Can an ASD or PFO Close Naturally Without Treatment?

Yes, some small “holes in the heart” found in babies—specifically small atrial septal defects (ASDs) and patent foramen ovales (PFOs)—can close completely on their own without surgery ^[1][2]. However, this depends heavily on the person’s age and the size of the hole. For older children and adults, these defects generally do not close on their own. The good news is that many PFOs never need to be closed at all, even if they remain open for life ^[3].

ASDs in Babies and Children

If your baby was recently diagnosed with a secundum atrial septal defect (the most common type of ASD), there is a good chance it may close or shrink on its own as they grow ^[1]. The likelihood of natural closure comes down to size:

• Small ASDs (under 4 to 5 millimeters): Have a high chance of closing spontaneously during early childhood ^[1].
• Medium ASDs (5 to 8 millimeters): Have a variable chance of closing or shrinking. They require careful monitoring to see what the body will do naturally ^[1].
• Moderate to Large ASDs (over 8 millimeters): Are much less likely to close without medical intervention ^[1][2].

Because many of these smaller defects close naturally, pediatric cardiologists typically recommend a “watch and wait” approach for infants ^[2]. Your child will likely have regular echocardiograms (ultrasounds of the heart) to track the size of the hole and ensure it is not affecting the size or function of the heart chambers over time ^[1].

ASDs in Adults

If you are an older child or adult diagnosed with an ASD, it is highly unlikely that the hole will close on its own ^[1]. In adults, an untreated ASD can lead to long-term complications over time. Because blood constantly flows through the defect from the left side of the heart to the right, it can cause the right side of the heart to become enlarged. This extra workload can eventually lead to symptoms like reduced exercise capacity, fatigue, or abnormal heart rhythms ^[4][5].

For these reasons, if an adult ASD is large enough to cause significant extra blood flow and enlarge the right side of the heart, doctors often recommend closing it—even if you currently have no symptoms—to prevent future heart damage ^[4]. Very small ASDs that do not cause the heart to enlarge may simply be monitored rather than closed.

What About PFOs?

A patent foramen ovale (PFO) is a slightly different type of opening. It is a normal flap-like opening in the heart wall that exists in every fetus before birth, allowing blood to bypass the lungs. In most people, it seals shut shortly after birth. But in about 1 in 4 people (25% of the population), it remains partially open into adulthood.

If a PFO has not closed by adulthood, it will not close naturally later in life. However, unlike ASDs, an open PFO rarely causes any problems and does not typically enlarge the heart. If you have a PFO and no symptoms, it generally does not need to be closed ^[3]. Doctors typically only recommend closing a PFO if a patient has experienced a specific type of unexplained stroke (called a cryptogenic stroke) and the PFO is believed to be the pathway that allowed a blood clot to travel to the brain ^[6][7].

Summary of Medical Approaches

When a hole in the heart needs to be closed, it is often done using a minimally invasive catheter procedure (placing a small device through a vein in the leg) rather than open-heart surgery ^[8].

• Small ASDs in infants: Watchful waiting with regular ultrasounds ^[1].
• Large ASDs or ASDs in older patients: Often repaired with a catheter-based device or surgery to protect long-term heart health ^[4].
• Asymptomatic PFOs: Monitored but usually left alone; no treatment is necessary for most people ^[3].
• PFOs linked to unexplained strokes: May be closed with a specialized catheter device to prevent future strokes ^[6][7].