Abstract 2515: Endocardial Left Ventricular Pacing Improves Cardiac Resynchronization Therapy In Canine Lbbb Hearts
Introduction: Cardiac resynchronization therapy (CRT) by biventricular (BiV) or left ventricular (LV) pacing is usually achieved using epicardial (EPI) LV pacing. Physiological activation starts from the LV endocardium (ENDO), but LV ENDO pacing is avoided due to inherent risks. Technical improvements, like novel leadless pacing may make ENDO pacing feasible.
Hypothesis: LV ENDO pacing provides more synchronous activation and better pump function during CRT than LV EPI pacing.
Methods: In 6 anesthetized dogs left bundle branch block (LBBB) was induced by radio-frequency ablation. Pacing leads were positioned in the right atrium (RA), right ventricle (RV) and at 8 paired (EPI and ENDO) LV sites. LV pressure and LVdP/dtmax were measured as well as synchrony of electrical activation of the LV using ~100 electrodes positioned on the epicardium and endocardium of RV and LV. For each LV site measurements were performed during BiV pacing and during LV pacing over a range of AV-delays.
Results: During BiV pacing the % reduction in LV asynchrony and % increase in LVdP/dtmax were ~2x higher during ENDO than during EPI pacing (figure⇓). During LV pacing the range of AV-delays with a >10% change in LV asynchrony (79 ± 31 vs. 32 ± 24 ms, p < 0.05) and LVdP/dtmax (92 ± 29 vs. 63 ± 39 ms) was significantly longer for ENDO than for EPI pacing. A > 10% increase in LVdP/dtmax was found more frequently during ENDO (96 ± 6%) than during EPI pacing (64 ± 8%, p < 0.05).
Conclusions: In this acute model of LBBB, the electrical and hemodynamic benefits of CRT are considerably larger during LV ENDO than during conventional LV EPI stimulation and these benefits are less dependent on timing and site of LV stimulation.