Diagnosis of lipomatous hypertrophy of the atrial septum by two-dimensional echocardiography.

Originally described in 1964, lipomatous hypertrophy of the atrial septum currently remains a diagnosis established primarily at autopsy. Clinical interest in this disorder has centered on the reported association with supraventricular arrhythmias and sudden death. Because two-dimensional echocardiography allows detailed assessment of atrial septal configuration, we reviewed two-dimensional echocardiographic reports obtained over a 1 year period and identified 17 patients who had features consistent with lipomatous hypertrophy of the atrial septum. Nine were men and the average age was 70 years. Autopsy confirmation of the echographic findings was possible in one patient. In nine patients, ideal body weight was exceeded by 10% or more. The atrial septum viewed from the subcostal transducer position showed a distinctive echo-dense globular thickening sparing the valve of the fossa ovalis. The resultant tomographic image of the atrial septum had a characteristic dumbbell appearance. The mean thickness of the atrial septum was 21 mm (range 15 to 29). Seven patients had supraventricular arrhythmias, and eight had P wave abnormalities. The two-dimensional echocardiographic features described are distinctive and suggest that this technique is the procedure of choice not only for establishing the diagnosis of lipomatous hypertrophy of the atrial septum but also for providing a means for prospective follow-up of patients with this little known entity.