Atrioventricular canal defect

It’s natural for you to be concerned right now about your child’s health—a diagnosis of complete atrioventricular canal defect can be overwhelming. But you can rest assured that at Children’s Hospital Boston, your child is in expert hands.

Consistently ranked among the top pediatric hospitals in the United States, Children’s is home to the world's most extensive pediatric hospital research enterprise; and we partner with elite health care and biotech organizations around the globe. But as specialists in innovative, family-centered care, our physicians never forget that your child is precious, and not just a patient.

What is atrioventricular canal defect?

Atrioventricular canal defect (AV canal or AVC) is a combination of several heart problems that result in a large defect in the center of the heart. The condition is congenital, which means it is present at birth.

The combination of defects includes:

• atrial septal defect (ASD)
  • wall of tissue (atrial septum) that separates the upper heart chambers (atria) has a hole
  • allows oxygen-rich (red) blood to pass from the left atrium through the opening, and then mix with oxygen-poor (blue) blood in the right atrium

• ventricular septal defect (VSD)
  • wall of muscle tissue (ventricular septum) that separates the lower chambers of the heart (ventricles) has a hole
  • allows oxygen-rich (red) blood to pass from the left ventricle through the opening, and then mix with oxygen-poor (blue) blood in the right ventricle

• abnormalities of the atrioventricular (AV) mitral and tricuspid valves
  • These AV valve defects range from a simple gap or “cleft” in one of the mitral leaflets, to a single large “common” AV valve instead of two separate valves.
  • These “common” AV valves can sometimes be leaky (or regurgitant), allowing blood to flow backwards into the atrium when the heart beats instead of being pumped forward out of the heart. This makes the heart less efficient at pumping and can result in more symptoms. (See What are the signs & symptoms of an AV canal defect?)

Why is atrioventricular canal defect a concern? What are its effects?

If it’s not treated, AV canal can cause many problems involving the heart and lungs. When there are holes in the heart, blood flow follows the path of least resistance, which usually means that excess blood flows to the right side of the heart and out the pulmonary artery to the lungs. In those with atrioventricular canal defect, the extra volume of blood handled by the right side of the heart and the lungs can be quite significant, sometimes as much as three times the normal amount.

This extra blood flow through the lung blood vessels often results in higher blood pressure in the lungs and the right side of the heart. Over time, the increased flow of blood and the higher pressure can lead to pathologic changes in the lung blood vessels. Over the long term, these changes in the lung blood vessels can become difficult to treat and irreversible.

As the heart is pumping more blood than normal to the lungs, this adds to the amount of work the right ventricle and the heart as a whole have to do. The heart can become larger or dilated over time, and more muscular than normal. Sometimes as the heart becomes larger, the atrioventricular valve becomes more leaky, which makes the heart less efficient.

Because blood is pumped at high pressure through the septal openings, the lining of the right and left ventricles can become irritated and inflamed. Bacteria in the bloodstream will sometimes infect this injured area, causing a serious illness known as bacterial endocarditis.

What are the signs and symptoms of an AV canal defect?

The size of the septal defects and the functioning of the AV valve(s) (such as the single large common AV valve) will affect the type of symptoms noted, the severity of symptoms, and the age at which they first occur. The larger the septal defects, the greater the amount of blood that passes through from the left side of the heart to the right and overloads the right heart and the lungs.

Signs and symptoms occur in infancy. The following are the most common:

• disinterest in feeding, or tiring while feeding
• poor weight gain
• fatigue
• sweating
• pale skin
• cool skin
• rapid breathing
• heavy breathing
• rapid heart rate
• congested breathing
• blue color
• heart murmur (detected by doctor)

If your baby’s pediatrician notices any of these symptoms, the doctor may refer you to a pediatric cardiologist for testing, diagnosis and a determination of treatment.

Is atrioventricular canal defect genetic?

Genetics may play an important role in the development of atrioventricular canal defect.

• The majority of cases have associated genetic syndromes.
• AV canal affects about 15 to 20 percent of children with Down syndrome.
• The condition affects about 45 percent of children with Down syndrome who have a heart defect.
• About one-third of children born with AV canal also have Down syndrome.
• Fourteen percent of mothers with an AV canal defect give birth to a child with the disease.

What causes atrioventricular canal defect?

It’s important for parents to know that nothing you’ve ingested—and no virus you’ve had—is responsible for your child’s AV canal.

