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BackTable / VI / Article
Catheter Selection for Cannulating Branches of the Aorta
Rajat Mohanka • Mar 14, 2024 • 135 hits
Understanding the correct catheter to use in different clinical scenarios is an important skill for interventional radiologists to save fluoroscopy time, reduce radiation exposure, and minimize the risk of causing vessel damage. There are several standard base catheters, such as the Cobra, Sim, or Berenstein, used for support in origin arteries. Beacon Tipped catheters have tungsten-based tips for improved fluoroscopic visibility and possess high torquability, which is beneficial in larger patients. Hydrophilic catheters are superior in navigating through tight lesions and turns due to their lubricious nature.
Dr. Kumar Madassery and Dr. Shelly Bhanot, two interventional radiologists from Rush University, further explain the benefits of a Beacon Tip catheter, and the various catheters used in the thoracic and lumbar aorta branches. This article includes excerpts from the BackTable Podcast. You can listen to the full episode below.
The BackTable Brief
• Base catheters like Cobra, Sim, or Berenstein provide origin support for arteries.
• Hydrophilic catheters are generally used for more distal work and in tortuous segments.
• The Mikaelsson catheter is ideal for bronchial embolization due to its multiple curves providing stability.
• Use reverse curve catheters, like the Sim, or sheaths to create a straighter path in tortuous anatomy.
• The SOS catheter is preferred for celiac and SMA, due to its efficacy and safety.
• The Cobra catheter is effective for anchoring in the SMA, but poses risks of aortic damage and dissection.
• Different catheters like SOS or Mikaelsson may be more effective for accessing tricky branches in visceral interventions.
Table of Contents
(1) Beacon Tip Catheters vs Hydrophilic Catheters
(2) Catheter Selection in Bronchial & Thoracic Artery Embolization
(3) Catheter Selection for Lumbar & Mesenteric Arteries
Beacon Tip Catheters vs Hydrophilic Catheters
Beacon Tip catheters are highly visible under fluoroscopy and offer high torquability. Dr. Madassery contrasts this with hydrophilic catheters, which, while offering less structural support, excel in navigating tight lesions due to their lubricious nature. It is important to choose a catheter that can achieve the balance between visibility, support, and maneuverability, especially in challenging vascular environments.Combining sheaths with hydrophilic catheters offers triaxial support for intricate navigation.
[Dr. Aaron Fritts]
Before we get into the actual shapes and we're going to start at the aortic arch, Kumar, if you can just kind of explain for the younger audience, what is a Beacon Tip and why is it important when it comes to a catheter?
[Dr. Kumar Madassery]
…it was a very visible, really nicely torquable type of catheter that was a workhorse for a lot of us. It had, I think it was, a tungsten-based tip, and so you could see it very well on fluoroscopy and it had a little bit of lubricity to it, which is a term that we use obviously in catheters, and the ability to kind of visualize where you're going in to hook arteries very easily, especially in larger patients, which we see in our society. It was really beneficial…It's a great workhorse type of catheter that you can see, which is one of the hardest things in the middle of a complex case, patients coding, dying, and you can't see your catheter.
[Dr. Aaron Fritts]
Right, exactly. Then there's hydrophilic catheters, which tend not to be Beacon Tip, right? Just for the audience, we're going to talk about base catheters today. We're not going to be talking about micro catheters. That's a whole other discussion, but I do want to talk a little bit about when and why we would use a full-on hydrophilic catheter, not just the tip.
[Dr. Kumar Madassery]
I think the great thing and to understand the concept, especially for the younger trainees, people may be listening, is that the base catheter gives you that support. When I use a Cobra or a Sim or a Berenstein, those are to get you support into the origin of whatever artery you're doing. However, sometimes even from a base catheter standpoint, you want to get a little bit further to get a little more distal, especially when you're doing micro catheter work or if you're doing a PAD and you're trying to cross tight lesions, the hydrophilic catheters are very lubricious and very slick.
They tend to pass very easily and a lot better than the non-hydrophilic catheters through tight areas, through turns, and through areas where you can do that a little more safely. Now, the downside of that is you don't have a ton of support with that catheter when you're advancing things. So when you're advancing through, let's say, a 4 French Glidecath or a 5 French Glidecath, you're pushing a vascular plug or you're passing something else through it, even a stiff wire, those catheters will buckle back because they don't have the support, but a Beacon Tip catheter and the other braided strong catheters, they'll hold their own. That's the caveat.
