Abstract 2471: Epicardial-side Conduction During Cavotricuspid Isthmus Ablation; Prevalence, Significance, and a Novel Sign ‘Sigmoid Pattern’ of Halo Catheter on the Tricuspid Annulus
Background: Radiofrequency (RF) ablation of cavotricuspid isthmus (CTI) in patients with common atrial flutter is well established. However, difficulties in the creation of the block line can be encountered. Some reports referred to the epicardial-side conduction caused the difficulties.
Purpose: We investigated the prevalence, significance, and electrophysiological features of the epicardial-side conduction in the course of CTI ablation utilizing a non-contact mapping system (NCM).
Methods: Subjects consisted of 76 patients with CTI-dependent atrial flutter who underwent CTI ablation using NCM. After producing one linear lesion, we analyzed activation patterns of the right atrium (RA) during coronary sinus pacing with NCM, also with activation sequence of halo catheter on tricuspid annulus. The epicardial-side conduction was defined based on breakout pattern in low lateral RA on NCM.
Results: In the course of CTI ablation procedure, 46 patients (61%) presented epicardial-side conduction. Bidirectional block in CTI was achieved in all but 2 patients with epicardial-side conduction. Number of radiofrequency application was significantly greater in patients who presented epicardial-side conduction than patients who did not (9.6 +/− 5.9 vs. 17.2 +/− 10.3, p<0.01). The halo catheter demonstrated sigmoid pattern in 18 patients (78.3%) with polarity reversal (Figure⇓) among 23 examined patients with epicardial-side conduction.
Conclusion: The epicardial-side conduction presented with high prevalence, caused difficulties in CTI ablation. In many cases, the epicardial-side conduction during CTI ablation was confirmed with the halo catheter on tricuspid annulus.