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BackTable / VI / Podcast / Transcript #35
Podcast Transcript: Over-the-Wire Technique for IVC Filter Placement
with Dr. David Mobley
Dr. David Mobley of Columbia University VIR describes his over-the-wire technique to prevent tilting in IVC filter placement. Special thanks to our sponsor Argon Medical. You can read the full transcript below and listen to this episode here on BackTable.com.
Table of Contents
(1) Developing A Technique For Improved IVC Filter Placement
(2) How does over-the-wire technique compare to traditional IVC filter methods?
(3) How do I deploy an over-the-wire IVC filter?
(4) What is the best access point to use when using OTW IVC filter guidance?
(5) When do you bring patients back for filter retrievals?
(6) Minimizing Filter Tilt During Bentson Guidewire Removal
(7) Do you do a repeat cavogram after OTW filter placement?
(8) What type of wire is used for the OTW filter placement?
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[Michael Barraza]
This is Michael Barraza, welcoming you to the BackTable Podcast. BackTable is a resource created by IRs for IRs to connect with your colleagues and learn tips, techniques, and the ends and outs of the devices in your cabinets. Download our free iTunes APP to access our previous episodes, blog posts and procedures specific content and help you grow your practice. I'd like to begin by thanking Argon Medical for sponsoring today's podcast. Argon is a manufacturer of the Option elite IVC filter, which is currently the only filter on the market indicated for over the wire deployment. And that's what we're talking about today. I'm joined by Dr. David Mobley from Columbia University in New York Presbyterian. Welcome, and thank you for joining us.
[David Mobley]
Thanks for having me.
(1) Developing A Technique For Improved IVC Filter Placement
[Michael Barraza]
I was hoping you could just start by telling me a little bit about your IVC filter placement and retrieval programs at Columbia.
[David Mobley]
It's pretty standard and it follows the recommendations by the Society of Interventional Radiology guidelines. It's put in when indicated and there are several indications for placement and obviously filter. We try to remove them as soon as possible when it's indicated and when the patients are able to have them removed.
[Michael Barraza]
Okay, and so I've read a poster you guys did on a placing the Option filter over the wire. Could you tell me a little bit about that?
[David Mobley]
Sure. For years we've been placing filters in the IVC and we've been placing them jugularly and femorally like the rest of the country. The Argon Rep had come to me and said, ”Listen, we've got this filter which we had been using for awhile." And he said, "This filter is the only one that has a hole right through the middle.” He had this idea of placing it over the wire with the wire extended all the way into: either the femoral up into the SVC, or jugularly down into the Iliac vein, and deploying it with that wire extended all the way distally.
There has been some contention with the placing and tilting of filters within the IVC. It's believed that tilting of the filter makes it less effective in its protection from DVTs and creating pulmonary embolisms. Also, it's believed that the increased tilting makes it more difficult to remove depending on how long it's been in. We had placed many of our filters through jugular and transfemoral access points. When Mike came to me and made this suggestion, I listened to him and talked to him about the technique.
I tried it a few times and it worked out very nicely and I said, “alright, well let's take a look at this.” So we did. I believe it was around 39 patients and we looked retrospectively at those patients, and the 40 patients prior to that, that had been performed with transfemoral access. We looked to see if there was a difference in tilting and it showed a statistically significant difference in tilting between the filters placed over the wire and not over the wire.
[Michael Barraza]
I have used a lot of these filters and I haven't done them with a wire. Would you mind walking me through, start to finish, how you would place this over the wire?
(2) How does over-the-wire technique compare to traditional IVC filter methods?
[David Mobley]
Here at Columbia we place a lot of different types of filters. So we didn't know if there was a difference between the Option versus the Option compared to Option versus all comers. So what we did was we looked at all of the filters that we put in not over the wire, and compared to the Options we put in over the wire. There was a statistically significant difference between the over the wire and the not over the wire for tilting. We then stratify it out for Option versus Option. Again, it showed a statistically significant difference between over the wire and not over the wire. So that was really interesting.
[Michael Barraza]
I didn't catch that point when I read the poster. And the other thing I forgot to bring up is, it noted an increased procedure time and increased fluoro time. However, in my opinion, that time you probably save when getting these filters out and not having to deal with that tilt.
[David Mobley]
Right. The time difference it showed was statistically significant. It didn't show a statistically significant amount of fluoro dose. That was really a little bit of getting used to the procedure and technique and getting the wire up into the SVC. So, it really didn't add too much time, although it showed a statistically significant difference, the dose wasn't that much.
