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BackTable / VI / Article
Catheter Options & Advanced Cannulation Techniques in Challenging IR Cases
Rajat Mohanka • Updated Sep 19, 2024 • 998 hits
Having a fundamental understanding of which catheter options to select for more challenging interventional radiology cases can streamline procedure time and minimize risk of vessel damage. There are a number of catheter options that demonstrate their utility in very specific situations, such as the RBT catheter (previously the Roberts Uterine Catheter) in uterine fibroid embolization cases where the operator needs to cannulate arteries ipsilateral to the access site. Additional examples include the RIM catheter, which was made specifically for cannulating the inferior mesenteric artery, and the Multi-Purpose Angiographic (MPA) catheter, which is used for accessing hepatic veins during a Transjugular Intrahepatic Portosystemic Shunt (TIPS) procedure.
Dr. Kumar Madassery and Dr. Shelly Bhanot, two interventional radiologists from Rush University, explain the various catheters that they use in specific end-organ arteries, including the renal, uterine, gastric, mesenteric, and more. This article includes excerpts from the BackTable Podcast. You can listen to the full episode below.
The BackTable Brief
• The Cobra catheter, especially C2, is commonly used for its angle compatibility with renal arteries.
• The Renal Double Curve (RDC) catheter and the Sim catheter are alternatives for acute renal angles.
• Roberts Uterine Catheter (RUC), renamed as RBT, is favored for its efficiency in ipsilateral UFE.
• The RIM catheter is specifically designed for the IMA, with its short, tight curve.
• It is recommended to use the Cobra catheters or SOS catheters for right adrenal vein access, with possible modification by adding extra side holes.
• The MPA catheter’s primary use is for hepatic vein access during a TIPS procedure.
Table of Contents
(1) Catheter Options & Manipulation for Effective Renal Artery Cannulation
(2) Innovative Approaches in Catheter Selection & Navigation for UFE
(3) Strategies for Effective Catheterization of the IMA & Gastric Arteries
(4) Advanced Catheterization Techniques for Difficult Lower Limb Arteries
(5) Mastering Challenging Venous Access: Tips for TIPS & Right Adrenal Vein Sampling
Catheter Options & Manipulation for Effective Renal Artery Cannulation
The Cobra catheter, particularly the C2 variant, is frequently preferred to cannulate the renal artery due to its optimal angle alignment with the renal artery's typical 90-degree orientation. However, in cases of acute renal angles or other specific anatomical challenges, alternatives like the Renal Double Curve (RDC) cather or Sim catheter may be more effective.
A critical aspect of successful cannulation, as highlighted by the experts, involves cautious advancement of the catheter, especially in arteries with heavy plaque buildup or downward-facing orientations. This requires constant vigilance and techniques such as using a wire guide, contrast puffs, or saline to ensure safe navigation and avoid arterial wall damage. Additionally, for challenging aneurysmal or tortuous aortas, the use of tip-deflecting sheaths and improvisation with catheters like the RIM cather can be invaluable.
[Dr. Aaron Fritts]
…Renals, what are you using when you're trying to get into a renal to stop a bleed, for example?
[Dr. Kumar Madassery]
Yeah. Pretty much for the renals, normally it's going to be a Cobra, for the most part. There is the RDC, which is a renal double curve, which some people may choose just because it was designed for that when you have a really acute renal angle, then the renal double curve catheter are going to help but a Cobra, for the most part, the hard thing about renals and with the Berenstein sometimes is the Berenstein doesn't have that long of an angle tip.
When you're in the aorta, it's not going to give you an ability sometimes to get over to that side of the artery. If it goes in with a Berni, then that's fantastic, or Berenstein. Otherwise, quite often it's going to be a Cobra. Sometimes a Sim, if for some reason some people have a hard time, but I think with the RDC and other ones, you can really get that angle to get that downward angle hooked or other approaches.
