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BackTable / VI / Podcast / Transcript #321
Podcast Transcript: New Innovations in Lower GI Bleed Embolization
with Dr. Kevin Henseler
In this episode, host Dr. Aaron Fritts and interventional radiologist Dr. Kevin Henseler discuss his treatment algorithm and new technologies for embolization of GI bleeds. You can read the full transcript below and listen to this episode here on BackTable.com.
Table of Contents
(1) Typical Presentations of GI Bleeds: Upper vs. Lower
(2) Lower GI Bleeds: Relative Contraindications and Considerations
(3) Working Up a Lower GI Bleed: Pre-Procedure Imaging and Planning
(4) Access and Catheter Selection
(5) Artery Selection and Angiography
(6) Ghost Bleed: Tips for Finding the Bleed Intraprocedurally
(7) Intro to Embolization Devices for GI Bleeding
(8) Obsidio: Frontiers in Emerging Embolization Tech
(9) Injectable Solids: The Current State and Future Directions
(10) Closure and Post-Procedure Care
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[Dr. Aaron Fritts]
Today, we have another very special episode, we're going to be talking about treatment algorithms and new technologies for GI bleed embolization. We've covered this topic in the past, you guys the audience probably remembers prior episodes with Sabeen Dhand, Michael Barraza, and with Don Garbett where we've discussed different techniques and tips and tricks on GI bleeds and people's different approaches. Today, I've got a special guest, Dr. Kevin Henseler who's also going to be talking about new innovations in the embolization space but we're also going to get into his algorithm on how he approaches GI bleeds. Kevin, welcome to the show.
[Dr. Kevin Henseler]
Thanks, Aaron. It's good to be here.
[Dr. Aaron Fritts]
First thing we'd like to start out with just for our audience is tell us where you're at, what your practice looks like, and maybe a little bit of background about yourself.
[Dr. Kevin Henseler]
I date myself by saying my training was at the turn of the century. I did my residency at the University of Wisconsin, I'm a proud Badger and grew up in Wisconsin. Then fellowship at Johns Hopkins, and then started practice in Minneapolis St. Paul right out of fellowship in 2003 so it's been 20 years. In that 20 years, we have like is happening in all of healthcare, we're becoming bigger and bigger.
We started out as a small boutique practice that has gotten bigger and bigger and right now I'm part of the Midwest Radiology which is 170 or so radiologists. We have-
[Dr. Aaron Fritts]
Wow.
[Dr. Kevin Henseler]
-about 16 interventionalists plus or minus. Right now we're down with one of our partners moved to the diagnostic, we have three new partners coming on at the end of their fellowship year. At that point, we'll be at about 17. We cover four bigger hospitals and four smaller hospitals and so we were in quadrants. Four of us cover a big and a small hospital generally. The good thing about the size of our group and our interventional group is that we're now at the size where we're going to likely be experimenting with an evening shift.
We will have a dedicated interventionalist at five o'clock who will work from five to two and take care of most of what comes through during those times. As an old guy, I'm excited about getting some call relief.
[Dr. Aaron Fritts]
Kevin, that's funny. I didn't realize when we first spoke that's how big your group is. My old group which I still cover for locums is Texas Radiology Associates and they're I think around 140, 150 general rads and they have around I think 16 IR so very similar in size. Every group in Texas boasts to be one of the biggest in the country and everything but sounds like you guys have them beat. There's three really big groups in Texas, two of which are in Dallas I think one in Austin and so I didn't realize how big you were.
Actually Texas Radiology Associates I think the last year they switched to that night float system that you're talking about and they seem much happier because back when I was covering call it was 24/7 that is a beat down through a week and a weekend as you know.
[Dr. Kevin Henseler]
Well, as you can imagine being a Midwest group, we are a bit quieter than the Texas group. It's about trumpeting how large we are but we're a very large group. We are very much looking forward to testing this evening shift and seeing how it goes. Because of the complexity of covering so many hospitals, it's really not a slam dunk, it would be different if it was one or two really big hospitals is all you covered. Because we've had a big geography that we cover, it'll be a challenge but we're really looking forward to seeing if we can make it work and we got a great group of people that we're working with.
(1) Typical Presentations of GI Bleeds: Upper vs. Lower
[Dr. Aaron Fritts]
As a fellow Midwestern, I'm from Ohio, we're not as boastful as the Texans except when it comes to college football. Maybe we rival in that case. Well, let's jump into it. Let's talk about GI bleeds. Speaking of call, how do these patients typically present in your practice? For our trainees in the audience, what are the typical causes? We're going to talk more about the lower GI bleed state but what do you see more of in your practice upper versus lower?
[Dr. Kevin Henseler]
We see more lower GI bleeds. We're certainly asked to consult on lower GI bleeds more often as we'll probably get into the number of interventions versus consults in lower GI bleed is less than in upper GI bleed. When they call us the percentage of people that we're actually going to do something on is very high. When we see those upper GI bleeds, obviously, you can look at those as either variceal or non-variceal. Talking about the non-variceal bleeds, clearly, the duodenal ulcers are the number one things that we're going to see and we see that with some regularity.
