Atrial Septal Defect (ASD): Symptoms, Types, Causes, Diagnosis & Treatment — Complete Guide
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What Is an Atrial Septal Defect?
An atrial septal defect (ASD) is a hole present at birth in the wall between the heart's two upper chambers, sending extra blood through the lungs. Many small defects cause no problems or close on their own, but larger ones can weaken the right side of the heart. Medium and large holes are usually closed by catheter patch or surgery.
What the research says
Closing an ASD in adults improves heart function, but proof of a survival benefit is limited. A systematic review done for the 2018 AHA/ACC adult congenital heart disease guideline pooled 11 non-randomized studies (603 adults with an unrepaired secundum ASD) and found that closure improved functional class and right-ventricle pressure, size and volume; the reviewers judged the evidence low-strength and concluded there were insufficient data to determine the effect on mortality. (Oster et al., Circulation, 2019) [3]
Catheter closure in adults looks safe over about 6 years. A meta-analysis of 9 studies (1,015 adults, mean follow-up 6.4 years) found long-term mortality of 2.4% and stroke of 2.1% after transcatheter closure, with atrial arrhythmia in 6.5%, residual shunt in 4.2%, and ASD-related re-intervention in 2.3%. The authors note the quality of the available evidence varies. (Alnasser et al., Int J Cardiol, 2018) [4]
At a Glance
Topic | Key Facts |
What is it | A hole in the atrial septum (wall between the two upper heart chambers), present at birth |
How common to notice | Many small defects are found by chance and never cause concern |
Most common type | Secundum (middle of the septum) |
Typical symptoms | Shortness of breath, tiredness, swelling, palpitations — often appear in adulthood |
Main diagnostic test | Echocardiogram (sound-wave pictures of the beating heart) |
Main treatments | Catheter-based patch (secundum type) or open-heart surgery (other types) |
Serious risks if untreated | Right-sided heart failure, arrhythmias, stroke, pulmonary hypertension |
What Is an Atrial Septal Defect?
An atrial septal defect (ASD) is a heart condition you're born with — a congenital heart defect. People with an ASD have a hole between the upper heart chambers, and the hole increases the amount of blood flowing through the lungs.
The word septum refers to the wall between the chambers. The upper chambers are called the atria (singular: atrium), and the wall separating them is the atrial septum. A defect in that wall is what the name describes.
The size of the hole determines everything that follows. Small atrial septal defects might be found by chance and never cause a concern. Others might close during infancy or early childhood. But a large, long-term atrial septal defect can damage the heart and lungs, and surgery may be needed to repair it and prevent complications.
How does the heart normally work, and what does an atrial septal defect change?
A large atrial septal defect (ASD) disrupts the heart's normal blood flow, sending extra blood to the lungs and making the right side of the heart work too hard. A typical heart has two upper and two lower chambers. The upper chambers, the right and left atria, receive incoming blood. The lower chambers, the more muscular right and left ventricles, pump blood out. The heart valves act as gates at the chamber openings, keeping blood flowing in the right direction.
The right side of the heart moves blood to the lungs. In the lungs, blood picks up oxygen and returns to the heart's left side. The left side then pumps blood through the body's main artery, the aorta, out to the rest of the body.
A large atrial septal defect changes that flow. It can send extra blood to the lungs and cause the right side of the heart to work too hard. Without treatment, the right side grows larger over time and becomes weak. The blood pressure in the arteries of the lungs can also rise, causing pulmonary hypertension.
What are the four types of atrial septal defect?
Not all ASDs are the same — the location of the hole on the septum determines the type, and the type influences which treatment works.
Type | Where the Hole Is | Notes |
Secundum | Middle of the atrial septum | The most common type of ASD |
Primum | Lower part of the atrial septum | May occur with other heart conditions present at birth |
Sinus venosus | Upper part of the atrial septum | Rare; often occurs with other heart structure changes present at birth |
Coronary sinus | Wall between the coronary sinus and the left atrium | Rare; the coronary sinus is part of the heart's vein system |
What are the symptoms of an atrial septal defect?
