A heart murmur is the sound of blood flow in the chest heard with the stethoscope. If it is heard elsewhere, it is called a bruit. It does not necessarily mean there is an abnormality, just that it is detected. (Similar to hearing water going through a pipe — you hear it — and just because you hear it does not mean it is abnormal.) The term “murmur” should not be confused with the term “abnormal murmur” just as the word “temperature” should not be confused with the term “fever.” However, people often mistakenly use both terms interchangeably.
The infographic and information below explain heart mumurs.
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Murmurs are not always significant; they may be normal or innocent. Innocent murmurs are usually found incidentally during a physical exam. They require no further evaluation. Pathologic murmurs are due to abnormal blood flow, usually as a result of a cardiac abnormality. These ought to be referred to a pediatric cardiologist (even prior to testing to avoid duplication and the improper performance of tests).
The classification of heart murmurs is based on their loudness, where in the heart pumping cycle they occur, and where on the chest they are best heard. From these characteristics, the likely cause of a murmur can be predicted.
Each pump of the heart is a two-phase process:
- Systole is the name for the pumping phase
- Diastole is the name for the resting, filling phase
A murmur heard during systole is systolic; likewise, a murmur heard during diastole is diastolic.
The intensity and timing of a murmur, particularly when accompanied by symptoms, may suggest that the murmur is significant. Such a murmur needs to be evaluated to determine the underlying structural problem. Many heart abnormalities can be corrected before the heart muscle is permanently damaged.
The sound is the result of noisy or turbulent blood flow in the heart. This turbulence may be a normal amount, but louder due to the acoustics which vary from patient to patient (just like concert halls vary in their acoustics). The turbulence may also be abnormal due to abnormal areas of blood flow from abnormalities in the heart. Abnormal heart murmurs can be caused by congenital abnormalities (that is, abnormalities present at birth). Abnormal murmurs can also result from heart infections. These murmurs are usually due to valve leakiness or thickening. Some abnormal murmurs arise from heart muscle damage resulting from coronary artery disease, hypertension or a cardiomyopathy.
The symptoms of a significant heart murmur depend on the heart abnormality and its severity. Possible symptoms include:
- Shortness of breath
- Inability to tolerate exertion or poor feeding and weight gain in infants
- Frequent episodes of rapid heart rate
- Chest pain
Technology has made great progress beyond the simple stethoscope in the diagnosis of heart murmurs. For example:
- An electrocardiogram can detect any associated electrical abnormalities
- A chest x-ray screens for an enlarged heart, signs of heart muscle failure and certain congenital abnormalities
- An echocardiogram uses sound waves to create images of the heart structure. The images may show a hole in the wall of the heart or an abnormal valve.
- In some cases, cardiac catheterization may be necessary to determine the structural problem. This technique also allows measurement of the pressures in the heart chambers and of valve function.
Not all abnormal murmurs require treatment. The decision for treatment depends on several factors:
- The symptoms
- The risk of heart damage over time if the abnormality is not corrected
- The risk of sudden complications, such as stroke or cardiac arrest
The treatment for correcting significant heart murmur may be an interventional procedure in the cardiac catheterization laboratory, or a surgical operation.
Most abnormal murmurs should be followed by a pediatric cardiologist familiar with the cardiac abnormality causing the murmur and the long-term management of it.
The specialists in Lurie Children's Heart Center treat heart murmurs. Learn more.