Atrioventricular Canal Defect: Symptoms, Causes, Surgery & Life After — Complete Guide

Medically reviewed by {{Dr. Baraa Alnahhal, MD|https://www.rinnit.com/dr-baraa-alnahhal}} · Last reviewed: October 2026

Quick Answer

Atrioventricular canal defect is a congenital heart defect in which a child is born with a hole in the wall between the heart's chambers plus heart valve problems. Extra blood flows to the lungs, overworking the heart, and untreated it can lead to heart failure. Surgery during the first year of life greatly improves the outlook.

What the research says

• Down syndrome and this defect often go together, but survival in the first year was similar. In a Norwegian registry study of 1,177,926 live births (2000–2019), 1,456 infants had Down syndrome and atrioventricular septal defect was the most common heart defect among them (44.4%); infants with the defect and Down syndrome were more likely to need a cardiac intervention in the first year (adjusted OR 2.52; 95% CI 1.27–4.98) but did not have higher infant mortality than those without Down syndrome (adjusted OR 1.08; 95% CI 0.43–2.70). (Nordklev et al., Acta Obstet Gynecol Scand, 2024) [3]

• Different patch techniques for the complete defect gave similar results. A meta-analysis of 15 studies (2,076 children) comparing modified one-patch with two-patch repair found the one-patch approach shortened bypass and aortic cross-clamp times, with no statistically significant differences in reoperation, mortality or pacemaker implantation; the authors suggested surgery between 3 and 6 months of age. (Wu et al., Pediatr Cardiol, 2020) [4]

At a Glance: Atrioventricular Canal Defect Summary

Topic	Key Facts
What it is	A congenital heart defect: a hole in the wall between the heart's chambers plus faulty valves controlling blood flow
Also called	Atrioventricular septal defect (AVSD), endocardial cushion defect
Who gets it	Babies born with the condition; often associated with Down syndrome and family history of congenital heart disease
Two types	Complete (all four chambers, symptoms in first weeks of life) vs. partial (upper chambers only, symptoms possibly in early adulthood)
Common symptoms (complete)	Blue/gray skin, rapid breathing, excessive sweating, poor weight gain, fatigue, swelling, wheezing
Main complications	Enlarged heart, pulmonary hypertension, repeated lung infections, heart failure
Key diagnosis tools	Before-birth ultrasound, pulse oximetry, ECG/EKG, echocardiogram, chest X-ray, cardiac catheterization; a heart murmur (whooshing sound) is often heard
Treatment	Surgery — usually in the first year of life — with patches to close the hole and valve repair or replacement
Follow-up	Lifelong cardiology checkups; preventive antibiotics before some dental procedures; many lead healthy lives

What Is Atrioventricular Canal Defect?

Atrioventricular canal defect is a mix of problems affecting the center of the heart. The condition is present at birth, which makes it a congenital heart defect. Children born with it have:

• A hole in the wall between the heart's chambers, and

• Problems with the valves that control blood flow in the heart.

The condition is also known as atrioventricular septal defect or endocardial cushion defect.

Here is why that matters: the defect allows extra blood to flow to the lungs. The extra blood forces the heart to work too hard, causing the heart muscle to grow larger. Untreated, the defect can cause heart failure and high blood pressure in the lungs.

Treatment usually involves surgery during the first year of life to close the hole in the heart and repair the valves.

How a Normal Heart Works

To understand congenital heart defects, it helps to know how the heart normally works.

The heart has four chambers. The two upper chambers are the atria; the two lower, more muscular chambers are the ventricles. The right side of the heart moves blood into vessels leading to the lungs, where the blood picks up oxygen. The oxygen-rich blood flows back to the left side of the heart and into the body's main artery — the aorta — which carries it to the rest of the body.

Valves control blood flow into and out of the chambers. They open to let blood in and close to keep blood from flowing backward.

What are the partial and complete types of atrioventricular canal defect?

The defect can involve only the two upper chambers (partial) or all four chambers (complete). In both types, extra blood flows into the lungs. Symptoms depend on which type your child has.

Complete Atrioventricular Canal Defect

In a complete defect, the condition affects all of the heart's chambers:

• There's a large hole in the center of the heart, where the walls between the upper and lower chambers meet.