A baby born with an atrial septal defect may not have symptoms at all. Symptoms may begin in adulthood — which is why some people live for years without knowing they have one.
When symptoms do appear, they typically include:
Symptom | How It Feels |
Shortness of breath | Especially when exercising |
Tiredness | Especially with activity |
Swelling | Of the legs, feet, or belly area |
Arrhythmias | Irregular heartbeats |
Palpitations | Skipped heartbeats or feelings of a quick, pounding, or fluttering heartbeat |
When to seek help. Serious congenital heart defects are often diagnosed before or soon after a child is born. Get emergency help right away if a child has trouble breathing.
Call a healthcare professional if these symptoms occur:
Shortness of breath, especially during exercise or activity
Easy tiring, especially after activity
Swelling of the legs, feet, or belly area
Skipped heartbeats or feelings of a quick, pounding heartbeat
What Causes an Atrial Septal Defect?
The cause of an atrial septal defect is not clear. The condition affects the structure of the heart and happens as the baby's heart is forming during pregnancy.
The following factors may play a role in the cause of congenital heart defects such as ASD:
Changes in genes
Some medical conditions
Certain medicines
Smoking
Alcohol misuse
What are the risk factors for an atrial septal defect?
An atrial septal defect forms as a baby's heart develops during pregnancy, and certain factors, including a family history of heart defects, may raise the risk. Things that may raise a baby's risk of an ASD or other heart conditions present at birth include:
Risk Factor | Why It Matters |
German measles (rubella) | During the first few months of pregnancy |
Diabetes | Raises the risk of congenital heart defects |
Lupus | An autoimmune condition linked to congenital heart defects |
Alcohol or tobacco use | During pregnancy |
Cocaine use | During pregnancy |
Some medicines | Including those used to treat seizures and mood conditions during pregnancy |
Some types of congenital heart defects occur in families — meaning they are inherited. Tell your care team if you or someone in your family had a heart condition present at birth. Screening by a genetic counselor can help show the risk of some heart defects in future children.
What are the complications of an atrial septal defect?
An atrial septal defect that is small might never cause problems and often closes during infancy. Larger defects, however, can cause serious complications:
Complication | What Happens |
Right-sided heart failure | The overworked right side of the heart weakens |
Arrhythmias | Irregular heartbeats develop |
Stroke | Blood clots can travel through the hole |
Pulmonary hypertension | High blood pressure in the lung arteries |
Eisenmenger syndrome | Pulmonary hypertension causes lasting lung damage, developing over many years in some people with large ASDs |
Early death | In the most serious untreated cases |
Treatment can prevent or help manage many of these complications.
Atrial Septal Defect and Pregnancy
If you have an atrial septal defect and are pregnant or thinking about becoming pregnant, talk to a healthcare professional first. Proper prenatal care matters, and a professional may suggest repairing the hole before getting pregnant. A large atrial septal defect or its complications can lead to a high-risk pregnancy.
How Is an Atrial Septal Defect Diagnosed?
Some atrial septal defects are found before or soon after a child is born, but smaller ones may not be found until later in life. If an ASD is present, a healthcare professional may hear a heart murmur — a whooshing sound heard when listening to the heart with a stethoscope.
Tests that help diagnose an ASD include:
Test | What It Shows |
Echocardiogram | The main test. Sound waves make pictures of the beating heart, showing the structure of the chambers and valves and how blood moves through the heart |
Chest X-ray | The condition of the heart and lungs |
Electrocardiogram (ECG or EKG) | A quick, painless test recording the heart's electrical activity; shows heart rate and helps find arrhythmias |
Cardiac MRI scan | Detailed images of the heart using magnetic fields and radio waves; used if other tests don't give a sure diagnosis |
CT scan | Detailed pictures of the heart created from a series of X-rays; used when other tests don't give enough information |
Care is usually provided by a congenital cardiologist — a doctor trained in heart conditions present at birth.
How is an atrial septal defect treated?
Treatment depends on two things: the size of the hole and whether there are other heart conditions present at birth.
