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BackTable / VI / Article
Renal Artery Embolization Procedure in Trauma
Sai Govindu • Jun 30, 2023 • 127 hits
Renal artery embolization for renal trauma can be done using various techniques with different access and embolization devices. There are many factors to consider when performing renal trauma embolization. Interventional radiologist Dr. Nima Kokabi shares his approach to renal artery embolization in renal trauma, detailing the benefits of radial access, the renal artery embolization devices that he prefers, and the specifics of his renal artery embolization procedure technique.
This article features excerpts from the BackTable Vascular & Interventional Podcast. We've provided the highlights here, and you can listen to the full episode below.
The BackTable Brief
• Dr. Kokabi recommends radial access for renal angiography in trauma cases. Despite an initial learning curve, radial access offers superior image quality, convenience in specific cases of pelvic trauma, and can also help to facilitate better post-procedure care.
• Dr. Kokabi also recommends utilizing specific catheters for precise angiography. Base catheters such as the Sarah and Jacky catheters are recommended for accessing the renal artery and for obtaining two projections of the kidney to determine the bleeding artery. Microcatheters like the TruSelect are also preferred for renal cases due to their size and ability to provide good image quality.
• Detachable coils for renal artery embolization, such as the Embold Coil, are often used due to their greater control during placement and compatibility with a variety of microcatheter sizes. Embold and Interlock fibered coils are also preferred for their quick embolization and detachment features, which are particularly useful in patients with hemorrhagic shock. In Dr. Kokabi’s experience, the nitinol-based pusher in Embold coils prevents bending and kinking during rapid deployment.
Table of Contents
(1) Radial Access for Renal Artery Embolization in Trauma
(2) Renal Artery Embolization Microcatheters & Embolization Devices
(3) Renal Artery Embolization Procedure: Coil Deployment & Imaging Frequency
Radial Access for Renal Artery Embolization in Trauma
Dr. Nima Kokabi recommends competency in radial access, especially in trauma cases. While there is an initial learning curve, the benefits of this method include improved quality of imaging, the versatility for different cases including pelvic trauma, and the improved post-procedure care. To maximize accuracy during angiography, base catheters like Sarah or Jacky can help secure at least two projections for the kidney to discern the bleeding artery. Subsequently, a microcatheter helps target the specific artery for embolization. Furthermore, being adept at both radial and femoral access can be beneficial to manage different trauma, underlining the need for comprehensive training for fellows.
[Chris Beck MD]
All right, say we have a patient either in BC with blunt trauma or iatrogenic - could be post partial nephrectomy. Now you have a patient that you do want to take to angio, can you talk about your procedure prep, access, what you do to get that patient ready to just have an angio and prep for a potential embo?
[Nima Kokabi MD]
Sure. I'm a big fan of radial access.
[Chris Beck MD]
All right, radial access man.
[Nima Kokabi MD]
I was actually not trained, apart from a couple of attendees that I had at Yale, almost everybody else was a groin access or femoral, as you want to call them. I didn't have much of a radial experience, again, apart from maybe 10 or 15 cases I did with a couple of surgeon attendings. By the time I got to Emory, Zach Bercu, who was one my partners at Emory, he trained at Sinai. Being trained at Sinai, obviously, you become a radiologist whether you like it or not. He basically really taught me different techniques for radial, and I can tell you, I used that.
There is a bit of a learning curve initially, especially when you are all used to standing on the right side of the patient, and I'm right-handed as well. It is not the easiest learning curve, but once you learn it and you're comfortable with it, I think the quality of the images from radial access because of the extra side hole that most of the radial catheters have for both liver, I do all my IO cases radial, if possible.
[Chris Beck MD]
Sure.
[Nima Kokabi MD]
For trauma as well, particularly for pelvic trauma, which we're not talking about today, but because they usually have binders, it’s much easier to go from the radial, in my opinion. That was another change that we made in the past two or three years at Grady to make sure that people are comfortable taking care of these patients afterwards.
Anyways, long roundabout answer to your question, but if I can, I do radial access for these patients. My go-to catheter for accessing the renal artery, the base catheter is Sarah or Jacky. They're actually really easy to use to select the renal artery and then you can get good angiography. Generally, you need at least two projections for the kidney to figure out what artery is bleeding and whether you have to go to the upper pole, middle pole or the lower pole of the kidney.
Once I have that information - and those angiographies are done with the base catheter, which is a 5 French catheter in the case of Sarah and Jackie, then I use a microcatheter to select the renal artery if there is a artery to be targeted for embolization. Generally, if you have significant bleeding you will get a pseudoaneurysm or you get an active extravasation.
