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BackTable / VI / Article
Management of Clot in Transit: Challenges & Solutions
Caleb Solivio • Updated Jun 23, 2023 • 93 hits
Clot in transit is a serious diagnosis, as dislodgement can cause distal embolization resulting in end-organ ischemia and possibly death. Treatment of clot in transit often requires multi-specialty collaboration, patient-specific anatomy knowledge, and competency with imaging techniques, specific medical devices, and equipment. Even with these measures in place, complicating factors like shunts or concomitant pulmonary embolisms (PEs) can arise. In this article, Dr. Rehan Quadri looks back at some of his most challenging cases to explain how he navigates such challenges and successfully manages clot in transit. This article features excerpts from an episode of the BackTable Vascular & Interventional Podcast. You can also listen to the full podcast below.
The BackTable Brief
• Becoming familiar with instrumentation can be accomplished by consulting colleagues or company representatives. Operator-equipment competency also goes back to training, during which it is important to be exposed to numerous cases with different physicians because technique and preferred tools may differ between operators.
• Pre-procedural imaging using intracardiac echocardiography (ICE) or transesophageal echocardiography (TEE) is necessary to clarify clot size, confirm clot location, and guide catheter placement to prevent iatrogenic complications.
• During pre-procedural assessments, look out for interatrial shunts or patent foramen ovale (PFO). Failure to acknowledge these features can necessitate involvement of cardiothoracic surgery.
• Clot in transit should be treated before a concomitant PE unless the PE is massive, in which case the PE should be treated first.
Table of Contents
(1) Treating Clot in Transit: Lessons Learned from Dr. Quadri’s First Case
(2) Clot in Transit in Patients with Shunts
(3) Clot in Transit with Concurrent Pulmonary Embolisms
(4) Dr. Quadri’s Most Challenging Case
Treating Clot in Transit: Lessons Learned from Dr. Quadri’s First Case
Treating clot in transit, similar to other endovascular thrombectomies, is a collaborative effort that requires understanding of patient-specific anatomy and operator-equipment competency. Dr. Quadri cites his past experiences with Dr. Minhaj Khaja and Dr. Ziv Haskal at UVA and supportive colleagues as contributions to procedural success. It is important to use imaging modalities, such as intracardiac echocardiography (ICE) or transesophageal echocardiography (TEE), to establish a strong baseline understanding of how much clot is present before intervening, confirm clot location, and guide catheter placement to prevent potentially dislodging the clot and embolizing a distal structure.
[Dr. Michael Barraza]
…Let's talk about for a minute how you treat them. What are you usually using for treating these?
[Dr. Rehan Quadri]
It's interesting, the first time I was asked to do this was - we have a cardiothoracic surgeon who actually does cardiac transplants, his name's Dr. [Lynn] Huffman. He is extremely well-versed in AngioVac. There was a consult that was sent to both of us for a malfunctioning dialysis catheter and a clot in transit. He was like, "This guy's a dialysis patient." He's like, "Putting this guy on VV-ECMO is going to be a nightmare." He's like, "I'm not going to be able to get the cannulas in." He's like, "We can do it, but realistically, this is a borderline clot. It's stuck to a fibrin sheath. It's not a true clot in transit, but it's concerning." I just had a conversation.
I said, "Look, in training, when I was at UVA, I worked with Dr. Khaja and Dr. Haskal and all the attendings there did a ton of advanced thrombectomy work." I'm really lucky that they were able to teach me these skills and how to navigate these problems. I said, "Now, there's a 24 French Inari catheter." Before that, it was only 20. I said, "Technically, we can get - it's eight millimeters, but in reality, these clots are relatively spongy. Even though it's 2.8 on the echo, there's probably some magnification there." We got a CTA and it was ranging from 1.5 to 2.8. Then having done a lot of iliocaval thrombectomies with Haskal and Khaja, I was like, "We've taken out significant pieces of clot in one fail swoop."
I was like, "I think I can get this," but I would just need either transesophageal echo or I would need an ICE catheter, so I chose to go ICE. Huffman was like, "Look, I'll back you up. Anything happens, you let me know."
[Dr. Michael Barraza Barraza]
That's awesome. It's so great going into a case like that.
[Dr. Rehan Quadri]
Yes, I know. He's awesome and he's this huge dude and he's just so reassuring. He's got this really, really comforting vibe to him. When we were looking at the case, he was like, "No, don't worry about it. You'll be fine." He's like, "It'll come out."
