Catheter ablation of atrial flutter.

Typical atrial flutter in humans is the consequence of a stable macro-reentrant circuit produced by the unique right atrial architecture providing anatomic barriers and functional blocks to conduction. Mapping studies have indicated that the so-called isthmus between the inferior aspect of the tricuspid annulus and the ostium of the inferior caval vein is a critical zone for maintenance of atrial flutter. An anatomically guided approach with placement of a transmural and contiguous lesion line throughout the isthmus has established as curative treatment of typical atrial flutter. Electrophysical criteria indicating complete bidirectional isthmus conduction block after ablation proved to be superior with respect to redurrences of atrial flutter compared with the noninducibility criterion. The gold standard for prove of complete conduction block is the recording of double potentials along the entire isthmus ablation line. Recently, it proved possible to reduce the period of fluoroscopy during isthmus ablation by using electro-anatomical mapping.