An atrial septal defect is a congenital heart issue. According to the Centers for Disease Control and Prevention (CDC), it develops in about 1 in 1,859 babies in the United States.

An atrial septal defect is a hole in the wall inside the heart known as the septum, which divides the left and right atrium. According to 2018 research, this condition is the third most common type of heart irregularity seen in newborns.

Small holes often repair themselves. But doctors usually recommend surgically closing medium or large defects even if they aren’t causing symptoms. This can help prevent problems or complications later in life.

It is important to know how the heart works to understand an atrial septal defect.

an illustration of an unaffected heart vs a heart with an atrial septal defect
Illustration by Sophia Smith

Your heart is made up of four chambers. The left and right chambers are the two chambers that are the most important. Blood moves through the chambers.

  1. Blood from your body enters your right atrium.
  2. It goes from your right atrium to your right ventricle, which pumps it to your lungs.
  3. Your left atrium is where the blood returns from your lungs.
  4. It goes from your left atrium to your left ventricle, which pumps it to the rest of your body.

This article will look at the different types of atrial septal defects, how they are diagnosed and treated, and what the outlook is for this type of heart condition.

Doctors divide atrial septal defects into four primary categories, depending on where the hole is:

  • Ostium secundum defect. This is when the hole develops in the middle part of your septum. This is the most common type. According to a 2015 review, it makes up about 75 percent of cases.
  • Ostium primum defect. In this instance, the hole develops in the lower part of your septum. This type of atrial septal defect makes up about 15 to 20 percent of cases.
  • Sinus venosus defect. With this type, the hole develops in the upper part of your septum. A 2019 case study suggests sinus venosus has a lower rate of spontaneous closure than other types.
  • Coronary sinus defect. This is when the hole develops in the wall that separates your left atrium from your coronary sinus. Coronary sinus defects are the rarest type.

An atrial septal defect is a congenital defect, meaning that it’s present from birth. According to the CDC, the cause of most atrial septal defects isn’t known.

Every baby is born with an opening between the upper chambers of the heart. This hole keeps blood away from the lungs while a baby is in the womb. The opening is no longer needed once a baby is born and closes within several weeks to months, according to the American Heart Association (AHA). If the hole is larger than usual it may not close after birth.

Some heart defects may be caused by genes. Exposure to certain chemicals in the womb may contribute to these changes.

Ostium primum defects commonly occur in people with Down syndrome or Ellis-van Creveld syndrome.

The symptoms of an atrial septal defect are often mild and usually aren’t noticeable in infancy. The CDC says some babies with severe defects may have symptoms such as:

  • There are frequent infections.
  • fatigue when feeding
  • stroke

The most common sign in childhood, and often the only sign, is a heart murmur. Children with severe defects, particularly with ostium primum defects, may experience symptoms such as:

A 2011 study found that up to 33.8 percent of adults with unrepaired atrial septal defects have heart palpations.

Early diagnosis and screening is important and usually leads to favorable outcomes, according to 2020 research. Older studies have found that 90 percent of people with untreated large atrial septal defects don’t live to their 60th birthdays.

Atrial septal defects are not usually diagnosed until adulthood. Small defects might not cause any noticeable symptoms.

A doctor can detect a murmur and listen to your heart through a stethoscope.

If a doctor hears a murmur, they may order a special ultrasound of your heart called an echocardiogram. This type of diagnostic test uses sound waves to produce live images of your heart. This allows your doctor to see the inside of your heart, how well it’s working, and how blood is flowing through it.

Another diagnostic tool your doctor may order is a transesophageal echocardiogram. With this procedure, a thin probe will be passed down your throat into your esophagus, which is close to the upper chambers of your heart. The probe will then use high frequency sound waves to produce detailed images of the structures inside your heart.

The seriousness of an atrial septal defect depends on the situation.

  • “The hole’s size.”
  • How much blood is being carried?
  • Which direction the blood is moving in?

The left side of your heart pumps blood to your body, while the right side pumps blood to your lungs. A hole between your atria can cause blood to flow back into your heart.

The blood vessels that supply your lungs can be enlarged by this build up of blood. This pressure can damage your lungs and heart.

Small holes less than 5 millimeters (about 0.2 inches) can heal by themselves within 1 year after birth. Defects over 1 centimeter (about 0.4 inches) are most likely to require treatment to avoid complications later in life.

About half of septal defects resolve by themselves without treatment, according to 2017 research. The other half require treatment either with a procedure called cardiac catheterization and percutaneous closure or with open heart surgery.

Watchful waiting

Doctors recommend waiting to see if the hole will close on its own when a young child is diagnosed with an atrial septal defect. The doctor may prescribe drugs to treat symptoms.

Cardiac catheterization

Cardiac catheterization is a procedure that can be used to treat heart defects. During this procedure, your cardiologist inserts a tube through a blood vessel in your neck. They put it to your heart and plug the hole.

This procedure is less risky than open heart surgery, but only for ostium Secundum defects.

Open heart surgery

Early in childhood, open heart surgery is done. If the hole is large or not ostium defect, surgery may be needed.

The AHA says small unrepaired holes rarely cause problems later in life. They typically don’t require you to limit physical activity or change your lifestyle.

People with larger defects are more likely to need treatment. Your cardiologist may recommend lifestyle changes while you are recovering from treatment.

Once you are fully recovered, you can return to your usual activities, but you have to have a checkup with your doctor. You can live an active life once the hole is closed.

Atrial septal defects are one of the most common congenital heart defects. There is a hole in the heart. The hole can heal on its own. There are larger holes that may need treatment.

Atrial septal defects are not known until late childhood or adulthood. If you receive a diagnosis of an Aortic Septal Defect, your doctor can give you more information about the type of defect and the treatment that is right for you.