…
[Dr. Rehan Quadri]
Yes, and the fact that the guy was in a real bind, and then ended up doing very well after the situation was good. Then also having great colleagues at the time. Actually, Joseph McLaughlin was there. He was one of our former faculty. He went to Wisconsin and I said, "What do you think?" He goes, "I don't know, but I'm in."
…
[Dr. Michael Barraza]
What'd you use?
[Dr. Rehan Quadri]
We went in with the 24 French Inari.
[Dr. Michael Barraza]
Did you use a FlowTriever?
[Dr. Rehan Quadri]
Yes, we used the FlowTriever. Then at that time, they had just come out with the FLEX. We didn't necessarily need the FLEX, but it was extremely helpful. In our heads, we're like potentially, it could accommodate more than what we thought and we could potentially angle if we need to by bending the wire, putting the wire in the PA, and getting the right trajectory. Then we decided to go with ICE. We have St. Jude, and then we also have AcuNav. I like the St. Jude catheter, but they're both, at the end of the day, the same functionality. The first thing we did was got a left groin access, had to partially recan[alize] the veins because they were pretty stenotic.
[Dr. Michael Barraza]
Why left instead of right?
[Dr. Rehan Quadri]
I put the ICE in the left groin.
…
[Dr. Rehan Quadri]
The first thing I do is I evaluate the clot and I establish a baseline because I want to make sure that I got the entirety of it and there's nothing left.
…
[Dr. Rehan Quadri]
Since his issue was recurrent PE, recurrent infections, catheter malfunction, I was like, "We actually need to clear the majority of this." We took several cine clips. Also, it's good to just get your landmarks down before you bring your catheter in because the one fear that we did have was that, if we break off the clot as the catheter is advancing in, that's not ideal. Using the ICE, we were able to, because on one hand, you could put a wire through the catheter, get a through and through access, and then the catheter would be directly in line when you bring up the FlowTriever, and then you could do your pulls that way.
There's a chance that the wire could knock off the clot. After doing 13 of these, the likelihood of that is not as high as I thought it was. In the first one, we decided to get a wire up very carefully with ICE guidance. We went into the right subclavian, it was a right IJTDC. Then that gave us a nice directionality along the course, and then we put in a 24 French Gore DrySeal. We used a 65-centimeter. He was a pretty tall guy. Then we advanced the catheter up over Super Stiff and Amplatz. The first wire we put in was the glide wire and then exchanged. The big thing with the ICE is that, so I just follow the traditional home view, and then go from there. I go up with the ICE catheter pointed anteriorly.
A good landmark as you're entering. For starters, since it's not over the wire, I use a 45-centimeter 9 French sheath. Our ICE is the 8 French catheter, but I like to have a little bit of room around it. Then once it comes up, I make sure the catheter's pointed anteriorly as it enters the RA. You can either use the eustachian ridge as your marker, which is this echogenic line that shows up, and then you should see the tricuspid valve. Then you know you're in the RA, tricuspid valve, and RV. One way you can confirm that, if you want to, is before you come up from the cava, you can confirm which direction turning gets you aorta and which direction turning gets you liver, and then you can set clockwise to be that way. So then you know you're going interatrial septum or ventricular septum relative to free wall. Then from there, if you are worried that you're going to break off the clot or you can't see the clot even with the standard rotation of the catheter without adjusting the torque or the posterior-anterior angulation, you can actually oftentimes just decrease the depth.
It's that the depth is so large that you're not seeing what's in the near field very well. Then there is also a gain function on the ICE catheters. In IR, we use it for TIPS mainly.
Either the rep's there or the tech's there and you're just like, "Can you fix this?" and they're just messing with and messing with it. I spent a lot of time before we did this case just getting comfortable with the settings.
[Dr. Michael Barraza]
That's what I need to do.
[Dr. Rehan Quadri]
That's what I really advise people to do. The IFUs are great, the videos are great. The cardiology literature has a lot of stuff out there.
[Dr. Michael Barraza]
The first time I did a TIPS with ICE, I didn't have anybody with me who'd done it before. The guy that came in for the case, I was like, "This guy's going to make this so easy." All he was there for was to turn on the system. He was like, "Oh, I've never actually seen one of these." I was like, "Okay."
[Dr. Rehan Quadri]
Honestly, the biggest mistake people make is they break it as they're plugging it in and it doesn't connect properly and it wastes so much time in the case. Just look at the device, look at how it connects and locks before you put it in.
…
[Dr. Rehan Quadri]
Then definitely put a sterile probe over it for this particular case just because you're going to be moving in and out quite a bit to adjust.
[Dr. Michael Barraza]
Are you doing angiography as well either in the cava or the heart or is this primarily using ICE guidance?
