Atrial Septal Defect

Cross-Section of a Normal Heart and a 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. Source:NIH

An atrial septal defect (ASD) is a hole in the part of the septum that separates the atria (upper chambers of the heart). Isolated ASDs are relatively common, accounting for about 8% of congenital heart disease. Isolated ASDs are associated with left-to-right blood shunts that may produce murmurs. ASDs may also be associated with other congenital heart defects. Over the past few decades, the diagnosis and treatment of ASDs have greatly improved. As a result, a child with a simple heart defect can grow to adulthood and live a normal, active, and productive life because his or her heart defect closes on its own or has been repaired.

Types

Doctors classify ASDs based on the:

• Size of the defect.
  • Small ASDs allow only a little blood to flow from one atrium to the other. Small ASDs don't affect the way the heart works and therefore don't need any special treatment. Many small ASDs (of the ostium secundum type) 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 are less likely to close on their own. Most children with ASDs have no symptoms, even if they have large ASDs.
• Location of the defect.
  • Ostium secundum type is a central ASD. This is the most common form of ASD (about 90%). It is often asymptomatic in children, and more than half these defects close on their own. Central ASDs are usually considered defects in the formation of septum primum (S1) and/or septum secundum (S2) in the vicinity of the foramen ovale. (Probe-patent foramen ovale, which is present in 25% of autopsies, is not considered an ASD as it is usually asymptomatic.)
  • Ostium primum type is a low ASD. This is an uncommon form of ASD (about 5%). Low ASDs are often described as a patent foramen primum and usually considered incomplete atrioventricular canal defects (or endocardial cushion defects).
  • Sinus venosus type is an uncommon form of ASD (about 5%). It is characterized by a posterior defect either high, near the superior vena cava, or low, near the inferior vena cava.
  • Coronary sinus septal type is a rare form of ASD. It is characterized by communication between the coronary sinus and left atrium, and often described as "unroofed coronary sinus".
  • Common atrium type is the absence of an interatrial septum. This is a rare form of ASD. It is thought to be caused by complete failure of formation of both the septum primum (S1) and septum secundum (S2).

Long-Term Effects of Atrial Septal Defects That Are Not Repaired

Over time, the extra blood flow to the right side of the heart and the lungs may cause problems for a heart that has an ASD. Usually, most of these problems don’t show up until adulthood, often around age 30 or later. They are rare in infants and children. These possible problems include:

• Right heart failure. The right side of the heart has to work harder to pump extra blood to the lungs. Over time, the heart may become tired from this extra work and not pump efficiently.
• Arrhythmias (irregular heartbeats). Extra blood flowing into the right atrium through an ASD can cause the atrium to stretch and enlarge. Over time, this can lead to problems with the heart’s rhythm. When this occurs, an arrhythmia can develop, with signs or symptoms such as palpitations (a feeling that your heart has skipped a beat or is beating too hard) or a rapid heartbeat.
• Stroke. Usually, the lungs filter out small clots that can form on the right side of the heart. Sometimes a blood clot formed on the right side of the heart can pass through an ASD to the left side and be pumped out to the body. A clot like this can travel to an artery in the brain, blocking blood flow through it and causing a stroke. This doesn’t occur in childhood.
• Pulmonary arterial hypertension (PAH). PAH is high blood pressure in the arteries in the lungs. Over time, high blood pressure in the lungs can damage the arteries and the small blood vessels in the lungs. They thicken and become stiff, making it harder for blood to flow through them.

These problems develop over many years and don’t occur in children. They also are rare in adults because most ASDs either close on their own or are repaired in early childhood.

Signs and Symptoms

A heart murmur (an extra flow sound associated with the heartbeat) is the most common sign of an atrial septal defect (ASD). Often, it's the only sign. However, not all murmurs are a sign of a congenital heart defect. Many healthy children have heart murmurs, which are innocent, normal sounds of blood flow through the heart. A doctor can tell by listening whether a murmur is a normal flow sound or a sign of a heart problem. Many babies born with ASDs have no signs or symptoms.

If a large ASD isn't repaired, the extra blood flow to the right side of the heart can eventually damage the heart and lungs, causing heart failure. This doesn't occur until adulthood. Signs and symptoms of heart failure can include:

• Fatigue or tiring easily during exercise or activity
• Shortness of breath
• A buildup of blood and fluid in the lungs
• A buildup of fluid in the feet, ankles, and legs

Causes

Mothers of children born with an atrial septal defect (ASD), a ventricular septal defect (VSD), or another type of heart defect often think that they did something wrong during the pregnancy to cause the problem. However, most of the time, doctors don't know why these congenital heart defects develop.

