Overview

An atrial septal defect (ASD) is a hole in the heart wall between the two upper chambers. The condition is present at birth. Small defects may never cause a difficulty and may be found incidentally. It is also possible that small atrial septal defects may close on their own during infancy or early childhood.

Large and long-standing atrial septal defects can damage the heart and lungs. An adult who has had an undetected atrial septal defect for decades may have a shortened lifespan from heart failure or high blood pressure that affects the arteries in the lungs (pulmonary hypertension). Surgery may be necessary to repair atrial septal defects to prevent complications.

Symptoms

Many babies born with atrial septal defects do not have associated signs or symptoms. In adults, signs or symptoms may begin around the age of 30, but in some cases, signs and symptoms may not occur until decades later.

Atrial septal defect signs and symptoms may include:

• Shortness of breath, especially when exercising
• Fatigue
• Swelling of legs, feet or abdomen
• Heart palpitations (increased heart beats that can be felt by the patient) or skipped beats
• A stroke
• Heart murmur(a whooshing sound that can be heard through a stethoscope)

Causes

Why do heart defects develop?

Doctors know that heart defects present at birth arise from errors early in the foetal heart's development, but there is often no clear cause. Genetics and environmental factors may play a role.

How does the heart work with an atrial septal defect?

An atrial septal defect allows freshly oxygenated blood to flow from the left upper chamber of the heart into the right upper chamber of the heart. There, it mixes with deoxygenated blood and is pumped to the lungs, even though it is already refreshed with oxygen.

If the atrial septal defect is large, this extra blood volume can overfill the lungs and overwork the right side of the heart. If not treated, the right side of the heart eventually enlarges and weakens. If this process continues, blood pressure in the lungs may increase as well, leading to pulmonary hypertension.

Atrial septal defects can be of several types, including:

• Secundum: This is the most common type of ASD and occurs in the middle of the wall between the atria.
• Primum: This defect occurs in the lower part of the atrial septum and may occur with other congenital heart problems.
• Sinus venosus: This rare defect usually occurs in the upper part of the atrial septum.
• Coronary sinus: In this rare defect, a part of the wall between the coronary sinus — which is part of the vein system of the heart — and the left atrium is missing.

Risk factors

It is not known why atrial septal defects occur but congenital heart defects appear to run in families and sometimes occur with other genetic problems such as Down’s syndrome.

Some conditions that an individual has or that occur during pregnancy may increase the risk of having a baby with a heart defect, including:

• Rubella infection: Becoming infected with Rubella (German measles) during the first few months of pregnancy can increase the risk of foetal heart defects.
• Use of certain medications, tobacco, alcohol or drugs such as cocaine during pregnancy can harm the developing foetus.
• Diabetes or lupus: If the mother of the newborn baby has diabetes or lupus she may be more likely to have a baby with a heart defect.
• Obesity: Mother being extremely overweight may play a role in increasing the risk of having a baby with a birth defect.
• Phenylketonuria (PKU): If the mother has PKU and is not following a PKU meal plan, she is more likely to have a baby with a heart defect.

Complications

A small atrial septal defect may never cause any problems. Small atrial septal defects often close during infancy.

Larger defects can cause serious problems, including:

• Right-sided heart failure.
• Heart rhythm abnormalities (arrhythmias).
• Increased risk of a stroke.
• Shortened lifespan.

Less common serious complications may include:

• Pulmonary hypertension: If a large atrial septal defect goes untreated, increased blood flow to the lungs increases the blood pressure in the lung arteries.
• Eisenmenger syndrome: Pulmonary hypertension can cause permanent lung damage. This complication usually called Eisenmenger syndrome normally develops over many years and occurs uncommonly in people with large atrial septal defects.

Atrial septal defect and pregnancy

Most women with an atrial septal defect can tolerate pregnancy without any problems. However having a larger defect or having complications such as heart failure, arrhythmias or pulmonary hypertension can increase the risk of complications during pregnancy. Doctors strongly advise women with Eisenmenger syndrome not to become pregnant because it may be dangerous to their lives.

The risk of congenital heart disease is higher for children of parents with congenital heart disease whether it is present in the father or the mother. Anyone with a congenital heart defect,(repaired or not), who is considering starting a family should carefully discuss it beforehand with a doctor. Some medications may need to be stopped or adjusted before a woman plans to conceive because they can cause serious problems for a developing foetus.

