Atrial septal defect

Alternative names

Atrial septal defect is an abnormality of the upper chambers of the heart (atria) where the wall between the right and left atria does not close completely. This defect is present at birth (congenital).

Causes, incidence, and risk factors

Atrial septal defect (ASD) is a congenital heart defect. In fetal circulation there is normally an opening between the two atria (the upper chambers of the heart) to allow blood to bypass the lungs. This opening usually closes about the time the baby is born. If the ASD is persistent, blood continues to flow from the left to the right atria. This is called a shunt.

ASD is present in 4 out of 100,000 people. When the person has no other congenital defect, symptoms may be absent, particularly in children. Symptoms usually have manifested by age 30. Individuals with ASD are at an increased risk for developing a number of complications including:

  • infective endocarditis (a bacterial infection of the heart)  
  • heart failure  
  • an abnormally fast heart rhythm known as Atrial Fibrillation


  • frequent respiratory infections in children  
  • difficulty breathing (dyspnea)  
  • Shortness of breath with activity  
  • sensation of feeling the heart beat (palpitations)

Note: People with small-to moderate-sized defects may show no symptoms at all, or not until middle age or later.

Signs and tests

There may be a palpable pulsation of the pulmonary artery in the chest. Examination with a stethoscope (auscultation) of the heart usually reveals abnormal heart sounds. There may be a murmur caused by the increased blood flow across the pulmonic valve, and signs of heart failure. If the shunt is large, increased blood flow across the tricuspid valve (between the right atrium and ventricle) may be responsible for an additional murmur.

Tests that may be performed in the diagnosis of ASD include:

  • A Chest x-ray  
  • An echocardiography (ultrasound of the heart) or a contrast echocardiography  
  • A color Doppler/ study of the heart  
  • Transesophageal echocardiography (TEE)  
  • A Cardiac catheterization  
  • A Coronary angiography (for patients over 35 years old)  
  • An MRI of chest (sometimes)

An ECG may show Atrial Fibrillation, right atrial enlargement, or a pattern of delayed electrical conduction in the heart.


ASD may not require treatment if there are few or no symptoms, or if the defect is small. Surgical closure of the defect is recommended if the atrial septal defect is large or if symptoms occur.

Recently, a new procedure has been developed to close the defect without surgery. This involves the introduction of a closure device into the heart through wires or catheters.

A tiny incision is made in the groin to introduce the catheters. They are then advanced into the heart where the closure devise is placed across the ASD and the defect is closed.

This procedure is relatively new and may not be applicable to all patients. Prophylactic (preventive) antibiotics should be given prior to dental procedures to reduce the risk of developing infective endocarditis.

Expectations (prognosis)
With a small-to-moderate atrial septal defect, a person may live a normal life span without symptoms. Larger defects may cause disability by middle age because of increased blood flow and shunting of blood back into the pulmonary circulation.


Calling your health care provider
Call your health care provider if symptoms indicating an atrial septal defect develop.

There is no known way to prevent the defect, but some of the complications can be prevented with early detection.

Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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