Atrial Septal Defect

What is an atrial septal defect?

An atrial septal defect is a hole in the heart that forms an abnormal connection between 2 of the heart's chambers. It is a birth defect. The size of the hole can be very small or it may be more than an inch in diameter.

There are 4 chambers in the human heart. The upper 2 are called atria. The atrial septum separates the right atrium from the left atrium. The right atrium receives blood from the veins of the body, and the left atrium receives blood from the lungs.

When there is a hole in the atrial septum, the higher blood pressure in the left atrium pushes blood into the right atrium. This adds to the normal amount of blood coming from the body to the heart. This added volume increases both the workload of the right ventricle (the pumping chamber to the lungs) and the flow of blood in the lungs.

How does it occur?

As you may imagine, a baby's development from a tiny egg requires very complex changes. Just what goes wrong is unknown. A gene defect or other influences may prevent the heart tissues from developing properly. An atrial septal defect usually does not otherwise prevent the heart or the baby from developing normally, and the defect does not appear to be inherited.

What are the symptoms?

Unless the defect is very large or associated with some other cardiac defect, most babies and children have few or no symptoms. In fact, many people may live their entire lives with small atrial septal defects and be unaware of it. Some people will not develop symptoms but may need surgery when they are middle-aged. Larger defects may cause symptoms including shortness of breath, faster breathing rate, or decreased growth. The extra blood flow through the lungs may cause an increase in blood pressure in the lungs. Heart failure may develop, with cough and swelling of the legs or ankles. Occasionally, the added strain on the heart results in irregular heart rhythms (atrial fibrillation).

How is it diagnosed?

If the defect is small, diagnosis is difficult and a heart echocardiogram may be the only clue to its presence. A heart echocardiogram bounces sound waves off the heart to create a detailed picture of the heart and its structures. This is a painless procedure that can be done in your doctor's office.

Sometimes cardiac catheterization may be needed. In this procedure, a very thin tube is passed through a vein into the heart. The pressure in the chambers of the heart is measured and blood samples can be taken. This helps diagnose a defect, and can tell how big the defect is.

In larger defects there is an increased flow of blood through the heart that creates a heart murmur, which can be heard with a stethoscope. The increased blood flow may also cause heart enlargement noted on a chest X-ray or on an electrocardiogram. An electrocardiogram is a test that measures the electrical activity of your heart.

How is it treated?

People who develop symptoms as from the defect should have a procedure to close the hole. If there are no symptoms, treatment depends on how much blood flows through the defect. If it is a very small amount, there is no benefit from having the defect closed. If it is a moderate or large amount, you are better off having the defect closed. In general, it is best to have the closure at a younger age before damage has been done to the heart or lungs. Your doctor will make a recommendation based on your symptoms and the size of the defect.

If the hole is small enough, the surgeon may sew it shut. The surgeon may patch the defect using a small piece of tissue from the sac surrounding the heart (the pericardium). Sometimes the defect can be fixed by pushing a flexible plastic "umbrella" through a leg vein and attaching it over the hole. This form of treatment does not require chest surgery.

When should I call the doctor?

If you have a known atrial septal defect and no symptoms, try to live as normally as possible.

Have regular checkups. Call your doctor if you notice a sudden increase in shortness of breath, you awake at night short of breath, or you become aware of an irregular heartbeat.