Michael Smith, MD (Host): Welcome to Pediatrics in Practice, a CME podcast. Joining me today is Pezad Doctor, a medical doctor from Children's Mercy. Today, we're diving into an important topic, hypoplastic left heart syndrome, key insights for pediatricians. Thanks for joining me today. I want to dive right into this and ask you what are the key prenatal indicators of hypoplastic left heart syndrome?

Pezad Doctor, MD: Thanks for having me on this podcast. In terms of prenatal diagnosis, as the name suggests, hypoplastic left heart syndrome is usually when the left side of the heart that is mainly the left ventricle, mitral valves, the aorta is small and underdeveloped. And sometimes the spectrum can be that it can be completely absent. It's usually detected prenatally these days when there is a routine antenatal scan done at the OB-GYN's office. And when there's always a suspicion that they cannot see all the four chambers of the heart, that's when moms are referred to cardiology where a fetal cardiologist performs the study and confirms the diagnosis.

Host: So, how can pediatricians support families during this process? This is a hard diagnosis to hear, right? So, any tips, ideas you can give pediatricians for helping their families go through that diagnostic process?

Pezad Doctor, MD: Yes. It's an extremely stressful situation from the time that there may be something wrong with the baby's heart in utero. And by the time they see the fetal cardiologist, it could be sometimes the next day or it could be sometimes weeks. And in the meantime, the parental anxiety can be really striking and nerve-racking.

So, in terms of coordinating care with their primary pediatrician that they know of from their other siblings, or if they have someone in mind who is close to their location to the area, it's definitely helpful for the pediatrician to talk to them about the basic nuances of what this condition means for the child and what are the few palliative surgeries that this child may need eventually in the future. But just to summarize that this is a stressful situation for the parents and having a pediatrician to explain them the nuances of this diagnosis is really important.

Host: What is the prevalence of hypoplastic left heart syndrome?

Pezad Doctor, MD: It is one of the rare congenital heart defects overall. We maybe see like one in every 5,000 live births. In terms of all the congenital heart diseases, it's one in a hundred. So, let's say out of five or 10,000 live births, one may have hypoplastic left heart syndrome.

Host: So, what should pediatricians know about the staged surgical approach to this, and what role do they play in coordinating care between surgeries?

Pezad Doctor, MD: In Children with this condition, there are drastic changes in their hemodynamics throughout their palliative surgeries. They mainly have three surgical palliations, starting from a normal procedure that is soon after the birth in the newborn period. It's to ensure a stable source of systemic and pulmonary blood flow.

 So since the left ventricle is underdeveloped, the right ventricle is fashioned to supply both the circulations. After that procedure, the children at about six months of age undergo the next operation called the Glenn procedure. So in between those first stage and second stage palliatives, that's what's called the interstage period, which is really high-risk mortality in this stage period. So, it's important to maintain good balance between the systemic and pulmonary blood flow. And the best way is by assessing their oxygen saturations. So, we guide pediatricians to make sure they routinely see these children every other week with the cardiologists. That's been the practice during the interstage period to make sure they're gaining weight so that we know that there is good systemic blood flow. They're feeding well, and the oxygen saturations are where we expect them to be between 75-85%.

Host: So gaining weight, watching oxygen saturation, those are the key things during this very important time period.

Pezad Doctor, MD: Exactly. So, we have parents note down how much feeds they have been taking. Sometimes failure to feed or feeding intolerance can also suggest a hemodynamic compromise.

Host: If a child comes out of this like very important phase, does the outcome become better?

Pezad Doctor, MD: Yes, absolutely. Previously, in this interstage, mortality was close to 30%. But due to implementing of home monitoring programs and, you know, with the help of close coordination with the pediatrician and the cardiologist, we have been able to significantly bring down this mortality to close to now 2%. As you said, once they have that second stage where it's a more stable form of pulmonary blood flow, the mortality is much lower.

Host: So, 30% down to 2%. That's significant.

Pezad Doctor, MD: Absolutely. It's all thanks to this close monitoring that we do in these children along with the care of pediatricians.

Host: Yeah. I want to talk about that. So, the main app that's used now is called CHAMP, right? That's a remote monitoring app. How is that? I guess you're saying that's had like some of the biggest impacts and outcomes, huh?

Pezad Doctor, MD: Yes, absolutely. So initially, children, when they would be discharged from the hospital, they would sometimes be not clear understanding of what is normal for these children. You know, these children are, as I said, very high acuity, at least for decompensation.

