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Atrial Septal Defect

Congenital Atrial Septal Defects (ASD)

The heart is divided into four separate chambers. The upper chambers, or atria, are divided by a wall called the septum. An atrial septal defect (ASD) is a hole in that septum. Atrial septal defects are one of the most common heart defects seen.

When an atrial septal defect is present, blood flows through the hole primarily from the left atrium to the right atrium. This shunting increases the blood volume in the right atrium which means more blood flows through the lungs than would normally.

If left untreated, atrial septal defect may cause problems in adulthood. These problems may include pulmonary hypertension (which is high blood pressure in the lungs), congestive heart failure (weakening of the heart muscle), atrial arrhythmias (which are abnormal rhythms or beating of the heart) and an increased risk of stroke.

Signs and Symptoms of ASD

In most children, atrial septal defects cause no symptoms. A very large defect may allow so much blood flow through it to cause congestive heart failure symptoms such as shortness of breath, easy fatigability, or poor growth, but this is uncommon.

Most often an atrial septal defect is diagnosed when a physician hears a heart murmur during a physical examination.

The murmur doesn't actually come from blood going across the hole, but rather from the pulmonary valve area because the heart is forcing an unusually large amount of blood through a normal sized valve.

The second heart sound is characteristically "split" which is different than what is heard when listening to a normal heart.

Diagnosis of ASD

Hearing a murmur on a physical exam is the most common reason an atrial septal defect is suspected. Echocardiography is the primary method used to confirm the presence of an atrial septal defect.

Echocardiography can show not only the hole and its size, but also any enlargement of the right atrium and ventricle in response to the extra work they are doing.

An electrocardiogram (EKG) may show evidence of thickening of the heart muscle and a chest X-ray may show enlargement of the heart and increased blood flow to the lungs.

Treatment for ASD

In some children, an ASD may close on its own without treatment. With a small atrial septal defect, the rate of spontaneous closure may be as high as 80 percent in the first 18 months of life. An ASD still present by 3 years of age will probably never close on its own.

Open-Heart Surgery

Although an atrial septal defect may be closed by open-heart surgery, this approach is not as common as it once was now that transcatheter closure devices are readily available. Should open heart surgery be deemed necessary, the surgeon may be able to directly close the hole with sutures or, depending on the size and shape of the hole, may need to close it with a patch. Surgery is very effective and carries a low risk profile.

Transcatheter Device Closure

Depending on the size and the area of the septum involved, many atrial septal defects may be closed by placement of a device during a cardiac catheterization. This device is inserted through a catheter and covers the ASD by attaching to the atrial septum. A catheter is a long thin tube, about the diameter of a piece of spaghetti, which is directed to the heart through the large blood vessels in the groin.

The benefits of being able to close an atrial septal defect with a transcatheter device is that it can be put in place without stopping the patient's heart or utilizing cardiopulmonary bypass, it doesn't have the psychological trauma related to open-heart surgery and it doesn't create a scarring across the chest the way open-heart surgery does. 

Two FDA-approved devices are currently available in the United States and readily used in the catheterization laboratory.  These include the Amplatzer Septal Occluder and the Helex Septal Occluder.

Atrial Septal Defect Closure Results

Surgical closure of atrial septal defects is complication free in more than 99 percent of cases. Although the Amplatzer device has only been utilized for a decade, its success rate also appears to be very high. After ASD closure in childhood, the heart size returns to normal over a period of four to six months.

Following closure of an atrial septal defect, there should be no problems with physical activity and no restrictions. Regular follow-up appointments will be made with a cardiologist; regardless of closure mode, mid-term and late problems can occur. 

Adult and Adolescent Management

An atrial septal defect can be discovered for the first time in adult life. An atrial septal defect is a term describing a hole between the two upper chambers of the heart. In most patients this causes increased blood flow to the lungs, and also causes enlargement of the right heart chambers (right atrium and right ventricle). ASDs come in various sizes, and a small ASD may have no significant effect on a person’s health. If ASDs are large enough to cause enlargement of the right heart chambers, repair is recommended to protect the patient from physical deterioration and to attempt to normalize patient survival. Secundum ASDs are the most common form, and can usually be closed nonsurgically using a device. The other forms of ASDs require surgical correction.  These are typically low-risk procedures. Nonetheless, congenital surgical expertise can be very important to ensure the best outcome.

Adults who have had an ASD closed or repaired surgically need periodic evaluation depending on their own personal circumstances.  Patients who have had device closure of ASDs should probably have an echo every five years or so looking for complications of the device. Patients who had some high blood pressure in their lungs before the ASD was closed should be followed periodically. Other adults will have had rhythm problems such as atrial flutter or atrial fibrillation that may require ongoing monitoring and often treatment.

Learn more about the Adolescent and Adult Congenital Heart Disease Program.

Last Updated 08/2021

Reviewed By Abby Rodgers, RN