Embolization in evolution: coils, liquids, and the art of hybrid strategy

Episode Transcript

Recorded live from the Cook booth at SIR and featuring leading experts in the field of interventional radiology discussing a wide range of IR-related topics, this is the Cook@ SIR Podcast Series.

Hi, everyone. Welcome to our podcast live from SIR. I’m joined here today by Dr. Chadalavada and Dr. de Korompay, and today we’re going to talk about one of the most technically nuanced and genuinely evolving corners of interventional radiology, and that is embolization. If you trained a decade ago, like most of us in this room today, the conversations and the toolkits looked very different. We started out with, I’d call it a limited tool set, and now as the years pass, we continue to expand. And that’s exactly what our conversation is going to be about today. So this isn’t a device debate. It’s just three IRs from varying practice areas in different environments, talking honestly about how we work through embolization decisions, where those strategies have left us, and where the future holds. We’ll get into the mental frameworks behind the selection, the cases that’s humbled us all, and what it actually means to know when an angiogram is done. So these are the conversations that happen in the hallway. We are going to try to bring that to you today through this podcast. So let’s get into it. So let’s first introduce our co-host today.

Yeah.

Dr. Chadalavada, go ahead and introduce yourself, tell us about your practice, where you are.

Sure. Well, thank you all for having me, Raja and Nevin, it’s a pleasure, and thank you to the Cook team for hosting us. Ram Chadalavada. I am a professor of surgery and radiology at University of Cincinnati. My clinical practice is at a level one trauma transplant center, like many of us, similar to my fellowship training program. A lot of my practice involves anywhere from day-to-day embolization related to trauma, post-transplant interventions, and particularly–my focus has been always on complex IVC filters, venous reconstruction, and such. Very excited–and shout out to Nevin and our Canadian colleagues for hosting us. We’re excited to be here in Toronto.

Yeah. I’ll jump in. My name’s Nevin de Korompay. I trained in Toronto at the University of Toronto. So hope you guys are enjoying my academic town. I practice in Kelowna General Hospital in British Columbia, Canada. It’s kind of near Vancouver. It’s in a tertiary care, 500-bed center. We do everything but transplant, but we’re sort of the only show in town, so we do everything from IO to neuro to trauma. So if it’s in IR, we do it. So it’s a fun practice to be in and it’s really good exposure to the breadth of IR.

Yeah, that’s great that we get to get a practice perspective, our USA and our Canadian colleagues as well.

Absolutely.

Yeah.

And my name is Raja Ramaswamy. I am an interventional radiologist based out of Indiana. And I’m in the United States private practice realm, so much different than Ram, where you practice, and Nevin, where you practice as well. And hopefully we can get some differing perspectives on what each of us faces as far as challenges go.

Embolization is one of those disciplines where the gap between how you were trained and how you actually practice can be pretty wide. So let’s start there. When you look back at your training versus your practice today, what’s the single biggest shift in how you approach embolization? Ram, we’ll start with you.

Yeah, absolutely. I think embolization fundamentally is the same core concept, right? We want to stop the bleeding if it’s a bleeding type of case or hemorrhaging case. We want to decrease our vascular flow. I think fundamentally, to me, what’s changed in the so-called march of science and the march of tools and resources we’ve had is, I think about embolization not as essentially a singular tool that I have in achieving a goal, it tends to be more multi-utilitarian in the sense that I may mix and match a combination of resources, more so than I think I did perhaps when I was in training. I was very much in a heavy pushable coils type of training program, and that’s still amazing technique and technical features, but I would say I take a more of a multi-modality approach or thought process today.

Yeah, I would echo that, I think. When I was a trainee, I think I’d only ever seen a pushable coil. I didn’t even know the other ones existed, and our toolkit has developed incredibly since then. And so I think I had one, or two, or three options for any case, and now I have a multitude of options. And even within those little subsections, there’s all these little fine details between the equipment available to you, so you can tailor that case to kind of hit the impact you want, or if there’s a safety thing you’re worried about, there’s a lot more modification. Sort of an infinite increase in the complexity and the subtleties of the different devices or agents we use.

