Mitral Valve Prolapse

Basics

Description

  • Bulging of 1 or both of the mitral valve leaflets into the left atrium during systole
  • Occurs when the leaflet edges of the mitral valve do not coapt
  • Commonly due to abnormal stretching of 1 of the mitral valve leaflets during systole:
    • Myxomatous proliferation of the spongiosa layer within the valve causing focal interruption of the fibrosa layer
    • Excessive stretching of the chordae tendineae, leading to traction on papillary muscles
  • Theoretical explanations for associated chest pain:
    • Focal ischemia from coronary microembolism due to platelet aggregates and fibrin deposits in the angles between the leaflets
    • Coronary artery spasm
  • Mitral regurgitation (MR) may occur in some patients
  • Age of onset is 10–16 yr
  • Female > male (3:1)
  • Typically benign in young women, whereas men >50 yr tend to have serious sequelae and more often develop severe regurgitation requiring surgical intervention
  • Can be identified by ECG in 2–4% of the general population and in 7% of autopsies
  • A variety of neuroendocrine and autonomic disturbances occur in some patients

Etiology

  • Primary mitral valve prolapse (MVP):
    • Absence of underlying connective tissue disease
    • May be sporadic or familial
    • Prevalence is 30–50% in 1st-degree relatives
    • Most commonly transmitted as an autosomal dominant trait with incomplete penetrance
  • Secondary MVP:
    • Associated with connective tissue disorders:
      • Marfan syndrome
      • Relapsing polychondritis
      • Ehlers–Danlos syndrome (ie, types I, II, IV)
      • Osteogenesis imperfecta
      • Pseudoxanthoma elasticum
      • Stickler syndrome
    • Associated with congenital vertebral or heart disease such as Ebstein anomaly
    • Diseases without myxomatous degeneration:
      • Systemic lupus erythematosus
      • Polyarteritis nodosa
      • Polycystic kidney disease
      • von Willebrand syndrome
      • Duchenne muscular dystrophy
    • Flail leaflet without myxomatous degeneration:
      • Myocardial infarction
      • Infective endocarditis
      • Acute rheumatic fever
      • Hypertrophic cardiomyopathy
      • Myxoma
      • Mitral annular calcifications
      • Trauma

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