An atrial septal defect (ASD) is a type of congenital heart disease in which there is a hole in the wall (septum) of the heart between the right atrium and the left atrium.
Basic Facts
A hole in the wall between the right and left atria is called an atrial septal defect. Atrial septal defects, also referred to as ASDs, are common. They may be diagnosed in childhood or adulthood. The impact of the ASD on the heart depends on the size of the hole and whether there are other congenital heart abnormalities.
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Who Gets an ASD?
Anyone can be born with an ASD, but they run in some families. There are also rare syndromes that may be associated with ASD. ASD may also be one part of more complex congenital heart disease.
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What Happens Because of an ASD?
An ASD allows blood coming back to the left atrium to go into the right atrium. (The reason blood flows from left to right instead of right to left through an ASD is because the pressures in the left side of the heart are usually higher than the pressures on the right). This means that there is extra blood in the right atrium that will end up in the right ventricle. The right ventricle has to work harder to pump the extra blood. Eventually the right atrium and right ventricle become enlarged to deal with the extra blood.
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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.
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For an explanation of how a normal heart is structured and functions, please read the article on congenital heart disease.
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What Symptoms Does an ASD Cause?
An ASD may cause no symptoms at all. Infants and children rarely have symptoms due to an ASD. In those infants with large ASDs, they may not grow normally or may have heart failure. Heart failure in babies usually causes problems when the baby eats or cries. They may breathe rapidly, grunt or sweat when eating or crying.
Adolescents or adults with symptoms often have fatigue and shortness of breath, especially with exercise. Some have chest pain and some have swelling in their legs. Some patients will have abnormal heart rhythms (arrhythmias) that cause symptoms. Rarely an ASD can allow blood clots from the veins in the body to pass into the left side of the heart, causing a stroke, heart attack or other clot related problem. Clots going from the right side of the heart to the left side are called paradoxic emboli. This is uncommon, but for some people with excessive clotting, the ASD may need to be fixed to prevent paradoxic emboli.
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How Is an ASD Diagnosed?
Most often, an ASD is diagnosed because a doctor hears a heart murmur and gets an echocardiogram (heart ultrasound). The heart murmur is often faint, and is difficult to diagnose by just listening.
The echocardiogram can show the hole, as well as any abnormalities of the right heart caused by the hole. Sometimes, doctors get the echocardiogram because of symptoms. Other times tests done for other reasons might be abnormal, like a chest x-ray or electrocardiogram (ECG). The abnormality leads the doctors to suspect a heart condition, so they order an echocardiogram. Other tests, like CT scans, cardiac MRIs and cardiac catheterizations may also be used to diagnose an ASD.
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How is an ASD Treated?
An ASD may be so small that it doesn’t need treatment.
Medium and larger ASDs usually need to be fixed. The treatment is closure of the hole, which can be done with open heart surgery. In some cases, the ASD can be closed with a device placed through a catheter that is moved to the heart through a vein in the groin or neck.
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What are the Long-Term Problems with an ASD?
A small ASD may cause no heart problems. If an ASD is larger and isn’t fixed, it can eventually cause abnormal heart rhythms, failure of the right side of the heart or high pressures in the lungs. Some of these symptoms can be managed with medications if fixing the ASD isn’t an option.
Once an ASD is fixed, the right side of the heart will often return to normal size and any symptoms will get better. Sometimes the right heart doesn’t return to normal or there are still symptoms. Those patients need regular lifelong care from a cardiologist specializing in congenital heart defects.
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