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Figure 6 Spontaneous Onset of Atrial Flutter in a Patient

(Top panel) The ECG lead II recorded simultaneously with bipolar A_EGs from the sulcus terminalis and Bachmann’s bundle. The * indicates a premature atrial beat that induces type II AFL (rate of 390 beats/min), which in turn causes AF (see ECG) due, we suggest, to fibrillatory conduction. (Bottom panel) The tracings are continuous with the top panel. Type II AFL persists in the A_EGs, as does AF in the ECG, until AFL abruptly develops (*). We suggest that during the period of AF generated by the type II AFL, the functional components of the typical AFL re-entrant circuit evolved. Time lines at 1-s intervals. BB_EG = electrogram from the Bachmann’s bundle; ST_EG = electrogram from the sulcus terminalis; other abbreviations as in Figure 5. Reprinted, with permission, from Waldo and Cooper (6).