Atrial Septal Defect (ASD)

In the United States, approximately 1 in every 1,859 infants is born with a congenital heart defect - an atrial septal defect (ASD). Girls develop ASDs twice as often as boys. This heart malformation occurs during fetal development. A hole is present in the wall (the septum) between the two atriums (the two chambers at the top of your heart). This hole allows blood to flow in the wrong direction in the heart and can lead to heart and lung complications.

Key takeaways:
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    An atrial septal defect is a hole in the wall between the two upper chambers of the heart that does not close properly after birth.
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    Usually, the hole closes by itself after a while, but if not, it has the potential to cause complications in the heart and lungs.
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    Symptoms depend on the size of the hole. If the hole does not close on its own and the symptoms are severe enough, surgery may be necessary to treat it.
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    Surgery generally has an excellent outcome, and the patient can usually live a full and productive life.

How does the heart work?

Your heart has four separate chambers, two on top called the atria (plural for atrium), and two on the bottom called the ventricles.

In a normal, healthy heart, blood circulates through the heart and body in a semi-figure-8 pattern.

Blood is pumped from the right atrium (singular of atria) into the right ventricle, through the pulmonary artery, and into the lungs where it picks up oxygen.

The oxygen-rich blood is then pumped into the left atrium, through the left ventricle, into the aortic artery, and then into the rest of the body.

The oxygen-depleted blood then re-enters the right atrium to begin the circuit again.

How does an ASD change the way the heart functions?

As a baby's heart develops, several openings are present in the walls between the heart chambers. For the most part, pressure changes in the heart cause these holes to close soon after the baby is born.

If the opening between the top two chambers, the atria, does not close completely, the hole left is called an atrial septal defect.

ASDs vary in size, and the hole may eventually close on its own, or it may need surgery to repair.

The hole allows blood to flow from one atrium to the other, and excess blood leaks into the right atrium. This extra blood puts added pressure on the pulmonary artery and increases the amount of blood flowing into the lungs, which increases the workload of the heart and lungs which can lead to heart and lung damage.

What are the symptoms?

Many babies do not experience any symptoms; however, the symptoms that do appear vary in severity based on how big the hole in the heart measures.

Symptoms may begin at any age, including adulthood:

  • Arrhythmias (irregular heartbeat).
  • Cough.
  • Cyanosis (bluish skin or nails).
  • Difficulty breathing.
  • Dizziness.
  • Fainting.
  • Fatigue.
  • Frequent lung or respiratory infections.
  • Heart murmur.
  • Poor appetite.
  • Shortness of breath - especially with activity or exercise.
  • Skipped heartbeats, or heart palpitations.
  • Stroke.
  • Swelling in the legs, feet, or abdomen.
  • Tiring quickly during feedings in infants.

How is an ASD diagnosed?

A doctor can diagnose an ASD using screening tests before a baby is born.

Sometimes an atrial septal defect is not found until later in life; in that case, a heart murmur is usually the first symptom.

To confirm a suspected ASD diagnosis, your doctor may want you to have an echocardiogram: an ultrasound showing images of the heart, its function, and blood flow.

How is an ASD treated?

Your doctor will determine treatment based upon the size of the hole, the severity of the symptoms, the presence of other heart defects, and the age at which the ASD is diagnosed.

At first, your doctor may only want to monitor you for a while to determine if the hole will close without medical intervention.

Your child’s pediatrician may order medications to treat symptoms. If medication does not help, or the hole is big enough to cause problems later in life, the pediatrician may recommend an intervention to close the ASD. Depending on the severity of the defect, a heart catheterization or open-heart surgery can be used to repair the ASD.

In addition, your doctor may prescribe medications to help your child’s heart pump more effectively; these may include blood thinners, diuretics, or medication designed to help your heart pump more efficiently.

Complications of an ASD

If left untreated, an atrial septal defect can lead to complications such as:

  • Blood clots that travel to other parts of the body.
  • Right-sided heart failure.
  • Heart arrhythmias.
  • Increased chances of pneumonia, bronchitis, or other respiratory infections.
  • Pulmonary hypertension (high blood pressure in the arteries in the lungs).
  • Stroke.
  • Early death.

Causes of an ASD

An atrial septal defect develops while a baby grows in the uterus and is present at birth. In most children, the cause is not known for sure.

Sometimes the defect is genetic: A hereditary condition passed down from a parent or grandparent or the health conditions and/or lifestyle choices of the mother during pregnancy can increase the risk of a baby having an ASD:

  • Use of certain medications, such as medications used to treat mood disorders and anti-seizure medications.
  • German measles (rubella) infection during the first few months of pregnancy.
  • Illegal drug use.
  • Tobacco use.
  • Alcohol use.
  • Diabetes.
  • Lupus.

ASD and pregnancy

If you have been diagnosed with an ASD and are pregnant or plan to become pregnant, talk with your doctor. An ASD can lead to a high-risk pregnancy. Your healthcare provider may want to fix the defect before you become pregnant.

Outlook for an ASD

If surgery is needed, the outlook is usually excellent. Most of the time, patients do not even need medication after surgery.


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