Atrial Septal Defects Symptoms: Common Causes, Related Conditions, and When to See a Doctor

Atrial septal defects symptoms vary widely. Some people have no symptoms for years, while others notice shortness of breath, tiredness, palpitations, or reduced exercise tolerance as the heart and lungs work harder over time.

Overview: what atrial septal defects symptoms can feel like

Atrial septal defects symptoms often include shortness of breath, tiredness, a fluttering or racing heartbeat, and lower exercise tolerance, but many people have no symptoms at all. An atrial septal defect, or ASD, is an opening in the wall between the heart’s two upper chambers, allowing blood to pass from the left side to the right side more than it should.

This extra blood flow can increase the workload on the right side of the heart and send more blood to the lungs. When the opening is small, the heart may cope well and the defect may only be found during a routine exam. When the opening is larger, symptoms may appear in childhood or much later in adulthood.

Unlike some other heart conditions, an ASD may be subtle for years. Symptoms tend to reflect how much the defect affects blood flow rather than simply whether the opening is present. That is why two people with the same diagnosis may feel very different.

ASD is a type of congenital heart defect, meaning it is present at birth. It may occur on its own or alongside other structural heart problems, and understanding the pattern of symptoms can help guide timely evaluation and treatment.

Common symptoms in children and adults

Many infants and children with an atrial septal defect do not appear unwell. Small ASDs may cause no obvious problems. When symptoms do occur in childhood, they can include getting tired easily during feeding or play, slower growth in some cases, shortness of breath with activity, and more frequent respiratory infections than expected.

In teenagers and adults, atrial septal defects symptoms may become more noticeable as years of extra blood flow affect the heart and lungs. People may report breathlessness during walking or exercise, unusual fatigue, reduced stamina, awareness of the heartbeat, or occasional dizziness. Some also notice swelling in the legs or feet if heart strain becomes more advanced.

Heart rhythm disturbances can also be part of the picture, especially in adults. These may feel like pounding, skipped beats, or a fluttering sensation in the chest. Some people first seek care because of an irregular rhythm rather than because they knew they had a structural heart problem.

• Shortness of breath, especially on exertion
• Fatigue or reduced exercise tolerance
• Palpitations or irregular heartbeat
• Frequent lung or chest infections in some children
• Poor weight gain or tiring with feeds in infants
• Swelling of the legs or ankles in more advanced cases

Why symptoms happen: causes, types, and risk factors

An atrial septal defect is usually caused by incomplete formation of the septum, the wall between the atria, during fetal development. It is not caused by anything a person does after birth. In many cases, no single reason is identified, although genetics and certain maternal health or environmental factors may play a role in some pregnancies.

Symptoms happen because oxygen-rich blood from the left atrium moves across the opening into the right atrium. This increases the amount of blood traveling through the right heart and into the lungs. Over time, a large or moderate defect can enlarge the right side of the heart and raise pressure in the lung circulation.

There are several ASD types, including secundum ASD, primum ASD, sinus venosus ASD, and coronary sinus defects. Secundum ASD is the most common. The exact type matters because it influences whether the defect can be monitored, closed with a catheter-based device, or treated with surgery.

Related conditions may exist alongside ASD, including other congenital heart abnormalities, valve problems, or rhythm disorders. In some patients, doctors may also evaluate for congenital heart disease more broadly, especially if symptoms, family history, or imaging suggest additional structural changes.

Related conditions and possible complications over time

Atrial septal defects symptoms can overlap with many other conditions that cause breathlessness or fatigue, such as anemia, asthma, deconditioning, thyroid disorders, or other heart diseases. This is one reason an ASD may be missed or discovered later than expected, particularly when symptoms are mild and gradual.

If a significant ASD is left untreated, the long-term effects can include enlargement of the right atrium and right ventricle, abnormal heart rhythms, and increased pressure in the lung arteries. Some people may develop heart failure symptoms later in life. The risk depends on the size and type of defect and how the heart responds over time.

Stroke can occur in certain situations if a blood clot crosses the opening and travels into the body’s arterial circulation, although this is not the most common presentation. Doctors may think about this possibility when a person has had an unexplained stroke or transient neurologic symptoms.

Conditions linked to pressure changes in the lungs, such as pulmonary hypertension, may become relevant in longstanding cases. Because rhythm problems can also be associated with structural heart changes, some patients are assessed for arrhythmia when palpitations or irregular heartbeats are part of the symptom pattern.

How doctors diagnose an atrial septal defect

Diagnosis usually begins with a medical history and physical examination. A clinician may hear a heart murmur or other characteristic heart sounds, but not every ASD causes obvious exam findings. The pattern of symptoms, age at presentation, and any signs of right heart strain help guide the next steps.

The main test used to confirm an ASD is echocardiography, an ultrasound of the heart. This shows the structure of the septum, estimates the size and type of the opening, and helps assess whether the right side of the heart is enlarged. In some cases, transesophageal echocardiography gives more detailed images, especially when planning closure.

