A) 1.5-second example of dV/dt, with box highlighting the individual beat displayed in B) B, PF (yellow) to WVM (red) pattern. A rapidly propagating Purkinje wave front enters the top aspect of the array and propagates to the bottom left, stimulating a PF-WVM junction, after which an expanding Purkinje ring of activation appears, followed by a more slowly activating ring of ventricular myocardium. Temporal derivatives of the labeled electrode recordings are shown. Reprinted with permission.40