV, function.
  
  
  CONCLUSIONS
  Patients with rTOF have intra- and inter-ventricular dyssynchrony, which can be quantified from standard cine CMR. This new approach can potentially help determine the contribution of dyssynchrony to ventricular dysfunction in future studies.
authors.affiliation: Departments of Pediatrics, Physiology, Biomedical Engineering and Medicine, University of Kentucky, UK Chandler Hospital, 741 S Limestone, BBSRB B353, Lexington, KY 40536, USA.
authors.forename: Linyuan
authors.initials: L
authors.lastname: Jing
authors.affiliation: Departments of Pediatrics, Physiology, Biomedical Engineering and Medicine, University of Kentucky, UK Chandler Hospital, 741 S Limestone, BBSRB B353, Lexington, KY 40536, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Haggerty
authors.affiliation: Departments of Pediatrics, Physiology, Biomedical Engineering and Medicine, University of Kentucky, UK Chandler Hospital, 741 S Limestone, BBSRB B353, Lexington, KY 40536, USA.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Suever
authors.affiliation: Departments of Pediatrics, Physiology, Biomedical Engineering and Medicine, University of Kentucky, UK Chandler Hospital, 741 S Limestone, BBSRB B353, Lexington, KY 40536, USA.
authors.forename: Sudad
authors.initials: S
authors.lastname: Alhadad
authors.affiliation: Department of Cardiology, Boston Children's Hospital, Boston, MA, USA Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
authors.forename: Ashwin
authors.initials: A
authors.lastname: Prakash
authors.affiliation: Department of Cardiology, Boston Children's Hospital, Boston, MA, USA Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Cecchin
authors.affiliation: Scientific Imaging and Visualization LLC, Atlanta, GA, USA.
authors.forename: Oskar
authors.initials: O
authors.lastname: Skrinjar
authors.affiliation: Department of Cardiology, Boston Children's Hospital, Boston, MA, USA Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
authors.forename: Tal
authors.initials: T
authors.lastname: Geva
authors.affiliation: Department of Cardiology, Boston Children's Hospital, Boston, MA, USA Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Powell
authors.affiliation: Departments of Pediatrics, Physiology, Biomedical Engineering and Medicine, University of Kentucky, UK Chandler Hospital, 741 S Limestone, BBSRB B353, Lexington, KY 40536, USA bkf@gatech.edu b.f@uky.edu.
authors.forename: Brandon K
authors.initials: BK
authors.lastname: Fornwalt
mesh_terms: D000328:Adult; D000465:Algorithms; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology*; D002037:Bundle-Branch Block / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D016022:Case-Control Studies; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013771:Tetralogy of Fallot / Q000150:complications / Q000503:physiopathology* / Q000601:surgery
keywords: Cardiac magnetic resonance; Dyssynchrony; Magnetic resonance imaging; Tetralogy of Fallot