If your doctor says you have a heart murmur, it may cause some concern. Although many heart murmurs aren’t serious, checking a heart murmur out to ensure it’s not a sign of an underlying heart condition is still wise.
Read on to learn about heart murmurs — what they are, how they develop, and when you should worry about them.
What Is a Heart Murmur?
A heart murmur is a sound caused by blood flow within the heart. The murmur happens when blood flows through or within structures of the heart, such as the valves. Other structures can be involved as well. Murmurs are often described as making various sounds, such as “musical”, or “blowing”, or “harsh” sounds. A heart murmur is usually discovered by medical professionals using a stethoscope.
The heart has four chambers — two upper and two lower. There are valves between the upper and lower chambers, and there are valves between the lower chambers and the major blood vessels in the chest, which are the aorta and the pulmonary artery. The valves open and close with every heartbeat, allowing the blood to flow in only one direction.
A heart murmur can happen when a valve doesn’t close tightly and the blood flows backward. Or, if the heart valve is stiff or narrow, the blood causes the valve to vibrate producing a murmur.
Murmurs also happen when there are abnormal connections between the lower heart chambers (hole in the heart), or between the major blood vessels themselves.
Murmurs can also occur when the heart structure and valves are normal, especially in very healthy hearts that pump so strongly a sound is made as the blood exits the heart. This is called an “ejection murmur.”
Generally, murmurs in healthy hearts are called “innocent murmurs.”
Heart murmurs are common, especially in children. They often run in families. According to the American Heart Association, at least one-third of children will have a heart murmur between ages 1 and 14. In most cases, the heart murmur is “innocent” and usually disappears as the child ages.
Adults can also develop innocent heart murmurs.
However, as mentioned, a heart murmur can also indicate a more serious problem such as a faulty heart valve or structural problem with the heart.
Types of Heart Murmurs
Doctors grade heart murmurs on a scale of 1 to 6 based on their loudness. Grade 1 is the softest murmur, and 6 is the loudest. Your doctor can barely hear a grade 1 murmur with a stethoscope.
If the heart murmur is more intense, your doctor may feel it with the palm of their hand over your heart. If that’s the case, it means the murmur is grade 4 or higher.
A doctor can hear a grade 6 murmur through a stethoscope without even touching the chest.
Doctors also describe heart murmurs by the heartbeat stage where they hear them. There are three main types of heart murmurs.
- Continuous murmurs — a continuous heart murmur begins during the period when the heart is contracting (called systole). It continues until at least partway through the period when the heart is relaxing (called diastole).
- Diastolic murmurs — a diastolic murmur happens in between heartbeats. It occurs as the lower heart chamber relaxes and fills up with blood.
- Systolic murmurs — a systolic murmur happens as the lower heart chamber contracts and squeezes out blood.
What Causes Heart Murmurs?
Heart murmurs have different causes. They include:
- Birth defects — include holes in the heart (called ventricular septal defects); and patent ductus arteriosus, when blood flows abnormally between the aorta and pulmonary artery.
- Cardiac tumors — includes myxoma which is a rare, noncancerous tumor that can grow inside your heart and can obstruct blood flow. Cancerous heart tumors are extremely rare but can also cause murmurs.
- Defective heart valve (most common cause of abnormal murmur in adults)— if you have a heart valve that’s too tight or too loose, it can cause a heart murmur. A leaky valve can cause blood to flow in the wrong direction. A tight valve can decrease blood flow within, or while blood is exiting, the heart.
- Hypertrophic Cardiomyopathy — the heart muscle is too thick. This condition causes abnormal blood flow.
- Other health conditions — Murmurs may develop from fever, overactive thyroid glands, anemia, infections on valves, and even pregnancy.
- Rapid growth spurts — sometimes, children develop innocent heart murmurs during rapid growth periods. These heart murmurs usually go away on their own.
- Valve Replacement—the “new” valve will cause a murmur even when functioning normally. It will make a different murmur sound if it starts to fail.
How Serious Is a Heart Murmur?
Many heart murmurs are innocent, but others can indicate problems with your heart.
An innocent heart murmur doesn’t cause problems or need treatment. Your doctor can often tell if a heart murmur is innocent by listening to it through a stethoscope. Sometimes further testing is needed.
Many babies and children have innocent heart murmurs. They usually disappear by the time the child reaches puberty and don’t need treatment.
If your doctor hears an abnormal heart murmur, they will probably run further tests, especially if you have other symptoms or a family history of heart disease.
Diagnosing Heart Murmurs
Your doctor may detect a heart murmur during a routine exam. They’ll note the loudness and location of the murmur and what it sounds like. They’ll ask about your health history and if you have symptoms like shortness of breath, dizziness, or chest pain.
If your doctor thinks the heart murmur is a sign of an underlying heart condition, they may send you to a cardiologist (heart specialist). The cardiologist may run further tests. These might include:
- Echocardiogram (heart ultrasound).
- Chest x-ray.
- Electrocardiogram (EKG).
- Cardiac catheterization.
- Cardiac CAT scan
- Cardiac MRI
- Blood tests for infection (Blood Cultures)
- Tests for conditions like amyloidosis that can cause heart thickening
- Genetic tests in Hypertrophic Cardiomyopathy
Treating Heart Murmurs
Many heart murmurs don’t need treatment. Your doctor can tell you if your heart murmur is an “innocent” one.
If your heart murmur stems from another heart condition, your doctor will talk to you about treatment. Depending on the underlying problem, your doctor may prescribe:
- ACE inhibitors — lower blood pressure and help treat some leaking heart valves
- Beta Blockers—slow down the heart rate and are used to treat various heart valve issues
- Calcium Channel blockers—lower blood pressure and can treat some leaking heart valves
- Antibiotics — treat bacterial infections on valves
- Surgery — can help repair congenital defects, damaged valves, and cardiac tumors
- Non-surgical Valve Replacement or Repair