What is an Atrial Septal Defect?
An atrial septal defect (ASD) — sometimes referred to as a hole in the heart — is a type of congenital heart defect in which there is an abnormal opening in the dividing wall between the upper filling chambers of the heart (the atria). In most cases ASDs are diagnosed and treated successfully with few or no complications.
To understand this defect, it first helps to review some basics about the way a healthy heart typically works.
The heart has four chambers: The two lower pumping chambers are called the ventricles, and the two upper filling chambers are the atria.
In a healthy heart, blood that returns from the body to the right-sided filling chamber (right atrium) is low in oxygen. This blood passes to the right-sided pumping chamber (right ventricle), and then to the lungs to receive oxygen. The blood that has been enriched with oxygen returns to the left atrium, and then to the left ventricle. It's then pumped out to the body through the aorta, a large blood vessel that carries the blood to the smaller blood vessels in the body. The right and left filling chambers are separated by a thin shared wall, called the atrial septum.
Kids with an atrial septal defect (ASD) have an opening in the wall (septum) between the atria. As a result, some oxygenated blood from the left atrium flows through the hole in the septum into the right atrium, where it mixes with oxygen-poor blood and increases the total amount of blood that flows toward the lungs. The increased blood flow to the lungs creates creates a swishing sound, known as a heart murmur. This heart murmur, along with other specific heart sounds that can be detected by a cardiologist, may be clues that a child has an ASD.
ASDs can be located in different places on the atrial septum, and they can be different sizes. The symptoms and medical treatment of the defect will depend on those factors. In some rare cases, ASDs are part of more complex types of congenital heart disease. It's not clear why, but ASDs are more common in girls than in boys.
Causes
ASDs occur during fetal development of the heart and are present at birth. During the first weeks after conception, the heart develops. If a problem occurs during this process, a hole in the atrial septum may result.
In some cases, the tendency to develop a ASD may be genetic. There can be genetic syndromes that cause extra or missing pieces of chromosomes that can be associated with ASD. For the vast majority of children with a defect, however, there's no clear cause of the ASD.
Signs and Symptoms
The size of an ASD and its location in the heart will determine what kinds of symptoms a child experiences. Most children who have ASDs seem healthy and appear to have no symptoms. Generally, kids with an ASD feel well and grow and gain weight normally. Infants and children with larger, more severe ASDs, however, may possibly show some of the following signs or symptoms:
- poor appetite
- poor growth
- fatigue
- shortness of breath
- lung problems and infections, such as pneumonia
If an ASD is not treated, health problems can develop later, including an abnormal heart rhythm (known as an atrial arrhythmia) and problems in how well the heart pumps blood. As kids with ASDs get older, they may also be at an increased risk for stroke, since a blood clot that develops can pass through the hole in the wall between the atria and travel to the brain. Pulmonary hypertension (high blood pressure in the lungs) may also develop over time in older patients with larger untreated ASDs.
Fortunately, most kids with ASD are diagnosed and treated long before the heart defect causes physical symptoms. Because of the complications that ASDs can cause later in life, pediatric cardiologists often recommend closing ASDs early in childhood.
Diagnosis
Generally, a child's doctor hears the heart murmur caused by ASD during a routine checkup or physical examination. ASDs are not always diagnosed as early in life as other types of heart problems, such as ventricular septal defect (a hole in the wall between the two ventricles). The murmur caused by an ASD is not as loud and may be more difficult to hear than other types of heart murmurs, so it may be diagnosed any time between infancy and adolescence (or even as late as adulthood).
If a doctor hears a murmur and suspects a heart defect, the child may be referred to a pediatric cardiologist, a doctor who specializes in diagnosing and treating childhood heart conditions. If an ASD is suspected, the cardiologist may order one or more of the following tests:
- chest X-ray, which produces an image of the heart and surrounding organs
- electrocardiogram (EKG), which records the electrical activity of the heart and can indicate volume overload of the right side of the heart
- echocardiogram (echo), which uses sound waves to produce a picture of the heart and to visualize blood flow through the heart chambers. This is often the primary tool used to diagnose ASD.
