Heart Murmur

A heart murmur is a whooshing or swishing sound your heart makes when blood flows in a choppy or rough way through it. This sound may mean there’s a problem with your heart — often a valve issue. But for many people, it’s an “innocent heart murmur” that doesn’t need treatment because it’s harmless. An innocent murmur means your heart is healthy and working normally.

A healthcare provider can hear a heart murmur by listening to your heartbeat with a stethoscope, which makes the sounds loud enough to hear. They listen at different places on your chest and back.

A murmur isn’t a disease on its own. It’s a sound that gives your provider a clue about what’s happening in your heart.

What does a heart murmur sound like?

When your heart beats, valves open and close, allowing blood to flow. When the valves close, they produce two sounds: a “lub” and a “dub.”

If your heart makes a whooshing or swishing sound in addition to these sounds, that’s called a heart murmur. A murmur means blood is flowing fast or in a choppy way. This can happen in a healthy heart or in a heart with a problem.

Some murmurs are soft and difficult to hear. Others are loud. A murmur may also change when you sit up, lie down or take a deep breath.

How is a heart murmur diagnosed?

Your provider will listen to your heart with a stethoscope. They’ll note where on your chest the murmur is loudest and when exactly it happens during your heartbeat. This helps them decide if a murmur is innocent or a sign of a problem.

Healthcare providers talk about heart murmurs based on when they happen in a heartbeat:

• Systolic: Occurs when your heart muscle contracts (squeezes) to pump blood out
• Diastolic: Occurs when your heart muscle relaxes and fills with blood
• Continuous: Happens throughout the whole heartbeat, when your heart squeezes and when it relaxes

Diastolic murmurs usually mean there’s a heart problem. Continuous murmurs can be innocent, especially in children. But they can also be a sign of a problem. Most innocent murmurs are systolic.

Healthcare providers describe murmurs by how intense or loud they are. For systolic murmurs, they use a scale of one (you can barely hear it) to six (it’s so loud, you can hear it with the stethoscope off your chest). For diastolic murmurs, they use a scale of one to four.

Louder murmurs (three or higher) are more likely to be a sign of a problem. But how loud a murmur is doesn’t always match how serious the cause is.

Innocent heart murmur causes

Innocent heart murmurs are common and harmless. In fact, many children have one at some point. Murmurs often go away when you become an adult, but some last a lifetime.

Blood moving faster or with more force than usual through a healthy heart can cause an innocent heart murmur (also called functional or physiologic). In children, a thin chest wall also makes these sounds easier to hear.

This type of murmur is common during:

• Childhood
• Physical activity
• Fever
• Growth spurts
• Pregnancy
• The first few days after a baby is born

Abnormal heart murmur causes

Rough or abnormal blood flow through your heart causes a heart murmur. These abnormal heart murmurs are due to a heart problem or other condition, including:

• Low red blood cell number (anemia): When you don’t have enough red blood cells, your heart pumps harder and faster to get oxygen to your body. This extra blood flow can cause a murmur.
• Carcinoid syndrome: Some slow-growing tumors (neuroendocrine tumors) release hormones into your blood. Over time, these hormones can thicken and damage the valves on the right side of your heart and cause a murmur.
• Congenital heart disease: Your heart may have a structural problem that’s been there since birth. Examples include a hole in your heart wall (septal defect), a blood vessel that doesn’t close after birth (patent ductus arteriosus) or a narrow aorta (coarctation of the aorta).
• Endocarditis: This is an infection of the inner lining of your heart, usually involving the valves. It can damage valves quickly, causing a murmur, and needs treatment right away.
• Heart valve disease: This means one or more heart valves aren’t working right. For example, your mitral valve’s flaps may bulge backward, a valve may not open all the way (stenosis) or a valve may let blood leak in the wrong direction (regurgitation). Valve problems can happen with age, after rheumatic fever or because a valve formed differently before birth.
• Overactive thyroid (hyperthyroidism): Your thyroid gland makes too much thyroid hormone and makes your heart pump more blood than usual.
• Hypertrophic cardiomyopathy: This type of heart disease makes your heart muscle too thick. The thick muscle can partly block blood flow out of your heart, causing a murmur. This condition often runs in biological families.

How is a heart murmur treated?

Many heart murmurs don’t need any treatment. The innocent kind can go away and return. They may get louder when your heart beats faster. If you or your child has an innocent murmur, you don’t need medicine or limits on sports and other activities. You also don’t need antibiotics before dental work if you have an innocent murmur.

But if a more serious condition causes the murmur, you’ll likely need treatment for that. Treatments may include:

• Medications: Examples include antibiotics for endocarditis, medicines for your thyroid or a tumor, and heart medicines like water pills or beta-blockers to improve symptoms.
• Procedures: These could include a blood transfusion for severe anemia or a catheter-based procedure. In these procedures, a provider guides a thin tube (catheter) through a blood vessel to your heart. They can repair or replace a valve, close a hole in your heart or shrink thick heart muscle.
• Surgery: This can correct or replace a valve, remove tumors, fix a heart defect, remove the thickened part of your heart or remove your thyroid.

Heart murmur tests

Your healthcare provider can often tell a murmur is innocent just by listening with a stethoscope. If they’re not sure, or if the murmur could be a sign of a problem, they may order tests. Tests that can find the cause of a heart murmur are:

• Chest X-ray: This picture of the inside of your chest can show if your heart is bigger than normal or if there’s fluid in your lungs.
• Echocardiogram: This test uses sound waves to make images of your heart’s valves and chambers. It shows any problems with how blood moves through them. It’s the main test providers use to find the cause of a murmur.
• Electrocardiogram (EKG): This test shows your heart’s electrical activity, providing signs of certain heart problems.
• Blood tests: These can check for anemia, thyroid problems or an infection.
• Heart (cardiac) MRI: This test uses a strong magnet to make detailed pictures of your heart muscle and valves.
• Cardiac catheterization: In this minimally invasive test, a provider guides a thin tube through a blood vessel to your heart. It measures pressure inside your heart and shows how blood flows. You may need it if other tests don’t give enough answers, or before a valve surgery.

Can this symptom be prevented?

You can’t prevent many of the causes of heart murmurs. But you can lower your chances for some of them in these ways:

• Eat foods rich in iron, like lean meat, beans and leafy greens, if you have anemia.
• Brush and floss every day and see your dentist regularly. Healthy teeth and gums decrease the chances of valve infections.
• Get treatment for strep throat if your provider recommends it to prevent rheumatic fever, which can damage your heart valves.
• Don’t inject drugs. Injecting drugs increases the risk for infections inside your heart.

What are the possible complications or risks of not treating it?

Without treatment for the problem causing the heart murmur, the condition can lead to:

• Heart failure
• Kidney disease
• Liver disease
• Abnormal heart rhythms
• High blood pressure in your lungs
• Stroke
• Sudden heart death

Innocent murmurs don’t cause any of these problems.

When should this symptom be treated by a healthcare provider?

Seek medical attention if you or your child has any symptoms of a heart problem, including:

• Bluish skin, nails or lips
• Chest pain or pressure
• Racing or pounding of your heart, or skipped beats
• Shortness of breath
• Fainting or weakness
• Dizziness or feeling lightheaded
• Swelling in your feet, ankles, legs or belly
• Trouble feeding, sweating while feeding, fast breathing or not gaining weight with feedings (in babies)

If you have a known heart valve problem, call your provider if you get a fever that doesn’t go away.

If your provider finds that a murmur is a symptom of a heart problem, ask them to refer you to a specialist. For example, they can refer you to a cardiologist (heart doctor). Or they can refer you to a pediatric cardiologist for your child.