New Dimensions in Pediatric Heart Surgery
Dr. Steve Muyskens, Medical Director, Cardiac MRI, 3-D aPPROaCH Lab, Cook Children's, takes us into the world of 3D heart printing and how this advancing technology can take the guess work out of pediatric heart surgery, helping children not only survive complex heart defects, but to enable them to thrive into adulthood.
Meet the speaker
Host: Hello and welcome to Cook Children's Doc Talk. Today we welcome Dr. Steve Muyskens, medical director of the Cardiac MRI program here at Cook Children's in Fort Worth, Texas. Dr. Muyskens, is an endowed chair supporting the expansion of our CMRI program and its diagnostic uses. He has since established the three-dimensional lab for the planning and printing of congenital heart disease, which uses advanced technology to support presurgical planning and family education for patients with complex heart conditions. He is our expert on this subject. So thank you for being with us today, Dr. Muyskens.
Dr. Muyskens: Thank you very much for the invitation.
Host So what exactly is a 3D model? And what is the process for creating that model?
Dr. Muyskens: So I think the important part is to kind of start with the patient. There are conditions with varying degrees of complexity that our current diagnostic modalities fall short in some manner. So those patients have long been difficult to manage. We started realizing that we can use technology like 3D printing and virtual 3D animation to help us better understand their condition. So when we identify that patient, whether it be an older patient who has already had some surgeries, or a newborn who has a very complex heart, who we're hoping to do an initial palliation, or surgical repair on, the first thing we decide is, what is the best modality to obtain the information that we would need to then use that technology. The two most commonly used technologies would be MRI, or cardiac CT. You can use rotational angiography in the cath lab, but that's much less commonly used. Once we have that selection made, the data is obtained by us obtaining a typical CT scan or a typical cardiac MRI. But then that data, which is in a raw form called DICOM. DICOM data is then moved to specialized software. And from there, I take that data, and we segment it is the term we use, basically manipulate that data and create a virtual model, essentially, from that information. That model can then be viewed either in the virtual space, so on a typical computer that you would flip around, but then again, you're still only in two dimensions you're looking at in a screen. So then typically, we move on to a 3D printing of that data. So the typical segmentation portion, or manipulation of the data, can vary from anywhere to two to 24 hours of time, depending on the complexity of the model. And then the printing on the actual 3D printer can take anywhere from seven to 15, 16 hours. And then we clean the model and remove kind of some of the support material that's necessary. And we have a replica of the patient's heart.
Host: Wow, remarkable. So can you discuss then with us the different 3D programs you're using right now in the lab?
Dr. Muyskens: Yeah. So our lab is in some ways, like other labs, and in some ways different. When we developed our lab, we started trying to think forward and make sure that, A, where we are five years from now, and then, B, where we are from a understanding of all the different complexities that come along with different forms of heart disease that we were covering all of our bases. So I think in addition to the 3D printing, which is what most people think about, we also have a virtual software program as well. So kind of backing up the 3D printing, which is what most people think of. There's lots of different types of software. And there's lots of different types of printers, we currently use a software program by Materialise, which is that segmentation, that manipulation of the data, or interpretation's probably a better word, of that data, and then creates the virtual model, because it has to be translated to a different language for the printer has to be translated from a two dimensional language into a three dimensional language. And then we currently have a Stratus, this printer that we use that component in different colors in different materials, depending on what we're trying to achieve with our model. And we print on that. The other option is we have something called True 3D by Eco Pixel. True 3D is a software program and virtual viewing station that allows you to manipulate data in virtual 3D. Essentially, like you're in a 3D movie theater, but you're actually in control of the entire environment. The advantages to this are that not everything can be printed. And when you're talking about performing a surgery or doing something invasive, there's also all the other structures become important. Where are the lungs? Where are the airways in relation to the hearts and the vessels. And so 3D printing, you really can't print an entire chest, you can but it's time consuming. And it would be difficult then to visualize some of the structure. So this kind of bridges that gap and allows us to even do some virtual planning on that software. And then the third component that we've been using a little bit is something called 4D Flow, which is a advanced method by MRI to evaluate blood flow in the heart.
