Experts from the Cardiac Center at The Children's Hospital of Philadelphia describe tetralogy of Fallot (TOF), a congenital heart disease characterized by four associated features, one of which is a ventricular septal defect (a hole in the heart). In this video series, you will learn how our experts diagnose TOF before birth, monitor babies during pregnancy, plan for delivery and care after birth, and how they surgically repair tetralogy of Fallot.
How the Normal Heart Works
Kim Persick: I worked at CHOP for 15 years in the echo lab, and we were just fooling around, scanning the baby. And the fetal heart technician, she actually caught this lesion when I was 15 weeks pregnant. And in my family history, there's some heart disease, so they wanted to watch. And about at 20 weeks, they told me they suspected that he was tetralogy. I was okay. Of course, I was concerned and nervous, but I knew where I was and that he would be taken care of.
Thomas L. Spray, MD: All of heart surgery is 50 years old, and we've come from a situation of being able to treat nothing to being able to at least deal with most, if not the vast majority of, congenital heart defects in a way that allows children to grow into adulthood.
Jack Rychik, MD: We live in an era where there are very few things that we really can't take care of.
Thomas L. Spray, MD: Tetralogy of Fallot was one of the first significant congenital heart defects to be addressed surgically.
J. William Gaynor, MD: The first successful operation was done in the mid-1940s at Johns Hopkins.
Thomas L. Spray, MD: So there are many people out there now with tetralogy of Fallot who are in their 30s, 40s, 50s, had children of their own, who are doing fine, who have had repairs of that particular heart defect.
Jack Rychik, MD: Tetralogy of Fallot is a form of congenital heart disease initially described by Etienne Fallot, who was a French pathologist in the mid-1800s. He identified four specific associated features with this particular form of congenital heart disease.
J. William Gaynor, MD: The most important features are that there's a ventricular septal defect, or a hole between the two pumping chambers of the heart, and blockage of blood flow getting out to the lungs. In some children there's almost no blockage and they can actually have too much blood flow to the lungs. In other children the blockage can be so severe that there's not enough blood flow and they're very sick after birth. And sometimes there's a complete blockage, or what's called pulmonary atresia.
Jack Rychik, MD: In order to understand and to comprehend any of the different forms of heart disease that exist, it's very important to make sure we understand what the healthy or the normal heart looks like. The normal heart has two sides, a right side and a left side, and four chambers, the top receiving chambers, or atrium, and the lower chambers, which are thick-walled pumping chambers called ventricles. Red blood cell will come from either the superior vena cava or the inferior vena cava and enter into the right atrium. The blood then flows across the tricuspid valve to the right ventricle. The right ventricle then squeezes and ejects that blood cell into a vessel called the pulmonary artery. The pulmonary artery splits into two vessels, each going to the lungs. As that red blood cell makes its way through the lung, it returns through the pulmonary veins to the left atrium. That blood is now oxygenated. It's picked up oxygen, then goes across the mitral valve into the left ventricle, which does most of the work in terms of delivery of blood flow to the body. That blood cell is now ejected into the aorta to some organ or muscle or skin in the human body. Now, there are some significant differences between the heart in the newborn and the heart in the fetus.
J. William Gaynor, MD: The heart actually is — assumes its almost complete anatomy often before a woman would even know she was pregnant.
Elizabeth Goldmuntz, MD: The heart is actually functioning and pumping blood to the baby throughout most of fetal life.
Jack Rychik, MD: Because the lungs are collapsed in the fetus and it's really the placenta through which much of the oxygenation takes place through the mother, there are various bypass pathways within the fetal heart that direct blood away from the lung. The first is a structure called the foramen ovale. That's communication between the two top chambers of the heart that allows for blood to go from the right atrium to the left atrium. In fact, because there is very little blood that's returning from the lung which would normally go to the left side, the majority of blood that fills the left atrium and left ventricle is coming across the foramen ovale from the right side. Because the lungs are collapsed, there's high pressure, high resistance in the lungs. As blood is ejected out the right ventricle and enters into the main pulmonary artery, very little goes down into the lungs themselves. The majority goes into a structure called the ductus arteriosus, which is the second important communication between the pulmonary artery and the descending aorta. The third structure that's important that connects the umbilical vein to the fetal circulation is a site, a junction, called the ductus venosus. That acts as somewhat of a resister, if you will, in terms of controlling the return of blood from the placenta to the fetal circulation. Birth is a wonderful process and an amazing process, and there's a dramatic change that takes place in what we call the fetal transition, this transition of the circulation from fetal life to neonatal life. As soon as the cord is clamped, the ductus venosus ceases to carry blood to the heart, and it begins to constrict within the first few hours or days of life. The very first thing that happens when a fetus is born is it takes its first breath, the lungs expand, and so the resistance or pressure in the lungs drop, and that promotes blood flow into the lung itself. The ductus arteriosus begins to constrict and is typically fully closed within 24 to 48 hours of life, and blood is now then fully directed into the lung. As the blood returns to the left side of the heart, after traversing the pulmonary circulation and picking up oxygen, the pressure in the left atrium rises just a bit, and the trap door of the foramen ovale, which was open before birth, now begins to close, usually within the first few days of life.
