Electromechanical model of cardiac resynchronization in the dilated failing heart with left bundle branch block.

Experimental studies have shown that biventricular pacing can improve systolic function in the failing heart with bundle branch block. The goal of this study was to develop and validate a three-dimensional computational model of the dilated failing heart with left bundle branch block to investigate how biventricular pacing can improve systolic mechanical performance and synchrony. In an anatomically detailed model of canine ventricular geometry, fiber architecture and Purkinje fiber network structure, a monodomain solution for anisotropic impulse conduction gave rise to electrical activation sequences that were consistent with experimentally observed patterns. Coupling this with regional myocardial mechanics computed for left branch bundle block and biventricular pacing showed good agreement with published regional fiber strains measured in dogs by using magnetic resonance imaging tagging. Biventricular pacing improved mechanical synchrony and systolic function in the computational model. The model may be a useful tool for investigating the pacing conditions required to achieve optimal mechanical improvement in the failing heart, especially because electrical synchrony does not correlate directly with mechanical synchrony and performance.