[Dr. Aaron Fritts]
Yeah, because like the renal is going to be-- I mean, unlike, for example, SMA, which is going to be much more of an acute angle, renal is going to be 90 for the most part, roughly, and so, yeah, I think that's where I actually have probably the most luck with the Cobra, getting it right away is just because that angle's right. It's almost right on with the Cobra. Just to back up, the difference between the C1 and the C2, which are the two most common Cobras that are out there, it's a slightly different angle. I mean, that's the same thing with like all these variations. You know, there's SOS 1, 2, 3. In the case of the SOS, it's size-wise. The 1's a little bit shorter than the 2 and the 3. With the Cobra, the difference between the 1, 2, and the 3 is they're just slightly different angles but all have that Cobra shape, like the snake, that's why they're named that way. But yeah, for whatever reason, the most common one that I see in my private practice hospitals is the C2. It might be cost or it might be bundling or whatnot. But yeah for the renals, I totally agree. Then if it's some funny angle, then I go with the reverse curve, but yeah, C2 tend to be my go-to and I'm pretty successful with it.
[Dr. Kumar Madassery]
The thing with that, you got to be careful and for the ones who are getting nuances when you push that C2 into it, remember it's curved down. If you're not too careful, this is what I was talking about with the viscerals, you're going to be scraping the bottom aspect of that artery. You don't want to really be pushing it too far into it because anytime you're pushing a Cobra, you should be either using a wire or puffing contrast or saline to make sure it's bouncing off the wall. Otherwise, if you have heavy plaque, disease, whatever, it's scraping along it.
[Dr. Aaron Fritts]
It's probably the best place to use a Glidcath too, right? I mean, just because a lot of times you do have a lot of atherosclerotic plaque at that origin, get a Glidecath in there so that you're not worried about causing a dissection or screwing it up. Like you suggested earlier, that'd be a case where you'd use a longer sheath too, especially if you're placing a stent. We get these huge RCCs that they want us to embolize and you know you're going to be in there for a while, you just get a nice long sheath up there, get stable access.
[Dr. Kumar Madassery]
That's a great tip, and also the tip deflecting sheaths often will be needed in some of these cases where it can help you get closer off that artery origin when you have a big tortuous aorta. I'm having that as a backbone to redirect you.
[Dr. Aaron Fritts]
That's the other key thing is a lot of times these patients, they've got big aneurysms too, so what are you going to do with that kind of anatomy? Other than the C2, there is an actual renal selective catheter…
[Dr. Shelly Bhanot]
Aaron, you mentioned that you use reverse curve if the Cobra is a hard time. I know I've had my SOS hook into renals before. Is that what your go-to is or–
[Dr. Aaron Fritts]
Yeah. Yeah, it would be a SOS. Yeah, for sure. One thing I've done before is you take a catheter and you improvise, right? You take something like a RIM and you cut it right at the halfway part or just enough where it's more than like a Berenstein and you can sometimes get that to hook, especially when it's a downward-facing renal, and get that to hook in there. That's just when I just can't-- I start doing that after my third or fourth catheter. I'm just like, "Let me just try to make something on my own that seems to fit this shape."
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Innovative Approaches in Catheter Selection & Navigation for UFE
The Waltman's loop, traditionally used for forming a reverse curve in the aorta to facilitate access to the iliacs, highlights the adaptability required in many interventional radiology procedures, such as UFE, when using common femoral artery access. The conversation also brings forward the RUC (now known as RBT), which Dr. Madassery describes as highly effective for ipsilateral UFE procedures due to its design that facilitates easy selection of the uterine arteries. This catheter's unique hinge point and reverse curve enable efficient navigation from a single groin access point, significantly speeding up the process compared to other methods. Additionally, the use of an Omni flush catheter for bilateral uterine artery embolization, as mentioned by Dr. Madassery, demonstrates the versatility and resourcefulness required in these procedures.
[Dr. Aaron Fritts]
…we already talked about forming a Sims, but can you talk about a Waltman's loop just real quick and how you would use that to select and navigate a tortuous iliac?