[Dr. Rehan Quadri]
Initially, we were afraid to pressurize because on the ECHO, their RVSP and their TAPSE was pretty high, unfortunately. We weren't sure if they could tolerate much of an injection. My colleague, Biona - she actually had done a case of clot in transit with the FlowTriever previously. She actually used TTE and had that same fear, and so it was nice to have her advice. Then, when we went up, we just thought it better to not inject yet and then see if we can get it all done with ultrasound. If we needed to, we would have. We did end up doing a gentle puff of saline under the ICE to see how the clot moved.
…
[Dr. Rehan Quadri]
We were like, "Is it going to pop off or not?" You'd be surprised every time the anesthesia was like, "Oh, I'm going to give him some more meds," you'd see bubbles showing up. In our head, I was like, "I hope that's not too many." We confirmed that he didn't.
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Clot in Transit in Patients with Shunts
It is imperative to conduct comprehensive pre-procedure assessments, including evaluating for any existing interatrial shunt or patent foramen ovale (PFO). Failure to do so can complicate endovascular thrombectomy and necessitate involvement of cardiothoracic surgery. Intraoperative imaging is just as important as pre-procedural planning and when performing a thrombectomy on clot in transit, be sure to look for what Dr. Quadri calls the “Shamu” sign.
[Dr. Rehan Quadri]
That's another thing on the pre-op ECHO, you really need to confirm that they don't have a significant shunt, an interatrial shunt.
[Dr. Michael Barraza]
That's very important. I meant to ask you that, in either a shunt or just a flat-out like a PFO, are you looking for that before you start doing these?
[Dr. Rehan Quadri]
100%.
[Dr. Michael Barraza]
What do you do if there's a shunt?
[Dr. Rehan Quadri]
There was a PE that one of my colleagues had to do, and in fact, there was a clot already across the PFO-
…
[Dr. Rehan Quadri]
-plugging it and it was hanging on the other side.
…
[Dr. Rehan Quadri]
They went up, got the PE out, and then it went to cardiothoracic surgery and they had to close it up. The problem with closing it beforehand if they have significant PE, so there's an interventional cardiologist and aN ICU attending that I work very close with on our PE response team and that team also, it's more like a VTE response team. We basically look at all high-risk DVT and all high-risk PE. We talked it through and there's not a lot of literature on it because I guess after the COVID era, the volume of PE has drastically increased. We see a lot of these shunts that open up and if you close it, they might go under right heart failure because that's partially decompressing the pressure.
We discussed with Luna, who's the structural heart specialist about closing them and he said, "I don't know if that's a great idea. We'd have to really look at it case by case." He has definitely helped me out when we were trying to do bubble studies in the procedure as well.
[Dr. Michael Barraza]
It's probably also hard to gauge what the hemodynamic outcome of that is going to be when a lot of these patients also have big PEs. That's got to be challenging. When you're actually doing the thrombectomy portion, when you're aspirating, how are you evaluating that you got the clot?
[Dr. Rehan Quadri]
We finally line up the ECHO probe exactly where we want it. Then the one thing I will say is you want to rotate the ECHO to where your position is, and then rotate it just a little more and then it'll slide right back into place and somebody just has to man that. Usually, the fellow is just holding that in place. Then from there, you make sure that your wire is in the trajectory of the clot with the ECHO. You see it in the same plane, you like the angulation, and then we'll also do fluoroscopic continuous guidance as it's coming up. I described this actually. It's funny, I actually said this to Devin once, I call it the “Shamu” sign.
You just see the Inari pop up all of a sudden. It's just this huge, hunking thing coming up and it's almost like Shamu launching over the rocks. It always makes me just say, "Goddamn it, hell yeah." Just when it's pointed right at it right off the bat, you save so much time. You feel great, you know your pull's going to be successful. The first case we had that Shamu sign, and then we hit it, we ripped it, and the entire thing launched out
…
[Dr. Rehan Quadri]
The fibrin sheath along with the lollipop clot.
Clot in Transit with Concurrent Pulmonary Embolisms
If clot in transit and pulmonary embolism (PE) are present together, Dr. Quadri states that you should treat the clot in transit first, unless the PE is massive, in which case it should be attended to first. Equipment may change when dealing with clot in transit alone versus clot in transit with concurrent PE, but it is the preference of the operator. It is important to be aware of and prepare for what could go wrong during clot in transit treatment. Before beginning and after thrombectomy, it is important to check the pulmonary artery (PA) pressures and right ventricle (RV). At the end of the procedure, confirm that no clot or sheath is left before removing the instruments and achieving hemostasis.
