Pediatric Heart Disease Atrial Septal Defect

Atrial septal defect (ASD) is a common congenital heart defect, which is a heart defect present from birth. In healthy hearts, the heart is divided into four chambers:

  • the left atrium
  • the left ventricle
  • the right atrium
  • the right ventricle.

A wall called a septum separates each section of the heart. Atrial septal defect describes a condition in which a hole exists in the septum dividing the two atria.

How Common is ASD?

As a relatively common pediatric defect, atrial septal defect occurs in about 6 percent to 8 percent of all congenital heart defect cases. Although the exact causes of atrial septal defect are unknown, gender appears to be a risk factor. Girls are more likely than boys to be born with ASD.

Another risk factor that contributes to atrial septal defect is complications during the first trimester of pregnancy. The heart grows from a single tube into four separate chambers within weeks of conception. Problems during this time, such as genetic defects, maternal illness and chromosomal defects can trigger development of atrial septal defect in the fetus.

Atrial Septal Defect Complications and Side Effects

Many cases of atrial septal defect are self-correcting. In fact, 90 percent of ASDs require no treatment because they close as the child grows older.

However, larger ASDs can cause health problems. In a normal functioning heart, oxygen-deficient blood enters the right atrium while blood replenished with oxygen (from the lungs) enters the left atrium. Then the oxygen-deficient blood flows into the right ventricle where the blood is pumped up to the lungs to get oxygenated.

In patients with ASD, oxygenated blood from the left atrium instead passes through the atrial septal defect into the right atrium. In the right atrium, the oxygenated blood mixes with oxygen-depleted blood and is sent back to the lungs.

The result is that the heart must work harder to deliver enough oxygen to the body. Overexertion may result in an enlarged heart and congestive heart failure.

ASD Symptoms

A small atrial septal defect will usually have no symptoms and, as noted above, may close without medical intervention. However, a larger ASD can cause congestive heart failure symptoms. Signs of a severe atrial septal defect include:

  • delayed growth
  • fatigue
  • lung problems
  • recurring lung infections
  • shortness of breath
  • small appetite.

Diagnosing Atrial Septal Defect

As most atrial septal defects cause few or no symptoms, the condition can be difficult to detect until progressive congestive heart failure causes damage to the heart and lungs. Most cases of ASD are diagnosed when doctors hear unusual heart sounds, or heart murmurs, during routine physical examinations.

Heart murmurs associated with atrial septal defect have a characteristic sound. Although it’s logical to assume that the murmur is produced by the septal defect itself, an ASD heart murmur actually comes from the pulmonary valve. The murmur results from excessive volumes of blood passing through the valve.

Once a heart murmur is discovered, diagnostic testing, usually through an echocardiology, confirms or rules out the presence of an atrial septal defect. By using sound waves to construct images of the heart, an echocardiogram can effectively detect the septal defect, the size of the septum holes and any enlargement of the heart.

Atrial Septal Defect Treatment

Between 80 percent and 90 percent of atrial septal defects close without medical intervention, the majority within the first 18 months of life. If an ASD remains open after the child is 3 years old, the defect is unlikely to repair itself and may require surgical correction.

Until recently, the only treatment for atrial septal defect was open-heart surgery. During surgery, the septum is stitched closed. If the hole is too big to stitch closed, a patch is used to seal the hole.

Because open-heart surgery is such an invasive procedure, in 2001, the U.S. Food and Drug Administration approved a device called the Amplatzer Septal Occluder as a less invasive alternative to open-heart surgery.

The Amplatzer Septal Occluder is delivered to the heart through cardiac catheterization. A small tube, or catheter, is inserted into an artery in the groin or arm. The catheter is then threaded through the arteries to the heart, where it positions the Amplatzer Septal Occluder over the ASD, sealing the hole.

If left untreated, ASD can cause serious health problems in later life. Long-term strain on the heart and lungs can result in:

  • atrial arrhythmias
  • congestive heart failure
  • pulmonary hypertension
  • stroke.

ASD Treatment Follow-up

Although children usually respond well to atrial septal defect surgery, complications can develop. Post-surgical complications associated with ASD treatments include:

  • breathing difficulties
  • cyanosis (blue discoloration of the lips and fingernails due to poor blood-oxygen levels)
  • difficulty feeding
  • fevers
  • low energy levels
  • oozing from the incision scar
  • pain at the incision scar
  • poor appetite
  • poor weight gain
  • weight loss.


American Heart Association (2007). Atrial septal defect (ASD). Retrieved September 4, 2007, from the AHA Web site:

Cincinnati Children’s Hospital Medical Center (2006). Atrial septal defect (ASD). Retrieved September 4, 2007, from the Cincinnati Children’s Hospital Medical Center Web site:

Nemours Foundation (2007). Atrial Septal Defect. Retrieved September 4, 2007, from the KidsHealth for Parents Web site:

U.S. National Library of Medicine (2007). Atrial septal defect. Retrieved September 4, 2007, from the Medlineplus Web site: