Board Review Vascular

Bypassing the Obstruction - an Open Highway

Cameron Akbari, MD, MBA

Cameron Akbari, MD, MBA discusses surgical options available to treat atherosclerosis in the ischemic patient. Dr Akbari discusses and compares open revascularization and endovascular bypass techniques. Atherosclerosis in the diabetic patient is presented in detail. Images of angiograms and intra-operative procedures are included.

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Goals and Objectives
  1. Review the multiple open bypass options available to treat lower extremity ischemia and their 5 year patency rates.
  2. To discuss the importance of revascularization in an ischemic, diabetic patient.
  3. Understand quality of life gains obtained by successful revascularization.
  4. Review endovascular techniques and how they compare to open bypass revascularization.
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  • CPME (Credits: 0.5)

    PRESENT eLearning Systems, LLC is approved by the Council on Podiatric Medical Education as a provider of continuing education in podiatric medicine.

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    Release Date: 03/16/2018 Expiration Date: 12/31/2018

  • Author
  • Cameron Akbari, MD, MBA

    Washington Hospital Center
    Washington, DC

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  • Lecture Transcript
  • I am going to be spending a few minutes talking about treating critical limb ischemia, treating the arterial occlusion and this is quite a large topic, quite a lot to cover, it's a pretty big highway, so we will try to get through it as much as we can. I have no financial disclosures, the principles of limb salvage in those patients presenting with Rutherford five, six critical peripheral arterial disease that is with tissue losses something we all know, but to reiterate that first control the infection, drainage, drainage, drainage, antibiotics, at the time of the evaluation for ischemia the idea being that we want to restore maximum profusion to the foot ones the infection is under control which usually is no more than three to five days. And then finally secondary foot procedures can be performed in the fully revascularized foot.

    The principle behind ischemia and the diabetic foot are fairly simple. The diabetic foot is biologically compromised, we heard some of that just now and so far as some microvascular dysfunction, we’ll talk a little bit about that more. So even in a moderate degree of ischemia in this altered biological milieu will lead to ulceration and prevent healing, what we want to do is improve healing with the correction of even that moderate degree of ischemia. And really bear in mind this is perhaps the most important statement here that the biologically compromised foot necessitates maximum circulation to heal the ulcer.

    This is a, I think a very important slide to recognize, which really puts that profusion, neuropathy compromised, biology access all together here. So you can see that in those patients who have completely normal arterial circulation with increasing levels of neuropathy, they will not ulcerate, but ultimately even at near perfect arterial profusion with increasing neuropathy they will ulcerate. So that a patient who has say 80% profusion, but significantly increased neuropathy and compromised biology falls right in here, ulceration and you can see that it starts not at 0% but even higher. So that it's a biologically compromised foot and the rules of arterial profusion do not apply we need maximum profusion; we want to be up here so that we are over here.

    Again many of these were reiterated in the last talk but we everyday see this in our office, the patient with no ulceration with a classic diabetic foot and in this very benign looking foot all of these things are going on. Microvascular dysfunction which Dr. Anderson very nicely talked about, vasomotor dysfunction of the AV shunting, basement membrane thickening, glycosylation of the matrix proteins, loss of the sweat glands which leads the dry callus skin leading to fissure and ulceration, the diminished sensation, the sensory motor neuropathy and finally arterial ischemia due to tibial peroneal disease all of this stuff right in here. I don’t need to tell you by now that this represents an altered biological milieu.

    So when we do perform revascularization how do we decide, well the idea is to restore maximum profusion of the foot. And so our first choice is that vessel which is going to give us maximum flow that is to restore a pulse to the foot. Often times with open revascularization were limited in what we can do based on the availability of autogenous conduit, the idea being that conduit, good quality conduit is the key to this operation. So we perform revascularization with alternate targeted inflow arteries and in the absence of tissue loss other strategies for revascularization maybe considered. So that if somebody with rest pain may not necessarily need pulse to top flow, all we want to do is alleviate the rest pain and contrast the diabetic foot ulceration in which we do want to restore maximum blood flow.

