Biventricular pacing in heart failure: back to basics in the pathophysiology of left bundle branch block to reduce the number of nonresponders
Section snippets
Pathophysiologic factors in patients who are nonresponders
Several factors could be responsible for this relatively high prevalence of patients with an unchanged or worsened condition. One reason could be the lack of simultaneous activation of each wall of the left ventricle together with its own specular segment (intraventricular dyssynchrony). Such unfavorable mechanical activation of the left ventricle may persist after biventricular pacing, notwithstanding the simultaneous activation of left and right ventricles (interventricular
Imaging and diagnostic testing to evaluate nonresponder patients
In such a clinical condition, the accuracy of M-mode echocardiography in detecting the most delayed wall could be reduced by the lack of a substantial gradient between the left ventricular walls because of the uniformity in the activation delay throughout the entire left ventricular mass. For this reason, we have proposed tissue Doppler imaging as a more accurate technique than the traditional M-mode or 2-dimensional echocardiography in determining the optimum pacing site before the
Conclusions
In conclusion, we believe the following: (1) Although there is compelling evidence that biventricular pacing may be beneficial in nonpharmacologic treatment of advanced heart failure, patients with LBBB may have several differences in electromechanical activation patterns, and thus an individual assessment, as well as a pathophysiologic characterization of the LBBB type, should be undertaken before any decision about the pacing is made. (2) In theory, the site of the left ventricular delay
Acknowledgements
The authors thank Mary Monique Rendall, BA, for reviewing the manuscript, and Rossano Salidu for reviewing the iconography.
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