Atrial septal defect

Description, Causes and Risk Factors:

Abbreviation: ASD.

The heart is divided into four separate chambers. The upper chambers, or atria, are divided by a wall called the atrial septum. An ASD is a hole in that septum. ASD is a congenital (present at birth) heart defect. As the fetus is growing, something occurs to affect heart development during the first eight weeks of pregnancy, resulting in an ASD.

The heart is forming during the first eight weeks of fetal development. It begins as a hollow tube, then partitions within the tube develop that eventually become the septa (or walls) dividing the right side of the heart from the left. Atrial septal defects occur when the partitioning process does not occur completely, leaving an opening in the atrial septum.

Some congenital heart defects may have a genetic link, either occurring due to a defect in a gene, a chromosome abnormality, or environmental exposure, causing heart problems to occur more often in certain families. Most atrial septal defects occur sporadically (by chance), with no clear reason for their development.

Types most commonly encountered ASDs are,

Ostium secundum atrial septal defect.

• Ostium primum atrial septal defect.

• Sinus venosus atrial septal defect.

• Coronary sinus atrial septal defect.

ASDs can be located in different places on the atrial septum, and they can be different sizes. The symptoms and medical treatment of the defect will depend on those factors. In some rare cases, ASDs are part of more complex types of congenital heart disease.

Symptoms:

Many children have no symptoms and seem healthy. However, if the ASD is large, permitting a large amount of blood to pass through to the right side of the heart, the right atrium, right ventricle, and lungs will become overworked, and symptoms may be noted. The following are the most common symptoms of atrial septal defect.

Child tires easily when playing.

• Fatigue.

• Sweating.

• Rapid breathing.

• Shortness of breath.

• Poor growth.

• Frequent respiratory infections.

Diagnosis:

The following tests are commonly used in diagnosis of ASD,

Chest X-ray - a diagnostic test which uses invisible X-ray beams to produce images of internal tissues, bones, and organs onto film. With an ASD, the heart may be enlarged because the right atrium and ventricle have to handle larger amounts of blood flow than normal. Also, there may be changes that take place in the lungs due to extra blood flow that can be seen on an X-ray.

• Electrocardiogram (ECG or EKG) - a test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias), and detects heart muscle stress.

• Echocardiogram (echo) - a procedure that evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor that produce a moving picture of the heart and heart valves. An echo can show the pattern of blood flow through the atrial septal opening, and determine how large the opening is, as well as how much blood is passing through it.

Treatment:

Specific treatment for ASD will be determined by your child's physician based on:

Your child's age, overall health, and medical history.

• Extent of the disease.

• Your child's tolerance for specific medications, procedures, or therapies.

• Expectations for the course of the disease.

• Your opinion or preference.

In some children, an ASD may close on its own without treatment. With a small atrial septal defect, the rate of spontaneous closure may be as high as 80 percent in the first 18 months of life. An ASD still present by 3 years of age will probably never close on its own and require external approach such as,

Open-Heart Surgery: Although an atrial septal defect may be closed by open-heart surgery, this approach is not as common as it once was now that transcatheter closure devices are readily available. Should open heart surgery be deemed necessary, the surgeon may be able to directly close the hole with sutures or, depending on the size and shape of the hole, may need to close it with a patch. Surgery is very effective and carries a low risk profile.

Transcatheter Device Closure: Depending on the size and the area of the septum involved, many atrial septal defects may be closed by placement of a device during a cardiac catheterization. This device is inserted through a catheter and covers the ASD by attaching to the atrial septum. A catheter is a long thin tube, about the diameter of a piece of spaghetti, which is directed to the heart through the large blood vessels in the groin.

The benefits of being able to close an ASD with a transcatheter device is that it can be put in place without stopping the patient's heart or utilizing cardiopulmonary bypass, it doesn't have the psychological trauma related to open-heart surgery and it doesn't create a scarring across the chest the way open-heart surgery does.

Two FDA-approved devices are currently available in the United States and readily used in the catheterization laboratory. These include the Amplatzer Septal Occluder™ and the Helex Septal Occluder™.

There are risks and complications with these procedures. They include but are not limited to the following,

Infection can occur which may require treatment including antibiotics.

• Bleeding could occur and may require a blood transfusion and/or a return to the operating room.

• Bleeding is more common if you have been taking blood thinning drugs such as warfarin or aspirin.

• Small areas of the lung can collapse, increasing the risk of chest infection. This may need antibiotics and physiotherapy.

• Impaired circulation may occur to a limb or to an organ which may require further treatment.

• Death or brain damage as a result of this procedure is possible.

Specific risks:

Fluid collecting in the sac around the heart.

• Abnormal heart beat. This may need medication to correct or a pacemaker.

• Stroke causing paralysis and long term disability.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.