The interesting thing about the upper GI bleeds is that those tend to actually be real emergencies. Those people are crashing by the time you're seeing them. They've had their endoscopy, they've all had endoscopy first, and the endoscopist either is calling you from the endoscopy suite saying we really need your help or had sculpted them a few hours earlier and put some clips on and now they're just bleeding again. Those tend to be a much more emergent case and it's very satisfying. One of the things I think that we should keep in mind is those are great cases because you really are, in some cases saving people's lives.
The endoscopist have all kinds of cool tools just like we do and they're getting more and more cool tools and so when you grumble about getting the upper GI bleed call in the middle of the night, be glad that you can be there for that patient. It may be not too far in the future that we do that less and less as the endoscopists have more and more things to do. Those are pretty straightforward. You're going to get your celiac access I think as you've said, you've talked about the techniques on that. The pearls of wisdom I would give is obviously it's important to get past the bleeding source.
When we're doing upper GI bleeds, don't forget that you're going to get back bleeding through that pancreatic duodenal arcade so don't be happy just to see the bleeding and get a coil in that area and make sure you get dispel to that. I'm coiling all lows and we're coiling presumptively whether we see bleeding or not, partly because it's the right thing to do. I think the data shows that even if you don't see the bleeding, you have the same outcome positive outcomes if you do see the bleeding.
Also, you want to get in there and get your coils in there because if the patient continues to bleed, there's some satisfaction in being able to say, "We've done everything now it's going to be somebody else's turn," as opposed to having you go back in and do the angiograms which I think happens very rarely.
[Dr. Aaron Fritts]
You're talking about coiling across the bleeds, typically, especially with the GDA. I was just thinking about that. That tends to be probably the biggest coil pack you leave for a GI bleed wouldn't you say?
[Dr. Kevin Henseler]
Yes, and it's interesting because that GDA can be a very big vessel and usually is a very big vessel but as you know, when you see active bleeding, often that vessel is very spasm, and you can barely even see what's going on. You get your catheter in there and you've got to dug in the vessel before you actually find the bleeding. That always makes me concerned when I see that because I know that that vessel is going to relax, and you pack your coils in there. As soon as that vessel relaxes you aren't going to refinalize that.
I think that's why upper GI bleeding has a much higher re-bleed rate and reintervention rate than, for instance, lower GI bleeding. I think that's just something to keep in mind that as long as you can safely get those coils and put as much metal in there as you can because things are going to relax and they're going to change and remodel. That ulcer is still going to be at risk of bleeding even after you high-five your tech because you think you're done.
[Dr. Aaron Fritts]
Well speaking of that, I want to get into one quick tip for anybody new out there is because you're trying to get as many coils packed in that GDA as possible, do you tend to use detachables in that spot so that you can really pack them in right to the very edge of the hepatic?
[Dr. Kevin Henseler]
Yes, absolutely. Unfortunately, nowadays I'm so used to the detachables and they are so secure that I tend to use detachables for almost everything. I know they're very expensive and I was at GEST last year and there was a panel of old guys my age who shook their heads and said the same thing which is they know that they really just should do that pushable coils because they're so much cheaper and they're easier and you're going to get it, but the techs are just happy to hand you that detachable coil. Certainly for trainees, for new people, they probably don't have as much experience with pushable, and when you first come out, don't make any mistakes.
Don't worry about the money, don't worry about how much your equipment cost, don't worry about how many catheters end up on the floor. Just do the right thing for the patient and make sure that you're doing it safely.
(2) Lower GI Bleeds: Relative Contraindications and Considerations
[Dr. Aaron Fritts]
I totally agree. All right. Well, let's move on to the lower GI bleeds. Are there any contraindications to angio and embolization if somebody's got real failures might go-- Clearly, if the patients really bleeding out, it's a dire situation. It's a life and death situation, you're proceeding, but is there any kind of contraindication that people should be looking out for before you just take them angio suite?
[Dr. Kevin Henseler]
I would say that those are all relative contraindications. Certainly having an elevated creatinine, renal failure, renal insufficiency is relative in these cases as we talked about. These are generally patients who are really crashing. If they need dialysis after you saved their life, and that's just fine. Contrast allergy, these days I give them a dose of steroids before they come down and consider that covered, and so that's not particularly anything that I'm concerned about.
Again, relative contraindications, one of the thing that I do worry about is when we're asked to embolize a surgical anastomosis. It's not uncommon that people will have gastric bypass and get ulcers at the anastomosis, and they will have looked at them endoscopically and they'll tell you, this is where the ulcer is. I tend to have a very long discussion with the GI and surgery team before I would embolize an anastomosis. With the number of patients especially in the Midwest to have gastric surgery bypass, sleeve, any of those things. I think that is one of the things you got to be very careful about.
(3) Working Up a Lower GI Bleed: Pre-Procedure Imaging and Planning
[Dr. Aaron Fritts]
It's funny, Kevin, you mention that because I had that case last week come across our plate in one of the Dallas hospitals I work at, and we decided to go conservative. Watch and wait, and thankfully the patient stabilized, but the GI doc was pushing for us to do an angio. We end up doing a CTA and the CTA was negative, and we said, "Let's just watch the H and H overnight and see how she does." Thankfully, she did fine. My next question is, in your workup, walk us through your lower GI embo workup pre-procedure imaging, are you pushing for a CTA? Does it depend on the time of day?
