Atrial Septal Defect (ASD)

What is it?

An atrial septal defect (or ASD for short) is a hole in the heart – specifically in the atrial septum (the dividing wall between the right and left atria of the heart).

The atria are the upper pumping chambers of the heart.

An ASD can be large or small, and some may require no treatment. Pressure in the left side of the heart is much higher than the right and an ASD will allow blood from the left atrium to pass to the right atrium. If the ASD is large, it will result in the right hand side of your baby’s heart being overloaded with blood and the heart has to pump more blood than normal to the right atrium of the lungs.

The bigger the hole, the more blood that goes through the hole, and the harder the heart has to work. This can lead to heart and lung damage.

How can it be spotted?

During pregnancy there is normally an opening separating the two upper chambers of the heart (atria). This is called the foramen Ovale. This allows blood to flow from the right atria to the left atria into the left ventricle then aorta. This opening closes shortly after birth. If this fails to close then a hole is left called an atrial septal defect. This might be detected on ultrasound depending on the size of the hole and its location.

After birth, an ASD are often identified due to the sound of the extra blood moving through the right side of the heart and the pulmonary artery, heard as a heart murmur.

Babies with large defects may be breathless and struggle to feed and gain weight. Those with smaller atrial septal defect may only show mild symptoms of having a heart condition, or may not have any symptoms at all. Frequent chest infections can be a sign that the oxygenation process is not working efficiently due to extra blood flow to the lungs.

To confirm the presence of an ASD, an echocardiogram (or echo) is usually conducted. This is an ultrasound scan of the heart – which can show the pattern of blood flow through the ASD, and determine how large the opening is, as well as much blood is passing through it.

How can it be treated?

Small ASDs often do not require treatment and will usually close naturally over a period of time.

Larger ASDs will need surgery to prevent permanent damage to the lungs and, ultimately, heart failure. The hole is closed using open heart surgery or through a catheter intervention.

For most babies, the heart surgery is low risk but it does depend on the general wellbeing of the child. The length of time in hospital will usually be about a week, depending on how well the child is otherwise.

The catheter intervention uses a catheter (tube), which is passed through a vein into the heart. The ASD is then sealed by inserting a device through it and withdrawing the catheter. When the catheter is withdrawn, the device opens on both sides of the hole to close it.

This procedure is not regarded as surgery and they would probably spend only two or three days in hospital afterwards.

General advice/info for the future

Your cardiologist will advise you about any restrictions on activity that you should be aware of as your baby grows up, but they should be able to live a full and active life, with occasional check-ups.

If your baby had open heart surgery, they will have a scar down the middle of the chest, and there will be small scars where drain tubes were used, but these will fade over time.

Harriett was born with an atrial septal defect. Read her story here.