Updated: Apr 21, 2019
Inferior vena cava (IVC) filters are used prophylactically in patients with contraindications to anticoagulants in order to prevent pulmonary embolism. Complications of IVC filter placement, such as filter tilting, may decrease the filter’s ability to prevent pulmonary embolism. Dr. David Mobley discusses over-the-wire (OTW) IVC filter placement techniques using the Argon Option ELITE filter, and why this technique helps to minimize tilting complications.
The BackTable Brief
Designing an IVC filter with a hole at it’s apex allows for OTW guidance for filter placement.
Similar to traditional IVC filter placement techniques, the OTW technique can be performed at both femoral and jugular access points.
OTW placement of the Argon Option ELITE IVC filter is associated with lower rates of tilting compared to traditional filter placement techniques, says Dr. Mobley.
Dr. Mobley suggests the improved filter placement with decreased tilting may lower filter retrieval times.
Disclaimer: The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
Developing A Technique For Improved IVC Filter Placement
Successful IVC filter placement may be complicated by filter tilting within the IVC. Increased tilting decreases the filter’s efficacy in preventing pulmonary embolism. To circumvent this, Argon Medical designed an IVC filter with a hole at the apex of the filter to allow for OTW guidance and 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 of a 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 jugular and femoral 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 jugular 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 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 the rep 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.
How does over-the-wire technique compare to traditional IVC filter methods?
The Argon Option ELITE IVC filter demonstrates a statistically significant decrease in the tilting associated with over-the-wire versus non over-the-wire placement. Despite OTW techniques having less tilting, the procedure is associated with a slightly increased fluoro and overall procedure time. Although the overall procedure time may be increased, Dr. Mobley suggests the improved filter placement may decrease filter retrieval times on subsequent procedures.
[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.
How do I deploy an over-the-wire IVC filter?
Following femoral access, a Bentson wire is advanced into the SVC followed by sheath positioning at the level of the renal veins. The dilator is then used to push the filter into the correct position. Dr. Mobley recommends using back tension on the Bentson wire to maintain SVC positioning while advancing the pusher into the correct position. The dilator is used to maintain filter positioning while the sheath is removed. Ultimately, it is the wire that stabilizes the filter longitudinally while the filter is unsheathed leading to optimal placement with minimal tilt.
[David Mobley] The Option filter comes with a deployment sheath, a dilator, and a pusher that has a wire extending about 10 centimeters beyond the end of it. The wire already goes through the end of the filter’s end hole, 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 confirm IVC placement.
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 while leaving 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 length Bentson 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.
Dr. David Mobley is a practicing interventional radiologist at Columbia University in New York, New York.
Dr. Michael Barraza is a practicing interventional radiologist at Radiology Alliance in Nashville, Tennessee.
Cite this podcast:
BackTable, LLC (Producer). (2018, November 12). Ep 35 – OTW Technique for IVC Filter Placement [Audio podcast]. Retrieved from http://www.backtable.com/podcasts
The Materials available on the BackTable Blog 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.
The podcast referenced in this article was sponsored by Argon Medical Devices.