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| '''Mitral valve prolapse''' ('''MVP''') is a [[valvular heart disease]] characterized by the displacement of an abnormally thickened [[mitral valve]] leaflet into the left atrium during [[systole]]. In its nonclassic form, MVP carries a low risk of complications. In severe cases of classic MVP, complications include [[mitral regurgitation]] and [[infective endocarditis]]. | | '''Mitral valve prolapse''' ('''MVP''') is a [[valvular heart disease]] characterized by the displacement of an abnormally thickened [[mitral valve]] leaflet into the left atrium during [[systole]]. In its nonclassic form, MVP carries a low risk of complications. In severe cases of classic MVP, complications include [[mitral regurgitation]] and [[infective endocarditis]]. |
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| The [[mitral valve]], so named because of its resemblance to a bishop's miter, is the [[heart valve]] that prevents the backflow of [[blood]] from the left [[Ventricle (heart)|ventricle]] into the [[left atrium]]. It is composed of two leaflets (one anterior, one posterior) that close when the left ventricle contracts.<ref>{{cite web
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| | last = Women's Heart Foundation, Inc.
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| | first =
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| | title = Mitral Valve Prolapse
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| | url=http://www.womensheartfoundation.org/content/HeartDisease/mitral_valve_prolapse.asp
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| | accessdate = 2007-07-11}}</ref>
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| Each leaflet is composed of three layers of [[biological tissue|tissue]]: the ''atrialis'', ''fibrosa'', and ''spongiosa''. Patients with classic mitral valve prolapse have excess [[connective tissue]] that thickens the spongiosa and separates [[collagen]] bundles in the fibrosa. This is due to an excess of [[dermatan sulfate]], a [[glycosaminoglycan]]. This weakens the leaflets and adjacent tissue, resulting in increased leaflet area and elongation of the [[chordae tendineae]]. Elongation of the chordae may be associated with chordae rupture, and is commonly found in the chordae tendineae attached to the posterior leaflet. Advanced lesions — also commonly involving the posterior leaflet — lead to leaflet folding, inversion, and displacement toward the [[left atrium]].
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| ==Mitral valve prolapse syndrome==
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| '''Mitral valve prolapse syndrome''' ('''MVP Syndrome'''), also referred to as '''mitral valve prolapse dysautonomia''', is thought to represent an imbalance of the [[autonomic nervous system]] in association with mitral valve prolapse. The underlying etiology that causes both autonomic dysregulation and the structural abnormalities present in mitral valve prolapse is unknown. Most patients who suffer from mitral valve prolapse syndrome may have an underlying [[dysautonomia]] as the cause of their symptoms. In particular, supraventricular arrhythmias such as those observed with MVP syndrome are associated with increased parasympathetic tone.<ref name="Terechtchenko-2003">{{cite journal | author=Terechtchenko L, Doronina SA, Pochinok EM, Riftine A. | title=Autonomic tone in patients with supraventricular arrhythmia associated with mitral valve prolapse in young men. | journal=Pacing Clin Electrophysiol | year=2003 | volume=26 | issue=1 Pt 2 | pages=444-6 | pmid=12687863}}</ref>
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| Symptoms generally attributed to MVP syndrome include [[palpitations]], [[shortness of breath]], and [[fainting|syncope]]. Because of the low specificity of these symptoms, and the fact that there is significant overlap in the causes of these symptoms with sequelae of significant [[mitral regurgitation]] often seen with mitral valve prolapse, MVP syndrome is most likely over-diagnosed.<ref name=Fogoros>{{cite web
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| | last = Fogoros
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| | first = Richard N.
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| | title = Mitral Valve Prolapse (MVP)
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| | url=http://heartdisease.about.com/library/weekly/aa073100b.htm
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| | work=Heart Disease
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| | publisher=About.com
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| | accessdate = 2007-07-11}}</ref> The uncertainty regarding the frequency of this syndrome may in part be due to the fact that there is no consensus criteria to diagnose MVP syndrome.
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| ==References== | | ==References== |