You'll get a lot further through tough lesions with the hydrophilic. However, you won't have the same support if you're in a very tortuous segment as the other base catheters.
[Dr. Aaron Fritts]
Are you tending to use a longer sheath if you know you're going to use the hydrophilic catheter?
[Dr. Kumar Madassery]
Yeah. A lot of the interventional oncology cases, when you're doing a liver directed therapy and you want to get your micro catheter, you know, 200 centimeters into the weeds, a lot of those times I'll take a sheath into the origin of the visceral and then a 4 French Glide hydrophilic catheter further into the main visceral artery and then to my catheter. That way, when you're making these 10, 20 turns, you have triaxial support in a sense. I think that's where the beauty of combining all these, and understanding which catheters where, when, and how comes in.
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Catheter Selection in Bronchial & Thoracic Artery Embolization
The numerous branches off of the thoracic aorta make it challenging to navigate bronchial and thoracic artery embolization cases. that Dr. Bhanot emphasizes the efficacy of the Mikaelsson and SOS catheters, noting their specific curvatures that facilitate stability and access in bronchial embolization. Dr. Madassery further elaborates on the challenge posed by tortuous aorta-iliac systems, suggesting the use of sheaths or reverse curve catheters like Sim for a straighter path. The discussion underscores the critical need for adaptability in catheter selection based on individual patient anatomy, as well as the importance of visual cues in catheter positioning, emphasizing the role of a 2D visual perspective in a 3D structure.
[Dr. Aaron Fritts]
Let's talk a little bit about the thoracic aorta. Also a place where we may need reverse curve, especially for bronchioles, bronchial artery embolization, and even in the case of thoracics where you might have a spinal lesion that needs to be embolized. Shelly, can you talk us through bronchial artery embolization, how you're getting that base catheter, select those?
[Dr. Shelly Bhanot]
Yeah, actually Dr. Madassery and I had one together not that long ago and he was like, "You have 30 minutes. Let's see what works". It's actually a really–
[Dr. Aaron Fritts]
Patient was stable.
[Dr. Shelly Bhanot]
Oh, yeah, patient was stable. That was extremely valuable because that was exactly as Dr. Madassery was saying earlier, a really great time for me to figure out why some of our basic go-to catheters are our go-to catheters. So first, I had the SOS. We tried the SOS is a nice reverse curve, and it's the double curve that helps you-- It can find the bronchioles in some situations for some patients. But in this patient, it wasn't as easy. The SOS wasn't finding the branches that I needed, so I ended up switching over for a Mikaelsson. The Mikaelsson is one of the classic catheters when it comes to looking for bronchioles. It has multiple curves that gives you nice stability when you do eventually hook into a bronchiole. Those are my go-tos to begin with.
[Dr. Aaron Fritts]
That's a great tip. Mikaelssons are hard to find on the cabinets in a lot of these community hospitals, so I've always been stuck with Cobra. Try first with a Cobra, but a lot of times Cobra, just given the angle of those bronchioles and then the width of the thoracic aorta, it's a little bit different from the abdominal aorta, it just can be challenging with a Cobra. Then I try something like a SOS and usually have success with that. I think the Mikaelsson's actually a great suggestion. I just wish it was more readily available.
[Dr. Kumar Madassery]
Yeah it's nice because that has a tapered tip. If you are able to get into it, it's not like you have the non-tapered, larger hole going into your small bronchial arteries or lumbars, whatever you're doing. The issue I see with some of those that we have difficulty is when you have a tortuous aorta iliac system because what happens is when you get your axis and you're going up, you're fighting the curves that your pathway has. If your catheter is going through a very tortuous iliac artery into an aorta now, that catheter is going to favor one side of the aortic wall and it may never hook the way you want to the side you're going. You know, in those situations, maybe something with a larger reverse curve, a Sim, or even if you put a sheath in the iliac artery all the way up to aorta, that provides a straight path for then your catheters to do a lot better. Those are things you'll combat, but a Mikaelsson or even a SOS, I think. Cobra as well, but the Cobra has the same problem if there's a lot of tortuosity. I think those are three that typically we would use for those type of areas.
[Dr. Aaron Fritts]
That's actually a great point, Kumar, is to keep an eye on what the iliac anatomy looks like because you're right, that's going to push you one way or the other. I don't think I realized that until I was later in practice and I'm scratching my head, like, "Why am I not able to get into this?" It's because you're just being pushed due to that tortuous anatomy. So I guess it would be the same for the thoracics, right? I mean, it's not often I have to access the thoracics, but it comes off in a similar angle as the bronchioles, but would you just go with the same thing for a thoracic?
