Pathoanatomy of Mitral Regurgitation

The mitral valve is a dynamic, three-dimensional (3D) structure consisting of the mitral annulus, leaflets, tendinous chordae, and papillary muscles. Mitral regurgitation (MR) is defined as an abnormal reversal of blood flow from the left ventricle to the left atrium, occurring most commonly during ventricular systole. The etiologies of MR can be divided into primary abnormalities of the mitral valve apparatus and secondary causes that do not directly involve the mitral valve. Recognition of MR is clinically important, as it represents an increasingly prevalent valvular disease associated with significant morbidity and mortality. In this article, we will first review normal mitral valve anatomy, highlighting the individual structure and function of each component of the mitral valve apparatus. We will then discuss the approach to classification of mitral valve disease, including the classic Carpentier approach as well as recent proposed modifications to this classification schema. Next, we will highlight several novel mechanisms of MR that have recently been described in the literature. Finally, we will discuss the integral role of 3D echocardiography in the diagnosis and management of MR.