An atrial septal defect may close on its own during childhood. For small holes that don't close, regular health checkups may be the only care needed. Some defects that don't close need treatment to close the hole — but closure is not recommended for people who have severe pulmonary hypertension.
Medicines
Medicines won't repair an atrial septal defect, but they can help lessen symptoms:
Beta blockers — to control the heartbeat
Anticoagulants (blood thinners) — to lower the risk of blood clots
Diuretics — to lessen fluid buildup in the lungs and other parts of the body
Closing the Hole: Catheter Repair vs. Surgery
Treatment is often suggested to repair a medium to large ASD to prevent future complications. Repair means closing the hole, and it can be done in two ways:
Method | How It Works | Which Types It Treats |
Catheter-based repair | A thin, flexible tube (catheter) is put into a blood vessel, most often in the groin, and guided to the heart. A mesh patch or plug closes the hole, and heart tissue grows around the patch, closing the hole for life | Secundum type only; some large secundum defects may still need open-heart surgery |
Open-heart surgery | A cut is made through the chest wall to reach the heart, and surgeons use patches to close the hole | The only way to fix primum, sinus venosus, and coronary sinus defects |
Sometimes the repair can be done through smaller cuts than traditional surgery — a method called minimally invasive surgery. If the repair is done with a robot's help, it's called robot-assisted heart surgery.
Anyone who has had surgery for an atrial septal defect needs regular imaging tests and health checkups to watch for possible heart and lung complications.
People with large defects who do not have surgery to close the hole often have worse long-term outcomes. They may develop reduced functional capacity — more trouble doing everyday activities — and face greater risk of irregular heartbeats and pulmonary hypertension.
Which lifestyle habits and home remedies help people with an atrial septal defect?
People with an atrial septal defect should follow a heart-healthy lifestyle that includes eating healthy, not smoking, managing weight and getting enough sleep. If you or your child has an ASD, talk to your healthcare team about the following:
Exercise. Exercise is usually OK for people with an ASD. But if repair is needed, you might have to stop some activities until the hole is fixed. Ask a healthcare professional what type and amount of exercise is safest.
Extreme altitude changes. Extreme changes in location above or below sea level may cause complications in people with an unfixed ASD. There is less oxygen at higher altitudes, which changes blood flow through the lung arteries — this can cause shortness of breath and strain the heart.
Dental work. If you or your child recently had an ASD fixed and needs dental work, talk to a healthcare professional. Antibiotics may be needed for about six months after repair surgery to prevent infection.
Can You Prevent an Atrial Septal Defect?
Preventing an atrial septal defect may not be possible because its cause is not clear. But good prenatal care is important. If you were born with an ASD, make an appointment for a health checkup before becoming pregnant. During this visit:
Talk about current health conditions and medicines. Diabetes, lupus, and other conditions need close management during pregnancy. Your healthcare professional may suggest changing doses of some medicines or stopping them before pregnancy.
Review your family medical history. If you have relatives with congenital heart defects or other genetic conditions, consider talking with a genetic counselor to learn about your risks.
Ask about rubella testing. Rubella in a pregnant person has been linked to some types of congenital heart defects. If you haven't had German measles or the vaccine, get the recommended vaccinations.
How can families cope with an atrial septal defect and find support?
Living with a congenital heart condition raises questions, and you don't have to sort them out alone. Support groups connect people living with heart and blood conditions with others like them, for shared support and answers to everyday questions.
How should you prepare for an atrial septal defect appointment?
A doctor trained in heart conditions present at birth — a congenital cardiologist — usually provides care for people with an ASD. Here's how to get ready.
What You Can Do
Make a list of:
Your or your child's symptoms, and when you noticed them
Important personal information, including major stresses, recent life changes, and any family history of heart conditions present at birth
All medicines, vitamins, or supplements being taken, including dosages
Questions to ask during your appointment
Questions to ask might include:
What's the most likely cause of these symptoms?
Are there other possible causes?
What tests are needed?
Is the atrial septal defect likely to close on its own?
What are the treatment choices?
What are the risks of repair surgery?
Are there any activity restrictions?
