Figure legends:
Figure 1: Twelve lead electrocardiogram of the clinical arrhythmia demonstrating wide complex tachycardia of LBBB morphology at a rate of 200bpm.
Figure 2A: Induction of LBBB tachycardia by incremental CS pacing following AH prolongation and HV shortening. Note that the last 4 paced beats are non-captured beats during LBBB tachycardia. CS 1,2: distal coronary sinus; CS 9,10: proximal coronary sinus; His d: distal His bundle. His p: proximal His bundle. HRA: high right atrium. H: His deflection.
Figure 2B: Atrial extra-stimuli (arrow) during His refractoriness. Baseline tachycardia cycle length is 310ms. His deflection is marked on the distal His channel as H. The atrial electrogram is marked as A and the ventricular electrogram as V. CS 1,2: distal coronary sinus; CS 9,10: proximal coronary sinus; His d: distal His bundle. His p: proximal His bundle. RV: Right ventricle.
Figure 3A: Wide complex tachycardia at a CL of 348ms. Ablation catheter is placed at the ablation site. 3B : CS pacing at 280ms after successful ablation. A: Atrium, V: Ventricle. CS 1,2: distal coronary sinus; CS 9,10: proximal coronary sinus; ABL d: distal ablation; ABL p: proximal ablation.