Inferior Vena Cava (IVC) Filters & IVC Filter Retrieval

Additional Info

• Audio File:uab/ua068.mp3
• Doctors:Gunn, Andrew
• Featured Speaker:Andrew Gunn, MD
• CME Series:Clinical Skill
• Post Test URL:https://cmecourses.som.uab.edu/mod/quiz/view.php?id=4615
• Guest Bio:Andrew Gunn, MD graduated magna cum laude from Brigham Young University in Provo, UT earning a BS in exercise physiology with a minor in sociology. He then returned home to South Dakota to attend medical school at the University of South Dakota. During medical school, he participated in the competitive Howard Hughes Medical Institute – National Institutes of Health Research Scholars Program and was awarded the Donald L. Alcott, M.D. Award for Clinical Promise. He graduated summa cum laude in 2009. He completed his diagnostic radiology residency at the Massachusetts General Hospital of Harvard Medical School in Boston, MA followed by a fellowship in vascular and interventional radiology at the Johns Hopkins Hospital in Baltimore, MD where he served as chief fellow.   
  
  Learn more about Andrew Gunn, MD
  
  
  Release Date: May 24, 2018
  Reissue Date: March 10, 2021
  Expiration Date: March 10, 2024
  
  Disclosure Information:
  
  Planners:
  Ronan O’Beirne, EdD, MBA
  Director, UAB Continuing Medical Education
  
  Katelyn Hiden
  Physician Marketing Manager, UAB Health System
  
  The planners have no commercial affiliations to disclose.
  
  Faculty:
  Andrew Gunn, MD
  Assistant Program Director, Diagnostic Radiology Residency Program
  
  Dr. Gunn has the following financial relationships with commercial interests:
  
  Grants/Research Support/Grants Pending - Penumbra
  Consulting Fee - Boston Scientific, Varian
  Payment for Lectures, including Service on Speakers Bureaus - Boston Scientific, Turemo
  
  Dr. Gunn does not intend to discuss the off-label use of a product. No other speakers, planners or content reviewers (Ronan O'Beirne, EdD, and Katelyn Hiden) have any relevant financial relationships to disclose.
  
  There is no commercial support for this activity.
• Transcription:UAB MedCast is an ongoing medical education podcast. The UAB division of continuing education designates that each episode of this enduring material is worth a maximum of .25 AMA PRA category 1 credit. To collect credit please visit www.uabmedicine.org/medcast and complete the episode’s posttest.
  
  Melanie Cole (Host):  Our topic today is inferior vena cava filters and IVC filter retrieval. And here to tell us about that is Dr. Andrew Gunn. He’s an interventional radiologist at UAB Medicine. Dr. Gunn explain a little bit about deep vein thrombosis or pulmonary embolism. What has been the standard treatment for these and the evolution from prevention of them?
  
  Andrew Gunn, MD (Guest):  So, both deep vein thrombosis, DVT and pulmonary embolism, PE, are classified as venous thromboembolism or VTE and what they are, are blood clots that exist in the veins and sometimes those blood clots can travel to the lungs which can block the blood vessels going to the lungs and that’s called pulmonary embolism. And what causes these are many things. Sometimes people who have cancer are at a higher risk for having pulmonary embolism. People who are immobile, either after surgery or because of trauma are at a higher risk and some people have certain genetic disorders that also places them at higher risk for forming these blood clots. And the most common treatment for these blood clots is to place people on blood thinning medicines, on anti-coagulation medicines. However, some people are not able to get anticoagulation medicine because they have either had recent surgery or cancer to the brain or they have been involved in trauma recently and in these cases; that is when we place an inferior vena cava filter.
  
  Melanie:  So, tell us about those filters. Are they removable? Are some permanent? Tell us a little bit about them.
  
  Dr. Gunn:  So, inferior vena cava filters or IVC filters are essentially a metal cage and they are placed through either a vein in the neck or a vein in the groin and they sit in that large vein inside the abdomen and block blood clots from going from the lower extremities up into the lungs where they can cause problems with breathing and with the heart. And so, previously, the first generation of IVC filters were not removable. As soon as they were implanted, they were supposed to be there for the rest of the patient’s life. But as we have come to learn, IVC filters themselves are not entirely benign and so newer generations of IVC filters come with hooks on them and so they become retrievable and so I would say the majority of filters that are being placed now are retrievable filters.
  