Genetics may play an important role in the development of atrioventricular canal defect. And some studies have investigated a possible link between the use of retinoic acid (for the treatment of acne and facial wrinkles) while pregnant and the development of atrioventricular canal in the fetus.

The structural cause of AV canal is as follows: When the heart is forming during the first eight weeks of fetal development, it begins as a hollow tube. Over time, partitions that form within the tube eventually become the walls dividing the right side of the heart from the left.

Atrial and ventricular septal defects occur when the partitioning process doesn’t occur completely, leaving openings in the atrial and ventricular walls (septa). The valves that separate the upper and lower heart chambers are formed toward the end of this eight-week period, and often they don’t develop properly. Frequently, instead of two separate AV valves (tricuspid and mitral valve), there is a single large common valve that sits between the upper and lower chambers of the heart.

How do you diagnose atrioventricular canal defect?

An atrioventricular canal defectis often first suspected when your doctor hears an abnormal heart sound (heart murmur) when listening to your baby’s heart. Depending on the type of murmur your doctor hears, the doctor may order further testing such as:

• electrocardiogram (EKG)
• chest x-ray
• echocardiogram (cardiac ultrasound)
• cardiac MRI
• cardiac catheterization

For details see Diagnostics for AV canal.

How do you treat atrioventricular canal defect?

Atrioventricular canal defect is treated by surgical repair of the defects within the first several months of a baby’s life. Medications may be necessary until the operation is performed.

For details see Treatment & care for AV canal.

Will my child be OK? Will there be complications?

Open heart surgery at Children’s has among the highest success rates in the United States among large pediatric cardiac centers. In particular, the methods used to repair AV canal have improved greatly in the past two decades, and the operation has a high likelihood of success.

Complications after surgery are not common, but may include the following:

• Residual septal defects can occur, although often these are inconsequential.
• The AV valves, both tricuspid and mitral, can remain leaky, or sometimes the valve openings are narrow (stenotic).
• The exit or outflow from the left ventricle may become narrow.
• Abnormally high pulmonary vascular resistance that was present before surgery may still be elevated, and some may have higher than normal blood pressure in the lungs.
• The heart’s electrical system may have problems.

How common or rare is AV canal?

Atrioventricular canal defect occurs in two out of every 10,000 live births, equally in boys and girls.

What about later in life?

Your cardiologist will help you create a long-term care program as your baby matures into childhood, the teen years and even adulthood. Most people who have had congenital heart disease repair will have an ongoing relationship with their cardiologist. We will treat complications, and will advise on daily-life issues such as exercise and activity levels, nutrition and precautions related to pregnancy.

Surgical techniques for AV canal and its associated defects are continually being refined, and long-term outcomes are continually improving. Nevertheless, patients will need lifelong monitoring and medication, since they’ll always be at some risk for arrhythmias, infections, leaky valves, heart failure or stroke.

A small minority of patients (~10%) will need repeat surgery at some point in later childhood or as an adult, most commonly to address residual mitral valve problems.

Where can my child find care and support when he grows up?

• The Boston Adult Congenital Heart and Pulmonary Hypertension Service (BACH) provides long-term inpatient and outpatient care and advanced therapeutic options for patients with congenital heart disease and pulmonary hypertension as they reach and progress through adulthood.
  
  BACH is an international center for excellence, with physicians and services from Children’s, Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center. The center promotes and supports clinical and scientific research for the advancement of care of these patients, and is a leader in the education of providers caring for this unique population.
   
• The Adult Congenital Heart Association (ACHA) is a national not-for-profit organization dedicated to improving the quality of life—and extending the life—of adults with congenital heart defects. The organization serves and supports many of the adults with congenital heart defects (thought at this time to be as many as one million), their families and the medical community, as well as conducting research and providing advocacy, outreach and education.

FAQ

Q: What is atrioventricular canal defect (AV canal)?

A: Atrioventricular canal defect (AV canal or AVC) is a combination of several heart problems that result in a large defect in the center of the heart. The condition is congenital, which means it is present at birth. The combination of defects includes:

• atrial septal defect (ASD)
• ventricular septal defect (VSD)
• abnormalities of the atrioventricular valves (mitral and tricuspid)

Q: If my child has AV canal, will he be OK?

