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What is Atrioventricular Canal Defect (AVCD)?

Atrioventricular canal defect (AVCD), also known as atrioventricular septal defect, 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 side valve, becoming one. The blood from both sides of the heart mixes and too much blood circulates through the lungs on its way to the body. Blood also leaks backwards into the atria. All of this of this puts strain on the heart and can cause serious complications if untreated. Partial AVCD involves a hole in the upper chambers of the heart as well as 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 even severe AVCD is promising. AVCD is relatively rare, happening in about 1 out of every 5,000 live births. Babies with Down’s Syndrome have a higher likelihood of AVCD—approximately 45% of children with Down’s Syndrome have some form of congenital heart disease, and about 25% of these have some type of atrioventricular canal defect. In a similar correlation, about 1/3 of children with AVCDs have Down’s syndrome.

How is AVCD diagnosed during pregnancy?

If your doctor suspects AVCD after reviewing your routine ultrasound, he or she may request a fetal echocardiogram, or 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 and decide on the best option for treatment.

How does AVCD affect prenatal management and delivery?

There are no fetal interventions at this time for AVCD. The team at FCI will work with the cardiology team to determine the best timing for delivery, which is usually at term. Most babies with AVCD can be delivered vaginally, 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 immediate access to a team of pediatric cardiologists and neonatologists, along with an established NICU (Neonatal Intensive Care Unit).

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, our surgeons perform surgery to close the large hole by using a patch made either from the heart’s membrane or from synthetic material. The surgeon will then separate the single valve into two, one on each side of the patch, or may need to replace the valve. The surgeaon Over time, the heart’s tissue grows over it. For partial defects, the surgeon often either repairs or replaces the heart’s mitral valve. For complete AVCDs, the surgeon separates the single valve into two, one on each side of the patch, or may need to replace the valve.

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. Your child will need regular follow-up visits with a cardiologist throughout their lives to monitor their progress, but will likely lead relatively normal and healthy lives. Children with AVCD usually need to take antibiotics before minor surgical or dental procedures to protect the heart from bacterial infections. There are possible complications later in life, such as heart valve leaks, that may need additional treatment or even follow-up surgeries.