Supraventricular arrhythmia with discordant electrocardiographic features: What is the arrhythmia mechanism?

Junctional and AV nodal reentrant tachycardia share common electrocardiographic features, but they differ in their management and outcomes after catheter ablation. This case concerns a 60‐year‐old female who presented with recurrent episodes of a relatively slow, regular supraventricular arrhythmia. Electrocardiographic features of the arrhythmia were discordant regarding its underlying mechanism. However, careful analysis of 12‐lead electrocardiograms, with focus on the effect of spontaneous premature beats, pointed out the arrhythmia etiology. Electrophysiological study and pacing maneuvers defined the arrhythmic substrate that was successfully treated by catheter ablation.     

Pause-dependent mitral isthmus conduction block during ablation of the mitral isthmus: What is the mechanism?

Mitral isthmus (MI) ablation is commonly performed as an adjunct therapy to pulmonary isolation during the treatment for persistent atrial fibrillation. Confirmation of complete MI block is essential because an incomplete MI block may result in iatrogenic atrial tachycardia. However, there are several pitfalls in the diagnosis of an MI line block. We herein report a case of transient pause-dependent MI block during MI ablation.     

Supraventricular tachycardia with atrial activation earliest at the His bundle region—What is the mechanism?

A 70‐year‐old man with recurrent symptomatic supraventricular tachycardia was referred for catheter ablation. Atrial activation was earliest at the His bundle region with HA longer than AH.