Catheter ablation of accessory pathway tachycardias in three patients with Ebstein's anomaly

Ebstein's anomaly (EA) is a malformation of the tricuspid valve characterized by a downward displacement of the septal and often the posterior tricuspid valve leaflets to the atrialized right ventricle. Among all congenital anomalies, EA is the most related malformation with accessory pathways. In 5%-25% of patients with EA, accessory atrioventricular pathways may present on the surface electrocardiogram. Radiofrequency catheter ablation is the first-line treatment of EA patients having supraventricular tachyarrhythmias. The presence of a dysplastic tricuspid annulus and electrically distinguishable atrioventricular activity may complicate radiofrequency catheter ablation of accessory pathway tachycardia in these patients. We present three cases of EA in which accessory pathway tachycardias were successfully ablated, with emphasis on technical difficulties in electrophysiological diagnosis and during radiofrequency ablation.