Hybrid epicardial and endocardial ablation of a persistent atrial tachycardia arising from the marshall bundle: the importance of a detailed analysis of the local potentials.

Radiofrequency catheter ablation of an atrial tachycardia (AT) and atrial fibrillation (AF) was performed in a patient with a history of pulmonary vein isolation for paroxysmal AF. The AT exhibited a centrifugal pattern with the posterolateral LA as the earliest activation site. The AT was not terminated by ablation at the endocardial earliest site, but its cycle length was prolonged by ablation at an opposite site within the Vein of Marshall. Finally, the AT was terminated by an energy application at a site 7 mm posteroinferior to the initial earliest activation site. We analyzed the local potentials of each energy delivery site in detail.