Transesophageal echocardiography in the diagnosis of left atrial appendage aneurysm.
 Intrapericardial left atrial appendage aneurysm is rare.
 We describe the transthoracic and transesophageal echocardiographic findings in a 42-year-old man with atrial arrhythmia and an abnormal left atrial appendage on chest roentgenogram.
 Presence of an intrapericardial left atrial appendage aneurysm was confirmed at surgery.
