ELIZABETH STEPHENS: My name is Elizabeth Stephens. I'm a Pediatric and Congenital Cardiac Surgeon at Mayo Clinic. Today, I'll be talking about atrioventricular septal defects, also called canal defects. Today, I'll be showing a repair of complete atrioventricular septal defect.

In this animation, you can see the right atrium, right ventricle, left atrium, and left ventricle. Shown is the large ventricular septal defect and large atrial septal defect. The arrows show the direction of blood flow, from the left side of the heart to the right side. This causes increased volume and work for the right heart. The surgical repair of atrioventricular septal defect involves closing the ventricular septal defect and the atrial septal defect, and then, reconstructing the two valves.

There are two main methods for repairing complete atrioventricular septal defect. One is the double-patch repair. And the second is the modified single patch, which will be shown in the upcoming video. In the modified single patch, there is one patch that closes both the atrial septal defect and the ventricular septal defect. And the edges of the valve are brought down to the top part of the ventricular septum.

This is a four-month-old with Down syndrome and complete atrioventricular septal defect. We are already on the heart-lung machine. And the heart is stopped. We are examining the common valve, first, the inferior part and now, the superior, what's called the bridging leaflet.

Here, we are testing the valve and floating the leaflets. You can appreciate, right now, there is one big valve, instead of separate mitral and tricuspid valves. The first step will be figuring out where the middle will be, where the new septum, that we will create, will go. Now, we are putting in stitches for where the middle will be.

This shows placing each of the stitches, taking vice in the ventricular septum, going through where the midpoint of the common valve is, where it will be partitioned, and then, going through the patch. Again, this partitions the common valve into two valves and, at the same time, will close the ventricular septal defect.

The patch now has been pushed down in place. And we will tie all the sutures. The patch is made of the baby's own pericardium, which is the lining around the heart.

Now, we are examining the mitral valve. And we'll close the gap that you can see near the patch. This is also called the mitral cleft. This gap is closed with fine suture. We are testing the valve again, to make sure that it doesn't leak. And here, you can see the row of sutures closing the cleft.

Now, we are repairing the tricuspid valve in a similar manner. The last step of the operation is to close the atrial septal defect utilizing the same patch. Here, the operation is finished and the heart is beating.