[Dr. Kevin Henseler]
When I think about lower GI bleeds, again, this tend to be patients that are generally more hemodynamically stable. They're often patients who have had a scope or who come into the ER, and have had some bloody stools and maybe have some soft vital signs. In those cases, I really do want to get a CTA because I think it's really important that I know the vascular territory because often your first couple of angio runs, you're not going to see the bleed. If you know where to go, you can get your catheter out much further.
For me what I like to do is a much more aggressive hand injection, and I will often blow whatever clot there was that kept me from seeing the bleeding away if I know where it is. In our practice, almost everyone in the lower GI bleed is going to get a CTA. I can't think of many reasons even if they're crashing. Our IR suite is next to the CT scanner and the extra five minutes it takes to get that information really probably saves me three times that in trying to sub-select.
[Dr. Aaron Fritts]
That's true.
[Dr. Kevin Henseler]
For my standpoint, the CTA is important. I think one of the things that is important, again, a pearl that I would give is the custody of information is really important in these cases because you'll often get a call from the GI PA who will say, "Yes, this person is bleeding." The nurse called and said, "They're bleeding." We've scoped them and we couldn't find a bleeding. When you actually talk to the closest person to the patient which is often the nurse, they'll say, "Yes, they had some bloody stools three hours ago, like 4:00 AM." It's hand-off in nursing rounds and it's 8:00 AM and they get that, and so then they call the GI service and say, "He's bleeding overnight."
I think one of the things to do is to always be sure what the value of the information you're getting because sometimes it's very old information. The other thing I like about the CTA is that, for me, if the CTA is negative, I'm not doing an angio because I think the overall likelihood of a positive angiogram is going to be very, very small. The difficulty with that is when they have GI bleeding, you get the CTA. If it's negative, and then the next day they're bleeding again, then what do you do? You keep on getting the CTAs. Do you just say, "I'm just going to do the angio and try to figure out what's going on." I think that's on a per-patient basis that you-- Depends upon the time of the day where things are.
I think the CTA is incredibly valuable, and I think there would be very rare instances that I didn't use all the information I could possibly get, and that's a really valuable piece of information.
[Dr. Aaron Fritts]
The tricky thing for me with the CTA is that you get the CTA, and it will be negative, and then the GI doc still stops by, the department's like, "Hey, they're still bleeding." It might even be right after the CTA. You're like, "I don't see anything." So you don't know. Was that just a little blood that was in their bowel that they just pooped out for the CTA.
That's where it gets tricky and that's where we tend to say, "Okay, let's do another H and H. Let's trend it. As long as their vital signs are stable, let's just wait and watch."
That was the case with that case I was talking about last week is the GI doc was really pushing us to do something and we're like, "It's a surgical anastomosis. We don't want to embolize unless we absolutely have to."
(4) Access and Catheter Selection
[Dr. Kevin Henseler]
I think one of the other things that I think we should keep in mind is that we should be treating patients, not images. We always hear that in training, but there's positive CTAs that are subtle for bleeding that I have found over the last five years that CT has gotten really, really good. That even when I see a positive bleed and I know exactly where the vessel is, there's 50%, 25% of the time I go in there and I still don't see the bleed because the CT is so sensitive. We have to remember that whatever it is, 80% or 90% of these GI bleeds are going to stop on their own.
If the patient's really doing well and even if the CT scan is positive, sometimes you say, "Let's just watch things and if they continue to bleed, I've got a source and I'll definitely go in." If the patient's doing well, clinically stable, we know that there's some bleeding, but we knew there is bleeding because they're popping blood. We know there's some bleeding and we have a target if we need to. Let's wait to see if this will resolve itself versus me going in and flailing around.
The other thing that I think is helpful from a pearl's standpoint is, at least for me, for most of these, I'm going to use a Glide Sim catheter. I can get that Glide Sim catheter all into the ileocolic artery if I want to. I can get it really, really far out, and getting a 5 French catheter really far out gets you a really, really good injection. If you can't do that, then a larger microcatheter because I think it's really critical that you distend that vessel that is the target vessel because you're going to miss the bleed if you're not giving that a relatively aggressive injection.
[Dr. Aaron Fritts]
That was my next question is approach. It sounds like if you're using a Sim, then it's probably femoral.
[Dr. Kevin Henseler]
Correct.
[Dr. Aaron Fritts]
Are you ever doing radial approach for GI bleeds?
[Dr. Kevin Henseler]
Not really. The way that I look at it, first of all, I don't do a lot of PVD in my practice. I think you got to do enough radial access that you're good at it, and I have in an awful lot of experience in the groin and not as much in the wrist, and so I'm just as comfortable in the groin than the wrist. Now, you appear something like that, wrist access may be something to consider. In these patients, they're flailing around. I don't see that as a great case for a wrist unless you are incredibly-- If you're really, really fast eye with radial access, you go at it. Again, if you're new, these patients tend not to be cooperating very well. I think that groin access is just fine.
[Dr. Aaron Fritts]
Yes. That tends to be the case. The people I know who approach this with radial are people who-- That was just part of their training. They did a lot of radial – like, Sinai or some place like that, and so they're just as comfortable with radial as they are with femoral. I'm not because I didn't do a lot of radial in training. Like you said, femoral is how I'm use to done pretty much every GI bleed femoral. It wouldn't make any sense for me to go radial unless there was just such a crazy angle. I couldn't get anything, and the patient's really dire straits. Then I might try it from above.
