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Figure 1 Propagation maps during typical atrial flutter (AFL) and upper loop re-entry (ULR). The non-contact mapping in Case 6 is displayed. (A) The propagation map of typical AFL in the right posterolateral view is shown on the left. The unipolar virtual electrograms are shown on the right. During clockwise typical AFL, the activation wavefront descends in the right atrium (RA) posterior wall and septum (a to c), travels through the cavotricuspid isthmus (not shown), and ascends in the RA anterior and lateral walls (d to f). Virtual electrograms along the crista terminalis (CT) show double potentials resulting from different wavefront propagation direction on each side of the CT. (B) The propagation map of ULR in the same patient is shown. The activation wavefront propagates down in the posterior RA (a to b), crosses a conduction gap in the CT (b to c), proceeds upward in the anterolateral RA, and turns around the superior vena cava (c to d) to complete the re-entrant circuit (d to a). Virtual electrograms (Virtual 9) on the CT show low amplitude potential between the first and second deflection, suggesting the presence of a conduction gap. IVC = inferior vena cava; SVC = superior vena cava.
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