Heredity may play a role in some heart defects. For example, a parent who has a congenital heart defect is slightly more likely than other people to have a child with the problem. In very rare cases, more than one child in a family is born with a heart defect. Children with genetic defects often have congenital heart defects. An example of this is Down syndrome—half of all babies with Down syndrome have congenital heart defects.

Scientists continue to search for the causes of congenital heart defects.

Diagnosis

Exams and Tests

An ASD is diagnosed based on results from a physical exam and special tests. The exam findings for an atrial septal defect (ASD) often aren't obvious early in life, so the diagnosis is sometimes not made until later childhood or even adulthood.

Doctors who specialize in heart problems are called cardiologists. Pediatric cardiologists take care of infants, children and adolescents who have heart problems. Other specialists who treat heart defects include cardiac surgeons (doctors who repair heart defects using surgery).

Physical Exam

During a physical exam, the doctor:

• Listens to the heart and lungs with a stethoscope
• Looks for signs of a heart defect, such as a heart murmur or signs of heart failure

Diagnostic Tests and Procedures

The doctor will order several tests to diagnose an ASD or VSD. These tests also will help the doctor determine the location and size of the defect.

Echocardiography

This test, which is harmless and painless, uses sound waves to create a moving picture of the heart. During echocardiography, ultrasound waves bounce off the structures of the heart, and then a computer converts them into pictures on a video screen. The test allows the doctor to clearly see any problem with the way the heart is formed or the way it's working.

Echocardiography is an important test for diagnosing a hole in the heart and for following the problem over time. This test shows problems with the heart's structure and how the heart is reacting to these problems. Echocardiography helps the cardiologist decide whether and when treatment is needed.

EKG

An EKG (electrocardiogram) detects and records the electrical activity of the heart. This simple and painless test is used to assess the heart rhythm. An EKG shows how fast the heart is beating and whether the heart's rhythm is steady or irregular. It also can detect enlargement of one of the heart's chambers, which can help to diagnose a heart defect.

Chest X Ray

A chest x ray takes a picture of the heart and lungs. It can show whether the heart is enlarged or whether the lungs have extra blood flow or extra fluid, which can be a sign of heart failure.

Pulse Oximetry

Pulse oximetry shows how much oxygen is in the blood. A sensor is placed on the fingertip or toe (like an adhesive bandage). The sensor is attached to a small computer unit, which displays a number that indicates how much oxygen is in the blood.

Cardiac Catheterization

During cardiac catheterization, a thin, flexible tube called a catheter is put into a vein in the arm, groin (upper thigh), or neck and threaded to the heart. A dye that can be seen on an x ray is injected through the catheter into a blood vessel or a chamber of the heart. This allows the doctor to see the flow of blood through the heart and blood vessels on the x-ray image.

Cardiac catheterization also can be used to measure the pressure inside the heart chambers and blood vessels and can determine whether blood is mixing between the two sides of the heart. It's also used to repair some heart defects.

Treatment

Although many holes in the heart don't need treatment, some do. These days, most holes in the heart that need treatment are repaired in infancy or early childhood. Sometimes, adults are treated for holes in the heart if problems develop.

The treatment that a child receives depends on the type, location, and size of the hole. Other factors include the child's age, size, and general health.

Treating Atrial Septal Defect

Periodic checkups are done to see whether the defect closes on its own. About half of all ASDs close on their own over time, and about 20 percent close within the first year of life. The doctor will recommend how often a child should be checked. For an ASD, frequent checkups aren't needed. When treatment of an ASD is required, it involves catheter or surgical procedures to close the hole.

Catheter or Surgical Procedures To Repair ASD

Doctors often decide to close an ASD in children who still have medium to large holes by the time they are 2 to 5 years old.

Catheter procedure. Until the early 1990s, surgery was the usual method for closing all ASDs. Now, thanks to medical advances, catheter procedures can be used to close secundum ASDs, which are the most common type of ASD. This procedure is done under general anesthesia, so the child sleeps throughout and doesn't feel any pain.

