異種生体弁の心音図・心機図と心エコー図所見

Phonocardiographic and echocardiographic features of the porcine bioprosthesis

　近年，血栓形成が少なく，中心流を障害しない異種生体弁が，従来の人工弁に代って数多く使用されるようになってきている^4〜9）。一方，若干問題のあった異種生体弁の耐久性に関しては処理方法の改善^5,6）などにより向上がみられるようになってきているので，今後はますます本弁が頻用されるものと予想される。したがって本弁の機能評価の重要性もまた増加しつつある。最近，心カテーテル検査から本弁の機能評価を試みた報告が発表されるようになってきた^1〜4,7,8）。しかしながら弁置換術後の弁機能の検討は再々にわたり行われる必要があるため，非観血的検査法を用いた本弁の機能評価の確立が望まれるところである。今回，著者らは非観血的検査法である心音図と心エコー図を用いて本弁移植例の検討を行ったので，その結果を報告する。

Fifteen cases with porcine bioprosthesis (8 cases mitral, 5 aortic, 1 pulmonic, and 1 both mitral and tricuspid) were studied by non-invasivemethods including phonocardiography, external pulse tracings and echocardiography, and cardiac cathterization. Of the 9 cases with a mitral porcine valve, mid-diastolic murmur was observed in all and pre-systolic murmur in 2 of 3 cases with sinus rhythm. Cardiac catheterization re-vealed a mild pressure gradient across the mitral valve in all. The echocardiographic features of the porcine mitral valve included the stent echoes represented by two parallel echoes in the left ventricle and the cusp echoes represented by a box-like configuration in diastole similar to the normal aortic valve. Of the 5 cases with a aortic porcine valve, 4 had long ejection systolic murmur and the carotid pulse contour typical of aortic stenosis, suggesting the presence of aortic stenosis. The echocardiographic appearance of the stent consisted of two lines parallel to each other within the aortic root. The valve cusps had a box-like appearance in systole and a single echoe in dia-stole, similar to that of the normal aortic valve. In the case with a tricuspid porcine valve, an extra diastolic sound and mid-diastolic murmur were observed. The echocardiographic findings were similar to those of the mitral porcine valve. Again, the echocardiographic features of the pulmonic porcine valve were similar to those of the aortic porcine valve. In summary, noninva-sive methods including phonocardiography, ex-ternal pulse tracings and echocardiography may prove to be useful in the assessment of the func-tion of the porcine valves.