Idiopathic Enlargement of the Right Atrium

Four patients with idiopathic enlargement of the right atrium are described. All patients were evaluated carefully by clinical means and two were subjected to extensive investigation including cardiac catheterization, angiocardiography, and intracavitary electrocardiography.The diagnosis of idiopathic enlargement of the right atrium is based primarily on radiographic examination with exclusion of other causes of right atrial enlargement by appropriate clinical and laboratory means. In the patients studied no cause for the right atrial abnormality could be established. Nonetheless, it is concluded that this disease is a distinct clinical entity that deserves further recognition and investigation.