An atrial septal defect (ASD) is a congenital heart defect, a problem with the heart’s structure that is present at birth. Put most simply, an ASD is an abnormal hole in the wall that divides the atria—the two upper chambers of the heart. Some ASDs are small and close on their own. Others are larger and, if left untreated, may cause damage to the heart over time.  

While ASDs are often identified in the first year of life, they also have been diagnosed later in childhood and, occasionally, even in adulthood. Whenever the condition is discovered, ASDs need to be closely monitored and appropriately treated.  

Atrial septal defects in childhood tend to not cause significant symptoms and are picked up most commonly at a murmur examination, or when an echocardiogram is done for another reason, says Yale Medicine pediatric cardiologist Dina Ferdman, MD.

“The majority of these defects, when found in early infancy, resolve completely on their own. Small ASDs do not require any treatment and may be monitored every couple of years,” she says. “But those that do persist into early childhood—and remain large—can be closed with a procedure in the pediatric cardiac catheterization laboratory, avoiding the need for cardiac surgery.” 

The heart is made up of four chambers. Babies are born with a small opening in the wall (called the septum) located between the two upper chambers; it allows the developing fetus to draw oxygen directly from the placenta. Once a baby is born and breathing on its own, however, blood needs to travel through the lungs to draw oxygen before it’s pumped out to the body. The opening closes naturally in most people within the first weeks or months of life.

But, if there is a larger opening in the wall, which is called an ASD it may not close completely. The Centers for Disease Control and Prevention (CDC) estimates that ASDs occur in 1 of 1,859 births in the United States each year. It’s not always clear why a baby develops an ASD, though there is some indication that genetics may sometimes play a role. 

An atrial septal defect may cause no symptoms at all, especially if it is small. A doctor may be able to detect a larger hole when he or she listens to the heart with a stethoscope, and hears a swishing noise called a heart murmur or another sound that isn’t normal. In children, other ASD symptoms may include:

• Fatigue
• Poor appetite and growth
• Shortness of breath
• Frequent lung or respiratory infections

If an ASD is discovered in adulthood, the symptoms may be different. They may include:

• Skipped heartbeats, palpitations or other abnormal heart sounds
• Shortness of breath, especially during exercise
• Susceptibility to bronchitis and pneumonia
• Fatigue
• Swelling in the abdomen, feet, or legs

Large ASDs that aren’t treated can lead to such serious issues as arrhythmia and stroke.

A pediatric cardiologist who suspects an atrial septal defect may order imaging tests, such as an electrocardiogram to better understand the heart’s rhythm, and an echocardiogram to get a picture of the heart, its blood flow, and surrounding organs.

Some small atrial septal defects don’t affect the lungs and patients do fine without treatment. But a large one may need to be plugged using either synthetic material or a patch made from the lining outside the heart, called the pericardium. This treatment is usually done in early childhood (even if the hole is large, but not causing symptoms). Recovery from the procedure is quick, sometimes requiring no more than one night in the hospital.

A doctor may be able to close the hole with an interventional catheterization procedure that involves inserting a thin, flexible tube through the leg and up through a blood vessel to the heart, where a plug is positioned to close the hole.

Some patients may need open heart surgery, either because they have one or more other heart problems or due to an ASD that is in an unusual position, making it difficult to fix with catheterization. Open heart surgery requires general anesthesia. 

The surgeon will also use a heart-lung machine to take over the patient’s respiratory function; this allows the heart to be still so that the surgeon can make an incision in the chest, and go inside and close the hole, either by placing a synthetic patch or sewing it shut.

While patients will have to restrict some activities after treatment, most go on to live healthy, active lives. Though it is important to adhere to doctor’s instruction on follow-up cardiac care, most people don’t need medicines beyond about six months, or additional surgeries or other treatments. Most women who have had proper care for an ASD can expect to have a safe pregnancy.

Yale Medicine Pediatric Cardiology has extensive experience caring for infants and children with atrial septal defects and other congenital heart problems. Our Adult Congenital Heart Program extends that care to adults of all ages, providing many patients with seamless care from birth to adulthood. Our specialists take a team approach to each case, bringing together pediatric cardiac surgeons, pediatric cardiologists, neonatologists, intensivists, child life specialists, and other experts.

Our specialists are members of the comprehensive Children’s Heart Center at the Yale New Haven Children’s Hospital, and other Yale Medicine specialty clinics and programs.