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Atrioventricular Canal Defect (AVCD) 

What is Atrioventricular Canal Defect (AVCD)?

Atrioventricular canal defect (AVCD), also known as atrioventricular septal defect (AVSD) or AV Canal, is a heart defect in the part of the heart that connects the atria to the ventricles. AVCD varies in severity from complete to partial.

In complete AVCD, there is a hole in the tissue that separates the left and right sides of the heart, and this hole is right in the center of the heart where the atria and ventricles meet. The right-sided valve in the heart fuses with the left-sided valve, becoming one large valve. Complete AVCD allows increased blood flow to the lungs, causing congestive heart failure. Symptoms of congestive heart failure typically develop over the first one to two months of life. These symptoms include trouble feeding, excessive sleepiness, breathing problems, sweating and failure to thrive.

Partial AVCD involves a hole between the two upper chambers of the heart as well as a defect in the mitral valve (the valve between the left atrium and left ventricle). This can be mild enough that some people do not discover this defect until later in life.

If treated early, the prognosis for AVCD is promising. Babies with Down syndrome have a higher likelihood of AVCD; approximately 45 percent of children with Down syndrome have some form of congenital heart disease and about 25 percent of these have some type of atrioventricular canal defect.

How is AVCD diagnosed during pregnancy?

If your doctor suspects a fetal heart anomaly after reviewing your routine ultrasound, he or she may request a fetal echocardiogram (echo), which is an ultrasound of the fetus’s heart. This safe, noninvasive test shows the structure of the heart and how it is functioning, which can help us confirm the diagnosis of AVCD and discuss possible options for treatment after delivery. Our Fetal Heart Team will monitor the baby closely for the remainder of the pregnancy.

How does AVCD affect delivery?

Most babies with AVCD can be delivered vaginally at term, unless there are obstetric indications for another mode of delivery. It is best for these babies to be delivered at a medical center where there is access to a team of pediatric cardiologists and neonatologists, along with an established Neonatal Intensive Care Unit (NICU).

What is the surgery after birth?

Depending of the severity of the AVCD, the treatment can vary. Our pediatric cardiology team will work with you to determine the best timing for surgery.

For complete AVCD, surgery is typically performed in the first four to six months of life. Our surgeons close the holes in the heart using patches. The surgeon will then separate the single valve into two, one on each side of the patches. Sometimes a valve replacement is required if the valves cannot be repaired.

For partial defects, surgery is typically performed around two to four years of age. The surgeon closes the hole between the upper two chambers with a patch and repairs the mitral valve. On rare occasions, the mitral valve may need to be replaced.

What happens after the surgeries, and what is the long-term prognosis?

Overall, if treated early, the long-term prognosis for AVCD is quite good. The child will need regular follow-up visits with a cardiologist throughout their lifespan. Special attention is paid to the repaired heart valves to ensure that they are working correctly.

Additional Resources:

Congenital Heart Disease Resource Page
Provided by the Dorothy and Larry Dallas Heart Center at SSM Health Cardinal Glennon Children's Hospital

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