Host: So what is the difference then between 3D and 4D?
Dr. Muyskens: 4D is essentially three dimensions. So you have, you know, length, width height, you have your spatial dimensions, and then you're adding a fourth dimension. The fourth dimension is time, we currently use flow in a two dimensional manner in our everyday use for patients that are being evaluated by cardiac MRI. And what this does is it essentially prescribes a coin through a vessel a size of a nickel or a dime, one little slice. And then by using some really fancy computers, we can essentially evaluate what protons are moving through that dimer through that hula hoop is another, I guess, analogy we could use, you can tell how much at which direction how fast. But it's still only one little tiny slice. So what four dimensional flow does is it actually reconstructs the entire heart, chest, vascular space, whatever you want to assess. And then you can not only measure wherever you want, afterwards, but you also visualize all of the blood flow within those vessels. So it actually allows you to track all the protons, all the red blood cells as they move through whether they're swirling and twirling or however direction and gives you a lot of additional information.
Host: It's remarkable. So then it just gives you that much more of a picture of what's happening in the heart, and what's working properly and what's working improperly?
Dr. Muyskens: Exactly. And that's really becoming more and more important, as we've moved from beyond just survival to optimization for our patients andour surgical palliations, right? We're not just trying to get patients to survive, like we were 30, 40 years ago. Now we're trying to have patients that thrive as adults. And so understanding the physiological ramifications of our specific surgical palliations is a kind of a new frontier and 4D Flow allows us to do that.
Host: Technology is exciting in medicine, it is. So what is the benefit then of using these three specialized technologies, the 4D flow, 3D virtual and your 3D printing?
Dr. Muyskens: Yeah, I think all 3D adds information that is unique and not otherwise available with other modalities. So that kind of allows to have a really fully comprehensive 3D lab, the 40 flow, like we talked about allows us to understand the physiology of the anatomy and those vessels and how they're worked and how they look and the valves and what's been leaking. And what's been worked on. The virtual allows us to rapidly assess the anatomy, without having to go through the whole complexity of a segmentation and manipulating the data and interpreting the data, creating a model cleaning the model, and also allows us to look at the relationship of all the structures in the chest to those vessels or to the heart. And then the 3D allows us to really step forward and have this true comprehension of what the heart feels like, looks like to be able to walk through that space.
Host: So in regards to patient surgery, how does this 3D technology help to accomplish that?
Dr. Muyskens: Yeah, I think in a lot of ways, we're still discovering how this technology will be advantageous for patients. I think our feeling and our hopes for the future are that we are creating a better operative plan and operative outcome. So having a really complex congenital heart lesion that we run into that is very atypical from our more conventional forms, can be diagnostically challenging, because looking at our conventional views, things are not where we're used to trying to recreate that heart in your head by using 2D slices by echo or MRI is very difficult. And a surgical kind of template that a surgeon has in their mind where things are, is very different as well. And so being able to take that information, A, identify landmarks for things that they're going to find when they open the chest, you know, next to this airway, or this structure is where I'm going to find these things by using the virtual. And then the 3D really allows that additional information, I think there's two streams of visual processing that we tend to have. And I'm not a neurologist, but the dual stream hypothesis that exists where we have one stream that allows us to do rapid identification, so pattern recognition. You know, when you look at a picture of a path down the woods, you kind of understand that, you know, that's a forest, and there's a path, you've walked down paths in the past, you kind of have an idea as to what that would be like. But then there's a second, which is really the spatial understanding of that space, right? If I had you close your eyes, if you're looking at a picture and put you blindfolded at the beginning of that path, you probably wouldn't feel very comfortable about where you were going to walk. But if I had you walk up and down that path multiple times, and had you close your eyes, you probably have a pretty good idea about walking that path because you rehearsed it, you now have that additional spatial information, having a surgeon being able to look at the heart, hold the heart and understand that and be able to even rehearse that then when they're there. They already have that spatial understanding. So that improves potentially shortening operative times and improving outcomes, less redo surgeries, which are all positive benefits.
