Bordacher, Pierre, Grenz, Nathan, Jais, Pierre, Ritter, Philippe, Leclercq, Christophe, Morgan, John M., Gras, Daniel and Yang, Ping
Left ventricular endocardial or triventricular pacing to optimize cardiac resynchronization therapy in a chronic canine model of ischemic heart
American Journal of Physiology: Heart and Circulatory Physiology (doi:10.1152/ajpheart.01117.2011).
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Background: Cardiac resynchronization therapy (CRT) is a proven treatment for heart failure but approximately 30% of patients appear to not benefit from the therapy. Left ventricular (LV) endocardial (Endo) and multisite epicardial (TriV) pacing have been proposed as alternatives to traditional LV transvenous epicardial (Epi) pacing, but no study has directly compared the hemodynamic effects of these approaches.
Methods and Results: Left bundle branch block (LBBB) ablation was performed and repeated microembolizations were performed in dogs to reduce LV ejection fraction (EF) to less than 35%. LV dP/dtmax and other hemodynamic indices were measured with a conductance catheter during LV Epi, LV Endo, Biventricular (BiV) Epi, BiV Endo and TriV pacing performed at 3 AV delays. LV Endo pacing was obtained with a clinically-available pacing system. The optimal site was defined as the site that increased dP/dtmax by the largest percentage. Implantation of the Endo lead was feasible in all canines (n=8) without increased mitral regurgitation seen with transesophageal echocardiography and with full access to the different LV Endo pacing sites. BiV Endo pacing increased dP/dtmax more than BiV Epi and TriV pacing on average (p<.01) and at the optimal site (p<.01). There were no significant differences between BiV Epi and TriV pacing.
Conclusions: BiV Endo pacing was superior to BiV Epi and to TriV pacing in terms of acute hemodynamic response. Further investigation is needed to confirm the chronic benefit of this approach in humans.
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