田邊 一明

Kazuaki TANABE

島根大学医学部内科学講座第四

Fourth Department of Internal Medicine, Shimane University Faculty of Medicine

キーワード : prosthetic valve, echocardiography, Doppler, valvular heart disease

人工弁の評価は自己弁の評価と幾つかの重要な違いがある．1）人工弁には異なる種類，デザインの関係で血流動態の異なるものがある．また，正常人工弁でもサイズによって血流速度が異なる．2）人工弁の機能不全には自己弁の異常と機序が異なるものがある．3）人工弁そのものによる音響陰影，多重エコーなどのアーチファクトにより診断アプローチに影響が出ることがある．心エコーによる人工弁機能評価においては，基本的なアプローチ法を理解するだけでなく，どのような手術がなされたか，人工弁の種類・サイズによる血流動態の違いを理解して検査に臨む必要がある．

Echocardiographic evaluation of prosthetic valves is similar in many respects to evaluation of native valve disease. However, there are some important differences. First, there are several types of prosthetic valves with differing fluid dynamics for each basic design and differing flow velocities for each valve size. Second, the mechanisms of valve dysfunction are somewhat different from those for native valve disease. Third, the technical aspects of imaging artificial devices, specifically the problem of acoustic shadowing, significantly affect the diagnostic approach when prosthetic valve dysfunction is suspected. Both an understanding of the basic approach to echocardiographic evaluation and detailed knowledge of the specific flow dynamic for the size and type of prosthesis in an individual patient are needed for appropriate patient management.