Atrioventricular Canal Defect

An atrioventricular canal defect is a congenital heart defect affecting the center of the heart.

The heart has fourchambers, which are hollow spaces that manage your heartbeat, help pump blood, and make sure there is oxygen in the blood.

The two upper chambers are called atria. The right atrium takes oxygen-depleted blood from the body. The left atrium holds oxygen-rich blood until it is ready to pump through your body.

The two lower chambers are called ventricles. The right ventricle pumps blood out to the lungs to receive oxygen. The left ventricle pumps oxygenated blood through your body.

With atrioventricular canal defect (AVCD), there is a hole in the wall between the heart’s chambers. People with AVCD also have problems with the valves that control blood flow in the heart. Atrioventricular canal defects allow extra blood to flow to the lungs, making the heart work harder than it should.

An atrioventricular canal defect can affect only the atria or all four chambers.

Learn more about AVCD, including its types, causes, symptoms, diagnosis, treatment, and potential risks and complications.

What is an atrioventricular canal defect?

Atrioventricular canal defect is a congenital heart defect characterized by a combination of abnormalities in the heart’s atrial and ventricular septa (the walls between the right and left atria and ventricles) and the atrioventricular (AV) valves.

This defect results in a large hole in the center of the heart where the septa and valves should meet, allowing blood to mix between the heart’s chambers and leading to inefficient circulation.

A congenital heart defect is a heart condition that is present at birth.

An atrioventricular canal defect is sometimes also called an atrioventricular septal defect.

Types of atrioventricular canal defect

Complete AVCD

A complete AVCD involves a large defect in the atrial and ventricular septa and a single common AV valve instead of separate mitral and tricuspid valves. This type is more severe and requires early intervention.

Partial or incomplete AVCD

Partial AVCD involves a defect in the atrial septum and abnormalities in the mitral and tricuspid valves without a significant defect in the ventricular septum. This type may present with less severe symptoms but still requires medical attention.

Causes of atrioventricular canal defect

Atrioventricular canal defects occur before birth, when the heart is developing.

The exact cause of AVCD is not known, though there are factors that may increase the risk of this defect. Risk factors may include:

• Chromosomal abnormalities: AVCD is commonly associated with genetic conditions such as Down syndrome (trisomy 21).
• Family history: A family history of congenital heart defects can increase the risk of AVCD.
• Maternal factors: Exposure to certain environmental factors during pregnancy, such as diabetes, alcohol consumption, rubella, or certain medications, can increase the risk of congenital heart defects.

Symptoms of atrioventricular canal defect

Symptoms depend on the type of atrioventricular canal defect. In both a complete and a partial defect, extra blood flows to the lungs.

Other symptoms may include:

• Cyanosis: Bluish tint to the skin, lips, and nails due to low oxygen levels in the blood.
• Difficulty breathing: Rapid or labored breathing, particularly during feeding or exertion.
• Excessive sweating: Sweating more than needed
• Fatigue: Persistent tiredness and lethargy.
• Poor feeding and growth: Difficulty gaining weight and failure to thrive.
• Frequent respiratory infections: Increased susceptibility to lung infections such as pneumonia.
• Swelling: Swelling in the legs, abdomen, or around the eyes (edema).
• Heart murmur: Abnormal heart sounds heard through a stethoscope, indicating turbulent blood flow through the heart.

Diagnosis of atrioventricular canal defect

Sometimes, an atrioventricular canal defect may be diagnosed before birth during a pregnancy ultrasound or heart imaging.

After birth, an atrioventricular canal defect is usually noticeable within weeks. A health care provider may notice a heart murmur while listening to the baby’s heart.

Diagnostic tests that can help confirm an AVCD include:

• Echocardiogram: The primary diagnostic test for AVCD, using ultrasound waves to create detailed images of the heart’s structure and assess the size and location of the defect and the function of the AV valves.
• Chest X-ray: Visualizes the heart and lungs, showing signs of an enlarged heart and increased blood flow to the lungs.
• Electrocardiogram (ECG): Measures the electrical activity of the heart, identifying abnormal rhythms and signs of heart enlargement.
• Cardiac catheterization: Invasive procedure involving the insertion of a catheter into the heart’s blood vessels to measure pressures, oxygen levels, and obtain detailed images of the heart’s structure.
• Pulse oximetry: Measures the oxygen levels in the blood to assess how well the heart and lungs are functioning.

Treatment of atrioventricular canal defect

One or more surgery is needed to treat an atrioventricular canal defect. During the operation, the surgeon will use a patch to close the holes in the affected areas of the heart. The surgeon will also reconstruct the valves so they can function properly.

A health care provider may also prescribe certain medications before or after surgery to help with symptoms and risks associated with ACVD.

Post-treatment care

• Regular follow-up: Monitoring heart function, growth, and development through regular check-ups with a cardiologist.
• Medication management: Continued use of medications to support heart function and prevent complications.
• Lifelong care: Periodic monitoring and possible additional surgeries or interventions as needed to address long-term complications.

Potential risks and complications

Complications of untreated atrioventricular canal defect

• Heart failure: The heart’s inability to pump blood effectively, leading to fluid buildup and organ dysfunction.
• Pulmonary hypertension: Increased blood pressure in the lungs’ arteries, causing strain on the heart and further reducing oxygenation.
• Arrhythmias: Abnormal heart rhythms, which can affect the heart’s efficiency and increase the risk of stroke or other complications.
• Frequent infections: Increased risk of respiratory infections and complications.

Long-term considerations

• Ongoing monitoring: Regular follow-up with echocardiograms, ECGs, and physical exams to monitor heart function and detect any recurrence or new complications.
• Growth and development: Ensuring normal physical and cognitive development with the support of pediatric specialists.
• Monitoring for recurrence: Continuous surveillance for signs of residual defects, valve regurgitation, or other complications that may require additional treatment.

Impact on quality of life

• Symptom relief: Effective treatment can alleviate symptoms, improve heart function, and significantly enhance overall well-being and quality of life.
• Informed decision-making: Accurate diagnosis aids in making informed decisions about treatment and preventive measures.
• Emotional support: Providing counseling and support to address anxiety, depression, and the psychological impact of living with AVCD or undergoing treatment.

Atrioventricular canal defect (AVCD) is a congenital heart condition that requires early diagnosis and appropriate intervention with surgical treatments and medical management to manage symptoms and prevent complications. Understanding the causes, symptoms, diagnostic methods, and treatment options is essential for effective management. If you or a loved one are experiencing symptoms or have risk factors for AVCD, consulting with a health care provider, pediatric cardiologist, or specialized surgeon will help determine the need for further evaluation and develop a suitable treatment plan tailored to your specific needs and circumstances.