Normal and Abnormal Atrial Anatomy Relevant to Atrial Flutters: Areas of Physiological and Acquired Conduction Blocks and Delays Predisposing to Re-entry.

This article reviews the structure of the atrial chambers to consider the anatomic bases for obstacles and barriers in atrial flutter. In particular, the complex myocardial arrangement and composition of the cavotricuspid isthmus could account for a slow zone of conduction. Prominent muscle bundles within the atria and interatrial, and myoarchitecture of the walls, could contribute to preferential conduction pathways. Alterations from tissue damage as part of aging, or from surgical interventions could lead to re-entry.