I think one of the things that our United States-based audience wants to hear about–specifically with your practice, Nevin–we always hear about value-based care and a limitation of the number of tools or embolization products that you may or may not have. Can you comment on that? Do you feel like you have the same array of tools that your United States counterparts do? Do you feel like there’s more attention on your practice of trying to contract cost? How does that work in your market?

Yes. Certainly coming from the People’s Republic of Canada, it’s a little bit of a different approach with socialized medicine. I think the biggest issue I’ve encountered in my career so far has been scaling it. So when our budgets–the way our things are set up, like a practice, we have a hospital budget, so once you have that budget, you can spend that money how you want. Your cases and your caseloads, the agents you choose, they’re not tied to a particular procedure or case. So for instance, if I wanted to do PAE or women’s health, like a pelvic congestion syndrome case, I didn’t need to get an insurance company to sign off on that, for instance. There’s a lot of autonomy in the physicians and how you choose your cases, and you can choose whatever agents you want. The issue is getting those agents.

So for me, when I was scaling it–it’s a radiology department budget, and we were a smaller hospital, and our budget items were things like vials of contrast and drainage catheters, so when you start throwing thousands of dollars around for coils, a bunch of administrators’ heads popped out of their eyes and said, “Whoa, this is difficult to manage,” and they wanted to contain costs. That being said, now I work at a stroke center, we do stroke, coils and things are kind of a rounding item on our budget list now because of the relative costs. So I have access to anything that’s improved, as long as it’s improved approved by our government. So there’s a few items we don’t have access to, some of the newer liquid embolics, but everything else is on the table and I have access to the full gamut of neuro coils. I think some of the liquid embolics are a little bit different, so ones we have access to that you guys don’t have access based on IFUs and things like that, like some of the glue selections, I think we have a bit more options here.

But yeah, basically it’s up to me to decide what case I’m going to do and whether I want to spend more money or less money. I think at the end of the day, we all want to just get the case done however we can do it safely. But once you’re moving past that and getting a little finesse-y, I think then, certainly, cost control becomes more of a consideration for us.

Yeah. That’s really interesting. I can tell you, the first half of my practice was in academics and the second half has been in the private world. And I will say when I was in the academic realm, we had access to everything, carte blanche. There was no cost containment whatsoever, so we got every new tool variation to use in our practice, which was fantastic, especially if you’re, you know, beginning your career out that way.

Yeah.

And then when I moved over to private, after COVID we went through this restructuring–you know, value analysis committees started to form, be a little more stringent.

Yeah.

So now we look at cost on everything, so we cannot get everything that we want in anymore. In fact, we are encouraged to use more pushable coils over everything else because it is more cost-efficient. So Ram, what do you think about that?

I was going to ask you, have you checked back with your academic program? I’m curious if that change has also happened there, because I would say the landscape was very similar to what you were saying, and it’s actually a reflection of time. I feel like COVID and that 2021 transition also led to, at academic practice, a significant emphasis on value analysis of that committee, each person pitching and creating a economic basis for why, what is the yield technically? What’s the effect on economics of the decision? What’s our expected volume utilization? Can we look at pricing discounts? I feel like there’s been a change in the academic world as well similarly, Raja. I’d be probably surprised to hear if any of the academics literally have that wide-open horizon still.

Yeah, you know, that’s why we’re here today to talk about these things. So it sounds like in your institution, you guys have contracted down. It’s not like the old days, we’ll put it.

Yeah, absolutely. I think we’re being held responsible for any and every SKU item, like any other major corporation or company that is putting an item up on the shelf, there’s a decision and discussion, “Should it be there and what shelf? Should it be on the high or low shelf line?”

Okay. Well, that’s a great perspective. So let’s dive a little more into some technical thinking. Before we talk about things like combining agents, let’s talk about where you start. So let’s be more direct. When you have a case, a standard, let’s just say a GI bleed, what are you reaching for first? Are you going to coils? Are you going to liquids? Walk me through your process for choosing an embolic agent.

