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Figure 1 Three-dimensional left atrial (LA) voltage maps (posteroanterior view: left, preablation; right, postablation), depicting peak-to-peak bipolar electrogram amplitude. Color red represents lowest voltage, and purple, highest voltage. Claret red spheres represent radiofrequency lesions. In postablation, areas within and around the ablation lines, involving to some extent the LA posterior wall, show low-amplitude (<0.1 mV) electrograms. Preablation insets show pulmonary vein (PV) ostial potentials indicating the activation of muscular fibers capable of conducting impulses in or out of the veins. By creation of lesions around each vein ostium, PV potentials are no longer detected (insets) at the same ostial points recorded before ablation. LSPV = left superior pulmonary vein; LIPV = left inferior pulmonary vein; RSPV = right superior pulmonary vein; RIPV = right inferior pulmonary vein.