Atrioventricular Ring Tachycardias: Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia and Atrial Tachycardia Share a Common Arrhythmogenic Substrate-A Unifying Proposal

Two Distinct Atrial Breakthroughs During Fast-Slow Atrioventricular Nodal Reentrant Tachycardia

INTRODUCTION

The slow atrioventricular nodal pathway (SP) typically has a single atrial breakthrough site.

METHODS AND RESULTS

We report a case of fast-slow type AVNRT with two distinct atrial breakthrough sites during tachycardia. The earliest atrial activation site (EAAS) was at the right inferior septum, followed by the inferolateral wall of the tricuspid annulus. Ablation at the EAAS shifted it to the inferolateral wall.

CONCLUSION

This case demonstrates two distinct atrial breakthrough sites from a single SP in AVNRT.

Unusual left-sided variant orientation of the slow conduction zone in adenosine-sensitive atrial tachycardia

Adenosine-sensitive atrial tachycardia (AT) is typically associated with a slow conduction zone (SCZ) near the atrioventricular node or tricuspid annulus. We report an unusual case of adenosine-sensitive AT with a SCZ located between the left atrial appendage and the left atrial anterior septum, which was successfully ablated 9.2 mm from the left atrial earliest activation site. This case highlights the importance of advanced mapping and entrainment techniques in the identification and management of rare left-sided SCZ variants of adenosine-sensitive AT.

Electroanatomical Mapping System-Guided vs. Intracardiac Echocardiography-Guided Slow Pathway Ablation: A Randomized, Single-Center Trial

Radiofrequency (RF) catheter ablation is an effective treatment option for targeting the slow pathway (SP) in atrioventricular nodal reentry tachycardia (AVNRT). Previous data suggested that using intracardiac echocardiography (ICE) guidance could improve procedural outcomes when compared to using fluoroscopy alone. In this prospective study, we aimed to compare the effectiveness of an electroanatomical mapping system (EAMS)-guided approach with an ICE-guided approach for SP ablation. Eighty patients undergoing SP ablation for AVNRT were randomly assigned to either the ICE-guided or EAMS-guided group. If the procedural endpoint was not achieved after 8 RF applications; patients were allowed to crossover to the ICE-guided group. The ICE-guided approach reduced the total procedure time (61.0 (56.0; 66.8) min vs. 71.5 (61.0; 80.8) min, p < 0.01). However, the total fluoroscopy time was shorter (0 (0-0) s vs. 83.5 (58.5-133.25) s, p < 0.001) and the radiation dose was lower (0 (0-0) mGy vs. 3.3 (2.0-4.7) mGy, p < 0.001) with EAMS-guidance. The ICE-guided group had a lower number of RF applications (4 (3-5) vs. 5 (3.0-7.8), p = 0.03) and total ablation time (98.5 (66.8-186) s vs. 136.5 (100.5-215.8) s, p = 0.02). Nine out of 40 patients (22.5%) in the EAMS-guided group crossed over to the ICE-guided group, and they were successfully treated with similar RF applications in terms of number, time, and energy compared to the ICE-guided group. There were no recurrences during the follow-up period. In conclusion, the utilization of ICE guidance during SP ablation has demonstrated notable reductions in procedural time and RF delivery when compared to procedures guided by EAMS. In challenging cases, an early switch to ICE-guided ablation may be the optimal choice for achieving successful treatment.