Session S24.3

Analysis of Body Surface Potential Maps in Cardiac Resynchronization Therapy

MS Guillem*, R Brugada, B Thibault, AM Climent, J Millet

Universitat Politècnica de València
Valencia, Spain

Cardiac resynchronization therapy (CRT) aims at improving systolic function in patients with heart failure. Improvement in systolic function is based on a recovery of synchrony in the contraction of both ventricles by biventricular pacing, specially when the intraventricular delay is optimized for each patient. We investigated the use of body surface potential mapping (BSPM) in the understanding of the activation sequence in the myocardium during biventricular (BiV) pacing that can benefit the individual optimization of the programmed intraventricular delay.
We acquired BSPM recordings in 29 patients with an implanted BiV device during normal sinus rhythm, right ventricular (RV) pacing, left ventricular (LV) pacing and BiV pacing, 9 of them with varying intraventricular delays. We compared potential maps during BiV pacing to those during RV pacing and LV pacing by a 2-D correlation. Mean correlation indexes during the QRS complex were computed for comparing BiV and RV pacing maps and BiV and LV pacing maps. Dissimilarity index was defined as the absolute difference between mean correlation indexes for RV pacing and LV pacing. BiV pacing maps were classified into three groups according to their computed mean correlations and dissimilarity indexes: RBiV (high correlation with RV pacing maps and high dissimilarity index), LBiV (high correlation with LV pacing maps and high dissimilarity index) or IBiV (otherwise).
BiV surface potential maps of 3 patients (10%) were classified into RBiV group, 8 patients (28%) were into LBiV group and the remaining 18 patients (62%) were classified into IBiV group. Even when BiV stimulation presented a similar activation pattern than a single lead activation pattern, QRS width was reduced by using a second lead in most of these patients. Stimulation with a second lead may not be changing the global activation pattern but making it faster. Another observation that arises from this study is the similarity of BiV map patterns to RV or LV map patterns when the interventricular delay is 60 ms or more. Stimulation of the second ventricle 60 ms or later than the first stimulated ventricle makes the second stimulation have no effect on the activation pattern.
Study of body surface maps during biventricular activation may help in the understanding of the activation patterns in the myocardium, allowing the discrimination of BiV patterns to those of RV or LV activations. Further study of these body surface maps may help in the optimization in the programming mode of BiV devices individualized for each patient.

(Abstract Control Number: 77)