What is a heart murmur?

A heart murmur is a sound made by the blood flowing through the heart's valves. It is often harmless but sometimes it can be a sign of a more serious heart condition. Find out what a heart murmur is and how it's diagnosed.

When a doctor listens to your heart through a stethoscope, they will be able to hear the regular sounds of the blood flowing through your heart's valves. If the sound is unusual or doesn't follow the regular pattern, it is called a heart murmur.

Many heart murmurs are harmless – this is called an "innocent heart murmur". Sometimes, however, murmurs can be a sign of a problem with your heart, which may need to be checked by a healthcare professional.

What causes a heart murmur?

A number of different things can cause a heart murmur.

Many cases will be innocent, but some heart murmurs are caused by a problem with the heart valves. Sometimes people have been born with a heart valve issue. Alternatively, a heart murmur can develop as a result of:

  • stiffening or hardening of heart valves due to age, wear and tear (stenosis), which interrupts normal flow of blood through the valves
  • a heart attack
  • infection of the heart valves
  • long term effects of rheumatic fever

Other causes of a heart murmur include:

  • congenital heart conditions (heart conditions that you’re born with)
  • pregnancy
  • fever
  • extreme physical exercise
  • rapid growth
  • anaemia
  • over-active thyroid gland

How is a heart murmur diagnosed?

A heart murmur is usually picked up by your doctor when they're listening to your heart through a stethoscope.

If your doctor thinks your heart murmur is caused by a condition that needs treatment, he or she may order an echocardiogram (echo) and electrocardiograph (ECG), and refer you to a cardiologist for further assessment.

A CT scan and MRI may also be needed to find out more about your heart's structure.

Does a heart murmur need treatment?

A heart murmur itself doesn't need to be treated. However, you may need treatment for the heart condition that is causing your heart murmur, especially if you are having any symptoms (problems caused by the condition, like those listed below).

The treatment you’ll need will depend on the condition and the symptoms you have.

I've got a heart murmur – now what?

Some people will have a heart murmur their whole lives without needing treatment. In many cases a heart murmur is harmless (innocent murmur).

However, you need to tell your doctor if you experience any of the following symptoms (even if you've been told your murmur is innocent):

  • chest pain
  • trouble doing usual activities/exercise
  • shortness of breath
  • sudden weight gain
  • ankle swelling
  • dizziness or fainting
  • extreme tiredness
  • fever or night sweats
  • any symptoms that are out of the ordinary and causing you concern.
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