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 sided valve, becoming one large valve. Complete AVCD allows increased blood flow to the lungs, causing congestive heart faillure.
Symptoms of congestive heart failure develop over the first one to two months of life. These 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’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 after delivery.
How does AVCD affect delivery?
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 or two patches 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.
For partial defects, the surgeon often closes the hole between the upper two chambers with a patch and repairs the heart’s 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. Your child will need regular follow-up visits with a cardiologist throughout their lifespan.