What Is Atrial Septal Defect? Symptoms And Treatment

An atrial septal defect (ASD) is a hole in the wall that separates the two upper chambers of the heart, known as the atria. This is a birth defect that is present from the start, and it can cause blood to flow from the left side of the heart to the right side, forcing the heart and lungs to work harder than they should. While small defects may close on their own or cause no problems, larger ones often require medical treatment to prevent long-term complications.

What Is Atrial Septal Defect Symptoms And Treatment?

An atrial septal defect is exactly what the name says: a hole in the atrial septum. The atrial septum is the muscular wall that divides the left atrium and the right atrium. Before birth, this opening is normal and necessary because it allows blood to bypass the lungs, which are not yet in use. In most babies, this opening closes shortly after birth. When it does not close completely, the result is an ASD.

The size and location of the hole determine how much trouble it causes. A small hole may never cause symptoms. A larger hole allows a significant amount of oxygen-rich blood from the left atrium to mix with oxygen-poor blood in the right atrium. This extra blood then flows into the lungs, and over time, the extra workload can enlarge the right side of the heart and raise pressure in the lung’s blood vessels.

Treatment depends on the size of the defect, the symptoms, and the person’s age. Some small defects close on their own during childhood. Others need a procedure to close the hole, either with a catheter-based device or with surgery.

What Causes an Atrial Septal Defect?

The exact cause of most atrial septal defects is not known. It is a congenital heart defect, meaning it develops during the first weeks of pregnancy when the fetal heart is forming. In most cases, there is no clear reason why the septum fails to close completely.

Some factors are associated with a higher risk of having a baby with a congenital heart defect. These include genetic conditions such as Down syndrome, a family history of heart defects, and certain infections during pregnancy, such as rubella. Some studies also suggest that poorly controlled diabetes during pregnancy or exposure to certain medications or alcohol may increase the risk. However, most babies born with an ASD have no known risk factors at all.

What Are the Symptoms of an Atrial Septal Defect?

Many people with a small ASD have no symptoms at all. The defect may only be found when a doctor hears a heart murmur during a routine checkup. A heart murmur is an extra or unusual sound made by blood flowing through the heart.

When symptoms do occur, they can be subtle and are often mistaken for other conditions. Common symptoms include:

• Shortness of breath, especially during exercise
• Fatigue and weakness
• Heart palpitations or a feeling of a racing heartbeat
• Swelling in the legs, feet, or abdomen
• Frequent lung infections in children

In infants, a large ASD may cause poor feeding, slow weight gain, and rapid breathing. Some children with a significant defect may not grow or develop at the same rate as their peers. Many adults who have an ASD are diagnosed in their 30s or 40s, often after experiencing shortness of breath or palpitations that prompt a medical evaluation.

How Is an Atrial Septal Defect Diagnosed?

A doctor may suspect an ASD after listening to the heart and hearing a characteristic murmur. To confirm the diagnosis, the doctor will usually order an echocardiogram. This test uses sound waves to create a moving picture of the heart and can show the size and location of the hole, as well as how much blood is passing through it.

Other tests may be used to get more information. An electrocardiogram (ECG) records the electrical activity of the heart and can show signs of an enlarged right atrium or ventricle. A chest X-ray can reveal an enlarged heart or extra blood flow to the lungs. In some cases, a cardiac MRI or a cardiac catheterization may be needed to measure pressures inside the heart and lungs precisely.

What Complications Can an Atrial Septal Defect Cause?

If a large ASD is left untreated, the extra blood flow to the lungs can cause problems over time. The right side of the heart can become enlarged because it is working harder to pump the extra volume. This can eventually lead to heart failure, a condition in which the heart cannot pump enough blood to meet the body’s needs.

Pulmonary hypertension is another serious complication. This is high blood pressure in the arteries of the lungs. Over many years, the increased blood flow can damage the small blood vessels in the lungs, causing them to become stiff and narrow. If this progresses far enough, it can reverse the direction of blood flow through the hole, a condition called Eisenmenger syndrome. Once this occurs, the ASD is usually no longer safe to close surgically.

People with an ASD also have a higher risk of developing an abnormal heart rhythm called atrial fibrillation. This is because the enlarged atria can disrupt the heart’s normal electrical signals. A less common but serious complication is a stroke, which can happen if a blood clot travels from the right side of the heart through the hole and into the brain.

How Is an Atrial Septal Defect Treated?

The treatment plan depends on the size of the defect, the person’s age, and whether symptoms are present. Small defects that do not cause symptoms may not need any treatment. A doctor will monitor the condition with regular checkups and echocardiograms to make sure it is not getting worse.

For larger defects, or for defects that cause symptoms, closure is usually recommended. There are two main ways to close an ASD. The first is a catheter-based procedure called transcatheter closure. A thin tube is inserted into a blood vessel in the leg and guided up to the heart. A small mesh device is then placed through the tube and positioned over the hole to seal it. This procedure does not require open-heart surgery and recovery time is shorter.

The second option is open-heart surgery. The surgeon makes an incision in the chest, opens the heart, and patches the hole with a piece of synthetic material or a piece of the patient’s own pericardium, which is the sac that surrounds the heart. This approach is used when the hole is too large or too oddly shaped for a catheter-based device.

Medication does not close an ASD, but it can manage symptoms. Diuretics can reduce fluid buildup, and medications to control heart rate can help with palpitations. These are used when a person is not a candidate for closure or is waiting for a procedure.

When Is the Best Time to Treat an Atrial Septal Defect?

In children, small defects that are not causing symptoms are often watched to see if they close on their own. If a defect has not closed by school age, or if it is causing symptoms, closure is usually recommended. Treating the defect before it causes permanent damage to the lungs and heart is the goal.

In adults, the decision to close an ASD depends on the size of the defect and the presence of symptoms. Adults with a significant shunt, meaning a large amount of blood flowing through the hole, are generally advised to have it closed even if they feel fine. This is because the risk of complications increases with age. However, if pulmonary hypertension has already become severe and fixed, closure may no longer be safe. A specialist will perform tests to assess the pressures in the lungs before recommending closure.

What Is Recovery Like After ASD Closure?

Recovery depends on the type of procedure. After a catheter-based closure, most people stay in the hospital for one night and can return to normal activities within a week. The doctor will usually recommend taking aspirin for several months to prevent blood clots from forming on the device while the heart tissue grows over it.

After open-heart surgery, recovery takes longer. The hospital stay is usually several days, and it can take six to eight weeks to fully recover at home. The chest incision needs time to heal, and heavy lifting and strenuous exercise are restricted during this period. Most people feel significantly better after recovery because their heart no longer has to work as hard.

Can an Atrial Septal Defect Be Prevented?

Because the cause of most ASDs is unknown, there is no guaranteed way to prevent them. However, expectant mothers can take steps to reduce the general risk of congenital heart defects. Getting vaccinated against rubella before becoming pregnant, managing chronic conditions like diabetes, and avoiding alcohol and illicit drugs during pregnancy are all recommended. Taking a prenatal vitamin with folic acid is also standard advice, as folic acid helps prevent certain birth defects.