Heart-Explorer Magazine: Dr. Kari, welcome! It’s nice that your surgical schedule allows you to take the time for our interview. Let me briefly introduce you to our readers. You studied medicine in Freiburg from 2003 to 2010, spent a year in New York as a research associate, and after completing your PhD in clinical research, spent a year at Stanford University. Back in Freiburg, you completed your residency in cardiac surgery at the University Hospital in the Department for Cardiac and Vascular Surgery and then went on to specialize in pediatric cardiac surgery as part of a fellowship program at the Children's Heart Center at Columbia University in New York. Since 2019, you have been working as a cardiac surgeon again at the University Heart Center Freiburg. One year ago, you completed your habilitation. Congenital heart defects have played a major role in your career as a cardiac surgeon and in your research interests. Why did this happen? Was there a specific trigger?

Fabian Kari: Not really. But I have always found pediatric cardiac surgery to be one of the most interesting areas of cardiac surgery. A congenital heart defect in a newborn often leads to a completely different circulatory situation and presents us with completely different surgical problems than in an adult with acquired cardiovascular disease. A long life depends on a necessary early correction. And what fascinates me most about surgical therapy is the magnitude of the effect. The improvement after surgery is demonstrated to us directly by the young patients, even in the intensive care unit. Working with the children and their parents is something particularly beautiful.

For pediatric cardiac surgery, you already need a longer training path.

Heart-Explorer Magazine: How many children's hearts do you operate on in Freiburg in a day?

Fabian Kari: We operate on about one child's heart per day. In addition, our colleagues in pediatric cardiology perform several catheter examinations and interventions daily. Our regular service also includes surgery for adults with congenital heart defects, who fortunately grow older and then present with completely different problems.  And when we treat adults on call, we also see the emergencies that can sometimes happen in pediatric cardiac surgery, but this is rather rare.

Heart-Explorer Magazine: In your experience, what is more challenging, an operation on a child's heart or on an adult's heart?

Fabian Kari: Pediatric cardiac surgery is already one of the more challenging areas, but you cannot generalize that it is the most challenging. Many people think of cardiac surgery as a small specialty. In reality, it is very broad. We operate on infants as well as 90-year-olds, and we deal with a wide range of very different conditions, from congenital heart defects to acquired heart disease. However, pediatric cardiac surgery is an area that requires much more intensive training. To be able to operate safely in this area, you need longer training. That requires a lot of special knowledge, some of which can also be used in adult cardiac surgery. In this regard, the fellowship program at Columbia University following my residency was very beneficial to me. In such a large pediatric heart center, you are able to see more rare congenital heart defects in larger numbers and can gain valuable experience. I saw one of the first Rastelli operations on a child with complex TGA at Columbia.

The VSD in itself is not bad for children with TGA.

Heart-Explorer Magazine: A congenital heart defect such as TGA must come as a shock to parents. What do you tell them? How well can this congenital heart defect be treated today? What does it usually mean for life expectancy and quality of life?

Fabian Kari: Maybe I should say that in advance: The first conversations with the parents are held by the colleagues who conduct the prenatal diagnostics. These are specialized gynecologists and pediatric cardiologists. But what I always tell the parents is that if everything goes according to plan during the operation, and in the vast majority of cases it does, the life expectancy and quality of life for their child will be almost normal. Complications are rare, and when they do occur, it is usually at the beginning of the operation or immediately after. But once this is overcome and the children are at home, they usually develop very well and grow up quite normally.

Heart-Explorer Magazine: Is the complex TGA worse than a simple TGA?

Fabian Kari: No, it might sound like that. “Complex” sounds first like “difficult” or “hard to treat medically”. But the term just means that additional cardiac malformations are present. Without any judgment. There is “simple TGA”, which is not necessarily easier. And then there’s “complex TGA”, where, for example, a VSD and a LVOTO (= obstruction of the left ventricular outflow tract) coexist. The VSD in itself is not bad for the children, in fact it can be essential for survival in the beginning. TGA patients with a VSD even have slightly better initial chances as newborns. It’s just that the VSD and the LVOTO then present special technical challenges to the surgeons.

Heart-Explorer Magazine: In what way?

Fabian Kari: The basic problem with transposition of the great arteries is that the pulmonary and systemic circulations run in parallel, not sequential. The two circulations work side by side instead after each other. This is the most inefficient two-circulation system you can imagine. There has to be some mixing of the two circulations or the oxygenated blood will not get where it needs to go to supply the body and its organs with oxygen. Therefore, there have to be places where mixing can occur. And the VSD, while not the best, is at least one place where mixing can take place.