• Oxygen-rich and oxygen-poor blood mix through the hole.

• Instead of separate valves, there is one large valve between the upper and lower chambers.

• Blood leaks through the large valve into the lower chambers.

• The heart must work harder to pump, and it becomes larger.

Symptoms usually develop in the first weeks of life and generally resemble heart failure. They may include:

• Blue or gray skin color (due to low oxygen levels)

• Difficulty breathing or rapid breathing

• Excessive sweating

• Fatigue

• Irregular or rapid heartbeat

• Lack of appetite

• Poor weight gain

• Swelling in the legs, ankles, and feet

• Wheezing

Partial Atrioventricular Canal Defect

In a partial defect, the condition affects only the two upper chambers:

• There's a hole in the wall between the upper chambers.

• The tricuspid and mitral valves are changed in ways that prevent them from closing all the way.

• Blood can move the wrong way through the irregular valve opening. The mitral valve (between the upper and lower left chambers) is most often affected.

Symptoms may not appear until early adulthood, often driven by complications such as valve problems, high blood pressure in the lungs, or heart failure. They may include:

• Fatigue and weakness

• Nausea and lack of appetite

• Persistent cough or wheezing

• Rapid or irregular heartbeat (also called an arrhythmia)

• Reduced ability to exercise

• Shortness of breath

• Swelling in the legs, ankles, and feet

• Chest pressure or pain

Causes: Why Does This Happen?

Atrioventricular canal defect occurs before birth, while the baby's heart is developing. Experts aren't sure of the cause. However, having Down syndrome might increase the risk.

Risk Factors: Who Is More Likely to Be Affected?

Certain risk factors might make a person more likely to be affected by atrioventricular canal defect.

Risk Factor	Why It Matters
Genetics	Congenital heart disease appears to run in families and is associated with many genetic syndromes; children with Down syndrome often have heart problems present at birth
Rubella (German measles)	Having rubella during pregnancy may affect how the baby's heart develops in the womb
Poorly controlled diabetes	Diabetes that isn't well controlled during pregnancy may affect the baby's heart development — though gestational diabetes generally doesn't increase the risk
Alcohol use	Drinking alcohol while pregnant has been linked to an increased risk of heart defects
Smoking	Smoking during pregnancy increases the risk of congenital heart defects — if you smoke, quit
Some medicines	Taking certain medications during pregnancy may cause heart problems and other birth defects — always tell your healthcare provider about every medication you take

What are the complications of atrioventricular canal defect?

The main complications of atrioventricular canal defect are an enlarged heart, high blood pressure in the lungs, repeated respiratory infections and heart failure.

• Enlargement of the heart — increased blood flow forces the heart to work harder than normal.

• High blood pressure in the lungs — also called pulmonary hypertension. The hole lets oxygen-rich blood mix with oxygen-poor blood, the lungs get too much blood, and pressure builds up.

• Respiratory tract infections — the hole can lead to repeated lung infections.

• Heart failure — if the defect isn't treated, the heart can't pump enough blood to meet the body's needs.

Treatment greatly improves the outlook for children with atrioventricular canal defect — but complications may still occur later in life, including breathing problems from lung damage, irregular heart rhythms, leaky valves (valve regurgitation), and narrowing of the heart valves.

Can atrioventricular canal defect be prevented?

There is no known prevention for atrioventricular canal defect.

Some heart problems are passed down in families — meaning they are inherited. If you have a family or personal history of congenital heart disease, talk with a genetic counselor and a cardiologist before getting pregnant.

How Is Atrioventricular Canal Defect Diagnosed?

The defect may be diagnosed before birth during a pregnancy ultrasound or special heart imaging.

