Noncontact endocardial map during sinus rhythm

The sequence of isopotential maps of the left ventricular endocardium (purple) is modeled to the ventricular chamber dimensions. The location of the multielectrode array is represented by the orange ellipsoid. Surface ECG lead I and selected virtual electrograms from a line following fascicular activation are shown beneath each map. Initial activation (arrow, panel A) occurs in the upper part of the fascicles and then progresses toward the apex (arrow, panel B). At the apex, fascicular activation initiates ventricular activation (white area, panel C).