Congenital giant aneurysm of the left atrial appendage mimicking pericardial absence - Case report

A 25-year-old man was found to have an abnormal cardiac contour on a chest radiograph, and was referred. Transesophageal echocardiography suggested he rniation of the left atrial appendage (LAA) through a gap in the pericardiu m, and magnetic resonance imaging indicated congenital partial absence of t he pericardium. Cardiac dysfunction was caused by compression from the enla rged left atrium and thrombi were thought to be present in the appendage, s o surgery was performed. The intraoperative diagnosis was congenital LtZA a neurysm. Although distinguishing between congenital LAA aneurysm and congen ital absence of the pericardium is reported to be possible with magnetic re sonance imaging, we were unable to so in this case.