Mitral Valve Prolapse

Mitral Valve Prolapse is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • Mitral valve prolapse (MVP) is a systolic billowing of one or both mitral leaflets into the left atrium (LA) during systole ± mitral regurgitation (MR).
  • More specifically, MVP is a single or bileaflet prolapse of at least 2 mm superior displacement into the LA during systole on the parasternal long-axis annular plane of the valve on echocardiogram ± leaflet thickening.
    • Classic: prolapse with >5 mm of leaflet thickening
    • Nonclassic: prolapse with <5 mm of leaflet thickening
  • Synonym(s): systolic click-murmur syndrome; billowing mitral cusp syndrome; myxomatous mitral valve; floppy valve syndrome; redundant cusp syndrome; Barlow syndrome

Epidemiology

Incidence
  • Predominant age: MVP has been described in all age groups.
  • Initial descriptions based on clinical examinations suggested a 2:1 female predominance. Using modern echocardiogram criteria, men and women are affected equally (1).
  • The most serious consequences of hemodynamically significant MR occur in patients age >50 years (1).

Prevalence
MVP is the most common valvular abnormality, affecting 2–3% of the general population (1).

Etiology and Pathophysiology

  • The pathology causing MVP is multifactorial and includes the following:
    • Abnormal valve tissue
      • Myxomatous degeneration: redundant layers of leaflet “hooding” the cords, chordal elongation, and annular dilatation
      • Myxoid leaflets are more elastic and less stiff than normal valves.
      • Chordal rupture is more common.
    • Disparity in size between the mitral valve and the left ventricle (LV)
    • Connective tissue disorders
  • MVP is often associated with variable degrees of MR which occurs in 9% of patients.
  • The degree of MR depends on the degree of leaflet thickening and amount of flail or partially flail segments (2). When this occurs, 10-year mortality is 37% (2).
  • Frequently, there is enlargement of the LA and LV.
  • Mitral annulus is often dilated.
  • Involvement of other valves may occur (tricuspid valve prolapse 40%, pulmonic prolapse and aortic prolapse 2–10%).
  • Possible increased vagal tone
  • Possible increased urine epinephrine and norepinephrine
  • MVP patients often have orthostatic hypotension and tachycardia.
  • Genetics causes proliferation of the spongiosa layer of the leaflets and fibrosis on the surface of them (1).
  • Thinning and elongation of chordae tendineae
  • The mitral valve differentiates during days 35 to 42 of fetal development, the same time as differentiation of the vertebrae and ribs.

Genetics
  • Familial MVP is inherited as an autosomal dominant trait but with variable expressivity and incomplete penetrance.
  • Two genetic loci identified
    • MMVP1 on chromosome 16p11.2–p12.1
    • MMVP2 on chromosome 11p15.4

Risk Factors

  • MVP is a primary cardiovascular disorder.
  • MVP is more likely to occur in patients with connective tissue disorders (see “Commonly Associated Conditions”).
  • Physical characteristics associated with MVP
    • Straight thoracic spine
    • Pectus excavatum
    • Asthenic body habitus
    • Low body mass index (BMI)
    • Scoliosis or kyphosis
    • Hypermobility of the joints
    • Arm span > height
    • Narrow anteroposterior (AP) diameter of the chest

Commonly Associated Conditions

  • Marfan syndrome (91% of Marfan syndrome patients have MVP, although large majority of MVP patients do not meet criteria for Marfan.)
  • Ehlers-Danlos syndrome
  • Hypertrophic cardiomyopathy
  • Pseudoxanthoma elasticum
  • Osteogenesis imperfecta
  • von Willebrand disease
  • Primary hypomastia
  • Graves disease
  • Rheumatic heart disease

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Citation

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TY - ELEC T1 - Mitral Valve Prolapse ID - 116386 ED - Baldor,Robert A, ED - Domino,Frank J, ED - Golding,Jeremy, ED - Stephens,Mark B, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116386/all/Mitral_Valve_Prolapse PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -