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Mitral Valve Stenosis

Etiology

  • Most commonly due to rheumatic heart disease – Group A β-hemolytic strep
  • Rare – congenital; calcification/fibrosis in the elderly
  • Lutembacher’s syndrome – atrial septal defect + mitral valve stenosis

Pathophysiology

  • Normal MV orifice 5cm2. Can be reduced to 1cm2 in severe MVS (symptoms occur at <2cm2)
  • In rheumatic MVS the mitral valve orifice is slowly diminished due to
    • Progressive fibrosis
    • Calcification of the leaflets
    • Fusion of the cusps and subvalvular apparatus
  • Flow from LA to LV is restricted
  • LAP rises – leads to pulmonary venous congestion and SOB
  • Dilation and hypertrophy of LA
    • Filling of LV becomes more dependent on LA contraction
  • Any increase in HR shortens diastole when the MV is open
    • Produces a further rise in LAP (as more blood remains in LA)
  • Progressive dilation of LA can cause AF
    • AF + tachycardia → rapid rise in LAP → can lead to pulmonary oedema + HF
  • In contrast, slow rise in LAP leads to ↑PVR, which leads to Pulmonary HTN (PHTN)

Clinical features

  • Loud S1 – because forces that open and close the MV are increased as LAP increases
    • However S1 can be inaudible if valve is heavily calcified
  • Opening snap (normally MV opens silently)
  • Mid diastolic murmur – due to turbulent flow

Diagnosis

ECG

  • LA hypertrophy – AF, bifid P waves
  • RVH – RAD, tall R waves in V1

CXR

  • Enlarged LA (characteristic doming)
  • Calcified MV
  • Signs of pulmonary oedema

Echo (diagnostic)

  • Thickened immobile cusps
  • Enlarged LA
  • Reduced rate of diastolic filling of LV

Doppler

  • Turbulent flow across MV

Management

Medical

  • Anticoagulation – reduces risk of embolism
  • Digoxin, beta blockers, CCB – ventricular rate control for AF
  • Diuretics – for pulm congestion
  • Mitral balloon valvuloplasy and valve replacement
  • Valvuloplasty if criteria is filled (see box)
    • Follow up pts yearly to assess for re-stenosis
  • Valve replacement – if valve is rigid and calcified
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