Types of Congenital Heart Defects

Congenital heart defects change the normal flow of blood through the heart. This is because some part of the heart didn't develop properly before birth.

There are many types of congenital heart defects. Some are simple, such as a hole in the septum that allows blood from the left and right sides of the heart to mix, or a narrowed valve that blocks blood flow 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 problems with how the heart develops.

Examples of 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. The wall prevents mixing of blood between the two sides of the heart. Sometimes, a baby is born with a hole in the septum. The hole allows blood to mix between the two sides of the heart.

Atrial septal defect (ASD). An 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.

Normal Heart and Heart With Atrial Septal Defect

Figure A shows the structure and blood flow in the interior of a normal heart. Figure B shows a heart with an atrial septal defect, which allows oxygen-rich blood from the left atrium to mix with oxygen-poor blood from the right atrium.

An ASD can be small or large. Small ASDs allow only a little blood to leak from one atrium to the other. Very small ASDs don't affect the way the heart works and don't require any treatment. Many small ASDs close on their own as the heart grows during childhood.

Medium to large ASDs allow more blood to leak from one atrium to the other, and they're less likely to close on their own.

Half of all ASDs close on their own or are so small that no treatment is needed. Medium to large ASDs that need treatment can be repaired using a catheter procedure or open-heart surgery.

Ventricular septal defect (VSD). A 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.

Normal Heart and Heart With Ventricular Septal Defect

Figure A shows the structure and blood flow in the interior of a normal heart. Figure B shows two common locations for a ventricular septal defect. The defect allows oxygen-rich blood from the left ventricle to mix with oxygen-poor blood in the right ventricle.

A VSD can be small or large. A small VSD doesn't cause problems and may close on its own. Large VSDs cause the left side of the heart to work too hard. This increases blood pressure in the right side of the heart and the lungs because of the extra blood flow.

The increased work of the heart can cause heart failure and poor growth. If the hole isn't closed, high blood pressure can scar the delicate arteries in the lungs. Open-heart surgery is used to repair VSDs.

Narrowed Valves

Simple congenital heart defects also can involve the heart's valves. These valves 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 (ste-NO-sis). This defect occurs if the flaps of a valve thicken, stiffen, or fuse together. This prevents the valve from fully opening. The heart has to work harder to pump blood through the valve.
• Atresia (a-TRE-ze-AH). This defect occurs if a valve doesn't form correctly and lacks a hole for blood to pass through. Atresia of a valve generally results in more complex congenital heart disease.
• Regurgitation (re-GUR-ji-TA-shun). 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 artery. From there it flows to the lungs to pick up oxygen.

Pulmonary valve stenosis can range from mild to severe. Most children who have this defect have no signs or symptoms other than a heart murmur. (A heart murmur is an extra or unusual sound heard during a heartbeat.) Treatment isn't needed if the stenosis is mild.

In babies who have severe pulmonary valve stenosis, the right ventricle can get very overworked trying to pump blood to the pulmonary artery. These infants may have symptoms such as rapid or heavy breathing, fatigue (tiredness), or poor feeding.

If a baby also has an ASD or patent ductus arteriosus (PDA), oxygen-poor blood can flow from the right side of the heart to the left side. This can cause cyanosis (si-a-NO-sis). 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 who have severe pulmonary valve stenosis may have symptoms such as fatigue while exercising. Severe pulmonary valve stenosis is treated with a catheter procedure.

Example of a Complex Congenital Heart Defect

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 (teh-TRAL-o-je of fah-LO), a combination of four defects:

• Pulmonary valve stenosis.
• A large VSD.
• An overriding aorta. In this defect, 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. In this defect, the muscle of the right ventricle is thicker than usual because of having to work harder than normal.

Together, these four defects mean that not enough blood is able to reach the lungs to get oxygen, and oxygen-poor blood flows out to the body.

Normal Heart and Heart With Tetralogy of Fallot

Figure A shows the structure and blood flow in the interior of a normal heart. Figure B shows a heart with the four defects of tetralogy of Fallot.

Babies and children who have tetralogy of Fallot have episodes of cyanosis, which can sometimes be severe. In the past, when this condition wasn't treated in infancy, older children would get very tired during exercise and could have fainting spells. Tetralogy of Fallot is now repaired in infancy to prevent these types of symptoms.

Tetralogy of Fallot must be repaired with open-heart surgery, either soon after birth or later in infancy. The timing of the surgery will depend on how much the pulmonary artery is narrowed.

Children who have had this heart defect repaired need lifelong medical care from a specialist to make sure they stay as healthy as possible.