AVNRT With Intermittent Aberrancy-Mimicking Ventricular Tachycardia: One Tachycardia, Two QRS Morphologies
Vineet Madishetty1, Badal Sojitra1, Vincent Sachs1
1Internal Medicine/Cardiology, HCA Healthcare/USF Morsani College of Medicine GME/Largo Medical Center, Largo, Florida, USA.
Background:
Regular wide-complex tachycardia often prompts concern for ventricular tachycardia, yet supraventricular tachycardia with aberrancy is a frequent mimic.
Case Summary:
A 36-year-old male presented with palpitations, dizziness, and presyncope after ambulatory monitoring documented tachycardia >200 beats/min. Telemetry showed recurrent regular tachycardia with alternating narrow and wide QRS morphologies at a similar cycle length. Vagal maneuvers, adenosine, and diltiazem transiently slowed/terminated the rhythm, but it recurred, necessitating cardioversion. Electrophysiology study induced typical atrioventricular nodal re-entrant tachycardia with rate-dependent aberrancy; slow-pathway ablation rendered the tachycardia noninducible.
Discussion:
Unchanged cycle length during narrow-to-wide transitions supports a single supraventricular tachycardia mechanism with a functional bundle branch block.
Take-Home Message:
When QRS morphology alternates without cycle-length change, suspect supraventricular tachycardia with aberrancy and confirm with electrophysiology testing.
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