A: Open heart surgery at Children’s Hospital Boston has among the highest success rates in the United States among large pediatric cardiac centers. With our advanced surgical techniques and timely, family-centered care, the likelihood is very good thatyour child will undergo successful surgery for AV canal.;

Q: How does Children’s treat AV canal?

A: The skilled surgeons at Children’s treat atrioventricular canal defect by surgical repair of the defects within the first several months of a baby’s life. Medications may be necessary until the operation is performed.

For details see Treatment and care for AV canal.

Q: What are the signs and symptoms of AV canal?

A: Signs and symptoms occur in infancy. The following are the most common:

• disinterest in feeding, or tiring while feeding
• poor weight gain
• fatigue
• sweating
• pale skin
• cool skin
• rapid breathing
• heavy breathing
• rapid heart rate
• congested breathing
• blue color
• heart murmur (detected by doctor)

If your child has any of these signs and symptoms, your pediatrician will probably refer you to a pediatric cardiologist for testing, diagnosis and a determination of treatment.

Q: If my child has AV canal, what should I ask my Children’s doctor?

A: After your child is diagnosed with AV canal, you may feel overwhelmed with information. It can be easy to lose track of the questions that occur to you. Lots of parents find it helpful to jot down questions as they arise—that way, when you talk to your child’s doctors, you can be sure that all of your concerns are addressed. 

Some of the questions you may want to ask include:

• What tests will you perform to diagnose my child?
•  What actions might you take after you reach a diagnosis?
• Are there alternative therapies?
• Will my child be OK if he has congenital heart disease?
• Will there be restrictions on my child’s activities?
• Will there be long-term effects?
• What can I do at home before and after surgery to help my child recover faster?

Q: How do you diagnose atrioventricular canal defect?

A: An atrioventricular canal defectis often first suspected when your doctor hears an abnormal heart sound (heart murmur) when listening to your baby’s heart. Depending on the type of murmur your doctor hears, the doctor may order further testing such as:

• electrocardiogram (EKG)
• chest x-ray
• echocardiogram (cardiac ultrasound)
• cardiac MRI
• cardiac catheterization

Q: What should we do at home after surgery for AV canal?

A: Consult your child’s cardiologist for guidance on follow-up care—including:

• wound care while the baby heals
• a nutritional program to encourage weight gain
• an oral hygiene program to prevent infection
• an appropriate exercise regimen to build body mass and achieve fitness

As your baby recovers and grows, be sure to follow a regular program of well-baby/well-child checkups.

Q: What is the long-term outlook for AV canal-affected children?

A: Surgical techniques for AV canal and its associated defects are continually being refined, and long-term outcomes are continually improving. Nevertheless, patients will need lifelong monitoring and medication, since they will always be at some risk for arrhythmias, blood clots, infections, leaky valves, heart failure or stroke. A small minority of patients (~10%) will require repeat surgery at some point in later childhood or as an adult, most commonly to address residual mitral valve problems.

Q: What causes AV canal?

A: It’s important for parents to know that you’ve done nothing to cause your child’s AV canal. Nothing you’ve ingested—and no virus you’ve had—is responsible.

Genetics may play an important role in the development of atrioventricular canal defect. Forty-five percent of children who have Down syndrome with a heart defect have AV canal.

The structural cause of AV canal is as follows: When the heart is forming during the first eight weeks of fetal development, it begins as a hollow tube. Over time, partitions that form within the tube eventually become the walls dividing the right side of the heart from the left.

Atrial and ventricular septal defects occur when the partitioning process doesn’t occur completely, leaving openings in the atrial and ventricular walls (septa). The valves that separate the upper and lower heart chambers are formed toward the end of this eight-week period, and, for some reason, they don’t develop properly, either.

Q: What is Children’s experience treating congenital heart defects?

A: Children’s surgeons treat some of the most complex pediatric heart conditions in the world, with overall success rates approaching 98 percent—among the highest in the nation among large pediatric cardiac centers. In particular, the methods used to repair AV canal have improved greatly in the past two decades, and the operation has a high likelihood of success.

Our experts have pioneered some of medical science’s most advanced heart treatments, now in use around the globe. Children’s is the among the only major pediatric heart centers in the world performing fetal heart interventions for certain congenital defects.

Q: What heart research and innovations are coming from Children’s?

A: A significant amount of the important cardiac research being conducted at Children’s Hospital Boston aims to refine and advance the open heart surgery and catheterization procedures that treat congenital heart defects in newborns and young children—including AV canal.

For details see Research and innovations.

