Chapters Transcript UBA1 Genetics Course: 2nd International VEXAS Workshop Thank you, uh, and good morning everybody, and thank you for the privilege and honor of the invitation to discuss intravena cava filters with all of you today. Um, these are my disclosures. So just to start, all of this is born of the issue of acute deep vein thrombosis and pulmonary, pulmonary embolism. And really, probably the most important point to hammer home is that anticoagulation is the mainstay of treatment. Filters will always be a secondary consideration, at least in today's practice. Regardless, there's always been a recognition that sometimes you want to prevent a lethal complication of a blood clot propagating from the lower extremities or elsewhere to the lungs and causing, uh, causing significant cardiopulmonary compromise and possibly death. So the concept of vena cava interruption was started. Uh, initially surgical ligation. Here's an example, a CT scan, cross sectional imaging with the Deuis clip, uh, which allows some flow through it. It was put in using open surgical techniques. In the 70s, the permanent filters came along, and then in the 90s, the retrievable filters came along. So, when do we put them in? Really, it's distilled down now to the situation where there's a contraindication to anticoagulation. Perhaps there's a bleeding issue. You can't anticoagulate them, and they do have a blood clot, so you might need to consider putting in a, a filter. Uncontrolled active bleeding. We're frequently consulted about this ourselves as well as the interventional radiologists when there's a GI bleed or, etc. You can't anticoagulate them. They have a DVT, um, and certainly the situation of acute hemorrhagic stroke. Some other secondary situations, these used to be more common. Many have ultimately been debunked by the literature, but a complication secondary to anticoagulation, this is sort of an unusual thing, failure of anticoagulation. Even more rare because you always wonder if it was being taken correctly, etc. And then the relative indications, I think many of which have almost completely fallen out of favor of the massive PE, the very scary appearing on ultrasound free-floating thrombus, whether it's in the femoral vein, the popliteal, etc. Multi-trauma, where filters used to be put in routinely, now are never put in. The bariatric population, similarly. Um, so, you know, that a lot of, there are a lot of stakeholders that deal with thrombosis and intravenous cava filter placements. Uh, and, and you can see the variety of societies that have published guidelines on this from the American College of Radiology, Interventional Radilogy, the American Heart Association, College of Chest Physicians, across the pond, the British Committee for Standards in Hematology, and the European Society of Cardiology. So just in terms of some technical considerations, I am a vascular surgeon and proceduralists, um, you know, kind of know this almost intuitively now. Uh, in general, if you have the luxury of having axial images ahead of time, it's good to look at them. That way you might avoid some of the anatomic anomalies, some of them that Dr. Blomberg went over this morning, such as the left-sided intravena cava, so that you deployed in the correct location. The one that we commonly see actually is the mega cava, the intravenous cava that's larger than 30 millimeters in diameter where you might run the risk of, of IVC filter migration if you deploy it in an undersized filter. Uh, the approach, generally, and it's not a rule, but generally jugular is the first choice because it results in the least amount of tilt. It's the straightest shot. A lot of people placed them routinely from the femoral orientation. And they get reasonably good results with that as well. Um, there's also the potential for, and it's a little bit less our practice here, but in certain situations in ICU care where you can put them in at the bedside with intravascular ultrasound guidance for somebody who's too sick to be transported to the interventional radiology suite or to the operating room. In general, when you deploy it, you want to try to deploy it straight without significant tilt of more than 15 degrees. And there are instances, you know, we always place it in the infrarenal location below the renal veins. There are always instances, or sometimes there are instances when it's appropriate to place it above the renal veins, such as in pregnancy where you want the filter to lie above the, the gravid uterus, or if the whole IVC is thrombosed and you're forced to place it above anyway if the clinical situation. Uh, indicates it. So, what are these filters? Probably the most commonly implanted filter in the world, uh, historically is, is the Greenfield filter. I'd have to go back to see what the numbers are, but I think there are at least 20 million Greenfield filters that have been implanted, possibly more. Uh, these are some of the other ones, uh, that are out there, and they're not just for historical purposes. Often when we encounter patients with potentially an IVC filter complication. You almost have to be able to recognize these filters radiographically, so that you might know how to approach them, if, if you want to treat them. The one interesting one radiographically is the bird's nest. It almost looks uh like a fractured filter, if you look at the imaging, cause