229-03: Radiofrequency Catheter Ablation at the Noncoronary Cusp for the Treatment of Parahisian Atrial Tachycardia

Abstract

Introduction: This study investigated radiofrequency ablation (RFA) of focal atrial tachycardia (AT) originating from the His bundle region. Methods: This study included 32 patients (22 females, age 58 + 12 years) with AT localising near the His bundle. Activation mapping of the right atrium (RA; n ¼ 32), left atrium (LA; n ¼ 16) and non-coronary cusp (NCC; n ¼ 26) was performed during AT to identify the earliest activation site. The site of successful RFA served as final confirmation of AT origin. Results: Mapping in the RA demonstrated that the earliest activation site was located at the His region. The earliest LA activation time, mapped at the anteroseptal part, was equal or preceded the His bundle region by 5.0 + 3.5 ms (ranging 0-10 ms) in 4 patients. Whereas the earliest activation in the NCC preceded the His bundle region by 7.4 + 7.0 ms (ranging 0-30 ms) in 26 patients. RFA successfully terminated AT in the NCC in 24/25 patients (96% success rate), in the RA in 3/8 patients (38% success rate) and in the LA in 4/13 patients (31% success rate). In 1 patient RFA failed in the both atria and NCC. AV block occurred in 4/8 (50%) cases during RFA in the RA (3 permanent and 1 transient 3rd degree AV block) and in 1/13 (8%) patients (transient 3rd degree AV block) during RFA in the LA. PR interval prolongation did not occur during RFA at the NCC in all patients ( Figure). All patients had no AT recurrence during a follow-up of 26 + 25 months. Conclusion: AT originating from His bundle region should be carefully mapped in both atria and NCC. In most of the cases this type of AT can be treated safely and effectively with RFA in the NCC. Purpose: Intracardiac echography (ICE) is used during radiofrequency ablation (RFA) of atrial fibrillation to reconstruct 3D electroanatomic maps of left atrium (LA) and to monitor potential complications, including esophageal injuries. In clinical practice, LA posterior wall (LAPW) contour is manually traced on ICE images and its distance from the esophagus only visually assessed. This tracing procedure is time-consuming and esophagus visual assessment does not allow quantitative evaluation of LAPW-esophagus relationship. The present study aimed to automatically detect esophagus position and its spatial relationship from the LAPW by ICE during RFA. Methods: An algorithm for LA segmentation was preliminary developed and validated to detect LAPW in ICE sequences. Once LAPW was detected, a fast algorithm based on the evaluation gray level intensity distribution in the image was developed to detect candidate pixels belonging to the esophagus wall. Simple second and forth order models were used for fitting resulting in distal and proximal esophagus contours, respectively. The algorithm was tested on 13 ICE acquisitions. In 13 images, one for each ICE sequence, detected esophagus boundaries were compared with manually traced (MT) ones by an experienced cardiologist. Mean esophagus thickness and the distance between esophagus proximal boundary and LAPW was also computed. Results: Mean an...