Causes

It’s important for parents to know that nothing you’ve ingested—and no virus you’ve had—is responsible for your child’s AV canal.

Genetics may play an important role in the development of atrioventricular canal defect. And some studies have investigated a possible link between the use of retinoic acid (for the treatment of acne and facial wrinkles) while pregnant and the development of atrioventricular canal in the fetus.

The structural cause of AV canal is as follows: When the heart is forming during the first eight weeks of fetal development, it begins as a hollow tube. Over time, partitions that form within the tube eventually become the walls dividing the right side of the heart from the left.

Atrial and ventricular septal defects occur when the partitioning process doesn’t occur completely, leaving openings in the atrial and ventricular walls (septa). The valves that separate the upper and lower heart chambers are formed toward the end of this eight-week period, and often they don’t develop properly. Frequently, instead of two separate AV valves (tricuspid and mitral valve), there is a single large common valve that sits between the upper and lower chambers of the heart.

Signs and symptoms

• disinterest in feeding, or tiring while feeding
• poor weight gain
• fatigue
• sweating
• pale skin
• cool skin
• rapid breathing
• heavy breathing
• rapid heart rate
• congested breathing
• blue color
• heart murmur (detected by doctor)

If your child has any of these symptoms, your pediatrician will probably refer you to a pediatric cardiologist for testing, diagnosis and a determination of treatment.

When to seek medical advice

Call your health care provider immediately if your baby or child is having difficulty breathing or is breathing rapidly, has a bluish color, tires easily or is uninterested in eating.

Questions to ask your doctor

After your child is diagnosed with AV canal, you may feel overwhelmed with information. It can be easy to lose track of the questions that occur to you. Lots of parents find it helpful to jot down questions as they arise—that way, when you talk to your child’s doctors, you can be sure that all of your concerns are addressed. 

Some of the questions you may want to ask include:

• What tests will you perform to diagnose my child?
• What actions might you take after you reach a diagnosis?
• Are there alternative therapies?
• Will my child be OK if he has congenital heart disease?
• Will there be restrictions on my child’s activities?
• Will there be long-term effects?
• What can I do at home before and after surgery to help my child recover faster?

Who’s at risk

Genetics may play an important role in the development of atrioventricular canal defect.

• The majority of cases have associated genetic syndromes.
• AV canal affects about 15 to 20 percent of children with Down syndrome.
• The condition affects about 45 percent of children with Down syndrome who have a heart defect.
• About one-third of children born with AV canal also have Down syndrome.
• Fourteen percent of mothers with an AV canal defect give birth to a child with the disease.

Some studies have investigated a possible link between the use of retinoic acid (a medication used for the treatment of dermatologic problems such as acne and facial wrinkles) while pregnant and the development of atrioventricular canal in the fetus.

Long-term outlook

Surgical techniques for AV canal and its associated defects are continually being refined, and long-term outcomes are continually improving. Nevertheless, patients will need lifelong monitoring and medication, since they will always be at some risk for arrhythmias, blood clots, infections, leaky valves, heart failure or stroke.

For teens

If you’re a teen who’s had surgical repair of a congenital heart defect, you have a lot to cope with. Besides the typical issues any teenager faces—from social acceptance to body changes and more—you’ll also have to deal with medical appointments and procedures … some delay of your natural wish for independence … feeling different … and assuming a lot of personal responsibility for maintaining your own good health.

If you feel overwhelmed, depressed or anxious through this important time in your transition to adulthood, speak to your doctor or counselor to get help.

For adults

If you were treated for congenital heart disease as a child, you’re probably being followed by your cardiologist, since complications from early heart disease can arise in adulthood.

You may need lifelong monitoring and medication, since you’ll continue to be at some risk for arrhythmias, blood clots, infections, leaky valves, heart failure or stroke. Going forward, your cardiologist will also advise you on activity levels, pregnancy issues and certain lifestyle choices.

Fortunately, Children’s can help adults with congenital heart defects. Many adults who were patients as babies or children continue to be monitored by the clinicians who have followed them since childhood.

In addition, our Boston Adult Congenital Heart and Pulmonary Hypertension Service (BACH) provides long-term inpatient and outpatient care and advanced therapeutic options for patients with congenital heart disease and pulmonary hypertension as they reach and progress through adulthood.

