In part two of an informative discussion, DocWire News partner Dr. Hady Lichaa continues his discussion with Dr. Matthew Bunte, a world-renowned expert on vascular and cardiac interventions. The topic at hand is deep venous arterialization (DVA), which is a technique that provides a limb-saving option for patients with chronic limb-threatening ischemia. In part one, Dr. Bunte broke down the technical nuances of the procedure. Here, Dr. Bunte details the clinical aspects of DVA procedures, recommendations he gives his patients post-DVA, what percentage of limbs are saved due to DVA, and much more.
Dr. Hady Lichaa: So now, getting out of the technical aspect to the kind of program development aspect, tell us how you started. Who are the players in your program? And how do you collaborate? And how do you…? Let’s start with that.
Dr. Matthew Bunte: Yeah. As a cardiologist, I have really come to appreciate how important it is to thinking about these patients almost like a transplant patient. I’m thinking about my heart failure colleagues and how there are many different clinical aspects to the case that lead you to offering these really complex solutions. But also, there’s that psychosocial dynamic, and this is really no different. I would say that, while this technique is very interesting and provides hope for a lot of patients, it is not without a significant team of registered vascular technologists, who know how to map the foot before the procedure and then, follow the graft flows after the procedure and do a good job with that, so you know when to go back in potentially to optimize the graft. That’s a key piece. Having a wound care provider that you’re close with, that can help manage these patients. Many of these patients get forefoot ischemia.
So having a great foot surgeon who knows how to preserve the pedal plantar loop and preserve those deep veins in the foot, but also, get rid of ischemic tissue or tissue that isn’t viable, that’s a really key piece. So you see it is really important to know how to do this procedure technically, but also, you have to be surrounded by folks. And I would submit, and I was on this study with a number of really world-class vascular surgeons. It is not a technique that can be done by a single person, because it really takes a village to take care of these folks. And I think all of us who do CLTI understand that concept. What is interesting about this technique, that I didn’t anticipate though, is just the amount of counseling that I now focus on before the procedure. So patients know what they’re getting into.
Patients can expect, if they have a gangrenous toe, for example, that, in a number of patients, that forefoot and toe may actually get worse before it starts to get better, that because of the way we’re providing blood flow to the midfoot, sometimes the forefoot gets pretty ischemic. If you think about it, we’re retrograde profusing the veins in the foot, those veins and some of the metatarsal veins also have valves. Those valves are oriented in the wrong direction as far as we’re concerned, because we want to provide flow to the forefoot. But those valves are such that they are bringing blood from the toes to the right heart. And so, they’re oriented the wrong direction. And so, sometimes, that can create a lot of forefoot ischemia, because the blood then rushes up the leg instead of providing flow to the forefoot. So that’s something we now counsel our patients on.
Patients who need a forefoot amputation, we learned, throughout the course of this study with PROMISE II, that, by primarily closing those wounds, they tend to get gangrene along the skin margins. So we’ve learned that we have to leave these wounds open to heal by secondary intent. And because many patients do require forefoot surgery for osteomyelitis or other reasons, it’s really important to understand the implications of going down this path of DVA. There’s no question that DVA works. It provides a lot of hope for patients. It does work to produce limb salvage, but it is not without a pretty significant involvement. And I think it’s just important for patients to know what they’re getting into and that they have the support around them to cross the finish line, three months down the line.
Dr. Hady Lichaa: Excellent. Dr. Bunte, it seems like the technical aspect of doing the procedure is probably the easiest part of the procedures, all the other aspects of the care and the collaboration, multi-specialty care. So from that perspective, do you all see patients in the same physical space with the foot surgeons, wound care specialists? Tell us about that.
