What is a heart murmur?

During a physical exam, your doctor listens to your heart with a stethoscope.

Normal heart sounds

The doctor listens to your heart at different places on your chest to hear the sounds your heart valves make as blood travels through your heart. Normally, the heart beat has two sounds – lub-dub. The first sound is heard as the mitral and tricuspid valves close. The second heart sound is the aortic and pulmonic valves snapping shut.

Heart murmur

A heart murmur is a swishing sound heard when there is turbulent or abnormal blood flow across the heart valve.

Causes of heart murmurs

• Valvular heart disease is the most common cause of a heart murmur.
  • Valve stenosis – a narrow, tight, stiff valve, limiting forward flow of blood.
  • Valve regurgitation – a valve that does not close completely, allowing backward flow (a "leaky" valve)

The abnormal changes to the valve cause the abnormal heart sound (murmur).

• Other causes of heart murmurs include:
  • Hypertrophic cardiomyopathy
  • Septal defect

• Functional causes for heart murmurs

  Murmurs can be caused by increased blood flow across the valve related to other medical conditions without valvular heart disease, such as:

  • Anemia
  • Hyperthyroidism

• Innocent murmurs

  Murmurs can be present without any medical or heart conditions. Two common examples include:

  • Childhood murmurs
  • Pregnancy

Important information about heart murmurs

It is important to have regular physical exams to detect any abnormal heart sounds. If a murmur is heard, further evaluation will be required to determine why the murmur is present, which valve is involved, and the severity of the problem.

If the murmur is due to a heart valve problem:

• Follow-up with a cardiologist will be required to evaluate the progression of the valve disease.
• Most people who have a heart murmur require measures to prevent valve infection. These include:
  • Tell all your doctors and dentist you have valve disease
  • Call your doctor if you have symptoms of an infection
  • Take good care of your teeth and gums
  • Take antibiotics before you undergo any procedure that may cause bleeding
  • A wallet card may be obtained from the American Heart Association with specific antibiotic guidelines. Call your local American Heart Association office or nationally, 1-800-AHA-USA1 or go to http://www.americanheart.org/.*

For more information:

• Valve Disease
• How to find a doctor if you have valve disease

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