Atrial Septal Defect (ASD)
A hole in the wall between the heart's upper chambers
Quick Facts
- Type: Congenital heart defect
- Location: Wall between the two upper chambers (atria)
- Often found: Childhood checkups or adulthood
- Treatment: Monitoring, catheter closure, or surgery
Overview
An atrial septal defect (ASD) is a hole in the septum, the muscular wall that separates the heart's two upper chambers (the atria). It is a type of congenital heart defect, meaning it is present from birth. The hole allows oxygen-rich blood to flow from the left atrium into the right atrium, sending extra blood back to the lungs.
Small defects may cause no problems and sometimes close on their own in early childhood. Larger or untreated defects can, over many years, strain the heart and lungs. Many people with an ASD live normally, and effective treatments are available when closure is needed.
Symptoms
Many children with an ASD have no symptoms, and the defect may not be noticed until adulthood. When symptoms do appear, they often develop gradually.
- Shortness of breath, especially with activity
- Tiredness or reduced stamina
- A heart murmur heard during an exam
- Frequent respiratory or lung infections in children
- Heart palpitations or an irregular heartbeat, often later in life
- Swelling in the legs, feet, or abdomen in advanced cases
Symptoms of a large untreated ASD tend to emerge in adulthood as the heart works harder over time.
Causes
An atrial septal defect forms during fetal development when the wall between the upper chambers does not close completely. The exact reason is often unknown, but several factors contribute.
- Genetic factors: ASDs can run in families and may occur with certain genetic syndromes.
- Conditions during pregnancy: Some infections, medications, alcohol, or other exposures during pregnancy increase the risk of heart defects.
A small opening called a patent foramen ovale is a normal part of fetal circulation and is different from a true ASD, although the two are sometimes confused.
Risk Factors
- A family history of congenital heart defects
- Certain genetic conditions, such as Down syndrome
- Maternal infections such as rubella during pregnancy
- Use of certain medications, alcohol, or tobacco during pregnancy
- Maternal diabetes that is not well controlled
Diagnosis
An ASD is often first suspected when a heart murmur is heard. Tests confirm the diagnosis and assess its size and effects.
- Echocardiogram: An ultrasound of the heart that is the main test, showing the defect and blood flow through it.
- Electrocardiogram (ECG): Records the heart's electrical activity and rhythm.
- Chest X-ray: Shows the size of the heart and the state of the lungs.
- Cardiac MRI or CT: Used in some cases for detailed images of the heart and blood flow.
- Transesophageal echocardiogram: A specialized ultrasound from behind the heart can give clearer views when planning closure.
Treatment
Treatment depends on the size of the defect and its effect on the heart.
- Watchful waiting: Small defects that cause no problems may simply be monitored, as some close on their own in childhood.
- Catheter closure: Many suitable ASDs are closed with a device guided through a blood vessel, without open surgery.
- Surgery: Open-heart surgery may be used to patch larger defects or those not suited to a catheter device.
- Medications: May be used to manage symptoms such as irregular heart rhythms, though they do not close the hole.
Closing a significant ASD before lasting damage occurs generally leads to excellent long-term outcomes. Over many years, a large untreated defect can lead to complications such as an enlarged right side of the heart, irregular heart rhythms (especially atrial fibrillation), and raised pressure in the lung arteries, known as pulmonary hypertension. Closing the defect at the right time helps prevent these problems. After a catheter or surgical closure, people are usually monitored for a period and may take medication for a short time to prevent clots forming on the device. Most people return to normal activity, and many children who have an ASD closed grow up with no lasting effects on their daily lives.
When to See a Doctor
See a doctor if you or your child has shortness of breath, unusual tiredness, palpitations, or a known heart murmur that has not been evaluated. Seek prompt medical care for:
- Sudden or worsening shortness of breath
- Fainting or near-fainting
- An irregular or racing heartbeat
- New swelling in the legs, feet, or abdomen
Frequently Asked Questions
Can an atrial septal defect close on its own?
Some small atrial septal defects close by themselves during early childhood. Larger defects usually do not close on their own and may need a catheter device or surgery. Regular follow-up helps decide whether and when treatment is needed.
Is an ASD dangerous?
Small defects often cause no harm, but a larger untreated ASD can strain the heart and lungs over many years and lead to problems such as irregular heart rhythms or high pressure in the lung arteries. Closing a significant defect prevents these complications.
How is an atrial septal defect repaired?
Many ASDs are closed using a small device delivered through a catheter in a blood vessel, avoiding open surgery. Larger or unusually shaped defects may need open-heart surgery to place a patch. Your cardiologist recommends the best option.
Can adults have an undiagnosed ASD?
Yes. Because small ASDs may cause no symptoms, some people are not diagnosed until adulthood, often after a murmur is heard or symptoms like breathlessness or palpitations appear. An echocardiogram confirms the diagnosis.
Can someone with an ASD live a normal life?
Many people with a small or successfully treated ASD live full, normal lives. Outcomes are generally very good when significant defects are closed before lasting damage occurs. Ongoing cardiology follow-up is recommended in many cases.
References
- Centers for Disease Control and Prevention (CDC). Atrial Septal Defect.
- Mayo Clinic. Atrial septal defect (ASD).
- MedlinePlus, U.S. National Library of Medicine. Atrial septal defect.