Host: Right, because we really don't want to birdbox pediatric surgery, situations. No, exactly, exactly. So are there any specific diagnoses for which these technologies are particularly helpful?
Dr. Muyskens: You know, I think it's a very wide range. And if you look at the institutions that are currently utilizing this technology in some form, the utilization is very expansive from really rather straightforward conditions to conditions that are very complex. At Cooks, and I think probably the majority of institutions that are really invested in the 3D idea, the more complex lesions are, I think, the most useful for exactly what I described before, like, we often times don't have a great understanding because of the limitations of our current 2D technology to understand where things are in these rearranged complex congenital lesions. So different forms of, or more complex forms of, conventional things like tetralogy of fallot, there's many forms where they have VSDs, in different positions, or the great vessels are differently related. And sometimes that repair can then be difficult based on the relationships and it can be somewhat difficult to understand that definitely complex single ventricle things we call upstairs, downstairs, criss cross ventricles, really complex heterotaxy patients who have a multitude of abnormalities and trying to understand whether we can make those patients into a two ventricular repair versus a single ventricle palliation can be difficult, and we don't want to have to make that decision on the fly. And so having that understanding of those relationships, and what the surgeon is going to be able to do by fully understanding their anatomy is probably the most useful use that we have found so far for the technology.
Host: Is there a specific case where this technology was particularly helpful that comes to mind?
Dr. Muyskens: Here, we've had several, I think that one that comes to mind, which is in line with what we talked about a little bit, and the last question is tetralogy of fallot with multiple AP collateral. So tetralogy of fallot is a condition where the division of the great vessels during development is abnormal. And this can result in a large variability of the size and the condition of the blood vessels that feed the lungs. It typically does have a large hole between the bottom two chambers, with that kind of hypertrophied right side, and the larger aorta. Some severe forms, the pulmonary valve, essentially, is atretic. It's not there at all. And then embryologically, what happens to compensate for that in certain patients is multiple blood vessels that are originating off of the aorta, instead of originating off of the heart, feed the different segments of the lung. And so the repairs are very complex and are typically staged, the surgeon has to within the first either weeks to a few months of life has to identify all those individual vessels where they're coming off in the chest, which can be in a large number of places very variable from patient to patient, essentially, then pull those vessels down to reconstruct what would be pulmonary arteries, and then reconnect them to the heart. And so localizing these one to three millimeter vessels in the child's heart, that are tucked behind lungs and airways, and all these other structures is very arduous. So we've had a case here when relatively early on when we started our lab where we obtained a CT scan. And that helped us identify all of those little individual vessels, the relationships to the small, native kind of pulmonary arteries that were still there, but not being fed by any or flow from the heart, the surgeon was able to identify all of those landmarks, we are able to create a map, essentially a virtual map of where all these are in relationships to other vessels. So the surgeon knew where to look and where to dissect and behind what structures that were going to find these small vessels. And then we were also able to then take that data and create a 3D model that the surgeon could actually have in the OR with them, as well, as part of that model, we included the trachea and the main airways so that they could see the relationships and how that was going to be a challenge and a few of the collaterals as far as we call uniform, coalescing, pulling them all together.
Host: So clearly being in the cardiac pediatric field, you guys are highly educated. How has this technology been helpful in taking your education even further?
