Atrial Septal Defect (ASD)

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Epidemiology

What is Atrial Septal Defect (ASD)?
Atrial septal defect (ASD) sometimes referred to as a hole in the heart is a congenital heart defect in which the wall that separates the upper heart chambers (atria) does not close completely. Congenital means the defect is present at birth.

The wall is called septum which separates the heart’s left and right sides. So when there is a large defect between the artia, a large amount of oxygen-rich (red) blood leaks from the heart’s left side back to the right side. Then this blood is pumped back to the lungs, despite already having been refreshed with oxygen. This is inefficient, because already-oxygenated blood displaces blood that needs oxygen. Many people with this defect have few, if any, symptoms.

A heart murmur is the increased blood flow to the lungs which creates creates a swishing sound. 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.

However, atrial septal defect 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.

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.

What are the causes of Atrial Septal Defect?
ASDs occur during faetal 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.

In fetal circulation, there is normally an opening between the two atria (the upper chambers of the heart) to allow blood to bypass the lungs. This opening usually closes around the time the baby is born.

If the ASD is persistent, blood continues to flow from the left to the right atria. This is called a shunt. If too much blood moves to the right side of the heart, pressures in the lungs build up. The shunt can be reversed so that blood flows from right to left. Many problems can occur if the shunt is large, but small atrial septal defects often cause very few problems and may be found much later in life.

ASD is not very common. When the person has no other congenital defect, symptoms may be absent, particularly in children. Symptoms may begin any time after birth through childhood. Individuals with ASD are at an increased risk for developing a number of complications including:

  • Atrial fibrillation (in adults)
  • Heart failure
  • Pulmonary overcirculation
  • Pulmonary hypertension
  • Stroke

What are the signs and symptoms for Atrial Septal Defect?
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, children 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

Small-to-moderate-sized defects may produce no symptoms, or not until middle age or later. Symptoms that may occur can include:

  • Difficulty breathing (dyspnea)
  • Frequent respiratory infections in children
  • Sensation of feeling the heart beat (palpitations) in adults
  • Shortness of breath with activity

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 infants and children 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. Due to the complications that ASDs can cause later in life, paediatric cardiologists often recommend closing ASDs early in childhood.

How is Atrial Septal Defect diagnosed?
Generally, a child’s doctor hears the heart murmur caused by ASD during a routine check-up 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 paediatric cardiologist, a doctor who specialises 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.

The doctor may hear abnormal heart sounds when listening to the chest with a stethoscope. A murmur may be heard only in certain body positions, and sometimes a murmur may not be heard at all. The physical exam may also reveal signs of heart failure in some adults.

If the shunt is large, increased blood flow across the tricuspid valve may create an additional murmur when the heart relaxes between beats.

Tests that may done include:

  • Echocardiography
  • Heart MRI
  • Transesophageal echocardiography (TEE)
  • Cardiac catheterization
  • Chest x-ray
  • Coronary angiography (for patients over 35 years old)
  • Doppler study of the heart
  • ECG

What are the treatments for Atrial Septal Defect?
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.

ASD may not require treatment if there are few or no symptoms, or if the defect is small. Surgical closure of the defect is recommended if the defect is large, the heart is swollen, or symptoms occur.

A procedure has been developed to close the defect without surgery. The procedure involves placing an ASD closure device into the heart through tubes called catheters. The health care provider makes a tiny surgical cut in the groin, then inserts the catheters into a blood vessel and up into the heart. The closure device is then placed across the ASD and the defect is closed.

Not all patients with atrial septal defects can have this procedure.

Prophylactic (preventive) antibiotics should be given prior to dental procedures to reduce the risk of developing infective endocarditis immediately after surgery for the ASD, but they are not required later on.

Surgical Therapy
Closing an atrial septal defect in childhood can prevent serious problems later in life. The long-term outlook is excellent. If atrial septal defects are diagnosed in adulthood, the defect is also repaired. Rarely, the defect is left unrepaired if there’s pulmonary hypertension (high blood pressure in the lungs). Your cardiologist can determine if the defect should be closed.

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.

What is the Ongoing Care for Atrial Septal Defect?
Regular Monitoring: After an ASD is closed, patients need follow-up with a cardiologist. Only rarely will they need to take medicine. Your cardiologist can monitor you with noninvasive tests if needed. These include electrocardiograms, Holter monitors, exercise stress tests and echocardiograms. They will help show if more procedures, such as a cardiac catheterization, are needed.

Medications:

Activity Restrictions: are almost never needed unless there are associated problems that you and your doctor have discussed.

Endocarditis Prevention: Not needed.

After undergoing surgery for ASDs, patients 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 patient will be watched closely for signs or symptoms that may indicate a problem. If the patient has trouble breathing, is not eating, has fever, or redness or pus oozing from the incision, get medical treatment right away. In most cases, patients who have had ASD surgery recover quickly and without problems

Children who undergo cardiac catheterisation to close an ASD usually spend the night in the hospital after the procedure. Those who have had a catheterisation 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.

In the weeks following surgery or cardiac catheterisation, 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. Children who have undergone ASD repair will continue to have follow-up visits with the cardiologist.

Most children who undergo treatment for ASDs recover quickly and 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 paediatric cardiologist will be very familiar with this condition and how to best manage it. Most children who’ve had an ASD corrected have a normal life expectancy and go on to live healthy, active lives.

What Problems can arise?
People with repaired atrial septal defects rarely have any problems. Those who have palpitations or faint need to be reevaluated by their cardiologist and may need medical therapy. Also, if the ASD is diagnosed late in life, the heart may be less able to pump. This can require diuretics, drugs to help the heart pump better and drugs to control blood pressure. If pulmonary hypertension develops (which is rare), some people may need more medications.

With a small-to-moderate atrial septal defect, a person may live a normal life span without symptoms. Larger defects may cause disability by middle age because of increased blood flow and shunting of blood back into the pulmonary circulation.

Possible complications

  • Arrhythmias, particularly atrial fibrillation
  • Heart failure
  • Pulmonary hypertension
  • Stroke

Will You Need More Surgery?
Once an ASD has been closed, it’s unlikely that more surgery will be needed. Rarely, a patient may have a residual hole. Whether it will need to be closed depends upon its size.

Prevention There is no known way to prevent the defect, but some of the complications can be prevented with early detection.

Related Links/Further Reading

http://www.cincinnatichildrens.org/health/heart-encyclopedia/anomalies/asd.htm
http://www.americanheart.org/presenter.jhtml?identifier=11065
http://kidshealth.org/parent/medical/heart/asd.html#en.wikipedia.org/wik/iAtrial_septal_defect
http://www.nlm.nih.gov/medlineplus/ency/article/000157.htm

Disclaimer: The facts and opinions shown in this article are as accurate and up to date as possible, but are provided as general “information resources”, which may not be relevant to individual persons. This article is not a substitute for individual assessment and always take advice from a doctor who is familiar with the particular person.
Consult you or your child’s physician regard the specific outlook for you or your child.