Dr. Matthew Bunte: Yeah, a great question. It would be ideal to be able to be all co-located, but we are on the same campus. And I have really great colleagues that work with me, both in wound care, as well as orthopedic foot surgery, that have engaged and have helped me bring this treatment to patients who have no other option other than a major amputation. So I think it’s something that takes a village, and I think that’s probably reflective of many other practices around the United States is that a lot of folks aren’t necessarily co-located with their wound care center or podiatrists. But I think it’s just a matter of developing really solid relationships, and it’s a proper sequence of you’ve, first, got to counsel the patient, get them to the procedure, if they’re appropriate, and then, have a plan for that forefoot amputation, if it’s necessary, whether it’s for gangrene or ischemic toes after the deep vein materialization or transcatheter arterialization procedure. And that distal amputation has to be done to also preserve the midfoot arterial venous plexus and not disrupt your anastomosis you’ve just created the midfoot.
Dr. Hady Lichaa: And the other clinical aspect of this post-procedural care seems to be how comfortable docs and providers are with edema. So this is the central piece of, obviously, which defers completely from the reperfusion edema that we see sometimes when we revascularize [inaudible 00:05:49] and SFAs. So this is the aspect that makes a lot of people uncomfortable. Tell us, obviously, besides the usual edema, tell us about the recommendations that you have for patients post-DVA. And what are the alarming signs when you say, “No, this is just too much. We have to do something about it?”
Dr. Matthew Bunte: Yeah. So if you have patients who have very severe venous disease, advanced venous stasis ulcers, already, this may not be the procedure for them, because some folks do end up with more above the ankle venous stasis and venous leg lesions, if they’re really susceptible. We talk about that right upfront, and that’s part of the case selection for this procedure. It’s not to say that patients with vein disease, being as common as it is, is an exclusion, it’s not, but just to anticipate that. So if I were to bring a patient for deep vein arterialization, I’d really work to get the edema down before the procedure, have the patient understand that keeping the leg elevated, because once you put the graft in and once you make this artery to vein circuit, you can imagine you don’t want to compress the veins too much. Because then, you’re going to slow the circuit down and, potentially, close the graft.
So maintaining the flow through the graft is really important for patency. But yes, you can expect some swelling in the legs. I found it a little hard to predict how much swelling folks are going to have. It probably has a lot to do with the volume flow through the graft itself and through the circuit and then, what veins are carrying that blood flow back up the leg. But I will say, most patients who have this procedure, with proper counseling and kind of modification of swelling before the procedure, do pretty well. And most of that is just a low sodium diet, keeping the leg elevated. Walking is no problem with this procedure. And actually, that lateral plantar vein in the midfoot works as a pump, as you move the foot, and so, that just promotes circulation through the foot. So actually, maintaining activity, it’s a little tricky for some patients to also offload with the wound, but that’s no problem. So there are a few things we can do to mitigate swelling, and the swelling does tend to improve over time.
Dr. Hady Lichaa: Excellent. And from your review of the literature and your daily practice, these are patients who obviously would’ve gone all for an amputation, almost like a hundred percent, or end stage everything. What’s your experience in terms of limb salvage rate in this patient population? What’s the percentage of limbs that we are saving with deep venous arterialization? What’s the success rate?
Dr. Matthew Bunte: A great question. The ALPS registry was a registry done in Leipzig, Paris, Singapore, Alkmaar. There was a smaller registry of about 32 patients that they basically did a phase one first in human study of 32 patients on, and in that registry, over 24 months, with that initial experience, about 80% of patients had freedom from amputation in that two year timeframe.
Dr. Hady Lichaa: Wow.
Dr. Matthew Bunte: The LimFlow then sponsored the PROMISE I study, which was their kind of version 1.0 of their technology, and at six months, their freedom from amputation was 76%. And that’s pretty on par with what we’re seeing in this much larger experience with the PROMISE II study. And PROMISE II was obviously a much more diverse group of investigators, and it was a larger cohort of 105 patients enrolled in the study. And transcatheter arterialization, the deep veins was successfully performed in all but one patient, and 66% of those had six month amputation free survival.
