Lower-loop reentrant atrial flutter

The mechanism of typical atrial flutter [AFL] has been well established. The isthmus between the tricuspid annulus and Eustachian ridge has been recognized as a critical part for maintaining the typical AFL circuit and the target site for ablation. However, a subtype of AFL, as double-wave reentry [lower loop reentry], has been described. This arrhythmia is due to the presence of 2 activation wavefronts rotating simultaneously. In this case report, we presented a case of counter-clockwise AFL with such activation circuit