[Michael Barraza]
And again, yeah, just think about the time saved. Not having to go through advanced retrieval techniques. I think you get that time back over and over.
[David Mobley]
That's the belief and that's what we're looking at in the coming future. We expect to make that time difference up in the retrievals.
(3) How do I deploy an over-the-wire IVC filter?
[David Mobley]
The Option filter comes with a deployment sheath, a dilator, and it comes with a pusher that has a wire extended from the end of it to about 10 centimeters beyond the end of the pusher - that wire already goes through the end of the filter on the end hole of it. So, you already have a wire going through it. We get femoral vein access with ultrasound guidance with the Micropuncture set, and we put in a Bentson wire up and over the Bentson wire we place the Argon Sheath. We then do an IVC-gram, so that we see where our renal veins are, and the confirmation of the IVC.
After that, we put the Bentson wire back into the sheath with the dilator and we get the exchange length Bentson up into the SVC. We then move our sheath up into the appropriate level at the level of the renal veins. We leave the SVC access with the exchange length Bentson. We remove the dilator from the sheath with the sheath in the proper positioning. That dilator then comes all the way off the wire. We then place the filter on the wire, being very careful to gently put the wire through the end of the filter deployer. You do this while holding your finger at the end filter deployer, so that when you push that wire through gently, it doesn't actually push the filter out the end of the deployer. Once you do that, you grab the wire, you put your fingernail on the end of that deployer and you bring the deployer all the way up to the sheath. You place the deployer into the sheath until it locks. And instead of using the pusher, you actually use the original dilator that you put in the sheath with, and you run that over the wire and you use that as the pusher.
The original pusher has a wire coming out the distal end and it has a plastic sheath used as a pusher. What we're using instead of one piece of equipment is two. We're using an exchange line beds and we're using the original dilator as the pusher. We maintain back tension on the Bentson wire making sure it's still in the SVC, and that's a little bit of the added time, just making sure that wire hasn't moved anywhere. Once we confirm that that wire is still in the SVC, we look back down into the abdomen, we use the pusher to advance the filter up into the deployment area, and we maintain forward pressure on the dilator and the wire. We then unsheath the filter in the position that we originally wanted it to be.
[Michael Barraza]
Got it. So it's just the wire, it's like a stabilizer, that maintains the straight position?
[David Mobley]
Exactly. The dilator that we're using as a pusher is keeping it in the position as you're unsheathing it and the wire's keeping it stabilized in the longitudinal frame compared to the IVC.
(4) What is the best access point to use when using OTW IVC filter guidance?
[Michael Barraza]
Okay. That sounds fairly simple and easy. My understanding is that you should be able to do this from really any access that you could place the filter from as long as you have that straight longitudinal course.
[David Mobley]
Absolutely. We tried it once or twice from a jugular access, and we tried it from both femorals. However, when we were looking at this, we really just wanted to study it from one area that most people use in the country. That's either the right jugular or right femoral, and since the femoral seemed to have more tilting, that's what we decided to compare it to.
[Michael Barraza]
Is this the primary filter you guys are using or it's just a good mix?
[David Mobley]
We used to have a more of an even mix between all the filters that are out there, but with this study and working with it, we are definitely primarily using Option filters. However, we are an academic center, we train residents and fellows and they need to understand how to use different filters, and how they feel, and how they deploy. We do have a little bit of a distribution between various filters, but primarily we're using Options.
[Michael Barraza]
Okay. And when you're placing them personally, do you prefer to do them over the wire?
[David Mobley]
If I go femorally, I do them over the wire. If I go jugularly, I don't go over the wire.
[Michael Barraza]
Okay. This sounds pretty straightforward and very doable. I'm going to hopefully be doing one in the next week or two. We do a surprisingly large number of filters and I’d like to be doing more retrievals, which brings me my next question. When you put these in, I guess it always depends on the indication, but when do you typically have patients come back for the retrieval?
(5) When do you bring patients back for filter retrievals?
[David Mobley]
Again, it depends. We try to get them back within three to six months, sooner than that is even better. But generally speaking, with the patients that we have here, whether it's postsurgical or whatever it happens to be, they tend to need a higher level or a longer follow out with their treatments. For us, even though we'd like to catch them before three months, we usually catch them when we do and I'd say between three and six months.
(6) Minimizing Filter Tilt During Bentson Guidewire Removal
One of the most important things for the deployment is once your filter is deployed, you'll see that it's very stable in the IVC. So what you have is, you have a sheath that's been pulled down, it's usually a couple of centimeters below the deployed filter. Your dilator will be pretty much within that sheath, or just a little beyond, or maybe a centimeter below the lowest level of the legs and you'll still have that wire up into the SVC.
