Bundle branch re-entry ventricular tachycardia mimicking outflow-tract tachycardia: a case report

Figures

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  Figure 1. (A) Electrocardiograms of the patient’s baseline sinus rhythm (sinus cycle length 746 ms, PR interval 152 ms, QRS 88 ms, QT interval 418 ms, incomplete right bundle branch block). (B) Ventricular tachycardia with left bundle branch morphology and inferior axis (tachycardia cycle length 260 ms). ms = milliseconds.

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  Figure 2. (A) A discrete His potential was consistently recorded before each QRS complex on DEC 1–2 (DECANAV mapping catheter at His region). Importantly, beat-to-beat changes in the His–His interval preceded and predicted the subsequent ventricular–ventricular interval. (B) HV interval 51 ms during sinus rhythm. HV = His-ventricular; ms = milliseconds.

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  Figure 3. Right ventricular activation map during bundle branch re-entrant ventricular tachycardia. The red-coloured region (yellow triangle) located at the right ventricular sub-RVOT anteroseptum represents the earliest ventricular breakout site, which preceded activation at the right ventricular apical region. Red ablation tags indicate radiofrequency applications delivered along the presumed right bundle branch course from the mid-septal region towards the right ventricular apex. The solid yellow arrow indicates the right bundle branch potential, whereas the dashed yellow arrow indicates the His bundle potential. RVOT = right ventricular outflow tract.

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  Figure 4. Right ventricular apical entrainment showing post-pacing interval minus tachycardia cycle length of 28 ms, indicating that it is within the circuit. ms = milliseconds.

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  Figure 5. (A) Twelve-lead electrocardiogram recorded after right bundle branch (RBB) ablation, showing complete right bundle branch block (RBBB) with prolongation of the QRS duration to 136 ms. (B) Schematic illustration of the proposed bundle branch re-entry circuit on the three-dimensional right ventricular geometry: antegrade conduction down the RBB (solid red arrow) with ventricular breakout at the sub–right ventricular outflow tract (RVOT) antero-septal region via a septal branch, slow distal-RBB conduction towards the right ventricular apex (dashed red arrow), transseptal conduction (blue arrow), and retrograde conduction up the left bundle branch (LBB, green arrow) returning to the His bundle.