What Is Mitral Valve Stenosis?

Mitral valve stenosis is a type of heart disease. Mitral stenosis is when the heart valve opening narrows, which restricts the flow of blood from the left atrium to the left ventricle, two chambers of the heart.

The mitral valve allows blood to flow only in one direction through the heart's chambers. When narrowing occurs, the valve is not able to open as much as it should, causing the heart to pump less oxygen-rich blood from the lungs to the rest of the body.

Mitral valve stenosis can be asymptomatic for many years. Read on to find out how to recognise the symptoms that do appear and learn about treatment.

Overview

Issues that arise with the mitral valve can affect the way blood flows through the rest of the body. Mitral stenosis also causes an increase in the volume and pressure of blood that remains in the left atrium, which over time, results in left atrial enlargement and fluid buildup in the lungs.

Causes of mitral valve stenosis

A common cause of mitral valve stenosis is rheumatic heart disease (a life-threatening condition resulting from rheumatic fever, an autoimmune inflammatory reaction to an infection). The infection can cause inflammation of the heart, resulting in the mitral valve thickening and hardening.  

Rheumatic heart disease is a very serious form of heart disease that is common among children and young adults in developing countries.¹ It develops after a streptococcal infection of the throat (strep throat), which passes easily between individuals in the same way as other typical respiratory infections.

Other causes of mitral valve stenosis include:

• Ageing – over time, calcium deposits can build up on the valves, hardening them and causing stenosis (narrowing of the valves). However, age-related stenosis is typically mild, requiring little to no treatment
• Systemic lupus erythematosus (lupus) – a chronic autoimmune disease which causes inflammation of organs, including the heart, in a potentially life-threatening way
• Radiation – radiation therapy to the chest as part of cancer treatments has been shown to cause heart disease in 10%-30% of treated patients. Post-radiotherapy valve disease is often not diagnosed until 22 years after treatment²

Signs and symptoms of mitral valve stenosis

Individuals with mild stenosis may not experience any symptoms at all. However, as symptoms of mitral valve stenosis gradually develop over many years, they may not always be obvious. 

When symptoms do occur, they can include:

• Shortness of breath – especially at rest, which may be relieved by sitting upright or standing
• Palpitations – a racing, pounding or fluttering heartbeat
• Fatigue – tiredness that starts to interrupt daily activities
• Chest pain
• Dizziness
• Abdominal swelling
• Coughing up blood
• Heart murmur – an irregular heart sound found on examination with a stethoscope

Signs of advanced mitral stenosis:

• Hepatomegaly – enlargement of the liver occurs if there is right-side heart failure
• Pulmonary hypertension – a rise in blood pressure in the vessels that supply the lungs
• Atrial fibrillation – an irregular heart rhythm

Management and treatment for mitral valve stenosis

There is no cure for mitral valve stenosis, and asymptomatic patients may not require treatment. However, available treatments can help to alleviate symptoms.

• Antibiotics – the primary preventative treatment choice to reduce new cases of rheumatic fever and improve symptoms
• Diuretics (water tablets) – used to help reduce the amount of fluid in the body
• Beta-blockers or calcium channel blockers – help with symptoms associated with an elevated heart rate, which can arise from atrial fibrillation
• Anticoagulant medication (blood thinners) – can help prevent strokes and are recommended for individuals with atrial fibrillation and a history of blood clots
• Percutaneous mitral balloon valvuloplasty (PMBV) – a surgical procedure for patients with pulmonary hypertension and moderate to severe stenosis (with or without symptoms). A tube with a balloon attachment is fed through a blood vessel until it reaches the mitral valve, and inflating the balloon widens the narrowed valve
• Mitral valve replacement surgery – reserved for symptomatic moderate to severe stenosis patients where PMBV is not possible

Diagnosis of mitral valve stenosis

Mitral valve stenosis is often diagnosed following the presentation of symptoms; the diagnosis can be done through non-invasive or invasive tests.

Non-invasive tests include:

• Electrocardiogram (ECG/EKG) – monitors the heart's electrical activity and can detect signs of pulmonary hypertension and irregular heart rhythms
• X-rays – can detect early stages of mitral valve stenosis, such as dilation of the blood vessels supplying the lungs, and chronic stage stenosis, such as enlarged heart chambers 
• Echocardiogram – an ultrasound of the heart that can assess the severity of the mitral valve stenosis, valve leaflet thickness, mobility and calcification

Invasive tests include:

• Cardiac catheterisation – a thin tube is fed through a blood vessel to investigate the severity of mitral valve stenosis when non-invasive tests are inconclusive

Risk factors

The risk of developing mitral valve stenosis can be increased by;

• Ageing
• Untreated strep throat (rheumatic fever)
• Congenital heart disease (present from birth)
• Radiation therapy for some cancer treatments directed at the chest

Complications

• Pulmonary hypertension – high blood pressure in the blood vessels of the lungs
• Heart failure – when the heart is not able to pump enough blood to meet the body's demand
• Stroke – occurs when a blood clot blocks the flow of blood in the brain
• Endocarditis – an infection of the lining of the heart, which can be fatal

FAQs

How can I prevent mitral valve stenosis?

Congenital mitral valve stenosis starts at birth, so it cannot be prevented. Similarly, stenosis due to age cannot be prevented either. However, maintaining a healthy lifestyle can delay the onset. 

Treating infections, especially bacterial infections like strep throat, and following medical advice can prevent further complications.

How common is mitral valve stenosis?

In developed countries, mitral valve stenosis is uncommon and mainly observed in older adults. However, the prevalence is much higher in developing countries where access to medications such as antibiotics to prevent rheumatic fever is limited, and diagnosis is also more common in younger adults.¹

When should I see a doctor?

It is advisable to see a doctor for medical advice if any of the symptoms of mitral valve stenosis develop.

Summary

Mitral valve stenosis is characterised by a thickening and narrowing of the heart valve opening. It can go undiagnosed for many decades and is commonly caused by untreated rheumatic fever, although it can also be congenital.

Although the prevalence of this disease is declining in developed countries, it is still prevalent in the developing world, especially among young adults. 

Symptoms can include dizziness, shortness of breath, palpitations or more severe pulmonary hypertension. Although no cure exists, treatment can vary from medications to invasive surgery.

References

1. Watkins DA, Johnson CO, Colquhoun SM, Karthikeyan G, Beaton A, Bukhman G, et al. Global, regional, and national burden of rheumatic heart disease, 1990–2015. N Engl J Med [Internet]. 2017 Aug 24 [cited 2023 May];377(8):713–22. Available from: http://www.nejm.org/doi/10.1056/NEJMoa1603693

2. Copeland KA, Hosmane VR, Jurkovitz C, Kolm P, Bowen J, DiSabatino A, et al. Frequency of severe valvular disease caused by mediastinal radiation among patients undergoing valve surgery in a community-based, regional academic medical center: radiation-induced valve disease. Clin Cardiol [Internet]. 2013 Apr [cited 2023 Jun];36(4):217–21. Available from: https://onlinelibrary.wiley.com/doi/10.1002/clc.22106

This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Samantha Kamema

MSc – Preventative Cardiovascular Medicine, University of South Wales

Samantha is a Cardiac Physiologist with a passion for health, research and educating/ empowering the public into making informed decisions about their health and wellbeing. She has over 11 years of experience in healthcare having worked in both the NHS and private sector covering various fields. Currently exploring medical writing and medical communications.

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