After birth, symptoms of a complete defect are usually noticeable within the first weeks. When listening to a baby's heart, a healthcare provider might hear a whooshing sound — called a heart murmur. Tests used to confirm and assess the defect include:

Test	What It Does
Pulse oximetry	A sensor on the fingertip records blood oxygen; too little oxygen may signal a heart or lung problem
Electrocardiogram (ECG/EKG)	A noninvasive test that records the heart's electrical activity using sticky sensor patches on the chest connected by wires to a computer
Echocardiogram	Sound waves create moving pictures of the heart — it can reveal the hole, valve issues, and how blood flows through the heart
Chest X-ray	Shows the heart and lungs — an enlarged heart or extra blood/fluid in the lungs can be signs of heart failure
Cardiac catheterization	A thin, flexible tube (catheter) travels through a blood vessel in the groin up to the heart; injected dye makes heart structures clearer on X-rays, and pressure can be measured in different parts of the heart

How is atrioventricular canal defect treated by patching the hole and repairing valves?

Surgery is needed to treat a complete or partial atrioventricular canal defect. More than one surgery may be needed. The operation uses one or two patches to close the hole in the heart wall. The patches stay in the heart — they become part of the heart's wall as the heart's lining grows over them.

Beyond closing the hole, other surgery depends on whether the defect is partial or complete:

Defect Type	Valve Surgery
Partial	Repair the mitral valve so it closes tightly; if repair isn't possible, the valve may need to be replaced
Complete	Separate the one large single valve between the upper and lower chambers into two valves; if that isn't possible, the mitral and tricuspid valves may need to be replaced

Many people who have corrective surgery don't need more surgery. However, some complications, such as heart valve leaks, may require treatment later.

Follow-Up Care and Preventive Antibiotics

After congenital heart defect surgery, regular checkups are needed for life with a doctor trained in heart diseases — a cardiologist. Your provider will set how often appointments or imaging tests are needed. Adults treated in childhood may need care from an adult congenital cardiologist, and special attention may be needed around any future surgery — even ones that don't involve the heart.

A congenital heart defect can also increase the risk of infective endocarditis — an infection in the lining of the heart or heart valves. You or your child might need preventive antibiotics before certain dental and other surgical procedures if either of you:

• Has remaining heart problems after surgery,

• Received an artificial heart valve, or

• Received artificial (prosthetic) material during the heart repair.

Ask your healthcare provider whether preventive antibiotics are necessary.

How can people live well after atrioventricular canal defect surgery?

Many children with heart problems present at birth grow up to lead healthy lives. But living with — or caring for a child with — a congenital heart defect can be challenging. Three tips help:

1. Seek support. Talking with others who've been through the same situation brings comfort and encouragement. Ask your provider about support groups in your area.

2. Record the health history. Write down medications, surgeries, other procedures, and their dates — including the surgeon's medical report. This helps providers unfamiliar with your history and eases the transition from pediatric to adult care.

3. Ask about sports and activities. Many people with a successful repair have no activity restrictions, but some need to limit exercise or sports. Your provider can say which activities are safe.

Pregnancy After Repair

Those who had surgery before permanent lung damage occurred are often able to have a successful pregnancy. However, pregnancy is not recommended if serious heart or lung damage existed before surgery. Before becoming pregnant, talk with an adult congenital cardiologist — a heart doctor trained in congenital heart disease — about possible risks and any special care needed during pregnancy.

How should you prepare for an atrioventricular canal defect appointment?

You or your child might be referred to a doctor trained in heart conditions — a cardiologist. Here's how to get ready.

What You Can Do

1. Write down all symptoms, including any that seem unrelated to the reason for the appointment.

2. List all medications, vitamins, and supplements, including doses.

3. Write down important medical information, including other health conditions.

4. Write down questions to ask your healthcare provider.

5. Find out whether your family has a history of heart disease.

What to Expect From Your Doctor

Your provider is likely to ask:

• When did you notice symptoms? Are they continuous or occasional?

• What, if anything, makes the symptoms worse or better?

• Did you have diabetes or a viral infection, such as measles, during pregnancy?

• Did you take medications during pregnancy?

• Did you use tobacco or alcohol during pregnancy?

Questions to Ask Your Doctor

• What's the most likely cause of these symptoms?

• What tests are needed? Is there any special preparation for them?

• What treatment do you recommend?

• How can we manage other health problems together with atrioventricular canal defect?

Don't hesitate to ask any other questions you have.

Frequently Asked Questions About Atrioventricular Canal Defect

What is atrioventricular canal defect?

