Figure 11b

Final radiofrequency (RF) application at the bottom of the left superior pulmonary vein (LSPV) ostium eliminates all pulmonary vein (PV) potentials.
A fractionated continuium (gap eletrogram) is noted at the ostium, and on mapping more distally, a double PV potential appears between the atrial and ventricular electrograms (right panel, lower tracing).
Ablation eliminates all evidence of PV electrical conduction, as shown in the corresponding electrocardiogram recorded from the same sites after ablation (left panel) with local PV potentials dissociated at a slow rate.

Reference:Haissaguerre , M. and others,Catheter ablation of chronic atrial fibrillation targeting the reinitiating triggers,J.Cardiovasc. Electrophysiol.2000;1112-10).