  Melanie:  And why do you need a retrievable filter and what’s the rationale for an aggressive approach to retrieving them?
  
  Dr. Gunn:  Well, as I stated, we are learning more and more that IVC filters themselves, when they sit inside the body, can cause problems. They can fracture. They can migrate from one location to another location. They, themselves can penetrate through the veins and contact the bone or an artery and they, themselves can actually cause blood clots or clots to form. And so, leaving something foreign inside the body that you don’t necessarily need isn’t always a great idea. And so, the idea behind retrievable filters is that we would provide protection for patients for a certain period of time when they most needed it, when they weren’t able to get anticoagulation, or they are most immobile; which allows us opportunities several months down the line, to be able to remove those filters and remove any of those negative consequences IVC filters can possibly have.
  
  Melanie:  So, what’s the excepted window of retrievability for these filters and are there some impediments to retrieval of the temporary filters?
  
  Dr. Gunn:  Yeah, I mean I think that window is pretty broad and a lot of that is going to be determined by the interventionalist’s experience and comfort level. We have pulled out filters as old as 13-15 years old. And so, I think any time that the filter is ready to come out; I think it’s worth trying to do the retrieval. Now the impediments to IVC filter retrieval can be that sometimes the filters tilt and those hooks can become embedded in the IVC wall. Sometimes, there’s clot up and down the IVC from the filter itself, from the patient’s underlying DVT and that can sometimes make the filter retrieval difficult. Sometimes the filters fracture themselves and so that can make retrievals themselves also more difficult. So, I would say those are the most common things that make filter retrievals difficult. But I think an aggressive approach in certain cases, I wouldn’t say in all cases, an aggressive approach is warranted. But in certain cases, an aggressive approach is warranted when a patient is having symptoms from their IVC filter. Either there is clot that has formed, and it is blocking off the IVC or the filter itself has penetrated through the IVC and is causing pain or some other symptom, in which case certainly an aggressive approach is warranted.
  
  Melanie:  So, that leads me to our next question and based on some of the symptoms the patient might be experiencing; how do you make the decision of your retrieval and what technique you are going to use?
  
  Dr. Gunn:  Well, the first thing, when a patient comes to see me in clinic to talk about IVC filter retrieval is I ask myself, if I saw this patient today, would I put a filter in. and if the answer to that is no, then I think that the filter – we need to discuss taking out the filter. And so that really drives a lot of my decision-making process. And as far as how we decide to remove the filter; that also depends on the type of filter. Some filters are designed with hooks on the bottom and so you need to come from the veins in the groin. Most filters are designed with the hooks at the top, so you need to come from the veins from above and sometimes you can see that there is either been fracture or it’s migrated in which case sometimes we have to come from both above and from below and get access with a wire through and through the patient to be able to stabilize that filter and to be able to retrieve it. So, most of those decisions about the technique and how we are going to do it is really on a case by case basis in consultation with the patient.
  
  Melanie:  Is there a learning curve for this Dr. Gunn and what would you want to tell a physician that is practicing this retrieval technique?
  
  Dr. Gunn:  Yeah, there is definitely a learning curve and I think when you are starting to remove filters; you are going to want to find filters that have been in for a short period of time, things that you are going to be able to retrieve quite easily and the more and more comfort that you get with that, then of course, the more and more aggressive you could potentially be with complicated filters. If you are a physician thinking about trying to do a retrieval, you are not going to want to start with a hook that’s embedded or that’s tilted or a filter that’s fractured. That’s something you are going to want to send off to a major referral center so that they can take care of that patient and so, the advice I would give is if you are going to start trying to do filter retrievals, is to start slowly and to start with the straightforward cases to make sure you have a lot of success under your belt before you start to attempt more difficult retrievals.
  
  Melanie:  Can you tell us something interesting about a particular case or diagnosis?
  