You mentioned your catheter of choice. You said Glidewire as well? Is that what you're typically using to get access?
[Dr. Kevin Henseler]
I would start with the Bentson just to get into the vessel and get it engaged, and then I would get my Glidewire quite a ways out into the vascular arcade so that I can get my as distal as I think I need it to be.
(5) Artery Selection and Angiography
[Dr. Aaron Fritts]
Yes, so assuming that you know where the source is, it's a SMA territory. Let's say you accidentally pop an IMA, are you going to do an IMA run if you know it's SMA territory on the CTA?
[Dr. Kevin Henseler]
That's a good question. It depends upon which way the coin flips whether it's a head or a tail. If I see the bleed on CT and it's an SMA bleed, and I find the bleed and I embolize it. The textbook would tell you, "Well, you still need to do your celiac and your IMA run." Sometimes I forget to read the textbook and I might just say that's fine. If it slips into the IMA, absolutely. I'm going to do that without a question, or if I'm concerned or there's been something else going on with a patient that makes me think that we should check for something else. Generally, my rule of thumb is get out of the vessel as soon as you can. I don't like screwing around inside the vessels.
The next thing you're going to do is you're going to dissect the IMA trying to get into it, and you haven't done anybody any good.
[Dr. Aaron Fritts]
Even worse.
[Dr. Kevin Henseler]
Right, so I tend to try to minimize the time that I spend in the vessels, and generally wouldn't as a matter of course look at every single vessel unless there's an indication.
[Dr. Aaron Fritts]
I totally agree. As you know, most of these patients with the lower GI bleeds are elderly and their IMA is minuscule or just completely occluded already. It just doesn't make it sense even to try because on the CTA, it doesn't look like you are going to get in with any catheter especially if you see it on the SMA and like you said, it's coiled is done like should just get out of there, I think.
[Dr. Kevin Henseler]
One of the things I think that you bring up is also don't underestimate the value of that CTA. Sometimes, especially when it's two in the morning, you're at home, you turn on your computer, you see the bleed, you call your team, you go in and you can forget to look what the iliacs look like. What does the femoral look like? Which side are you going to be going on? Is there a replaced right hepatic? If you're doing, if you're going to do a middle colic embolization so that you know where your anatomy is.
Certainly, take time to look at those other things. Don't just say, "Okay, there's a positive GI bleed, I'm going to go in," because you can end up wishing you had spent 30 seconds reviewing everything before you go in.
[Dr. Aaron Fritts]
Like you said, the CTA is a diagnostic exam that you just got 30 minutes before. If there's no bleed in the IMA distribution, then why are you mucking around with it? Just because we are trained that way or hardware that way. From training, it doesn't make any sense practically and it can hurt the patient.
[Dr. Kevin Henseler]
I would even say that part of that is that when I trained, you had to look at all those vessels because we didn't have. We had to find the bleeding and so you weren't ever sure where the bleeding was, so you had to find anything. Now it's a different world.
[Dr. Aaron Fritts]
Real quick question, what is your typical injection rate for the SMA?
[Dr. Kevin Henseler]
I do hand injections for all of these. Again, it's a time in the vessel. I feel very comfortable doing that. I can control it so I'm not stepping out and doing power injections.
[Dr. Aaron Fritts]
Got it. Are you trying to get them to hold their breath to reduce that respiratory motion?
[Dr. Kevin Henseler]
Actually, generally not. I think that holding their breath, they tend to move around more when they're holding their breath, and then halfway through your run, they take a big huge breath out, and then you've screwed. I just let them be who they are, especially when they're under some sedation. They're generally not taking really big deep breaths. I think another thing that trainees can always remember is glucagon is your friend, if especially big GI bleeds, there often is hypermobility of the bowel. If you need to give a little bit of glucagon, I think that's just as helpful as trying to do breath holds and then you've got that bowel at least reasonably hexed in place for a few minutes as you're doing some runs.
Again, I'm a minimalist from that standpoint and try to just let the patient breathe shallow breaths like they're doing normally.
[Dr. Aaron Fritts]
That's a good tip. That's a great tip.
[Dr. Kevin Henseler]
To end that is also always remember looking at these runs. Look at them subtracted and unsubtracted. Every single one of these runs you should be looking at both of them just to make sure you're not getting faked out and also that you're not missing anything.
[Dr. Aaron Fritts]
On that, we've talked about this before in the show. I was always trained to take your gloves off, go out and sit down in the control room and look at the proper images instead of trying to stand there and look through your fogged-up glasses. I know you mentioned that you like to make it speedy. Let's keep the case going, get it in and out as fast as possible. What's your take on that?
[Dr. Kevin Henseler]
My take is, my advice would be that before you are done, you should take your gloves off and look at everything. Especially if you've had a negative angiogram. I think that's important. I'm doing everything in the suite. I'm not taking my gloves off and I'm not going back and looking. I think the other thing that again is a pearl for trainees is you often have people standing next to you who have been doing this for 20 years. I always say, does anyone see anything? 75% of the time people will say, "Hey, yes, yes, I see something." You're like, "Okay, no, that's not that, that's something different."