Treatment
Once an ASD is diagnosed, treatment will depend on the child's age and the size, location, and severity of the defect. In kids with very small ASDs, the defect may close on its own. Larger ASDs usually won't close, and must be treated medically. Most of these can be closed in a cardiac catheterization lab, although some ASDs will require open-heart surgery.
A child with a small defect that causes no symptoms may simply need to visit a pediatric cardiologist regularly to ensure that there are no problems; often, small defects will close spontaneously without any treatment during the first years of life. In general, a child with a small ASD won't require restrictions on his or her physical activity.
In most children with ASD, though, doctors must close the defect if it has not closed on its own by the time a child is old enough to start school.
Depending on the position of the defect, many children with ASD can have it corrected with a cardiac catheterization. In this procedure, a thin, flexible tube called a catheter is inserted into a blood vessel in the leg that leads to the heart. A cardiologist guides the tube into the heart to make measurements of blood flow, pressure, and oxygen levels in the heart chambers. A special implant can be positioned into the hole in the septum. The device is designed to flatten against the septum on both sides to close and permanently seal the ASD. In the beginning, the natural pressure in the heart holds the device in place. Over time, the normal tissue of the heart grows over the device and covers it entirely. This non-surgical technique for closing an ASD eliminates the scar on the chest needed for the surgical approach, and has a shorter recovery time, usually just an overnight stay in the hospital.
Because there is a small risk of blood clots forming on the closure device while new tissue heals over it, children who undergo device closure of an ASD may need to be on medications for several months after the procedure to prevent clots from forming.
If surgical repair for ASD is necessary, a child will undergo open-heart surgery. In this procedure, a surgeon makes a cut in the chest and a heart-lung machine is used to do the work of the circulation while the heart surgeon closes the hole. The ASD may be closed directly with stitches or by sewing a patch of surgical material over the defect. Eventually, the tissue of the heart heals over the patch or stitches, and by 6 months after the surgery, the hole will be completely covered with tissue.
For 6 months following catheterization or surgical closure of an ASD, antibiotics are recommended before routine dental work or surgical procedures to prevent infective endocarditis. Once the tissue of the heart has healed over the closed ASD most people who have had their ASDs corrected no longer need to worry about having a higher risk of infective endocarditis.
Your doctor will discuss other possible risks and complications with you prior to the procedure. Typically, after repair and adequate time for healing, children with ASD rarely experience further symptoms or disease.
Caring for Your Child
Kids who undergo cardiac catheterization to close an ASD usually spend the night in the hospital after the procedure. Those who have had a catheterization procedure should also be kept out of gym class or sports practice for a week; after a week, they can usually return to their normal physical activities, with their doctor's OK.
Kids who undergo surgery for their ASDs usually go home after a few days in the hospital if there are no complications. After surgical ASD repair, the main medical concern is the healing of the chest incision. In general, the younger patients are when they have their surgical repairs, the less pain they will have during recovery. The child will be watched closely for signs or symptoms that may indicate a problem. If your child has trouble breathing, is not eating, has fever, or redness or pus oozing from the incision, get medical treatment right away. In most cases, kids who have had ASD surgery recover quickly and without problems.
In the weeks following surgery or cardiac catheterization, your doctor will check on your child's progress. Your child may undergo another echocardiogram to make sure that the heart defect has closed completely. Kids who have undergone ASD repair will continue to have follow-up visits with the cardiologist.
Most children who undergo treatment for ASDs recover quickly — you may even notice that within a few weeks of treatment, your child is eating more and is more active than before surgery. However, some signs and symptoms may indicate a problem. If your child is having trouble breathing, call the doctor or take your child to the emergency department immediately. Other symptoms that may indicate a problem include:
- a bluish tinge or color (cyanosis) to the skin around the mouth or on the lips and tongue
- poor appetite or difficulty feeding
- failure to gain weight or weight loss
- listlessness or decreased activity level
- prolonged or unexplained fever
- increasing pain, tenderness, or pus oozing from the incision
Call your doctor if you notice any of these signs in your child after closure of the ASD.
Any time a child is diagnosed with a heart condition, it can be scary. But the good news is that your pediatric cardiologist will be very familiar with this condition and how to best manage it. Most kids who've had an ASD corrected have a normal life expectancy and go on to live healthy, active lives.
Reviewed by: Steven B. Ritz MD
Date reviewed: August 2007