Atrioventricular canal defect is a congenital heart defect present at birth in which a child has a hole in the wall between the heart's chambers plus problems with the valves that control blood flow. It is also called atrioventricular septal defect or endocardial cushion defect. The defect lets extra blood flow to the lungs, forcing the heart to work harder and grow larger.

What are the symptoms of atrioventricular canal defect?

In a complete defect, symptoms typically appear in the first weeks of life and include blue or gray skin, rapid breathing, excessive sweating, poor weight gain, fatigue, and swelling in the legs. In a partial defect, symptoms may not appear until early adulthood and may include shortness of breath, fatigue, arrhythmia, and reduced ability to exercise.

What causes atrioventricular canal defect?

The defect develops before birth while the baby's heart is forming, and experts aren't sure of the exact cause. Having Down syndrome might increase the risk, and risk factors also include family history of congenital heart disease, rubella, poorly controlled diabetes, alcohol, smoking, and certain medications during pregnancy.

How is atrioventricular canal defect diagnosed?

Atrioventricular canal defect may be detected before birth on a pregnancy ultrasound. After birth, a doctor may hear a whooshing sound called a heart murmur, and tests such as pulse oximetry, an ECG/EKG, an echocardiogram, a chest X-ray, or cardiac catheterization confirm the defect and show how much it affects the heart.

Is surgery always needed for atrioventricular canal defect?

Yes — surgery is needed to treat both complete and partial defects. The operation uses one or two patches to close the hole (which become part of the heart wall), plus repair or replacement of the affected valves. Surgery usually takes place during the first year of life, and more than one surgery may be needed.

Can a child with atrioventricular canal defect lead a normal life?

Many children with this condition grow up to lead healthy lives after corrective surgery. Treatment greatly improves the outlook, though lifelong checkups with a cardiologist are required, and some people may need further treatment for valve leaks or other complications.

Is atrioventricular canal defect preventable?

There is no known prevention, since the exact cause is unknown and some cases are inherited. If there is a family or personal history of congenital heart disease, talking with a genetic counselor and a cardiologist before getting pregnant is recommended.

Conclusion

Atrioventricular canal defect is serious at birth, but it is also highly treatable. This guide leaves you with three lessons:

• The center of the heart is where it starts. A hole between the chambers combined with faulty valves lets extra blood flood the lungs — and an untreated heart pays for it by enlarging and eventually failing.

• Complete and partial are very different journeys. A complete defect announces itself in the first weeks of life; a partial defect can stay quiet until early adulthood — which is why symptoms at any age deserve a proper cardiac evaluation.

• Surgery changes the trajectory. Patching the hole and repairing the valves — usually within the first year — greatly improves the outlook, and many children grow up to lead healthy lives with routine cardiology follow-up.

From the first heart murmur to patch surgery and adulthood after repair, this guide covers the full path of living well with an atrioventricular canal defect. If you're exploring related congenital heart conditions, our atrial septal defect complete guide explains another common "hole in the heart" condition.

Disclaimer: This article is for general informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment.

References

1. Mayo Clinic. Atrioventricular canal defect — Symptoms & causes. Accessed October 12, 2026. https://www.mayoclinic.org/diseases-conditions/atrioventricular-canal-defect/symptoms-causes/syc-20361492

2. Mayo Clinic. Atrioventricular canal defect — Diagnosis & treatment. Accessed October 12, 2026. https://www.mayoclinic.org/diseases-conditions/atrioventricular-canal-defect/diagnosis-treatment/drc-20361528

3. Nordklev CB, Gjesdal O, Gunnes N, et al. Down syndrome and associated atrioventricular septal defects in a nationwide Norwegian cohort: prevalence, time trends, and outcomes. Acta Obstet Gynecol Scand. 2024;103(10):2024-2030. PMID 39104126. https://doi.org/10.1111/aogs.14932

4. Wu Y, Kuang H, Wang G, et al. Surgical management for complete atrioventricular septal defects: a systematic review and meta-analysis. Pediatr Cardiol. 2020;41(7):1445-1457. PMID 32583199. https://doi.org/10.1007/s00246-020-02397-w