Chest
Volume 124, Issue 6, December 2003, Pages 2068-2073
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Clinical Investigations
CARDIOLOGY
Lipomatous Hypertrophy of the Interatrial Septum: A Prospective Study of Incidence, Imaging Findings, and Clinical Symptoms

https://doi.org/10.1378/chest.124.6.2068Get rights and content

Background

Lipomatous hypertrophy of the interatrial septum (LHIS) is a benign disorder characterized by fat accumulation in the interatrial septum. It typically occurs in elderly, obese patients and may cause arrhythmia.

Objectives

The purpose of this study was to determine the imaging features of this cardiac pathology using multislice CT (MSCT), and its relationship with clinical findings.

Materials and methods

A total of 1,292 consecutive patients who underwent MSCT of the thorax from September 2001 to August 2002 were prospectively studied. Beside the analysis of patient records, the amount of fat in the interatrial septum, and its size and shape were determined.

Results

Among the 1,292 patients investigated, we found 28 (2.2%) with LHIS. The mean age of affected patients was 72.2 years. MSCT studies revealed a mass of fat attenuation with sharp margins and sparing of the fossa ovalis, resulting in a dumbbell shape in all patients. The median thickness of the interatrial septum was 32 mm (range, 20 to 62 mm), and the median craniocaudal extend was 62 mm (range, 51 to 89 mm). Twenty-one patients (75.0%) showed increased epicardial fat, 18 patients (64.3%) had significant pulmonary emphysema, and 13 of 21 patients (61.9%) showed ECG abnormalities. Three patients underwent functional cardiac MRI studies. In one patient, hemodynamic obstruction by LHIS was shown.

Conclusions

MSCT scanning is a useful method to diagnose LHIS, a cardiac condition that in our series reached a 2.2% incidence. The lesion shows characteristic features, thus differentiating it from other cardiac tumors. Advanced age, obesity, pulmonary emphysema, and atrial arrhythmias are common additional findings in patients with LHIS.

Section snippets

Materials and Methods

From August 2001 to September 2002, a total of 1,292 patients underwent a contrast-enhanced thoracic CT scan at our institution. All examinations were done on a multislice-CT (MSCT) scanner (SOMATOM Volume Zoom; Siemens; Erlangen, Germany) using a breathhold technique, and identical technical parameters (ie, caudocranial data acquisition, collimation of 4 × 1.0 mm or 4 × 2.5 mm, and slice thickness of 3 or 6 mm). Eighty milliliters contrast agent (Solutrast 300; Byk Gulden; Konstanz, Germany)

Results

In the 1,292 patients investigated, we found 28 (2.2%; 16 women and 12 men) with LHIS. Clinical findings in our patient population are shown in Table 1.

The mean age of affected patients was 70.2 years (range, 57 to 87 years). Twelve of 28 patients (42.9%) showed a BMI of > 30. In 13 of 21 patients (61.9%), ECG rhythm abnormalities were present, and 8 patients showed atrial arrhythmias (atrial fibrillation, 5 patients; atrial premature complexes, 2 patients; and atrial tachycardia, 1 patient).

CT

Discussion

LHIS, also called “massive fatty deposits”14 or “lipomatous hamartoma,”15 is a well-known but uncommon finding with the accumulation of adipose tissue in the interatrial septum. After the first postmortem description in 1964,16 about 200 cases have been reported. Histologic studies in affected patients typically show hyperplasia of mature multivacuolated fat cells. Fetal fat, hypertrophied myocytes, myocardial fibers, and fibrosis in various quantities may be found.214 Although many theories

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