Total activation mapping in a patient with an epicardial accessory pathway

A 42-year-old man was admitted for recurrent atrioventricular reciprocating tachycardia. We performed a total activation mapping, which included a range from the ventricular to atrial waves during right ventricular pacing. The mapping revealed a delayed ventriculoatrial conduction on the left lateral wall. We performed ablation within the coronary sinus, and the ventriculoatrial conduction was lost. By widening the range, we could easily visualize the ventriculoatrial conduction through the accessory pathway. This mapping showed that the conduction in the area of the accessory pathway was delayed, and it was easy to estimate that the conduction pathway included the coronary sinus.