heart murmur

heart murmur, condition characterized by prolonged noises made by blood circulating through the heart. A heart murmur is often described as a swishing or hissing sound that occurs after the normal heartbeat sound and is audible through a stethoscope. Heart murmurs are classified into two types: innocent, which are harmless, and abnormal, which are pathological. Such noises may also be the result of vibrations caused by heart valve deformity. Some people are born with heart murmurs, called congenital murmurs. Others develop them at some point in their lives; these are called acquired murmurs.

Types

Innocent murmurs are harmless and are caused by the sound of blood circulating normally through the chambers and valves of the heart. Innocent murmurs can be caused by several factors, including physical overexertion, fever, hyperthyroidism, anemia, pregnancy, and, in children, phases of rapid physical growth. If a physician hears a heart murmur through a stethoscope, they may conduct diagnostic tests, such as an electrocardiogram (ECG or EKG) or echocardiogram (a test that uses ultrasound to examine the heart’s structure and functions), to determine whether a heart murmur is an innocent one. If this is the case, the patient will not require any restrictions on activities or medications. Many people have innocent heart murmurs during childhood, and, for most, these murmurs disappear as they reach adulthood. However, for some they are a lifelong condition.

Abnormal heart murmurs are pathological and are caused by either the partial obstruction of heart valves or the leakage of blood through them, causing turbulent blood flow through the heart. In adults, abnormal heart murmurs can be acquired as a result of age, the buildup of calcium, or diseases that can affect the heart. For example, age can cause heart valves to stiffen or harden. Calcium deposits can also stiffen heart valves, allowing blood to flow backward through the heart. This condition is called calcific aortic valve disease. Endocarditis, an inflammation of the heart lining that can damage heart valves, is caused by bacteria and other microorganisms. Rheumatic fever, a complication of strep throat, can also affect heart valves. Abnormal heart murmurs in children are usually congenital. They are caused by holes in the heart or cardiac shunts, which are structural issues that cause blood to flow irregularly through the atria or ventricles of the heart or through nearby blood vessels.

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Symptoms and risks

Symptoms of abnormal heart murmurs include chest pain; shortness of breath; blue or gray skin; fatigue; swollen liver, neck veins, or ankles; swelling or sudden weight gain; fainting (syncope); persistent cough; heavy sweating; and, in infants, poor appetite and lack of growth. Abnormal heart murmurs occur with many different heart conditions, and the particular sounds that a murmur makes can sometimes reveal the location of the issue in the heart. Medical treatment may be necessary if a heart condition is causing an abnormal murmur.

Risk factors that may cause heart murmurs in infants include the use of alcohol, drugs, narcotics or certain medications during pregnancy and uncontrolled diabetes or rubella (German measles) during pregnancy. In adults, certain medical conditions are risk factors for heart murmurs, such as anemia; hyperthyroidism; pulmonary hypertension; certain autoimmune disorders, such as lupus and rheumatoid arthritis; and cardiomyopathy.