在发达国家，二尖瓣脱垂是慢性二尖瓣反流的最常见病因。
收缩期二尖瓣1或2个瓣叶脱垂进入左心房。
依据过临床检查及超声心动图建立诊断。
通常伴随具有良好预后的良性进展过程。
偶有严重并发症出现，例如感染性心内膜炎、二尖瓣重度反流及心脏性猝死的。具有某些临床及超声心动图特征的患者有较高风险。
对于有二尖瓣脱垂及二尖瓣重度反流的患者，二尖瓣修复术是优选的治疗方案。
二尖瓣脱垂被定义为收缩期瓣叶脱垂，二尖瓣的1或2个瓣叶可脱垂进入左心房。[1]Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2021 Feb 2;143(5):e72-e227.
https://www.doi.org/10.1161/CIR.0000000000000923
http://www.ncbi.nlm.nih.gov/pubmed/33332150?tool=bestpractice.com
[2]Bonow RO, O'Gara PT, Adams DH, et al. 2020 Focused update of the 2017 ACC expert consensus decision pathway on the management of mitral regurgitation: a report of the American College of Cardiology Solution Set Oversight Committee. J Am Coll Cardiol. 2020 May 5;75(17):2236-70.
https://www.doi.org/10.1016/j.jacc.2020.02.005
http://www.ncbi.nlm.nih.gov/pubmed/32068084?tool=bestpractice.com
[3]Zoghbi WA, Adams D, Bonow RO, et al. Recommendations for noninvasive evaluation of native valvular regurgitation: a report from the American Society of Echocardiography developed in collaboration with the Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr. 2017 Apr;30(4):303-71.
https://www.doi.org/10.1016/j.echo.2017.01.007
http://www.ncbi.nlm.nih.gov/pubmed/28314623?tool=bestpractice.com
[4]Freed LA, Benjamin EJ, Levy D, et al. Mitral valve prolapse in the general population: the benign nature of echocardiographic features in the Framingham heart study. J Am Coll Cardiol. 2002 Oct 2;40(7):1298-304.
https://www.sciencedirect.com/science/article/pii/S0735109702021617?via%3Dihub
http://www.ncbi.nlm.nih.gov/pubmed/12383578?tool=bestpractice.com
在患有 MVP 时，瓣叶在舒张期增厚 5 mm 或更多反映了黏液瘤样变性，这被认为是典型的脱垂，是并发症的一个预测指标。[5]Marks AR, Choong CY, Sanfilippo AJ, et al. Identification of high-risk and low-risk subgroups of patients with mitral-valve prolapse. N Engl J Med. 1989 Apr 20;320(16):1031-6.
http://www.ncbi.nlm.nih.gov/pubmed/2927482?tool=bestpractice.com
[6]Nishimura RA, McGoon MD, Shub C, et al. Echocardiographically documented mitral valve prolapse: long-term follow-up of 237 patients. N Engl J Med. 1985 Nov 21;313(21):1305-9.
http://www.ncbi.nlm.nih.gov/pubmed/4058522?tool=bestpractice.com
相关的二尖瓣反流程度由无到重度。
二尖瓣瓣叶及瓣环是马鞍形的。[7]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
[8]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%3Dihub
http://www.ncbi.nlm.nih.gov/pubmed/3281989?tool=bestpractice.com
MVP 的超声心动图定义如下：胸骨旁长轴切面显示心脏收缩期瓣叶脱垂超出瓣环水平 ≥2 mm。[3]Zoghbi WA, Adams D, Bonow RO, et al. Recommendations for noninvasive evaluation of native valvular regurgitation: a report from the American Society of Echocardiography developed in collaboration with the Society for Cardiovascular Magnetic Resonance. J Am Soc Echocardiogr. 2017 Apr;30(4):303-71.
https://www.doi.org/10.1016/j.echo.2017.01.007
http://www.ncbi.nlm.nih.gov/pubmed/28314623?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].
在诸如心尖四腔切面等其他超声心动图切面上，即使二尖瓣瓣叶在整个瓣膜水平以下，其仍可能表现为脱垂。 在既往的研究中，这种现象常导致二尖瓣脱垂的误诊。[9]Warth DC, King ME, Cohen JM, et al. Prevalence of mitral valve prolapse in normal children. J Am Coll Cardiol. 1985 May;5(5):1173-7.
https://www.sciencedirect.com/science/article/pii/S0735109785800218?via%3Dihub
http://www.ncbi.nlm.nih.gov/pubmed/3989128?tool=bestpractice.com
[10]Savage DD, Garrison RJ, Devereux RB, et al. Mitral valve prolapse in the general population. 1. Epidemiologic features: the Framingham study. Am Heart J. 1983 Sep;106(3):571-6.
http://www.ncbi.nlm.nih.gov/pubmed/6881031?tool=bestpractice.com