[Dr. Kumar Madassery]
I think the thing is a lot of the times, it's a little bit of just twist, pull, advance, pull, see what you hook. It's a nuance to understand that what you're looking for is that catheter tip to suddenly deflect. That's your sign that you're into something because you can't really do roadmaps in the thoracic aorta looking for bronchioles or thoracic. I mean, it's almost impossible just because all the motion that's there, but you just watch it for the nuance of the catheter.
As trainees, remember that you're looking at a 2D visual picture, not a 3D. It's important to remember that you could be on the wrong side of the artery. It's a very important to think about that nuance, Aaron, you remember, and I'm sure, Shelly, how do you know you're anterior? You can probably remember your attendee saying, "You're not anterior." How do you know you're anterior? It's like–
[Dr. Aaron Fritts]
Yeah, and you just got to turn and see which way you're turning. It's a clock, you know?
[Dr. Kumar Madassery]
Yeah, you just gotta remember if you're standing on the bottom of the patient or the top of the patient, and when you turn the catheter one way outside, which way should it turn on your screen? Remember, just like radiology, it's the opposite, so you have to think about that every time.
Catheter Selection for Lumbar & Mesenteric Arteries
The SOS catheter is the primary choice for accessing the abdominal aorta at Rush, particularly for celiac and superior mesenteric arteries (SMA), though alternatives like the Cobra are considered if the SOS falls short. Dr. Madassery emphasizes the reliability of the Cobra in anchoring the SMA but cautions about its potential to cause damage due to its design. He also highlights the SOS and Mikaelsson catheters for accessing early branching vessels like the left gastric or inferior phrenics.
[Dr. Aaron Fritts]
Let's get down into the lumbar aorta. Selecting lumbars, honestly, when I'm looking for those mesenterics, commonly we'll be selecting lumbars because I'm on the wrong side but of course, when you're trying to select the lumbars, then you're selecting the mesenteric.
[Dr. Aaron Fritts]
I don't know. My go-to in the lumbar aorta is a C2 from the get-go. Let's start with the mesenteric because that's probably the most common thing we're trying to select for GI bleed or something like that. What's your go-to for celiac, SMA, IMA? Shelly, I'll start with you.
[Dr. Shelly Bhanot]
That's interesting that you mentioned that the C2 is your go-to. I wonder if this is just dependent on culture of your institution. At Rush, we always start with the SOS. The SOS is like our power finder when it comes to abdominal aorta, when we're looking for celiac, SMA. IMA, it's not always as easy to use the SOS and we end up switching out for other things, but if you're having any trouble with the SOS or you feel like that reverse curve is working against you and not giving you the stability you need, then the Cobra is usually the next step for us.
[Dr. Kumar Madassery]
Tell you, there's a reason why certain places may have reasonings because when you give a lot of latitude to trainees, you find out what all damage you can cause with certain things in the past. Historically, the Cobra, which is like that nice arching double curve almost, it's a great catheter and especially in the superior mesenteric, it really helps you anchor in there because the SMA is one that quite often when you do a SOS and you do a power injection, it pops out. The Cobra helps you, but the one thing that you have to understand about Cobra is you can damage the aorta and the osteoma vessels very easily if you're not careful.
With the SOS, people tend to push, pull, just re-anchor. With the Cobra, the way it's angled, you're going to potentially scrape plaque off, you're going to perforate, you're going to dissect. So for safety sake, since we care about patients primarily first, as we all should, certain people will be more heavy on certain ones and then switch to it when you're having trouble because the greatness of certain devices also come with a cost if you're not careful, so I think that's why.
But I agree with the Cobra being a fantastic catheter for the renals, for the main vessels that we do probably day to day. It's just the SOS has a little bit more safety and works just fine. Also the SOS, or sometimes I use a Mikaelsson if I have to get into the left gastric or the inferior phrenics because the left gastrics and the inferior phrenics comes really early off the aorta or off the celiac, and the Cobra will never get you into those. When you're doing visceral interventions, interventional oncology or bleeders, you often have to get into a left gastric and the Cobra will never get you into that.
In those situations, the SOS, once you engage the celiac and you pull down, a lot of times it angles right into the gastric. Same thing, a Mikaelsson, you pull down on the celiac, you keep pulling gently as you're injecting, and sometimes it'll just straighten out or flip in there. You have to think about what you're trying to accomplish, what you're trying to get to, what's going to give you the most success in those.
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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