Atrial Septal Defect (ASD)

What is Atrial Septal Defect?

In an atrial septal defect, an opening between the left atrium and the right atrium allows blood to shunt between the chambers. Because atrial pressure normally is slightly higher in the left atrium than in the right, blood typically shunts from left to right. The pressure difference may force large amounts of blood through the defect during diastole. If the hole is more than '1/8" (1 cm) in diameter, the atria actas a single chamber.

Most infants with an atrial septal defect have no significant left-to-right shunt and no symptoms because during diastole, blood flows toward the ventricular chamber (usually the right). which has thinner. more compliant walls.

An atrial septal defect is found in about 10% of children who have congenital heart disease and who have survived past their first birthday. The disorder is almost twice as common in females as in males and has a strong familial tendency.

Causes of Atrial Septal Defect

The cause of an atrial septal defect is unknown.In this disorder, left-to-right shunt results in right ventricular volume overload, which affects the right atrum. right ventricle, and pulmonary arteries. Eventually, the right atrium enlarges and the right ventricle dilates to accommodate the increased blood volurre.

Signs & Symptoms of Atrial Septal Defect

ASD signs and symptoms depend on its size and the amount of blood flows that flows abnormally across the defect. Symptoms may include:

• Shortness of breath with activity
• Frequent respiratory infections in children
• Irregularities in heart rhythm (dysrhythmias), especially atrial dysrhythmias
• Sensation of feeling the heart beat (palpitations)
• Difficulty breathing (dyspnea)

Diagnostic Tests

Chest X-rays - An X-ray image helps your doctor see the condition of your heart and lungs. An X-ray may identify conditions other than a heart defect that may explain your signs or symptoms.

Electrocardiography results may be normal but usually show right axis deviation, a prolonged PR interval, varying degrees of right bundle-branch block, right ventricular hypertrophy, atrial fibrillation (particularly in severe cases after age 30) and, in ostium primum, left axis deviation.

Echocardiography - In echocardiography, sound waves produce a video image of the heart. It allows your doctor to see your heart's chambers and measure their pumping strength. This test also checks heart valves and looks for any signs of heart defects.

Cardiac catheterization can be used to confirm an atrial septal defect by demonstrating that right atrial blood is more oxygenated than superior vena cava blood, which indicates a left-to-right shunt. Catheterization also can be used to determine the degree of shunting and pulmonary vascular disease. Pulmonary artery systolic pressures are usually positive. Dye injection shows the defect's size and location, the location of pulmonary venous drainage, and atrioventricular valve competence. Cardiac catheterization is performed only when the patient's doctor strongly suspects an atrial septal defect but the patient has unusual symptoms.

Treatment

Atrial septal defects often correct themselves without medical treatments by the age of two. If this dose not happen, surgery is done by sewing the hole closed, or by sewing a patch of Dacron material or a piece of the sac that surrounds the heart (the pericardium), over the opening.

Some patients can have the defect fixed by having an clam-shaped plug placed over the opening. This plug is a man-made device that is put in place through a catheter inserted into the heart.

Prevention Tips

In most cases, atrial septal defects can't be prevented. If you have a family history of heart defects or other genetic disorders, consider talking with a genetic counselor before getting pregnant.