Atrial septal defect (ASD)
Wall between the right and left atria
A hole in the wall (septum) between the heart's two upper chambers, the atria. Some small ASDs close on their own during childhood.
Congenital heart conditions
Born with it. Built to play.
Congenital heart conditions are differences in the heart's structure that are present from birth. Many athletes with them stay active — with the right plan from their care team.
The basics
What is a congenital heart condition?
A congenital heart defect is a problem with the heart's structure that is present at birth. It can change how blood flows through the heart and out to the body. Some are found before birth, some at birth, and some not until childhood or even adulthood.
~1%
of U.S. births involve a congenital heart defect — about 40,000 babies each year.
Source: Centers for Disease Control and Prevention — About Congenital Heart Defects (opens in a new tab)#1
Congenital heart defects are the most common type of birth defect.
Source: National Heart, Lung, and Blood Institute (NIH) — Congenital Heart Defects (opens in a new tab)Mild → severe
They range from a small hole in the heart to missing parts of the heart.
Source: Centers for Disease Control and Prevention — About Congenital Heart Defects (opens in a new tab)Any age
Some are found before birth; others aren't detected until childhood or adulthood.
Source: Centers for Disease Control and Prevention — About Congenital Heart Defects (opens in a new tab)
Interactive
Common types, explained
Select a defect to see where it is and what it means.
Simplified schematic, not to scale. The heart's right side is on your left. Cyan rings mark the area involved.
These are a few examples — there are many other types. Only a cardiologist can explain a specific person's heart.
Side by side
Typical heart vs. congenital heart conditions
Pick a condition to compare it with a typical heart: what's different in the structure, in how blood flows, and in how hard the heart works.
What to watch: Watch the red dots with cyan outlines: oxygen-rich blood crosses from the left atrium into the right atrium and goes back to the lungs.
Oxygen-rich blood Oxygen-poor blood Flow caused by the conditionSimplified schematics, not to scale. The heart's right side is on your left.
| Aspect | Typical heart | Atrial septal defect (ASD) |
|---|---|---|
| Structure | A solid wall (septum) separates the right and left atria. | There is a hole in the wall between the atria. |
| Blood flow | Oxygen-poor blood (right side) and oxygen-rich blood (left side) stay separate. | Some oxygen-rich blood leaks from the left atrium into the right atrium and goes back to the lungs. |
| Effect on the heart | Each side pumps only the blood it should. | The right side and the lungs handle extra blood. Some small ASDs close on their own in childhood. |
Structure
- Typical heart
- A solid wall (septum) separates the right and left atria.
- Atrial septal defect (ASD)
- There is a hole in the wall between the atria.
Blood flow
- Typical heart
- Oxygen-poor blood (right side) and oxygen-rich blood (left side) stay separate.
- Atrial septal defect (ASD)
- Some oxygen-rich blood leaks from the left atrium into the right atrium and goes back to the lungs.
Effect on the heart
- Typical heart
- Each side pumps only the blood it should.
- Atrial septal defect (ASD)
- The right side and the lungs handle extra blood. Some small ASDs close on their own in childhood.
The big picture
| Aspect | Typical heart | Congenital heart condition |
|---|---|---|
| What it is | The heart's chambers, valves, and vessels form in the typical way. | A difference in the heart's structure that is present at birth — from mild (a small hole) to severe (missing parts). |
| When it's found | Nothing to find — there is no structural difference. | Before birth, at birth, or sometimes not until childhood or adulthood. |
| Blood flow | Oxygen-poor and oxygen-rich blood follow separate, one-way paths. | Blood flow through the heart or out to the body can be changed. |
| Physical activity | Follow general activity guidelines. | Most people can be physically active. The type and amount are guided by their cardiologist. |
| Follow-up care | Routine check-ups. | Regular cardiology visits, often for life — even after a repair. |
| Warning signs | Stop, tell an adult, and get checked for chest pain, fainting, or a racing heart with dizziness. | The same warning signs apply. Report them right away. |
What it is
- Typical heart
- The heart's chambers, valves, and vessels form in the typical way.
- Congenital heart condition
- A difference in the heart's structure that is present at birth — from mild (a small hole) to severe (missing parts).
When it's found
- Typical heart
- Nothing to find — there is no structural difference.
- Congenital heart condition
- Before birth, at birth, or sometimes not until childhood or adulthood.
Blood flow
- Typical heart
- Oxygen-poor and oxygen-rich blood follow separate, one-way paths.
- Congenital heart condition
- Blood flow through the heart or out to the body can be changed.
Physical activity
- Typical heart
- Follow general activity guidelines.
- Congenital heart condition
- Most people can be physically active. The type and amount are guided by their cardiologist.
Follow-up care
- Typical heart
- Routine check-ups.
- Congenital heart condition
- Regular cardiology visits, often for life — even after a repair.
Warning signs
- Typical heart
- Stop, tell an adult, and get checked for chest pain, fainting, or a racing heart with dizziness.
