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Congenital Heart Defects

A congenital heart defect (CHD) is when the heart or the blood vessels near the heart don’t develop normally before birth.

CHDs occur in about 1 out of 100 babies. Most young people with these conditions are living into adulthood now. This is due to advances in testing, treatment, and surgeries.

In most cases, the cause of a congenital heart defect is unknown. Sometimes a viral infection in the mother causes the condition. The condition can be passed on through the parents’ genes (genetic or hereditary). Some congenital heart defects are due to alcohol or drug use during pregnancy.

Most heart defects either cause an abnormal blood flow through the heart, or block blood flow in the heart or vessels. (A blockage is called stenosis and can occur in heart valves, arteries, or veins.) A hole between 2 chambers of the heart is an example of a very common type of congenital heart defect.

More rare defects include those in which:

  • The right or left side of the heart is not fully formed (hypoplastic)
  • There is only 1 ventricle
  • Both the pulmonary artery and aorta start from the same ventricle
  • The pulmonary artery and aorta start from the wrong ventricles

For more information on this topic, visit our Health Library.