小糸 仁史, 大久保 直彦, 林 佳代, 中森 久人, 鈴木 淳一, 岩坂 壽二, 稲田 満夫

Hitoshi KOITO, Naohiko OHKUBO, Kayo HAYASHI, Hisato NAKAMORI, Junichi SUZUKI, Toshiji IWASAKA, Mitsuo INADA

関西医科大学第2内科・心臓血管病センター

The Second Department of Internal Medicine・Cardiovascular Center, Kansai Medical

キーワード : Lipomatous hypertrophy of the interatrial septum, Supraventricular arrhythmia, Transthoracic echocardiography, Transesophageal echocardiography, Magnetic resonance imaging

Lipomatous hypertrophy of the interatrial septum (LHIAS) is a rare cardiac abnormality, initially described by Prior in 1964, with clinical interest in its association with supraventricular arrhythmia. A 20-year-old-man consulted our hospital for examination of his arrhythmia without any symptoms. A twelve-lead electrocardiogram (ECG) showed an interatrial conduction defect and a Holter ECG showed high-grade sinus arrhythmia and frequent supraventricular premature beats. Transthoracic two-dimensional echocardiography revealed an echogenic mass-like structure at the interatrial septum (IAS). An echogenic dumbbell-shaped configuration of the IAS, with a thin echo at the level of the fossa ovalis, was revealed by transesophageal echocardiography. The T1-weighted magnetic resonance imaging using spin-echo technique demonstrated a dumbbell-shaped IAS with the same high signal intensity as subcutaneous fat. Computerized tomography showed low density of the IAS which was compatible with fat. LHIAS was diagnosed by these results. The results suggest that a precise examination of the IAS is needed for patients with supraventricular arrhythmia of unknown origin even in the young adult population.