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Figure 4 Induction of AF by PV Stimulation

Tracing illustrating the approach of programmed stimulation in a pulmonary vein (PV) after the presence of atrial fibrillation (AF). The first baseline stimulus induces AF with a markedly shorter AF cycle length in the vein as compared with the atria. Of note, the first baseline stimulus is responded by a normal PV potential. After a delay of 150 ms, a "PV echobeat" (indicated by an asterisk) from the same vein occurred with a precocity of 180 ms and 205 ms to the following CS and HRA potential, respectively, that starts AF in the vein. Abbreviations as in Figure 2.