title: Comparative value of single-beat load-independent contractility indices in dilated cardiomyopathy and mitral regurgitation.
abstract: OBJECTIVE
  We sought to compare single-beat estimates of contractility indices.
  
  
  METHODS
  Echocardiography was performed for 6 control patients, 8 patients with dilated cardiomyopathy, and 9 patients with mitral regurgitation (MR). Left ventricular volume waveform, outflow tract velocities, and mitral annulus velocities were recorded with carotid tonometry. Numeric simulations were used to generate the same data while varying contractility, compliance, and MR. Estimates of elastance (normalized systolic and bilinearly approximated), preload-recruitable stroke work, and preload-adjusted maximal power were calculated.
  
  
  RESULTS
  Normalized systolic and bilinearly approximated elastance were decreased in patients with dilated cardiomyopathy (P <.005 for both) and MR (P =.0002 and.02, respectively). Preload-recruitable stroke work and preload-adjusted maximal power were decreased in patients with dilated cardiomyopathy only (P <.005 for both). Simulations confirmed that these differences are a result of dissimilar behavior of estimates if MR or compliance change.
  
  
  CONCLUSIONS
  Single-beat indices are decreased in dilated cardiomyopathy, but in MR show dissimilar behavior.
authors.affiliation: Cardiovascular Imaging Center, The Cleveland Clinic Foundation, Ohio 44195, USA.
authors.forename: Zoran B
authors.initials: ZB
authors.lastname: Popović
authors.forename: Milan
authors.initials: M
authors.lastname: Vuković
authors.forename: Neil
authors.initials: N
authors.lastname: Greenberg
authors.forename: Alja
authors.initials: A
authors.lastname: Vlahović
authors.forename: Aleksandar N
authors.initials: AN
authors.lastname: Nesković
authors.forename: James D
authors.initials: JD
authors.lastname: Thomas
mesh_terms: D000328:Adult; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging*; D016022:Case-Control Studies; D004452:Echocardiography; D015150:Echocardiography, Doppler; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging*; D009200:Myocardial Contraction; D013318:Stroke Volume / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology