title: Left ventricular mechanical discoordination in nonischemic hearts: relationship with left ventricular function, geometry, and electrical dyssynchrony.
abstract: BACKGROUND
  Mechanical discoordination (MD) is known as a myocardial deformation of opposite strain during ejection, reflecting dyssynchronous electrical activation. We used speckle tracking echocardiography to examine the relationship between MD, left ventricular (LV) function and geometry, as well as electrical dyssynchrony in various nonischemic hearts.
  
  
  RESULTS
  We examined 131 subjects (left bundle branch block [LBBB] 27; dilated cardiomyopathy [DCM] without LBBB 33; LV hypertrophy 28; and normal heart 43) using circumferential strain rate analysis. Integration of positive (stretch) and negative (shortening) components during the ejection time was obtained in the mid-ventricular level for 6 myocardial segments, and MD was quantified as the stretch to shortening ratio (SSR). The SSR in the septal region (anteroseptal and septal segments) was markedly elevated in the LBBB and DCM groups compared with the other groups. With univariate analysis, SSR over the septal region was found to be correlated with QRS duration, LV end-diastolic dimension, and LV ejection fraction. Multivariate analysis revealed that QRS duration and LV ejection fraction were significant independent determinants of SSR for the septal region.
  
  
  CONCLUSIONS
  In nonischemic hearts, electrical dyssynchrony and LV dysfunction may contribute synergistically to MD in the septal region. The finding that non-LBBB DCM patients exhibited a certain amount of SSR may provide new insight into therapeutic strategies for cardiac resynchronization therapy.
authors: Department of Cardiology, Osaka Medical College, Osaka, Japan.
authors: Shinsaku
authors: S
authors: Shimamoto
authors: Takahide
authors: T
authors: Ito
authors: Shimpei
authors: S
authors: Nogi
authors: Shun
authors: S
authors: Kizawa
authors: Nobukazu
authors: N
authors: Ishizaka
mesh_terms: D000368:Aged; D002037:Bundle-Branch Block / Q000000981:diagnostic imaging / Q000503:physiopathology; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006321:Heart / Q000503:physiopathology*; D006352:Heart Ventricles / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000503:physiopathology
keywords: cardiomyopathy; myocardial function; strain rate imaging