With congenital heart defects, some part of the heart doesn’t form properly before birth. This changes the normal flow of blood through the heart.
There are many types of congenital heart defects. Some are simple, such as a hole in the septum. The hole allows blood from the left and right sides of the heart to mix. Another example of a simple defect is a narrowed valve that blocks blood flow to the lungs or other parts of the body.
Other heart defects are more complex. They include combinations of simple defects, problems with the location of blood vessels leading to and from the heart, and more serious problems with how the heart develops.
The septum is the wall that separates the chambers on left and right sides of the heart. The wall prevents blood from mixing between the two sides of the heart. Some babies are born with holes in the septum. These holes allow 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. The hole allows oxygen-rich blood from the left atrium to flow into the right atrium, instead of flowing into the left ventricle as it should. Many children who have ASDs have few, if any, symptoms.
ASDs can be small, medium, or large. Small ASDs allow only a little blood to leak from one atrium to the other. They don't affect how the heart works and don't need any special treatment. Many small ASDs close on their own as the heart grows during childhood.
Medium and large ASDs allow more blood to leak from one atrium to the other. They’re less likely to close on their own.
About half of all ASDs close on their own over time. Medium and 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.
VSDs can be small, medium, or large. Small VSDs don't cause problems and may close on their own. Medium VSDs are less likely to close on their own and may require treatment.
Large VSDs allow a lot of blood to flow from the left ventricle to the right ventricle. As a result, the left side of the heart must work harder than normal. Extra blood flow increases blood pressure in the right side of the heart and the lungs.
The heart’s extra workload can cause heart failure and poor growth. If the hole isn't closed, high blood pressure can scar the arteries in the lungs.
Doctors use open-heart surgery to repair VSDs.
Patent ductus arteriosus (PDA) is a fairly common heart defect that can occur soon after birth. In PDA, abnormal blood flow occurs between the aorta and the pulmonary artery.
Before birth, these arteries are connected by a blood vessel called the ductus arteriosus. This blood vessel is an essential part of fetal blood circulation. Within minutes or up to a few days after birth, the ductus arteriosus closes.
In some babies, however, the ductus arteriosus remains open (patent). The opening allows oxygen-rich blood from the aorta to mix with oxygen-poor blood from the pulmonary artery. This can strain the heart and increase blood pressure in the lung arteries.
A heart murmur might be the only sign of PDA. (A heart murmur is an extra or unusual sound heard during a heartbeat.) Other signs and symptoms can include shortness of breath, poor feeding and growth, tiring easily, and sweating with exertion.
PDA is treated with medicines, catheter-based procedures, and surgery. Small PDAs often close without treatment.
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:
The most common valve defect is 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. The blood then travels 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. 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 signs and symptoms such as rapid or heavy breathing, fatigue (tiredness), and poor feeding. Older children who have severe pulmonary valve stenosis may have symptoms such as fatigue while exercising.
Some babies may have pulmonary valve stenosis and PDA or ASDs. If this happens, oxygen-poor blood can flow from the right side of the heart to the left side. This can cause cyanosis (si-ah-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.
Severe pulmonary valve stenosis is treated with a catheter procedure.
Complex congenital heart defects need to be repaired with surgery. Advances in treatment now allow doctors to 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), which is a combination of four defects:
In tetralogy of Fallot, not enough blood is able to reach the lungs to get oxygen, and oxygen-poor blood flows to the body.
Babies and children who have tetralogy of Fallot have episodes of cyanosis, which can be severe. In the past, when this condition wasn't treated in infancy, older children would get very tired during exercise and might faint. Tetralogy of Fallot is repaired in infancy now to prevent these problems.
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 narrow the pulmonary artery is.
Children who have had this heart defect repaired need lifelong medical care from a specialist to make sure they stay as healthy as possible.
Researchers take step in unlocking the causes of congenital heart disease
Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Congenital Heart Defects, visit www.clinicaltrials.gov.
Visit Children and Clinical Studies to hear experts, parents, and children talk about their experiences with clinical research.
May 12, 2013
NIH Media Availability: Researchers take important step in unlocking what causes congenital heart disease
Findings from the first large-scale sequencing analysis of congenital heart disease bring us closer to understanding this most common type of birth defect.
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