I can shed some light on this, Raja. So for me, when I look at a GI bleed, first I want to know where is it? Is it an upper GI bleed? Is it the typical GDA or some duodenal distribution versus some lower GI bleed? Is it somewhere in the vasa recta, in the right lower quadrant or left lower quadrant that’s causing it? So I think initial delineation of upper and lower, and what kind of branching that I’m dealing with, plays a significant role.

Typically, for me in the GDA distribution, if there is some post-surgical anatomy or such, I’m thinking about how to get micro level of embolization. I may think about glues, but I would say typically I’m in the coil sector. You think about the first coil and the last coil, and I may pack it with something else, but typically coils in the upper. Whereas in the lower GI bleed, depending on how downstream and where I am trying to set something down, I may be thinking about a liquid embolic and non-adhesive rather than–or adhesive–embolic. Or sometimes you may want to just get into a distribution tree, a single coil in that distribution takes down the pressure head, and so–I think about it a little bit more comprehensively in that sense, but that’s my default.

Okay. And Nevin, how about you?

Yeah, I think I’d echo that. I think it all comes down to the vascular bed you’re dealing with. And I think the point that’s been made there is that you want to see where you go in, is there surgical anatomy? Is it end organ? Is it really distal? I think generally because I’m pretty comfortable with coils in the GI system, you know, there’s usually pretty good collaterals, especially in the upper, I’m usually reaching for coils. Very rarely in the GIMI, because I think with the sort of current generation of really good microcatheters, support catheters, things like radial access, I can get really far out into the arcades. So it’s almost like you feel good about yourself if you can get that really cute distal coil or almost half in, half out at the lumen. So generally with–yeah, location, location, location. GI, vascular bed, I’m going to reach for coils first. And usually my glue or liquid embolic is more of a troubleshooting situation when things aren’t going how I want them to go.

Yeah. That’s really interesting. There are newer liquid embolics out, and I find that–I’d say 80 to 90% of the time I am reaching for a coil first, but that other 10% time now, I am reaching for the liquid embolics because I find that we’ve all used NBCA glue. It’s somewhat of a circus to get that going. Another table, everyone gets super excited. I even spray some of the D5 on everyone’s gloves so we don’t polymerize on the table. There’s a whole song and dance that goes along with it.

You got to get your ratios right, yeah.

Getting the ratios right–

Your cocktail.

–cocktails, right. But I’ll say that with these newer liquid embolics, it has cut that uncertainty out. It’s cut a lot of that rigamarole that goes into preparation out. So I find that I’m using glue quite a bit more than I would’ve expected, especially 10 years ago. But I would say the workhorse is the coil and then secondary is the glue.

How was that process, for you to introduce these new glue–like, you said in private practice it was a little–? Did they come to you and say, “Hey, we got approached by our business partners about this opportunity,” or did you bring it up? How did that work?

Yeah, it’s a little more nuanced, I would say. So in our practice–and I have to delicately tread amongst some of these words–but with our generation, when we were learning, it was, “Use your pushable coils first. Use the most cost-efficient stuff first.” I will tell you, all the new hires that we have, they are trained mostly on detachable coils. And so in our IR practice–we have 17 IRs–I’d say nine of them are five years and under of attending experience. Those nine to 10 IRs are mostly using detachable coils.

So what does this do? This tells us there is room to bring in another product because you’re going to ultimately decrease the cost of using these detachable coils. So in a roundabout way, that’s how we got these liquid embolics in, because of our use of detachable coils has skyrocketed. So it’s looked at as a cost savings.

Wow, interesting.

Right.

Yeah.

That’s the interesting part of our healthcare system. So you could tell all the younger, newer trained folks, “Hey, you guys need to use these pushable coils more.” But ultimately the bottom line and what people say is that they don’t feel comfortable just using pushable coils. They want to use the detachable coils for the safety, under the safety guise. So that’s how we were able to get those liquid embolics in.

