兄弟に発症した特発性右房拡張症

Familial idiopathic enlargement of the right atrium

　誘因なく右房が拡張する特発性右房拡張症は極めてまれな疾患である。原因として一般的には先天性と考えられているがいまだ不明の点が多い^1,2）。今回我々は病因を考えるうえできわめて興味深い，兄弟に発生した特発性右房拡張症を経験したので報告する。

A 45 year-old-man was admitted because of dysp-nea and general edema. Echocardiography and car-diac catheterization showed a huge dilatation of the right atrium. Slight tricuspid regurgitation was ob-served by pulsed-Doppler echocardiography and con-trast echocardiography. He died because of right heart failure and emaciation. Autopsy showed that the right atrium was strikingly enlarged. The right atrial wall was paper thin and translucent with visible. Cardiac valves were intact. His eldest bro-ther died by the same disease at the age of 60 and his forth brother died suddenly at the age of 21. This case is considered as a first case of familial idopathic dilatation of the right atrium.