Lipomatous hypertrophy of the atrial septum: diagnosis with fat suppressed MR imaging

71-year-old woman with dizziness and lipomatous hypertrophy of the left atrium

Lipomatous hypertrophy, an unencapsulated atrial mass of adipose tissue, occurs in 1% of the population; the clinical significance of this is uncertain. Diagnosis is by echocardiography, computed tomography or magnetic resonance imaging scan. Surgical intervention is thought to be indicated in patients with obstruction, thromboembolism, uncontrollable arrhythmia or when liposarcoma cannot be excluded. We describe a case in which a 71-year-old woman was diagnosed with lipomatous hypertrophy of the left atrium. The finding of a large atrial mass was unexpected in this case. The clinical implications of the finding are unclear, since the aetiology and prognostic consequences are unknown. As the finding is not that uncommon others may find similar cases. It is therefore important that echocardiographers are aware of this entity and the aspects one needs to consider when deciding upon the best evaluation and treatment strategy.

Lipomatous hypertrophy of the interatrial septum: a pathological and clinical approach

Lipomatous hypertrophy of the interatrial septum (LHIS) is a rare benign disorder that is characterized by accumulation and deposition of fat in the interatrial septum. Its etiology is still unknown, despite the theories that have been suggested. It usually occurs in older, obese people with a higher incidence in women. In most cases, it remains asymptomatic, thus its diagnosis is rarely made during a person's lifetime and it is made incidentally or during autopsy. LHIS can cause atrial arrhythmias, obstructive flow symptoms and sometimes death. The diagnosis of LHIS can be made by the use of imaging techniques, with the best results given by multislice-CT (MSCT) scanning. Surgical intervention is usually avoided and the best management is early diagnosis, reassurance and inactivity. However, in cases of severe superior vena cava obstruction or intractable rhythm disturbance, surgical excision is performed together with reconstruction of the interatrial septum.

Technology insight: MRI of the myocardium

MRI is emerging as the method of choice for the evaluation of a wide variety of cardiovascular disorders. A major advantage of this technique over the other cardiac imaging modalities is the fact that it allows the operator--via special software programs called pulse sequences--to probe a vast array of biological properties while using the same machine. In this review, we provide the reader with a brief overview of the pulse sequence concept and how it enables MRI practitioners to pursue a multifaceted approach to evaluating the myocardium. We discuss how MRI technology makes this imaging method ideally suited to the assessment of cardiac morphology, contractile function, myocardial perfusion and infarction. In addition, we present clinical scenarios in which the performance of multifaceted imaging by MRI can alter clinical decision making.

Lipomatous hypertrophy of the interatrial septum: a prospective study of incidence, imaging findings, and clinical symptoms

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.

Can cardiac magnetic resonance imaging reliably differentiate between benign and neoplastic fat?

Magnetic resonance imaging is currently frequently used to differentiate lipomatous hypertrophy of the interatrial septum from other cardiac lesions involving abnormal fatty tissue including lipomatous neoplasms. This report discusses potential problems with this approach by emphasizing the variable appearance of lipomatous hypertrophy of the interatrial septum on magnetic resonance imaging.