Partial left pericardial defect with herniation of the left atrial appendage.

A case is reported of herniation of the left atrial appendage through a partial pericardial defect, probably congenital. The diagnosis was suggested by the history of chest pain and bulging of the middle segment of the left heart border on the plain chest film, without other signs. Angiography revealed a dilated left atrial appendage. An artificial left pneumothorax confirmed the presence of a pleuropericardial defect. The surgical procedure included excision of the appendage and closure of the defect.