What is a heart murmur?

The heart makes sounds as it beats. These sounds occur as the heart valves open and close to allow blood to flow through the heart. A heart murmur is an extra noise heard during a heartbeat. The noise is caused when blood does not flow smoothly through the heart.

Heart murmurs can be innocent (harmless) or abnormal (caused by a heart problem). Types of murmurs are:

• Systolic murmur. This happens during a heart muscle contraction. Systolic murmurs are divided into ejection murmurs (because of blood flow through a narrowed vessel or irregular valve) and regurgitant murmurs (backward blood flow into one of the chambers of the heart).

• Diastolic murmur. This happens when the heart muscle relaxes between beats. Diastolic murmurs are from a narrowing (stenosis) of the mitral or tricuspid valves, or regurgitation of the aortic or pulmonary valves.

• Continuous murmur. This happens throughout the cardiac cycle.

What causes a heart murmur?

An innocent (also called functional) heart murmur can be a normal finding for many people. It may also be caused by:

• Fever

• Exercise

• Pregnancy

• Low red blood cell count (anemia)

• Overactive thyroid gland

• During times of rapid growth in children

Normally, the blood flows from one heart chamber to the next and valves close tightly to prevent blood from flowing backward. An abnormal heart murmur can be caused by heart problems such as:

• A damaged or diseased valve. The valve may be too narrow for blood to flow through easily. Or it may have problems opening or closing, and may leak blood backward.

• A hole in the heart (septal defect). This is a problem with the heart’s structure that a person is born with (congenital). It causes blood to leak through the wall that normally divides the left and right sides of the heart.

• Thickening of the walls of the pumping chambers of the heart (hypertrophic obstructive cardiomyopathy)

These conditions can cause turbulent movement of blood through the heart. This flow makes abnormal sounds or a murmur that is heard with a stethoscope when your healthcare provider does a physical exam.

What are the symptoms of a heart murmur?

Heart murmurs don’t often cause symptoms. They tend to be found when your healthcare provider is listening to your heart for another reason. People with an abnormal heart murmur may have symptoms of the problem causing the murmur. These can include:

• Feeling weak or tired

• Shortness of breath, especially with exercise

• Chest pain

• Fast, pounding, or skipping heartbeat

• Swollen ankles, feet, or belly (abdomen)

• Feeling dizzy or faint

How is a heart murmur diagnosed?

To diagnose a heart murmur, your healthcare provider will first ask about your health history. They will also listen to your heart. Your healthcare provider can hear a murmur with a stethoscope.

Some murmurs can be heard best when listening on the front of the chest. Others can be heard best when listening with a stethoscope on your back. Your healthcare provider may ask you to hold your breath so that the sound of your heart beating can be heard without the sounds of your breathing. You may also be asked to lie on your side or to stand and squat. This is to see how the chambers of the heart and valves react to more blood flow through the heart chambers and the heart valves.

Heart murmurs are most often completely normal. But sometimes they can be a sign of a heart problem. So you may also need some tests. These can help diagnose a heart valve problem and rule out any other disease you may have:

• Chest X-ray. This imaging test looks at your heart and lungs.

• Electrocardiogram. This test shows the rhythm of the heartbeat.

• Cardiac catheterization. This test looks inside the heart. It helps measure the pressure in the chambers, checks for leaky valves, and looks for problems in the heart’s arteries.

• Transthoracic echocardiogram (echo). This is a simple, painless test that bounces harmless sound waves off the heart. These sound waves become images on a video screen. Your healthcare provider can then see a moving picture of your heart. This test shows how the valves work. It can confirm whether a valve is narrowed or leaking. It can also show the size of the chambers and if your heart muscle pumps normally.

• Transesophageal echo (TEE). This is a special type of echo. It can provide even more detailed information about your heart valves. But a TEE is somewhat more involved than a surface echo as it requires a probe to be passed into your esophagus. So a surface echo is often the first test done.

How is a heart murmur treated?

An innocent heart murmur doesn’t often need treatment unless there is a clear cause, such as anemia. In such cases, treating the underlying cause should cure the murmur. In some cases, an innocent heart murmur may go away on its own.

Treatment for an abnormal heart murmur depends on the cause. Options may include:

• Medicines to help ease symptoms

• Procedures or surgery to fix or replace a diseased or damaged heart valve

• Procedures or surgery to fix a hole in the heart

What are possible complications of a heart murmur?

An innocent heart murmur has no complications. Complications of an abnormal heart murmur will vary depending on the cause. Possible complications include:

• Heart failure, when the heart is so weak it no longer pumps blood well

• Infection of the heart’s valves or inner lining (infective endocarditis)

• Blood clots and stroke

• Fainting

• Heart attack

• Sudden cardiac arrest, when the heart suddenly stops beating

When should I call my healthcare provider?

Call your healthcare provider right away if you have any of these:

• Chest pain that is a lot like what you have felt in the past

• Mild shortness of breath

• Slight feeling of fluttering heartbeat (palpitations)

• Fever of 100.4°F (38°C) or higher, or as directed by your healthcare provider

• Symptoms that don’t get better with treatment, or that get worse

• New symptoms

Key points about heart murmurs

• A heart murmur is an extra noise heard during a heartbeat. The noise is caused when blood does not flow smoothly through the heart.

• Heart murmurs can be innocent (harmless) or abnormal (caused by a heart problem).

• Some causes are fever, anemia, or heart valve disease.

• Heart murmurs don’t often cause symptoms.

• A healthcare provider can hear a murmur with a stethoscope.

• No treatment may be needed for an innocent heart murmur. An abnormal one may be treated with medicines or surgery.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.