    The cause of ischemia is the same in the diabetic and non-diabetic plain old generic atherosclerosis, not small vascular disease, good old blockages, atherosclerosis the only difference is in the pattern or location of the disease and this is what we are talking about, multiple studies, anatomic studies have shown that the classic diabetic pattern of vascular disease is the in foot geniculate vessels that is the tibial peroneal vessels, but the arteries in the foot are spared and this is what allows for the dorsalis pedis bypass, the paramalleolar bypasses which many, many publications have attested to the success of that operation and we see that every day.

    This is a very old arterial VAMP dating back to the 1970’s again showing that classic pattern where the vessels to the knee are widely patent, but there is extensive tibial disease present but reconstitution of the dorsalis pedis artery is seen here and again another example more recently widely patent femoral popliteal arteries but with disease effecting the trifurcation of the tibial vessels both reconstitution of a dorsalis pedis artery and this is of course yet another cartoon, which illustrates that again, patent vessels in the foot allowing for bypass to these vessels. No small vascular disease here and tibial peroneal occlusive disease and this is what allows for this, an example of a popliteal to dorsalis pedis artery graft seen here, here is the bypass to the dorsalis pedis and of course that foot can then go on to heal.

    Other patterns do exist; don’t think that all diabetics are going to have this classic pattern. In those patients who smoke you will also see concomitant femoral popliteal disease or isolated femoral popliteal disease, these are the patient in home we may do some sort of intervention such as a Fem-Pop bypass, one SFA angioplasty, other smokers may have aortoiliac disease and they need a more proximal intervention. So even though we recognize the classic anatomic pattern in the diabetic other patterns do exist. But ultimately the choice of revascularization is dictated by the location and the extent of the disease combined with patient specific risk factors and I will talk about this a bit more.

    So open bypass for tissue loss it's a great operation it's the gold standard, there is hundreds of reports out there which attest to that, there is excellence patency from some centers, some centers really do it right, they can be done well in multiple patient populations and the success of most of these reports is measured in terms of patency and then salvage and there are some implications with that as we will see. The general principles you need inflow that is the source for your bypass graft, that is the inflow artery, you need conduit to carry the blood and you need the recipient artery which is the outflow.

    A variety of operation can be performed for inflow operations that is restoring flow to the inguinal ligament, aortobifemoral bypass, iliofemoral, femoral-femoral and access of femoral bypass are just some of the ones that we are talking about. Here is a cartoon illustrating aortobifemoral bypass; the aorta is exposed through an abdominal incision as well as bilateral groin incision to expose the femoral arteries. The aorta ones is exposed retroperitoneal is typically freed up for its segment. The femoral arteries seen here are also dissected free and then a bypass graft is taken either end to end to the aorta or end to side to aorta really no difference ultimate at the end of the day and then anastomosis to the femoral arteries as seen here. This is again the example of the different types of the aortic anastomosis which can be performed and the femoral anastomosis is done in a usual end to side fashion seen here.

    In some patients they can’t tolerate such a big operation and so we will contemplate doing something called an axillobifemoral bypass in which the auxiliary arteries serves as an inflow source and this illustrates that here again a long graft is taken from the auxiliary artery down sown to the femoral arteries and this is combined then with a fem-fem graft to increase the outflow of the auxiliary bypass and the operation can usually be done with minimal morbidity again in high risk patients. Aortobifemoral bypass is an excellent operation, it really is the standard for the inflow operation and 90% plus five year patency even in axillobifemoral bypass in some patients can have quite impressive patencies so really these inflow operations in general yield very good results, aortobifemoral in 90%, 85, 85% for iliofemoral, even a fem-fen when axillobifemoral very good results.

    For lower extremity bypass that is for those bypasses below the inguinal ligament a variety of options exist, this is how we, this is how we classified those types of grafts, it can be done as a reversed vein graft, it can be done as a nonreversed translocated vein graft that is the valves are cut but the vein graft is then translocated. The vein can be left in its bed and the valve is cut and so called in situ vein graft. When we don’t have vein we utilize a prosthetic and then very rarely we will use these composite prosthetic vein grafts in isolated circumstances. The general principles autogenous grafts are preferred over prosthetic high quality conduit is the key to success through the superior patency of greater saphenous vein grafts but there is more and more data suggesting that prosthetic grafts combined with adjuncts may provide comparable patency and I will show you a few examples of that.

