Intracardiac and extracardiac potential distributions during ventricular ectopic beats

The authors measured and displayed three-dimensional potential distributions and wavefront configurations in the thickness of the left ventricular wall of isolated dog hearts immersed in a cylindrical or torso-shaped tank. They also determined the potential distribution in the extracardiac conducting volume. The results are consistent with the predictions of the oblique dipole layer model of the excitation wavefront. Currents flowing from the wavefront toward the resting tissue were generated exclusively by the portions of the wavefront that spread along fibers, except when the wavefront area propagating across fibers was very large compared to the portion spreading along fibers. The presence of insulating boundaries strongly affected the distribution of positive and negative areas around the wavefront