ABSTRACT
Atrial flutter is a macro-reentrant atrial tachycardia that propagates around an obstacle, regardless of the atrial cycle length. Atypical Atrial flutter are an heterogeneous group of Atrial flutter, more often associated with structural heart diseases or previous surgical and/or ablation procedures. The ability to identify the macro-reentrant circuit by activation mapping with consequent reliable elimination of its critical isthmus makes radiofrequency ablation of Atrial flutter a safe and curative with >90% long-term success rate. RA atypical flutters are usually associated with prior atrial surgery or after radiofrequency ablation, but scar can be found also in patients without prior cardiac interventions, usually with a posterolateral or lateral distribution. An exception is upper loop re-entry, in which the circuit is around the SVC with crista terminalis serving as the area of slow conduction.