you don't see any of the wire mesh, only the two triangular components. And so, just be mindful, it's probably not a fractured filter, it was just a bird's nest that was implanted a while back. Then you have the retrievable filters, and, and I'll go a little bit into this and, and some of the data that might push the use of retrievable filters, uh, to more or less usage uh for the treatment of DVTs. Um. But this is what we're talking about. These are some of the common ones that are out there and some of the iterations of them. Uh, this is the Cook Select is the most recent iteration from that company. This is the Argonne Option Elite, the Bard Denali, which is the most recent iteration of that. And the Otis, and anyone who's dealt with retrievals knows that ease is probably not the most accurate terminology for it, but, um. The one unique thing about all retrievable filters, they're pretty much the same filters that were placed permanently, plus or minus, but they all have some kind of hook on them. The idea being that you can, you can potentially grab them using interventional techniques. So, what are all the data driving some of the points that I made before? There aren't many data, and there are varying degrees of data. There are a number of case theories out there, but in terms of level one evidence, which is considered the gold standard in, in what we do and, and how we evaluate and come up with guidelines and recommendations. Uh, there's really been only one or one two-part randomized control trial called the PREPIC trial. PREPIC in French, and, and I can pronounce this in French, but, but I won't, but basically, uh, relating to prevention of pulmonary emboli by interrupting the cava. Uh, it was, it was led by a group in France, uh, and it was a randomized controlled trial of 400 patients with 4 different filters that were used. And the two groups that were randomized, one was treated with just blood thinners or anticoagulation, the other one with anticoagulation plus filter. So in the first, in pre-PIC one, which they were trying to identify early evidence of PEs, right? That's the ultimate thing we're trying to prevent the blood clot breaking off and going to the lungs. The anticoagulation group did have a slightly higher risk of PEs compared to the anticoagulation plus filter group, but it wasn't statistically significant. Very interesting. Pre-PIC 2, which was the longitudinal follow-up at 2 and 8 years, ultimately showed that anticoagulation plus filters had fewer PEs but more DVTs. So prevented blood clots from going up to the lung. But maybe the filters got clogged. Maybe there was a little bit more sluggish flow because the filters were in place and that predisposed, you know, based on Verkow's tribe that you heard earlier with stasis, predisposed to more DVTs. But importantly, there were no survival differences, and I think this kind of informs the the the decrease in usage of. Filters compared to what was done historically. I mean, I remember we used to place filters at least a couple a week, uh, routinely, and that was in a relatively small filter-based practice and that was spread across the institution and per faculty. Now I think we put in one every few months at at the most. It's, it's just a, a rare thing although there are still indications and it's still being done. So why do we need retrievable filters? The big argument is that these things can also cause complications. So not only are they not super effective based on the randomized control trial, they cause complications. So this is just sort of an interesting case report that we put out from here, where one of these tis filters. had slipped up from the renal infrarenal location to above the renal veins and thrombosed. So we had to go in, suction it out, smash the filter to the side, and then we were able to restore blood flow. And, and the issue with this is that when it flies above the renal veins, and, and it's the reason why we place filters below the renal veins, is it put the patient into renal failure. Interestingly, even though we cleared, after we cleared everything, The patient's renal function improved completely. He went off hemodialysis and his creatinine returned to normal, even after 3 weeks of uh of this uh extensive blood clot. So it's pretty interesting and, and that's why we published it. Other things that can happen, it can migrate, fracture, um, and embolize to the heart, which can sometimes be catastrophic. Uh, it can perforate adjacent organs. This is sort of the picture that no endoscopist and no interventionalist or vascular specialist ever wants to see, where you see a tine of the filter prong inside the, the duodenum on endoscopy. Uh, and then, so, so the unintended consequence though. Of all of this is that because they were retrievable, you know, you want to prevent this, but people said, oh, let's just put them in, we can take them out, it's no big deal. So for a period of time that did lead to an increase in uh filter placement, the expansion of indications, trauma, bariatric, again, a lot of which has ultimately been debunked. So what happens when you actually want to retrieve these things? Um, In general, retrieving a filter, if done. routinely and done in an appropriate time frame, and I'll go into that as well, is a relatively straightforward procedure. People like to show off about how quickly they can