Section: CME Category: Vascular

Treatment of PAD - Techniques and Goals

Charles Andersen, MD

Charles Anderson, MD discusses various treatment options for peripheral arterial disease and alternatives for those candidates for which revascularization is not possible.

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Goals and Objectives
  1. Describe the pros and cons of open surgery for establishing perfusion to the lower extremity
  2. List endovascular options to establish perfusion to the ischemic extremity
  3. List the goals in revascularization of an ischemic extremity
  4. Describe options available to improve perfusion if revascularization is not possible.
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  • CPME (Credits: 0.75)

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    Release Date: 04/12/2018 Expiration Date: 12/31/2020

  • Author
  • Charles Andersen, MD

    Chief of Vascular-Endovascular-Limb Preservation Service and Medical Director of the Wound Care Clinic at Madigan Army Medical Center
    Tacoma, Washington
    Clinical Professor of Surgery at the University of Washington and the Uniformed Services University of Health Sciences

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    Charles Andersen has disclosed that he is a consultant/advisor for KCI, Organogenesis and Stryker.

  • Lecture Transcript
  • TAPE STARTS – [00:00]


    Speaker: Now I move from the identification of vascular disease to the treatment of vascular disease. Again, no disclosure on the same person, same biases. The learning objectives we are going to discuss the pros and cons of open surgery versus endovascular procedures for improving perfusion. Discussed the various endovascular options to find the goals when we are thinking of revascularization and discuss the options available to improve perfusion if there is no revascularization that can be performed. The big picture again working together that timely diagnosis and early treatment if treatment is required. So one of the factors that was very interesting paper a number of years ago where they look back in retrospect -- this was out of Denver -- they looked back in retrospect of patients that ended up with a major amputation despite the fact that they have very active lymph preservation program. And what they found was delay in referral or delay in treatment of coexisting vascular disease. So if you identify somebody with an ischemic toe or wound that's not healing and you wait for two months or a month even to get a vascular evaluation and appropriate treatment, unfortunately, that patient may progress significantly during that period of time when you are waiting for intervention. So timely diagnosis, timely treatment when treatment is indicated.

    [02:01]

    So some very key questions when you are talking about the treatment of PAD -- does the patient have arterial disease? We have already talked about the modalities that you can use to diagnose the arterial disease. If they have arterial disease, do they require revascularization? When should the revascularization be done timely? I mentioned that you can get into trouble with delay. And what treatment options should be utilized? Endovascular procedures, open surgery, hybrid procedures that means that on open vascular procedure, it's combined with an endovascular procedure in order to establish perfusion. How far distal if you're-re-vascularizing, you have to go all the way down to the foot, can you just treat in-flow disease? We talked about treatment, so treatment oftentimes if you hear somebody say how are you going to treat vascular disease immediately, people start talking about surgery or endovascular. Key is everybody with vascular disease should be undergoing medical therapy for their atherosclerosis even if they are going to have a procedure to have that antiplatelet agent onboard to have their hypertension controlled to control the risk factors, in particular smoking, then you will get better outcomes from your intervention whether it's an open intervention or whether it's an endovascular intervention. Certainly, not all patients with PAD require surgical treatment.

    [04:00]

    The natural history of claudication is actually very benign. So when those patients come with claudication and they say, I can only walk two blocks, those patients initially are managed medically or non-operatively and they are placed on an exercise program. The risk factors are modified and many times the claudication can improve and only in a small percentage of those patients will continue to progress to limb threatening ischemia. The indications for operating on patients with claudication then are lifestyle limiting claudication. If somebody says my job requires me to walk, I can't walk, I can't work. Then that's an indication to intervene in claudication and certainly limb threatening ischemia. So the natural history I mentioned is fairly benign. If you look at five years, only 7% of patients with claudication progressed to limb-threatening ischemia. That's a very old study by Dr. Boyd, but that study has been repeated many times by Dr. Garland and Dr. Cronin Root [phonetic] and very similar results that if claudication is just followed, the majority of those patients do not progress to limb threatening ischemia. So the mistake when you first learned about vascular disease in school or earlier in your practice, the assumption is that somebody has vascular disease, you better treat it early before they develop limb-threatening ischemia. There are some pitfalls to that. They should be treated medically but not necessarily with a procedure unless they have lifestyle-limiting claudication.

