[A large aneurysm of the interatrial septum simulating an atrial mass. Its identification by transesophageal echocardiography].

A patient with a large atrial septal aneurysm mimicking a right atrial mass is reported. Diagnosis was correctly obtained by transesophageal echocardiography. Clinical importance of this entity and usefulness of transesophageal echocardiography in its diagnosis is discussed.