Twelve-leads electrocardiogram during the HFS.
Intracardiac recordings before and during the HFS. Ventricular
potentials were noticeable at the distal bipolar electrode of the
ablation catheter.
C . Trial pacing 10 seconds before the HFS. Pacing from the
ablation catheter at 150 beats per minute did not capture the
ventricular myocardium except for the initial three stimuli.