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born with a congenital heart defect—about 35,000 babies each year. Defects range in severity from simple problems—holes between heart chambers, abnormal valves or connections of heart vessels, abnormally narrow heart vessels—to very severe malformations, such as the complete absence of one or more chambers or valves.

Defects appear when a mishap occurs during heart development soon after conception—often before the mother realizes she is pregnant. These defects are usually but not always diagnosed early in life.

Severe heart disease generally becomes evident during the first few months after birth. Some problems trigger very low blood pressure shortly after birth; others cause breathing difficulties, feeding problems, or poor weight gain. Minor defects are most often diagnosed on a routine medical checkup, since these defects rarely cause symptoms. While most heart murmurs in children are normal, some may be due to defects.

Cause The cause of congenital heart problems is often unknown. Although the reason most defects occur is presumed to be genetic, only a few genes have been discovered that have been linked to the presence of heart defects. Rarely the ingestion of some drugs and the occurrence of some infections during pregnancy can cause defects. A maternal viral infection may also produce serious problems. For example, if a pregnant mother gets german measles (rubella), the infection may interfere with the baby's heart as it develops or may lead to other malformations. other viral diseases also may cause defects before birth. Certain conditions that affect multiple organs, such as down syndrome, also can involve the heart.

Acquired Heart Disease

Acquired heart disease develops at some point during childhood as a result of infection—a much more unusual type of heart disease. This includes conditions such as kawasaki disease, rheumatic fever, and infective endocarditis. Children also can develop heart rate problems such as slow, fast, or irregular heart beats, known as "arrhythmias."

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