The radio frequency catheter ablation of inter-fascicular reentrant tachycardia: new insights into the electrophysiological and anatomical characteristics

Transcatheter cryo-ablation of septal accessory pathways, multicenter observational study in Japan

BACKGROUND

Ablation using radiofrequency energy has to be carefully performed when the arrhythmia substrate is located in close proximity to the atrioventricular (AV) node due to the risk of inadvertent permanent AV block. The aim of this study was to evaluate the efficacy and safety of catheter-based cryo-therapy for septal accessory pathways (APs).

METHODS

A total of eleven patients (median = 56.3 years, range 13-74 years) with septal APs underwent cryoablation. Ice-mapping was performed during sinus rhythm and an AV reciprocating tachycardia utilizing the APs as a requisite limb with cooling of the catheter tip temperature to a maximum of -30℃ for less than 45 s. Cryo-ablation was performed for 4 min at a temperature of -80℃ only if ice-mapping abolished the pre-excitation or retrograde conduction over the AP without injury to the AV nodal conduction.

RESULTS

Cryo-ablation was acutely successful in all eleven patients. No permanent cryo-related complications or adverse outcomes were reported. During the follow-up (range 14-26 months), no patients experienced any arrhythmia recurrences.

CONCLUSION

Ice-mapping was a feasible and reliable method to determine the exact location of the APs owing to the possibility of validating the ablation site. Cryo-ablation of APs located near the AV junction is a safe and efficacious technique with a high success rate over the long term.

IRB INFORMATION

Ethical Committee of Japan Red Cross Yokohama City Bay Hospital #2018-19.

Cryofreezing catheter ablation of adenosine triphosphate sensitive atrial tachycardia

INTRODUCTION

Adenosine triphosphate (ATP) sensitive atrial tachycardia (AT) has been treated by radiofrequency catheter ablation. Cryofreezing energy has emerged as a novel energy source for catheter ablation. The aim of this study was to investigate the efficacy and safety of cryofreezing ablation for ATP-sensitive AT.

METHODS AND RESULTS

A total of six patients with ATP-sensitive ATs were included in this study. A single atrial extrastimulation was able to initiate and terminate these ATs in all six patients. The electrophysiological findings satisfied the diagnostic criteria of ATP-sensitive AT. The ablation catheter was located at the earliest activation site of atrial excitation during the AT, and cryofreezing energy was delivered through a cryoablation catheter to perform cryomapping at temperature of -30 or -80°C. When cryomapping successfully terminated the ATs, cryoablation at a temperature of -80°C was subsequently performed. The earliest atrial activation during AT was recorded at the Koch's triangle area associated with a distinct intra-atrial activation sequence from that recorded during ventricular pacing. Cryoablation was performed at successful cryomapping sites and resulted in the complete elimination of the AT in all six patients without affecting the bidirectional atrioventricular (AV) nodal conduction.

CONCLUSION

Cryofreezing energy was safe and effective in treating ATP-sensitive ATs even in patients with its origins located in the vicinity of the AV node.

Bidirectional Ventricular Tachycardia Due to a Mixture of Focal Fascicular Firing and Reentry

Bidirectional ventricular tachycardia (BDVT) is a well-known phenomenon since it was first described in 1922. Various mechanisms have been proposed for BDVT, including digitalis toxicity, hypokalemia, Anderson-Tawil syndrome, acute myocarditis, and catecholaminergic polymorphic ventricular tachycardia. It is characterized by rapid, wide complex electrocardiogram pattern with alternating QRS morphology and axis. The alternation of the QRS is usually right bundle branch block with 180° swings in the frontal plane axis or, less commonly, alternation of right bundle branch and left bundle branch forms. Most of the proposed mechanisms involve triggered activity or enhanced automaticity. We describe a unique BDVT, with characteristics of both re-entry and triggered activity, which terminated with a focal Rf lesion.