What is a heart murmur?

The heart makes sounds as it beats. These sounds happen 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. There are 2 types of systolic murmurs: ejection murmurs (because of forward blood flow as the heart pumps) and regurgitant murmurs (backward blood flow into 1 of the chambers of the heart as the heart pumps).

• 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.

• Times of rapid growth in children.

Normally, the blood flows from 1 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.

• Hypertrophic obstructive cardiomyopathy. This is a thickening of the walls of the pumping chambers of the heart.

These conditions can cause turbulent movement of blood through the heart. The flow makes abnormal sounds or a murmur that is heard with a stethoscope when your doctor 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 doctor 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.

• Chronic cough.

How is a heart murmur diagnosed?

To diagnose a heart murmur, your doctor will first ask about your health history. They will also listen to your heart. Your doctor 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 doctor 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 test creates an image of your heart and lungs.

• Electrocardiogram. This test shows the electrical activity and 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. The sound waves become images on a video screen. Your doctor can then see a moving picture of your heart. The test shows how your 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 echocardiogram (TEE). This is a special type of echocardiogram. It can provide even more detailed information about your heart valves. But a TEE is somewhat more involved than a surface echo as it needs a probe to be passed into your esophagus. So a surface echo test is often done first.

• Cardiac MRI. This uses strong magnets and radio waves. A cardiac MRI scan can show problems with heart structure, blood flow problems, or tissue damage.

• Cardiac CT scan. This uses X-rays and a computer. A cardiac CT scan can show problems with heart structure, especially if there is damage to blood vessels.

How is a heart murmur treated?

An innocent heart murmur doesn't 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. Choices 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 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 contact my doctor?

Contact your doctor or get medical care right away if:

• You have chest pain that is a lot like what you have felt in the past.

• You have mild shortness of breath.

• You feel a fluttering heartbeat (palpitations).

• You have a fever of 100.4°F (38°C) or higher, or as directed by your doctor.

• Your symptoms don’t get better with treatment, or they get worse.

• You have new symptoms.

Call 911 or get medical care right away if:

• You have new, major, or different chest pain.

• You have major shortness of breath.

• You have major palpitations.

• You feel lightheaded or like you may faint.

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 doctor can hear a murmur with a stethoscope.

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

Next steps

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

• 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 doctor 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 directions your doctor gives you.

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

• 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 doctor if you have questions, especially after office hours or on weekends.