Mechanisms of atrial flutter: implications for ablative therapy.

Much has been learned about atrial flutter mechanisms from studies in animal models and in patients. In fact, it seems virtually always due to some form of reentry. Furthermore, it seems likely that there is more than one location of the atrial flutter reentrant circuit in patients, although the reentrant circuit in most instances of atrial flutter seems to be activation up the interatrial septum and then down the posterior right atrial free-wall. Other locations of the reentrant circuit may include the right atrial free-wall alone or the tricuspid valve annulus, among others. Resolution of this awaits better mapping data from human studies. Clearly, an understanding of mechanism is central to achieving effective ablation. Thus, if it is possible to identify a critical aspect or aspects of the atrial flutter mechanism vulnerable to therapy with ablative energy, effective treatment using ablative techniques should be successful.