How tetralogy of Fallot Develops
Thomas L. Spray, MD: Tetralogy of Fallot is one of the most common congenital heart defects and probably the first significant congenital heart defect to be addressed surgically.
Peter J. Gruber, MD: The problem with tetralogy of Fallot is that the orientation of the muscle on the inside of the heart is abnormal.
Thomas L. Spray, MD: The septum, the partition between the two ventricles, forms slightly more anterior or frontwards than it should.
Jack Rychik, MD: As that tissue that sits beneath the two great vessels is positioned in front of the pulmonary artery, it results in the four findings of tetralogy. First, there is a ventricular septal defect, or an opening between the two lower pumping chambers. Second, there is a narrowing of the pathway from the right ventricle to the pulmonary artery, or what we call pulmonary stenosis. Third, there is a repositioning of the aorta, which is the vessel that delivers blood to the body, such that it's overriding the two lower pumping chambers. And fourth, there is development of thickening or hypertrophy of the right ventricle as the blood is ejected out through the narrowing of the pulmonary artery.
Peter J. Gruber, MD: So it was described as a tetralogy, or four basic problems. But in general, there's one problem, and that is that the muscle underneath the great vessels, or the aorta and pulmonary arteries, has not formed in the proper location.
Preparing for Baby's Birth
Peggy McCann, RDCS: A lot of times, our families come in, and they're just conscientious of getting the heart adequately diagnosed. And what happens is once they're evaluated by our team, by our group of physicians and the nurse coordinator, they're given a little bit more information. And they're strongly encouraged to have other testing done. And that might be an amniocentesis with a full genetic workup for 22q deletion. They might have a fetal MRI. They might have a more involved fetal ultrasound.
Jack Rychik, MD: Tetralogy of Fallot is a relatively common form of congenital heart disease, and it can be associated with other forms of congenital abnormalities.
Elizabeth Goldmuntz, MD: At this point, specifically what we know about the genetic basis of tetralogy of Fallot is that about 7 percent of those children will have trisomy 21, so they have a complete extra copy of a chromosome 21. We also know that about 15 percent of those children will be missing a piece of chromosome 22, now called the 22q11 deletion syndrome.
Jack Rychik, MD: This abnormality can result in the presence of tetralogy of Fallot, and it can also result in some other types of anomalies including cleft lip or palate, abnormalities of speech or phonation, and in some patients, even development of learning differences or learning difficulties.
Elizabeth Goldmuntz, MD: So you can see that the genetic basis of these disorders can encompass either a complete change in chromosome number, like have a complete extra copy of a chromosome; it can be a missing part or a duplicated part, extra part of a chromosome; or it can be a small change in a specific and single gene.
Peggy McCann, RDCS: It's one thing for us to say we can fix the heart, but it's another thing to say, sure, we fixed the heart, but there's all these other questions that remain to be answered.
Jack Rychik, MD: We treat Tetralogy of Fallot in the same way in these patients that have these various other associated anomalies, but certainly it places things in a little bit of a different context. Some of the patients who have these associated anomalies may require additional care and intervention in the Intensive Care Unit. There might be a need for a bit more attention or perhaps a bit of a longer stay when these children undergo these various surgeries.
Peggy McCann, RDCS: So it's important to know if there's other anomalies because it gives a more comprehensive picture to the parents of what this baby is going to behave like postnatally.
Thomas L. Spray, MD: Babies with Tetralogy of Fallot often do extremely well after birth.
Jack Rychik, MD: Most can safely deliver through a vaginal means. When delivered, however, and when separated from the placenta and no longer receiving oxygenated blood from the mother, we now place the task of oxygenation upon the lungs of the newborn.
J. William Gaynor, MD: If they have enough blood flow at the time of birth so that they don't need an urgent operation, we'll have an elective operation somewhere between two and six months of life.
Thomas L. Spray, MD: And those babies are just like any other baby. The issues really are feeding and growing.
Sarah Tabbutt, MD: Because technically, for the surgeon, they could do it when the baby is first born. It's really no different than doing it when the baby is 3 months of age. It's just, for us taking care of the baby in the ICU, your hospitalization is much shorter if you've already been at home, you've learned how to eat, you've gone through that newborn period. Then if you come back when you're 3 to 4 months of age for surgery, your recovery time in the hospital is very short as compared to if you're a newborn.
