Oblique Propagation of Activation Allows the Detection of Uncoupling Microstructures from Cardiac Near Field Behavior

Wave fronts of cardiac activation, when propagating oblique to the fiber axis, reveal small fractionations and distortions in extracellular potential waveforms Phi_e as well as in parameters derived from Phi_e like dPhi_e/d_t and the gradient of Phi_e, the cardiac near field E. dPhi_e/d_t shows multiple deflections and E changes its morphology forming abnormal or even two or multiple subsequent loops. We analyze segments of such irregular loops of E obtained from in-vitro experiments and from computer simulation of a 2D-tissue sheet with a longitudinal oriented obstacle. In computer simulations we found that the individual sections of E reflect fairly well individual pathways of activation separated and delayed by the presence of a structural obstacle similar to connective tissue embedded longitudinally in heart tissue. Electrophysiological experiments with papillary muscles confirm this near field behavior.