Figure legend
Figure 1 A: Mild preexcitation with slightly shortened H-V interval (21ms) was observed at baseline. RVA was preceded by HIS. B: Atrial pacing and the extrastimulus resulted in minimal preexcitation and a fixed H-V interval during A-H prolongation, with activation of RVA remaining later than HIS. AP=accessory pathway; CS=coronary sinus; RVA=right ventricular apex.
Figure 2 A: After isoproterenol infusion, prominent delta wave was present with an H-V interval of -12ms. B: Wide complex tachycardia without anterograde His was induced, during which atrial overdrive pacing entrained the ventricles with identical QRS configuration and an A-V-A response following cessation. CS=coronary sinus; RVA=right ventricular apex.
Figure 3 A: 2 discrete AP potentials were recorded by ABLp. B: The interval from split pathway potentials to local V increased when the atrioventricular AP blocked spontaneously. C: Pulling back the catheter made both signals appearing on distal ABL. See text for discussion. ABL=ablation catheter; AP=accessory pathway; CS=coronary sinus; RVA=right ventricular apex.
Supplemental Figure: Accelerated rhythm with the identical QRS configuration to tachycardia was present due to enhanced pathway automaticity during radiofrequency. ABL=ablation catheter; CS=coronary sinus; RVA=right ventricular apex.