ABSTRACT
INTRODUCTION The morphology of the atria and the interatrial septum is complex.1,2 Echocardiography is the front-line approach to determining the integrity of the atrial septum. The combined use of high-resolution 2-D imaging, color Doppler and pervenous contrast echocardiography using either the precordial or transesophageal approach will usually define whether the atrial septum is intact or not, and if not, will characterize the morphology(s) of any defects. If doubt exists about the precise nature of a defect or if the morphology of pulmonary or systemic venous drainage needs to be clarified then a cardiac magnetic resonance imaging study should be undertaken. Angiography is usually superfluous but may be of value in detecting arterio-venous fistulae which may allow the early appearance of pervenous contrast in the left atrium and thus give the false impression of a right to left atrial shunt in patients with an intact atrial septum.
