Heart Murmurs
Quick Facts
- A heart murmur is an unusual heart sound heard while listening to your heartbeat.
- Innocent heart murmurs don’t need treatment.
- Abnormal heart murmurs can be a sign of a heart problem. In adults, this usually involves defective heart valves.
- Clues about the cause of a murmur can be based on the loudness, location and quality of the murmur. Other tests may be used to see if treatment is needed.
What is a heart murmur?
A heart murmur is an unusual heart sound that a health care professional hears while listening to your heartbeat. Many heart murmurs are harmless. Those are called innocent murmurs. Abnormal heart murmurs may be a sign of an underlying heart problem that should be studied further.
What are innocent heart murmurs?
Innocent heart murmurs are not dangerous. They are harmless sounds made when the blood moves normally through the heart’s chambers and valves, or through nearby blood vessels.
These murmurs are common in babies and children. They often go away by the time someone becomes an adult. Innocent heart murmurs are sometimes called “functional” or “physiologic” murmurs.
About one-third to three-quarters of children will have an innocent murmur at some time between ages 1 and 14. They can come and go. Innocent heart murmurs may sound louder or softer when a child is excited or scared. This still doesn’t signal a cause for concern.
If a child’s doctor hears a murmur when listening to their heart with a stethoscope, they may recommend more testing to confirm it’s harmless. Unless testing suggests otherwise, no further steps may be needed.
Children with innocent murmurs:
- Don’t need to take medication
- Don’t have a heart problem or heart disease
- Don’t need to limit their activity
- Don’t need a special diet
- Can lead an active, healthy life
Most innocent murmurs disappear by adulthood, but some remain for life without causing problems.
Innocent murmurs can be caused by conditions that may temporarily increase blood flow, such as:
- Exercise
- Pregnancy
- Low red blood cells (anemia)
- Overactive thyroid (hyperthyroidism)
- Rapid growth spurts in children
What are abnormal heart murmurs?
Abnormal heart murmurs indicate that there’s something wrong with the heart’s structure or function. In adults, this usually involves defective heart valves.
Heart valve problems can include:
- A valve that has a smaller-than-normal opening and can’t open fully (stenosis)
- A valve that doesn’t close completely, causing blood to leak backward (regurgitation)
Heart valve problems can affect the:
- Aortic valve (aortic regurgitation, aortic stenosis)
- Mitral valve (chronic or acute mitral regurgitation, mitral stenosis)
- Pulmonary valve (pulmonary regurgitation, pulmonary valve stenosis)
- Tricuspid valve (tricuspid regurgitation, tricuspid stenosis)
Heart murmurs related to valve problems should receive follow-up care.
Abnormal heart murmurs may also be caused by a heart condition called hypertrophic cardiomyopathy.
In children, abnormal murmurs may be caused by:
- Abnormal pulmonary veins (anomalous pulmonary venous return)
- A hole in the wall between the heart’s upper chambers (atrial septal defect)
- A narrowed aorta (coarctation of the aorta)
- An unclosed hole in the aorta, the main body artery (patent ductus arteriosus)
- A hole between the heart’s lower chambers (ventricular septal defect)
How is the cause of a heart murmur diagnosed?
Your health care professional will investigate the root cause of the heart murmur. Clues about the cause can be based on the loudness, location and quality of the murmur.
A murmur that occurs when the heart muscle relaxes between beats is called a diastolic murmur. A systolic murmur occurs when the heart muscle contracts. Systolic murmurs are graded by intensity (loudness).
Loudness is graded from 1 to 6. A 1 is very faint, heard only with a special effort. A 6 is extremely loud and can be heard with a stethoscope even without touching the chest.
The location, duration and loudness of the murmur can help your health care professional determine which heart valve is involved and how severe it is.
Other tests may be done to decide if the murmur needs further evaluation, including:
Heart murmurs and any underlying problems can vary in severity and risk.
If a murmur is related to a valve problem that may need treatment or repair, it’s wise to find a health care professional with experience diagnosing and treating your condition. A specialist who regularly manages valve disease can assess your condition and offer treatment options.