Dr. Muyskens: Yeah, I think education is a big part about 3D technology that doesn't get talked about a lot. I think, as clinicians obviously, we're very focused on outcomes, improving patient outcomes, but part of that is making sure that the families because they're a big part of that care team and the other providers such as the nurses, other ICU doctors, people that are not involved strictly from a cardiology or cardiothoracic surgical standpoint, have a good understanding of the anatomy as well. And so it's been very exciting to see the response that some of the families have when they actually see their child's heart as cardiologists we may have a great understanding in our head. That doesn't mean we're good artists. And trying to draw a complex three dimensional on a two dimensional piece of paper, let alone be an artist and draw it accurately and well is very difficult. So depending on the cardiologist, it's somewhere between a decent picture and some chicken scratches. And so I think the family's, especially without a basis of medical knowledge and anatomy, oftentimes feel very lost as to what exactly is going on. So to be able to essentially then provide their child's heart to them to look at, and to have a discussion about with the surgeon, or the cardiologist really opens their eyes as to Wow, this is what is normal, I can see that. And this is how my child's heart looks. And here's the problems and this is what's going on. And this is the magnitude of the problem. I think also for recently, we've started including the models at the bedside, at the patient's bedside, both preoperatively and postoperatively. And so that allows the staff and everybody else to understand because children with complex congenital heart disease have very different physiologies. You know, they're what their saturations are supposed to be, what high or low pressures or high or low oxygen administration can do to that patient is very different. So having a full understanding, especially these complex patients that don't fall our typical rules all the time, I think is very helpful. And it's been, again, exciting to even see the staff get excited about the models and understanding what's going on and being able to translate.
Host: What is the direct benefit to the patient in using a center with this type of technology?
Dr. Muyskens: What we talked about a little bit before, I think, you know, we don't know for sure what the ultimate benefit is going to be. But having a better understanding of the patient's anatomy, having better operative plans, being able to rehearse those surgeries, less on the fly decisions, should yield improve outcomes. It also allows us to take on more complex two ventricle repairs and patients that oftentimes other institutions would do a more direct, more straightforward, single ventricle palliation with little bit less risk, but with greater long term risk of complex problems, morbidity, mortality, liver failure, those types of things over the course of their life. I think ultimately, what it really says as a patient or as a parent, is that your institution is really striving to be excellent, you're trying to leave no stone unturned, you're trying to make sure that you have all the information that you're doig the ultimate right surgery, because ultimately, what we do is we want to maximize benefit and minimize risk. And so to do that, for our patients, you have to have everything, you have to have all the information. So having your care at a center that is striving to use this type of new technology or new technologies in general helps you I think feel reassured that that institution's not just trying to do adequate care, but trying to do excellent care.
Host: Absolutely. And you as a parent, I love the thought that what you keep saying is that the problem solving and all of that information is being collected, all the problem solving is being done prior to surgery, as opposed to when my child is on the operating table. So how could the outcomes not come out better? It makes perfect sense. Is it your hope that this just becomes normal protocol?
Dr. Muyskens: Exactly. So the idea is that by having other centers and start to adopt this, because there's a demonstrated benefit, it becomes more of a standard of care instead of the exception.
Host: So what are your future plans with the 3D lab? What exciting stuff is coming up for us?
Dr. Muyskens: As new practitioners of 3D in the last few years, we're really trying to, A, improve on what we're doing. B, expand the availability of the technology to our team. And so one of the first things that we're focusing on is improving the infrastructure by having more places that we can view this 3D technology. Right now, a lot of the virtual 3D especially is very confined to that one monitor ,that one screen. So we're in the process of trying to improve the software and the hardware in our areas where we have conferences in our consult rooms for our patients, and then increasing the number of 3D viewer stations that we have. So that Then, during a regular consultation with a family, we can use all that technology to its fullest versus having to try to move one or two pieces around the hospital continually. And then especially in our joint-cast surgical conferences where we do a lot of our surgical planning discussion, then we'll be able to utilize to the fullest that 3D virtual capability. So actually, everybody in the room can put on a pair of 3D glasses and we can actually have our discussions, break some of our first discussions from top to bottom really in three dimensions versus looking at a bunch of two dimensional slices. Additionally, we have found that just printing a 3D model is not the same as encountering that heart in the chest. And what I mean by that is, when a surgeon goes and#D does an operative repair, they can't pull the heart out and flip it around and open it however they want and then do the repair and then stick it back in. And so having a 3D model that just floating around, provides a lot of information, provides a lot of understanding, but then as far as actually practicing that procedure, it's probably not the best. So we have started working on a supportive template where these models can then be affixed and repositioned so that it is exactly the same position as a surgeon would encounter. So then they can actually look the model, but then they can actually place it like it would be in the chest, when they open the chest. And they can practice and look through, there are very specific views that they'll be able to see because the hearts still tethered, they create a hole, they look through these valves and that view and what access they can get to sew a patch or a baffle or move something, may be very different than they think it's going to be if they just have the model out and floating around. It's really improving the process. and improving the surgical planning for the surgeons and for the families is a big part of that. Additionally, we've started to do more research with 4D Flow, and are working with Siemens on a research project to kind of see how often we can use this, how easy it is to use this new technology. What are all the potential benefits beyond just specific lesions that we already have started to look at? Really again, making it more of a standard of care.
