September 30, 2002Open Access
Ver artículo completoSystolic Improvement and Mechanical Resynchronization Does Not Require Electrical Synchrony in the Dilated Failing Heart With Left Bundle-Branch Block
PICO estructurado
Does left ventricular or biventricular pacing improve mechanical synchrony and function without requiring electrical synchrony in dogs with LBBB-failing hearts?
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Población
Dogs with left bundle-branch block (LBBB)-failing hearts
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Intervención
Left ventricular (LV) and Biventricular (BiV) pacing
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Comparador
Right atrial pacing-LBBB
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Resultado
Chamber hemodynamics (dP/dt(max) and aortic pulse pressure), mechanical resynchronization, and electrical dispersion measured by epicardial mapping, tagged MRI, and hemodynamicssurrogate
In a canine model of LBBB heart failure, mechanical coordination rather than electrical synchrony was found to be the primary driver of systolic improvement during LV or BiV pacing.
Resumen
BACKGROUND: Biventricular (BiV) and left ventricular (LV) pacing similarly augment systolic function in left bundle-branch block (LBBB)-failing hearts despite different electrical activation. We tested whether electrical synchrony is required to achieve mechanical synchronization and functional benefit from pacing. METHODS AND RESULTS: Epicardial mapping, tagged MRI, and hemodynamics were obtained in dogs with LBBB-failing hearts during right atrial, LV, and BiV stimulation. BiV and LV both significantly improved chamber hemodynamics (eg, 25% increase in dP/dt(max) and aortic pulse pressure) compared with atrial pacing-LBBB, and this improvement correlated with mechanical resynchronization. Electrical dispersion, however, decreased 13% with BiV but increased 23% with LV pacing (P<0.01). CONCLUSION: Improved mechanical synchrony and function do not require electrical synchrony. Mechanical coordination plays the dominant role in global systolic improvement with either pacing approach.