Catheter ablation of multiple accessory pathways in Ebstein anomaly guided by intracardiac echocardiography.

A 24-year-old-female with Ebstein anomaly, pre-excitation (ECG#1), and history of syncope was referred for catheter ablation. The procedure was guided by fluoroscopy, electro-anatomical mapping system (CARTO 3TM, Biosense-Webster), and intracardiac echocardiography (ICE) (Acunav, Siemens). At first, ICE (upper Panel) was used to define the true location of tricuspid annulus (TA) by course of the right coronary artery (RCA). Both anatomical and functional insertions of the tricuspid valve were then annotated (lower Panel shows right atrium in left anterior oblique and caudal view). Subsequently, the earliest ventricular activity during sinus rhythm was mapped to the posterolateral portion of TA. After delivery of radiofrequency (RF) current at that site, a small change in pre-excitation pattern (ECG#2) was noted and the earliest ventricular activation shifted more septally. Further RF lesions were deployed along the posterior and subsequently towards posteroseptal part of the TA, leading to gradual elimination (ECG#3) of conduction via the accessory pathways (APs) (dark red points in lower Panel). This observation is consistent with very broad width of the APs or with the presence of several APs located in close vicinity to each other. During follow-up of 1 year, the patient was without any symptoms and her ECG did not reveal any signs of pre-excitation. In general, overall long-term success rate in RF ablation of right-sided APs in patients with Ebstein anomaly is lower when compared with subjects without this anomaly. Poorer outcomes are mostly attributed to the presence of broad/ multiple APs caused by faulty