Yeah. Got it. Interesting. You know, one unique perspective: When I joined University of Cincinnati practice, there was already a higher utilization of detachable coils than pushable, compared to my training program. So in some ways, I was a little surprised, but I think we had the similar outcome as well. Now that we have more cost-effective liquid embolics, it’s being considered and we’re open to it. And obviously that landscape has changed quite a bit.

Yeah, I agree. I just think we’re in this era where we’ve ramped up costs and now we’re trying to cut back cost a little bit, but we’re farther down the track than we used to be. Let’s move to some more personal questions about embolization. So every operator has a case that has recalibrated them, one that either worked better than expected or there was an adverse outcome. Talk us through a case, and Ram, I’ll start with you where your embolic strategy surprised you, either it worked better than you had thought or it humbled you.

Yeah. I would say it’s a two for one in some ways. One of the interesting cases, one of the first portal vein embolizations I did as a fellow in training, was an attending, relatively early career, who utilized glue. I was amazed at how efficient it was. And so I would say probably one of my most humbling, but also nerving and sometimes very satisfying, is actually that portal vein embolization case.

I tend to be glue first, in that–because I’ve noticed the procedure time. But what I think is the most important in any of these things is–we probably think about it is–we think about the intent, what our goal is. I always analyze the flows, and the anatomy, and the variants. And I think the tenacity of flow, it’s almost like a running river in the portal vein. So you have to make sure that is done in a very methodical and a safely parked way.

So for me, it’s very nerving. I feel my pulse is trending when I am injecting glue for the very first time in that portal vein case, making sure it doesn’t go into some other unexpected area. And, you know, what are my safety wires? I may actually even put up a balloon to exclude a certain branch so that I don’t risk non-targeted embolization. So I would say I have the thrill, the stress, but also the, “Oh, that was great. We got it done.” And of course, making sure you didn’t glue in your catheter.

Well, I have an interesting case with that, and–Nevin, if you don’t mind me going on this one next.

Yeah, please.

I was doing a thoracic duct embolization and, you know, those cases–for anyone that’s ever done a thoracic duct embolization, these cases are–they’re the worst, right? They’re the types of cases sometimes where you’re waiting for that Lipiodol to travel up. You’re like, “What in my life led me to this position, where I’m doing this type of case and I’m sitting here for hours waiting for the Lipiodol to travel up?” Well, so this was–we got the Lipiodol up, the thoracic duct was opacified, we were able to access it. We got our wire in there, we got our microcatheter in, and I put a couple coils in. But then I also used glue, with the coils as a backstop, and I glued my microcatheter in. Glued it in. And I thought I’d done everything as I was supposed to, but something didn’t go right. So I essentially had to just yank the microcatheter–

Yeah.

–and luckily it broke off in the thoracic duct. There was no major pieces sticking through into the IVC or the aorta or anything, you know, any serious structure, but that case definitely–it humbled me. Because it made me realize, okay, you may be doing all these glue cases and you think you know what you’re doing, but sometimes things just don’t go the way you plan. So that’s my fun glue story. Nevin, have you had any cases to where you feel like, “This case humbled me,” or, “This worked better than I thought it did, it would. We saved a patient”? Tell me about your experience.

For sure. I mean, I’m still waiting to glue my first catheter and I think that’s–It’s always funny when you’re learning glue, right? You’d have the trainees like, “By the way, you can glue a catheter and please don’t ever do that. And now good luck using glue.” And obviously everyone’s heart rate’s just jumping. And I will say, yeah, portal vein embos are one of my favorite cases. There’s nothing more riveting than watching that glue cast form in the portal vein. It’s like one of the most beautiful things you can see in medicine.