We have checklists and safety nets.

Heart-Explorer Magazine: When is a complex TGA detected? Is it already detected during routine screening during pregnancy? Or does it only become apparent during surgery under certain circumstances?

Fabian Kari: TGA is one of the heart defects that are relatively easy to diagnose during ultrasound examinations in pregnancy. The malposition of the great arteries is usually very easy to recognize. Normally, the great arteries hug each other, they "twist". This is not the case with TGA. And once suspected, the doctor looks very closely for other possible malformations.

Heart-Explorer Magazine: So, there are no surprises?

Fabian Kari: This is extremely rare in the operating room. We don't even start until we have all the detailed information for the surgical plan, for the type of surgery. Nowadays, this is like in the cockpit of a plane. We have checklists and safety nets. Even after the anesthesia begins, we do another ultrasound (transoesophageal) of the heart. And only when everything is confirmed do we start.

The procedure today is far less traumatic to the body than it used to be.

Heart-Explorer Magazine: Since when is TGA operable and what are the different surgical procedures?

Fabian Kari: As early as the 1950s, there was talk of trying to redirect the blood at the atrial level so that the venous blood is directed to the correct arteries via the respective inverted ventricles. Such an atrial reversal operation was first successfully performed by the Swedish heart surgeon Åke Senning in Stockholm in the late 1950s. Hence the name Senning operation.

Heart-Explorer Magazine: However, the Senning operation and the Mustard operation, both of which are based on atrial reversal, are no longer standards today?

Fabian Kari: Exactly. It has been shown that such atrial reversal operations are not without problems. When the right ventricle, which is supposed to maintain the pulmonary circulation, has to maintain the entire systemic circulation, it works well for a while, but at some point, it is overtaxed and then arrhythmias and heart failure occur. In the meantime, arterial switch surgery has become widely accepted. Switching arteries is the obvious thing to do. For a long time, however, this was hampered by the fact that the coronary arteries, which are still very fine and vulnerable in a baby, have to be transferred along with the great arteries.

Heart-Explorer Magazine: For such a delicate procedure, you probably have completely different instruments and materials today than you did back then?

Fabian Kari: That certainly plays a role. I know, not least from the stories of older colleagues with many years of experience, that the instruments, sutures, materials and, of course, the entire surgical technique have evolved considerably. Right down to the heart-lung machine. The whole procedure is certainly less traumatic for the body today than it was a few decades ago.

You need a registry to do this.

Heart-Explorer Magazine: You recently conducted the first long-term study to look at the long-term risks and patient outcomes after different surgical procedures. How did this study come about?

Fabian Kari: The trigger was that there was a lack of clarity about which surgical technique is better when a patient is a candidate for different surgeries. We have already talked about atrial reversal. It's not the standard anymore, so we must exclude it. But the Rastelli operation, the REV procedure, and the Nikaidoh operation are competing. There are different opinions.

Heart-Explorer Magazine: Is that something unusual?

Fabian Kari: There are not so many areas in pediatric cardiac surgery where different therapeutic approaches are used and discussed. There are about 120 standard procedures today, and they are relatively well defined. For most of them, we know how each cardiac malformation should be treated. The demands on quality of therapy is generally very high. But there are still borderline areas, such as the procedure for complex TGA, where there is still disagreement. And with such rare malformation, it is not enough to ask two or three colleagues for their opinion.

Heart-Explorer Magazine: You mean that there are simply not enough cases to make a reliable assessment from your own practice?

Fabian Kari: That's right. And it would also be extremely time-consuming to first collect the data from patients from different clinics. You need a registry like the National Registry, which collects and records data from many patients over a long period of time. That's why we decided to conduct the study in collaboration with the National Registry. To get comparable results, we needed a large enough group of patients that was as homogeneous as possible. Another important advantage of the registry is the continuous medical follow-up data collected over a long period of time. The longer the follow-up and the larger and more homogeneous the cohort, the more reliable the results and the more clarity we gain.

Heart Explorer Magazine: What were your findings? What was the biggest takeaway?

Fabian Kari: If there is one standard that most people can agree on, it is the Rastelli operation. And one of the most interesting things for me was to see that the Rastelli procedure is not only associated with a lot of reoperations in terms of the connection between the right ventricle and the pulmonary artery, which we already knew, but that there are also reoperations that are less specific to the procedure. Patients sometimes had to undergo three or four reoperations. Nevertheless, the mortality is relatively low, even though these procedures are very demanding. Of course, in a registry based on voluntary participation, it must always be assumed that not all patients who die are recorded. The mortality rate could therefore be somewhat higher. Nevertheless, this is a good result.