Prevention

In most cases, atrial septal defects cannot be prevented. If a woman is planning to conceive, she needs to schedule a preconception visit with a doctor. This visit should include:

• Getting tested for immunity to Rubella: If a woman is not immune, consult the doctor about getting vaccinated.
• Going over one’s current health conditions and medications: An individual needs to carefully monitor certain health problems during pregnancy. The doctor may also recommend adjusting or stopping certain medications before one gets pregnant.
• Reviewing family medical history: If one has a family history of heart defects or other genetic disorders, she must consider talking with a genetic counsellor to determine what the risk might be before getting pregnant.

Diagnosis

A doctor may first suspect an atrial septal defect or other heart defects during a regular check-up if he or she hears a heart murmur while using a stethoscope.

If the doctor suspects the child has a heart defect he may request one or more of the following tests:

• Echocardiogram: This is the most commonly used test to diagnose an atrial septal defect. During an echocardiogram, sound waves are used to produce a video image of the heart. It allows the doctor to see the heart's chambers and measure their pumping strength.
  This test checks heart valves and looks for any signs of heart defects. Doctors may use this test to evaluate the condition and determine the treatment plan. Some atrial septal defects can be found during an echocardiogram done for another reason.
• Chest X-ray: An X-ray image helps the doctor to see the condition of the heart and lungs. An X-ray may identify conditions other than a heart defect that may explain signs or symptoms.
• Electrocardiogram (ECG): This test records the electrical activity of the heart and helps identify heart rhythm problems.
• Cardiac catheterisation: In this test, a thin flexible tube is inserted into a blood vessel at the groin or arm and guided towards the heart. Through catheterisation, doctors can diagnose congenital heart defects and also test how well the heart is pumping and check the function of the heart valves. Using catheterisation, the blood pressure in the lungs can also be measured.
• Magnetic resonance imaging (MRI): A MRI is a technique that uses a magnetic field and radio waves to create 3-D images of the heart and other organs and tissues within the body. A doctor may request an MRI if echocardiography cannot definitively diagnose an atrial septal defect.
• Computerized tomography (CT) scan: A CT scan uses a series of X-rays to create detailed images of the heart. A CT scan may be used to diagnose an atrial septal defect if echocardiography has not diagnosed an atrial septal defect.

Treatment

Many atrial septal defects close on their own during childhood. From those that don't close, the small atrial septal defects do not cause any problems and may not require any treatment. But many persistent atrial septal defects eventually require surgery to be corrected.

Surgery

Many doctors recommend repairing an atrial septal defect diagnosed during childhood to prevent complications as an adult. Doctors may recommend surgery to repair medium-to large-sized atrial septal defects. However, surgery is not recommended if one has severe pulmonary hypertension because it might make the condition worse.

For adults and children, surgery involves sewing close or patching the abnormal opening between the atria. Doctors will evaluate the condition and determine which procedure is most appropriate. Atrial septal defects can be repaired using two methods:

• Cardiac catheterisation: In this procedure, doctors insert a thin tube into a blood vessel in the groin and guide it to the heart using imaging techniques. Through the catheter, doctors insert a mesh patch or plug into place to close the hole. The heart tissue grows around the mesh, permanently sealing the hole.
• Open-heart surgery: This type of surgery is done under general anaesthesia and requires the use of a heart-lung machine. Through an incision in the chest, a surgeon uses patches to close the hole. This procedure is the preferred treatment for certain types of atrial septal defects (primum, sinus venosus and coronary sinus) and these types of atrial defects can only be repaired through open-heart surgery. This procedure may also be conducted using small incisions for some types of atrial septal defects.

Follow-Up Care

Follow-up care depends on the type of defect and whether other defects are present. Repeated echocardiograms are done after hospital discharge, one year later and then as recommended by the patient or the cardiologist / cardiothoracic surgeon. For simple atrial septal defects closed during childhood, only occasional follow-up care is generally needed.

Adults who have had atrial septal defect repair need to be monitored throughout life to check for complications, such as

• Pulmonary hypertension
• Arrhythmias
• Heart failure or valve problems
• Follow-up exams are typically done on a yearly basis