Additional tests may include an electrocardiogram to look for rhythm issues, a chest X-ray to check heart size and lung blood flow, and cardiac MRI or CT when anatomy needs further clarification. Some patients also have exercise testing or cardiac catheterization, particularly if there is concern about lung pressures or if treatment planning is complex.

Because symptoms can resemble many other conditions, careful evaluation matters. A person with persistent breathlessness, exercise intolerance, or palpitations may be referred to a cardiologist for a full assessment, even if earlier symptoms seemed mild or intermittent.

Treatment options and what influences the decision

Treatment depends on the type of ASD, the size of the opening, symptoms, and whether the heart shows signs of overload. Very small defects may only need periodic follow-up. Larger defects, or those causing right heart enlargement, symptoms, or complications, are more likely to need closure.

When anatomy is suitable, closure may be performed through a catheter-based procedure that places a device across the opening without open-heart surgery. In other cases, surgical repair is the best option, especially for certain ASD types or when there are associated structural issues that also need correction. General treatment planning may involve interventional cardiology or cardiovascular surgery depending on the defect.

Medicines do not close the defect itself, but they may help manage symptoms or related problems such as fluid retention or rhythm disturbances. If a person has developed an irregular heartbeat, treatment may also involve evaluation in electrophysiology to better understand and manage the rhythm issue.

Follow-up remains important even after closure, because doctors may continue to monitor heart rhythm, exercise tolerance, and heart chamber size. Near the end of the care pathway, some international patients choose centers such as Acibadem International, where multidisciplinary specialists in JCI-accredited hospitals diagnose and treat congenital and adult structural heart conditions.

Prevention, self-care, and living with an ASD

Because an atrial septal defect is usually present from birth, there is no guaranteed way to prevent it after a child is born. However, early recognition can help prevent long-term strain on the heart and lungs. Regular follow-up is especially important for anyone already diagnosed with an ASD, even if they feel well.

Self-care focuses on heart health and symptom awareness. People are often advised to attend scheduled cardiology visits, take prescribed medicines as directed, and discuss any new symptoms promptly. Good overall habits such as not smoking, staying physically active within a doctor’s guidance, managing blood pressure, and maintaining a balanced diet support cardiovascular health.

Exercise recommendations vary. Many people with a small or repaired ASD can remain active, but those with larger defects, pulmonary hypertension, or rhythm problems may need individualized advice. A cardiologist can explain which activities are reasonable and when a change in exercise tolerance should be evaluated.

Pregnancy planning may also deserve discussion, especially for people with unrepaired ASD, pulmonary pressure problems, or prior rhythm issues. Preconception counseling with a cardiologist can help clarify risks and coordinate safe monitoring when needed.

When to seek medical care

Medical care is appropriate if atrial septal defects symptoms are persistent, unexplained, or getting worse. Breathlessness with usual activity, unusual fatigue, palpitations, or poor exercise tolerance deserve evaluation, especially if there is a known heart murmur, a family history of congenital heart disease, or symptoms that have gradually progressed over time.

More urgent assessment is important for chest pain, fainting, sudden severe shortness of breath, bluish discoloration of the lips or skin, or a rapid irregular heartbeat that does not settle. These symptoms do not always mean an ASD is the cause, but they should not be ignored.

Parents should arrange pediatric review if a baby tires during feeds, breathes fast, has poor weight gain, or has frequent chest infections. In older children, reduced stamina compared with peers can also be a useful clue.

Anyone with a previously diagnosed ASD should seek follow-up if symptoms change after years of stability. Timely review can help determine whether monitoring is still enough or whether closure or another treatment should now be considered.

Frequently asked questions

Can atrial septal defects cause no symptoms?

Yes. Many people with a small atrial septal defect have no symptoms and only learn about it during a routine exam or heart imaging for another reason. Symptoms are more likely when the defect is larger or has affected the heart over many years.

What are the most common atrial septal defects symptoms in adults?

The most common symptoms in adults are shortness of breath with activity, fatigue, reduced exercise tolerance, and palpitations. Some adults also develop swelling in the legs or notice irregular heartbeats as the right side of the heart becomes strained.

At what age do ASD symptoms usually appear?

Symptoms can appear at any age, depending on the size and type of the defect. Some children show signs early, while others remain symptom-free until adulthood, when long-term extra blood flow begins to affect heart function.

Is an atrial septal defect the same as a ventricular septal defect?

No. An atrial septal defect is an opening between the upper chambers of the heart, while a ventricular septal defect is between the lower chambers. Both are congenital heart defects, but they differ in location, blood flow effects, and treatment approach.

Can an atrial septal defect cause palpitations?

Yes. Palpitations can occur, especially in adults, because long-standing changes in the heart’s upper chambers may increase the risk of abnormal rhythms. If palpitations are frequent, prolonged, or associated with dizziness, medical evaluation is important.

Do all atrial septal defects need treatment?

No. Very small defects may only need observation and periodic follow-up. Treatment is considered when the defect is large enough to strain the heart, causes symptoms, or increases the risk of complications.

References

• American Heart Association
• Centers for Disease Control and Prevention
• National Heart, Lung, and Blood Institute
• European Society of Cardiology
• Mayo Clinic

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.