ABSTRACT
INTRODUCTION For those wanting to perform device closure of the atrial septum, it is crucial to have a good understanding of the anatomy of this region of the heart. Each patient and each defect will have unique characteristics. Defects that allow interatrial shunting are sometimes found outside the confines of the atrial septum. Being able to interpret morphology in unusual cases, therefore, requires not only an understanding of normal anatomy but also an appreciation of the position of defects relative to surrounding cardiac structures. Description of anatomy can also become complicated if the heart is only considered in isolation and not in its attitudinally correct position. As I will illustrate, most of such problems can now be overcome by understanding the component parts that form the normal atrial septum while also appreciating the position of those structures relative to the body.
