三尖弁閉鎖不全症を伴う特発性孤立性三尖弁逸脱症の一例

A case of idiopathic isolated tricuspid valve prolapse associated with tricuspid regurgitation

　特発性三尖弁逸脱症は極めて稀な疾患で，これまで本邦で2例，世界で13例の報告をみるのみである。我々は今回，超音波心断層図にて明らかなリウマチ性病変や細菌性心内膜炎の所見を欠き，三尖弁前尖の著明な逸脱と三尖弁逆流を伴う特発性三尖弁逸脱症と考えられる一例を経験したので，その診断，成因，治療について，文献的考察を加えて以下に報告する。

　A case of isolated tricuspid valve prolapse (TVP) associated with tricuspid regurgitation (TR) was reported here. The patient was a 19-year old male with pansystolic murmur at the 5th intercostal space along the left sternal border. The murmur was augmented following inhalation of amyl nitrate and intravenous injection of methoxamine. No abnormal finding in ECG and chest radiogram was found. Two-dimensional echocardiography showed that the tip of anterior tricuspid valve leaflet markedly prolapsed into right atrial cavity in early systole but no abnormality in mitral valve leaflets. On the other hand, any change of rheumatic or bacterial endocarditis in tricuspid valve leaflets was not demonstrated by the echocardiography. Therefore, we diagnosed him as idiopathic isolated TVP which might be caused by partial rupture of the chorda. Mild TR was detected by right ventriculography and contrast echocardiography. This is a rare case with idiopathic isolated TVP due to rupture of the chorda associated with TR.