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Single ventricle malformations are a group of congenital heart defects in which one of the heart’s pumping chambers (ventricles) develops improperly and cannot effectively circulate blood. In this video series, you'll learn how experts in the Fetal Heart Program at The Children's Hospital of Philadelphia diagnose and monitor single ventricle malformations before birth, allowing effective treatment to begin right after delivery.
Thomas Spray, MD: The third stage operation is a variant of the Fontan operation.
Peter Gruber, MD: And that generally takes place somewhere after two years, but the child's physiology really tells us the best time to do that.
J. William Gaynor, MD: There are two types of Fontan operations. One is called Lateral Tunnel Fontan in which a baffle is placed inside the heart to redirect the blood flow from the lower part of the body to the lungs. The other is called the Extracardiac Fontan, where we actually use a tube that brings the blood outside the heart up to the pulmonary arteries.
Thomas Spray, MD: But the Fontan operation is based on connecting the veins from the body directly to the arteries to the lungs.
Peter Gruber, MD: Normally, the inferior vena cava, which drains the bottom of the body, attaches to the heart at the inferior, or bottom portion. And what we do is to literally divide this from the heart. We sew up the portion of the heart where the inferior vena cava entered, and then we sew a tube end to end to the remnant of the inferior vena cava. We take this tube and loop it around the side of the heart and sew it into a hole we make into the pulmonary artery. So we essentially bypass the entire heart.
Thomas Spray, MD: It's a more efficient connection because the tube is a very specific size and the blood going through there is not the turbulent. Turbulence loses power. And power loss is a problem if you don't have anything pushing blood through the lungs. It cannot work unless there's low resistance in the lungs. And the key is you have to have a good pumping chamber on the other side which essentially sort of sucks blood through the lungs.
Peter Gruber, MD: Now the one modification is that we put a small hole in the side of the heart and in the side of this graft and sew it together with what's called a fenestration.
Thomas Spray, MD: And the reason we do that is that it's been shown that having that little hole, while it does allow some blue blood to mix with the red blood, it also decreases the risk of developing fluid around the lungs after surgery. Something called a pleural effusion. Effusions used to be the biggest problem after the Fontan operation. Children would have the surgery and do quite well, but they would develop a lot of fluid that collected around the lung, and they'd often have to have a tube in the chest for weeks or even months to drain that fluid. Nowadays, with the use of this fenestration, that is a very uncommon event, whereas it used to be routine.
Contact the Fetal Heart Program for more information