A Little Something Extra

Friday, October 23, 2009

Day 23 of 31 for 21 - AV Canal

I know I'm skipping over a few questions and answering this one first. I received an email question about Micah's heart defect so I thought I'd address that one as I'm thinking of it.
Almost 50% of babies with Down syndrome have a heart defect. Almost half of those are an atrioventricular canal defect (AV Canal, or AVSD, atrioventricular septal defect). We thought we were in the clear (as it relates to heart defects) before the ultrasound at 24 weeks. The perinatologist was looking for it and didn't find a problem at 21 weeks. So it was a HUGE surprise to us when I had my ultrasound in Milwaukee during our day-long meet and greet with the staff at Children's who would be caring for Micah after he was born.

In a nutshell, an AV Canal is a combination of multiple heart defects: an ASD (hold between the atria), a VSD (hole between the ventricles), and improperly formed valves. Micah had 2 ASD's, 1 VSD, and his valves were a mess. Here's some information from the Children's Hospital website:

Why is atrioventricular canal a concern?
If not treated, this heart defect can cause lung disease. When blood passes through both the ASD and VSD from the left side of the heart to the right side, then a larger volume of blood than normal must be handled by the right side of the heart. This extra blood then passes through the pulmonary artery into the lungs, causing higher pressure than normal in the blood vessels in the lungs.

The larger the volume of blood that goes to the lungs, the higher the pressure. The lungs are able to cope with this extra pressure for a while, depending on exactly how high the pressure is. After a while, however, the blood vessels in the lungs become damaged by the extra pressure.

As pressure builds up in the lungs, the flow of blood from the left side of the heart to the right side and on to the lungs will diminish. This helps preserve the function of the lungs, but causes yet another problem. Blood flow within the heart goes from areas where the pressure is high to areas where the pressure is low. If the septal defects are not repaired, and lung disease begins to occur, pressure in the right side of the heart will eventually exceed pressure in the left. In this instance, it will be easier for oxygen-poor (blue) blood to flow from the right side of the heart, through the ASD and VSD, into the left ventricle, and on to the body. When this happens, the body does not receive enough oxygen in the bloodstream to meet its needs, and children may become cyanotic, or exhibit a blue coloring in their skin, lips, and nailbeds.

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

For those of you who are visual learners, here are some pictures:
If you're interested in even more information, click here.

Micah's congestive heart failure kicked in around 4-5 weeks (he was still in the NICU). For Micah, that meant he started having difficulty breathing (you could see his chest retract), his breathing rate increased, he was occasionally clammy, and he had more difficulty eating. His lungs were working overtime to handle the oxygen-rich blood that was flowing back to his lungs. He was on a few heart meds (digoxin, captopril, and lasix).

Micah had a rough go with his heart surgery (May 5, 2008, on his 4-month birthday). He ended up going back on bypass twice and left the OR with his chest open (they closed him 3 days later). It was a difficult recovery for our little rock star.

Micah still has moderate regurgitation (leakage) of his mitral valve. This is not unusual, but we do want that regurg to become mild rather than moderate. He'll likely be on a heart medication for the rest of his life. But he's doing great. He's at a slightly higher risk when it comes to respiratory illnesses, though, so we're really praying he doesn't get the flu. So far, so good!


Emily said...

Fabulous information!!

Kim said...

Hi! I've been reading your blog for about a year now. My daughter, Catherine, who is now 18 months old, had her AV Canal repair in December at Johns Hopkins. She is doing great! Such a little miracle, we are very blessed! Your blog has offered great information and provided comfort in knowing that there are others who are experiencing some of the same things that we are experiencing. Thanks!