1. Understanding the cardiac substrate and the underlying physiology: Implications for individualized treatment algorithm 
John Gorcsan, MD, Frits W. Prinzen, PhD 
Heart Rhythm 
Volume 9, Issue 8, Pages S18-S26 (August 2012)
DOI: /j.hrthm
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2. Figure 1
Reconstruction of electrical activation in the ventricles based on contact mapping at the epicardium and noncontact mapping of the left ventricular (LV) endocardium of a canine heart before and during left bundle branch block (LBBB), the latter before and during biventricular pacing. During LBBB, activation initiates in the right ventricular (RV) wall and slowly progresses through the septal wall and along the LV apex toward the LV basal lateral wall. In this example of biventricular pacing, the pacing electrodes were positioned in the RV apex and at the epicardium of the mid-lateral wall.
Heart Rhythm 2012 9, S18-S26DOI: ( /j.hrthm )
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3. Figure 2
Diminished left ventricular dyssynchrony and impact of resynchronization in failing hearts with right vs left bundle branch block.
(Reproduced with permission from Byrne MJ, Helm RH, Daya S, et al. Diminished left ventricular dyssynchrony and impact of resynchronization in failing hearts with right versus left bundle branch block. J Am Coll Cardiol 2007;50:1484– )
Heart Rhythm 2012 9, S18-S26DOI: ( /j.hrthm )
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4. Figure 3
Scatterplot showing (A) the distribution of the standard deviation of the time to peak myocardial sustained systolic velocity (TS-SD) and (B) early diastolic velocity (TE-SD) of all 12 left ventricular segments in normal controls, in patients with heart failure and narrow QRS complexes, and in patients with heart failure and wide QRS complexes. *P <.001 vs controls; †P = .009 vs normal QRS group; ‡P = .002 vs normal QRS group.
(Reproduced with permission from Yu C-M, Lin H, Zhang Q, Sanderson JE. High prevalence of left ventricular systolic and diastolic asynchrony in patients with congestive heart failure and normal QRS duration. Heart 2003;89:54–60.43)
Heart Rhythm 2012 9, S18-S26DOI: ( /j.hrthm )
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5. Figure 4
Reverse remodeling response to resynchronization therapy. Bar graphs of mean end-systolic volume values before and 8 ± 5 months after cardiac resynchronization therapy (CRT) in patients with borderline QRS duration with and without significant radial dyssynchrony.
(Reproduced with permission from Oyenuga O, Hara H, Tanaka H, et al. Usefulness of echocardiographic dyssynchrony in patients with borderline QRS duration to assist with selection for cardiac resynchronization therapy. JACC Cardiol Imaging 2010;3:132–140.49)
Heart Rhythm 2012 9, S18-S26DOI: ( /j.hrthm )
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6. Figure 5
Algorithm to help determine whether a patient has a high or low likelihood of response to cardiac resynchronization therapy (CRT), integrating information on how various factors for prediction of response to CRT may improve response rates. Important issues are left ventricular (LV) dyssynchrony, left bundle branch block (LBBB) morphology in the QRS complex of the ECG, scar tissue in the region where the LV pacing lead is positioned, total extent of scar in the LV, and whether the LV lead is positioned in the site of latest mechanical activation. Note that absence of positive predictors of CRT response and presence of negative predictors may lead to adverse effect of CRT, as has been shown for an LV lead positioned in the scar and CRT in patients with intraventricular conduction delay (IVCD). HF = heart failure.
Heart Rhythm 2012 9, S18-S26DOI: ( /j.hrthm )
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