Narrow-QRS Ventricular Tachycardia Due to Microreentry After Iatrogenic Right Bundle Injury
Myoung Jung Kim1, Wonyoung Jung1, Juwon Kim1
1Division of Cardiology, Department of Internal Medicine, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
Background:
Ventricular tachycardia (VT) after ablation near the conduction system can present with a relatively narrow QRS complex and mimic supraventricular tachycardia (SVT), making diagnosis and management challenging.
Case Summary:
A 26-year-old man with 2 prior ablations for idiopathic premature ventricular complexes presented with incessant narrow-QRS tachycardia and left ventricular systolic dysfunction. Despite antiarrhythmic drugs and repeated cardioversion, the tachycardia persisted. Electrophysiologic study demonstrated ventriculoatrial dissociation, fixed His-His return intervals, and concealed fusion during atrial overdrive pacing. High-density mapping identified earliest activation at the mid-right bundle within a voltage border zone. Targeted radiofrequency ablation at this site terminated the VT and restored sinus rhythm, with complete recovery of ventricular function.
Discussion:
This case illustrates an iatrogenic conduction system-related microreentrant VT masquerading as SVT, and it highlights the value of pacing maneuvers and high-density mapping for mechanistic diagnosis and precise ablation.
Take-Home Messages:
VT after prior right ventricular ablation may present with a narrow-QRS complex and mimic SVT. High-density mapping and pacing maneuvers can reveal an iatrogenic conduction system-related reentrant circuit and guide effective ablation.
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