Atrial Septal Defect (ASD)

What is an atrial septal defect?

Atrial septal defect (ASD) is the second most common congenital heart defect, accounting for 10-15% of all congenital heart defects. They occur almost twice as frequently in girls. Atrial septal defects commonly occur in otherwise normal hearts but may be associated with other heart defects including pulmonary stenosis, ventricular septal defect, partial anomalous venous return, patent ductus arteriosus, mitral valve prolapse, and other more complex heart anomalies. The information on this page applies to patients with an atrial septal defect and an otherwise normal heart. An atrial septal defect is a defect or hole in the wall that separates the upper two chambers of the heart (1). The upper chambers of the heart are called the atria (2) and the wall between them is called the atrial septum. Atrial septal defects are categorized by size and location. The size of the defect is usually described as small, moderate, or large. Precise measurement of defect size in millimeters can be provided by an echocardiogram. ASDs are further categorized by location of the defect within the atrial septum. Terms used to describe defect location include secundum, primum and sinus venosus atrial septal defects. Secundum atrial septal defects account for 80% of atrial septal defects and are located near the middle of the atrial septum. Sinus venosus ASDs are located high on the atrial wall near where the superior vena cava enters the heart (3). This type of defect is frequently associated with abnormalities in the pulmonary veins (4) that return blood flow from the lungs to the left atrium (left upper chamber). The third type of defect, primum atrial septal defect, is discussed in the section about atrioventricular septal defects. Rarely, children are born with complete absence of the atrial septum. About 50% of atrial septal defects close as the heart grows during childhood. Large atrial septal defects (measuring >8mm in diameter) are much less likely to close on their own.

What are the effects of this problem on my child's health?

Even if the atrial septal defect is large, there are usually minimal or no symptoms during infancy and childhood. Occasionally, infants with large atrial septal defects develop symptoms of congestive heart failure. Some children have problems with fatigue and/or shortness of breath with exercise. Health related effects of even large atrial septal defects generally do not occur before the third decade of life. Possible long term effects of moderate and large atrial defects include pulmonary artery hypertension, congestive heart failure, and abnormal heart rhythms (arrhythmias). Pulmonary artery hypertension is the result of excessive pulmonary artery pressure caused by extra pulmonary blood flow. The size of the defect determines how much blood returns to the right heart and to the lungs. Large defects allow up to 2 to 3 times the ordinary amount of blood to circulate through the heart's right side. Over time this results in enlargement of the right atrium and the right ventricle due to the extra workload. In response to the extra blood flow, the wall of the pulmonary arteries becomes thick and stiff leading to a condition called pulmonary vascular obstructive disease.This is a very serious problem with few available treatment options. Congestive heart failure is also related to the extra workload caused by recirculation of blood to the right side of the heart. If the heart is unable to meet the body's needs, symptoms of heart failure develop, a process that usually occurs slowly over a period of time. Long term effects of moderate to large atrial septal defects can include abnormal heart rhythms, most often atrial flutter or atrial fibrillation. This problem is related to stretching of the atrial chamber from the extra blood flow. This creates a situation where the heart's upper chambers can start to beat very rapidly causing symptoms of palpitations, dizziness, fainting, and/or undue fatigue. Another possible health problem related to an atrial septal defect is stroke. Stroke can occur when small blood clots travel across the defect and out the left side of the heart to the brain. Fortunately, this problem is quite rare and almost never occurs in children. The presence of a small atrial septal defect may be an important factor for adults with otherwise unexplained stroke. For this reason, closure of even small atrial septal defects may be a good option for these patients. Infective endocarditis is extremely rare so people with isolated atrial septal defects do not need to observe SBE prophylaxis except for a period of six months after surgical or catheter closure of the defect. Exercise recommendations: Exercise recommendations are best made by a patient's doctor so that all relevant factors can be included in the decision. In general, exercise restrictions for patients with repaired or unrepaired atrial septal defects are not necessary and children can participate in competitive and vigorous athletic activities.

