Background: Research is needed to explore the relative benefits of alternative electrode placements in biventricular and left ventricular pacing for heart failure with left bundle branch block (LBBB). Methods: A fast computational model of the left ventricle, running on an ordinary laptop computer, was created to simulate the spread of electrical activation over the myocardial surface, together with the resulting electrocardiogram, segmental wall motion, stroke volume, and ejection fraction in the presence of varying degrees of mitral regurgitation. Arbitrary zones of scar and blocked electrical conduction could be modeled. Results: Simulations showed there are both sweet spots and poor spots for left ventricular electrode placement, sometimes separated by only a few centimeters. In heart failure with LBBB pacing at poor spots can produce little benefit or even reduced pumping effectiveness. Pacing at sweet spots can produce up to 35% improvement in ejection fraction. Relatively larger benefit occurs in dilated hearts, in keeping with the greater disparity between early and late activated muscle. Sweet spots are typically located on the basal to mid-level, inferolateral wall. Poor spots are located on or near the interventricular septum. Anteroapical scar with conduction block causes little shift in locations for optimal pacing. Hearts with increased passive ventricular compliance and absence of pre-ejection mitral regurgitation exhibit greater therapeutic gain. The durations and wave shapes of QRS complexes in the electrocardiogram can help predict optimum electrode placement in real time. Conclusions: Differences between poor responders and hyper-responders to cardiac resynchronization therapy can be understood in terms of basic anatomy, physiology, and pathophysiology. Computational modeling suggests general strategies for optimal electrode placement. In a given patient heart size, regional pathology, and regional dynamics allow individual pre-treatment planning to target optimal electrode placement.
bundle-branch block, heart failure, mapping, mitral regurgitation
Date of this Version
Babbs, Charles F., "Optimizing Electrode Placement for Hemodynamic Benefit in Cardiac Resynchronization Therapy" (2012). Weldon School of Biomedical Engineering Faculty Publications. Paper 57.