Heart Murmur

HEART MURMUR

DEFINITION

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A heart murmur is an abnormal extra sound made when the heart beats. The sound is produced by blood moving through the heart and its valves.

DESCRIPTION

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Heart Murmur: Words to Know

Atrium (plural: atria):

One of the two upper chambers of the heart.

Echocardiogram:

A test that uses sound waves to produce an image of the inside of the heart.

Electrocardiogram:

A test that measures the electrical activity of the heart to determine whether it is functioning normally.

Ventricle:

One of the two lower chambers of the heart.

Blood flows from the body into the heart through veins. It moves from one side of the heart (the atria) into the other side of the heart (the ventricles). It then flows out of the heart through arteries. The flow of blood is controlled by muscular flaps called valves. The valves open and close as blood flows through each part of the heart. When the valves between the atria and the ventricles close, they make a "lubb" sound. When the valves between the ventricles and the major arteries close, they make a "dubb" sound. When doctors listen to the heart beat of a healthy person, they hear a "lubb-dubb" sound.

A heart murmur is a sound other than the usual "lubb-dubb" sound produced by the heart. It usually lasts longer than a normal heart sound and can be heard between the normal "lubb-dubb" sounds.

Heart murmurs occur in normal hearts. They are especially common among young children. Harmless heart murmurs are known as innocent heart murmurs. Innocent heart murmurs are usually very faint. They come and go in an irregular pattern. They do not pose a health threat to the person in whom they occur.

Other heart murmurs are more dangerous. They are called pathological heart murmurs. One cause of pathological heart murmurs is a damaged heart valve. Pathological heart murmurs may be an indication of a serious heart problem. The sound they make is louder and more continuous than that of an innocent heart murmur. They are sometimes described as a clicking or galloping sound.

CAUSES

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Innocent heart murmurs are caused by the normal sound of blood flowing through the heart and its blood vessels. They may also be caused by emotions, such as stress or fear, or by health problems, such as fever or anemia (see anemia entry).

Pathological heart murmurs are usually caused by one of two problems. One of these problems is a defective heart valve. The valve may not close or open completely. When that happens, blood does not flow normally through the heart. Enough blood may not be able to get through the heart, or the blood may back up and go the wrong direction.

The other problem is a hole in the heart. A hole sometimes develops in the wall between the left and right sides of the heart. A hole of this kind may be relatively harmless, or it may cause heart problems that require surgery.

SYMPTOMS

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Innocent heart murmurs usually have no symptoms. They have no effect on the way the heart functions. Murmurs caused by defects in the heart do have symptoms. Those symptoms include shortness of breath, dizziness, chest pains, palpitations (a feeling that the heart is beating faster or less regular than normal), and congestion of the lungs.

DIAGNOSIS

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Heart murmurs can usually be detected quite easily. A doctor listens to a patient's chest with a stethoscope. Any sounds other than the normal "lubb-dubb" beating of the heart can be heard. If the sounds are faint, they may indicate an innocent heart murmur. An innocent heart murmur usually requires no further treatment.

One exception involves faint heart murmurs that occur in infants and children with other symptoms. Those symptoms in infants include poor appetite, problems with breathing normally, and failure to develop normally. In older children, symptoms include loss of consciousness or inability to take part in normal exercise.

The presence of a loud heart murmur may lead to further tests. A chest X ray, for example, may show the presence of defects in the heart. An electrocardiogram (ECG, pronounced ih-LEK-tro-KAR-dee-o-gram) shows whether the heart is beating normally. An electrocardiogram is a test in which the electrical activity of the heart is recorded.

An echocardiogram (pronounced ekko-KAR-dee-o-gram) may also be used to diagnose heart murmur. An echocardiogram is a test in which sound waves are sent through the heart. The path taken by the sound waves is recorded. The pattern of reflected sound may show any defects in the heart.

TREATMENT

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Innocent heart murmurs require no treatment. Pathological heart murmurs may also require no treatment unless they are serious. In that case, surgery may be required to correct the heart defect such as defective valves or holes in the heart.

PROGNOSIS

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Most children with innocent heart murmurs outgrow them by the time they reach adulthood. Severe cases of pathological heart murmurs may require surgery. If surgery is not successful, murmurs may develop into more serious heart problems that, in relatively rare cases, may lead to death.

PREVENTION

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There is no known method for preventing heart murmurs.

FOR MORE INFORMATION

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Organizations

American Heart Association. National Center. 7272 Greenville Ave., Dallas, TX 75231-4596. (214) 373–6300. http://www.medsearch.com/pf/profiles/amerh.

Web sites

"Heart Murmurs in Infants: Not Always Cause for Alarm." Mayo Health Oasis. (February 26, 1998) [Online] http://www.mayohealth.org (accessed on March 4, 1998).

"When Your Child's Doctor Hears a Heart Murmur." Children's National Medical Center 1998. [Online] http://www.cnmc.org/heart.htm (accessed on March 6, 1998).