[Chris Beck MD]
Hold on. Before you get into the microcatheter, one thing that I wanted to ask you is like going back to the radial access, radial versus femoral, but it seems like you feel pretty good moving between both worlds, right?
[Nima Kokabi MD]
Yes, for sure. Actually that's one of my concerns about some of our fellows at Emory because a lot of us we do radial. Luckily we had a good group of people from all over the country, so the newer attendings were actually femoral access people, so our fellows would learn both. The bottom line is you need to be comfortable with both, for sure.
[Chris Beck MD]
I totally agree. Going back to doing radial access in the setting of trauma, which we're not a trauma center at the place that I work, but we do see fair amount of iatrogenic injuries. I've stayed away from radial access and trauma, but it's not because I'm not comfortable with it, but I always thought like, "Oh, the vessels are going to be clamped down or I'm going to have a lot of trouble getting into the radial." Is that not the case whenever you have someone?
[Nima Kokabi MD]
Not unless they're in significant shock and even if they're in significant shock, a lot of times you can get it. People that have concerns about that. I always tell them if an anesthesiologist can do an art-line on a patient with shock, you are definitely more equipped than them to do it, so you can actually access the radial.
[Chris Beck MD]
Well said. You were starting out, and I also wanted to ask you a little bit about your angiography technique for the renals. All hand-injections with these?
[Nima Kokabi MD]
Yes. All hand-injection. Some people are concerned about atherosclerotic plaques, so they do no-touch technique, which I don't do, and I'm not very good at it. Luckily, I've had no issues with just selecting the artery and parking my base catheter in the proximal aspect of the renal.
[Chris Beck MD]
That was the other thing I was going to ask you, if you just fully engage. Then once you do engage, you take an AP and then with your other oblique, is it just based on which side of the kidney it's just in oblique?
[Nima Kokabi MD]
Usually, you do contralateral oblique to open up the kidney.
[Chris Beck MD]
It also takes it off the spine?
[Nima Kokabi MD]
Yes.
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Renal Artery Embolization Microcatheters & Embolization Devices
The choice of embolization materials for renal trauma, namely coils, is largely dictated by the unique clinical context and CT findings. Detachable coils are a common choice for their control and versatility, especially in smaller areas. The TruSelect microcatheter from Boston Scientific has become a preferred instrument, in part because it enables the use of coils from 2mm to 32mm, all while providing satisfactory imaging. Moreover, the Embold Coil by Boston Scientific has resolved the earlier incompatibility issue between smaller coils and larger microcatheters. Furthermore, the application of Gelfoam is highlighted, albeit sparingly, as an adjunct in renal artery embolization. In the context of renal procedures, there's a consistent effort to be as selective as possible in order to preserve the maximum kidney function. Nevertheless, Dr. Kokabi stresses balancing technical decisions with the clinical picture, emphasizing the need to preserve renal function while minimizing procedural risks.
[Chris Beck MD]
After you've done your runs through your base catheter, and you've identified either pseudoaneurysm, active extrav, sometimes you see like an AV fistula, next step is micro and what do you like for micro?
[Nima Kokabi MD]
Next step is micro.
[Chris Beck MD]
Then also like, are you picking your micro, do you have an idea of what you want to embolize with?
[Nima Kokabi MD]
Depending on the CT, generally you have a fair idea of what you want to embolize with. In the kidneys, I would say majority of the time, at least for me, it's coils. I generally do coils. If I'm treating AML, I do alcohol and lipiodol. Sometimes for larger Renal Cell Carcinomas that I'm planning to do an ablation, I do a pre-ablation embolization to get better margins and reduce bleeding. My go-to ablation is cryoablation. For larger tumors, there could be a risk of bleeding, but if I'm doing that, I use particles. For trauma purposes, generally I use coils. I have partners that use glue as well, but I feel more comfortable with coils.
[Chris Beck MD]
As far as coils, glue, Gelfoam, have some of the Gelfoam on the table?
[Nima Kokabi MD]
Gelform, rarely in the kidney, a lot in the liver. That's my go-to in the liver, unless I see blood pouring out of the liver, I feel comfortable gel-forming the whole liver, if I have to, but also pelvic trauma, for sure, that's my go-to. For spleen and kidney, rarely. Rarely.
[Chris Beck MD]
All right. Coils are the workhorse.
[Nima Kokabi MD]
Yes.
[Chris Beck MD]
You've got the base catheter done, you have an idea what you're going to embolize with. What do you like for micro and how do you get distal?
