合田 亜希子, 正木 充, 増山 理

Akiko GODA, Mitsuru MASAKI, Tohru MASUYAMA

兵庫医科大学循環器内科

Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine

キーワード : mitral valve repair, mitral valve prolapse, functional mitral regurgitation, tethering, mitral clips

僧帽弁閉鎖不全症の手術件数は現在も増加傾向にある．リウマチ性の僧帽弁疾患は減少しているが，虚血性あるいは機能性の僧帽弁閉鎖不全症は心不全治療が進歩したこと，生活習慣病の増加などから今後も増加すると考えられる．また，弁形成術の技術が進歩し，その適応が広がっている．僧帽弁逸脱症の場合には逸脱部位や範囲，弁の肥厚・変性の有無により形成術の成功率が異なるため，心エコー図検査による詳細な評価が必要である．弁形成術は弁置換術と比較して術後の予後が良い．心房細動の慢性化や弁変性が進む前に形成術を施行した場合，その後の抗凝固療法も不要であることから，弁形成術が可能な段階での手術を考える必要がある．また，現在米国において経皮的僧帽弁クリッピング術が治験中である．適応に限定はあるものの，特に機能性僧帽弁閉鎖不全症例など心機能が著明に低下している症例において，より少ない侵襲による治療法に期待がもたれる．術後フォロー・アップに際しては弁機能，逆流の有無・程度，心機能を評価する．感染性心内膜炎や収縮性心膜炎の可能性についても念頭に置いておく必要がある．手術後はアーチファクトなどにより経胸壁心エコー図検査による評価が困難な場合がある．臨床的に弁機能不全や感染性心内膜炎が疑われる場合には積極的に経食道心エコー図検査を行う．人工弁の通過血流速は弁輪径，弁の種類によっても異なり，以前のデータとの比較が重要である．

The number of patients undergoing surgery for mitral regurgitation has been increasing. While the incidence of rheumatic mitral regurgitation has considerably decreased, ischemic or functional mitral regurgitation is a growing public health problem. This is at least partially because of an increase in life-style related diseases and advances in the management of patients with heart failure. Mitral valve repair is chosen when the valve is suitable for repair and appropriate surgical skill and expertise are available. Transthoracic or transesophageal echocardiography is important for the assessment of reparability by defining cause, mechanism, and location of lesions. Observational evidence suggests that the major surgical determinant of improved long-term outcome is valve repair. Chronic atrial fibrillation and mechanical valve replacement are associated with high risk of embolism and hemorrhagic complications (due to intensive anticoagulation). Increased mortality after replacement emphasizes the importance of early detection and assessment of mitral valve diseases. Experimental studies have shown successful and reliable mitral clip through trans-septal catheterization. A randomised trial comparing percutaneous mitral clip and surgery is in progress in the USA. While there might be important limitations, it is expected to be valuable in patients with impaired cardiac function due to ischemic or functional mitral regurgitation. Valvular function, incidence of leak (paravalvular and transvalvular), grade of regurgitation, and cardiac function are evaluated routinely at postoperative follow-up. The possibility of endocarditis and constrictive pericarditis should be considered. Transthoracic echocardiography is often limited when assessing a prosthetic valve because of the effect of acoustic shadowing. Transesophageal echocardiography provides excellent visualization especially in patients with mechanical valve replacement. The degree of obstruction varies with the type and size of the valve. Indices of echocardiography should be compared to the baseline or previous data.