    This is a cartoon illustrating the in situ bypass in which the vein is exposed that it is divided at the femoral vein, the saphenofemoral junction and the first valve is cut at the saphenous vein and then subsequently all the other valves are cut, this is an example of the Mills Valvulotome remember the vein is not being flipped. This is something which I do routinely angioscopy and this is what the vein looks like with the scope again this is the valve here, the Valvulotome is cutting the valve and that’s what it looks like there. The anastomosis are performed and in terms of your life typically the femoral vessels are exposed first, the vein is exposed, this is an example of a femoral tibial bypass that I did, this is the great saphenous vein here, I paid meticulous attention to the skin flaps here, you can see the flaps are equal and certainly in my experience there has been no problems with wound healing as long as you take meticulous care with opening and closing even in a floppy leg like this, as long as you are meticulous about not creating flaps and as long as you are meticulous about the closure and don’t relegate that to the hands of an internal resonant you can have excellent results.

    This is the proximal anastomosis seen here and you can see this is going to be a translocated vein graft this is I have tunneled it deep to the sartorius muscle with this red rubber catheter so ones this anastomosis is performed this graft will be placed into this tunnel and here is a close up of the femoral anastomosis and here is an extreme close up of the tibial anastomosis seen here and again going deep to the tissues and an excellent operation. Again another example of somebody who had a failed TMA and multiple attempts; multiple, multiple attempts you can see all the debridement’s, debridement’s further amps, further amps, all sorts of things, a dorsalis pedis bypass really just saved the day and you can see here the healed pedal incision and the healed proximal TMA.

    Again as we lack outflow, as we lack conduit, the complexity of the operation increases. Certainly the thing that we face most often is this, we don’t have good quality greater saphenous vein conduit in those examples we use a prosthetic graft and we combine that with an adjunct and there is more and more data suggesting that these operations do work to the tibial vessels, this is an example of that you can see here the tibial vessel here, we use a vein patch directly on the tibial artery and then sow the prosthetic graft on to the vein patch as seen here and the results really are quite impressive.

    Thromboendarterectomy maybe done in certain high risk patients for isolated common femoral than external iliac artery disease, here is an example of that. This patient has significant disease at the inguinal ligament. Ones the femoral vessels are exposed the standard endarterectomy is done here, you can see here the artery is opened, the plaque is beginning to be removed from the artery, again the forceps are grabbing now the arterial wall after the plaque has been removed. More of the plaque being removed here, here is the plaque being lifted up, held with a forceps and the plaque is removed and this is now the cleaned out artery, beautiful, beautiful segment of artery here and looking down at the profunda and the superficial femoral artery and then it's closed up with a patch and here is the completed patch here and a close up of that.

    So overall open bypass for tissue loss we saw this slide before it's an excellent operation it can be done well, there is excellent patency, the success is measured in terms of limb salvage and patency, these are the quoted five year rates this is what we all memorizes medical students well a fem-pop bypass is a seventy to 80% five year patency, even tibial bypass is about a 60% five year patency, overall fifty to 70%, this is the classic coded five year patency. Well the results from the largest randomized prospective blinded trial was the core genetic Prevent III Trial, fourteen hundred patients were randomized to receive a drug to prevent into more hyperplasia and so those patients were all meticulously followed and all these patients received autogenous conduit, vein as a conduit.

    High risk conduit that is an alternate conduit such as an arm vein and 24% and 65% of these with the tibial and you can see here real life data one year patency, at one year 20% of the patients were dead, 30% of the grafts were no longer working. So again the real life data perhaps are a little bit different from those quoted data. In addition to which we are starting to realize that there is more and more recovery needed after this operation that patient has the entire leg flayed open it's going to take some time for them to recover from that.

    So although we know all of these things here, this is the question we have to ask, how long before that patient gets back. Well we know these are some general principles that typically takes at least three to six months for healing of the foot, there is tremendous variation between reports and so far as mortality and morbidity. Most patients return to their preoperative status that is a non-ambulatory patient will remain non-ambulatory. Unfortunately only 40 to 50 % of patients report really being back to normal at six months, 25% of patients who were independent preoperatively are no longer independent postoperatively; only 75% of patients remain independent after a bypass. Better function before bypass is associated better function after bypass so an 80-year-old marginally functional, marginal ambulatory patient who undergoes an extensive bypass is more likely to fall into that fifteen to 25% group that becomes, that losses their independence and certainly what we want to avoid is this, limb amputation because that has the lowest quality of life scores. All this is derived from about I don’t know fifteen to twenty combined reports looking at quality of life scores and [indiscernible] [00:17:13] bypass.

