Conduction barriers of atrial flutter: relation to the anatomy

Atrial flutter (AFL) is a common arrhythmia in clinical practice. Several experimental models such as tricuspid ring model, tricuspid regurgitation model, and atrial crush injury model have provided important information about the role of conduction barriers in the reentrant circuit. Human typical AFL uses the tricuspid annulus as the anterior barrier, and uses the crista terminalis, Eustachian ridge, and sometimes sinus venosa as the posterior boundary. Rate-dependent conduction block was found in the crista terminalis and sinus venosa. Some barriers such as the crista terminalis and Eustachian ridge are not intact. The conduction gap in the barrier can produce another kind of arrhythmia. Understanding the barriers of AFL is necessary for successful radiofrequency ablation.