Intrapericardial aneurysm of the left atrial appendix.

Aneurysms of the left atrium or its appendage are uncommon. Some occur with an intact pericardium and others are associated with a pericardial defect. The majority of patients are asymptomatic, but dysrhythmias and systemic embolism may occur. The condition should be suspected after chest radiography but can only be confirmed by angiocardiography. Resection is advised with cardiopulmonary bypass standing by. A patient with an intrapericardial aneurysm of the appendage correctly diagnosed by angiocardiography and successfully treated by simple excision is described.