Figure 3.
Changes in atrial activation sequence at onset of ablation, with atrial electrogram (red arrow) on ablation catheter (Abldistal) now widely separated from the ventricular electrogram. Earliest atrial activation is now seen on the His catheter, suggesting retrograde atrial activation through the AV node, while accessory pathway potentials (black arrows) seen on the ablation catheter prior to onset of ablation are no longer present. Pacing was performed with the high right atrium catheter in the left ventricle.