Atrial Septal Defect

An atrial septal defect is a heart condition you’re born with, where there’s a hole in the wall between the heart’s upper chambers. While many small holes cause no problems and may close on their own, larger ones can affect the heart and lungs over time, requiring medical intervention to prevent complications.

Table of contents

• What Is an Atrial Septal Defect?
• Types of Atrial Septal Defects
• Signs and Symptoms
• Causes and Risk Factors
• How Common Is This Condition?
• Diagnosis
• Treatment Options
• Possible Complications
• Living With an Atrial Septal Defect

What Is an Atrial Septal Defect?

An atrial septal defect, often called ASD, is a heart problem that you’re born with. The term “congenital” means present at birth^[1]. This condition involves a hole in the wall, called the septum, that divides the upper chambers of your heart. These upper chambers are called atria^[2].

• Heart
• Atria (upper heart chambers)
• Atrial septum (wall between atria)
• Lungs

When this opening is present, blood can flow between the two upper chambers in an abnormal way. Normally, oxygen-rich blood flows from the left upper chamber down to the left lower chamber, and then out to supply oxygen to your body. With an atrial septal defect, some blood from the left atrium flows through the hole into the right atrium^[7]. This means the right side of the heart receives extra blood that ultimately goes back to the lungs again, even though it already has oxygen.

The hole can vary in size. Very small defects, less than 5 millimeters, may not cause any problems^[7]. When the hole is small and doesn’t strain your heart or lungs, the atrial septal defect can often be left alone without treatment. However, larger holes can lead to problems with your heart or lungs over time. The bigger the defect, the more likely it is to cause symptoms and need treatment^[2].

Types of Atrial Septal Defects

There are four main types of atrial septal defects, and each has a different location in the wall between the upper heart chambers^[1]:

• Secundum defect: This is the most common type, occurring in about 8 out of 10 cases. It happens in the middle of the wall between the upper heart chambers^[2].
• Primum defect: This type affects the lower part of the wall between the upper heart chambers. It might occur along with other heart problems present at birth, such as defects in the wall between the lower chambers or problems with heart valves^[1].
• Sinus venosus defect: This is a rare type that most often happens in the upper part of the wall between the heart chambers. It often occurs with other heart structure changes present at birth^[1].
• Coronary sinus defect: This is the rarest type. It involves a missing or incomplete wall between the coronary sinus, which is part of the vein system of the heart, and the left upper heart chamber^[1].

Signs and Symptoms

Many babies born with an atrial septal defect do not have symptoms^[1]. Even though the defect is present at birth, many people don’t experience symptoms until far into adulthood^[2]. Small atrial septal defects, less than 5 millimeters, may not cause symptoms because they don’t strain the heart or lungs.

The most common sign of an atrial septal defect is a heart murmur, which is a whooshing sound that a healthcare provider can hear when listening to the heart with a stethoscope^[2]. Sometimes this may be the only sign detected.

When children do have symptoms from an atrial septal defect, they may include^[2]:

• Weight that’s less than what it should be
• Growth delays
• Recurrent respiratory infections
• Fatigue when physically active (rarely)
• Trouble breathing (rarely)
• Abnormal heart rhythms (rarely)

Larger or more severe defects in children might cause additional signs such as poor appetite, poor growth, extreme tiredness, shortness of breath, or lung problems and infections like pneumonia^[6].

Adults with an atrial septal defect may feel symptoms by age 40. These symptoms depend on how much the condition has strained the heart and lungs and may include^[2]:

• Fatigue or tiredness, especially with activity
• Shortness of breath, especially when exercising
• Heart palpitations (feeling the heartbeat)
• Fast heartbeat
• Swelling in the legs, feet, or belly area
• Blue skin color
• Irregular heartbeats

Causes and Risk Factors

An atrial septal defect happens during the development of a baby’s heart in the womb. As the baby develops, the heart forms from a large tube that divides into sections that eventually become its walls and chambers. If there’s a problem during this process, a hole can form in the wall that divides the left atrium from the right^[6].

In most cases, the causes of atrial septal defects among babies are unknown. However, several factors have been identified that may increase risk^[4]:

• Genetic factors: In some cases, the tendency to develop an atrial septal defect might be inherited. Some babies have heart defects because of changes in their genes or chromosomes^[5].
• Genetic syndromes: Atrial septal defects are noted in people with syndromes such as Down syndrome, Treacher-Collins syndrome, Turner syndrome, and Noonan syndrome^[4].
• Maternal exposures: Exposure to rubella and drugs like cocaine and alcohol during pregnancy may predispose the unborn baby to developing an atrial septal defect^[4].

It’s also not clear why atrial septal defects are more common in girls than in boys^[6].

How Common Is This Condition?

Atrial septal defect is one of the most common types of congenital heart defects, affecting about 25% of children with heart conditions^[4]. About 13 of every 10,000 babies in the United States are born with an atrial septal defect. This means that about 5,240 babies are born with this condition each year^[5].

Diagnosis

An atrial septal defect may be diagnosed during pregnancy or after the baby is born. In many cases, the defect may not be diagnosed until adulthood^[5].