So with this monitoring, some people call it-- So, Children's Mercy kind of pioneered this CHAMP application where parents are given an iPad, and there is a portal where they have to document the child's weight, the oxygen saturations, the feedings. And we closely monitor with the entire CHAMP team on how they're doing. if there is any concern the parent has about their child at home during this interstage period, they can quickly shoot us a message, and it comes as a page to our on-call cardiologist. We also now have the ability to record videos if they think the child is very blue, the child is grunting, we can remotely access that.

Host: And of course, that helps you. It just speeds up the recognition of an issue that there's something going on. That's fascinating. What are realistic expectations for growth, development, activity levels in children with HLHS? How do pediatricians play a role in facilitating that, counseling families? Can you dive into that a little bit?

Pezad Doctor, MD: Absolutely. Once they have the Fontan operation, that's the third final stage of their palliation. That happens usually at three to four years of age. So, you can imagine that, by the age of four years, they've had multiple heart surgeries, some of which requiring a heart lung machine, long ICU stays, cath procedures. And this is just a routine. There are complications that may even have more cath procedures. So, children's neurodevelopmental, especially in older kids who are studying, we have found learning disabilities, we have found attention deficits and also an increased risk of mental health issues like anxiety, depression in these groups. So, understanding that, evaluating that at the right time is really appropriate so that we can guide them through therapies.

Talking about the physical activity, we know that since these children have one ventricle, which is doing the job of both initially, and then the final palliation is where we want the pulmonary blood flow to go passively to the lungs. So, the children's exercise capacity is reduced, but we encourage pediatricians-- and through our Fontan clinic, we have a multidisciplinary clinic where we closely monitor these children and continue to encourage them to participate in sports.

Host: What about supporting families emotionally not just the patient, but the parents, siblings? How can pediatricians work through that?

Pezad Doctor, MD: It's a very long journey, at the end of the road. And then, despite doing all these palliations, there is a lot of long-term issues these children can encounter. And I think supporting, first understanding what the parents are hoping for their child to finally succeed in. Whether it is final graduation or it's being able to participate in sports or they're having other issues, identifying them early on where they have a close bond with their pediatrician, and noticing that will really help us kind of guide them in the right path. So, I mean, I really appreciate the pediatrician's role in identifying these high stress or behavioral concerns in children and their parents.

Host: You know, when it comes to these rare congenital conditions, one of my favorite questions is talking a little bit about promising innovations. Are there any things that are being studied, clinical trials that are going on that you would like to share with pediatricians that are kind of exciting you?

Pezad Doctor, MD: Yeah. There are a few, actually. The one that is really exciting is the RE-ENERGIZE trial that is going on and it's still actually enrolling participants. So, the idea is that, as I mentioned earlier, these children with Fontan palliation do not have adequate exercise capacity. And when compared to children with a healthy heart, their capacity is about 40% or 50% of that, that we use the oxygen uptake on exercise stress test as a marker of that.

And we have identified that a certain cohort of these children with Fontans have in fact near normal exercise capacity and are able to perform as any other child of that age group. And we found that these children have been enrolled in competitive sports, athletics. They're pursuing postgraduate education. And they have more muscle mass. So, the theory is that since the Fontan palliation is a method of sending passive blood flow to the lungs and augmenting cardiac output, perhaps their activity level, the secondary muscle in their legs is acting as that bump that they're deficient of in their heart. And that is supplying more blood to their lungs, more cardiac output, and they're able to perform very well.

So coming to this clinical trial, they are actually providing an exercise prescription to these children. And every three weeks, they expect them to do certain activities for an hour. And then, they're, again, reassessing their exercise capacity and seeing if that helps improve their exercise capacity as well as reduce any long-term issues with their other organs, like liver failure, lymphatic failure.

Host: That's fascinating to me. That's an amazing, exciting thing that's coming down the line. How do you see this playing out in the future? When does this become something that we'll be able to talk more about with the average patient with hypoplastic left heart syndrome?

Pezad Doctor, MD: This is really a great breakthrough we have through some retrospective studies, identified these findings that, you know, children with more muscle mass activity are overall doing well. And now, we need to implement a more randomized control trial to make sure the cause effect is appropriate.

We had other studies in the past. One of the other clinical trials was fuel study where they gave pulmonary vasodilators and tried to see if there's increased excess capacity in this children with very limited statistical significance. So, I think this approach would be really amazing to see if we are able to improve the quality of life overall. So, more to come on this.

Host: Yeah. Very interesting. I'm sure you'll be watching all of this closely. This was great information. Thank you so much for coming on the show today and sharing your insights.

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