BODY-SURFACE LAPLACIAN MAPPING OF CARDIAC EXCITATION IN INTACT PIGS

Relating body surface electrocardiographic signals to regional myocard ial events has been a major effort in cardiac electrophysiology. Conve ntional electrocardiographic means do not provide sufficient spatial r esolution to resolve distributed cardiac electrical activity. The purp ose of this investigation was to evaluate and study the validity of a new technique-body surface Laplacian mapping-in a well-controlled expe rimental setting, and to test the hypothesis that the body surface Lap lacian map (BSLM) can resolve normal and abnormal ventricular depolari zation patterns and localize the initial site of ventricular depolariz ation with high spatial resolution. In this study, BSLMs were construc ted from direct measurements of the surface Laplacian of the body surf ace potentials using an array of 64 concentric bipolar Laplacian elect rodes. BSLMs were compared to body surface potential maps (BSPMs) duri ng normal and ectopic ventricular activation in intact anesthetized pi gs. The BSLM displayed highly localized images of cardiac electrical a ctivity, indicating its ability to resolve myocardial events. The BSLM in pigs identified the pacemaking focus overlying the known location of the epicardial pacing electrode, and imaged the activation sequence associated with exogenous ventricular pacing. In contrast, in all cas es the BSPM revealed a diffuse distribution of activity over the chest . The present results suggest that the BSLM provides sufficient spatia l resolution to relate body surface recordings to regional myocardial events and is able to detect ventricular depolarization patterns with greater resolution than the conventional BSPM.