During pregnancy, screening tests may detect an atrial septal defect. An ultrasound, a tool that creates pictures of the baby, may show the defect. However, detection usually depends on the size of the hole and its location^[5].

After birth, an atrial septal defect is often found by detecting a heart murmur when listening to a person’s heart with a stethoscope^[5]. If a murmur is heard or other symptoms are present, the healthcare provider will request more tests to confirm the diagnosis.

Tests that help diagnose an atrial septal defect include^[9]:

• Echocardiogram: This is the main test used to diagnose an atrial septal defect. Sound waves are used to make pictures of the beating heart. An echocardiogram shows the structure of the heart chambers and valves and how well blood moves through the heart.
• Chest X-ray: This test shows the condition of the heart and lungs.
• Electrocardiogram (ECG or EKG): This quick and painless test records the electrical activity of the heart. It can show how fast or how slow the heart is beating and can help find irregular heartbeats.
• Cardiac magnetic resonance imaging (MRI) scan: This imaging test uses magnetic fields and radio waves to make detailed images of the heart. It might be done if other tests didn’t provide a sure diagnosis.
• Computerized tomography (CT) scan: This test uses a series of X-rays to create detailed pictures of the heart. It may be used if other tests don’t give enough information to make a diagnosis.
• Cardiac catheterization: In some cases, this procedure may be used to assess the amount of blood flowing through the defect^[7].

Treatment Options

Treatment for atrial septal defect depends on several factors, including the age at diagnosis, the number or seriousness of symptoms, the size of the hole, and the presence of other conditions^[9].

Monitoring: Small atrial septal defects may not need treatment if there are few or no symptoms, or if the defect is small^[7]. In childhood, small defects often close spontaneously. With a small defect, the healthcare provider may monitor it to see if the hole closes on its own^[5].

Medications: While medications can be prescribed to help treat symptoms, there are no known medications that can repair the hole itself^[5]. Patients with significant volume overload or irregular heart rhythms may require specific medicines, such as diuretics or drugs for abnormal heart rhythms^[16].

Catheter-based procedure: A procedure has been developed to close the defect without open heart surgery. Some people with atrial septal defects may be able to have this procedure, depending on the size and location of the defect. The procedure involves placing a closure device into the heart through tubes called catheters. The doctor makes a tiny 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 defect and the hole is closed^[7].

Surgery: If the defect causes a large amount of blood flow between chambers, the heart is swollen, or symptoms occur, surgery to close the defect is recommended^[7]. Sometimes open-heart surgery may be needed to repair the defect, especially when other heart defects are present. For both children and adults, surgical death rates for uncomplicated secundum atrial septal defects are less than 1%^[16].

People who have a repair to close an atrial septal defect should get antibiotics before certain dental procedures in the period following the procedure^[7].

Possible Complications

An atrial septal defect that isn’t treated in childhood can lead to health problems later in life^[6]:

• Abnormal heart rhythm: Irregular heartbeats can develop over time.
• Problems with heart pumping: The heart may have difficulty pumping blood effectively.
• Stroke risk: As people with atrial septal defects get older, they might be at increased risk for stroke because a blood clot could form, pass through the hole in the septum, and travel to the brain^[6].
• Pulmonary hypertension: High blood pressure in the lungs may develop over time, especially in older patients with larger untreated defects^[6]. Over time, the extra blood going through the hole can damage the blood vessels of the lungs^[15].
• Heart failure: When blood flows between the two heart chambers through the defect, it can strain the heart. This can cause the right side of the heart to enlarge. Over time, pressure in the lungs may build up^[7].

Long-term prevention of death and complications is best achieved when the atrial septal defect is closed before age 25 years and when the pressure in the main lung artery is less than 40 mm Hg^[16].

Living With an Atrial Septal Defect

People with this condition should schedule routine checkups with a heart doctor to stay as healthy as possible^[5]. Follow-up care is a key part of treatment and safety^[18].

Important steps for managing life with an atrial septal defect include^[18]:

• Take medicines as prescribed: Follow your doctor’s instructions exactly for any medications.
• Eat heart-healthy foods: Include vegetables, fruits, nuts, beans, lean meat, fish, and whole grains. Limit alcohol, sodium, and sugar.
• Get regular exercise: Try for 2½ hours a week. If you do not have other heart or lung problems, you likely do not have limits on the type or level of activity. Walking, swimming, biking, or other activities are usually fine. Ask your doctor what level of exercise is safe for you.
• Stay at a healthy weight: Lose weight if needed.
• Do not smoke: Smoking can make heart problems worse.
• Manage other health problems: Control high blood pressure, high cholesterol, and diabetes.
• Avoid infections: Get the flu vaccine every year. Talk with your doctor about getting a pneumonia vaccine. Stay up to date on COVID-19 vaccines.
• Prevent heart infections: Congenital heart disease can increase the risk of an infection in the heart. Talk to your doctor about your own risk. You may need to take antibiotics before certain dental or surgical procedures. Also, take good care of your teeth and gums^[18].

If you do not have other heart or lung problems, you likely do not have limits on the type or level of physical activity you can do^[18]. Both methods of closure, whether through catheter or surgery, result in excellent outcomes with no significant differences in survival, functional capacity, irregular heartbeats, or stroke events^[16].