What is a heart murmur?

A heart murmur is an extra or abnormal sound produced by the heart and heard with the stethoscope.

How does it occur?

In most cases the abnormal sound is the result of noisy or turbulent blood flow in the heart. The turbulence may be caused by the shape of the heart or by abnormalities of specific heart structures, such as the valves or the heart walls.

Heart murmurs can be caused by congenital abnormalities (that is, abnormalities present at birth). Murmurs can result from heart infections when a person has rheumatic fever from streptococcal infections, such as strep throat; however, this occurs less often now than in the past. Some murmurs do arise from heart muscle damage resulting from coronary artery disease or hypertension.

How are murmurs classified?

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.

Loudness is on a scale of I (faint) to VI (loud enough to be heard even if the stethoscope is not touching the chest).

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.

Murmurs are not always significant. A murmur is called functional or benign if no symptoms are associated with it and its sound and location do not indicate a heart problem. Such murmurs are usually found incidentally during a physical exam. They require no further evaluation.

The intensity and timing of a murmur, and sometimes associated 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.

What are the symptoms?

The symptoms of a significant heart murmur depend on the heart abnormality and its severity. Possible symptoms include:

• shortness of breath

• lightheadedness

• inability to tolerate exertion

• frequent episodes of rapid heart rate

• chest pain.

How is it diagnosed?

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.

How is it treated?

Some murmurs do not 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 a defect causing a heart murmur is open heart surgery.

What can be done to help prevent heart murmurs?

Little is known about how to prevent heart murmurs present at birth. However, the conditions of coronary artery disease or hypertension, which can cause heart muscle damage, can sometimes be prevented, delayed, or minimized by healthy diet and exercise habits, and by not smoking.

Always get prompt treatment for strep infections to prevent rheumatic heart disease.