Mitral stenosis
DEFINITION
Mitral valve narrowing causing obstruction to blood flow from the left atrium to the ventricle.
AETIOLOGY
Most common cause is rheumatic heart disease (90%).
Rarer causes are congenital mitral stenosis, SLE, rheumatoid arthritis, endocarditis and atrial myxoma (rare cardiac tumour).
EPIDEMIOLOGY
Incidence is declining in industrialized countries because of declining incidence of rheumatic fever.
HISTORY
May be asymptomatic.
Presents with fatigue, shortness of breath on exertion or lying down (orthopnoea). Palpitations (related to AF).
Rare symptoms: Cough, haemoptysis, hoarseness caused by compression of the left laryngeal nerve by an enlarged left atrium.
EXAMINATION
May have peripheral or facial cyanosis (malar flush).
Pulse:
May be ‘thready’ or irregularly irregular (AF).
Palpation:
Apex beat is undisplaced and tapping. Parasternal heave (right ventricular hypertrophy and pulmonary hypertension)
Auscultation:
Loud first heart sound with opening snap.
Mid-diastolic murmur (presystolic accentuation if in sinus rhythm).
Evidence of pulmonary oedema on lung auscultation (if decompensated).
INVESTIGATIONS
ECG:
May be normal, broad bifid p wave (p mitrale) caused by left atrial hypertrophy, AF or evidence of right ventricular hypertrophy in cases of severe pulmonary hypertension.
CXR:
Left atrial enlargement, cardiac enlargement, pulmonary congestion; mitral valve may be calcified in rheumatic cases.
Echocardiography:
To assess functional and structural impairments. Transoesophageal
gives better valve visualization.
Cardiac catheterization:
Measures severity of heart failure.
MANAGEMENT
Medical:
Anticoagulation for AF. Treat dyspnoea and heart failure with diuretics. Antibiotic cover for dental/invasive procedures. Cardioversion of AF may be considered.
Surgical:
Mitral valvuloplasty, valvotomy or replacement if severe.
COMPLICATIONS
AF and systemic embolism, pulmonary oedema, pulmonary hypertension and right heart failure, infective endocarditis.
PROGNOSIS
Significantly worse if pulmonary hypertension or right heart failure develops.
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