    [06:02]

    The goal in treating claudication should then be long-term patency and endovascular treatments for infrainguinal disease in general are not especially when you get below the knee. When you are doing an endovascular procedure, the problem as you may get early relief of symptoms but that if that disease recurs as oftentimes it does with an endovascular procedure, those patients when the procedure goes down or when they develop recurrent stenosis, unfortunately those patients many times are not claudicated anymore. They are now in the category of limb-threatening ischemia. So early interventions, especially with endovascular intervention, you have the potential to change the natural history of that disease, so instead of having the patient that has 5%, 10% rate of progression at 5 or 10 years, if you do a procedure and that procedure goes down, then oftentimes you have changed the natural history and the disease becomes more severe and they require additional intervention. So the key is that endovascular treatment of claudication does not prevent limb-threatening ischemia. That's a critical statement. Just because you treat the patient early, especially with endovascular surgery does not mean that you have not prevented limb-threatening ischemia. So you have to be very careful with your indications for treatment of vascular disease early. Lifestyle-limiting claudication, yes; the wound that wouldn't heal with associated vascular disease, yes; or critical limb ischemia with rest pain and especially with a wound, absolutely yes.

    [08:05]

    So big picture again, timely diagnosis wean options for treatment and especially if you are dealing with a diabetic patient that has a wound that marriage between vascular surgery and podiatric surgery, critical ischemia can be treated. There are still a large number of patients that when they are diabetic, the assumption is they have small vessel disease, that it can't be treated and therefore there are many amputations still performed in this country with patients with diabetes that have wounds, they do not even get an arteriogram. The assumption is that they are not a candidate for intervention and they end up with an amputation. That's wrong. And we will talk tomorrow about amputations but we should try to avoid an amputation if possible in the majority of patients and certainly the identification of vascular disease and we now have options to treat the majority of PAD. So don't blame ischemia on small vessel disease. When should the patient be revascularized? So if you have critical limb ischemia, so you have a patient that presents with rest pain. So they come to your office and as they say I have pain across my metatarsal heads. When I put my foot down, the pain goes away. You see that patient in clinic they have dependent rubor, pallor on elevation and you do non-invasive studies and they have significant vascular disease. There is a window of opportunity there before they develop a wound.

    [10:04]

    That's critical because if you identify them before they have a wound, often time the amount of revascularization that's required is less than if they have a wound. So somebody with critical limb ischemia that has multilevel disease, so if they have aortoiliac disease, superficial femoral disease and distal tibial disease, if you treat when they have only ischemic rest pain, no wounds and oftentimes you can just augment inflow. So you can treat the aortoiliac disease, sometimes treat the superficial femoral disease but you rarely have to go below the knee if they don't have a wound. That same patient if you ignore this or it's ignored in our medical system and they then progress on to a wound, then it requires more extensive revascularization in order to get that wound healed. So critical limb ischemia prior to tissue break down, wound associated with critical limb ischemia and acute infection associated with arterial insufficiency. This is a question that often comes up on our rounds. You have somebody that comes in. They have an infected diabetic foot. We heard a couple of very excellent lectures yesterday on treatment of infected diabetic feet. If they have associated vascular disease, that should be identified but the infection drain first. With the removal of infected tissue, the drainage of any purulence. Then once that's dealt with not definitively but certain any undrained pus, any resection of necrotic tissue, the patient stabilized on antibiotics, then they can re-vascularized and then you can look to the definitive procedure.

    [12:12]

    So limb-threatening ischemia. Patients with limb threatening ischemia oftentimes have, as I mentioned, associated coronary artery disease. As a result of that, those patients are at higher risk for a major revascularization. So a distal bypass, which is an excellent operation, is a significant physiologic insult and oftentimes can create significant wounds just from the procedure, and unfortunately, sometimes of those wounds don't heal appropriately and sometimes those patients have perioperative morbidity associated with coronary artery disease. So this has led to the endovascular first philosophy in many centers for those patients that have significant generalized atherosclerosis and present with limb-threatening ischemia. The goal in those patients is obviously to treat ischemic rest pain and heel wounds. Even short-term patency can be important. Again, going back to the fact that it takes this amount of blood to maintain intact skin, this amount of blood supply to heal the wound. If you have a wound that the patient is revascularized, the wound is healed even if there is some recurrence of that vascular disease as long as you don't get another wound, many times those patients are out of trouble and don't necessarily require reoperation. So short-term patency in those patients to get a wound healed oftentimes is very, very helpful.

