Atrial Tachycardia and Bundle Branch Re-Entry Ventricular Tachycardia With Similar QRS Complex Morphology

Figures

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  Figure 1. ⁠Baseline Electrocardiogram During Nonsustained and Sustained Tachycardia (A) 12-lead electrocardiogram obtained in the emergency department shows sinus rhythm with right bundle branch block morphology and initiation of wide-QRS-complex tachycardia. The tachycardia is initiated by an atrial premature beat (asterisk), and the right bundle branch block QRS complex morphology of the tachycardia is identical to that of sinus rhythm after initial, transient aggravation of intraventricular conduction delay in the first 5 beats; and (B) 12-lead electrocardiogram obtained at a referring hospital shows wide-QRS-complex tachycardia with QRS morphology nearly indistinguishable from atrial tachycardia in panel (A). Despite a similar electrocardiogram appearance, beat-by-beat alternation in T-wave morphology (aVL) suggests 2:1 ventriculoatrial conduction block (arrows), which is not compatible with atrial tachycardia.

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  Figure 2. Electrocardiogram QRS Complex of Sinus Rhythm, Atrial Tachycardia, and Ventricular Tachycardia During Electrophysiologic Study (A) Electrocardiogram obtained during electrophysiologic study shows a sinus rhythm with right bundle branch block QRS complex; (B) programmed electrical stimulation induced 2 types of supraventricular tachycardia, and 1 ventricular tachycardia. Mapping of the supraventricular tachycardia revealed a macrore-entry around the mid-to-lower crista terminalis, and focal atrial tachycardia originating from the coronary sinus; and (C) atrial or ventricular overdrive pacing also induced a wide-QRS-complex tachycardia with similar QRS complex morphology but ventriculoatrial dissociation. The mechanism was bundle branch re-entry ventricular tachycardia. The QRS complexes of the sinus rhythm, atrial tachycardia, and ventricular tachycardia were almost identical.

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  Figure 3. Mapping of the Supraventricular Tachycardia (A) During electrophysiologic study, voltage mapping of the right atrium showed a large scar in the posterior wall of the right atrium (sinus venosus) near the inferior vena cava; activation mapping revealed a clockwise macrore-entry located at the mid-to-low crista terminalis, where radiofrequency lesion through the lower crista terminalis rendered the tachycardia noninducible. (B) After these linear lesions, another supraventricular tachycardia was induced, and the earliest activation was mapped at the ostium of the coronary sinus, which was also eliminated by focal ablation at the tachycardia focus.

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  Figure 4. Intracardiac Electrogram and Entrainment Mapping of Ventricular Tachycardia Simultaneous surface electrocardiogram and intracardiac electrograms demonstrating 1:1 His-ventricular coupling and prolonged HV interval (145 ms, red asterisk, ABLd) during tachycardia. Ablation catheter was placed at the His bundle recording area, and a DECA was positioned at the left ventricular septum with proximal (DECA 9.10) pole at the high and distal (DECA 1,2 or 3,4) pole at the midseptum. Activation of the left bundle branch from high to midseptal direction (blue asterisk and arrow) preceding ventricular activation suggested a reverse-type bundle branch re-entry. Overdrive pacing from the left septal region (DECA 3,4) at a pacing cycle length of 290 ms yielded a postpacing interval of 326 ms, which was identical to that of tachycardia cycle length (326 ms). ABLd = distal ablation electrode; DECA = decapolar catheter.

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  Visual Summary. Electrocardiogram Mimic of Bundle Branch Re-Entry Ventricular Tachycardia Atrial tachycardia and reverse-type bundle branch re-entry ventricular tachycardia share nearly identical surface electrocardiographic morphology despite completely different mechanisms, prognoses, and therapeutic implications.