Quick answer: roughly 1.4 million adults in the United States are living with congenital heart disease, a population that now outnumbers children with the condition thanks to improved pediatric survival. Among adults specifically, the atrial septal defect is the most common congenital lesion, since small defects often go undiagnosed until adulthood. Many adult patients fall through gaps in care because pediatric cardiologists are trained for children and many general adult cardiologists have limited congenital heart training — which is why specialized adult congenital heart disease (ACHD) programs exist.
Why This Population Needs Specialized Care
Most patients with congenital heart disease need at least one surgery or catheter-based intervention in childhood, and outcomes in adulthood are generally excellent — but lifelong follow-up matters, because repaired defects can develop late complications decades later that a general cardiologist may not know to look for. Adults who had a childhood repair benefit from periodic review at a center experienced in adult congenital heart disease, not just a return to routine primary care once symptoms seem to have resolved.
Common Types Seen in Adults
Atrial septal defect (ASD) — the most common in adults
A hole between the heart’s two upper chambers. Excluding a bicuspid aortic valve and mitral valve prolapse, which are usually not classified as congenital lesions in this context, the ASD is the most prevalent congenital heart defect diagnosed in adults — accounting for roughly 10 to 15% of all congenital heart defects and diagnosed in women about twice as often as men. Small ASDs frequently produce no symptoms in childhood, which is why they are often found for the first time in adulthood, sometimes incidentally. The three main subtypes are ostium secundum (about 65 to 75% of ASDs), ostium primum (15 to 20%), and sinus venosus (5 to 10%).
Ventricular septal defect (VSD)
A hole between the two lower chambers. VSD is the most common congenital heart defect overall and the most common one diagnosed in children, but it is less common in adults specifically — around 10% of adult congenital heart disease cases — because many small VSDs close spontaneously in childhood, and larger ones are typically repaired early. Unlike ASD, an unrepaired VSD volume-loads the left side of the heart and produces a holosystolic murmur along the left sternal border.
Patent ductus arteriosus (PDA)
A blood vessel that normally closes shortly after birth remains open. Like ASD, it is more common in females. A PDA produces a continuous “machinery murmur” and, similarly to VSD, volume-loads the left heart.
Tetralogy of Fallot
A combination of four defects and the most common cyanotic congenital heart condition surviving into adulthood, thanks to surgical repair in infancy or early childhood. Adults with a repaired tetralogy still need lifelong follow-up for issues such as pulmonary valve regurgitation.
Ebstein anomaly
A downward displacement of the tricuspid valve that reduces the effective size of the right ventricle. Some adults present with severe tricuspid regurgitation; others present with cyanosis on exertion caused by a right-to-left shunt at the atrial level.
Cyanotic vs. Acyanotic
Congenital defects are broadly split into cyanotic (allowing deoxygenated blood to reach the body, causing a bluish skin tone) and acyanotic (oxygen-rich blood still reaches the body normally). This describes a mechanism, not a severity ranking — both categories range from mild to serious depending on the specific defect. See our dedicated guides to cyanotic and acyanotic congenital heart disease for more detail.
Congenital Heart Disease Awareness
Congenital Heart Disease Awareness Week is observed February 7 to 14 in the United States. According to the CDC, congenital heart defects affect about 1 in every 100 births each year, making them the most common type of birth defect. An estimated 1.4 million adults and roughly 1 million children in the US were living with congenital heart disease as of the most recent national estimates.
Frequently Asked Questions
The atrial septal defect (ASD), a hole between the heart’s two upper chambers. It accounts for roughly 10 to 15% of all congenital heart defects and is diagnosed in adults more often than other congenital lesions because small ASDs frequently cause no symptoms until later in life. Ventricular septal defect is the most common congenital heart defect overall and in children, but is less common than ASD specifically in adults, since many close on their own or are repaired in childhood.
Small defects, particularly a small atrial septal defect, can cause no symptoms for decades and are sometimes found incidentally on imaging done for another reason. Adults also fall through gaps in care because pediatric cardiologists are trained for children and many general adult cardiologists have limited training in congenital heart conditions, which is why specialized adult congenital heart disease programs exist.
Treatment depends on the specific defect and its severity, and may include watchful monitoring, medication, catheter-based device closure, or surgery. Most patients need at least one intervention over their lifetime, and adults with a repaired defect benefit from regular follow-up with a cardiologist experienced in adult congenital heart disease, since some repairs need monitoring for late complications.
Cyanotic defects allow deoxygenated blood to reach the body, causing a bluish skin tone. Acyanotic defects do not, because oxygen-rich blood still reaches the body normally. This is a mechanism split, not a severity ranking — both categories include defects ranging from mild to serious, depending on the specific lesion.
Sources
- CDC — About Congenital Heart Defects.
- American Heart Association — Congenital Heart Defects.
- Cleveland Clinic — Atrial Septal Defect.
- MedlinePlus — Congenital Heart Defects.
Last updated: August 2026. This article is general information and is not medical advice or a diagnosis. Congenital heart disease varies enormously by defect and individual; decisions about monitoring and treatment belong with a cardiologist experienced in adult congenital heart disease.
