Congenital Heart Disease (cont.)
What are the types of congenital heart defects?
Congenital heart defects change the normal flow of blood through the heart because some part of the heart didn't develop properly before birth.
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.
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. 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).
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 normal structure and blood flow in the interior of the 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 therefore don't need any special 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 usually be
repaired using a catheter procedure. (See
"How Are Congenital Heart Defects Treated?")
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 normal structure and blood flow in the interior of the 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 often close on its own. Large VSDs cause the left side of the heart to work too hard and increase 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, the high blood pressure in the lungs can cause the delicate arteries in the lungs to scar, a condition called pulmonary arterial hypertension. Open-heart surgery is used to repair VSDs.
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 (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 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.
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-TRALL-o-gee of fall-O), 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.
Normal Heart and Heart With Tetralogy of Fallot
Figure A shows the normal structure and blood flow in the interior of the heart. Figure B shows a heart with the four defects of tetralogy of Fallot.
Babies and children with 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, depending on how severely 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.
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