During the procedure, the doctor inserts a catheter (a thin, flexible tube) into a vein in the groin (upper thigh) and threads it to the heart's septum. The catheter has a tiny umbrella-like device folded up inside it. When the catheter reaches the septum, the device is pushed out of the catheter and positioned so that it plugs the hole between the atria. The device is secured in place and the catheter is withdrawn from the body. Within 6 months, normal tissue grows in and over the device. There is no need to replace the closure device as the child grows.

Doctors often use echocardiography or a transesophageal echocardiography (TEE) as well as angiography to guide them in threading the catheter to the heart and closing the defect. A TEE is a special type of echocardiography that takes pictures of the heart through the esophagus (the tube leading from the mouth to the stomach).

Catheter procedures are much easier than surgery on patients because they involve only a needle puncture in the skin where the catheter is inserted. This means that recovery is faster and easier. The outlook for children having this procedure is excellent. Closures are successful in more than 9 out of 10 patients, with no significant leakage. Rarely, a defect is too large for catheter closure, so surgery is needed.

Surgery. Open-heart surgery is generally done to repair primum or sinus venosus ASDs. General anesthesia is used so the child will sleep through the operation and not feel any pain.

During this procedure, the surgeon makes an incision in the chest to reach the ASD and repairs the defect with a special patch that covers the hole. The child is placed on a heart-lung bypass machine so that the heart can be opened to perform the operation.

The outlook for children after ASD surgery is excellent. On average, children spend 3 to 4 days in the hospital before going home. Complications, such as bleeding and infection, from ASD surgery are very rare. Some children may develop inflammation of the outer lining of the heart, causing fluid to collect around the heart in the weeks after surgery. This is a reaction to the heart operation and usually resolves with medicine.

While in the hospital, the child is given medicines as needed to reduce pain or anxiety. The doctors and nurses at the hospital teach parents how to care for the child at home. They will talk about preventing blows to the chest as the incision heals, limiting activity while the child recovers, bathing, scheduling followup appointments with the doctor, and determining when the child can resume regular activities.

Living With an Atrial Septal Defect

The outlook for children with atrial septal defects (ASDs) is excellent. Advances in treatment mean that most children with these heart defects have normal, active, and productive lives with no decrease in lifespan.

Many children with these defects need no special care or only occasional checkups with a cardiologist (a doctor who specializes in heart problems) as they go through childhood and adult life.

Small ASDs often close on their own, and children with these heart defects don't have any problems or need treatment. Children and adults with small ASDs that don't close and don't cause symptoms are healthy and don't need treatment.

Many others with ASDs that don't close undergo procedures to close the hole and prevent possible long-term complications. Children recover well from these procedures and lead normal, healthy lives. Adults also do well after closure procedures.

Medical Needs

Arrhythmias. The risk of arrhythmias (irregular heartbeats) increases before and after surgery. Adults with ASDs who are older than 40 years are especially likely to have arrhythmias. People who had arrhythmias before surgery are more likely to have them after surgery.

Followup care. Regular followup care into adult life is advised for those who have had:

• An ASD repaired as an adult
• Arrhythmias before and after surgery
• An ASD repaired with a catheter procedure
• High blood pressure in the pulmonary artery at the time of surgery

Antibiotics. Some heart defects and their repairs can increase the risk of bacterial endocarditis, a serious infection of the heart valves or lining of the heart. Antibiotics may be needed before medical or dental procedures (such as surgery or dental cleanings) that could allow bacteria to enter the bloodstream. The doctor can discuss the need take antibiotics before such procedures. ASDs aren't associated with the risk of endocarditis, except in the 6 months after repair (for both catheter procedures and surgery).

Special Considerations for Children and Teens

Activity. Children with a repaired or closed ASD have no restrictions on their activity.

Growth and development. Children with ASDs don't have growth or development problems.

Regular health care. A child should see his or her regular doctor for routine health care.

Additional surgery or procedures. When a child has an ASD, but no other heart defect, additional surgery isn't needed.

Special Considerations for Adults

Recovery from surgical repair of an ASD. When an ASD is repaired in adult life, the cardiologist or surgeon will explain what to expect during the recovery period and when to return to driving, working, exercising, and other activities.

Other Resources

• Congenital Heart Defects (Diseases and Conditions Index)
• NHLBI-Related Public Interest Organizations
• Congenital Heart Disease (MedlinePlus)
• Pediatric Heart Network

Clinical Trials

• Current Research (ClinicalTrials.gov)