How to ablate typical atrial flutter.

Typical atrial flutter, as referred to in this article, includes both the counterclockwise and the clockwise form of cavotricuspid isthmus-dependent right atrial flutter. The counterclockwise form is the most common and characterized by a stereotypical surface ECG pattern showing negative sawtooth flutter waves in II, III and aVF at a rate between 200–350 beats.min. This surface ECG morphology of counterclockwise typical flutter is remarkably consistent, allowing assumptions about the circuit being entirely within the right atrium and obligatory activation through the cavotricuspid isthmus. However, in contrast, the surface ECG morphology of clockwise flutter is more variable and difficult to distinguish from non-isthmus-dependent flutters. As a result, intracardiac activation mapping and entrainment mapping is often necessary as confirmation. Importantly, since both the clockwise and the counterclockwise forms share the same obligatory cavotricuspid isthmus, a common strategy of ablation is clearly applicable and has been shown to be effective.