    [14:09]

    When should a podiatric procedure be performed following revascularization? This is a question that oftentimes comes up and again that marriage with vascular intervention and podiatric surgery. So you have a patient that has some ischemic toes, they have significant vascular disease, ultimately let's just say for discussion sake that they are going to require a TMA. So you do a revascularization procedure. When should the TMA be performed? Unless there is a need to do an emergent procedure because of infection or conversion to wet gangrene, it's best to wait at least three or four days and sometimes even longer after the revascularization prior to the podiatric surgery. Early studies by Dr. Sumtner and Straners [phonetic] again just put a simple ABI demonstrated after you do revascularization, oftentimes in the first two or three days, you will see continued improvement of that ABI. Those of you that have seen or been involved in significant vascular intervention, when those patients get to the recovery room, you may have a signal present but not a great signal but later in the evening that signal is improved. By the next day, the signal is even better. So in general, we don’t combine podiatric surgery with vascular surgery at the same setting. We allow the benefits of the revascularization prior to performing the elective podiatric procedure. So what do we do, how far that we do it? As I mentioned, endovascular philosophy, endovascular first philosophy is something that is now very common.

    [16:05]

    Open surgical procedures may have better long-term patency and in certain patients that's still a better option. So endovascular, I call it a revolution. I am old enough that in my career I have seen vascular surgery completely changed from a surgical specialty where we did aortofemoral bypasses, endarterectomies, femoropopliteal bypasses, femorotibial bypasses, femoral-femoral bypasses, all kinds of open surgery to now the majority of the cases are treated from within the artery. So instead of an incision and some kind of an open vascular procedure, the majority of time now the vascular disease is treated from inside the artery and that's called endovascular surgery or endovascular procedures. So that field is very, very rapidly evolved. The training, the skills, the endovascular interventions have continued to improve and the tools have continued to improve. If you look historically in the last 10 to 15 years, there has been three-fold increase in the endovascular procedures and bypass procedures have decreased by 40%. I would say if you looked at that today, it would be even more profound that endovascular procedures are certainly done much more commonly and in the majority of patients versus an open bypass procedure. So better tools, better training, better skills and also the ability to do those procedures not only from an antegrade approach coming from the femoral artery going up what we call an over down the other leg and treating from above but if you can't get through a total occlusion.

    [18:24]

    For example coming from below, getting access in the foot, coming from below meeting in the middle and being able to treat the disease. So even it was mentioned yesterday by Dr. Freiburg that in his travels in Europe, he had some very, very aggressive endovascular specialists that even are accessing vessels in the toes with very, very small wires and then going from below up and reestablishing patency not just to the ankle but also doing interventions within the foot in the arch of foot. So many of these skills were taken from the cardiologist and there are cardiologists that do endovascular procedures and some of them are very, very good. So depending on where you are practicing, you want to have the ability to evaluate and treat vascular disease that may be a vascular surgeon, that may be an interventional radiologist but at times it's also a cardiologist that have those skills to be able to reestablish flow to the foot. An angioplasty just means that in an area where there is now a residual stenosis either because that's what was there initially or you have done a procedure that now you are left with a stenosis and angioplasty, just a balloon is used to stretch out that artery.

    [20:08]

    It's actually a controlled injury of the artery. It splits the artery and pushes that plaque away and that establishes better patency. Oftentimes, an angioplasty is used alone in a larger vessel, many times associated with a stent. So the stenosis is treated with a balloon and then a stent is placed to hold that artery open and help prevent recoil or restenosis. But a plain angioplasty depending on the location is going to be better in larger vessels. As you go down towards the foot, the results aren't going to be as good. Cryoplasty, it's a technique where a cold balloon is utilized for the angioplasty with a goal of preventing restenosis or decreasing the instant of restenosis. A cutting balloon, if you have oftentimes a recurrent stenosis, very fibrotic, then a cutting balloon can cut that area of stenosis and then it's dilated with an angioplasty and then a stent is placed. So these are just additional tools that are now available to the vascular specialist. Stents have continued to improve. Nitinol is a material that was actually developed in the military. It's a material that has a certain shape when it's cold. When it's then exposed to room temperature, the stent expands.

