[Cerebral embolism due to lone atrial septal aneurysm].

A 71-year-old man was admitted to our hospital because of headache and left hemiparesis. Brain CT scan showed hemorrhagic infarction of the right frontal lobe. Intravenous digital subtraction angiography revealed no occlusion of cerebral arteries. No arrhythmias were observed by the holter ECG. Transthoracic echocardiography showed no abnormalities. Anticoagulation therapy (heparin and warfarin) was started under the diagnosis of cerebral embolism without definite embolic source and there was no recurrence during following four years. Transesophageal echocardiography showed an atrial septal aneurysm (ASA) without patent foramen ovale. A potential cause of cerebral embolism due to atrial septal aneurysm is paradoxical embolization through an interatrial shunt (patent foramen ovale). It was speculated that ASA was a direct source of thrombus formation in this case (lone ASA). Transesophageal echocardiography should be performed to find atrial septal aneurysm in patients with cryptogenic stroke, especially embolic stroke without definite embolic sources.