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

• Fever

• Exercise

• Pregnancy

• Anemia

• Overactive thyroid gland

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.

Heart murmurs don't usually 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. Symptoms can include:

• Feeling weak or tired

• Shortness of breath, especially with exercise

• Chest pain

• Fast, pounding, or skipping heartbeat

• Swollen ankles, feet, abdomen

• Feeling dizzy or faint

• Poor feeding and failing to grow normally (babies only)

An innocent heart murmur doesn't usually 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. If a heart murmur is because of something that is causing or could cause problems later, then it may need treatment.

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

• Medicines to help relieve symptoms

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

• Procedures or surgery to fix a hole in the heart

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

• Heart failure, which means the heart is too weak to pump well

• Abnormal heart rhythm (arrhythmias)

• Blood clots and stroke

• Fainting

• Heart attack

• Sudden cardiac arrest (when the heart suddenly stops beating)

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

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

• Chills

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

• New symptoms

An innocent heart murmur is caused by mild turbulence (or rapid flowing blood) in the heart. This is normal and does not mean there is a problem. These murmurs often disappear over time. But sometimes, they can last a lifetime without causing any problems. Causes for innocent murmurs (or rapid blood flow) may include:

• Exercise
• Pregnancy
• Illness (fevers)
• Rapid growth in childhood
• Anemia

A pathologic heart murmur is often caused by a structural heart defect. This can include:

• Septal defects. These are holes in the dividing walls of the heart that allow blood to pass through.

• Heart valve problems. This means valves that have trouble opening or closing.

• Artery-vein fistulas. These are abnormal connections between a blood vessel on the left side of the heart and a blood vessel on the right side of the heart.

• Backflow of blood through a valve. This is because of pressure or blood flow abnormalities.

Innocent heart murmurs cause no symptoms. Symptoms related to a pathologic heart murmur depend on the underlying cause of the murmur and its severity. They may include a chronic cough, shortness of breath, dizziness, fainting, and blueish lips and fingertips.

Your child's healthcare provider may detect a heart murmur during a physical exam. They can hear heart noises with a stethoscope. A heart murmur is classified by how loud it is, its location, when it occurs during the heart’s pumping cycle, the way it changes through the heartbeat, and its sound qualities. If the healthcare provider suspects the murmur is pathologic, your child may be referred to a pediatric cardiologist. This is a doctor who diagnoses and treats heart problems in children. The following tests may be done:

• Chest X-ray. This test takes a picture of the heart and lungs. The picture can show your child’s heart size and shape. It can show some problems that may occur in the heart or lungs.

• Electrocardiogram (ECG). During this test, the electrical activity of the heart is recorded to check for abnormal heart rhythms (arrhythmias) or problems with heart structure.

• Echocardiogram (echo). During this test, sound waves are used to create a picture of the heart. This test can show problems with heart structure or heart function. This includes showing how well the heart pumps, if the heart is enlarged, or if there are any valve problems.

An innocent heart murmur requires no treatment because it’s not caused by a heart problem. Treatment for a pathologic murmur depends on the underlying cause and its severity. The cardiologist will evaluate your child’s condition and discuss treatment options with you if needed.

Most innocent murmurs usually go away by the time children become teens or young adults. A murmur may also become louder or more noticeable, or even return if a child has a fever, is dehydrated, or has another cause of a fast heart rate. If pathologic heart murmurs aren’t diagnosed or treated, severe symptoms may result and cause serious health problems. These can include heart failure, arrhythmias, respiratory problems, or even death.