Thomas L. Spray, MD: Nowadays, because surgery has developed so much, we can repair this heart defect very routinely somewhere between two and four months of age. So that's when we now electively repair tetralogy of Fallot.
Peggy McCann, RDCS: In patients with a big VSC, with serious overriding of the aorta and seriously stenotic pulmonary valve, we know that, unfortunately, that patient isn't going to have the liberty of waiting for like, say, a repair at 3 to 6 months.
J. William Gaynor, MD: For many children with complex heart disease, there's blockage of the blood either going to the body or to the lungs. And there's a blood vessel called the ductus arteriosus which connects those two arteries. Everybody has one, and it usually closes after birth.
Sarah Tabbutt, MD: You can keep that blood vessel open with a medication called prostaglandins. And so, therefore, by giving a baby prostaglandins, you're actually replicating the same physiology that it had in the uterus, when it was very stable, to when it's outside the uterus.
Jonathan J. Rome, MD: About half of the children who are born with tetralogy of Fallot have a more complicated form of tetralogy where not only is there a hole between the two pumping chambers of the heart, and not only is there a narrowing going out to the lungs, but actually there's no connection at all between the heart and the blood vessels in the lungs. And that's called tetralogy of Fallot with pulmonary atresia.
J. William Gaynor, MD: Obviously, if we know there's a complete blockage, or pulmonary atresia, we know the baby will not have blood flow to the lungs after birth if the ductus closes. So we have to initiate prostaglandin therapy to keep the ductus open.
Jack Rychik, MD: When the ductus arteriosus remains open, that can provide an additional source of blood flow to the lung and, therefore, allow a period of stability and adequate oxygenation until the baby makes its way to surgery.
Sarah Tabbutt, MD: Sometimes they're born with a diagnosis where we're not sure if they're going to need surgery in the newborn period. And so those babies are often started on a prostaglandin medication in the delivery room, which stabilizes the baby so that if there's any problems, they won't occur in the delivery room. And we bring the baby to the ICU, and we stop the prostaglandins, and we let the baby transition to being a baby separate from being in the uterus. And we watch very carefully and see how the child does. And for some of those children, they need the prostaglandins restarted because, in fact, they do need to have their surgery before they go home. And for other children, they're actually okay, and they can go home and come back at a later date.
J. William Gaynor, MD: So not every baby who has a prenatal diagnosis of tetralogy of Fallot will need an immediate urgent operation. If possible, if they have adequate pulmonary blood flow, we will let them — we would like to let them grow for a couple months before they have the surgery. So they would be born. They would come to the Cardiac Intensive Care Unit. They would have an echo to confirm the diagnosis. We would watch them to be sure that they had enough blood flow to the lungs and then let them start to eat and hopefully go home and come back for an elective operation at 2 to 3 months of age.
Surgical Repair for tetralogy of Fallot
J. William Gaynor, MD: When we repair tetralogy of Fallot, there are two major things that we need to do. One is to close the ventricular septal defect so that there's no mixing between the two pumping chambers, and the second is to relieve the blockage to the lungs.
Susan C. Nicolson, MD: It's very, very important that the family feels comfortable with you, as an individual, taking their child from them and that the child recognizes that nothing bad is going to happen to them, that they can do this without being awake for any painful experience.
J. William Gaynor, MD: They'll go to the operating room. The anesthesiologist will put them to sleep. We'll then clean, prepare everything in the chest and abdomen sterilely so that we can do the operation without infection.
Thomas L. Spray, MD: The surgical repair of tetralogy of Fallot involves using the heart and lung machine to support the circulation while the operation is done.
Peter J. Gruber, MD: We're bypassing the heart and the lungs so that the operative field, the area where we're working, is clean, we can see what's going on.
Thomas L. Spray, MD: And then the heart is stopped, and the upper chamber of the heart is opened. And working through the valve that enters the right side of the heart, the hole between the two pumping chambers of the heart is closed with a patch. The patch is made out of a sort of fuzzy Dacron material, so the lining of the heart grows over that and makes it nice and smooth.
J. William Gaynor, MD: There can be blockage below the pulmonary valve, inside the ventricle, from big muscle bundles. The pulmonary valve itself can actually be blocked. The pulmonary valve has three leaflets which open, and if they're fused together, that can cause a blockage because they can't open completely. Sometimes, just by separating the leaflets, you can open the valve. The pulmonary valve is a circle, and the outer layer, that's called the annulus. If that's very small, even if you open up the leaflets, it's like having a small tube. It may be too little. And then you can also have blockage out in the pulmonary arteries themselves. So you can have blockage below the valve, at the valve, and above the valve.
Thomas L. Spray, MD: Sometimes, if the artery to the lungs is quite small, it's enlarged by opening it and putting a small patch over it to make it bigger so blood can easily get to the lungs.
