“…1, Panel 1): this is detected if an electrode is positioned within the small zone where antidromic penetration changes. 8,20 The criterion presented here is applied to overdrive pacing at different sites, and also relies upon a change in the position of the collision line. A potential disadvantage with the present criterion is that overdrive pacing must be stopped, tachycardia allowed to resume, and then another overdrive pacing maneuver performed from a second site.…”