Noninvasive electrocardiographic imaging (ECGI) of epicardial activation before and after catheter ablation of the accessory pathway in a patient with Ebstein anomaly

Abstract

Ebstein’s anomaly (1) is characterized by abnormal development of the tricuspid valve with the septal (and often posterior) leaflets of the valve displaced into the right ventricle (RV). The abnormal development of the tricuspid valve is often associated with several conduction abnormalities, including delayed intra-atrial conduction, right bundle branch block (RBBB) (2, 3), and ventricular pre-excitation (4). Absence of a RBBB pattern during sinus rhythm on a baseline ECG suggests the presence of an atrio-ventricular accessory pathway (AP) in patients with Ebstein’s anomaly. Often, successful catheter ablation of an AP results in a complete or partial RBBB pattern on the post-ablation 12-lead ECG in 94% of cases (5). However, changes in the activation of the heart following a successful catheter ablation of AP in a patient with Ebstein’s anomaly have never been studied with epicardial activation imaging techniques. Electrocardiographic imaging (ECGI) (6, 7) is a novel noninvasive imaging modality for cardiac electrophysiology. ECGI can image cardiac activity on the epicardial surface of the heart from body-surface potentials measured with 250 electrodes together with heart-torso anatomic information obtained from a thoracic ECG-gated CT. It has been validated with intra-operative mapping data in humans (8). It has also been applied in humans to image the electrophysiologic substrate and cardiac excitation under normal and various pathophysiologic conditions (6–11).