PC-577-01 FASCICULAR ECTOPY FROM THE RIGHT CORONARY SINUS OF VALSALVA

Abstract

Fascicular ectopic complexes (FEC) can cause symptoms and pseudo atrio-ventricular block (AVB). Ablation is a viable option but carries a risk of AVB. Successful far-field ablation of left anterior fascicular beats from right aortic sinus of Valsalva (RASoV) has been reported. We present a case of FEC with earliest HPS signal and successful ablation from the RASoV. N/A A 60-year-old woman had palpitations and blocked P waves. ECG revealed frequent FEC and occasional blocked P waves (fig. 1a). We postulated this to be due to concealed FEC (pseudo AVB). She failed flecainide and presented for ablation. A decapolar catheter was placed across the right His-Purkinje system (HPS). She had frequent FECs with early activation of the HPS. We observed FECs with complete antegrade block within the HPS but retrograde penetration into the atrium proving this as the mechanism for pseudo AVB (fig. 1b). Activation mapping of the right and left (retroaortic) HPS was performed with the earliest HPS potential on the decapolar catheter as the fiducial reference. Activation progressed retrograde to the proximal His and antegrade to the RBB, both being later than the distal His. Similarly, the left bundle branch and both fascicles were late. Mapping in the RASoV identified a His-like signal in sinus rhythm that was the earliest site in FEC, 7 ms ahead of reference (fig 1c & d). Focal radiofrequency ablation immediately abolished FECs. Monitoring overnight revealed no further FECs or blocked P waves, and patient reported relief of symptoms. Mapping of FEC should include the RASoV. The anatomic basis for such fascicular potential in the RASoV may be the dead-end tract of the conduction axis reported by Kurosawa and Becker.