J. William Gaynor, MD: That's called a transannular patch. Some babies will tolerate that very well. Others will need a valve put in at some point in their life. After surgery, we'll make sure that the heart is working okay, that the blood pressure is okay, that there's enough oxygen in the blood, that there's no bleeding. And then usually we leave a couple little tubes inside the heart to let us measure pressures in the heart and give drugs. These come out through the skin. There's also usually two little, blue pacing wires which let us change the heart rhythm. We then leave a drainage tube, and once everything is stable, the baby will come back up to the Intensive Care Unit.
Thomas L. Spray, MD: That operation nowadays takes about three hours to do, from start to finish, and the actual time it takes to do the repair inside the heart is only about 30 minutes. The results with that surgery now are very good. The risk of not surviving that operation, while not zero, is less than 1 percent, so children do extremely well with that particular surgery.
Outcomes for Children With TOF
Kim Persick: Robert comes back once a year for follow-up now. We usually have our annual echocardiograms, and he's on no medication, and he has no restrictions. And he's just an active little boy.
J. William Gaynor, MD: We recently looked at a series of a hundred consecutive children at CHOP, having elective tetralogy repair between — at under 6 months of age, which means they've been out of the hospital and they came back electively for their operation. And every one of those children survived the operation. Now, that doesn't mean the mortality is zero. It means some of those children were very sick. But it does mean that survival for straightforward tetralogy should be excellent. And then the long-term survival also appears to be very, very good.
Thomas L. Spray, MD: The vast majority of children with tetralogy of Fallot will have what is essentially a normal life.
Jack Rychik, MD: By closing the hole and relieving the outflow tract obstruction, one is recreating a situation that's relatively close to the normal heart. However, because of the initial element of narrowing in the right ventricular outflow tract and the need to enlarge the narrowing, there can be leakage of the pulmonary valve.
Thomas L. Spray, MD: And while that is very well tolerated, there are some people, as they get into adulthood, where the amount of that leakage causes the right side of the heart to enlarge and they need to have an artificial valve put in on the right side of the heart. So there is some risk of needing additional surgery after these repairs.
Jack Rychik, MD: There are some patients who continue to have some evidence for residual narrowing even after initial relief of the pulmonary stenosis. In a small percentage of patients, there can be difficulties and problems with narrowing that occurs downstream of the pulmonary artery in the vessels within the lung itself. And those narrowings can oftentimes be treated with catheter-type techniques, or sometimes they may even require placement of a stent through a catheter.
Unknown Speaker: In addition, patients with tetralogy of Fallot repair may have a higher risk for rhythm problems.
Kim Persick: I have a sister that is six years younger than I, and she was born with tetralogy. She was operated on at 15 months, and she — she herself needed a pacemaker.
Unknown Speaker: The use of medication and the requirement for pacemakers has been an issue for older patients after tetralogy of Fallot repair. Our hope is that in the current era of technologic advances that this will be less of an issue for patients as they get older in the future.
Kim Persick: Her heart disease was a little bit more than Robert's. And growing up knowing what a normal life she had, I knew that he would be okay.
Jack Rychik, MD: So repair of tetralogy of Fallot can result in a normal quality of life, and in the vast majority of these patients, there is very little residual problem or issue that they need to deal with. Certainly, these patients need to be followed by a cardiologist, and they need to be seen and evaluated at regular intervals.
Thomas L. Spray, MD: But in terms of the ability to do things and to, you know, have children of your own and grow up and be employed, people with tetralogy of Fallot do extremely well. And there are many adults now with congenital heart disease. In fact, there are more adults now than there are children living with congenital heart disease which, frankly, is a testimony to the fact we've been pretty successful at dealing with these conditions.
Robert E. Shaddy, MD:Our mission ultimately is to help children with heart disease and to help their families get through this difficult problem, to do whatever we can to make their lives better.
Kim Persick: Robert, he's 9 years old now. He is very active. He plays baseball. He plays soccer. He rides his bike. He always wants to be outside. Robert is lovable. He's funny. He's a great kid.
Elizabeth Goldmuntz, MD: What moves me is to work with the families and to work with the children and to give them the best possible care that we can provide. That's first and foremost.
Susan C. Nicolson, MD: And to see them grow and to see them integrated into the family and to see them interface with their parents and their siblings just as you would any other routine and normal child.
Thomas L. Spray, MD: To be able to take the heart of a child and fix it so that the physiology is better and the child has a chance at a long life, that's very gratifying.
J. William Gaynor, MD: There's nothing better than seeing the kids come back when they're 4 or 5 years old.
Susan C. Nicolson, MD: And really see that they're just like any other kid.
Jack Rychik, MD: Through the Fetal Heart Program, we're now able to offer hope and promise for the future for these children to go on to lead happy and healthy lives, and that's what this is all about.
Topics Covered: Tetralogy of Fallot (TOF)