The aim of this study was to report unusual echocardiographic findings in patients on long-term home parenteral nutrition suggesting lipomatous hypertrophy of the cardiac interatrial septum. Seven patients (two women and five men, mean age 58 years) were prospectively evaluated by two-dimensional echocardiography before and during home parenteral nutrition for severe short-bowel syndrome. Parenteral caloric intake was 33 +/- 4 kcal/kg per day (mean +/- SD), with a mean supply of lipid emulsion of 1 g/kg per day. The first echocardiography, performed before initiation of home parenteral nutrition, was normal in the seven patients. The second echocardiography, performed 5 to 43 months (mean 20 months) later, revealed a significant increase of the thickness of the atrial septum in all patients (+8.3 +/- 3.6 mm; p < 0.01), consistent with the diagnosis of lipomatous hypertrophy in four patients, and moderate fat accumulation in two others. The septum thickness measured after the nutritional support period was significantly correlated (p < 0.05) with the total amount of nutrient and lipid infused. Cardiac nuclear magnetic resonance imaging was performed in two patients; it suggested the adipose nature of interatrial septum deposit. None of the patients developed clinical or electrocardiographic symptoms during the period of nutrition. We suggest that patients undergoing long-term home parenteral nutrition be screened for this new and unusual cardiac abnormality. Whether the latter might have clinical consequences in these patients remains to be determined.