Are there brochures or other printed material I can have? What websites do you recommend?
What to Expect from Your Doctor
Your healthcare professional is likely to ask:
Do you or your child always have symptoms, or do they come and go?
Do symptoms get worse with exercise?
Does anything else seem to make the symptoms worse?
Is there anything that seems to make the symptoms better?
Is there a family history of congenital heart defects?
Frequently Asked Questions
What is an atrial septal defect?
An atrial septal defect (ASD) is a hole in the wall (atrial septum) between the heart's two upper chambers that is present at birth. The hole increases the amount of blood flowing through the lungs.
Does an atrial septal defect always need surgery?
No. Small defects may be found by chance and never cause concern, and some close on their own during infancy or childhood — needing only regular checkups. Medium to large defects are usually repaired to prevent complications.
What are the symptoms of an ASD in adults?
The most common adult symptoms are shortness of breath during exercise, tiredness with activity, swelling of the legs, feet, or belly, and irregular or pounding heartbeats (palpitations). Many babies have no symptoms at all.
How is an atrial septal defect diagnosed?
A doctor may first hear a heart murmur — a whooshing sound — with a stethoscope. The main diagnostic test is an echocardiogram, which uses sound waves to picture the beating heart; chest X-ray, ECG, cardiac MRI, and CT scans may also be used.
How is the hole in the heart closed?
The secundum type (middle of the septum) can be closed with a catheter-based repair using a mesh patch or plug guided through a blood vessel. The other three types — primum, sinus venosus, and coronary sinus — require open-heart surgery with patches.
Can you live a normal life with an atrial septal defect?
Yes, especially when the defect is small or has been repaired. Exercise is usually OK, but extreme altitude changes can strain an unfixed heart, and people who had repair surgery may need antibiotics before dental work for about six months.
Is an atrial septal defect inherited?
Some types of congenital heart defects run in families, and family history raises the risk for other children. A genetic counselor can help assess the risk of heart defects in future children.
Conclusion
The most important lessons from this guide are simple to remember. First, an atrial septal defect is a hole between the heart's upper chambers present at birth — and its size, not its existence, determines whether it matters. Second, symptoms such as breathlessness with exercise, unexplained tiredness, swelling, and pounding heartbeats can stay hidden for decades, which is why follow-up after childhood murmurs matters. Third, modern medicine closes the gap effectively — with a catheter patch for the most common type or surgery for the rarer forms — and treatment prevents the serious complications of heart failure, stroke, and lung damage.
This article walked you through all four ASD types, the symptom checklist, the risk factors you can't control, the five diagnostic tests, and every treatment option from watchful waiting to robot-assisted surgery, so you can recognize the signs and know exactly what questions to ask your care team.
Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
Related Reading
ASD Closure: Procedure, Risks and Recovery explains ASD closure.
Bubble Study (Bubble Echo): Finding PFO, ASD and Lung Shunts explains the saline bubble ultrasound test that finds holes in the heart.
References
Mayo Clinic. Atrial septal defect (ASD) — Symptoms & causes. Accessed October 12, 2026. https://www.mayoclinic.org/diseases-conditions/atrial-septal-defect/symptoms-causes/syc-20369715
Mayo Clinic. Atrial septal defect (ASD) — Diagnosis & treatment. Accessed October 12, 2026. https://www.mayoclinic.org/diseases-conditions/atrial-septal-defect/diagnosis-treatment/drc-20369720
Oster M, Bhatt AB, Zaragoza-Macias E, et al. Interventional therapy versus medical therapy for secundum atrial septal defect: a systematic review (part 2) for the 2018 AHA/ACC guideline for the management of adults with congenital heart disease. Circulation. 2019;139(14):e814-e830. PMID 30586769. https://doi.org/10.1161/CIR.0000000000000605
Alnasser S, Lee D, Austin PC, et al. Long term outcomes among adults post transcatheter atrial septal defect closure: systematic review and meta-analysis. Int J Cardiol. 2018;270:126-132. PMID 30054146. https://doi.org/10.1016/j.ijcard.2018.06.076
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