One of the most important things is the removal of that wire through that filter. What you do is you keep tension, and keep the dilator, and sheath right where they are, and you gently pull down on the exchange length wire that you have. Usually, it comes out with no tension, very easily.
Every once in awhile, the very small micro loops that these steel Bentson wires are made of can get caught and cause friction on the edge of this filter. And so under fluoro, you'll see that the filter is pulled down and you'll feel that tension pulling down. If that happens, what's happening is, you've got show us enough of a tilt for there to be friction on the edge of the filter and the wire.
What you need to do is, keep that sheath in the same place. Push the dilator up into the sub apex where the wire goes in inferiorly through that hole. It supports the filter and just puts it off its axis, so that it takes that tension of the Bentson wire edge off of that. And I've never not been able to pull it out easily.
[Michael Barraza]
That makes sense. With the position of your sheath, it's not going to displace the filter either.
[David Mobley]
It doesn't. It's just a touch of tension, just to push it off to get it off its axis. That's probably the crux of the very end because you're deployed, you're done and you start pulling and then you can definitely pull down, and causing extra tilt on that filter.
[Michael Barraza]
All right. Out of curiosity, do you do a repeat cavogram after filter replacement?
(7) Do you do a repeat cavogram after OTW filter placement?
[David Mobley]
I do them regularly, yes. I did it every time when we were doing the study. Some of my partners do it and some of them don't. I routinely do whether I go juggularly over the wire, not over the wire, transfemoral … I routinely do a post-positioning a cavogram.
[Michael Barraza]
Okay. All right. Was there anything else you'd like to cover?
[David Mobley]
No. I think that's it. Just a reminder that we did stratify for the non-filters over the filters. It is on the poster. It's in the section under the results where we compared Option to Option, and it did show still a statistically significant difference between tilting with and without over the wire using a transfemoral approach. But if you are going to go transfemoral, I would use over the wire even if the IVC looks “Straight”. I'm sure you've been in a situation where it looks straight, it pops out, and then it just bends right over.
[Michael Barraza]
Yeah.
[David Mobley]
The interesting thing is, we did all except for one of our filter placements from the right. If you go right, there was a statistically significant difference in tilting toward the left. You have that angle that's going and it's bending over against the left side of the IVC. From the left, it tilted over toward the right. Even though there was only one and we didn't have any power to compare the two. It just makes sense that you come in from the right, it bends over, it's leaning oftentimes to the left side of the IVC and that's the side they tilt on. That being said, if I go femoral left or right for any reason, I go over the wire.
[Michael Barraza]
I'm going to give it a try. We are doing a lot of filters where I am now and I may be able to do it next week.
[David Mobley]
If you have a fellow or if you have an assistant that can hold the end of that wire and knows how to give back tension so it doesn't move, then you really shouldn't have a problem, it shouldn't add extra time. You'll do it once or twice and then honestly, you probably won't see a difference in time. It'll just be checking it when it goes a little higher or lower just to make sure it's in that right space and then deploying it. And then again, getting used to that before you pull that wire out, fluoro it, and watch it as you're pulling for any tension. I've even put the dilator and the sheath up to un-angle the filter, just a touch, and that wire will come right up.
[Michael Barraza]
I'd be interested to see how large the hole is. If it will only fit. Is going to fit an 0.035, or could you put an 0.038 wire in?
[David Mobley]
I think you can put an 0.038 wire in.
[Michael Barraza]
Interesting.
(8) What type of wire is used for the OTW filter placement?
[David Mobley]
I tried a few of them with the stiff Amplatz and the exchange length, and it worked just as well. I didn't see any difference. Since I had already started with the exchange Bentson, I just kept going with that. But the stiff Amplatz works very nicely as well.
[Michael Barraza]
That's awesome. It's an innovative, useful technique. I look forward to doing it myself. I also look forward to seeing the rest of the data that comes out as you guys look at the retrieval times as well.
[David Mobley]
Yeah, we're looking forward to that.
[Michael Barraza]
And lastly, I'd like to, again, thank Argon Medical for sponsoring today's podcast. Again, the Option Elite filter is the only one on the market currently indicated for over the wire deployment. Thanks everyone for listening in.
Podcast Contributors
Dr. David Mobley
Dr. David Mobley is a practicing interventional radiologist at Columbia University in New York.
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). (2018, November 12). Ep. 35 – Over-the-Wire Technique for IVC Filter Placement [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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