BUNDLE-BRANCH REENTRY VENTRICULAR-TACHYCARDIA - AN INVESTIGATION OF THE CIRCUIT WITH RESETTING

We describe a patient with bundle branch reentry ventricular tachycard ia with 1:1 VA conduction in whom resetting was performed while obtain ing simultaneous recordings from the right ventricular apex (V) and Hi s-bundle electrogram. Both the tachycardia return cycle and the V-His interval demonstrated an increasing reset response, while the His-V in terval demonstrated a flat reset response. These reset responses are c onsistent with a partially excitable gap localizing to the V-His porti on of the bundle branch reentry circuit.