心エコー所見が特徴的であったEdwards-TEKNA bileaflet valve弁葉脱落の1例

A Case of Leafiet Escape in an Edwards TEKNA Bileatlet Valve Characterized by Echocardiography

　41歳，男性．1995年3月に僧帽弁置換術（Edwards TEKNA弁）および大動脈弁置換術（Medtronic Hall弁）を受けた．14カ月後に突然呼吸困難が出現，肺水腫状態で救急搬入された．心エコー検査で音響陰影を伴い左室内を高速で浮遊する異物を認め，TEKNA弁の弁葉脱落と診断した．患者は翌朝再手術を受け軽快退院した．術中所見では脱落したTEKNA弁弁葉の半分は左室内で発見されたが残りは流失していた．人工弁弁葉脱落は極めて稀だが死に至る重篤な合併症である．迅速な確定診断は困難で，心エコーでも血栓化機械弁と誤認されることが多い．本例は2弁置換後で，弁葉片の一部が大動脈弁を越えられず，早期診断が可能であった．二葉弁は一葉が機能不全に陥っても，残る弁葉が正常ならば死に至るまでにわずかな猶予があるが，この貴重な時間に確定診断を得て再手術に踏み切ることが救命のポイントと考えられた．

The following is a case of a 41-year-old man with leaflet escape in the Edwards-TEKNA valve at 14 months after implantation. He underwent mitral valve replacement (Edwards-TEKNA prosthesis. 27mm) and aortic valve replacement (Medtronic Hall prosthesis, 20mm) in March 1995.

In May 1997, the patient experienced sudden severe dyspnea and pulmonary edema and was admitted to our hospital. In the acute phase the echocardiogram revealed a foreign body with an acoustic shadow which was moving about rapidly in the left ventricle. He was immediately diagnosed as having leaflet escape in the Edwards-TEKNA valve. The patient was operated on the next day and he recovered well. During open heart surgery, it was noted that one of the bileaflet valves had escaped from its' housing. Half of this broken leaflet had been released, while the other half remained in the left ventricle.

Though leaflet escape after prosthetic valve replace-ment is a rare complication, the outcome can be lethal. Exact diagnosis for leaflet escape cannot be obtained by physical examination or fluoroscopy. Even echocardio-gram rarely distinguishes leaflet escape from prosthetic valve thrombosis. Immediate and accurate diagnosis was obtained in this case because half of the escaped-. leaflet could not slip through the Medtronic Hall aortic prosthesis. In prosthetic valve related complications, such as leaflet escape, bileaflet prosthesis has an obvious advantage in that the other unaffected leaflet can main-tain the patient's vital signs for a few hours. Thus, to treat prosthetic valve related complications, it is essen-tial to obtain a precise diagnosis and operate without delay.