title: Radial and longitudinal strain and strain rate assessed by speckle-tracking echocardiography in dogs with myxomatous mitral valve disease.
abstract: BACKGROUND
  Assessment of left ventricular (LV) function using conventional echocardiographic methods is difficult in mitral regurgitation (MR) owing to altered hemodynamic loading conditions. Newer methods such as speckle-tracking echocardiography (STE) provide assessment of LV strain (St) and strain rates (SR).
  
  
  OBJECTIVE
  Global St and SR are 1) decreased in dogs with clinical signs of congestive heart failure (CHF) due to myxomatous mitral valve disease (MMVD) compared with clinically healthy dogs, and are 2) associated with conventional echocardiographic indices of MMVD severity.
  
  
  METHODS
  The study subjects were 93 privately owned dogs with different MMVD severities.
  
  
  METHODS
  Prospectively recruited dogs were grouped according to MMVD severity based on echocardiographic evaluation of MR and presence of clinical signs. Global radial and longitudinal St, SR, and indices of LV dyssynchrony were assessed.
  
  
  RESULTS
  On group-wise comparisons, dogs with CHF had increased global longitudinal St, global longitudinal and radial SR in systole (SRs), and early diastole (SRe) compared with dogs with no or minimal MR (all P < .04). On multiple regression analyses, these global STE variables increased with degree of MR, but associations with left atrial-to-aortic root ratio (LA/Ao) were best described by second-order polynomial equations. Thus, curvilinear relationships were found for LA/Ao and longitudinal St, SRs, and SRe (all P < .002) and radial St and SRe (all P < .001).
  
  
  CONCLUSIONS
  Assessed by STE, LV function appeared to be augmented in moderate-to-severe disease. However, at CHF stages with greatly enlarged atria, a decrease to levels comparable to dogs with no or minimal MR was observed.
authors.affiliation: Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark. nez@life.ku.dk
authors.forename: N E
authors.initials: NE
authors.lastname: Zois
authors.forename: A
authors.initials: A
authors.lastname: Tidholm
authors.forename: K M
authors.initials: KM
authors.lastname: Nägga
authors.forename: S G
authors.initials: SG
authors.lastname: Moesgaard
authors.forename: C E
authors.initials: CE
authors.lastname: Rasmussen
authors.forename: T
authors.initials: T
authors.lastname: Falk
authors.forename: J
authors.initials: J
authors.lastname: Häggström
authors.forename: H D
authors.initials: HD
authors.lastname: Pedersen
authors.forename: B
authors.initials: B
authors.lastname: Åblad
authors.forename: H Y
authors.initials: HY
authors.lastname: Nilsen
authors.forename: L H
authors.initials: LH
authors.lastname: Olsen
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis / Q000473:pathology*; D004285:Dogs; D004452:Echocardiography / Q000379:methods / Q000662:veterinary*; D008945:Mitral Valve Prolapse / Q000473:pathology / Q000662:veterinary*; D015588:Observer Variation; D015203:Reproducibility of Results; D018487:Ventricular Dysfunction, Left / Q000473:pathology / Q000662:veterinary