[Dr. Shelly Bhanot]
…Is it like a Berenstein catheter or something that is more of a simple curve? Then you're able to create a reverse curve up into the aorta by pushing it upwards. Then it can help you select a left gastric, I think, is my impression of it.
[Dr. Kumar Madassery]
Yeah. A lot of people use it with a suture to try to help you do ipsilateral procedures when you have one catheter going up from one groin up and over. You'd sometimes get it up there. You'd pull on the suture to help it bring it down. People have done iterations where they take and push, but I mean, most people would use it for the iliac arteries selecting and coming back…we tend to use just the RUC, which became the RBT now when it came back. The Roberts…the one we use for uterine fibroid embolization. It's that catheter that took away the need for any really need to do a Waltman loop type of procedure because from a single groin access, we can treat up and over. We push the catheter up, turn it, come down. It's the quickest way I've ever seen in my hands to do a femoral artery approach uterine embolization. Literally, the catheter itself tends to hook the uterines for you.
[Dr. Aaron Fritts]
Yeah, I mean, that's how we did our UFEs is we formed a Waltman's loop. Typically, I think it was even just a C2. We'd put it over the aortic bifurcation. Then you take your wire, you get it down there past the branch into the external iliac. Then you take the back end of a wire, any wire, and you put it up towards the arch. You basically push the arc of the catheter up into the aorta. Then you turn it so that the tip of the catheter is actually pointed towards your ipsilateral iliac, common iliac. Then you bring everything down and then you just twist it and it automatically almost selects that internal iliac.
Then we'd put our microcatheter through and then do your ipsilateral UFE. Yeah, that was how I learned to do UFEs, and so I guess I didn't realize there was a new–
[Dr. Shelly Bhanot]
Oh, yeah. The Roberts Uterine Catheter, which is the RUC, is amazing…Like Dr. Madassery was saying, it's like a magnet for the internal iliacs, which it sounds like the Waltman's loop is as well. When I had looked up the Waltman's loop, I did see the literature saying, use that technique for the left gastric. Is that something you've seen?
[Dr. Aaron Fritts]
You can do that too because it's just changing the angle of the catheter tip. Like Kumar was saying, selecting that left gastric is all about the angle of the tip going up into that left gastric, and so you could push that whole
Waltman's loop up into the aorta and then select it that way, so yeah, you're right.
[Dr. Kumar Madassery]
You basically created a sense of like a Sim or a Mickelson with that catheter, so you're just using any catheter and making it a big double, like a reverse curve…I do have some older partners who will use just an Omni and I know it's crazy, but they'll just an Omni flush to do both internal iliacs. It does work and I've done it back in the days when some things went off-market or was back-ordered. You can still even use an Omni for bilateral uterine artery embolization. You can do anything with these as long as you know how to use these things…
[Dr. Kumar Madassery]
For those that don't know the RUC or the RBT, basically all you need is to get an up-and-over wire into the contralateral iliac, external iliac, or common femoral, and then you advance this catheter. The way Anne Roberts created it, there's a hinge point at the top of this huge long reverse curve so that when you get that hinge point over the aortic bifurcation, now you can go into the internal on that contralateral side, do your anterior division and the uterine.
Then as you push the catheter up, now it's going up in the aorta and the catheter tip is going to go up, up, up. Then you come and just twist and come down the ipsilateral side. If you just puff contrast, usually you can select the internal iliac, the anterior division, and quite often right into the uterine. So to me, it's like how people say a transradial UFE is so fast. I mean, with an RBT in the groin, it's faster or equally fast.
