title: Velocity vector imaging fails to quantify regional myocardial dysfunction in a mouse model of isoprenaline-induced cardiotoxicity.
abstract: BACKGROUND
  Regional myocardial deformation patterns are important in a variety of cardiac diseases, including stress-induced cardiomyopathy. Velocity-vector-based imaging is a speckle-tracking echocardiography (STE)-based algorithm that has been shown to allow in-depth cardiac phenotyping in humans. Regional posterior wall myocardial dysfunction occurs during severe isoprenaline stress in mice. We have previously shown that regional posterior wall end-systolic transmural strain decreases after severe isoprenaline toxicity in mice. We hypothesize that STE can detect and further quantify these perturbations.
  
  
  RESULTS
  Twenty-three mice underwent echocardiographic examination using the VEVO2100 system. Regional transmural radial strain and strain rate were calculated in both parasternal short-axis and parasternal long-axis cine loops using the VisualSonics VEVO 2100 velocity vector imaging (VVI) STE algorithm. Eight C57BL/6 mice underwent baseline echocardiographic examination using the VisualSonics VEVO 770 system, which can acquire >1,000 frames/s cine loops. In a parasternal short-axis cine loop, the heart was divided into six segments, and regional fractional wall thickening (FWT) was assessed manually. The same protocols were also performed 90 minutes post 400 mg/kg intraperitoneally isoprenaline. Regional myocardial FWT is uniform at baseline but increases significantly in anterolateral segments, whereas it decreases significantly in posterior segments (P < 0.05). A similar pattern is seen using the VVI algorithm although the variance is larger, and differences are smaller and fail to reach significance.
  
  
  CONCLUSIONS
  VVI is less sensitive in detecting regional perturbations in myocardial function than manual tracing, possibly due to the low frame rate in the cine loops used.
authors.affiliation: Wallenberg Laboratory, Department of Molecular and Clinical Medicine/C, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden Division of Cardiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Margareta Scharin
authors.initials: MS
authors.lastname: Täng
authors.forename: Bjorn
authors.initials: B
authors.lastname: Redfors
authors.forename: Yangzhen
authors.initials: Y
authors.lastname: Shao
authors.forename: Elmir
authors.initials: E
authors.lastname: Omerovic
mesh_terms: D000465:Algorithms; D000818:Animals; D004195:Disease Models, Animal; D004452:Echocardiography / Q000379:methods*; D054459:Elasticity Imaging Techniques / Q000379:methods*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007545:Isoproterenol; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000139:chemically induced* / Q000000981:diagnostic imaging*
chemical_list: D007545:Isoproterenol