経食道心エコー図にて観察しえた大動脈弁位血栓弁の1例

Diagnosis of Thrombosed Bjork-Shiley Aortic Prosthesis by Transesophageal Echocardiography:A case report

　今回われわれは，経食道心エコー図にて大動脈弁位の機械弁（Björk-Shiley弁，B-S弁）置換術後の血栓弁を明瞭に観察しえた症例を経験した．症例は48歳，男性で，労作時呼吸困難と胸痛を主訴に入院した．聴診で，収縮期駆出性雑音と拡張早期雑音を聴取した．経胸壁心エコー・ドプラ法では，左室—大動脈圧較差は155mmHgと著しい上昇を認め，人工弁狭窄が疑われた．しかし，断層図からは明らかな血栓の描出は困難であった．経食道アプローチによれば，B-S弁のminor orificeの大動脈側から左冠状動脈入口部付近にかけて付着した血栓の描出が可能であった．本例は，緊急手術を施行され，心エコー図での所見が確認された．TEEは大動脈弁位の血栓化B-S弁の描出に有用であった．

A 48-year old man underwent aortic valve replace-ment with a Björk-Shiley (B-S) prosthesis 8 years ago. He was admitted due to progressive dvspnea on exertion and chest pain. In auscultation, an ejection systolic murmur and an early diastolic murmur were noted. Transthoracic echocardiography (TTE) did not reveal the thrombus occluding the minor orifice of the B-S valve, although markedly increased flow velocity (6.2m/ s) through the B-S valve was measured by continuous-wave Doppler echocardiography. By multiplane trans-esophageal echocardiography (TEE). it was possible to detect the thrombosed B-S valve. At the time of opera-tion, thrombosed B-S valve was confirmed. In conclu-sion, TEE is useful in visualizing a thrombosed 13-S aortic valve.