  Dr. Gunn:  Yeah, I mean one that sticks out in my mind, is there was actually a nurse that came to us from south Alabama and she had a filter in her for about seven or eight years and ever since she had the filter placed, she was having back pain. And so she went to get a CT scan and on the CT scan, they said she had colitis and you know, she’s a nurse and so she said, I definitely don’t have colitis and so she took the CT scan to another radiologist who noticed that one of the filter struts was protruding through the inferior vena cava and was digging into one of her lumbar vertebrae and so she assumed that that was the reason she was having back pain. She went to one physician to ask about filter retrieval, but the physician said that because it had been in for seven years that it could never come out. And she really advocated for herself and so she did some googling, looked online and she found an interventional radiologist who is actually a friend of mine in Chicago, emailed him and said heh, can we set up a filter retrieval consult, and he sent her back down over to us and we saw her here up at UAB and so we set her up and we removed her filter. It took us less than 15 or 20 minutes to do and instantaneously when she was in the recovery room, she said her back pain was gone. And so, I think it’s just a great example of number one, the IVC filters themselves can cause problems and then number two, you need to be your own advocate and then sometimes when you hear that this filter is not retrievable; you need to find your way to a center that retrieves a lot of filters to be able to discuss all of your options.
  
  Melanie:  What an amazing point and looking forward to the next ten years in the field, what do you feel will be the most important areas of research for implanting filters and possibly retrieving them? What does current research indicate for future developments?
  
  Dr. Gunn:  The biggest thing that’s going on with filters right now would be number one, we are doing large multi-center registries looking at retrievable filters because we don’t have the 10-20 years safety profile that we had with the permanent filters, so that’s currently ongoing right now. Number two, a lot of manufacturers are looking at either bioconvertible or bioconvertible filters which would be filters that would stay inside the patient, but say after 60 days or 90 days, they themselves would convert into essentially just a stent in the IVC and there would no longer be filtration of the blood. There are also filters where you can go in instead of retrieving the whole filter itself, you can pull off the cap of the filter and that opens it up and so you don’t have to remove the entire filter, you just remove the filtration portion of the filter. And so, I think in the next five or ten years, I don’t know what the role of those are going to be, but I think that’s where things are going to be going in the next five or ten years is these bioconvertible types of filters.  
  
  Melanie:  So, summarize it Dr. Gunn, because what a fascinating topic and what an interesting way that you are putting it and this decision-making process. Tell other physicians what you would like them to know about inferior vena cava filters and retrieval and when to refer to UAB.
  
  Dr. Gunn:  I think for physicians that are out in the community, they need to understand that number one, filters are mostly retrievable. There are a lot of physicians that still think that we are using these older type Greenfield filters that weren’t meant to ever come out. So, most filters that are going in today, are meant to be retrieved. And then number two, if you do have a patient that does have an IVC filter in and they are not being followed up by whoever placed the filter, it is really time to ask the question does this patient still need it. If they are taking anticoagulation medicine, such as Lovenox or coumadin or Xarelto or something like that and they still have an IVC filter; that’s really the time to refer the patient over to someone who can retrieve that filter because that filter is not doing them any good anymore, if they are already on anticoagulation and then the third thing is as I said earlier; the easiest thing to do is to ask yourself if I saw this patient today, would I put a filter in this patient and if the answer is no, it is also time to send that patient out to someone who can discuss whether or not that filter can be retrieved. And so, those would be the things that I think physicians should be asking themselves if those patients with IVC filters are not necessarily being followed by people who put the filters is to ask those questions and realize heh, it’s time to get this filter out, because it could cause problems for this patient in the future.
  
  Melanie:  Thank you so much Dr. Gunn, for being with us today and sharing your expertise in this pretty interesting topic. A community physician can refer a patient to UAB medicine by calling the MIST line at 1-800-UAB-MIST, that’s 1-800-822-6478. You’re listening to UAB MedCast. For more information on resources available at UAB Medicine, you can go to www.uabmedicine.org/physician, that’s www.uabmedicine.org/physician. This is Melanie Cole. Thanks so much for listening.
  
  
  
• Hosts:Melanie Cole, MS