    [22:03]

    So when it's placed in the blood stream, the stent expands to the size of the blood vessel. So it's self-expanding stent. The stents have also become very, very malleable. So for example if you are placing the stent in the distal superficial femoral artery around the knee where there is a lot of movement in that stent, then the newer stents can withhold that movement without fracturing the stent or without developing instant stenosis. So Nitinol stents improve stents -- here, you can see what happens in the distal superficial femoral artery. With flexion of the knee, those stents have to be able to tolerate that stress. So improved Nitinol stents have all become part of the tools. As stents have improved, patency has improved and then additional things have been added to stents so that now there are coated stents and the idea with coated stents is to decrease the incidents of restenosis within that stent. There are now coated balloons, which again the goal is to prevent restenosis within that area where you have treated the vascular disease. Here, you can see again how those stents have to withhold or withstand flexion of the knee and you can see what occurs in that distal superficial femoral as the knee is bent. So the coating is what's called drug-eluting stents or drug-eluting balloons and again the concept is that it helps prevent restenosis in those areas that have been treated.

    [24:12]

    In addition to that, stents now can be covered stents. So you have the benefits of Nitinol stents but then you can put PTFE or sometimes people know it by Gore-Tex that can cover the stent so that that can be very useful. For example, we know use that in trauma. If you have a hole in an artery, instead of going in and doing an open repair of hole in an artery, even in theatre, even in Iraq, covered stents are placed over a hole in the artery and that then reestablish its flow, but prevents egress from that hole in the artery. So covered stents and now the addition of heparin to those covered stents, again another addition to help decrease the incidents of instant thrombosis and the drug-eluting technology to help decrease the incident of intimal hyperplasia, which is what generally leads to stent failure or stent stenosis. So the Viabil on stent graft again is a covered stent graft with very, very good patency, for example, in the superficial femoral artery. Sometimes you have disease that it's difficult to get through that disease and that's where you get into lasers that can be an adjunct to get through an area of total occlusion, reestablish some degree of patency and then you can do the balloon angioplasty and stenting.

    [26:04]

    So lasers again can play a role in select patients. It used to be that total occlusion, so not a stenosis but now the artery is totally occluded. Early in endovascular therapy, that was contraindication to endovascular therapy. So if you had what's referred to as a task D lesion, that’s a classification of lesions and you had a total occlusion, then the patient required bypass. Now with lasers and with re-entry devices, you can get around an area of total occlusion, reestablish a lumen and then treat that. So re-entry catheters have become very, very important. Atherectomy is again another way to treat disease where you want to decrease the disease burden prior to placing a stent. Atherectomy catheters have been various types that have been available, laser atherectomy or rotational atherectomy. The goal is to remove that disease and then proceed on with treatment of the residual stenosis. So a chronic total occlusion is no longer a contraindication to endovascular procedures. And the re-entry catheters, that means when you get to the level where there is a total occlusion, if you can't get through the total occlusion, you go around the total occlusion, so you actually create a plane within the wall of the artery or create a channel within the wall of the artery and then you stent that open. So you are creating another lumen around the occluded lumen.

    [28:04]

    So here, you see a total occlusion, re-entry catheter and this is what I mean by you enter around the plaque, create another lumen and then that lumen is stented open, so you can now treat total occlusion. Open surgical bypass is still a very, very good procedure. Very high limb salvage rates there. There are still centers in the United States where that's commonly performed and they have a lot of expertise. The down side of that is these patients oftentimes have significant coronary artery disease as I mentioned and you can have perioperative complications from a cardiac standpoint or end up with wound complications because these patients start with limitations in their ability to heal a wound or a long incision. Open surgical bypass has much better long-term patency and you are able to get direct flow to the area of ischemia if you can find a target, so a very good limb salvage rate. Open surgical procedures restore pulsatile flow to the area where you have the target vessel and if you have pulsatile flow to the area or the angiosome where the ulcer is located, then high chance that you can get that area to heal. With endovascular procedures oftentimes, that's what called an indirect revascularization, you may not have total patency all the way to that angiosome, so it's more an indirect revascularization.