How is this problem diagnosed?

Clinical features: Most infants and children with ASD do not exhibit symptoms even if the defect is large. Occasionally, infants with large ASD develop symptoms of congestive heart failure. Some older children have shortness of breath with exercise and lower stamina than their peers. Physical findings: The diagnosis is most often made due to the presence of a heart murmur and/or an abnormal second heart sound. Growth and development is expected to be normal although many of the children have a slender body build. Since most children are without symptoms and the physical findings are subtle, it is not uncommon for the diagnosis to be made in late childhood or adolescence. Medical tests: In patients with a significant atrial septal defect, the electrocardiogram often shows increased right ventricular forces and may show right atrial enlargement. The chest x-ray often shows a larger than normal heart size with evidence for increased pulmonary blood flow. An echocardiogram is able to detect even small atrial septal defects with almost 100% accuracy and permits measurement of the size and description of the precise location of the defect on the atrial septum. Cardiac catheterization is rarely needed for diagnostic purposes but may be done if there is concern about pulmonary artery hypertension, the pulmonary veins, or other diagnostic questions. Closure of the defect during a heart catheterization may be done to treat the problem.

How is the problem treated?

Indications for closure of an atrial septal defect Closure of an atrial septal defect is done if there is persistence of a moderate to large defect when the child is between four and six years of age. If the defect is diagnosed in young adulthood, the benefits of closure remain significant. Although the benefits of closure of significant defects diagnosed in later adulthood are less clear, there is evidence that closure will improve health for many older patients. Surgical closure of atrial septal defects Atrial septal defects can be closed surgically. The procedure involves either placement of sutures that pull the hole closed or placement of a patch that is sewn over the edges of the defect. The chest wall incision is kept very short to improve cosmetic results and can be made either in the center of the chest or on the right side. Blood transfusions are rarely required and the total hospital length of stay is usually 3 or 4 days. Surgical results are excellent and complete closure of the defect is accomplished in virtually every case. Complications are rare but may include bleeding, infection, or a collection of fluid around the heart. Transcatheter closure of atrial septal defects Another treatment option for some patients is transcatheter closure of the defect. This procedure is done in the heart catheterization laboratory and avoids the need for surgery. Closure devices have been evolving since 1974 and are still investigational so current use is limited. More recent devices are the Angel Wing device, the ASDOS device, the Buttoned device, the Cardioseal device, and the Amplatzer device. As transcatheter ASD closure affords many advantages related to the avoidance of open heart surgery and anesthesia, it is anticipated that investigations into this approach will continue and that transcatheter closure will become a common treatment option for patients with ASD. Not all patients with atrial septal defects are candidates for transcatheter closure. Factors which must be considered include size of the defect, position of the defect within the atrial septum (a rim of septal tissue all the way around the defect is needed to secure the device), and age (and size) of the patient. During the procedure, catheters (thin plastic tubes) are placed into the large blood vessels in the legs and "floated" into the heart. The closure device is delivered to the site of the defect collapsed within a catheter. After the catheter tip is moved into place, the device is pushed out of the catheter, across the atrial septal defect, and secured in place. This procedure is done with IV sedation and usually the patient can go home the same day.

Clinics

Care and services for patients with this problem are provided in the Congenital Heart, Interventional Cardiology and Cardiovascular Surgery clinics at the University of Michigan Medical Center in Ann Arbor.

References

Behrendt DM. Atrial septal defect. In C Mavroudis & C Backer (Eds) Pediatric Cardiac Surgery. St. Louis, MO: Mosby, 1994, 93-200. Helgason H & Jonsdottir G. Spontaneous closure of atrial septal defects. Pediatr Cardiol 20: 1999;195-199) Latson LA. Per-catheter ASD closure. Pediatr Cardiol 19:86-93, 1998. Written by: S. LeRoy RN, MSN Reviewed September, 2012