[Nima Kokabi MD]
Generally for kidney, the vessels are generally smaller than the liver or spleen, so you want a smaller microcatheter. Anything from 2.0 to 2.4 is what you should aim for because you have to think about, depending on the type of coil you use, you're going to be using smaller coils in general. I would say in the past three years or so, when the TruSelect microcatheter came out by Boston Scientific, that has become my go-to microcatheter for all my IO cases, as well as my embolizations. I love it. Generally, kidneys are not super tortuous, like the liver, especially the IO cases that have been treated in the past, they become very tortuous, especially if they're on chemotherapy.
Even in kidney, I like the TruSelect a lot and you get good images, even if you're doing a selective angiography, because although the tip of the microcatheter is a 2.0 French, the distal aspect of it is a 2.8 French. It gives you that extra volume for your contrast injection.
[Chris Beck MD]
All right. Still getting pretty good pictures. Having the smaller microcatheter, does it limit you on which coils you like, or you're fan of detachable versus pushable?
[Nima Kokabi MD]
I'm a big detachable person.
[Chris Beck MD]
I’m quite detachable coils also.
[Nima Kokabi MD]
Yes, and I feel most of the younger IRs are detachable users, and most of the older IRs are pushable. They probably called us a bunch of wusses, who are using all these detachable coils, but I feel comfortable. Especially in smaller areas, I'd like to have that control, that if I don't like the place then I can retrieve it. I use detachable almost all the time.
[Chris Beck MD]
Okay.
[Nima Kokabi MD]
With some of the newer coils that are on the market, that whole issue of knowing what size coil you need to use to match that with a certain microcatheter has been resolved, particularly the coil that I like. That's another issue that we've dealt with in the past with many of the coils that if you're going for smaller coils, for example, you cannot use a 2.7 or a 2.8 French microcatheter because the coil actually forms in the microcatheter itself. The Embold Coil by Boston Scientific, that came out about a year and a half ago or a year ago now, actually is compatible for every microcatheter with an inner diameter from 2.1, I believe to 2.7. Even though the 2.0 French microcatheter, the TruSelect that I use, the inner diameter is 2.1, it's been okay. I've used anything from a 2 millimeter coil with a TruSelect all the way to the 32 millimeter coil.
[Chris Beck MD]
Really?
[Nima Kokabi MD]
Yes.
[Chris Beck MD]
What were you doing with those 32 millimeter?
[Nima Kokabi MD]
32 was a pseudoaneurysm that was coming in a patient with FMD that was coming off the pancreaticoduodenal arcade.
[Chris Beck MD]
Wow, okay. All right, going back though to a renal case, you like the TruSelect microcatheter, very nice, very slick, then Embolds are your coil of choice, detachable coils. If you see pseudoaneurysm versus extrav, how you approach those? Is it really any different, or you just group all those into vascular injury, treat it all the same, where you're just doing a vessel takedown?
[Nima Kokabi MD]
I generally do that. Sometimes I maybe do a touch of Gelfoam before I do the coil, but generally in the kidney, coil is enough because you don't have to worry about collateral vessels. In the GDA area, if I'm using coil, which is again my go-to, you do the back door, I sometimes do some Gelfoam in the middle and then do the front door, but generally, in the kidney, coil has been good enough for me.
[Chris Beck MD]
I like it. How subselective do you get? I know it sounds basic, but for the younger audience, do you get as absolute distal as possible? You try and leave as much kidney on the table?
[Nima Kokabi MD]
Exactly. You want to keep as much of the kidney, but again, you have to have the context of the clinical picture of the patient in mind as well. I had an attending at Yale who would tell us, life over kidneys anytime. They asked us, "Oh, but the patient has renal failure, can we give contrast, blah, blah, blah?" You have to put that in context, that if the patient is crashing on the table, you may not be able to be as selective as possible, but obviously, try to save as much of the kidney as you can.
Renal Artery Embolization Procedure: Coil Deployment & Imaging Frequency
Post-embolization injection can be done through both the microcatheter and the base catheter to ensure no leftover areas need embolizing. Fibered coils offer quicker embolization, which is especially beneficial in situations of hemodynamic instability and hemorrhagic shock. The Embold coil's nitinol pusher allows for rapid and efficient coil deployment without fear of bending or kinking, further enhancing the speed and precision of the procedure. Their rapid clotting ability allows for quicker confirmation of successful embolization and brings added advantages such as more robust pushability due to their nitinol base. This swiftness, however, doesn't replace the need for a brief wait time between embolization and post-runs, typically one to two minutes for fibered coils and four to five minutes for purely metal ones. In cases with nephrostomy tubes and undetected bleeding, using radial access allows for efficient angiograms and the possibility of tube removal.
[Chris Beck MD]
After you do your coils, you get your coils deployed, post-injection, do you do one through the microcatheter in the base catheter?
