Background: Congenital anomalous connection between the right atrial appendage (RAA) and right ventricle (RV) is a rare accessory atrio-ventricular pathway that can be difficult to map and may require epicardial or surgical ablation to eliminate conduction.
Objective: To describe our experience with mapping and ablation of this rare accessory pathway.
Methods: We retrospectively analyzed the prevalence of RAA-RV connections in 148 consecutive patients who underwent endocardial ablation of right sided accessory A-V pathways. Three out of 148 patients (2%, 2 women) had antegrade and retrograde conduction between the RAA and the RV. All 3 patients suffered from recurrent orthodromic A-V reentrant tachycardias and were referred after 1-2 previously failed ablations. None of these patients had evidence of an additional congenital anomaly. Mapping was performed using the Carto system with direct visualization of the right atrium, tricuspid annulus, and RAA using intracardiac echocardiography (Figure, A).
Results: The successful ablation site in these 3 patients was located in the floor of the RAA above the base of the RV (Fig A, black dotted lines). Local ventricular electrogram preceded the delta wave by 30-40 msec (Figure B, arrow) and conduction was eliminated using external irrigated electrode catheters (20-30 watts).
Conclusion: Accessory atrioventricular pathways due to congenital connection between the RAA and RV should be suspected when mapping and ablation along the tricuspid annulus fails to eliminate conduction. The use of intracardiac echocardiography facilitates the identification of the location of the mapping catheter within the RAA at the successful ablation site.