title: Quantitation of basal dyssynchrony and acute resynchronization from left or biventricular pacing by novel echo-contrast variability imaging.
abstract: OBJECTIVE
  This study sought to test a novel echocardiographic method based on contrast variability imaging (CVI), to quantify cardiac dyssynchrony and magnitude of resynchronization achieved by left ventricular (LV) and biventricular (BiV) pacing therapy.
  
  
  BACKGROUND
  Left ventricular or BiV pacing is a promising new therapy for patients with heart failure and intraventricular conduction delay. However, precise quantitation of the extent of resynchronization achieved remains scant.
  
  
  METHODS
  Ten patients treated with BiV or LV pacing therapy were studied. Echo-contrast was infused slowly, and gated images were acquired before and during contrast appearance. The temporally normalized variance derived from 30 to 50 sequential beats was determined at each pixel to yield the CVI image-displaying improved wall delineation. Systolic regional fractional area of radial sectors was calculated with active and temporarily suspended (AAI) pacing. All analyses were performed blinded to both patient and treatment.
  
  
  RESULTS
  Pacing increased septal inward motion from -20.4 +/- 9.6% to -30.5 +/- 14.0%, whereas lateral wall motion occurred earlier with no net magnitude change. Both spatial and temporal dyssynchrony in the LV declined nearly 40% with LV or BiV pacing (p < or = 0.001), and this correlated with increasing ejection fraction (31% to 39%; p < 0.02; p < 0.004 for correlation with dyssynchrony).
  
  
  CONCLUSIONS
  The new imaging and regional dyssynchrony analysis methods provide quantitative assessment of resynchronization analogous to that previously obtained only by tagged magnetic resonance imaging. This could provide a useful noninvasive method for both identifying candidates and following long-term therapy.
authors.affiliation: Division of Cardiology, Department of Medicine, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors.forename: Miho
authors.initials: M
authors.lastname: Kawaguchi
authors.forename: Taizo
authors.initials: T
authors.lastname: Murabayashi
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Fetics
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Nelson
authors.forename: Hisanori
authors.initials: H
authors.lastname: Samejima
authors.forename: Erez
authors.initials: E
authors.lastname: Nevo
authors.forename: David A
authors.initials: DA
authors.lastname: Kass
mesh_terms: D002304:Cardiac Pacing, Artificial; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging*; D015150:Echocardiography, Doppler / Q000379:methods*; D015637:Gated Blood-Pool Imaging / Q000379:methods*; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008875:Middle Aged