尾辻 豊

Yutaka OTSUJI

産業医科大学第2内科学

Second Department of Internal Medicine, University of Occupational and Environmental Health

キーワード : mitral regurgitation, ischemic heart disease, chronic heart failure, echocardiography

虚血性僧帽弁逆流の基本機序は，左室拡大により外側へ変位した乳頭筋が弁尖を異常に強く牽引しその可動性を低下させ（テザリング），弁尖閉鎖不全を来たすことである．弁輪拡大や左室機能低下は，中心的な機序ではないが，テザリングがあると弁逆流悪化に寄与する．乳頭筋機能低下は，僧帽弁逆流の原因であると考えられた．しかし，乳頭筋機能低下では僧帽弁逆流が出現しないことが何度も確かめられ，最近の研究では乳頭筋機能低下は僧帽弁逆流を弱める因子であることが確認された．外科的弁輪形成術は虚血性僧帽弁逆流に有効であるが，しばしば逆流が再発する．弁下部テザリングを治療する手技が求められている．僧帽弁テザリングは症例により多様であり，個々の症例の病態に応じた治療が望まれる．

The basic mechanism of ischemic mitral regurgitation (MR) is augmented leaflet tethering due to the outward displacement of the papillary muscles by left ventricular (LV) remodeling or dilatation. Annular dilatation and LV dysfunction may not be the central mechanism, but they contribute to the development of MR in the presence of augmented tethering. Papillary muscle dysfunction was initially expected to cause leaflet prolapse and MR. However, multiple studies have confirmed that papillary muscle dysfunction per se does not usually cause ischemic MR, and recent studies further suggest that papillary muscle dysfunction may occasionally attenuates tethering and MR. Although surgical annuloplasty is usually effective for treating ischemic MR, occasional patients with persistent or recurrent ischemic MR after surgical ring annuloplasty even with advanced down sizing suggest the need for approaches to address tethering. Finally, leaflet tethering in patients with ischemic MR can be heterogeneous, indicating the need for individualized approaches to correct ischemic MR in affected patients.