title: Comparison of four echocardiographic methods to determine left atrial size in dogs.
abstract: OBJECTIVE
  To compare a linear and three volume-based two-dimensional echocardiographic methods for measuring LA size: left atrium to aorta ratio (LA/Ao ratio), biplane area-length, biplane modified Simpson and monoplane area-length.
  
  
  METHODS
  One hundred seventy-six client-owned dogs of different breeds, 88 healthy dogs and 88 dogs with myxomatous mitral valve disease of different disease severity.
  
  
  METHODS
  The left apical four- and two-chamber views were used to measure LA volumes. The right parasternal short-axis view at the level of the heart base was used to measure the LA/Ao ratio.
  
  
  RESULTS
  The biplane area-length method yielded 2.8% larger values than those of the biplane modified Simpson method, consistent across the full range of LA volumes. The monoplane area-length method derived on average 5.8% larger values of LA volume than the biplane area-length method. The difference between these two methods was most pronounced at larger LA volumes. The relation between the LA/Ao ratio and LA volume was curvilinear and with increasing LA size these two methods derived very dissimilar values.
  
  
  CONCLUSIONS
  All methods showed good feasibility and reproducibility, with the volume-based methods having the most favourable intra- and inter-observer variabilities. The LA/Ao ratio underestimates at higher values of LA size compared to the biplane area-length method. LA volume methods may be superior to the LA/Ao ratio in quantification of LA size. The biplane area-length method and biplane modified Simpson method can be used interchangeably. The monoplane area-length measurement may be used as a quick and reliable method for assessment of LA size in clinical practice.
authors.affiliation: Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark. Electronic address: mh@sund.ku.dk.
authors.forename: M
authors.initials: M
authors.lastname: Höllmer
authors.affiliation: Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: J L
authors.initials: JL
authors.lastname: Willesen
authors.affiliation: Department of Mathematics and Statistics, Faculty of Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Tolver
authors.affiliation: Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Koch
mesh_terms: D000818:Animals; D004285:Dogs / Q000033:anatomy & histology*; D004452:Echocardiography / Q000379:methods / Q000662:veterinary*; D006325:Heart Atria / Q000033:anatomy & histology*; D006349:Heart Valve Diseases / Q000000981:diagnostic imaging / Q000662:veterinary; D008943:Mitral Valve / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D009929:Organ Size; D015203:Reproducibility of Results
keywords: Biplane area-length method; Biplane modified Simpson method; LA volume; LA/Ao ratio; Myxomatous mitral valve disease