Strategies for Effective Catheterization of the IMA & Gastric Arteries
Catheterizing challenging vessels like the left gastric artery and the inferior mesenteric artery (IMA), particularly in cases of gastrointestinal bleeding, demands a nuanced understanding of catheter selection and manipulation techniques. A key insight from Dr. Bhanot involves the use of the RIM catheter, specifically designed for the IMA catheter, with its short, tight curve aiding in navigating near the aortic iliac bifurcation. Dr. Madassery further elaborates on the effectiveness of the RIM catheter, owing to its design tailored for the IMA, and suggests using an SOS catheter as an initial approach, leveraging its ability to torque and angle into the IMA. He emphasizes the value of oblique imaging during a DSA run to better visualize the vessel's origin, especially in stenosed or diseased conditions. Additionally, in more challenging scenarios, employing a glide wire or a microcatheter through the base catheter may be necessary.
[Dr. Aaron Fritts]
…left gastric and IMA can be tough to cath if there are stenoses. Any shape that can help? You know, the IMA, I kind of glossed over it when we talked about the mesenterics, but I think it's the most challenging vessel to catheterize, so if you guys have any tips for IMA, for like a GI bleed.
[Dr. Shelly Bhanot]
I mean, one that I've seen a couple of times it's worked for me is the RIM catheter, that nice curve can help back you into that origin.
[Dr. Kumar Madassery]
Yeah. The I and the M in the word RIM is for inferior mesenteric. The reason why that catheter has that name is because it was designed to help you with that. So some people use it. Actually, I know other specialists sometimes use that catheter for up and over aortic iliac alone, but that catheter has that nice, short, tight curve on it that when you're coming down that, that IMA comes just above the aortic iliac bifurcation. If you oblique your image when you do a run, you'll quite often see the origin if it's not heavily diseased or stenosis.
As you're coming down with that RIM, you're able to hook it. I'll usually start first with just a SOS. Quite often you'd be surprised if you just torque and angle as you come down, you'll be able to catch it. If that doesn't work, then I'll try something else. I would say if you're having trouble, truly, you can do a good DSA run in an oblique, a little bit off-center, and you might often find it, but between the SOS and the RIM, it's usually very feasible.
Now, sometimes it might be so tight that you got to get a glide wire or even a micro catheter through your base catheter to try to get in there, but those are step one, two, three for me on those, but they are challenging, and make sure it's actually there.
[Dr. Aaron Fritts]
Make sure it's there and make sure it's not occluded. If they had a CTA, take a look at the CTA, and you don't even need to mess around with the IMA if there's no bleed there.
Advanced Catheterization Techniques for Difficult Lower Limb Arteries
In the context of accessing challenging lower limb arteries, particularly in cases involving tortuous bifurcations, clinicians must employ a range of advanced techniques and catheter options. A common approach includes starting with an Omni flush catheter, utilizing a Bentson catheter or Glidewire catheter to navigate the initial pathway. In more complex scenarios, alternatives like the RIM catheter or crossing catheters are considered, especially to advance the wire distally for greater stability.
Dr. Madassery emphasizes the importance of understanding the underlying challenge, whether it's a steep or tortuous bifurcation, and adapting the strategy accordingly. This might involve switching to straighter, more hydrophilic catheters, or even tip-deflecting sheaths for better anchoring and wire support. In extremely difficult cases, a contralateral approach with a bareback snare to create a flossing access can be effective. Additionally, he highlights the critical technique of sheath advancement over a wire, advising to ride the sheath over the dilator at the aortic arch to prevent misdirection.
[Dr. Aaron Fritts]
He wants to know, what about tough up and over access for legs, like a really torturous bifurcation? Any tips for that?
[Dr. Shelly Bhanot]
Honestly, I feel like a majority of our cases doing an Omni flush, getting up and over with the Bentson or Glidewire through the Omni helps a lot. For the really difficult ones, I mean, very rarely I've seen you pull out the RIM catheter to get us up and over. Or sometimes if you're able to get a wire just a little bit over that arch and if you're having a hard time advancing the wire, getting more distally, then you switch to a crossing catheter to help you advance that wire to get more stable.
[Dr. Kumar Madassery]
Yeah, I think it depends on what you think is the reason why you're having trouble. If it's because of a steeped bifurcation versus a tortuous, heavily diseased bifurcation, that's going to be, I think, my mindset. I usually always start with an Omni. If I can get a wire down all the way up and over into the common femoral or SFA on the other side, and if the Omni is not going, then I switch to a straighter catheter, either a straight flush or a Glidecath, or sometimes like Shelly said, a crossing, like a recanalization support catheter because those are all smaller and smaller.
If it's for a really difficult case, then you can try a tip-deflecting sheath up and over to help you anchor, to get your wire support all the way down because sometimes all you can get up and over is a glide wire, which is not supportive for much of anything, so you might need something else. If it's super difficult and nothing's really working, what I'll do in those situations, I'll stick the contralateral common femoral artery retrograde. I'll keep a small 018 access. I'll get that wire up and I'll put a bareback snare. I'll grab the wire from the aorta. I'll bring it down.
Now I have a flossing access to then advance my catheter and sheath up and over. Then all I had was an 0.018 hole, like a micropuncture hole. I've done that a few times where nothing else is working and it's not a case where I can just go anti-grade down the leg. Otherwise, I'd prefer to do that anyway. Those are kind of my steps, is either get a smaller catheter, a more hydrophilic catheter to go up and over if I have good wire access, even a glide wire.
If not, switch to a support catheter and then put a stiffer wire through a support catheter because once you get a stiff Amplatz, super stiff, whatever, Lundquist, then usually anything will go over it as long as you practice riding the sheath over the dilator right before you get to the arch. That's the one thing that people still mess up. They'll get a wire, even a stiff wire, and they're advancing their sheath, and all of a sudden now, their wire goes up in the aorta. Usually, it's because that dilator is stiff and it's tapered down, so as you're pushing, it becomes a little bit of a spear, so it's going to push your wire at the bifurcation straight up.
When you get to that aortic arch, you just peel off the sheath from the dilator, let that go over. Once you get the sheath over, then you put the dilator back all the way. Those little things will help those difficult things, and Sabeen needs a lot of help in most of his cases.
Mastering Challenging Venous Access: Tips for TIPS & Right Adrenal Vein Sampling
When performing TIPS procedures and adrenal vein sampling, clinicians often encounter unique challenges that demand innovative catheterization strategies. The MPA catheter is frequently the first choice for accessing the hepatic vein in TIPS due to its versatility, with the Cobra or C2 catheter as alternatives when the MPA catheter is insufficient. However, the doctors caution about the risk of entering the right atrium with these catheters. An unconventional but effective technique mentioned is using a Launcher coronary catheter, which, due to its unique shape, can facilitate access to the right hepatic vein when other catheters fail.
For adrenal vein sampling, especially the challenging right adrenal, clinicians often start with a Cobra catheter or an SOS catheter, sometimes adding extra side holes for better aspirate flow. A novel technique shared by one of Dr. Madassery’s colleague involves using a micro wire and catheter to offset the main catheter from the IVC wall, enhancing lumen access.
[Dr. Aaron Fritts]
That's a great point. Okay speaking of venous cases, the last two I wanted to talk about before we finish up are access catheters for TIPS and then we talked a little bit about adrenal vein sampling but we can touch on the right adrenal because it's where I talked about left adrenal. But for TIPS, I usually use just the multi-purpose or a hockey stick but sometimes the angle's tricky, right? Shelly, what's your go-to for TIPS getting into that right hepatic?
[Dr. Shelly Bhanot]
Yeah for the hepatic vein similarly, the MPA is our go-to. I have pretty reasonable success with that.
[Dr. Kumar Madassery]
Yeah, we'll go MPA as a primary thing that we have open for every even transjugular liver biopsy because you have to get to the same vein for those things. My method is usually MPA and by the way, MPB is like an MPA but it has side holes at the tip of it, but MPA is all you need for those situations. But if the MPA doesn't go, and there's some nuances to remember how to get in there and most often people aren't high enough because you're seeing the heart and you're thinking, "Oh, wait. I'm too high," but really you're not there yet because the hepatic confluence is probably a little higher.
If that doesn't work, then I'll go to Cobra, a C2, but the problem with that is when you get high up near that confluence, you're going to pop into the right atrium easily. My last go-to ditch effort that I'm not sure if many people use is a Launcher. It's a coronary catheter, but what it is is basically imagine a SOS but upside down, so basically when you put this catheter down and you form it in the IVC, now it comes with a catheter-like-- so it's got like a question mark with a flat line. So what happens is when you come up now with that catheter and it's got this question mark, as it's coming up towards the heart, that horizontal tip will catch the right hepatic vein. So that's my last go-to.
The problem with that is you can't really advance it into the hepatic vein. If nothing's working, I'll use that to get a wire down and then switch out to another but honestly, that saved me a few times when nothing else was working.
[Dr. Shelly Bhanot]
I remember in the beginning of the year, I was doing a transjugular liver biopsy and having a tough time getting into the right hepatic. That was such a nice case because we tried everything. We tried the MPA. We tried the Cobra. Everything just kept buckling out. I remember when he asked for the Launcher everyone in the room was like, "What?" and the tech came back, took a few minutes to find it, but it actually nicely seated us into the right hepatic. Then we were able to complete the case shortly thereafter.
[Dr. Kumar Madassery]
You know, one thing important for trainees is when we talked about walking around and looking at supplies. Walk around to the other specialty supplies too. A lot of things that everybody's adopted from IR has come from understanding the shapes and the lengths and the uses that other people are using. I mean, we learn in transradial how to use Sarahs and Jackys for viscerals because of the coronary catheters. That's where they're from. If you just rely on what you have, you'll never be able to improvise in situations, which is what our specialty kind of is about, so understanding what all is out there and when you can use it I've learned different things.
I’ve used the Penumbra select long catheter for UFEs from the radial because it just made sense for me from a neuro standpoint. They use it for that. It's long and it's nice. You never know what you're going to use but understand the shapes, why, how, I think that's important.
[Dr. Aaron Fritts]
Well, you just made a great point Kumar. I realize, this whole discussion has been centered around femoral access. It's all about where you're coming from. If you're coming from radial or you're coming from IJ, it's going to be a completely different angle. I mean, we're just talking about TIPS we're talking about coming from the IJ, but last one that I want to talk about is the right adrenal, which is maybe next to if not equal to the IMA as one of the most frustrating vessels to catheterize. What do y'all go to for a right adrenal?
[Dr. Kumar Madassery]
I mean, you can use either a SOS with some extra side holes. You can use a Cobra, a SIM. The problem with the SIM sometimes I think with that is and again, I preferentially and luckily don't have to do a lot of these, but the problem with the SIM sometimes, it gets you too far deep into it because of how long that that front end is, so I think having something else like a SOS or a Cobra may have a better shot when you make extra side holes because you need to be able to get the aspirate through it with a check flow or whatever else you use in there.
It depends again how far you are off your IVC wall being able to hook that. I think personally the right adrenal is probably harder than any other vein.
[Dr. Aaron Fritts]
…from what I remember it was always try a Cobra first, then SOS. That the algorithm.
[Dr. Kumar Madassery]
One of our one of our IR friends in Canada, Bao, he always talks about he puts a micro wire, micro catheter to offset the catheter so it's not stuck against the wall. He keeps that in there as a little balancing act so that you're actually within the lumen and have a lot better access in there.
[Dr. Aaron Fritts]
Okay. He just aspirates through the micro catheter?
[Dr. Kumar Madassery]
I think Bao just stares at it and somehow it works. He's a magician, but he has usually a tuohy in the back, so he has dual access approaches there.
Podcast Contributors
Dr. Kumar Madassery
Dr. Kumar Madassery is a practicing interventional radiologist with Rush University in Chicago.
Dr. Shelly Bhanot
Dr. Shelly Bhanot is an integrated IR/DR resident at Rush University in Chicago, Illinois.
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, September 4). Ep. 362 – Catheter Shapes: Basic to Challenging Cases [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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