The Double Fire Phenomenon With Alternating Right Bundle Aberrancy

The AV node is a complex structure with multiple outputs into the atria and ventricles, which allows for arrhythmias with multiple patterns of atrial and ventricular relationships.

A patient with supraventricular tachycardias received ablation for both typical AVNRT through slow pathway modification and orthodromic reciprocating tachycardia through left posteroseptal accessory pathway ablation. Despite this, she continued to have episodes of tachycardia that were symptomatic. Repeat 12-lead ECG demonstrated a regularly irregular tachycardia with both narrow and wide complexes. An electrophysiology study was performed and showed sinus rhythm with dual AV nodal physiology with conduction down both the fast and slow pathways, resulting in double ventricular responses to a single atrial impulse. Additional slow pathway modification was performed, and no further arrhythmias were noted.

Dual AV nodal non-reentrant tachycardia is an uncommon arrhythmia that can occur in patients with dual AV nodal physiology, particularly after slow pathway modification for AVNRT.

Careful evaluation of P wave to QRS relationships on ECG can help elucidate complex patterns of arrhythmia Dual AV nodal non-reentrant tachycardia is an uncommon arrhythmia that can occur in patients with dual AV nodal physiology, particularly after slow pathway modification for AV nodal reentrant tachycardia.