    [30:09]

    So how far distal? It really depends on what you are treating. The bigger the wound, the more blood is required to heal that wound. If you have a small wound, sometimes you can augment vascular supply and get a wound to heal. If you have significant ischemia with a very large wound, the ideal is to establish what is called in-line flow, so that's direct patency all the way to the level of the ulceration or the wound and then you are going to get better healing ability. So that's in-line flow. I mentioned if you are treating the patient early before they have a wound, many times you can just augment inflow and you don't have to establish in-line flow all the way to the foot. So direct versus indirect. Direct is if you can get in-line flow directed to the area of the ulceration or the wound. Indirect, you're still dependent on collateral flow to get that flow to the wound. So you have augmented the inflow but there is not a direct channel all the way to that wound. So the angiosome, that's the area of the foot where the wound is located and there is data to support that if you can get direct in-line flow to the involved angiosome that you will have better healing. This was a meta-analysis of papers that deal with that question. Angiosome targeted lower limb revascularization and again support of the concept that the ideal is to get direct in-line flow to that angiosome or area of the foot that the artery is supplying that area of the foot in order to get better healing of the ulcer or that wound.

    [32:21]

    It's very important to understand regional perfusion to the foot. I mentioned in the first lecture when we were talking about ABIs that ABIs measure pressure at the ankle and not pressure at the foot. So you can have a normal ABI. You can have even normal toe pressures and have regional ischemia to the foot. That's very true in a heel ulcer. The blood supply to the heel is kind of watershed area. So you have some distribution of flow from the peroneal or the posterior tibial. You can have disease within the foot and you can have ischemia to the heel and that will not be picked up by standard non-invasive vascular studies. So when you are doing an arteriogram in a patient that has a non-healing wound, the goal is to get good visualization of those arteries down to and including the vessels in the foot. So you can identify ischemia within the foot. You can say why? Oftentimes with newer techniques, you can actually get down into the foot even to the arch of the foot to re-establish regional flow and you can certainly see where the collateral flow is coming to the regional area of ischemia and augment collateral flow to that area.

    [34:07]

    A good example of regional mild perfusion. Here, you see pretty normal-looking vessel at the ankle, so the ABI may be normal but you see that vessel basically ends in the foot. Again, an area of regional mild perfusion. This can be very, very important, for example if you are doing TMA, you can end up with flap problems if you don't realize where the collateral flow is coming to your posterior flap or to the anterior skin. So important to understand and map regional perfusion in the foot. So which do you do endovascular versus bypass? The study that's generally quoted is the BASIL trial. That actually showed similar early results with endovascular versus open, so was earlier used to support endovascular. Longer term results actually supported the benefit of bypass surgery. So certainly in patients we talked about the difference between claudication, the difference between those patients that have a wound and don't have a wound, if you are looking at long-term survival, there is a benefit to bypass versus endovascular procedures. What about patients that despite all of our tools, we don't really have the ability to revascularize those patients? That does not mean that those patients need to go on to an amputation. We now have tools that can treat ischemia even in the patients that don't have a target for bypass.

    [36:04]

    Timing is critical. We have talked about this. Again, no wound treated early before the wound progresses. So timing really is critical. What happens after we do the procedure is very, very important that these patients are monitored because the chance of recurrence so that recurrent disease needs to be identified. We meet the vascular, podiatric and the wound care meets together as a team. We call that our huddle and for example if the patient has had a revascularization, the wound was progressing and now all of a sudden that wound has stalled, that may mean restenosis, that patient needs to be restudied with at least an ABI, toe pressure or Duplex and may require re-intervention to re-establish flow to get that wound healed. So monitoring both clinically and with Duplex scan in those patients that have had procedure to identify early recurrent disease. And if early recurrent stenosis is treated before total occlusion occurs, the long-term patency goes back to the baseline from the primary procedure. So I mentioned there are options available. If you have non-reconstructible disease, we have had a fair amount of experience with the Ardisist [phonetic]. We previously had a poster at this meeting and now have a paper in publication in the journal wounds.

    [38:03]

    That shows that with the Ardisist [phonetic], you can increase skin perfusion and in patients with wounds, some you can get those wounds to heal, not every time, but don't give up on a patient even if they can't be revascularized. This is another option. This was on our initial poster, as I mentioned, the publication is pending. In our institution, we used fluorescent angiography as a modality to look at skin perfusion and we have been able to demonstrate in patients that we have used the Ardisist [phonetic] in that actually patients can increase skin perfusion and lead to healing of the wounds. It can also have some long-term benefits on patients with claudication. So in conclusion for our second talk, revascularization is a key component of limb salvage. Decision about what, when and why are as critical as the technique. Now, the question is oftentimes not can you do it, the question is should you do it. So we have the ability to go all the way to the foot in the foot, but when should that be done. So it's not can you do it, when should you do it and what should you do and the timing of what of what you do.

    TAPE ENDS - [39:32]