[Dr. Michael Barraza]
Oh, cool. After that, you're looking under ECHO and seeing everything's there and it's gone and you're cheering and everyone's proud of you and it's great. What if you have to do a PE too? What order are you doing it? Is it clot in transit first or PE?
[Dr. Rehan Quadri]
Exactly, the clot in transit first if the PE is not massive. If it's massive, then we go with the PE first. Very frequently, the clot in transit can be obtained with your wire position in the pulmonary arteries, to begin with. Access is key here. We're sticking everything we can for backup situations if necessary. Sometimes I'll even stick the left GSV and have a pigtail in the pulmonary artery as we're doing the case.
…
[Dr. Rehan Quadri]
I forgot to mention this, but we always check the PA pressures prior to starting. We'll check the PA pressure, we'll check an RV pressure, and either we'll use a Swan-Ganz balloon float technique or not over the wire form pigtail push up to the PA and do that traditionally in the beginning after we've done our ICE evaluation of the clot.
[Dr. Michael Barraza]
Do your equipment selection change if you think you're going to be doing both or if you're just going to be doing the clot in transit?
[Dr. Rehan Quadri]
I like the 24. I'm almost always putting in a 24 for a PE case. I feel like the 24 flex has the best trackability and through that, I'll just telescope 16 or I'll even put in a 20 curve. Even for the clot in transit cases, sometimes we put in a 20 curve giving up the wire, got it pointed right where we wanted it, and pulled off some pretty chronic stuff. Yes, I always start with the 24 flex. There is the new Protrieve sheath, which is interesting.
…
[Dr. Rehan Quadri]
Yes, it's nice, especially for filter retrieval. Dr. Khaja actually used to do something similar at UVA. He would partially deploy a wall stent when we were doing cava cases. I haven't found an instance of it where I would use it in an in-transit clot that was already at the level of the heart.
[Dr. Michael Barraza]
Right, because you may be going after stuff in the PAs anyway.
[Dr. Rehan Quadri]
Exactly, but if it was below the level - so there was one case where it was going from the hepatic veins into the RA and I thought maybe we could have gone in with the Protrieve sheath, encased the clot in that funnel, in case it broke off, and then also just been directly in line, and done a pull, and you can do a pull through the Protrieve sheath as well, which is nice. That's the only other addition, but usually, it's 24 French Gore DrySeal, bilateral groin access, at least, if not an IJ.
Then, we dissect out the catheter, just in case, and we're ready to go with potentially putting a wire through that if we need to. Then a 9 French sheath for the Acunav. Then if we do an IJ access, it's usually a 6 French sheath for a pigtail.
[Dr. Michael Barraza]
What happens next? You get the clot out of the heart, maybe PAs or not, where do you go from there?
[Dr. Rehan Quadri]
Everybody else in the room starts taking the most number of pictures I've ever seen in my life at that moment and it drives me crazy. They're just snapping photos talking, but that's the most stressful moment for me. The first thing I do is I measure the PA pressures and I make sure that they haven't changed. If I need to take an RV pressure, I'll take an RV pressure. That's when I will usually inject. After I've confirmed with the ICE that there's nothing hanging around that I'm going to break off. Even at that moment, sometimes you can inject through the catheter. If you feel really comfortable and you want to see if there's any sheath left because that sheath is stuck, it's not coming out.
If you pulled off what we call the lollipop at the end, the rest of it is going to be there. You can more comfortably potentially inject through there, but I do usually inject through the Inari from below and maybe even the Gore DrySeal. Then if I have a pigtail and the PA, I'll also do a PA-gram. Once that's all good, then it's all about hemostasis or exchanging the catheter, one of the two things.
Dr. Quadri’s Most Challenging Case
Dr. Quadri recounts one of his most challenging clot in transit cases which involved the removal of a 1.8-centimeter clot from the right atrium of an elderly female patient. The case was particularly complicated due to concerns about suction strength collapsing the atrium wall. Such an event would lead to a complete loss of venous return and subsequent cardiac failure. After consulting with colleagues, the perceived risk of collapsing the atrium wall was deemed low and Dr. Quadri successfully removed the clot. The case emphasizes the importance of thorough planning, coordination, and cautious decision-making in high-stakes thrombectomy procedures.
[Dr. Michael Barraza]
One more question I've forgotten to ask. Have there been any particular cases that were especially challenging for one reason or the other? We talked about clot along the walls. I would imagine those are probably harder to get out in something that's just sitting along a TDC.
