title: High resolution magnetic images of planar wave fronts reveal bidomain properties of cardiac tissue.
abstract: We magnetically imaged the magnetic action field and optically imaged the transmembrane potentials generated by planar wavefronts on the surface of the left ventricular wall of Langendorff-perfused isolated rabbit hearts. The magnetic action field images were used to produce a time series of two-dimensional action current maps. Overlaying epifluorescent images allowed us to identify a net current along the wavefront and perpendicular to gradients in the transmembrane potential. This is in contrast to a traditional uniform double-layer model where the net current flows along the gradient in the transmembrane potential. Our findings are supported by numerical simulations that treat cardiac tissue as a bidomain with unequal anisotropies in the intra- and extracellular spaces. Our measurements reveal the anisotropic bidomain nature of cardiac tissue during plane wave propagation. These bidomain effects play an important role in the generation of the whole-heart magnetocardiogram and cannot be ignored.
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37325, USA.
authors.forename: Jenny R
authors.initials: JR
authors.lastname: Holzer
authors.forename: Luis E
authors.initials: LE
authors.lastname: Fong
authors.forename: Veniamin Y
authors.initials: VY
authors.lastname: Sidorov
authors.forename: John P
authors.initials: JP
authors.lastname: Wikswo
authors.forename: Franz
authors.initials: F
authors.lastname: Baudenbacher
mesh_terms: D000818:Animals; D018780:Body Surface Potential Mapping / Q000379:methods*; D006329:Heart Conduction System / Q000502:physiology* / Q000648:ultrastructure; D006352:Heart Ventricles / Q000166:cytology*; D008280:Magnetics; D008564:Membrane Potentials / Q000502:physiology*; D011817:Rabbits; D016276:Ventricular Function