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Mitral Stenosis

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Overview

Mitral stenosis describes the narrowing of the mitral valve leading to obstructed blood flow through the mitral valve, which separates the left atrium and left ventricle of the heart. This obstructed flow results in increased pressures in the left atrium, pulmonary vasculature, and the right side of the heart.

Over time, continued increased left atrial pressure can lead to left atrial hypertrophy and atrial fibrillation.

Causes

Epidemiology

  • The prevalence of mitral stenosis secondary to rheumatic fever is lower in developed countries
  • The onset of mitral stenosis is generally in the 2nd and 3rd decades of life

Presentation

Patients may be asymptomatic before symptoms arise. Features include:

Signs on examination

  • Mid-late diastolic murmur that is louder in the left lateral position in expiration
  • Loud S1 heart sound and opening snap in early diastole
  • Malar flush on the cheeks
  • Orthopnoea – due to increased left atrial pressure
  • Elevated jugular venous pressure – suggests increased pressure in the pulmonary vasculature or right heart

Investigations

Overview

  • ECG:
    • May show atrial fibrillation
    • May show bifid P waves
  • Chest x-ray:
    • May show left atrial enlargement
    • May show features of pulmonary oedema (e.g. Kerley B lines)
  • Transthoracic echocardiogram:
    • Confirms mitral stenosis

Management

Overview

  • If atrial fibrillation is present: lifelong warfarin
  • If asymptomatic:
    • Monitor with regular echocardiography
  • If symptomatic – treat, options include:
    • Percutaneous mitral balloon valvotomy
    • Mitral valve surgery (e.g. valve replacement or commissurotomy)

Complications

Prognosis

  • If asymptomatic, 10-year survival is good
  • If symptomatic, 10-year survival is poor if untreated (~20%)

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