Lipomatous hypertrophy of the interatrial septum: in vivo diagnosis.

Lipomatous hypertrophy of the interatrial septum (LHIS), a finding associated with obesity and advancing age, consists of the accumulation of adipose tissue, including fetal adipose tissue, in the interatrial septum cephalad and caudad to the fossa ovalis. Previous descriptions of this entity have been limited to autopsy examination. We report a patient in whom the diagnosis of LHIS was established during life by the use of computed tomographic cardiac imaging. As is often the case in patients discovered at autopsy to have LHIS, this patient had atrial fibrillation and, while in normal sinus rhythm, an abnormal P-wave morphology. This patient represents the first patient in whom the diagnosis of LHIS has been established during life. LHIS should be considered in the differential diagnosis of atrial fibrillation and other supraventricular rhythm/conduction disturbances, particularly in obese, elderly patients.