Interatrial electrical dissociation with concealed atypical atrial flutter during catheter ablation

A 69-year-old man with a prior history of mitral valvuloplasty and recurrent symptomatic multidrug-resistant atypical atrial flutter (AFL) was referred to our institute for a third catheter ablation procedure after previous atrial fibrillation and typical AFL ablation procedure. The electrophysiological study documented a macroreentry circuit with a critical isthmus between the upper septal scar and the mitral annulus. Subsequent radiofrequency ablation in this region interrupted the arrhythmia. After burst pacing, an atypical AFL with 300 ms atrial cycle was induced. The electroanatomical mapping showed a complex activation circuit with a critical isthmus along the previous atriotomy scar between the prior ablation line and the upper right pulmonary vein. Subsequently, further radiofrequency was delivered between these two points finally documenting interatrial electrical dissociation IED with normal sinus rhythm NSR in the right atrium and most parts of the interatrial septum while AFL persisted in the left atrium (Figure). To note, left AFL during IED was concealed at the surface ECG. Further radiofrequency delivered on left atrial ridge interrupted the arrhythmia and restored regular interatrial conduction. Interestingly, incremental pacing from the distal coronary sinus was able to activate the left but not the right atrium, conversely, incremental pacing from the right atrium was regularly transmitted to the left atrium up to 75 b.p.m.

Source: Europace - January 5, 2021 Category: Cardiology Source Type: research