Electro-anatomical characterization by cardiac electric near-fields

Pathways, contours of wavefronts and velocity of cardiac conduction are the essential parameters to study normal and abnormal excitation spread. Apart from very elaborated endocardial multi-electrode mapping systems used to compute the patterns of activation we propose to measure the electric field intracardially in the close vicinity of the cardiac tissue. Specifically in regions of complex structures of conduction like in the atrium by this method we can obtain parameters of the very local process of excitation spread. We studied the case of continuous anisotropic conduction, complex propagation in fibrotic tissue as well as the case of branching structures in macroscopic dimensions. Electrophysiologic experiments, structural analysis of the tissue and computer models of excitation spread were put together to clarify how gross-anatomy and micro-architecture of heart tissue affects the behavior of the near-field during depolarization. The power of computer-models to define clearly structures (unpredictable in real tissue during the experiment) enabled us to classify and differentiate effects of cardiac structure on extracellular potentials and near-fields. In the future field-sensors could be built in catheters as a navigation-tool identifying complex pathways of conduction or to assess conduction patterns modified by intracardiac ablation procedures.