Clearly, there was some advantage for patients who did not have end-stage renal disease with this procedure. The procedure worked significantly better for those folks. There were a number of patients, at that six months, about a quarter of patients, had complete healing, but that means everybody else was in kind of the process of healing, if they didn’t have any amputations. So it does take a while to heal after the procedure. So that’s, I think, where that counseling before the procedure really comes in is it’s a journey, but we definitely have a much higher success rate with this procedure than kind of continued wound care and other currently available options.
Dr. Hady Lichaa: This is a massive improvement in the care of patient. 80% limb salvage rate is unheard of in this Rutherford 6 population, and that has no options. And obviously, we know the effects of amputation on overall survival. Finally, I just wanted to ask you, so for endovascular specialists who want to learn this, who want to start getting involved, besides kind of watching this in professional society meetings, how are they going to learn this? And what’s your recommendation and practical advice?
Dr. Matthew Bunte: Yeah. Well, the good news with this procedure is, I think, LimFlow is making a portfolio of products that’s going to make the procedure pretty straightforward. And anybody who does routine chronic limb threatening ischemia intervention likely has skillset to do this procedure successfully. There are some technical aspects of it, that are a little foreign and new, like getting venous access in the middle of the bottom of the foot to step one. That’s something that most of us haven’t done before. I think, learning the venous anatomy, as complicated it as it is in a foot, to something to spend some time on, but then, building those relationships of the other peers that you’re going to need to engage, around getting the vascular testing done, the non-invasive vein mapping, and who’s going to follow those imaging studies afterwards help you to produce those images.
You got to work with an RVT that knows what they’re doing. And then, also, a wound care physician, who can help manage the wound, if you don’t do that primarily, and a foot surgeon, who understands some of the implications with needing to do a distal amputation, sometimes a guillotine or disarticulation amputation at the metatarsal heads, and then, not close that primarily. Because we know that’s not a very viable option for this procedure. Those are the things that I would say folks should start working on now. LimFlow is really eager to get this approved by the FDA, and that is in process. And I think that will happen, but then, just, I think, opportunities like this to talk about the procedure, see it in action, the support we’ve had from LimFlow has really been incredible.
They’ve got a great group of folks who are really well experienced in the cath lab and can walk you through this procedure. This is something that there’s probably going to be opportunities to have folks proctor cases or see live cases, and I think probably having that support group around you to have success for this is probably the most important point I’d like to make. And that’s something you can get started on now.
Dr. Hady Lichaa: I can easily imagine you traveling around the country and meeting a lot of folks and sharing your experience, so I’ll end our discussion on the time investment aspect of the procedure. Obviously, this is laborious. This is not a quick in and out. So talk to us about, for people who are planning on possibly doing this in the future, talk to us about this aspect of a busy outpatient endovascular practice and what they’re expecting from.
Dr. Matthew Bunte: Yeah, I think this really speaks to just CLTI in general. To do CLTI really, really well, you definitely have to go the extra mile, and these are not easy procedures in general, let alone these transcatheter arterialization procedures. But these patients need hope, and they need a doc who cares about them, who knows how to deliver great medical care as well, and can counsel them through their other comorbidities that they may have or know how to resource somebody to get them the help they need. Really, this is a journey for patients, that takes about three months to get them to a point where they’ve saved their limb. And in that time, it does take a lot of extra effort on our part as physicians to look out for our patients, to make sure that we’re not just doing a procedure and then, sending them off.
This really is a procedure that you have to own, if you’re going to expect good results. But when you do, man, it is satisfying, and it is great for patients. And it keeps you coming back. We all have those experiences, where, in the thick of it, it’s really tough and it’s really hard work that we do, but when you get a patient across the finish line, it’s nothing better than that.
Dr. Hady Lichaa: That’s an awesome note to finish. That was a great pleasure. We really appreciate all the information you gave us today, and thank you for your commitment and for the limb salvage mission that you have.
Dr. Matthew Bunte: Yeah, absolutely, and I really appreciate the opportunity to chat today. It was a lot of fun.