BACH is an international center for excellence, with physicians and services from Children’s, Brigham and Women’s Hospital and Beth Israel Deaconess Medical Center. The center promotes and supports clinical and scientific research for the advancement of care of these patients, and is a leader in the education of providers caring for this unique population.

What you can do at home after your child’s surgery

Your child’s cardiologist will offer recommendations for post-operative follow-up care, including:

• wound care while your baby is healing
• a nutritional program to encourage weight gain
• an oral hygiene program to prevent infection
• an appropriate exercise regimen to build body mass and achieve fitness

As your baby recovers and grows, be sure to follow a regular program of well-baby/well-child checkups.

AV canal glossary

• aorta: one of the heart’s two great arteries. In a normal heart, the aorta arises from the left ventricle and carries oxygen-rich blood out to the body.

• atrial septal defect (ASD): a congenital (present at birth) heart defect that is usually present in children with AV canal, in which there is an opening in the tissue wall (septum) that divides the two upper chambers of the heart (right and left atria)

• (complete) atrioventricular canal defect (AV canal or AVC): a combination of several heart problems that result in a large defect in the center of the heart involving both atrial and ventricular septal defects and affecting the atrioventricular valves. AV canal must be repaired surgically.

• cardiac catheterization: an invasive diagnostic procedure performed under sedation to obtain detailed visual information and measurements about the structures inside the baby’s heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as the pulmonary artery and aorta.

• cardiac/cardio-: pertaining to the heart

• cardiac magnetic resonance imaging (MRI): a non-invasive diagnostic tool using 3-D imaging technology produced by magnets to accurately determine the blood flow and functioning of your child's heart

• cardiac surgery: surgical procedure performed on the heart or one of the blood vessels connected to the heart

• cardiac surgeon: doctor who performs surgery on the heart. A pediatric cardiac surgeon performs surgery on the hearts of infants and children.

• cardiologist: doctor who diagnoses and treats heart problems non-surgically. A pediatric cardiologist treats infants, children and some adults with heart problems.

• chest x-ray: a diagnostic tool chest to evaluate the size and spatial relationships of the heart within the child’s chest, as well as the presence of AV canal and its associated defects

• cyanosis (cyanotic): blue color of skin, lips and nailbeds caused by a reduction in the amount of oxygen-rich (red) blood circulating in baby’s bloodstream

• congenital heart defect: heart defect present at birth. The heart usually starts to form in the first eight weeks of fetal development. It is thought that most congenital heart defects develop during this period.

• diagnosis: medical determination of illness or disease based on history, physical examinations and advanced technology diagnostic testing tools

• Down syndrome (trisomy 21): a congenital chromosomal disorder resulting from an extra 21st chromosome. The Down syndrome child has a short stature, some degree of mental retardation and a distinctive, flattened facial profile. About 15 to 20 percent of Down syndrome children have AV canal.

• echocardiogram (echo, cardiac ultrasound): a diagnostic tool that evaluates the structure and function of the heart using sound waves that produce a moving picture of your child’s heart and heart valves. The ultrasound can be used to understand flow in the different chambers and to estimate pressures.

• electrocardiogram (ECG, EKG): a diagnostic tool that evaluates the electrical activity of your child’s heart. An EKG is usually the initial test for evaluating the causes of symptoms and detecting heart abnormalities, including AV canal.

• mitral valve: valve that normally sends oxygen-rich (blue) blood from the left atrium to the left ventricle. In AV canal, this valve is usually abnormal and in need of surgical repair.

• patch: a piece of synthetic material or native tissue, used in AV canal surgery to repair the holes in the atrial and ventricular walls (septa).

• pulmonary artery: one of the heart’s two great arteries, which normally arises from the right ventricle and carries oxygen-poor blood to the lungs, where it receives oxygen
   
• symptoms: the presenting reasons why a child needs medical attention. A symptom’s characteristics—such as onset, quality, triggers and severity—help diagnosticians to determine a disease, or to decide which testing is needed to determine the disease.
   
• tricuspid valve: valve that normally sends oxygen-poor (blue) blood from the right atrium to the right ventricle. In AV canal, this valve may be abnormal and in need of surgical repair.
   
• ventricular septal defect (VSD): a congenital (present at birth) heart defect associated with AV canal in which there is an opening in the tissue wall (septum) that divides the two lower chambers of the heart (right and left ventricles)

For in-depth visual information on several of the conditions, diagnostic tools and procedures described above, visit our cardiovascular Multimedia library.

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