No, I think we always learn from things that don’t go well. I got a case–it revolves around a case I wish I’d used glue. It was a young gal who had a chest tube injury, one of these intercostal ones. I don’t know if you guys deal with a lot of intercostals, but they’re probably my least favorite cases because they’re so robust in terms of the collateral supply. And I was a bit earlier on in my career and got decent purchase, but the intercostal anatomy was really tricky. I couldn’t get back door, the thing was transected. And I think in that case, I was still kind of young in my career, was worried about things like gluing in catheters and stuff like that. So I went with sort of a gel foam and a coil situation, tried to use that to get the distal penetration and some long-term. And I think I brought that patient back again early that night, the next morning, for a take back because they were still bleeding and ultimately needed a surgical exploration to stop the bleeding.

So that’s one where you learn the limitations of certain things and sometimes there is a really good–And glue does have trade-offs, right? You’re a little bit more scared, a little more stressed, but if you can get that great distal penetration it has a really good efficacy at stopping bleeding, especially in patients when their clotting factors are getting depleted and whatnot. So yeah, that’s a case I’ve learned from. And as a result, I’ve tried to put a lot more glue into my practice.

I think that this just goes to the point that we are all shifting in the way we approach these cases, and we’re all taking a multi-hybrid approach to embolic materials, which you both have eloquently put. One of the questions that I get from a lot of trainees–well, in the private world, I don’t get this as much anymore, but I’m sure you guys get this, is how do you know that you are done with the case? What’s a good endpoint for embolization look like to you and how do you communicate that threshold to a trainee?

Great question. I think it just takes a repetition of different clinical scenarios and different intent in what the goal is. For example, being at a trauma center, I sometimes will have a patient that has two organs that is bleeding actively. It could be a spleen and a liver or a kidney and a liver. And so sometimes it’s about how do we manage time for the case, meaning time and protecting the patient from bleeding? There are scenarios where I’ll go in and I’ll shoot a bunch of gel foam in one of the organs, particularly, maybe the spleen, and then make my way for subselection into the liver so I can then be a little bit more precise in which segments, arterial branches, that I am embolizing.

So it’s hard to just preemptively script this. I think it’s–for all of us, right?–we’ve had repetitions. And even in board review, you could say all the things–and we’ve been to boards–but being in the moment of how you actually manage, deduce your time and energy, so that you can appropriately shift and, you know, go from one area to another, is extremely important.

Yeah. I think it depends on your clinical vignette, right? So that comes back to sort of what organ system. For a trauma, something like that, where it’s a patient who’s had a horrible liver laceration, sometimes I’ll just do glue because I know this patient’s getting re-scanned, or this patient’s got other injuries, and so I don’t want to have that call from the surgeon at 2:00 in the morning, being like, “Well, did your surgery get it? Is there any chance they’ve bled through this coil pack or this gel foam?”

If you’re talking about particles–I don’t know if people are still using the, how many beats of stagnant contrast column. So that’s another consideration. And coils too, if you’re coiling an organ for bleeding, you don’t want to see some collaterals, you don’t want to see that end organ. But like you get into something like a vascular malformation case, that’s a totally different beast, right? You’re trying to nuke a nidus, not an endpoint. And so you got to tailor your endpoint to whatever case it is, and it comes from experience and, you know, usually it’s from the times where you wish you had done a bit more and then you get punished later. That’s how I’ve learned the most in my career.

Yeah, I completely agree with the both of you. I think clinical scenario definitely matters. It’s an impossible question, almost. The only thing I can say is that if you’re in an acute situation, for trainees, I always say, “Keep an eye on the vital signs. Sometimes if you have a GI bleed or some sort of trauma, you will see a reversal or an improvement in vital signs. Maybe the patient’s on less pressors after you embolize. Maybe the tachycardia improves, the pressures are not as soft. So always keep the patient’s clinical situation in the back of your mind when you are embolizing.”

Okay. We’ve covered a lot of ground here. We’re going to zoom out now. We’re going to talk forest perspective, the next 10 to 20 years. Where do you both think that embolization is headed? Is there any role for AI in embolization? What does the landscape look like to you both?

Only if we could really all see into the future.

Right.

