Mitral valve prolapse pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Pathophysiology
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 into the left atrium. It is composed of two leaflets (one anterior, one posterior) that close when the left ventricle contracts.[1]
Each leaflet is composed of three layers of 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.
Associated Conditions
Mitral valve prolapse syndrome
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.[2]
Symptoms generally attributed to MVP syndrome include palpitations, shortness of breath, and 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.[3] 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.
References
- ↑ Women's Heart Foundation, Inc. "Mitral Valve Prolapse". Retrieved 2007-07-11.
- ↑ Terechtchenko L, Doronina SA, Pochinok EM, Riftine A. (2003). "Autonomic tone in patients with supraventricular arrhythmia associated with mitral valve prolapse in young men". Pacing Clin Electrophysiol. 26 (1 Pt 2): 444–6. PMID 12687863.
- ↑ Fogoros, Richard N. "Mitral Valve Prolapse (MVP)". Heart Disease. About.com. Retrieved 2007-07-11.