Atrial septal defect (ASD): causes and symptoms

Reviewed by Judy Haluka

The atrial septal defect (ASD) is a congenital cardiac disorder in which a hole in the wall (septum) divides the upper chambers (atria) of the heart. The hole can differ in size and may close on its own or need surgery. The atrial septal defect is a congenital cardiac defect that exists at the time of birth.

There is always an opening between the upper heart chambers of a baby at the time of birth called the foramen ovale. This opening allows fetal circulation to bypass the lungs until birth. This opening is no longer required and usually closes or becomes very small within some time after birth. However, if the opening is larger than normal, it may not close after birth.

If these openings do not close, a hole is left in the atria, and is called an atrial septal defect. The hole increases blood flow to the lungs and may damage the blood vessels in the lungs later on. Damage caused to the blood vessels in the lungs can lead to cardiac problems in adulthood, including pulmonary hypertension in the lungs, an arrhythmia (abnormal heartbeat), stroke, and cardiac arrest.

Atrial septal defects are among the most common types of congenital heart defects. These defects are often diagnosed in adulthood and found more commonly in females than males.

Causes

There are no known causes of atrial septal defects among most babies. Some babies have cardiac conditions due to genetic conditions. These types of cardiac defects may be caused due to a combination of genes and other risk factors, such as environmental conditions, food, and drugs.

Types

Atrial septal defects types include:

• Secundum - This is the most commonly found type of atrial septal defect. It develops in the center of the wall between the upper heart chambers (atrial septum).
• Primum - This type of atrial septal defect occurs in the lower part of the atrial septum. It can also occur with other congenital cardiac defects.
• Sinus venosus - This type of atrial septal defect rarely occurs in the upper part of the wall separating the heart chambers. It can occur along with other heart structure changes present at the time of birth.
• Coronary sinus - In this rare condition of the atrial septal defect, part of the wall between the coronary sinus, which is the vital part of the vein system of the heart, and the left upper heart chamber (left atrium) is not present.

Risk factors

The atrial septal defect occurs when the baby’s heart is in the process of developing during pregnancy. Some health conditions or medicines during pregnancy can increase a baby’s risk of ASD or other congenital cardiac defects.

The risk factors can include:

• Diabetes
• Lupus
• Alcohol or tobacco use
• Rubella (German measles) infection in the first few months of pregnancy
• Illegal drug use, such as cocaine
• Use of certain drugs, including some anti-seizure medicines for treating mood problems
• Some types of congenital cardiac disorders are inherited.

If the patient’s family history includes a congenital cardiac disorder, such as an atrial septal defect, screening by a genetic counselor can help ascertain the risk of cardiac disorders in future babies.

Complications

A minor atrial septal defect doesn’t cause any concern, as these defects often close during infancy on their own.

Larger atrial septal defects can result in serious complications, which can include:

• Stroke
• Early death
• Right-sided heart failure
• Irregular heartbeats
• Hypertension in the lungs and arteries (pulmonary hypertension)

Pulmonary high blood pressure can lead to permanent lung damage. This complication, called Eisenmenger syndrome, typically develops over time and can occur in untreated large atrial septal defects.

Prevention

As the exact cause of the atrial septal defect is unknown, prevention is currently impossible. However, getting proper prenatal care is important. Those planning to have a baby with an atrial septal defect should work closely with their health care provider.

Their visits should target:

• Discussing present health conditions and medications under use. Certain health conditions, such as diabetes or lupus, are monitored during the entire pregnancy. Your health care provider can also suggest adjusting some medications before pregnancy.
• Reviewing your family medical history. If you have a family medical history of congenital cardiac disorders or other genetic conditions, consult with a genetic advisor to determine your risk factors.
• Prenatal screening, like testing for immunity to German measles (rubella). Rubella in the mother can lead to some types of congenital cardiac disorders in the baby. Ensure to get properly vaccinated before pregnancy if you’re not immune.

Treatment

Treatment for an atrial septal defect (ASD) depends on the size of the hole, the patient’s age, the number and severity of symptoms, and the presence of other cardiac conditions. Sometimes certain medicines are prescribed to help treat symptoms. Sometimes the hole is repaired via surgery. There are no specific medications that can help in repairing the hole.

If a baby is diagnosed with an atrial septal defect, the health care provider may monitor it for a certain period of time to see if the hole closes on its own. During this period, the health care provider will treat symptoms with medications. To prevent cardiac problems later in life, the health care provider can recommend the atrial septal defect be treated for a baby. Closure can also be recommended for an adult with severe or many symptoms. Closure of the hole may be done during heart catheterization or open-heart surgery. After completing these procedures, follow-up care will depend on the patient’s age, the size of the hole, and whether the patient has any other birth disorders.

Works cited

• Centers for Disease Control and Prevention. Congenital Heart Defects- Facts about atrial septal defects. January 24, 2022. Accessed August 30, 2022. https://www.cdc.gov/heart-defects/about/atrial-septal-defect.html
• Cleveland Clinic. Atrial septal defect. July 15, 2022. Accessed August 30, 2022. https://my.clevelandclinic.org/health/diseases/11622-atrial-septal-defect-asd
• Mayo Clinic. Atrial septal defect (ASD). March 1, 2022. Accessed August 30, 2022. https://www.mayoclinic.org/diseases-conditions/atrial-septal-defect/symptoms-causes/syc-20369715