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Heart Murmur - Topic Overview

What is a heart murmur?

A heart murmur is an extra sound that the blood makes as it flows through the heart. Your doctor uses a stethoscope to listen to your heartbeat. When you have a heart murmur, your doctor can hear an extra whooshing or swishing noise along with your heartbeat.

It can be scary to learn that you or your child has a heart murmur. But heart murmurs are very common, especially in children, and are usually harmless. These normal murmurs are called "innocent" heart murmurs. There is nothing wrong with your heart when you have an innocent murmur. Up to half of all children have innocent murmurs.1 They usually go away as children grow.

Adults can have innocent murmurs too. Innocent murmurs are often found in adults over 50 years of age. Murmurs also happen when your blood flows harder and faster than usual—during pregnancy, for example, or a temporary illness, such as a fever.1

Sometimes, though, a heart murmur is a sign of a heart problem. This is called an abnormal heart murmur.

What causes an abnormal heart murmur?

Abnormal murmurs are signs of a heart problem. In children, abnormal heart murmurs are usually caused by problems they are born with, such as a heart valve that doesn't work right or a hole in the wall between two heart chambers.

In adults, abnormal murmurs are most often caused by damaged heart valves. Heart valves operate like one-way gates, helping blood flow in one direction between heart chambers as well as into and out of the heart. See a picture of blood flow through a normal heart camera.gif.

When disease or an infection damages a heart valve, it can cause scarring and can affect how well the valve works. The valve may not be able to close properly, so blood can leak through. Or the valve may become too narrow or stiff to let enough blood through. When a damaged heart valve cannot close properly, the problem is called regurgitation. When the valve can't let enough blood through, the problem is called stenosis.

Heart valves can be damaged by heart disease or by infections like rheumatic fever or endocarditis. The normal wear and tear that comes with aging can also cause some damage.

Some heart murmurs are caused by a thicker than normal heart. When the heart muscle grows too large, it can get in the way of normal blood flow and cause a murmur.

How is a heart murmur diagnosed?

Most heart murmurs are found during regular doctor visits. During exams, doctors listen to each part of the heartbeat, including any extra sounds, or murmurs, that may be there.

If a doctor hears a murmur, he or she can often tell whether it is innocent by how loud the noise is, what part of the heart it is coming from, and what kind of sound it is. He or she will also look for signs of a heart problem—for example, shortness of breath when the person is active, lightheadedness, a fast or irregular heartbeat, or a buildup of fluid in the legs or lungs. If your doctor thinks your murmur may be a sign of a problem, you will have tests to check your heart. You may also be sent to a heart specialist, called a cardiologist, for more tests.

  • An echocardiogram is a type of ultrasound test. It turns sound waves into pictures that show how well your heart is working.
  • An electrocardiogram, also called an EKG or ECG, checks the electrical activity of your heart. It translates your heart's electrical activity into line tracings on paper. The spikes and dips in the line tracings are called waves.
  • A chest X-ray shows the size and shape of your heart and the position and shape of your large arteries.
  • Cardiac catheterization can check for defects in the heart. A thin tube is inserted into an artery in your leg or arm. The tube, called a catheter, is slowly pushed up to your heart. A small amount of dye is injected, and the pictures show the heart chambers and valves as the dye moves through them.
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