Types and mechanisms of mitral valve regurgitation

Abstract

Carpentier’s classification helps us understand the underlying mechanisms of mitral regurgitation (MR). MR due to leaflet deformation is called degenerative MR (DMR, or primary MR), most of which is mitral valve prolapse. It is divided into fibroelastic deficiency (FED), in which chordal rupture is the main factor, and Barlow disease, in which enlargement of the valve leaflet is the main factor. In many patients with MV prolapse, both mechanisms coexist. Because mitral valvuloplasty has been established as a reliable treatment for MV prolapse, evaluation by preoperative 3D transesophageal echocardiography is becoming increasingly important. MR without deformation in the valve leaflet itself is classified as functional MR (FMR, or secondary MR). This is caused by the valve leaflet being tethered towards the apex due to left ventricular (LV) dilation or LV dysfunction. The severity assessment by the proximal isovelocity surface area (PISA) method in FMR patients tends to be underestimated. The effect of annuloplasty alone is insufficient, and treatment with MitraClip may be effective. Atrial MR is usually defined as significant MR appearing in patients with normal LV volume and contractile function, and an enlarged left atrium. Conventionally, valve annuloplasty or valve replacement has been performed for symptomatic atrial MR. Recently, however, valve repair with posterior mitral leaflet (PML) augmentation using pericardial patch or treatment with MitraClip has been attempted. The heart team members need to understand these mechanisms of MR when making treatment plans.