超声心动图
在二维影像学的胸骨旁长轴位或心尖位，瓣叶脱垂超过瓣环2mm及以上。[5]Levine RA, Triulzi MO, Harrigan P, et al. The relationship of mitral annular shape to the diagnosis of mitral valve prolapse. Circulation. 1987 Apr;75(4):756-67.http://www.ncbi.nlm.nih.gov/pubmed/3829339?tool=bestpractice.com[6]Levine RA, Stathogiannis E, Newell JB, et al. Reconsideration of echocardiographic standards for mitral valve prolapse: lack of association between leaflet displacement isolated to the apical four chamber view and independent echocardiographic evidence of abnormality. J Am Coll Cardiol. 1988 May;11(5):1010-9.https://www.sciencedirect.com/science/article/pii/S0735109798900596?via%3Dihubhttp://www.ncbi.nlm.nih.gov/pubmed/3281989?tool=bestpractice.com
[Figure caption and citation for the preceding image starts]: 胸骨旁长轴位上二尖瓣的超声心动图像描述了瓣叶后叶脱垂（红色箭头）来自 Brian Griffin, MD 的个人资料；经许可后使用 [Citation ends].
