Mitral valve is a complex cardiac structure composed of several components to work in synchrony to allow blood flow into left ventricle during diastole and not to allow blood flow into left atrium during systole. Accessory mitral valve tissue (AMVT) was defined as existence of any additional part and parcel of valvular structure which has an attachment to normal mitral valve apparatus in left-sided cardiac chambers. AMVT may present itself in different clinical circumstances ranging from a silent clinical course to thromboembolic events, heart failure, left ventricular outflow tract obstruction, and severe arrhythmia. This article reviews the clinical perspectives of AMVT in terms of symptoms, diagnosis, and treatment, providing a new anatomical classification regarding the location of AMVT. Briefly type I refers to AMVT having attachments on the supra leaflets level, type II refers to attachments on the mitral leaflets, and type III refers to attachment below the mitral leaflets. Increased awareness and widespread use of echocardiographic techniques would increase recognition of AMVT in patients with heart murmurs but otherwise healthy and in those with left ventricular outflow tract obstruction or tissue which causes subaortic stenosis and with unexplained cerebrovascular events.

二尖瓣是一个复杂的心脏结构，由多个组件组成，这些组件可以同步工作，以允许心脏舒张期血液流入左心室，而在心脏收缩期血液不允许流入左心房。附件二尖瓣组织（AMVT）定义为瓣膜结构的任何其他部分和包裹，这些附件和组件与左侧心房中的正常二尖瓣装置相连接。AMVT可能会出现在不同的临床情况中，从无声的临床过程到血栓栓塞事件，心力衰竭，左心室流出道梗阻和严重心律失常。本文从症状，诊断和治疗的角度回顾了AMVT的临床观点，为AMVT的位置提供了新的解剖学分类。简而言之，I型是指在超小叶水平上具有附件的AMVT，II型是指在二尖瓣的小叶上的附件，III型是指在二尖瓣的小叶下的附件。超声心动图技术的提高认识和广泛使用将提高心脏杂音但其他方面健康的患者以及左心室流出道梗阻或引起主动脉瓣狭窄的组织以及原因不明的脑血管事件的患者对AMVT的认识。