Shift of exit site during ablation of ventricular tachycardia originating from the vicinity of left ventricular summit.

Shift of Exit Site During Ablation A 44-year-old man with structurally normal heart underwent catheter ablation of left ventricular summit tachycardia. The initial mapping revealed the origin of tachycardia at the junction of great cardiac vein and anterior interventricular vein. During ablation the exit site shifted to the nearby regions, which was recognized by subtle changes of 12-lead ECG. Mapping and ablating at different exit sites rendered the tachycardia noninducible.