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Dr. Alessandro Giardini
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An atrial septal defect: a hole in the wall between the two upper chambers of the heart: is one of the most common congenital heart findings. It is also one of the most frequently misunderstood. Many parents receive the diagnosis and immediately expect surgery. In reality, the management of an ASD is considerably gentler than that for most children. Most are monitored while they close on their own, or closed using a catheter technique without open-heart surgery.
For a full background on what an ASD is, the different types, and how it is diagnosed, see the ASD overview page on this website.
Not all ASDs need to be closed. Small defects, particularly those found in the first months of life, may close spontaneously as the heart grows and matures. Spontaneous closure is most likely to occur in the first two to three years of life. And the chance of natural closure reduces significantly after the age of two. After that, it rarely happens.
For children with small ASDs that show signs of getting smaller, the approach is careful monitoring with periodic echocardiograms and no intervention. Some of these children eventually have no detectable defect at all. Others retain a small opening that is so haemodynamically insignificant that it needs nothing more than occasional reassurance. In either case, the child leads a completely normal life.
Closure is generally considered when the ASD is large enough to be causing the right side of the heart to work harder than it should. The ASD allows oxygen-rich blood from the left atrium to cross into the right atrium. This means the right heart and lungs receive more blood than they need, creating a volume load that, over time, can cause the right heart to enlarge. This is the mechanism.
In most children, this does not cause any noticeable symptoms during childhood. Enlargement of the right heart on echocardiogram is often the first sign. And it is this finding, rather than symptoms, that typically prompts the recommendation to close. The conventional timing for closure in a well child with a moderate-to-large ASD is between the ages of three and five, before primary school age. Closing the defect at this stage prevents the right heart enlargement from becoming established and protects the lungs from the effects of long-term excess blood flow. Earlier closure is better.
Occasionally, an infant or toddler with a large ASD will develop symptoms, including breathlessness, poor feeding, or slow weight gain. Closure is brought forward in these cases. Equally, some ASDs are discovered by chance in older children or adults who have no symptoms at all. Late closure is still beneficial and is associated with an excellent outcome. But the earlier a significant ASD is closed, the better the cardiac remodelling that follows.
This is where the ASD story diverges significantly from the VSD story. For most VSDs, surgery is the standard approach. For most ASDs, it is not.
The standard method for closing a secundum ASD, by far the most common type, is transcatheter device closure. A thin catheter is guided through a blood vessel in the groin into the heart. And a small umbrella-shaped occluder device is positioned across the hole. The device expands on both sides of the septum to seal the defect. Over the following months, the heart's own tissue grows over the device, making the closure permanent.
No chest opening is required. No bypass machine is used. The child is under general anaesthetic for the procedure, typically spends one night in hospital. And can usually return to normal daily activities within a week or two. It is a genuinely remarkable procedure. Recovery is dramatically faster than surgical repair, and the outcomes at experienced centres are excellent.
Children who have had a catheter closure are advised to take a low-dose aspirin for six months afterwards while the tissue heals over the device. After that, no ongoing medication is needed.
Not all ASDs are suitable for catheter closure. Defects that are very large, positioned too close to the heart valves, or located in parts of the atrial septum where a device cannot sit safely require surgical repair. Surgery suits these. Sinus venosus ASDs and primum ASDs, for example, are almost always closed surgically. Dr. Giardini will explain which approach is appropriate based on the specific anatomy of the defect. Dr Giardini undertakes the echocardiogram personally so the reasoning behind the recommendation is always clear and is provided at the time of the first appointment.
The outlook after ASD closure in childhood is excellent for the vast majority of children. The right heart typically returns to a normal size within months of the procedure. Children go on to live fully unrestricted, active lives with no ongoing medication and no activity limitations. Competitive sport can usually resume after few months.
Research comparing quality of life in children who have had ASD closure with their healthy peers shows no significant difference. That is a reassuring finding and reflects how well most children do after this procedure. Follow-up is generally straightforward: a check-up and echocardiogram at six months and then annually for a few years, with discharge from routine follow-up once the heart has fully remodelled. Most children do well.
It depends on the size and type of the defect. Small defects have the best chance of spontaneous closure, and this is most likely to occur in the first two years of life. Secundum ASDs, the most common type, can also reduce in size over the first few years, though large ones rarely close entirely without intervention. The echocardiogram findings and the trend over time are the key factors in deciding whether to wait and monitor or to recommend closure. Dr Giardini will discuss the likelihood of natural closure based on your child's specific anatomy.
Catheter closure involves no chest incision, no stopping the heart, and no bypass machine. A device is delivered through a blood vessel in the groin and positioned across the defect. The child is typically home the same day. Open-heart surgery, which is used for defects not suitable for catheter closure, involves a chest incision and a short period on bypass. Recovery takes longer, usually around a 5-7 days in hospital and six to eight weeks for full healing. For most secundum ASDs, catheter closure is the preferred approach because the results are equivalent and the recovery is far gentler.
For a well child with a moderate-to-large ASD and no symptoms, the conventional timing is between three and five years of age. Closing the defect at this stage prevents the right heart from enlarging further and protects the lungs. In some children the process is brought forward because of symptoms or significant right heart enlargement detected earlier. ASDs found incidentally in older children or adolescents are also closed when they are haemodynamically significant, and the outcomes remain very good. There is no single right age; the recommendation is tailored to the individual child.
Most children can go home on the same day after catheter closure and are back to normal daily activities within a week. School and light activity can usually resume quickly, usually within 1 week. Contact sports and swimming are typically avoided for two to four weeks while the access site in the groin heals. Aspirin at a low dose is prescribed for six months to prevent any clot formation around the device while the heart's tissue grows over it. After six months, no ongoing medication is needed and there are no further activity restrictions.
A small ASD that is not causing any strain on the heart can remain safely unaddressed for life. Regular monitoring is still recommended to check for any changes. A moderate-to-large ASD that is left untreated over many years can lead to persistent right heart enlargement, reduced exercise tolerance in adulthood, an increased risk of atrial arrhythmias, and in some cases pulmonary vascular disease. That is worth understanding. These complications take decades to develop, which is why childhood closure is recommended for significant defects: the earlier the repair, the better the long-term outcome. Adults with untreated large ASDs can still benefit from closure, though the cardiac remodelling that follows is less complete than in children.
Author: Dr. Alessandro Giardini, MD, PhD, Consultant Paediatric Cardiologist
Written 30/05/2026