title: A visual approach for the accurate determination of echocardiographic left ventricular ejection fraction by medical students.
abstract: BACKGROUND
  Previously published reports show that there is significant intraobserver, interobserver, and interinstitutional variability in the determination of left ventricular (LV) ejection fraction (EF) by echocardiography. With the increased deployment of echocardiography (eg, handheld devices), there exists a need for developing a simple, intuitive approach for evaluating LVEF that allows a wider range of physicians to accurately and rapidly determine LVEF.
  
  
  OBJECTIVE
  We sought to create a system for assessing LVEF that relies on recognition and matching of patterns, rather than on mathematic calculations and geometric assumptions.
  
  
  METHODS
  A library of videoclips of cardiac function was compiled from 54 patients who spanned the spectrum of LVEF. LVEFs were calculated for these patients using standard echocardiographic methods, with further validation of a subsample using cardiac magnetic resonance imaging measurement of LVEF. The library of images was used to create a software tool for assessing LVEF on the basis of a "template-matching" approach. The software tool was then tested on medical students (N=13) to determine whether it enabled relatively untrained individuals to make accurate LVEF estimates.
  
  
  RESULTS
  Using a template-matching approach for interpretation of echocardiograms, medical students were able to accurately estimate LVEF after only a limited introduction to echocardiography. Their LVEF estimates showed good correlation and agreement with gold standard (r = 0.88, standard square of the estimate = 6.0, limits of agreement = +12.0%, -15.6%).
  
  
  CONCLUSIONS
  A new visual approach for assessing cardiac function using template matching can accurately estimate LVEF. With minimal training, medical students can make LVEF estimates that correlate well with gold standard. The application of this new approach includes allowing for the interpretation of LVEF from echocardiograms to be performed by a broader spectrum of physicians.
authors.affiliation: School of Medicine, Stanford, California, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Hope
authors.forename: Erasmo
authors.initials: E
authors.lastname: de la Pena
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Yang
authors.forename: David H
authors.initials: DH
authors.lastname: Liang
authors.forename: Michael V
authors.initials: MV
authors.lastname: McConnell
authors.forename: David N
authors.initials: DN
authors.lastname: Rosenthal
mesh_terms: D000328:Adult; D000368:Aged; D002140:California; D009202:Cardiomyopathies / Q000175:diagnosis / Q000503:physiopathology; D015331:Cohort Studies; D004452:Echocardiography / Q000592:standards; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000592:standards; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D013223:Statistics as Topic; D013318:Stroke Volume / Q000502:physiology*; D013337:Students, Medical; D016277:Ventricular Function, Left / Q000502:physiology