Host: Is that your hope that this technology and benefit to our patient families and our staff go beyond just the cardiac unit? Are we hoping that maybe there are other specialties and patients with other types of diagnoses other than cardiac could benefit from this?
Dr. Muyskens: Definitely. So when I created the 3D Lab, the lab was created for everybody at Cook's to be able to use. Obviously, I'm focused on the cardiac standpoint being a cardiologist, but the utility for other specialties is well established. So orthopedics, neurosurgery, interventional radiology, there are definitely other areas that have a history of benefit. If you look in the medical literature for 3D printing.
Host: Do you predict more programs and or specialties will begin using this technology?
Dr. Muyskens: I do. I think this definitely kind of goes back on some of the things that we talked about. But I think from a specialty standpoint, lots of other specialties could benefit from using this technology for the same patient understanding, caregiver understanding, provider understanding, preoperative planning. And I think we're really just in our infancy right now as far as where this technology is in the medical world as a whole. And I think as we understand it better and hone our craft a little bit, I think you'll continue to see more and more specialties and more and more centers continue to adopt the technology.
Host: So you know, the name of our streaming channel is promise and purpose. How does this technology and how does this work that you do couple, our promise and your purpose in this life? How does it meld your passions together?
Dr. Muyskens: My love is pediatric cardiology. The families, the physiology, the complex anatomy, the fact that every month I see something that I haven't seen before, is exciting and challenging. My interest in noninvasive imaging developed because trying to understand that complex anatomy, trying to help the surgeon understand the anatomy and be able to then execute the best possible surgery for that patient is rewarding. And as a cardiologist, what you you want for your patients, I think the part that drove me to three dimensional imaging was that maybe this goes to the promise that I feel like when you bring your child to me or to any cardiologist, you're promising to do the best you can to take care of that child. That's a big goal and a big aspiration. And too often being the noninvasive cardiologist in the room and providing the information in a conference or to a surgeon in really complex cases and the gap of knowledge between what was reality, what was my understanding, and what was the surgical understanding, left me unsatisfied. I live in a completely virtual world in my head. I'm not a surgeon, I don't hold a child's heart, I look at their heart by imaging. The surgeon, on the other hand, holds their heart and makes the surgical revisions, but they aren't an imager. So their thoughts are tangible. Mine are virtual, essentially in my head. And even just crossing those two bridges on a relatively straightforward imaging can be difficult. But too often I heard, "We'll have to see when I'm in there". Because in really complex heart disease there's no simple plan. There's no ‘everybody does it this way, doesn't work out that way’. And I was very fortunate to work at Cooks, where I have Dr. Tam, who's an amazing surgeon and does amazing things. And so, being able to now use this technology to bridge those gaps and to remove that ambiguity or that lack of complete understanding. I don't want him to ever say I'll have to see when I get in there. And that's kind of what has driven me towards pursuing the 3D Lab.
Host: Well, we're certainly appreciative of all the work and the passion that you bring here, and to our patient families. So thank you, doctor Muyskens.
Dr. Muyskens: Oh, thank you. I'm appreciative of the opportunities that Cook Children's and the Foundation have given me and the support they've given me to pursue my passion.
Host: We're so glad you could join us today. If you'd like to learn more about this program or any program at Cook Children's, please visit us at Cook Children's dot org.