- Congenital heart condition
- The same warning signs apply. Report them right away.
Sources
- Centers for Disease Control and Prevention: About Congenital Heart Defects(opens in a new tab)
- Centers for Disease Control and Prevention: Living with a Congenital Heart Defect(opens in a new tab)
- National Heart, Lung, and Blood Institute (NIH): Congenital Heart Defects(opens in a new tab)
- National Heart, Lung, and Blood Institute (NIH): Congenital Heart Defects — Types(opens in a new tab)
- National Heart, Lung, and Blood Institute (NIH): Congenital Heart Defects — Living With(opens in a new tab)
How doctors look at the heart
Which test shows what?
Different tests answer different questions. An EKG checks the heart's rhythm; an echocardiogram shows its structure — which is where congenital heart conditions are.
Shows: The heart's rhythm
EKG (ECG)
Sticky sensors record the heart's electrical signals to check the rhythm of the heartbeat. It shows rhythm, not structure, so a normal EKG can't rule out a structural heart defect.
Shows: The heart's structure
Echocardiogram (echo)
A painless test that uses sound waves to create moving pictures of the heart, so doctors can see its chambers, walls, and valves as it beats.
Shows: Oxygen in the blood
Pulse oximetry
A small clip on a finger shines light through the skin to estimate how much oxygen is in the blood.
Doctors decide which tests someone needs. These animations are illustrations, not real test results.
Sports & activity
Staying in the game
There's no single rule for every athlete. Activity plans are personal — and they're made with your cardiologist.
Most people can be active
Most people with congenital heart defects can be physically active, and physical activity can help the heart become strong. The right type and amount depends on the person.
Your cardiologist sets the plan
Ask your cardiologist which activities are safe for you — especially for competitive, contact, or high-impact sports. Decisions are individual and depend on your heart's anatomy, repairs, rhythm, and function.
Competitive sports: evaluate first
For adults with congenital heart disease, the 2025 ACC/AHA guideline says competitive sports participation is reasonable after a comprehensive evaluation by an adult congenital heart disease specialist that weighs each person's risks and benefits.
Repaired doesn't always mean cured
Many people with a heart defect are not cured, even after repair. Regular visits with a cardiologist are important for life — including during the move from pediatric to adult care.
The Heart Lab can't clear anyone to play
Only an athlete's healthcare team can decide which sports are appropriate. Nothing on this page replaces that evaluation.
Every athlete, every time
Know when to stop
Athletes with a congenital heart condition should watch for the same warning signs as everyone else — and should stop, tell an adult, and get checked if they notice any. The American Academy of Pediatrics lists congenital heart defects — including surgically repaired ones — among conditions that can raise the risk of sudden cardiac arrest in young people.
If anyone collapses and isn't breathing normally: call 911, start CPR, and use an AED.
- Chest pain or discomfort during exercise
- Unexplained fainting or near-fainting
- Unusual shortness of breath
- Palpitations with concerning symptoms
- Unexplained exercise intolerance
Make a plan
Checklists for athletes and families
Print or download these and bring them to your next cardiology appointment.
Athlete With a Congenital Heart Condition: Season Checklist
For athletes and families. Review it with your cardiologist before each season.
Checkboxes are for your use on this page only and aren't saved.
Questions to Ask Your Cardiologist About Sports
Bring these to your next appointment. Your cardiologist will tailor the answers to you.
Checkboxes are for your use on this page only and aren't saved.
For coaches & teammates
- Follow the athlete's written activity guidance from their cardiologist — don't set limits or push past them on your own.
- Keep health information private. Share only what's needed with staff who need it, with the family's permission.
- Treat the athlete like any teammate. Most athletes with congenital heart conditions can be active and included.
- Never ask an athlete to play through chest pain, fainting, unusual shortness of breath, or a racing heart with dizziness.
- Make sure the emergency action plan is practiced and the AED is reachable at every practice and game.
Sources
- Centers for Disease Control and Prevention: About Congenital Heart Defects(opens in a new tab)
- Centers for Disease Control and Prevention: Living with a Congenital Heart Defect(opens in a new tab)
- National Heart, Lung, and Blood Institute (NIH): Congenital Heart Defects(opens in a new tab)
- National Heart, Lung, and Blood Institute (NIH): Congenital Heart Defects — Types(opens in a new tab)
- National Heart, Lung, and Blood Institute (NIH): Congenital Heart Defects — Diagnosis(opens in a new tab)
- National Heart, Lung, and Blood Institute (NIH): Congenital Heart Defects — Living With(opens in a new tab)
- American Heart Association: Congenital Heart Disease and Physical Activity(opens in a new tab)
- American College of Cardiology: New ACC/AHA Guideline Addresses Management of Congenital Heart Disease in Adults (2025)(opens in a new tab)
- American Academy of Pediatrics — HealthyChildren.org: Sudden Cardiac Arrest in Young People(opens in a new tab)
Clinical review: pendingUpdated 2026-10-25