Causes

Researchers aren't sure what causes most types of congenital heart disease. Some congenital heart diseases are passed down through families (inherited).

To understand congenital heart disease, it helps to know how the heart works.

• The heart is divided into chambers — two upper chambers (atria) and two lower chambers (ventricles).
• The right side of the heart moves blood to the lungs through blood vessels (pulmonary arteries).
• In the lungs, blood picks up oxygen and then returns to the left side of your heart through the pulmonary veins.
• The left side of the heart then pumps the blood through the aorta and out to the rest of the body.

Congenital heart disease can affect any of these heart structures, including the arteries, valves, chambers and the wall of tissue that separates the chambers (septum).