Skip to main content

Atrial Septal Defect (ASD)

An atrial septal defect (ASD) is a hole in the partition (septum) between the two upper chambers (collecting chambers) of the heart called atria.

When small defects are found by chance, they might never cause symptoms, and some of them close during infancy or early childhood.

If the hole is larger, is allows significant amount of blood from the left collecting chamber (LA) to cross the septum and to flow to the lungs.

A large, long-standing (years) atrial septal defect can damage your heart and lungs.

Surgery or device closure might be necessary to close the defect to prevent complications.


Many babies born with atrial septal defects have minimal or no symptoms. Later on in life some symptoms can start to be more evident:

  • Shortness of breath, especially when exercising
  • Fatigue
  • Recurrent chest infections
  • Heart palpitations or skipped beats
  • Stroke

Types of Atrial Septal Defects

There are several types of atrial septal defects, including:

  • Secundum. This is the most common type of ASD and occurs in the middle of the wall between the LA and RA in the atrial septum.
  • Primum. This defect occurs in the lower part of the atrial septum very close to the Tricuspid valve. It is most invariably associated with an abnormal Mitral Valve
  • Sinus venosus. Is a rare defect which usually occurs in the upper part of the atrial septum and is often associated with other congenital heart problems.
  • Coronary sinus. A rare defect where the partition between the coronary sinus — which is part of the vein drainage system of the heart — and the left atrium is missing.


Small atrial septal defects often close during infancy. Larger defects, if left untreated for many years, can cause serious problems, including:

  • Heart failure
  • Heart rhythm abnormalitie
  • Risk of a stroke

Less common serious complications may include:

  • Pulmonary hypertension. If a large atrial septal defect goes untreated, increased blood flow to your lungs increases the blood pressure in the lung arteries (pulmonary hypertension).

Treatment can prevent or help manage many of these complications.


Atrial septal defect and pregnancy

Most women with an atrial septal defect can go through pregnancy without problems related to the defect. However, having a larger defect or having complications such as heart failure, arrhythmias or pulmonary hypertension can increase the risk of complications during pregnancy.

The risk of congenital heart disease is higher for children of parents with congenital heart disease. Anyone with a congenital heart defect, repaired or not, who is considering starting a family should talk to a doctor. The doctor might recommend repair before pregnancy.



Most of the time your general practitioner might hear a murmur while listening to your child’s chest and suspect an atrial septal defect or other heart defect. Your doctor might request for your child to be seen by a heart specialist (paediatric cardiologist) who will examine your child and request one of the following tests:

  • Echocardiogram (Echo). This is the most commonly used test to diagnose an atrial septal defect.
  • Chest X-ray. This helps to ascertain the heart and lungs conditions like an enlarged heart or congested lungs.
  • Electrocardiogram (ECG). This test records the electrical activity of your heart and helps identify heart rhythm problems.
  • Cardiac catheterisation. Through this test doctors can test how your heart is working and measure the blood pressure in your heart and lungs. In some circumstances, when for example the ASD is not too large, the cardiologists could close the defect with a device, using the same catheterisation.
  • Magnetic Resonance Image (MRI). Using this test, the doctors will know some aspects of the function of the diseased heart which are important to choose the appropriate treatment.
  • Computerized Tomography (CT) scan.  A CT scan can be used as a complement to diagnose an atrial septal defect and other congenital heart defects in particular cases and to plan treatment.


Many atrial septal defects close spontaneously during childhood. The very small ASD that don’t close can be left untreated, as insignificant. Those ASD that don't close and are of a significant size will need treatment either with catheter intervention or surgery.

Medical monitoring

Your cardiologist might recommend monitoring your child with annual tests to see if the ASD will get smaller and closes on its own. Monitoring might be needed to allow the child to grow to the adequate size to close the defect


Sometimes medications are recommended to improve physical conditions and to reduce the effects of the ASD on the heart and lungs. In adult patients with a diagnosis of ASD, medications are also prescribed to keep the heartbeat regular or to reduce the risk of blood clots.

Intervention to close ASD

Recommendations are in place to close a medium to large atrial septal defect diagnosed during childhood or adulthood in order to prevent complications.

At present there are two main treatments available:

  • Trans – catheter device closure. Specialist cardiologists (interventionists) using as access one of the groins’ blood vessels, insert a thin catheter into a blood vessel and guide it to the heart using X-rays. Through the catheter, a special mesh or plug is positioned to close the hole. The procedure is used to repair secundum type of atrial septal defects only. 
  • Open-heart surgery. In case of large secundum atrial septal defects, open heart surgery might be required. Surgery is done under general anaesthesia and requires the use of a heart-lung machine. The chest is opened in the midline (breast bone) and surgeons stitch a patch to close the hole.

Postoperative Care

Patients who have the ASD closed by a device usually stay in hospital a couple of days before been sent home.

After surgery, patients are admitted after the operation to the Intensive Care Unit where they spend  at least one day before been transferred to the postoperative ward for a total of 4 to 5 days hospital stay.

Follow-up care

Irrespective of the type of treatment, follow up is arranged within a week of the treatment by the cardiologists, usually after one week following discharge from the hospital. Regular follow ups are arranged annually till the child is grown into adulthood.

Adults who've had atrial septal defect repair need to be monitored throughout life to check for complications, such as pulmonary hypertension, arrhythmias, heart failure or valve problems.


Lifestyle and exercise

  • Exercise. Having an atrial septal defect usually doesn't restrict from exercise activities. If you have experienced arrhythmias, heart failure or pulmonary hypertension, your cardiologist might suggest avoiding some activities or exercises. If you have an unrepaired defect, you will be advised to refrain from practicing activities like scuba diving and high-altitude climbing.
  • Preventing infection. Some heart defects and the repair can create a new surface lining to areas of your heart making it more prone to infection (infective endocarditis). Atrial septal defects aren't associated with higher rate of infective endocarditis, but your doctor might recommend preventive antibiotics whenever you have dental work done.