Intracardiac electrogram during ablation of Mahaim fiber tachycardia

Top panel shows surface leads I and V1 and intracardiac recordings from the right ventricular apex (RVA), His-bundle (HBE), and a mapping catheter (MaP) located at the tricuspid annulus. A Mahaim potential (M) is seen in the MaP recording, located between the atrial (A) and ventricular (V) electrogram. In bottom panel, radiofrequency current is applied at the site of the M potential, resulting in loss of Mahaim conduction and termination of the tachycardia.