    So another alternative exist that is endovascular interventions and there is a changing paradigm, it really does provide immediately symptom relief, an excellent immediate success and there are some encouraging data to support it as well. A whole lot of options are out there from plain old balloon angioplasty to stenting, I am sure many of you have vascular surgeons at your institutions and you hear some of these terms all the time. Drug alluding stents, drug alluding balloons, cryoplasty, atherectomy and so forth; there is more options that ever in our endovascular armamentarium.

    Here is an example of a classic endovascular, suitable endovascular lesion, patent femoral, superficial femoral artery with a distal superficial femoral artery and above knee popliteal artery. Occlusion about a fifteen centimeter occlusion seen here and after endovascular treatment, after angioplasty and stenting there is the final result widely patent and you should expect very good outcome for this patient. This is more significant disease seen here and again the final shot seen there. This is the classic patient whom we should consider for endovascular intervention, a severe, severely ill patient with critical limb ischemia, ischemic rest pain, ABI of zero; renal insufficiency had an MI six weeks ago and has very bad cardiomyopathy. Well, obviously an amputation maybe considered but at the same time if we can offer something in the form of percutaneous treatment why not do that and this is a -- and when I saw him I really felt quite bad for him. He had been in the hospital for a couple of days with this but prior to that was that your living at home recovering from his MI was getting along, was living with his pain which got worse and you can see here it looks pretty dismal, it really looks quite dismal, no profunda, no common femoral, a wisp of a popliteal seen here and a variety of wires and so forth and here is his final result seen here.

    This is, again somebody else, a 94-year-old male Ethiopian priest fully independent, fully ambulatory, he lives at home, walks around, ischemic gangrene of a previous hallux and toe amputation sight. You did have a percutaneous treatment six months ago, he prays everyday and he is otherwise well except for his diabetes and you can see here his lesion completes superficial femoral artery occlusion here all the way down including popliteal extending into his tibial vessels and so a variety of devices were used and ultimately at the end of the day we got flow restored down beautiful single were serving all these obviously the cost, floor time quite extensive sixty five minutes cost of contrast, two hundred and thirty CC’s but certainly the ultimate result is priceless.

    The, again another example the patient with sever calcification same thing very, very calcified lesion and ultimately after angioplasty, excellent result. So ultimately how do we decide where patient considerations, lesion consideration and how good the operator is, we look at functional status, comorbidities as I alluded to before, whether the patient is ambulatory or marginally ambulatory. The location, length of the lesion whether it's an occlusion or stenosis, multilevel versus single level these are all the things a vascular surgeon considers and ultimately you have to restore post-op flow because this is what we want to avoid and the reason why it's because of many of these patients who end up with one amputation will end up with either a contralateral amputation or a conversion to an above knee amputation in two years. This is excluding obviously the one third of patients who go on to die after an amputation.

    Who wins, well this is a largest randomized trial comparing angioplasty to a bypass surgery with excellent follow up. Again half of the patients dead at five years and overall if you compare angioplasty versus bypass surgery no difference in amputation, free survival, overall survival, a slight increase in overall survival beyond two years favoring bypass surgery, higher hospital cost as you would expect with bypass surgery in the first year but because those patients with endovascular intervention come back over and over for repeat interventions that causes equalized by three years and again amputation is associated with the worse quality of life. Overall balloon angioplasty, percutaneous endovascular intervention is significantly less expensive and less morbid in the short term and should be offered as first line treatment in those patients whom you expect are going to live less than two years.

    This is all in the horizon, so in summary endovascular procedures are here to stay, excellent results, over and bypass is here to stay, excellent results and the choice should be based on multiple considerations, you should not divorce the two in terms of versus, open versus endovascular but we should be talking about the two together just like we talk about statins and beta blocker statins and aspirin and it really is an open highway of options which ultimately result in everyone’s goal of reducing the rates of limb amputation in this country. Thank you so much for your attention.