There is also a separate article entitled Mitral Valve Disease.

• Mitral stenosis is when there is obstruction to flow through the mitral valve separating the left atrium and left ventricle of the heart.
• The obstruction occurs due to a structural abnormality of the valve.¹ Mitral stenosis increases left atrial and pulmonary arterial pressure (especially in tachycardia).
• Pulmonary hypertension can lead to right ventricular dilation and tricuspid regurgitation. Right ventricular failure results in raised jugular venous pressure, liver congestion, ascites and peripheral oedema.¹ Left ventricular function and cardiac output can be normal in isolated mitral stenosis.
• Static blood flow in the left atrium (worsened in atrial fibrillation) can cause thromboemboli.

Aetiology¹

Causes of mitral stenosis include:

• Rheumatic fever (the most common cause).
• Degenerative calcification (can occur in the elderly).
• Congenital mitral stenosis (secondary to parachute mitral valve or Lutembacher's syndrome).
• Inborn errors of metabolism (e.g. Hurler-Scheie syndrome, Fabry's disease).
• Systemic lupus erythematosus.
• Rheumatoid arthritis.
• Carcinoid syndrome.
• Infective endocarditis with large vegetations.
• Amyloid deposition in the mitral valve.

Presentation

Mitral stenosis often presents in the 30s and 40s and may be asymptomatic in the early stages.

• Breathlessness: progressive breathlessness is the main symptom. This can include shortness of breath on exertion, orthopnoea and paroxysmal nocturnal dyspnoea. Pulmonary oedema can be triggered by the onset of atrial fibrillation.
• Atrial fibrillation: palpitations due to atrial fibrillation may be the presenting feature.
• Systemic emboli: is a more rare presentation. Stroke, renal failure and myocardial infarction can occur.
• Haemoptysis: this may occur secondary to rupture of the bronchial veins due to raised left atrial pressure.
• During pregnancy: the increase in blood volume may make a previously asymptomatic woman develop symptoms.

Signs

• Malar flush on the cheeks.
• Raised jugular venous pressure.
• Laterally displaced apex beat.
• Right ventricular heave.
• Loud first heart sound with an opening snap in early diastole.
• A mid-late diastolic murmur, best heard, with the patient in the left lateral position, with the bell of the stethoscope (see separate article Heart Auscultation).
• Atrial fibrillation.
• Signs of right ventricular failure including hepatomegaly, ascites and peripheral oedema.

Investigations

• CXR: may show left atrial enlargement and interstitial oedema (Kerley A and B lines) if severe. Mitral valve calcification may be seen. There may be prominent pulmonary vessels with redistribution of pulmonary vasculature to the upper lobes.¹
• ECG: may reveal atrial fibrillation, left atrial enlargement and right ventricular hypertrophy. (See separate article ECG A Methodical Approach.)
• Echocardiography: this is essential to confirm diagnosis (leaflet thickening and restricted movement) and to assess severity.² It can also look for left atrial thrombus and measure ventricle and atrial sizes. The gradient across the valve and pulmonary artery pressure can be assessed. Transoesophageal echocardiography and exercise echocardiography may also be used.²
• Cardiac catheterisation: this is used less as techniques for echocardiography have improved.

Management

Treatment aims are to:¹

• Reduce the symptoms of breathlessness and pulmonary congestion.
• Control the ventricular rate if atrial fibrillation is present.
• Prevent thromboembolic complications.
• Ensure adequate prophylaxis against infective endocarditis.
• Reduce the recurrence of rheumatic fever.

Medical management

• Most asymptomatic patients with mild or moderate mitral stenosis are monitored with annual echocardiograms and clinical examination. They are advised to report symptoms and require infective endocarditis prophylaxis.
• Diuretics ± nitrates can help symptoms of breathlessness.²
• Cardioversion (electrical or pharmacological) can be carried out for recent-onset atrial fibrillation. Otherwise, long-term rate control for atrial fibrillation can be achieved with betablockers, calcium-channel blockers or digoxin. See separate Atrial Fibrillation article which discusses this.
• Anticoagulation (target INR is 2-3) is recommended if there is:²
  • Atrial fibrillation (permanent or paroxysmal).
  • Left atrial enlargement.
  • Thrombus present in the left atrium or a dense spontaneous echocardiographic contrast is seen on transoesophageal echocardiogram.
  • A history of embolism.
• Betablockers to reduce heart rate (and trans-mitral gradient) are especially useful during pregnancy, even in sinus rhythm, when clinical tolerance of mitral stenosis is poor.² They may also be helpful in the nonpregnant state. Heart-rate regulating calcium-channel blockers may also be used to slow heart rate and increase exercise tolerance.
• Prevention of endocarditis: see separate Prevention of Endocarditis article.
• Reducing the recurrence of rheumatic fever: the World Health Organization recommends that a long-term programme of regular antibiotics to prevent further group A streptococcal infection (penicillin normally) should be continued lifelong for severe valvular disease and after valve surgery.^3,4

Surgical management

See also separate article Mitral Valve Operations. Surgical options include:

• Percutaneous balloon valvotomy
• Open mitral valvotomy
• Mitral valve replacement

Complications

• Pulmonary hypertension
• Dilated left atrium
• Atrial fibrillation
• Thromboembolic events
• Right heart failure
• Infective endocarditis

Prognosis¹

• The reported 5-year survival rate of patients with symptomatic mitral stenosis who refuse valvotomy is only 44%.
• For patients with no symptoms or minimal symptoms, survival is greater than 80% at 10 years.
• When limiting symptoms occur, 10-year survival is less than 15% in patients with untreated mitral stenosis.
• When severe pulmonary hypertension develops, mean survival is less than 3 years.
• Most patients with severe untreated mitral stenosis die as a result of progressive heart failure but others may die from systemic or pulmonary embolism, or infection.
• The prognosis is much improved in patients who undergo surgical or percutaneous relief of valve obstruction; however, life expectancy is still shortened compared with that expected for age, largely because of the complications of mitral stenosis.

Prevention¹

• Primary and secondary prevention of rheumatic fever.
• Prevention of endocarditis.

Document references

1. Dima C et al; Mitral Stenosis, eMedicine, Nov 2010
2. Guidelines on the management of valvular heart disease, European Society of Cardiology (2007)
3. Cilliers AM; Rheumatic fever and its management. BMJ. 2006 Dec 2;333(7579):1153-6.
4. Rheumatic fever and rheumatic heart disease - report of a WHO expert consultation, World Health Organisation (WHO), Geneva, 29 Oct to 1 Nov, 2001; WHO Tech Rep Ser 2001; 923

Acknowledgements