Formula Medical Group
Apple Valley, CA

James Krider, MD

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Heart murmur

A normally functioning heart makes a number of sounds besides the steady thumping that occurs with its regular contractions. When a doctor listens to the heart with a stethoscope, he or she hears and assesses all of these sounds. The valves that separate the heart's chambers, for example, make clearly identifiable sounds when they snap shut as blood flows through them. Likewise, the movement of blood from one heart chamber to another makes a distinctive sound. In general, any unusual sound or group of sounds the heart makes is referred to as a heart murmur.

Although the presence of a heart murmur suggests an underlying cardiac abnormality, many heart murmurs have no medical significance. In infants and small children, doctors frequently detect so-called innocent murmurs, which are audible because children's chest walls are extremely thin.

In other cases, a heart murmur may be a sign of a potentially serious condition such as a congenital heart defect or an infection in the heart's lining. Doctors can sometimes distinguish these heart murmurs from relatively harmless ones simply by listening closely with a stethoscope. Often, however, it is necessary to perform further tests to identify the underlying problem.

Causes of heart murmurs

These conditions are characterized by a deficiency in the amount of blood in the number of red blood cells. Severe anemia may cause a heart murmur in addition to fatigue, pallor, and other characteristic symptoms.

Congenital heart defects
Congenital heart defects are present at birth. They occur when the heart or blood vessels near the heart fail to develop normally during the earliest stages of gestation. The most serious defects are usually diagnosed at birth or during infancy. Sometimes the first indication is a murmur, particularly if the defect is in a septum, which is one of the muscular walls dividing the chambers on the left side of the heart from the chambers on the right.

This bacterial infection causes inflammation of the

Most murmurs are "innocent" and not medically significant.

lining of the heart, which can damage the valves and lead to a murmur. Anyone who has abnormal valves or a congenital heart defect is at greater risk of developing this disease. Endocarditis can be fatal if not treated promptly, but antibiotic therapy usually cures the infection. Among the other symptoms of endocarditis are chills, fever, and loss of appetite.

Heart failure
Heart failure develops when the heart is unable to pump enough blood to meet the body's demands, even at rest. Eventually, blood backs up into the lungs, causing congestion. Symptoms include shortness of breath, fatigue, and swelling. Heart failure may be a consequence of a heart attack, high blood pressure, or heart-muscle disease. It usually arises in the left ventricle, the heart's major pumping chamber. But certain lung disorders can cause a condition called cor pulmonale, which produces failure of the right ventricle. Either type of heart failure may result in a heart murmur.

Heart valve disease
Four sets of valves control the flow of blood between the heart's upper and lower chambers and into the major blood vessels connected to the heart. The normal movements of these valves create the thumping of the heart. A number of different illnesses may damage the valves. The primary symptom is usually breathlessness, followed by abnormal heart rhythms and congestive heart failure if the condition is left untreated. A murmur is often audible upon examination.

The mitral valve, which connects the upper and lower chambers on the left side of the heart, is most vulnerable to damage. Many people have a condition called mitral valve prolapse that is usually benign and produces no signs or symptoms other than a characteristic "click" murmur.

High blood pressure
Hypertension, or high blood pressure, also affects the heart valves unless it is controlled. Blood pressure should be measured regularly, since hypertension often has no symptoms. However, it can contribute to heart attacks and strokes. An abnormal heart sound is one of the earliest signs of hypertensive disease.

Rheumatic heart disease
In this condition, the heart valves are damaged by a disease process that begins with an infection, usually strep throat or scarlet fever. If not treated, the infection can develop into acute rheumatic fever. The first symptoms are a high fever lasting from 10 to 14 days, and arthritic pain and sore­ness that moves from one joint to another. Shortness of breath or chest pains indicate that the heart has been affected. Damage to the heart valves results in a murmur.

Advice about heart murmurs

  • Many heart murmurs are harmless. If the doctor hears a murmur, it is not necessarily a sign of serious illness, and no treatment may be required.
  • A murmur may indicate a damaged heart valve, and consultation with a cardiologist (heart specialist) could be in order to rule out different types of heart disease.
  • With modern diagnostic tools, it is possible today to discover a diseased or malfunctioning valve long before it causes any discomfort, and to take preventive action or monitoring to prevent future problems.
  • Faulty heart valves can be replaced with artificial ones. Most people who undergo valve-replacement surgery improve markedly.
This article was last reviewed October 24, 2005 by Dr. James Krider.
Reproduced in part with permission of Home Health Handbook.
Aortic valve disorder
Congenital heart defect
Heart failure, congestive
Heart failure, cor pulmonale
High blood pressure
Hypertension, secondary
Mitral valve disorder
Pulmonary valve disorder
Rheumatic heart disease
Tricuspid valve disorder

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