retrieve a filter. I can do it in 90 seconds. I can do it in 3.5 minutes, etc. in a straightforward situation, putting a snare, grabbing, engaging the hook of the filter with the snare, and, and taking it out is straightforward. In a small percentage, maybe 5%. It gets challenging. And so you have to be prepared potentially with an extensive toolbox where you start putting in big devices, so 1416, 20 franchis. If you're not familiar with the French system, you divide by 3. So a 20 French device is roughly 7 millimeters in diameter. So these things are big harpoons that you're putting into veins so that you can ultimately use big balloons. Graspers, whether they're flexible or rigid graspers, you can use adjunctive imaging to help you try to get it out, and I'll get into some additional uh interesting tools that are out there. But in general, a tough filter is a tough filter, and it takes a lot of work. These, it can turn a 3 minute case into a 3 hour or longer case, and it takes a lot of elbow grease to get these things out. This is just one example. There are many. Out there. This just happens to be a case where a patient of mine, where one of the filter prongs had gone out the side of the cava and the apex of the filter was similarly embedded into the wall of the cava. Ultimately I came in from two directions with two graspers, bent the filter in half, and took it out from the bottom location. And very interestingly, the inferior vena cava, if you do things. Judiciously can tolerate a lot, so there was no perforation, no thrombosis, but these are all things you have to be prepared for at the time of the procedure. Here's a device called the Cavaclear which in perhaps chronic filters or even potentially in routine filters, I think the utilization of this particular device is still being worked out, um, can help as well. Just kind of showing how the technology is being pushed forward. Oh, I don't know how that happened, sorry about that. Uh, it functions by ablating. And incorporated tissue circumferentially. Um, so from a multi-center trial that was recently presented at the Society for Interventional Radiology, the success rate is quite good in the selected patients that they had with a low risk of complications of thrombosis and, and perforation. And it allows you to maybe use a little bit less elbow grease because the laser does a little bit of the work for you. The main issue ultimately. I when you place a filter, and I think the majority of us, if not 100% of us now place temporary filters, we put in instructions to the patients to eventually come back, and a huge number get lost to follow up. And, and I think that that's, that's the crux. So theoretically it's nice to put them in. They're they're pretty easy to take out in those 3 minutes, but ultimately they get lost to follow up and you run into issues down the road. So, the FDA recommends that if the risk for PE has resolved, you should remove it within 29 to, you know, basically within a couple of months, preferably, you know, shortly after 30 days. Um, the retrieval rates though are heterogeneous. We know that most complications occur at greater than 30 days, and, and the risk of complications is non-negligible, especially when filters were really being put in at a, at a high rate, 1 to 1.2 to 5.1% in the Medicare population. Um. And so retrieval rates are quite abysmal, 12 to 45% in, in most, um, most series that are published. So a variety of places have published on quality improvement projects. Uh, people have employed databases in their IVC filter clin clinics, and that, you know, maybe you can go from 1/3 to 2/3 retrieval rates, interval mail notifications, etc. I think, uh, a significant amount of work is now trying to be you know, leveraging AI to do queries, etc. um, to determine who ought to come back to get their filters retrieved. So future directions, so what do you do when we're so bad at retrieving? A lot of technologies are kind of aimed at taking the retrieval part out of the process. So, filter and catheter combined systems, maybe in temporary settings in the ICU although that kind of fell out of favor. Uh, but, uh, the convertible filters is one, mechanical attempt where perhaps you don't want to deal with these challenging to retrieve filters and all you have to do is remove the top cap, and then it springs open into this kind of weak stent that Theoretically has no adverse consequence, but we're not entirely sure. There's another interesting concept of the bioconvertible filter. Or the, the sentry filter, where you have, uh, you see that little apex of the diamond there? It has an absorbable plastic type of segment that eventually absorbs over time, theoretically over 3 months, and then it just pops open after the 3 month time point. So you don't even have to worry about retrieval. But again, you're leaving these metal scaffoldings behind. We think it's OK. They didn't have adverse issues within, let's say the 1st 8 to 9 months of of the set of patients that they have, but we don't know the long-term issues. So the bottom line is, um. Is, uh, you know, with the guidelines, filters should be placed sparingly. Uh, for those that are placed, complications increase following the initial 30 days, and the focus should be on filter retrieval. Thank you. Published September 5, 2025 Created by
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