Fig. 2

IPM in a healthy volunteer during sinus rhythm. The left panel a depicts the IPM at the start of the atrial depolarization (P wave) and the right panel b depicts the IPM at the start of the ventricular depolarization (QRS). The first point of atrial activation is observed near the entrance of the Superior Vena Cave (white arrow) into the Right Atrium. The first point of ventricular epicardial breakthrough is observed at the RV free wall (white arrow) at the site of the moderator band