title: Timely Pulmonary Valve Replacement May Allow Preservation of Left Ventricular Circumferential Strain in Patients with Tetralogy of Fallot.
abstract: BACKGROUND
  Patients with Tetralogy of Fallot (TOF) and pulmonary insufficiency and a dilated right ventricle (RV) may suffer from a reduction in left ventricular (LV) performance. It is not clear whether timely pulmonary valve replacement (PVR) preserves LV mechanics.
  
  
  METHODS
  Ten TOF patients who underwent PVR were identified from hospital records, and pre- and postoperative cardiac magnetic resonance images were post-processed with a semi-automatic tissue tracking software. LV circumferential strain, time to peak strain, and torsion were compared before and after PVR. A control group of 10 age-matched normal volunteers was assessed as a comparison.
  
  
  RESULTS
  LV circumferential strain did not change before vs. after PVR (basal -18.3 ± 3.7 vs. -20.5 ± 3%,p= 0.082; mid-ventricular -18.4 ± 3.6 vs. -19.1 ± 2%,p= 0.571; apical -22.7 ± 5.2 vs. -22.1 ± 4%;p= 0.703). There was also no difference seen between the baseline strain and normal controls (control basal -18.2 ± 3.3%,p= 0.937; mid -18 ± 3.2%,p= 0.798; apex -24.1 ± 5%,p= 0.552). LV torsion remained unchanged from baseline to post PVR [systolic 2.75 (1.23-9.51) °/cm vs. 2.3 ± 1.2°/cm,p= 0.285; maximum 5.5 ± 3.5°/cm vs. 2.34 (1.37-8.07) °/cm,p= 0.083]. There was no difference in time to measured peak LV circumferential strain before vs. after PVR (basal 0.44 ± 0.1 vs. 0.43 ± 0.05,p= 0.912; mid-ventricular 0.42 ± 0.08 vs. 0.38 ± 0.06,p= 0.186; apical 0.40 ± 0.08 vs. 0.40 ± 0.06,p= 0.995). At the same time, pulmonary regurgitation and RV end-diastolic and end-systolic volume indices decreased and LV end-diastolic volume increased after PVR. RV and LV ejection fractions remained constant.
  
  
  CONCLUSIONS
  PVR allows for favorable remodeling of both ventricular volumes for TOF patients with significant pulmonary regurgitation. In this cohort, LV myocardial functional parameters such as circumferential strain, time to peak strain, and LV torsion were normal at baseline and remain unchanged after PVR.
authors.affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA; Pediatric Heart Center, University Children's Hospital Zurich, Zurich, Switzerland.
authors.forename: Barbara E U
authors.initials: BE
authors.lastname: Burkhardt
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London , London , UK.
authors.forename: Marí Nieves
authors.initials: MN
authors.lastname: Velasco Forte
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London , London , UK.
authors.forename: Saravanan
authors.initials: S
authors.lastname: Durairaj
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London , London , UK.
authors.forename: Isma
authors.initials: I
authors.lastname: Rafiq
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London , London , UK.
authors.forename: Israel
authors.initials: I
authors.lastname: Valverde
authors.affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center , Dallas, TX , USA.
authors.forename: Animesh
authors.initials: A
authors.lastname: Tandon
authors.affiliation: Division of Imaging Sciences and Biomedical Engineering, King's College London , London , UK.
authors.forename: John
authors.initials: J
authors.lastname: Simpson
authors.affiliation: Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, USA; Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK.
authors.forename: Tarique
authors.initials: T
authors.lastname: Hussain
keywords: Tetralogy of Fallot; congenital heart defects; left ventricle; magnetic resonance; myocardial function; pulmonary valve replacement; strain; tissue tracking