Then you're looking at it and you're walking through it and you're making sure that that's in fact not it, but 25% or 10% of the time someone's going to say, "I see that." You look at it and you're like, "Oh yes, maybe that is something and you might do another obliquity or do something else." It's a good time to be humble when you're in these cases and ask for help. Your techs have lots of experience and they're not perfect and they don't have the knowledge base that you have, but they have eyeballs and experience and so use that.
(6) Ghost Bleed: Tips for Finding the Bleed Intraprocedurally
[Dr. Aaron Fritts]
Yes, you're right. They have seen many of GI bleeds, sometimes they've seen a lot more than you have and it is good to have, like you said, an extra pair of eyeballs looking through those images. What happens if you don't see a bleed? Do you ever do anything provocative? We've done episodes talking about that before. I know it's a new thing, but–
[Dr. Kevin Henseler]
I would be on the wimpy end of that spectrum. I'm certainly not going to put TPA in heparin. I would consider in situations and I've done it a couple of times, I like it because you can reverse it if you need to or if all of a sudden you've got five bleeding sources and you're getting overwhelmed. One thing that I think is helpful is nitroglycerin. These vessels often are again, have vasospasm when they're bleeding. If you have a negative and you really know where it is, so nitroglycerin could go a long way to opening the vessel and seeing that bleed. That's a fairly low-risk medication to be giving a patient and that's as long as their pressures are okay.
[Dr. Aaron Fritts]
Yes, with a short half-life. Yes, that I'm on the whimpy side too. I can't go do what Sabeen does with the TPA and everything. It just nitros as far as I've gone and I think I agree with you, it should help open up those vessels. Only in the case where the CTA shows, there's something in that area that I'd be like, "Okay, let's put some nitro in here," and especially if they're hypertensive, those vessels are going to clamp down.
[Dr. Kevin Henseler]
One of the things also I think when you having that calculus is where are you? Because a lot of these, oh, I'd like to say you bloom where you grow. I'm in a outer-rim hospital that's a pretty good size. It's almost 500-bed hospital. Our general surgeons are good, but they don't want this patient crashing because you gave them TPA and you can't control the bleeding or there's multiple sources and you're going to burn bridges doing that.
Whereas if you're in an academic center and you've got the chief surgical resident sitting outside the window and giving you the thumbs up to do that, that's just a completely different place to do it. You've got to be careful where you are and what support you have and you don't want to be a cowboy and then have a bunch of people look at you and say, "Look what you made me do. I know I had to open this guy's belly and I don't know where the bleeding is and I'm going to do a hemicolectomy and he's going to get an ostomy and you haven't really helped anybody."
(7) Intro to Embolization Devices for GI Bleeding
[Dr. Aaron Fritts]
All good points. All good points. Let's get into the meat of it in terms of embolization devices, we've talked a fair amount previously on the show about detachable coils. We've talked about glue, actually Ziv Haskal was on the show talking about glue and you're going to help talk about new product that's soon to be on the market, but at first before we get into the new stuff, I want you to tell me what's been your traditional go-to embolization device for lower GI bleeds?
[Dr. Kevin Henseler]
Clearly coils. You hear or you see some research about particles which makes me cringe because I'm just so concerned about end-organ damage of the colon and causing ischemia. For me, it's always coils. Glue, I'm not a gluer, it's interesting when I went through fellowship, that was the time where people were gluing catheters in place and so glue was very, very high risk. We just didn't do very much glue. I think as Ziv said, I listened to that, if you have any desire to do glue, you should, by all means, listen to it. I must listen. I think he's right. It's not to be trifled with.
If you have glue in your training and you are very comfortable with glue, I would work hard to keep that skill set up because once you lose it or if you didn't get it, getting the experience with glue is a very, very tough road. If you've got it, try to keep it. If you don't have it, you got to be careful about trying to learn with glue because it's very operator dependent. There's a lot of variability. What dilution am I going to use? Am I going to have glue stuck on the end of the catheter that's going to embolize, God forbid am I going to glue my catheter in place? I tend not to use glue. For me, a lower GI bleed is a coil, a coil, and a coil. That's really all I'm going to use.
[Dr. Aaron Fritts]
Detachable, like you said before with the upper GI.
[Dr. Kevin Henseler]
Although there are times where when you are, if you can get very, very far out into the vasa recta, I'll put in just like a–
[Dr. Aaron Fritts]
Two millimeter Hilal or something.
[Dr. Kevin Henseler]
Two millimeters straight coil. Those are great cases and you're done and you're out.
[Dr. Aaron Fritts]
I love those, those are my favorite, those little and you can just shoot them in with a little syringe. Let's talk a little bit about this new embolization product that's coming on the market here shortly called Obsidio. Just give our audience a little bit of background about the product and how you became involved with it.
(8) Obsidio: Frontiers in Emerging Embolization Tech
[Dr. Kevin Henseler]
I live in Minneapolis, which is the headquarters of lots of endovascular companies, Medtronic, Boston Scientific, has a big presence here. One of the opportunities here is to be able to partner with industry a little bit and help them with work. We also have one of the largest animal labs in the country in Minneapolis. I dabble in some preclinical work doing animal labs.
I was doing some work and was evaluating this product and it was part of a group of products I was evaluating. The CEO after we were done reached out to me and said, "I'm looking for some help in continuing to formulate this product and working with it. Would you be willing to do that?" I said, "Yes, of course." It was a product that was already formed but needed some tweaking. We did iterations where you talk about glue, glue is adhesive, it's sticking to things. Obsidio is an injectable solid and I will maybe get into that a little bit more, but it's more cohesive. It sticks to itself. We would go through iterations saying this isn't sticking enough to itself or this has now become too sticky too.
We work through iterations of that. Then I ended up working with the preclinical and FDA approval process, getting all the animal research for the indications of hemorrhage and hypervascular tumor. Have quite a bit of probably have injected it in several hundred arteries. The company was purchased by Boston Scientific and Boston Scientific, I believe, intends to have the market launch of the product fairly soon. That's my background with it.
What is it? Obsidio is not a liquid embolic. When we've been talking about glue, we're talking about liquid embolic. When we talk about Onyx, we're talking about a liquid embolic. With Obsidio, it's an injectable solid. What it is, it's like peanut butter in a 1cc syringe. It's very, very thick and viscous. When put under pressure, it flows like a liquid. It can go through a small microcatheter. Then once it exits the microcatheter, it moves back to that solid state.
The physical properties of Obsidio are such that it is not going to flow very, very distally like a dilute glue would. It would function much more like a more thick viscous glue material. It's going to generally stay near the tip of the catheter. If there's a high-flow vessel, some of it will shear off, it will go distally, or if you're injecting it very, very slowly, you can have the blood supply move it very distally and fill up an entire vascular bed.
[Dr. Aaron Fritts]
It reminds me of cement with kyphoplasties. Just the way you're describing it, PMMA, it's got that toothpaste-y consistency.
[Dr. Kevin Henseler]
Exactly. You'll inject it when you see it, when your rep comes and shows it to you, you'll put it on your finger and it's just like that. It's like that toothpaste or peanut butter, very, very viscous, thick material. The genius of it is that biomechanical ability to have it flow and be a fluid when it's under pressure in your microcatheter.
[Dr. Aaron Fritts]
Got it.
[Dr. Kevin Henseler]
What that means is that it's very controllable because as soon as you stop adding the pressure, then everything stops, everything is in place. There's no adhesion, so it could sit in your catheter for as long as you wanted to do, and then you can continue the embolization. One of the things that I think is interesting about the material and exciting is that we just talked a little bit about glue and about the high risk but high reward of glue and how much you have to be really well trained in it because bad things can happen.
I think that Obsidio is a product that de-risks that a little bit where it's going to be something that people after two or three times using it are going to start to feel pretty comfortable with how it works and when they're going to use it. Lower GI bleed, we like to think about this in a smaller vascular bed, maybe vessels less than 3 millimeters. I think it's going to be a great product in GI bleeds and a lower GI bleed. It is catheter agnostic, which is nice. One of the things that's a little bit frustrating is some of the detatchable coils they use, you're supposed to use the product's designed catheter, and that's not always the catheter you want to use. That's another advantage.
There's some real advantages, and I think in these situations, we're going to learn more. It's not just Obsidio, there's going to be a lot more coming out. There's a lot coming out in the liquid embolic market. I just said, Obsidio is not a liquid embolic, but in that whole market basket, a lot is coming out. I think it's going to be really important for everybody, new and old interventional radiologists, to understand what these products do, which products you think you're going to want to invest your time into learning, because let's just say a year from now, there are four or five different materials like this, you can't get good at them all. You're going to have to figure out which ones do you want to invest the time.
I think Obsidio is going to be well-positioned in there. It's got some advantages for coils and that you can be anticoagulated. It's physically filling the vessel lumen. One of the–
[Dr. Aaron Fritts]
Is it permanent?
[Dr. Kevin Henseler]
It is permanent. One of the things that [crosstalk]
[Dr. Aaron Fritts]
Is it radio opaque?
[Dr. Kevin Henseler]
It is. There's tantalum in it. The tantalum is premixed. It's microlyzed tantalum so that you will be able to see it. It is not as dense as Onyx. There's not as much beam hardening artifact. You get a CT and you'll see it in place, but it won't be this big starburst, another advantage. With the anticoagulation, you can use it in anticoagulated patients. As you know, coils really are frustrating in anticoagulated patients, even patients on Plavix and aspirin, which almost all of these patients, not with their lower GI and their upper GI, I believe, they're all on aspirin and Plavix. This is going to help. It may end up being an adjuvant.
You put one coil in, and then you put some Obsidio behind it in an anticoagulated patient, and you've got yourself a very secure embolization.
[Dr. Aaron Fritts]
Sabeen got to pilot actually yesterday and I was messaging with him because I was asking our team of hosts for questions about the new product. Sabeen said, "Really cool game changer." He said, "Very easy to use. They just did a demo on the back table." He was saying, even though it just said multiple times it's not a liquid embolic, he said best of Onyx and best of glue. It takes away the annoying stuff from both of them. He does have specific questions for you. He wanted to know, if there's frank bleeding extrav, like a large bleed, you did mention that this is going for small vessels at this point.
In the animal studies, have you ever seen product extrav into the space or into the GI space when maybe too much is injected or anything like that?
[Dr. Kevin Henseler]
We haven't. Again, because it is cohesive. Even though it will get out to, and I can't quote off-hand into the 30 or 60-micron range, it is not liquid, so it is not going to extravasate out into. Now, if it did, I don't expect that there'd be a problem because we have animal data six months out that just shows that in the vessel there's remodeling and the tantalum is left, and it's a gelatin base and so that all goes away. Even if it did move out into the lumen or out extravascular, I don't think that's an issue. It's an inert ingredient, it's got four ingredients and none of them are toxic in any way, so that shouldn't be an issue.
[Dr. Aaron Fritts]
Does it need to be refrigerated?
[Dr. Kevin Henseler]
Again, that's one of the geniuses of the product and I didn't develop this product, so I'm not taking any credit for that. One of the geniuses of the product-- you just take it off the shelf, they recommend storing it refrigerated. It has a shelf life out of the refrigerator several weeks to months, and they're working on how far out it can be out of the refrigerator. If you have it in your refrigerator in your lab, and you just hold it in your hand and warm it up for 30 seconds, that's really all you need to do, and then it's ready to go. It is in the syringe. It is all mixed up. It is one of the nice things about this in something like a GI bleed.
Some of the other things we've talked about, Onyx clearly is not a great product for this because you've got a huge prep and some of that could happen as you're getting things ready, but probably not terribly practical. Glue, while not taking as long, it is a little bit more fussy when someone's bleeding out. You just have the tech opens the package, they hand it to you, you put it on your catheter, and you're done. One of the things I love about it is you can see it because of tantalum. You know that when it fills the vessel that you've occluded it.
For instance, you've got, let's say, a lumbar artery or a lower GI bleed that you see, you ask your tech for the Obsidio, you put it on your catheter, you fill the vessel, and it might take 0.1 cc to fill a vessel, not often 0.2 ccs. Then you pull your microcatheter out and you're done. We're talking 60 seconds, 90 seconds, less than it takes to prep and get your coils in. It's a really fantastic product with a lot of upside. Downside is that it's sitting inside your microcatheter. Unlike a coil, you're not able to do a run after you have injected this.
Certainly, as we get more and more experience with that, there's no reason that you can't use a sandwich technique in this and put a 0.1 milliliter in and then keep your lumen open. Right now, there's not a lot of data on that. To be on the safe side, you're injecting it. Then, if you've got three or four different spots, that may not be the perfect solution. If you can find the bleeding, it's a great, very quick, and very sure. You take your gloves off, you high-five the techs, and you're out.
[Dr. Aaron Fritts]
I guess you could have a Tuohy on and do an injection to your base, right? If you have your microcatheter.
[Dr. Kevin Henseler]
Yes. Absolutely.
[Dr. Aaron Fritts]
You could do that? Yes, that's really interesting. For example, glue on the Ziv Haskal episode, Ally Baheti, who was the host of that, she pointed out that Ziv suggested portal vein embo for somebody who's just starting out using glue for embolization, what do you think for Obsidio going forward as this product comes to market would be for somebody using it for the first time. Would it be a lower GI bleed in this case, or is there something else that you theorize would be a good first case for new users?
(9) Injectable Solids: The Current State and Future Directions
[Dr. Kevin Henseler]
I think a great first case for Obsidio would be your run-of-the-mill lumbar or inferior epigastric bleed where you have an appropriately sized vessel, you have relatively straightforward anatomy. I think that's the case where you can really see what the material can do in a very safe area. I like it for those-- for small trauma, muscular bleeds, those things. One of the things that I would just caution people with this new product, we talk about vessels less than 3 millimeters or 3 millimeters or less for a reason, and that is this does interact with a wall of the vessel and in vessels that are prone to spasm, you can spasm with this material in.
As you can imagine, as we've talked about, this is like toothpaste. If you have the vessel filled up all the way to its origin and then it spasms, you can spasm the material outside and get some misembolization. When you think about, well, what are the first cases I'm going to do? Those are some of the things that I think you should consider is, how safe is my access? Do I have enough space? I don't want to do this right before a critical branch vessel or anything like that. I think the trauma, the renal traumas, the spontaneous retroperitoneal bleeds, I think those are going to be great first cases for Obsidio.
I'm never sure if I'm right about this, but we talk about a steep learning curve, but I believe that actually a steep learning curve, we think that means that it takes a long time, or it's hard, but a steep learning curve is what you want, which means it's really easy to get up to proficiency. The quicker you can get to proficiency is the steeper your learning curve. I think this is a very steep learning curve. It's going to take you one or two cases, and you're going to go, "Oh, yes. Okay. I got this." Even as you talk about Sabeen, just even at the back table , you're going to get a really good feel about what is this doing. I think that's one of the things that make it very easy to approach as a new product.
[Dr. Aaron Fritts]
Yes. As you were talking, I was thinking about the renal trauma is also a great example, I think, too, because those are typically tend to be small, pseudoaneurysms and you're trying to get real subsegmental as you can. The epigastric, that's a great example, I think too.
[Dr. Kevin Henseler]
As the product has more use and there is limited human data, there's a lot of great lab data, but that's going to come quickly. It's interesting to see, I think that this will be something that people will be really interested for endoleaks. I think there's lots of other things that are off-label. As interventional radiologists, we look at the instructions for use once and then throw them away and forget about them. We will continue to do that, as we have always done, I think there's a lot of interesting uses for the product that will be coming forward.
Again, I think one of the things just to keep in mind is this will not be the only product coming out, there will be others. It's going to be important to figure out where you're going to invest your time, which of all of these new products, you're going to have to decide which products do I think are going to work well in my armamentarium. How am I going to use them? Which ones are the most versatile and the safest and easiest for me to learn? I think that Obsidio ticks a lot of those boxes.
[Dr. Aaron Fritts]
What I've heard is May to June, there's going to be 100 human cases in 30 centers and then a limited market release after that. That's exciting. That's really next month that we're looking at. I imagine yours will be one of those centers.
[Dr. Kevin Henseler]
Yes. Again, I've been able to use it in the lab a lot and feel very, very comfortable with it. I'm excited about the prospects of a new tool in our toolbox. Again, as an old guy like me, learning new tricks is fun.
(10) Closure and Post-Procedure Care
[Dr. Aaron Fritts]
It's fun at any stage, I think. It's what keeps us going. That's why we chose IR. It's always something new, almost every year, it seems like. Well, Kevin, we can talk a little bit about post-procedure care, just to go A to Z with the lower GI bleeds, which are typical post-procedure care for these folks after an embolization.
[Dr. Kevin Henseler]
Generally, post-embolization depending upon their hemodynamic stability and the time of day, I may leave a sheath in if they're unstable, and they don't have an art line and leave a sheath in. If I'm coming in at two in the morning, they're probably relatively sick and so I generally leave the sheath in overnight, make sure that they have monitoring, and have some great access if they need it. Otherwise, I'll close the groin. Again, these patients tend not to be just sitting around quietly. There's a lot of moving and shaking and a lot of changing bedpans. I think in these patients a good closure device du jour, whatever you're comfortable with is good.
Our neuro-interventionalist are using a new device called the Celt device.
[Dr. Aaron Fritts]
Yes, it's hot on the market right now.
[Dr. Kevin Henseler]
I've deployed a couple of those with them. Again, high risk high reward. If it works, it's pretty cool. I'm a little concerned if it doesn't. We close the groin, they're going to head up to the ICU and from my standpoint, our service will round on them, check on how they're doing but nothing specifically that I'm going to do post-procedural care. I'm going to leave that to my medicine colleagues who are much happier to do that than I am.
[Dr. Aaron Fritts]
If not a Celt, is it like a Mynx or Angio-seal, what do you guys like have on the show?
[Dr. Kevin Henseler]
My two favorite, I use the Perclose and I use the StarClose. Those are the two that I tend to use most often and just depends upon the vessel and how it looks. The Perclose is a great device especially if they're on antiplatelets or if they're moving around a lot. I'm feeling pretty comfortable that when I cinch that knot down around my wire and I got nothing coming around it, I'm pretty sure that I'm going to have a good closure. That's really one of the nice things about that. In these, I would tend to probably Perclose them.
[Dr. Aaron Fritts]
Okay. Fantastic. Any final thoughts, Kevin, before we wrap up? There's been a lot of great information.
[Dr. Kevin Henseler]
No, it's been a lot of fun. I appreciate the work you're doing whenever I have to brush up on something that's coming on, whether it's I haven't done a tips in a while or I got varicocele embolization on the schedule, I often go into the BackTable archives and lean on people much smarter than I am. I appreciate the service you're doing and it's a lot of fun to listen to you guys.
[Dr. Aaron Fritts]
Well, thanks, Kevin. It is great that we have these archives now because we look back and it's for over 300 episodes and like, Man." Now the challenge is trying to make that information more accessible so that you're not digging for that content that you really need that day. That's my next sort of stage is trying to figure out a way, some sort of AI algorithm for you to just be like, "Hey, Tips University. Where is it? Bring it up right now?" You're right, we've had so many great people on, some of which we've mentioned today, Ziv Haskal. We just had Fritz Angle talking about adrenal vein sampling last weekend, can't wait for that one to come out.
That's one where you always need a refresher. I don't know people who do that on a weekly basis where it's top of mind. Anytime that case comes up, I need to go over either an article but I like the fact that we have podcasts now that you can listen to on your way to work so works out. Kevin, thank you so much for coming on the show. Appreciate your time and all the intel that you provided. Can't wait to hear more about Obsidio and get our hands on it. If our audience has any questions for you, is there a good way to get in touch with you?
[Dr. Kevin Henseler]
I can leave you an email and I'm on LinkedIn. Those are the two areas to be able to get a hold of me if you have any questions.
[Dr. Aaron Fritts]
Perfect. Thanks, Kevin.
Podcast Contributors
Dr. Kevin Henseler
Dr. Kevin Henseler is an interventional radiologist with Midwest Radiology in St. Paul, Minnesota.
Dr. Aaron Fritts
Dr. Aaron Fritts is a Co-Founder of BackTable and a practicing interventional radiologist in Dallas, Texas.
Cite This Podcast
BackTable, LLC (Producer). (2023, May 12). Ep. 321 – New Innovations in Lower GI Bleed Embolization [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
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