[Slow increase in the size of the left atrium with atrial fibrillation--a congenital pericardial defect or aneurysm of the left atrium?].

Gradual left atrial enlargement and development of atrial fibrillation--congenital pericardial defect or left atrial aneurysm? Left atrial aneurysms are rare. Whether or not a pericardial defect is associated can be ascertained by a diagnostic left-sided pneumothorax with air entering the pericardial cavity, although a negative finding does not necessarily rule out the presence of a defect. Cardiac surgery (aneurysmectomy) is advisable if the patient develops significant symptoms or if there is a progressive increase in atrial size. A case is presented with progressively increasing left atrial aneurysm and the development of atrial fibrillation. Although a pericardial defect was postulated (from echocardiogram, MR, CT, angiogram) the pericardium was found to be intact at surgery.