What is the mitral valve?

The mitral valve is a valve with two leaflets situated on the left-hand side of the heart. It is a one-way valve that allows blood to move from the top chamber of the heart (left atrium) to the bottom chamber  (the main pump – the left ventricle). 

What is mitral stenosis?

Mitral valve stenosis is a condition where there is thickening of the inlet (mitral) valve on the left side of the heart. This usually opens to let red oxygenated blood through the top chamber of the heart (the left atrium) into the bottom chamber of the heart (left ventricle). From there  it is pumped around the body.  In mitral stenosis this valve becomes thickened (stenosed) and it is then more difficult for blood to pass between the top chamber (left atrium) and  bottom chamber (left ventricle). This often leads to a build-up of pressure in the top chamber (left atrium) which backs up into the lungs and causes shortness of breath. The top chamber (left atrium) often becomes very enlarged due to this pressure build-up. This commonly leads to an irregular heartbeat known as atrial fibrillation.

What causes mitral valve stenosis?

Many years ago, a condition known as rheumatic fever was more common in the UK. In some patients with rheumatic fever the heart was affected, and this most commonly caused thickening of the mitral valve –  mitral stenosis.  Thankfully  rheumatic fever as a cause of mitral stenosis is rare now in the UK. The most common cause today is degeneration, where the valve becomes thickened and bony due to wear and tear. It is also possible to be born with an abnormal mitral valve and have congenital mitral stenosis.

How is mitral valve stenosis detected?

Mitral valve stenosis is often picked up incidentally when you have an echocardiogram for another reason. Sometimes it is picked up following a doctor hearing a murmur when listening to your heart with a stethoscope. Sometimes people will develop an irregular heart rhythm known as atrial fibrillation and mitral stenosis will be subsequently picked up on an echocardiogram or because they have had an echocardiogram for shortness of breath.

What are the symptoms of mitral stenosis?

Most people with mitral stenosis will not experience any symptoms. In patients with severe mitral stenosis then symptoms can include shortness of breath (on exertion), palpitations (often due to an irregular heart rhythm known as atrial fibrillation) and swelling of the ankles and legs. Often mitral stenosis can be silent and only cause symptoms when the body is under stress, such as during pregnancy or during the time where you are unwell for another reason, for example sepsis.

What tests will I need?

Most people with mitral stenosis will have an ECG and echocardiogram. Other tests outlined below may also be performed.

Electrocardiogram (ECG)

Stickers are placed on the chest and the electrical activity of the heart is recorded.

Echocardiogram (Echo or cardiac ultrasound)

During the test an ultrasound probe is placed on the chest and moving pictures of the heart are taken. The test takes around 30 minutes. 


This is an x-ray dye test of your heart performed under local anaesthetic. 

What are the treatment options available?

Most people with mitral stenosis will not require any treatment and will just require regular monitoring of their condition. 

If your mitral valve is severely narrowed and you develop symptoms, you may be referred for intervention on your mitral valve.

What interventional options are there? 

Most people requiring intervention on their mitral valve for mitral stenosis will need a heart valve replacement. Your surgeon will discuss the options for you which would include a mechanical (metal) or tissue (bioprosthetic) valve. In occasional cases when the valve is narrowed due to rheumatic heart disease there may be an option for a procedure known as a balloon mitral valvuloplasty. This is a keyhole procedure where a tube is placed in the vein via the groin under local or sometimes general anaesthetic. The tube is then moved up to the heart under x-ray guidance and a balloon is inflated across the mitral valve causing it to stretch.

What does heart valve surgery involve?

A series of tests before you are referred to a surgeon will decide whether you are suitable for heart valve surgery. 

During a mitral valve replacement, the existing mitral valve is removed and replaced by either a metal or tissue valve. Your surgeon will discuss which type of valve would be most suitable for you. 

Heart valve replacement involves a general anaesthetic and the use of a heart-lung bypass machine. You will be left with a scar down the centre of the chest.  You will usually spend 1-2 days after the operation in intensive care and are usually discharged from hospital 7-10 days after surgery.

Do I need to change my lifestyle?


As with any type of heart disease, it is important that you follow a healthy diet, keep your weight within a normal range and do not smoke. Most patients with mitral stenosis will be encouraged to take regular gentle exercise but you should check this with your doctor. As the symptoms of mitral stenosis can be exacerbated by pregnancy, it is important you have a full informed discussion with your specialist before becoming pregnant. If you become pregnant unexpectedly then it is important that you let your heart specialist know immediately as you may require close monitoring.

Patients with mitral stenosis are also advised to take good care of their teeth and skin to prevent the risk of heart valve infection (endocarditis), which is a rare but serious condition. 


It is important to take good care of your teeth by brushing twice a day and visiting your dentist for regular check-ups (at least once per year). If you have toothache or an abscess it is really important that you get treated for this quickly. Be sure  to tell your dentist you have a heart condition.


Keep your skin clean by washing regularly. Wash any cuts and grazes and keep them clean until they heal. See your GP if your skin becomes red or inflamed. Avoid cosmetic procedures (e.g. tattoos, body piercing, fillers etc) that involve breaking the skin.