Published Online
on August 10, 2009

A more recent version of this article appeared on October 1, 2009

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Original Article

LV Endocardial Pacing Improves Resynchronization Therapy in Canine LBBB Hearts

Caroline van Deursen¹; Irene E. van Geldorp¹; Leonard M. Rademakers¹; Arne van Hunnik¹; Marion Kuiper¹; Catherine Klersy²; Angelo Auricchio³ and Frits W. Prinzen^1,4

¹ Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands;
² IRCCS Fondazione Policlinico San Matteo, Pavia, Italy;
³ Fondazione Cardiocentro Ticino, Lugano, Switzerland

^* Corresponding author; email: frits.prinzen{at}fys.unimaas.nl

Background—To investigate the benefits of the more physiological activation achieved by left ventricular (LV) endocardial pacing (ENDO) as compared to conventional epicardial (EPI) LV pacing in Cardiac resynchronization therapy (CRT).

Methods and Results—In 8 anesthetized dogs with experimental left bundle branch block pacing leads were positioned in right atrium, right ventricle and at 8 paired (EPI and ENDO) LV sites. Systolic LV pump function was assessed as LVdP/dtmax and stroke work and diastolic function as LVdP/dtmin. Electrical activation and dispersion of repolarization were determined from 122 epicardial and endocardial electrodes and from analysis of the surface ECG. Overall, ENDO-biventricular (BiV) pacing more than doubled the degree of electrical resynchronization and increased the benefit on LVdP/dtmax and stroke work by 90% and 50%, respectively, as compared to EPI-BiV pacing. During single site LV pacing the range of AV intervals with a >10% increase in LV resynchronization (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. EPI-BiV, but not ENDO-BiV, pacing created a significant (40±21 ms) transmural dispersion of repolarization.

Conclusions—Data from this acute animal study indicates that the use of an endocardial LV pacing electrode may increase efficacy of CRT as compared to conventional epicardial CRT.

Key Words: bundle-branch block • electrophysiology • hemodynamics • pacing