[Nima Kokabi MD]
Yes, I do both. I do one through the microcatheter because the idea with that is that if there's anything left to be done, you can continue with the coiling, and if everything is good, I'm also a big fan of doing another injection through the base catheter because sometimes you may be fooled with the microcatheter that yes, the flow through the vessel that you're embolizing has stopped, but then you do your injection through the base catheter and actually, it has not.
[Chris Beck MD]
Let me ask you this. How long do you wait from embolization to your post runs?
[Nima Kokabi MD]
It is a quick takedown. That's another thing I like about Embold because it is a fibered coil.
[Chris Beck MD]
Oh, they're fiber?
[Nima Kokabi MD]
Yes, they are. It's similar to the interlock, but I never liked using interlock because to me, it wasn't a really truly detachable coil. Once you had pushed it out of the microcatheter, you could never retrieve it, but people that use it, it's very popular, particularly among the vascular surgeons, the interlocks because A, it comes in a O35 platform as well, but the more important thing is the fact that it has fibers and a lot of times they use it for pre-EVAR. You end up using less coils. You don't have to get a perfect feeling of the vessel or the pseudoaneurysm that you get to get a cessation of flow.
Generally, the embolization is quicker, in terms of when you use any coil that has fibers on it, which both interlock and the Embold coil, which I use now for most of my embolization, actually has that. Particularly, that's important in the setting of a patient who has hemodynamic instability and hemorrhagic shock. You want to be as quick as possible. That's one of the advantages of it.
Then the other thing that I like about it is the fact that it actually is the only coil that I know of on the market that actually the pusher is nitinol. I'm very impatient. I don't know about you, Chris, when I'm pushing these coils in, I want to go as fast as possible. A lot of times I end up bending coils that are actually on a non-nitinol base. For the first time, there is a coil that I can push as fast as I can, and I can totally bend it even 180 degree and it doesn't actually kink. That's another advantage of the Embold coil that I like.
[Chris Beck MD]
How long do you wait after you embolize, it's almost immediate?
[Nima Kokabi MD]
With the fiber coils, I give it about a minute to two. With the purely metal coils, you need to probably do more coils because you want to get complete feeling, because you're solely relying on the metal to stop the blood flow. Generally with the metal, I would say about four to five minutes before I make a decision if I need another coil, whereas with the fibers, about two minutes.
[Chris Beck MD]
Sometimes that two minutes and that five minutes - that can be a long time.
[Nima Kokabi MD]
I know. Again, I'm not waiting between every coil, two or five minutes. When I feel visually that it is good enough for that vessel, then that's the time I would wait.
[Chris Beck MD]
Special considerations, is there any conversation around, or do you have any clinical scenarios where you have patients with nephrostomy tubes, and they're having hematuria, but you can't find the bleed with the drain in? It's similar to when you have it with same thing with biliary drains. Do you do anything different where you have them prone, and then you take out the drain, do an angio?
[Nima Kokabi MD]
That's actually another good thing for people that are radial fast.
[Chris Beck MD]
Exactly what I was thinking.
[Nima Kokabi MD]
That's another good application for doing an angiography through a radial access because unlike the liver, which is much easier, if you have a biliary drain and they have hemobilia to do an angiography with the patients supine, you can remove the catheter or wire, and then do another angiography. With kidneys, it becomes very difficult to do that. If you put them in a prone position, you can easily actually access the radial artery with the arm of the patient on their side, and then go into the kidney, do an angiogram with the nephrostomy tube in place, and then if you don't see anything removed in a nephrostomy tube over the wire, then repeat that angiogram. I think for people that are not a believer in radial access, that's another good application for it.
[Chris Beck MD]
I think that's actually super elegant solution. I've never had to do it, but I feel pretty comfortable with radial and I've always known that that's in my back pocket. I kind of feel similar to you, Nima, about radial access, that it's not appropriate for every case, but it's a good fit for some patients. If you're comfortable in both worlds, I think there's going to be a lot of clinical scenarios that you're going to be glad you have it in your back pocket.
[Nima Kokabi MD]
I think as a trainee particularly, and I know you have a lot of trainee fans who listen to you guys religiously, I think you should make every effort to become proficient at both techniques because a lot of times in very difficult situations, one may be a better option than the other. You would like to have both proficiencies in your back pocket, for sure.
Podcast Contributors
Dr. Nima Kokabi
Dr. Nima Kokabi is an interventional radiologist at Alberta Health in Calgary, Canada.
Dr. Christopher Beck
Dr. Chris Beck is a practicing interventional radiologist with Regional Radiology Group in New Orleans.
Cite This Podcast
BackTable, LLC (Producer). (2023, May 15). Ep. 322 – Renal Trauma 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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