Figure 2.

A: An intracardiac electrogram of the roof vein demonstrated 2 components of the potentials: the first component was passively activated circumferential potentials and the second component was local firings without conduction to the left atrium (blocked firings, arrowheads). B: A single radiofrequency energy application eliminated the circumferential potentials in the roof vein. White arrowheads demonstrate the disappearance of the roof vein potentials during ablation, and black arrowheads indicate the continuously observed far-field electrograms in the superior vena cava.