Click on image to view larger version.

Figure 2 Activation of a focus leading to AF in patient 7 from just inside the left superior pulmonary vein (LSPV, HIS potential was of low amplitude). The first beat of the focus (*) was 58 ms (not labeled) ahead of the high RA electrogram. In this patient, decremental conduction occurred from the focus to the rest of the atrium, and advancement of CS electrograms compared to the sinus beat. At the ablation catheter, the atrial electrogram shows an initial rounded then a fast component during sinus rhythm, which appears to reverse and separate at the first beat of tachycardia. Abbreviations as in Figure 1. Each calibration mark on the left represents 1 mV for that and the following recordings until a change in calibration was made.