What are Atrial Septal Defects

TL;DR: An Atrial Septal Defect (ASD) is a congenital heart condition characterized by an opening in the wall (septum) that separates the heart's two upper chambers, the atria. This hole allows oxygen-rich blood to leak from the left atrium back into the right atrium, potentially causing strain on the heart and lungs over time.

What are the different types of Atrial Septal Defects?

There are four primary classifications of an Atrial Septal Defect, categorized by the location and nature of the opening:

• Ostium secundum ASD: The most common type, occurring in the middle of the atrial septum.


• Ostium primum ASD: Located in the lower part of the septum, often associated with other valve abnormalities.


• Sinus venosus ASD: Found near the junction of the superior or inferior vena cava.


• Coronary sinus ASD: A rare form where the opening is near the coronary sinus.

How common are Atrial Septal Defects?

Atrial Septal Defects are among the most frequently diagnosed congenital heart anomalies. They account for approximately 5% to 10% of all congenital heart disease cases. Research indicates an incidence of roughly 1 in every 1,500 live births. At DiseaseMaps.org, 47 community members have shared their experiences with this condition, highlighting that while it is often detected in childhood, many individuals are not diagnosed until adulthood.

What causes an Atrial Septal Defect?

During fetal development, the heart forms as a single tube that eventually divides into chambers. An Atrial Septal Defect occurs when the tissue that separates the right and left atria fails to close properly before birth. While the exact cause remains unknown in most cases, a combination of genetic factors and environmental influences during pregnancy is believed to play a role.

How does an Atrial Septal Defect affect the body?

In a healthy heart, the septum prevents blood mixing. With an Atrial Septal Defect, oxygenated blood flows from the left atrium back into the right, causing the right side of the heart to pump extra blood to the lungs. If left untreated, this volume overload can lead to pulmonary hypertension, arrhythmias, or heart failure. Unlike a Patent Foramen Ovale (PFO), which is a flap-like opening that remains from fetal circulation, an Atrial Septal Defect involves a true deficiency of septal tissue.

Next steps

• Consult a pediatric or adult congenital cardiologist for an echocardiogram to assess the size and impact of the defect.


• Monitor for symptoms such as exercise intolerance, shortness of breath, or frequent respiratory infections.


• Join the DiseaseMaps.org community to connect with other patients and caregivers.

Medical disclaimer: This information is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment.

References

• NIH Genetic and Rare Diseases (GARD) Information Center - Atrial Septal Defect


• Orphanet: Congenital atrial septal defect


• American Heart Association: Atrial Septal Defect (ASD)


• OMIM (Online Mendelian Inheritance in Man): Atrial Septal Defect entry