Asymptomatic giant right atrial aneurysm.

A 5-year-old asymptomatic boy was found incidentally, on a chest radiograph, to have gross cardiomegaly; further evaluation by echocardiography showed a giant right atrial aneurysm. The patient underwent successful surgical reduction of the right atrium, closure of an atrial septal defect, and tricuspid valve repair These measures were taken to prevent thrombus formation in the right atrium, prevent paradoxical embolism, and lower the risk of atrial arrhythmias. The morphologic features of the resected atrial tissue showed paper-thin wall with a central aneurysm and focal endocardial fibrosis consistent with a diagnosis of idiopathic dilatation of the right atrium.