ASD — Atrial Septal Defect — is a hole in the wall between the two upper chambers of the heart, and it is one of the most common congenital heart defects found in children and adults. The good news: most ASDs can be closed completely, either with a simple catheter-based device or with surgery — and the outcomes are excellent.

Dr. Ved Prakash, Director of CTVS at Yatharth Super Speciality Hospitals, Greater Noida, explains what ASD means, when treatment is needed, and what the safest, most effective option is for your child or family member.

What Is ASD — Atrial Septal Defect?

The heart is divided into four chambers — two upper chambers (atria) and two lower chambers (ventricles). The wall dividing the two atria is called the atrial septum. In a normal heart, this wall is completely sealed and blood cannot cross from one side to the other at this level.

An ASD is a hole in this wall. Blood flows through the hole from the left atrium (where oxygenated blood returns from the lungs) to the right atrium (where de-oxygenated blood collects before going to the lungs) — because the pressure on the left side is slightly higher. This means the right side of the heart receives more blood than it should, and more blood is sent to the lungs with each heartbeat.

Over years, this extra volume causes the right side of the heart to enlarge and, in severe cases, raises the blood pressure in the lungs (pulmonary hypertension) — which can become irreversible if the ASD is left unclosed for too long.

Types of ASD

• Ostium secundum ASD: The most common type — a hole in the central part of the atrial septum. Most suitable for catheter-based device closure.
• Ostium primum ASD: Located in the lower part of the septum, near the heart valves. Almost always requires surgical repair — device closure is not possible.
• Sinus venosus ASD: Near the junction of the atria and the large veins entering the heart. Requires surgical repair.
• Patent Foramen Ovale (PFO): A small flap-like opening that all foetuses have and that normally closes after birth. A PFO is not a true ASD but can cause problems in some adults — particularly cryptogenic stroke.

ASD Symptoms — What to Watch For

Small ASDs often cause no symptoms at all — particularly in children, who compensate remarkably well. Larger ASDs may cause:

• Frequent respiratory infections in infancy — bronchitis or pneumonia more often than peers
• Reduced exercise tolerance in older children — tiring faster than classmates
• Breathlessness on exertion — particularly as the child grows and demands on the heart increase
• Heart palpitations — particularly in adults with undiagnosed ASD, often from atrial fibrillation
• Stroke in younger adults — a blood clot can cross from the right to the left side through a large ASD and travel to the brain

Many ASDs are first discovered when a routine examination reveals a heart murmur — or when an echocardiogram is performed for another reason. Some are diagnosed in adulthood when the patient presents with atrial fibrillation or breathlessness and the cause is traced back to a previously unknown ASD.

How Is ASD Diagnosed?

• Echocardiogram: The primary investigation — shows the location and size of the ASD, the direction of blood flow through it, and the degree of right heart enlargement
• Bubble echocardiogram: Agitated saline injected into a vein — bubbles crossing from right to left confirms an opening
• Cardiac MRI: Useful for precise assessment of the shunt volume and right heart dimensions when planning intervention
• ECG: May show right heart enlargement patterns

When Does an ASD Need Treatment?

• If the ASD is significant enough to cause right heart enlargement on echocardiogram — even without symptoms
• If symptoms are present (breathlessness, reduced exercise tolerance, palpitations)
• If pulmonary blood flow is significantly elevated (Qp:Qs ratio greater than 1.5:1)
• If the ASD is causing atrial fibrillation

Small ASDs (less than 5mm) in infants often close spontaneously by age 2–3. Larger ASDs do not close on their own and require intervention — ideally before school age if possible, though the procedure is safe at any age.

Can ASD Be Closed Without Open-Heart Surgery?

Yes — for the right anatomy. This is one of the most common questions parents ask.

Device Closure (Catheter-Based — No Surgery)

For ostium secundum ASDs of appropriate size and position, a device is delivered through a vein in the leg (femoral vein) using a catheter. The device — which looks like a small double-disc — is positioned across the hole and deployed to plug it. The procedure is performed under general anaesthesia and guided by echocardiography. The child typically goes home the next day.

Suitable for: Centrally located ostium secundum ASDs with adequate tissue rims around the defect. Confirmed by echocardiogram during assessment.

Surgical ASD Closure (Open-Heart Surgery)

For primum ASDs, sinus venosus ASDs, and secundum ASDs that are too large or in an unsuitable position for device closure, surgical repair is performed. A patch of pericardium (the heart’s own lining) or a synthetic patch is sewn over the hole. The results are permanent and excellent — success rates exceed 99%.

Frequently Asked Questions — ASD Heart Defect

What is ASD and is it dangerous?

ASD (Atrial Septal Defect) is a hole between the two upper chambers of the heart. Small ASDs may be harmless and close on their own. Larger ASDs, if left untreated for years, can cause right heart enlargement, pulmonary hypertension, atrial fibrillation, and stroke. Treatment before these complications develop produces excellent long-term outcomes.

Will a small ASD close on its own?

Small ostium secundum ASDs (less than 5mm) often close spontaneously by age 2–3. ASDs detected at birth are monitored with serial echocardiograms. Larger ASDs and primum or sinus venosus ASDs do not close on their own and require intervention.

At what age should an ASD be closed?

Ideally before school age (4–6 years) if the ASD is significant — this prevents long-term right heart changes and the child recovers quickly. However, the procedure is safe at any age. Adults with undiagnosed ASDs can and do have successful closure well into middle age.

How long does ASD device closure take?

The catheter procedure takes approximately 45–60 minutes under general anaesthesia. The child is typically observed overnight and discharged the next morning, returning to school within a week.

Is ASD surgery painful for a child?

All ASD procedures are performed under general anaesthesia — the child feels nothing during the procedure. Post-procedure discomfort for device closure is minimal. After surgical closure, pain is managed effectively with medications throughout the hospital stay and settles significantly within 1–2 weeks.

Get a Clear Assessment for Your Child’s ASD

If your child has been diagnosed with an ASD — or if you want a second opinion on whether device closure or surgery is more appropriate — consult Dr. Ved Prakash for paediatric heart surgery in Delhi NCR. For more on congenital heart conditions, read our complete guide on congenital heart defects in children.

Online consultation available — share your child’s echocardiogram via WhatsApp at +91-9355255106 for an assessment before your in-person visit.