A defect of the heart or major blood vessels is present at birth in about seven of every 1,000 live births. Any part of the cardiovascular system can be affected, and more than one defect can occur in the same person. Some defects are mild enough to go unnoticed at birth, while others can cause major problems shortly after the baby is born.
No one knows exactly what causes congenital heart defects. Abnormalities in chromosomes including the one that causes Down syndrome are associated with some heart defects. Infections such as German measles (rubella) in the mother during early pregnancy and medications taken during pregnancy also increase the risk. If there's a family history of congenital heart disease, genetic counseling should be considered before pregnancy. Sometimes the cause can't be identified.
Common congenital heart defects include:
- Abnormally formed blood vessels that impede the flow of blood;
- Valves that obstruct blood flow, allow backward leakage or are missing;
- Incorrect or reversed connections between the main arteries and the heart or between the main veins and the heart;
- Defects in the partition between the atria or the ventricles that allows blood to flow from the right side to the left side of the heart without going through the lungs, or from the left side to the right side without going through the rest of the body.