A heart murmur is an abnormal sound your heart makes when it beats, often sounding like a whooshing or swishing noise. You can’t hear it normally, but your provider can listen to a heart murmur using a stethoscope. Heart murmurs can occur due to turbulent blood flow in or near the heart, usually caused by a structural problem or a condition that affects your heart valve or heart muscle.

There are two main types of heart murmurs: innocent and abnormal. Innocent murmurs are common and typically harmless. They are often found in children and may disappear as they grow older. Abnormal murmurs are more concerning because they may be a sign of an underlying heart condition and require further medical evaluation and treatment.

Structural problems in the heart can often cause a heart murmur. In most cases, these structural problems are congenital, meaning a person is born with them.

You can develop a congenital heart defect in the septum, which is the wall that separates the right and left sides of the heart. Holes in the wall of the septum can cause abnormalities. When there’s a hole in the wall of the upper chambers of the heart, it’s called an atrial septal defect. If the hole is located in the heart’s lower chambers, it’s known as a ventricular septal defect. These holes can affect how blood flows in and through your heart.

Another structural problem that can be present at birth is called patent ductus arteriosus. In this case, a blood vessel (called ductus arteriosus) that carries blood past the baby’s lungs before birth does not properly close after the baby is born. This can cause abnormal blood flow as well as a heart murmur.

Several valves in the heart aid with blood movement and direction. These include the aortic, pulmonary, mitral, and tricuspid valves. A heart murmur can occur when one of these valves does not function properly.

Aortic Valve

The aortic valve sits between the left ventricle (the heart’s lower left chamber) and the aorta (the main artery in the heart). A heart murmur can happen when this valve doesn’t function properly. In many cases, aortic valve stenosis is the culprit. This condition eventually restricts blood flow between the heart’s left ventricle and the aorta. A person can be born with this condition, but the risk of this condition also increases with age.

Aortic regurgitation can also cause a heart murmur. This happens when the aortic valve doesn’t properly close between heartbeats. This can cause blood to flow backward. Symptoms don’t always occur with this condition, but if they do, you may experience chest pain, shortness of breath, fatigue, fainting, and swelling in the legs, feet, or abdomen.

Mitral Valve

The mitral valve lies between the heart’s left atrium (upper left chamber) and left ventricle (lower left chamber). If the mitral valve narrows, you can have restricted blood flow. Mitral valve stenosis and mitral valve regurgitation can both affect your mitral valve.

Stenosis causes symptoms like shortness of breath, chest pain, and fluid build-up. Regurgitation can also called shortness of breath, as well as heart palpitations, coughing, and increased urination at night.

Pulmonary Valve

The pulmonary valve sits between the right ventricle of the heart and the pulmonary artery, which sends blood to the lungs. Heart murmurs can often occur due to pulmonary valve stenosis or regurgitation. Pulmonary valve stenosis is a condition that you can be born with. Symptoms may not occur until the narrowing of the valve is more severe but may include a bluish skin hue, poor appetite, and shortness of breath.

In pulmonary valve regurgitation, the valve doesn’t close properly, allowing blood that moves into the lungs to leak back into the heart’s right ventricle. This may cause symptoms such as shortness of breath and chest pain. As the condition progresses, the bottom right chamber of the heart may also grow larger.

Tricuspid Valve

The tricuspid valve lies between the heart’s right-side chambers. Like each of the heart’s other valves, this valve also can have either narrowing or blood flow issues. Tricuspid stenosis is a rare condition and usually occurs with other valve conditions like mitral valve stenosis.

Symptoms include fatigue, fainting, swelling in the legs and feet, trouble breathing, and lower urine output. With tricuspid regurgitation, however, you may also experience pulsing in the neck veins.

Valve problems often cause heart murmurs, but problems with the heart muscle itself can also lead to a murmur. Hypertrophic cardiomyopathy occurs when the heart muscle becomes thicker than it should. This condition can be passed down from one generation to the next in families.

While symptoms don’t always occur, you can develop chest pain, dizziness, fatigue, palpitations, and fainting spells (usually during exercise) as it progresses.

Research has found that heart murmurs are sometimes due to genetic mutations while a baby grows in the womb. Heart murmurs themselves are not hereditary, but some of the conditions that cause heart murmurs can be—such as aortic and pulmonary valve stenosis. Having a family history of some heart muscle diseases can also increase the risk of a heart murmur.

A heart murmur tends to be common in children and can develop before a baby is born. It’s likely more noticeable during a routine physical exam for an infant or child. This type of heart murmur can stay with a child as they get older or go away over time.

Abnormal heart murmurs can occur in both children and adults. They usually occur when there is an underlying heart condition. When this happens, a healthcare provider will likely want to run diagnostic tests to determine the cause, which may be a condition that affects the heart’s structure, valves, or muscle tissue.

Anyone can develop a heart murmur, but the following factors can increase your risk:

• A congenital heart defect
• Afamily history of heart defects or murmurs
• A diagnosis for a heart condition such as valve stenosis (narrowing of the valve) or regurgitation (blood leaking from the valves)

A heart murmur is an unusual whooshing or swishing sound heard during a heartbeat. It occurs because of turbulent blood flow in or near the heart, which can be caused by a problem with the heart’s structure, valves, or muscle tissue.

People who are born with a congenital heart defect, have a family history of heart murmurs, or live with a heart condition (such as stenosis or regurgitation) have a higher risk of developing a heart murmur.