Mitral stenosis !
In mitral stenosis the valve between the left atrium and left ventricle narrows, so blood backs up into the lungs. Rheumatic fever is the usual cause.
Updated 2026-11-01
Structures involved
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- Mitral anterior leaflet
- Mitral posterior leaflet
- Left atrium
- Left ventricle papillary muscles
- Left ventricle
- Pulmonary veins
- Pulmonary arteries
- Right ventricle
In embryology
In the clinical exam
- Cardiac auscultation: the areas and the order
- Heart sounds: S1, S2 and its splitting, S3 and S4
- Valve murmurs: the table to know
Why it happens
- Fibrosis in organs: TGF-β and the myofibroblast
- Hyperemia and congestion (the nutmeg liver, heart-failure cells)
- Systemic (arterial) thromboembolism
- Murmurs and the hemodynamics of valve disease
- The cardiac cycle
- Physiology of pulmonary edema
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What it is
Narrowing of the mitral valve opening that obstructs flow from the left atrium to the left ventricle during diastole. It is almost always a late consequence of rheumatic fever.
Who gets it
Rheumatic heart disease remains a major cause of valve disease in low- and middle-income countries, including parts of Colombia and Latin America, where mitral stenosis is still seen in young adults and pregnant women. In high-income countries it is rare and mostly degenerative in older people.
Causes
- Rheumatic heart disease (by far the most common cause)
- Degenerative mitral annular calcification in older adults
- Rare causes: congenital stenosis, radiation, carcinoid, lupus
Risk factors
- Previous rheumatic fever or untreated streptococcal pharyngitis in childhood
- Poverty and overcrowding
- Female sex (rheumatic mitral stenosis is more common in women)
Pathophysiology
Repeated rheumatic inflammation fuses the commissures and thickens and shortens the leaflets and chordae, giving a «fish-mouth» opening. The left atrium must generate higher pressure to fill the ventricle, so it dilates and pressure is transmitted back to the pulmonary veins and arteries, causing pulmonary congestion and, later, pulmonary hypertension and right heart failure. Tachycardia shortens diastole and sharply worsens symptoms.
Classification
- By valve area: normal about 4 to 6 cm²; severe at or below 1.5 cm²
- Rheumatic versus degenerative (calcific)
- Staging from at risk (A) to symptomatic severe disease (D)
Symptoms and signs
- Exertional dyspnoea, orthopnoea and paroxysmal nocturnal dyspnoea
- Fatigue and reduced exercise tolerance
- Palpitations from atrial fibrillation
- Haemoptysis
- Hoarseness from compression of the left recurrent laryngeal nerve by a large atrium (Ortner syndrome) or dysphagia
- Loud first heart sound, opening snap and low-pitched mid-diastolic rumble at the apex
- Symptoms that appear or worsen in pregnancy
Diagnosis
- Clinical
- History of rheumatic fever and progressive dyspnoea; on auscultation a loud S1, an opening snap and a diastolic rumble at the apex heard best in the left lateral position with the bell. A shorter interval between S2 and the opening snap suggests more severe stenosis.
- Tests
- ECG: left atrial enlargement (broad notched P wave, «P mitrale»), atrial fibrillation, right ventricular hypertrophy in advanced disease.
- Imaging
- Transthoracic echocardiography confirms the diagnosis and measures valve area, gradient and pulmonary pressure; transoesophageal echo excludes left atrial thrombus and assesses suitability for balloon valvotomy; chest X-ray may show a straightened left heart border and pulmonary congestion.
Differential diagnosis
- Left atrial myxoma
- Mitral regurgitation
- Austin Flint murmur of severe aortic regurgitation
- Other causes of pulmonary hypertension or heart failure
- Tricuspid stenosis
Goal of treatment
Relieve the obstruction when severe and symptomatic, control heart rate and congestion, prevent thromboembolism, and prevent recurrent rheumatic fever.
Treatment
- Medical
- Secondary prophylaxis of rheumatic fever with long-term penicillin (usually intramuscular benzathine penicillin) to prevent further valve damage.
- Medical
- Rate control with beta-blockers or nondihydropyridine calcium-channel blockers to lengthen diastole, and diuretics for congestion.
- Medical
- Anticoagulation with a vitamin K antagonist when there is atrial fibrillation, previous embolism or left atrial thrombus; direct oral anticoagulants are not the standard in rheumatic mitral stenosis.
- Procedure
- Percutaneous balloon mitral valvotomy (commissurotomy) is preferred for severe symptomatic stenosis with favourable anatomy and no significant regurgitation or atrial thrombus.
- Surgical
- Surgical commissurotomy or mitral valve replacement when the valve is heavily calcified, regurgitant or unsuitable for a balloon.
- Follow-up
- Regular echocardiography, anticoagulation monitoring (INR), and close joint follow-up with obstetrics during pregnancy.
Complications
- Atrial fibrillation
- Left atrial thrombus with stroke and systemic embolism
- Pulmonary oedema and pulmonary hypertension
- Right heart failure and functional tricuspid regurgitation
- Infective endocarditis
- Maternal and fetal complications in pregnancy
Prognosis
There is a long latent period after rheumatic fever, but once symptoms appear the disease progresses and survival falls without intervention. Balloon valvotomy or surgery gives good long-term results in suitable patients.
Prevention
- Prompt antibiotic treatment of streptococcal pharyngitis (primary prevention of rheumatic fever)
- Long-term penicillin prophylaxis after rheumatic fever
- Early echocardiographic detection in high-risk populations
Test yourself
Think of the answer, then tap the question to see it.
What is the most common cause of mitral stenosis worldwide?
Rheumatic heart disease after rheumatic fever.
What are the classic auscultation findings of mitral stenosis?
A loud S1, an opening snap and a low-pitched mid-diastolic rumble at the apex.
Why does tachycardia or atrial fibrillation worsen mitral stenosis?
It shortens diastole, so the left ventricle has less time to fill through the narrow valve and left atrial pressure rises.
Which anticoagulant class is standard for atrial fibrillation with rheumatic mitral stenosis?
Vitamin K antagonists (warfarin), not direct oral anticoagulants.
Which procedure is preferred for severe symptomatic mitral stenosis with favourable valve anatomy?
Percutaneous balloon mitral valvotomy.
Related conditions
- Rheumatic heart disease
- Atrial fibrillation
- Ischaemic stroke
- Heart failure
- Infective endocarditis
- Mitral regurgitation
- Aortic regurgitation
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Mitral stenosis: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Rheumatic heart disease (World Health Organization, 2026).
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