A 60-year-old woman with a history of chronic obstructive pulmonary disease and diabetes mellitus presented with a 5-day history of severe shortness of breath and productive cough. Her blood pressure was 86/54 mmHg; her oxygen saturation, 70%; and her heart rate, 110 beats/min. Physical examination revealed an irregularly irregular heart rate and bilateral expiratory wheezing. The patient needed urgent intubation in the intensive care unit because of acute hypoxic respiratory failure. A computed tomographic angiogram of the chest incidentally showed a 5 × 3.5-cm lipomatous mass in the upper two thirds of the interatrial septum (Fig. 1), with clear sparing of the fossa ovalis. Transthoracic and transesophageal echocardiograms (Figs. 2 and 3) and added color-flow Doppler mode (Fig. 4) confirmed lipomatous hypertrophy of the interatrial septum (LHIS)—about 5 cm at its greatest dimension—and restriction of right atrial filling with obstruction of the superior vena cava.
Most such lesions do not require invasive intervention. However, we thought that our patient's arrhythmias, filling restriction, and hemodynamic instability were secondary to the cardiac mass, and that surgical resection was the best option.1 Her hemodynamic status improved substantially after resection of the lesion.
Lipomatous hypertrophy of the interatrial septum is not a true tumor. It has been defined as a >2-cm-thick epicardial fatty deposition in the atrial septum.2 The defining features of LHIS are as follows: the specific septal location of the atrial thickening (which tends to be greater than 2 cm and typically spares the fossa ovalis), and a classic dumbbell or hourglass shape. In our patient, the dumbbell shape was evident, but very unbalanced because of the extensive LHIS. Also typical of LHIS, the tissue is isodense to the surrounding subcutaneous fatty tissue and is nonencapsulated, unlike the encapsulated nature of its related formation, the lipoma. Because the structural features of LHIS are so distinct from those of any other intracardiac mass, it is widely accepted that the diagnosis can be made confidently by means of noninvasive imaging and without tissue biopsy.3
Section Editor: Raymond F. Stainback, MD, Department of Adult Cardiology, Texas Heart Institute, 6624 Fannin St., Suite 2480, Houston, TX 77030
From: Department of Internal Medicine (Drs. Edla, Elsherbiny, and Ravakhah), St. Vincent Charity Medical Center, Cleveland, Ohio 44115; and Department of Cardiovascular Medicine (Dr. Hoit), University Hospitals, Cleveland, Ohio 44106