What causes heart murmurs?
Problematic heart murmurs are most often related to defective heart valves. Some heart murmurs are not considered to be a problem and may be referred to as “innocent murmurs.” Valve disease-related heart murmurs can be either:
- Stenosis-related murmur
A heart valve with a smaller-than-normal opening (called a stenotic valve) can't open completely.
- Regurgitation-related murmur
A valve may also be unable to close completely. This leads to regurgitation, which is blood leaking backward through the valve when it should be closed.
Not every murmur is associated with valve disease. Murmurs can also be caused by conditions that may temporarily increase blood flow such as:
- Thyrotoxicosis (a diseased condition resulting from an overactive thyroid gland)
Your healthcare provider will probably investigate the root cause of the heart murmur. Clues about the cause can be explored based on the type of sound, duration, and when the murmur is heard during the heartbeat. Short, quiet murmurs are more likely to be benign (meaning they are harmless and no treatment is needed.)
Systolic Murmur: A murmur that occurs when the heart muscle contracts is called a systolic murmur.
Systolic murmurs are also graded by intensity (loudness) from 1 to 6. A grade of 1 out of 6 (1/6) is very faint, heard only with a special effort. A grade 6 out of 6 (6/6) is extremely loud, and can be heard with a stethoscope even when slightly removed from the chest.
Systolic murmurs can indicate:
Diastolic murmur: A murmur that can be detected when the heart muscle relaxes between beats is called a diastolic murmur.
Diastolic murmurs can indicate:
Short, quiet systolic murmurs are more commonly harmless or innocent. Long systolic murmurs, diastolic murmurs and continuous murmurs are more likely to indicate problems that need to be treated, although there are specific continuous murmurs that are also considered harmless.
As with most conditions, heart murmurs and any underlying problems will vary in severity and risk.
Seeking a Qualified Healthcare Provider or Specialist
Any time a murmur is suspected to be associated with a valve problem that may eventually need treatment or repair, it is wise to begin investigating your community for a qualified healthcare provider with experience at diagnosing and treating your heart condition.
If you are unsure about your risks, it is always appropriate to ask your primary healthcare provider whether or not they have broad experience with diagnosing and treating heart valve problems. When in question, a specialist who regularly deals with valve disease can give you your best assessment, and many healthcare providers may choose to bring in a specialist to the team.
This content was last reviewed on 02/18/13.