title: Longitudinal strain impairment as a marker of the progression of heart failure with preserved ejection fraction in a rat model.
abstract: BACKGROUND
  Recent advances in very high frame rate use of ultrasonography have enabled the application of two-dimensional speckle-tracking echocardiography (STE) to small animal cardiac functional assessments. In this study, two-dimensional STE was applied to a rat model of hypertensive heart failure with preserved ejection fraction to clarify consequences of left ventricular (LV) wall deformation in the progression of heart failure with preserved ejection fraction.
  
  
  METHODS
  STE was performed every 2 weeks in Dahl salt-sensitive rats fed a 0.3% (control group) or 8% (hypertension [HT] group) sodium chloride diet from 6 to 14 weeks of age. Longitudinal, radial, and circumferential global strain and strain rate were measured, and the time courses of these parameters were observed.
  
  
  RESULTS
  Deterioration of longitudinal strain occurred in the early phase of the progression of LV hypertrophy and continued to worsen until congestive heart failure developed (longitudinal strain in the HT group: 25 ± 3% at 10 weeks, 21 ± 4% at 12 weeks, and 18 ± 2% at 14 weeks; longitudinal strain in controls was preserved during the experimental period). At 12 weeks, radial strain (HT group, 35 ± 7%; controls, 41 ± 10%) had deteriorated at the late stage of manifest diastolic dysfunction. Throughout the experiments, circumferential strain was preserved (HT group, 35 ± 6%; control group, 35 ± 5%), and no significant increase in short-axis function was observed.
  
  
  CONCLUSIONS
  STE is applicable to the small animal heart and detected LV wall long-axis dysfunction preceding short-axis dysfunction or overt congestive heart failure in the progression of hypertensive LV hypertrophy in a rat model.
authors.affiliation: Department of Medical Sciences, University of Tsukuba, Tsukuba, Japan.
authors.forename: Rumi
authors.initials: R
authors.lastname: Koshizuka
authors.forename: Tomoko
authors.initials: T
authors.lastname: Ishizu
authors.forename: Yuri
authors.initials: Y
authors.lastname: Kameda
authors.forename: Ryo
authors.initials: R
authors.lastname: Kawamura
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Seo
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Aonuma
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D018450:Disease Progression; D004452:Echocardiography / Q000379:methods*; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D051381:Rats; D020303:Rats, Inbred Dahl; D015203:Reproducibility of Results; D013318:Stroke Volume