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# Mitral stenosis

In mitral stenosis the valve between the [left atrium](https://durgical.com/en/anatomy/left-atrium/) and [left ventricle](https://durgical.com/en/anatomy/left-ventricle/) narrows, so blood backs up into the lungs. Rheumatic fever is the usual cause.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Mitral anterior leaflet](https://durgical.com/en/anatomy/anterior-leaflet-of-left-atrioventricular-valve/)
- [Mitral posterior leaflet](https://durgical.com/en/anatomy/posterior-leaflet-of-left-atrioventricular-valve/)
- [Left atrium](https://durgical.com/en/anatomy/left-atrium/)
- [Left ventricle papillary muscles](https://durgical.com/en/anatomy/superior-papillary-muscle-of-left-ventricle/)
- [Left ventricle](https://durgical.com/en/anatomy/left-ventricle/)
- [Pulmonary veins](https://durgical.com/en/anatomy/pulmonary-veins/)
- [Pulmonary arteries](https://durgical.com/en/anatomy/right-pulmonary-artery/)
- [Right ventricle](https://durgical.com/en/anatomy/right-ventricle/)

## In embryology

- [Warfarin embryopathy](https://durgical.com/en/embryology/warfarin-embryopathy/)

## In the clinical exam

- [Cardiac auscultation: the areas and the order](https://durgical.com/en/clinical-exam/cardiac-auscultation-the-areas-and-the-order/)
- [Heart sounds: S1, S2 and its splitting, S3 and S4](https://durgical.com/en/clinical-exam/heart-sounds-s1-s2-and-its-splitting-s3-and-s4/)
- [Valve murmurs: the table to know](https://durgical.com/en/clinical-exam/valve-murmurs-the-table-to-know/)

## Why it happens

- [Fibrosis in organs: TGF-β and the myofibroblast](https://durgical.com/en/general-pathology/fibrosis-in-organs-tgf-and-the-myofibroblast/)
- [Hyperemia and congestion (the nutmeg liver, heart-failure cells)](https://durgical.com/en/general-pathology/hyperemia-and-congestion/)
- [Systemic (arterial) thromboembolism](https://durgical.com/en/general-pathology/systemic-thromboembolism/)
- [Murmurs and the hemodynamics of valve disease](https://durgical.com/en/physiology/murmurs-and-the-hemodynamics-of-valve-disease/)
- [The cardiac cycle](https://durgical.com/en/physiology/the-cardiac-cycle/)
- [Physiology of pulmonary edema](https://durgical.com/en/physiology/physiology-of-pulmonary-edema/)

## Show 1 more

- [The heart wall, valves and conduction tissue](https://durgical.com/en/histology/the-heart-wall-valves-and-conduction-tissue/)

## 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](https://durgical.com/en/anatomy/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](https://durgical.com/en/anatomy/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

## Red flags

- Sudden-onset atrial fibrillation with acute pulmonary oedema
- Stroke or limb ischaemia from embolism
- Decompensation during pregnancy or labour
- Signs of right heart failure (oedema, ascites, raised jugular venous pressure)

## 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](https://durgical.com/en/anatomy/region/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.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/mitral-stenosis/)

## Related conditions

- [Rheumatic heart disease](https://durgical.com/en/conditions/rheumatic-heart-disease/)
- [Atrial fibrillation](https://durgical.com/en/conditions/atrial-fibrillation/)
- [Ischaemic stroke](https://durgical.com/en/conditions/ischaemic-stroke/)
- [Heart failure](https://durgical.com/en/conditions/heart-failure/)
- [Infective endocarditis](https://durgical.com/en/conditions/infective-endocarditis/)
- [Mitral regurgitation](https://durgical.com/en/conditions/mitral-regurgitation/)
- [Aortic regurgitation](https://durgical.com/en/conditions/aortic-regurgitation/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Mitral stenosis: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/000175.htm) (MedlinePlus, US National Library of Medicine, 2026); [Rheumatic heart disease](https://www.who.int/news-room/fact-sheets/detail/rheumatic-heart-disease) (World Health Organization, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/conditions/mitral-stenosis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/mitral-stenosis/