[Transesophageal echocardiography].

Atrial septal aneurysm (ASA) is a rare, localized deformity of the atrial septum that is usually identified as an incidental finding by twodimensional echocardiography .' Because the lesion is located far from the transducer on the chest wall, it is apparent that transesophageal echocardiography (TEE) is superior to transthoracic echocardiography (TTE) in visualizing the morphology of ASA.' However, misdiagnosis may at times occur because of the polymorphous presentation of ASA.3 In this report, we present two patients with large ASAs appearing as right atrial masses by TEE. atrial septum. The mass exhibited phasic motion and variable morphology with the oscillation of cardiac motion (Figure 1). As the transducer was rotated upward, the aneurysm of the atrial septum was demonstrated (Figure 2). The atrial septum appeared free of any defect. To obtain a histological diagnosis for this mass and correct the potential source of embolization, the patient underwent open-heart surgery. A large aneurysm involving the fossa ovalis was noted to be protruding into the right atrium; no mass, thrombus, or defect was detected within the aneurysm. The aneurysm was resected, and the patient subsequently had an uneventful recovery.