[Dr. Rehan Quadri]
Yes, so the hardest case we had was, she was an elderly female that had had a port for about three or four years and the port had a 1.8-centimeter clot at the end of it. It wasn't really mobile, it was almost stuck to the RA wall, and so two things came to mind. One, I was afraid of suctioning on the wall, and then collapsing the RA or potentially pulling out the volume of the RA. In a male, an adult male, your RA is 60 to 120, maybe even 160 in volume if it's super dilated on the ECHO.
If you do a 60cc pull, you're probably not going to dump all the volume realistically and the volume is not as big of a deal when I was talking to Huffman about it because with AngioVac, he's like, "We're just continuously pulling." They do have the circuit putting blood back in, but at times if it's not matched, he's like, "You're usually still fine." Then the bigger fear is that, are we going to collapse the RA walls and potentially send him into a complete loss of venous return and cardiac failure? When I spoke to Huffman, he was like the likelihood of that happening is extremely low.
We looked at the force and the suction of the catheter and even though it's extremely strong, collapsing the walls would be very, very difficult. Just with the sheer size and morphology of the RA. Not saying that it's not theoretically possible and not saying that I didn't freak out about it, we did. One way around it for this case is I intentionally used the 20 curve. We took the ICE from the contralateral IJ, down in, visualized the clot, and we saw where the length of the catheter was and where it terminated. Then I went up with a wire up the ipsilateral IJ, took the 24 up, took the 20 curve up, unsheathed it.
The hardest part about this case was timing the unsheathing of the catheter and keeping it steady once it was pointed at the clot. Because the RA is, in this female, even though she was elderly, relatively small female, you would think it's smaller, but her RA was actually pretty dilated. It was like trying to find a needle in a haystack. Finally, you have two fellows holding one sheath, another fellow holding another sheath, I'm angling it this way, and one person's holding the ICE. It's just like pull, pull, pull, and you're just like, of course, there are several pulls without the clot in it. This case, the key to me being able to even accept it was the fact that we had the flow saver FlowSaver.
I was able to give her all the blood back. Prior to that, when I did cases as a fellow and watched Dr. Kaja, he was so careful about the number of pulls, where he pulled, how much volume he took. There was always blood in the room. I always have two units in the room no matter what, anyways. I would say that case was so challenging just because every device that you have in there interacts with the other device. It can sometimes prevent or help your catheter be forced in a direction.
The key was just getting our wires angled correctly, getting our catheters angled correctly, and pushing whatever we needed to. Sometimes people even inflate a balloon alongside the Inari to push it in a direction. That's, I guess, why that case was pretty tough, but we got it in the end.
[Dr. Michael Barraza]
That's what counts. What else do you want to talk about that I didn't cover?
[Dr. Rehan Quadri]
I guess the thing that I've learned at the end of this is, and I'm obviously pretty new at this whole attending gig being only two or three years out, which is the thing I love about UT Southwestern. You have so much support. We have senior and junior people who have everyone's back. We all team together. It was like two or three attendings in every case, two or three fellows. The indications for this procedure can get very vague because a lot of catheters and devices and people will have what looks like a suspicious clot. The literature goes one way or the other, particularly on the free-floating clot. It used to be thought that it's going to break off and go somewhere.
Realistically, a true clot in transit, you're more likely to see in somebody with tricuspid stenosis. In reality, something stuck somewhere. Is it really worth it to put them through this and go through this procedure? Yes, it's a step down from AngioVac. That was the whole point of why we created this; to give an alternative, but what I found the best indications were recurrent PEs, recurrent infections, recurrent catheter malfunction, and somebody with a very bad cardiopulmonary status where they really couldn't afford to have that clot break off.
I guess that's the message that I want to convey. You really just have to look at the case and look at whether or not you can get away with just pulling the catheter and heparinizing them or do you really need to go through this entire process?
[Dr. Michael Barraza]
Right on, man. Look, this was awesome. Thank you for joining us and thanks for going through this with us. This is something new for me. Thanks to our listeners for tuning into another one of these and we'll catch you on the next one.
[Dr. Rehan Quadri]
Perfect. Thanks for having me, I really appreciate it.
Podcast Contributors
Dr. Rehan Quadri
Dr. Rehan Quadri is a practicing interventional radiologist and an Assistant Professor in the Vascular Interventional Radiology division of the UT Southwestern.
Dr. Michael Barraza
Dr. Michael Barraza is a practicing interventional radiologist (and all around great guy) with Radiology Associates in Baton Rouge, LA.
Cite This Podcast
BackTable, LLC (Producer). (2023, February 6). Ep. 289 – Treating Clot in Transit [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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