Congenital Heart Defect: Reparation of Heart Abnormalities in Children
Guest: Dr. Anthony Hlavacek – Pediatric Cardiology
Host: Dr. Linda Austin – Psychiatry
Dr. Linda Austin: I am Dr. Linda Austin. Today I am interviewing Dr. Tony Hlavacek who is a pediatric cardiologist here at MUSC Children’s Hospital.
Dr. Hlavacek, let’s talk about congenital hearts defects in this podcast. In a previous one, we touched on ventricular septal defect, so let’s just kind of review that and then talk about some of the others. Tell us about VSC, ventricular septal defect.
Dr. Anthony Hlavacek: So, your heart has four chambers, two top chambers, called atria, and two bottom chamber, called ventricles, and when you have a hole between the two bottom chambers, that is a ventricular septal defect, or a VSD. What happens with those is blood is allowed to go from the left side of the heart, the side of the heart that already has oxygen, to the right side of the heart, the side of the heart that does not yet have oxygen. This causes a noise, or a murmur, as well as extra blood to go through the lungs, blood that has already gone through the lungs; it causes it to go through twice.
Dr. Linda Austin: So I guess if, by analogy, you had a city where the highway going in, there is a highway going in and one going out, if you had a loop so that instead of going out, it is just circulated back. You have a lot of congestion and that is what happens to those kids.
Dr. Anthony Hlavacek: Exactly.
Dr. Linda Austin: So what is the impact on those children then as they are developing?
Dr. Anthony Hlavacek: Well, often times these ventricular septal defects are small. So if they are small, there really is not much of an impact other than being able to hear it. A little extra blood flow going into the lungs is actually quite well tolerated by most children. But if this hole is large, often times, there will be too much blood flow going to the lungs. We call that pulmonary congestion. As a result, extra fluid goes into the lungs and it causes these children to breathe a little bit fast and have a harder time maintaining their breath. With babies, the main symptom that you will see from this is they will breathe so fast that they just cannot feed very well or their heart is just working so hard that they cannot gain weight, so it is usually fast breathing and poor weight gain.
Dr. Linda Austin: That can be the tip off? Is that right?
Dr. Anthony Hlavacek: Yes.
Dr. Linda Austin: You mentioned in another podcast that often times that can be treated with a diuretic, a fluid pill, to take off the extra fluid.
Dr. Anthony Hlavacek: Yes. If we are able to take off some of this extra fluid, the children can tolerate this heart defect well enough that they can often times grow out of it.
Dr. Linda Austin: Now, another heart defect in children is a so-called atrial septal defect. Tell us about that one.
Dr. Anthony Hlavacek: An atrial septal defect is a hole between the top two chambers of the heart, called the atria. That also allows some extra blood to go from the left side of the heart, the side that already has oxygen, to the right side of the heart. So, again, it creates sort of a short circuit so that extra blood flow goes to the lungs. These are actually better tolerated than the ventricular septal defects, so you can have a fairly sizable atrial septal defect and not have any symptoms.
Now, ventricular septal defects, if we cannot treat those with medicines, we will often times have to do surgery in infancy. But atrial septal defects, we rarely ever have to do anything with those until they get into childhood. They usually do not cause symptoms but we know that over time, this extra blood flow going through the heart will wear the heart out so we will generally repair these between three and five years of age. Some of these defects, if they are well positioned, we can actually repair these in the heart catheterization lab without having to do surgery at all which is a big benefit. That is just an overnight procedure. You come in one day and leave the next. But if the defect is large, often times we will require surgery to fix these defects.
Dr. Linda Austin: So explain the process by which you can repair the defect in the cath lab. What are you actually doing?
Dr. Anthony: What we do is go up through the veins in the leg and into the heart; we can put tubes in the heart. If we put a tube in the heart, we can actually deliver a device. It is a device sort of like a Frisbee, a metallic device, that we can thread up through the veins in the leg and into the heart and release it. It can then clamp down and close the hole inside that top of the atrium.
Dr. Linda Austin: So you insert it in kind of a folded up state, almost like a folded up umbrella, and then deploy it.
Dr. Anthony Hlavacek: Yes. It is compressed in a tube and then we deploy it inside the heart. When we do that, there is a little bit of pain with putting it in and you will have to stay overnight in the hospital, but usually you are able to go home the next day with very little restriction.
Dr. Linda Austin: Let’s talk now about a more complicated congenital abnormality, called Tetralogy of Fallot. Can you explain just what that defect is?
Dr. Anthony Hlavacek: Sure. Tetralogy of Fallot is a little bit complicated. It is the original “Blue baby syndrome.” There have actually been a few movies made about this. What happens is you have a hole between the two bottom chambers, as with ventricular septal defect, but then you also have what we call pulmonary stenosis, that is, some blockage of blood flow towards the lungs. As a result, some blood will come into the heart, go into the right side of the heart, the part of the heart that does not have high oxygen content, and instead of going out into the lungs to pick up oxygen, like blood should, it can skip that and go through the hole in the heart and go right out of the heart, so sometimes these children can have low oxygen levels and that is why they are called blue babies.
Now, most children that have this defect have enough oxygen in their blood to do okay. Their oxygen levels will not be normal but they will be able to tolerate it just fine until we fix the heart defect. But some babies are a little more blue and do not have enough blood going to their lungs so there is not enough oxygen in their blood and we have to fix it earlier. We fix all of these heart defects. This is a heart defect that will not go away; it has to be fixed. We generally try to fix it between three to six months of age, but occasionally children are a little too blue and we have to fix it before they go home from the hospital.
Dr. Linda Austin: So it is like a ventricular septal defect except in the outflow, out of that right ventricle, it is kind of tightened up so that there is high pressure and the blood cannot flow out. So, instead a typical ventricular septal defect where you have the flow of left-to-right and a congested heart, you have the blood re-circulating into Tetralogy. It just bypasses the lungs altogether.
Dr. Anthony Hlavacek. Yes, it just bypasses the lungs. And these children are actually very different than the children with ventricular septal defect because they do not have a lot of pulmonary blood flow. They do not breathe fast. They tend to eat and grow quite well but they have low oxygen levels.
Back 20 or 30 years ago, we used to let these patients grow until they were 2 or 3 years old and they would have blue spells, we would call these Tet spells, but we do not let children get that old anymore. We always repair these when they are still infants.
Dr. Linda Austin: And typically have a good outcome?
Dr. Anthony Hlavacek: Yes, very good outcomes. This is one of the heart defects that we have been fixing for 30 years or so.
Dr. Linda Austin: This, I would assume, cannot be done in the cath lab?
Dr. Anthony Hlavacek: No, this cannot be done in the cath lab. This is also a heart defect that has a very loud heart murmur. If your child had it, your pediatrician would notice it and you would be sent in for evaluation.
Dr. Linda Austin: What causes it? Does it run families?
Dr. Anthony Hlavacek: It can run in families. As with most heart defects, we know that there probably is a genetic component to them. But, this is one that we know is associated with certain disorders, yet some families will have patients with this heart defect. Most of them are what we just call spontaneous, nobody else in the family has this heart defect, and we do not entirely understand why.
Dr. Linda Austin: Just pops up?
Dr. Anthony Hlavacek: Yes, it just pops up.
Dr. Linda Austin: Thank you so much for talking with us today.
Dr. Anthony Hlavacek: No problem.
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