There are many types of congenital heart defects. They include simple ones such as a hole in the interior walls of the heart that allows blood from the left and right sides of the heart to mix, or a narrowed valve that blocks the flow of blood to the lungs or other parts of the body.

Other defects are more complex. These include combinations of simple defects, problems with where the blood vessels leading to and from the heart are located, and more serious abnormalities in how the heart develops.

Simple Congenital Heart Defects

Holes in the Heart (Septal Defects)

The septum is the wall that separates the chambers on the left side of the heart from those on the right. It prevents mixing of blood between the two sides of the heart. Sometimes, a baby is born with a hole in the septum. When that occurs, blood can mix between the two sides of the heart.

Atrial septal defect (ASD) is a hole in the part of the septum that separates the atria—the upper chambers of the heart. This heart defect allows oxygen-rich blood from the left atrium to flow into the right atrium instead of flowing to the left ventricle as it should. Many children who have ASDs have few, if any, symptoms.

Ventricular septal defect (VSD) is a hole in the part of the septum that separates the ventricles—the lower chambers of the heart. The hole allows oxygen rich blood to flow from the left ventricle into the right ventricle instead of flowing into the aorta and out to the body as it should.

Narrowed Valves

Simple congenital heart defects also can involve the heart’s valves, which control the flow of blood from the atria to the ventricles and from the ventricles into the two large arteries connected to the heart (the aorta and the pulmonary artery). Valves can have the following types of defects:

• Stenosis. This is when the valve doesn’t open completely, and the heart has to work harder to pump the blood through the valve.
• Atresia. This is when the valve doesn’t form correctly, so there is no opening for blood to pass through.
• Regurgitation. This is when the valve doesn’t close completely, so blood leaks back through the valve.

The most common valve defect is called pulmonary valve stenosis, which is a narrowing of the pulmonary valve. This valve allows blood to flow from the right ventricle into the pulmonary arteries and out to the lungs to pick up oxygen.

Pulmonary valve stenosis can range from mild to severe. Most children with this defect have no signs or symptoms other than a heart murmur. Treatment isn’t needed if the stenosis is mild.

In a baby with severe pulmonary valve stenosis, the right ventricle can get very overworked trying to pump blood to the pulmonary arteries. Oxygen-poor blood can back up from the right side of the heart into the left side, causing cyanosis. Cyanosis is a bluish tint to the skin, lips, and fingernails. It occurs because the oxygen level in the blood leaving the heart is below normal.

Older children with severe pulmonary valve stenosis may have symptoms such as fatigue (tiredness) when exercising. Severe pulmonary valve stenosis is treated with a catheter procedure.

Complex Congenital Heart Defects

Complex congenital heart defects need to be repaired with surgery. Because of advances in diagnosis and treatment, doctors can now successfully repair even very complex congenital heart defects.

The most common complex heart defect is tetralogy of Fallot, a combination of four defects:

• Pulmonary valve stenosis.
• A large VSD.
• An overriding aorta. The aorta sits above both the left and right ventricles over the VSD, rather than just over the left ventricle. As a result, oxygen poor blood from the right ventricle can flow directly into the aorta instead of into the pulmonary artery to the lungs.
• Right ventricular hypertrophy. The muscle of the right ventricle is thicker than usual because of having to work harder than normal.

These defects prevent enough blood from flowing to the lungs to get oxygen, while oxygen-poor blood flows directly out to the body.

• 0