The body is given more space to heal itself.

Heart-Explorer Magazine: Why are there so many reoperations? Is it related to the animal and artificial materials used and the growth of the body? The animal materials presumably don't last forever, and the plastics used don't grow with the body?

Fabian Kari: Yes, that's part of the answer. In order to close the VSD and at the same time create a kind of bypass where the blood is diverted from the left ventricle to the correct artery like through a tunnel, patches made of plastic are inserted. And these are prone to recurrent narrowing or leakage. It's all rare, but not so rare that you can ignore it. Overall, almost all patients had to be re-operated, and not just because of the material.

And what really impressed me is the safety with which these surgeries are performed. Another interesting finding was that the newer Nikaidoh and REV procedures are both very promising, but the REV procedure resulted in significantly fewer reoperations over time than the Nikaidoh procedures.

Heart Explorer Magazine: What is the advantage of the newer REV procedure?

Fabian Kari: The REV procedure can be done in neonates or in infants. The Rastelli procedure requires the VSD to be a certain size. The older and bigger the child, the better for the surgery. However, surgical experience also shows that anything that can be treated very early - in the neonatal period - often produces good results in terms of structural growth. And with the REV procedure, there are no technical reasons to wait until the child is older or bigger. Another advantage of the REV procedure is the native tissue continuity between the right ventricle and the pulmonary artery. This ensures that there is no need to insert an animal or plastic material in between, but rather a kind of roadway along which the body's own tissue can grow.

Heart Explorer Magazine: Does this mean that the body's own healing powers are more strongly activated?

Fabian Kari: Yes, you could say that. The body is given more space to heal itself. At the end of the day, with all surgical procedures, the healing always has to come from within the body. It doesn't work any other way. We can only "tell" the body that something has to grow in here or something has to get bigger in there, but the body has to do the rest on its own.

You have to be very careful about how you interpret studies like this.

Heart-Explorer Magazine: If your own child is affected and there are different options for surgery: What is the recommendation now based on the study? That is certainly not easy.

Fabian Kari: This is a very important point. You must be very careful with the interpretation of such studies. We have compared procedures that have been used for different lengths of time and are not equally suitable for all patients. The data give us a good indication assuming that REV procedure is very promising in addition to the long-established procedures. However, we cannot yet compare the procedures one-to-one.

Heart-Explorer Magazine: So, it wouldn't be right to conclude that the REV procedure could be the best procedure?

Fabian Kari: No. We have seen that regardless of the procedure and the number of reoperations required, the results are of a high medical standard and the mortality is relatively low. However, we still need to get to the bottom of the promising results with the REV procedure. The decision for surgery really depends on so many factors. It has to be considered on a case-by-case basis.

Heart-Explorer Magazine: This means that the National Registry could also be important for a follow-up study in a few years' time, in which the results of REV procedure can be examined in more detail and in comparison?

Fabian Kari: Absolutely. Without this institution, such studies would not be possible at all, and it is also worthwhile to stay on this topic in the interest of patients and their parents.

Heart-Explorer Magazine: Dr. Kari, thank you very much for this interview.

Heart-Explorer Magazine: If your own child is affected and there are different options for surgery: What is the recommendation now based on the study? That is certainly not easy.

Fabian Kari: This is a very important point. You must be very careful with the interpretation of such studies. We have compared procedures that have been used for different lengths of time and are not equally suitable for all patients. The data give us a good indication assuming that REV procedure is very promising in addition to the long-established procedures. However, we cannot yet compare the procedures one-to-one.

Heart-Explorer Magazine: So, it wouldn't be right to conclude that the REV procedure could be the best procedure?

Fabian Kari: No. We have seen that regardless of the procedure and the number of reoperations required, the results are of a high medical standard and the mortality is relatively low. However, we still need to get to the bottom of the promising results with the REV procedure. The decision for surgery really depends on so many factors. It has to be considered on a case-by-case basis.

Heart-Explorer Magazine: This means that the National Registry could also be important for a follow-up study in a few years' time, in which the results of REV procedure can be examined in more detail and in comparison?

Fabian Kari: Absolutely. Without this institution, such studies would not be possible at all, and it is also worthwhile to stay on this topic in the interest of patients and their parents.

Heart-Explorer Magazine: Dr. Kari, thank you very much for this interview.