I have a little bit of an informatics and IT background, formal training, but also some of the roles I’ve had in the hospital. I think there are some values and utilizations of AI and all that, but that’s very generic. So for example, scenarios that I think about in utilization is could we have CT that helps us capture the initial diagnostic imaging that gives us a sense of the distribution in a better way so that we can maybe highlight which areas to target first versus second? I think also taking in mind the clinical dynamics of when to intervene, how severely to shut down flow. I think these are all theoretical things. I personally think there is human engagement that will have to teach these models and such, but I’m curious, to be honest with you.

I live in this space in a very deep way. I’m honestly not sure, because I’ve seen every 10 months or so, the evolution of technologies in what we can and what we can’t do. So I’m impressed by that as well. So I’m sorry I’m a little bit non–generic here, but I’m curious as to what’s coming. I think there is some utilization, but the one benefit we have is we’re a very hands-on specialty.

And how about you, Nevin?

Yeah, I feel like it’s two parts. The AI thing is always an interesting question and I’ve sat there in lectures and said, “Okay, how do I incorporate this AI thing into my IR practice? How’s that going to help me in the middle of a case or planning?” The only signal I’ve seen is, I think the cardiology world’s got a lot of interesting stuff going on with the FFR for estimating stenosis, both from invasive and non-invasive imaging. There’s some AI programs related to that to generate in the data sets. So if you can empower an interventional radiologist before they even go into a case to have a slightly better understanding of, “What’s the level of stenosis, how hard is this going to be to shut down? Is there going to be extra velocity?” Any extra data points that AI can generate for the clinician before they go in, I think is going to improve patient outcomes, improve the procedure times. I think that’ll be a really useful tool to harness. So in my mind, it’s mostly before the case, as opposed to during.

And then in terms of a technology aspect, I mean, you’ve referenced at the beginning of the podcast here, right? In the last 10 years, it’s gone from zero to 60, and so I can only imagine the amount of customizable, or the added, toolkits. We get smaller microcatheters, more trackable coils, more function, more bells and whistles on some of either the coils or the embolics. So I can only imagine the type of tools we’ll have access to that will allow us to be more subselective, do a little bit more with less downside, minimize that risk of things like non-target embolization, and hopefully bring down costs. But I also imagine more technology would also increase the price of some of these things too, potentially. So we’ll have to balance that.

Well, and two parts from my perspective as well. Some of the things that I feel like are probably going to come down the pipeline are resorbable embolics, things that are resorbing over time. I’d love to see some more of that. I know that things are in the works for some of this. So that’ll be an interesting piece for the embolization portion of it. But for AI, I think what’s really interesting is the conversation that the three of us are having about AI is, “How is it going to enhance our ability to function,” as opposed to if this conversation was with three diagnostic radiologists, the question is going to be–it often centers around–”Is AI going to take my job?”

And I feel like we are in such a good position to potentially utilize AI for things like you’re saying, Nevin, and like you’re saying, Ram, “How can we make ourselves more efficient in the IR lab?” And it’ll just be interesting to see. And fortunately, we’re going to be able to witness this in our lifetime. We are going to see a complete evolution of the field and I’m excited for it.

No, definitely, it’s an augmenting role. I don’t think, honestly, in any of the specialties it’s a replacement role. I think that’s where our value to patients and our clinical colleagues shows and demonstrates. So having that informatics background, I would emphasize that it’s an augmentary role as opposed to a replacement or such.

Perfect. Well, it looks like we are out of time. We’ve hit our allotted time limit. I want to thank you both for discussing embolization today. It’s been a fantastic, illuminating conversation, and we’ll be running into each other at these meetings in the future, so hopefully in a decade we’ll be able to say, “Hey, this is what’s changed, and these are the things that we got right, and these are the things that we did not get right.” So until next time, thank you again.

Raja, Nevin, thank you so much. Had a wonderful time, and thank you to our colleagues at Cook for helping us put this on.

Thanks for having this, guys. Absolute pleasure. And enjoy your time in Canada.

Hey, thank you.