Abnormal and "Innocent" Heart Murmurs

Video: Understanding Heart Murmurs, Aortic and Mitral Valve Problems

What causes heart murmurs?

Abnormal heart murmurs in adults are usually related to defective heart valves. Abnormal heart murmurs in adults may be related to:

Some heart murmurs, called innocent murmurs, may occur in children. They are not considered to be serious and may be caused by: 

Heart murmurs related to valve problems should receive follow-up care.

Not every murmur is associated with valve disease. Murmurs can also be caused by conditions that may temporarily increase blood flow such as:

  • Exercise
  • Pregnancy
  • Fever
  • Hyperthyroidism
  • Anemia
  • Rapid growth spurts in children

If a murmur is detected, follow-up tests may be recommended. Although some heart murmurs indicate heart valve problems, others are considered harmless. These are “innocent” murmurs.

What are innocent heart murmurs?

Innocent heart murmurs are harmless sounds made by the blood circulating normally through the heart's chambers and valves or through blood vessels near the heart. They can be common during infancy and childhood and often disappear by adulthood. They're sometimes known as "functional" or "physiologic" murmurs.

Some harmless murmurs require additional tests such as an electrocardiogram (ECG) or echocardiogram (echo) to rule out the possibility of a problem.

Are innocent heart murmurs normal?

Innocent murmurs are common in healthy infants, children and adolescents. Innocent murmurs also may disappear and then reappear. Read more about childhood heart murmurs.

Innocent murmurs don’t require medication, don’t create cardiac symptoms and don’t mean there is a heart problem or disease.

Most innocent murmurs disappear when a child reaches adulthood, but some adults still have them. When a child's heart rate changes, such as during exercise, excitement or fear, the innocent murmur may become louder or softer.

Download our printable information sheet: What Are Innocent Heart Murmurs? (PDF)

Diagnosing the Cause: Types of Heart Murmurs

Your health care provider 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. Loudness is graded from 1 to 6. A grade of 1 is very faint, heard only with a special effort. A grade 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 provider determine which heart valve is involved as well as the severity. 

Other tests may be done to decide if the murmur needs further investigation including:

As with most conditions, heart murmurs and any underlying problems can vary in severity and risk. 

Any time a murmur is suspected to be associated with a valve problem that may need treatment or repair, it’s wise to look for a qualified 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.

Video: Heart Murmurs and Valve Problems

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