Left ventricular endocardial pacing improves resynchronization therapy in canine left bundle-branch hearts.
BACKGROUND
We investigated the benefits of the more physiological activation achieved by left ventricular (LV) endocardial pacing (ENDO) as compared with conventional epicardial (EPI) LV pacing in cardiac resynchronization therapy.


RESULTS
In 8 anesthetized dogs with experimental left bundle-branch block, pacing leads were positioned in the 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 with EPI-BiV pacing. During single-site LV pacing, the range of AV intervals with a >10% increase in LV resynchronization (79+/-31 versus 32+/-24 ms, P<0.05) and LVdP/dtmax (92+/-29 versus 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 indicate that the use of an endocardial LV pacing electrode may increase the efficacy of resynchronization therapy as compared with conventional epicardial resynchronization therapy.
Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht, 6200 MD Maastricht, The Netherlands.
Caroline
C
van Deursen
Irene E
IE
van Geldorp
Leonard M
LM
Rademakers
Arne
A
van Hunnik
Marion
M
Kuiper
Catherine
C
Klersy
Angelo
A
Auricchio
Frits W
FW
Prinzen
D000818:Animals; D002037:Bundle-Branch Block / Q000503:physiopathology* / Q000628:therapy*; D006328:Cardiac Catheterization; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004285:Dogs; D004562:Electrocardiography; D006439:Hemodynamics / Q000502:physiology; D023421:Models, Animal; D008955:Models, Cardiovascular; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology* / Q000628:therapy*