Good day! This is Dr. Allen D. Hamden, MD. I am a surgeon at the Beth Israel Deaconess Medical Center where I serve as the director for clinical research. Todayâs lecture is on the indications, risks, and outcomes of lower extremity revascularization in patients with peripheral vascular disease.
The diagnosis of peripheral arterial disease ranges from 1-20% depending on the population you choose, risk factors, and the diagnostic techniques. The ratio of symptomatic to asymptomatic can be as high as 1:6. For every patient with claudication, there are another 3 who are estimated to have asymptomatic peripheral arterial disease. Basically, anyone with an ABI of 0.91 is considered to have peripheral arterial disease.
With the increasing age of the population in the United States, the prevalence of intermittent claudication is markedly increased. As you can see, as you get into the greater than 70 age group, the total number of patients with peripheral arterial disease is in the 4-5 million range.
This is just another depiction of as the population ages, the percentage who has peripheral arterial disease increases. This is also seen in both men and women.
The risk factors for atherosclerosis are included on the slide. As you can see, smoking is at the center of the problem as one of the most important things we can affect in our patients. On the left, age, diabetes,
obesity, and genetic conditions contribute to the development and progression of atherosclerosis. On the right, dyslipidemia including high triglycerides, high cholesterol, hypertension, the fairly rare hypercoagulable states, and then potentially hyperhomocysteinemia can also contribute to atherosclerosis.
Atherosclerosis can manifest at basically any arterial location; cerebrovascular manifestations would either be strokes or TIAs, in the coronary circulation, Q-wave MIs or non-Q-wave MIs or the unstable angina syndromes, renovascular hypertension or intestinal ischemia which is much less common than the other conditions listed above, and then in the lower extremities certainly claudication and potentially progressing to critical limb ischemia, rest pain, and gangrene.
This is a very simplistic depiction of the pathogenesis of acute ischemia. It basically starts with an atherosclerotic plaque which can be somewhat stable even if it is hemodynamically significant. Then the plaque can fissure or rupture and platelet thrombus forms on top of the plaque further increasing the luminal narrowing, and this can change into a worse or stabilized plaque or lead to in situ thrombosis of the vessel where there is complete occlusion acutely.
When you look at the overall group of patients with peripheral arterial disease, a very small percentage will have either severe limb ischemia, chronic or acute. Most patients will either have stable claudication or no symptoms at all.
This slide depicts 5-year outcomes of patients who were very closely monitored who had the starting diagnosis of just peripheral arterial disease and claudication. As you
can see, over 70% stayed stable, about 15% got worse, but only 7% needed bypass surgery and 4% needed major amputation. I generally tell patients who has claudication that the chance of them needing an amputation is about 1% per year, and that is roughly the same who will need some sort of revascularization 1-2% per year. Thus it is important to address the risk factors.
It is important to differentiate intermittent claudication, the vasculogenic claudication due to arterial circulation from some of the other conditions that could cause leg pain. The symptoms are generally described as an aching pain, sometimes heaviness or tightness or a cramp. It must be with exertion cramping and the large muscles at rest is not claudication. It has to occur in the large muscle groups; buttocks, calves, etc and not in the joints. This is sometimes difficult to differential in people with severe arthritis. It should be very reproducible from one day to the other. So, a patient who claudicates every time they walk up a certain hill in their neighborhood, it should happen every time they do it and not every other day or once a week. If patients describe very intermittent type symptoms, you have to question the diagnosis. Generally, the pain or cramping should resolve completely in about 5 minutes at most. I also like to ask them if they have to sit down for it to go away; that often indicates that they have spinal stenosis if they must sit down although they could have arterial circulation issues.
When trying to differentiate more severe conditions of lower extremity ischemia such as rest pain, this pain is different than that seen in claudication because it does not require any exertion for it to occur. Patients usually describe it as a pain although sometimes it is a numbness and it is seen over the metatarsal heads on the dorsal surface, worse with mild leg elevation. They identify it when they go to sleep since their legs are always elevated, sometimes they will tell you that they have to sleep in a chair with their legs hanging down. It often wakes them
up. They feel much better when they let their legs hang down, and in fact they will tell you that they often get up when they are sleeping, walk around a little bit, and it makes them feel better.
Certainly, if you see ulcerations or gangrene, it is a much easier diagnosis than trying to sort out rest pain in someone who has arthritis and who may have foot neuropathy of diabetes. Generally, the ulcerations are found distally. They are either at the end of the toes or over the bony prominences. It can present as a dry black eschar. It can either have intense pain in early stages or as the toe petrifies, there may be no pain related to toe specifically.
I have a particular interest in diabetes due to the fact that my institution is associated with the Josline Clinic and a high percentage of our patients have diabetes. It accelerates atherosclerosis several fold, increases the risk of coronary or ischemic events, there is a higher risk of stroke and the strokes are worse, and peripheral arterial disease often develops a decade earlier. Usually, you will see patients in the 50s or 60s who have diabetes presenting with lower extremity ischemia whereas in the nondiabetic population, which is usually the smokers or patients with high cholesterol, you will often see them in the late 60s or early 70s.
I would like to talk about some of the myths of patients with diabetes and vascular disease. They do not have intrinsic small vessel disease. They have a different pathobiology that will be described later but in and of itself, this idea that they have occlusion of their small vessels, which precludes healing of amputations or precludes successful bypass is wrong. There is also a feeling among people who do not routinely work with those with diabetes that when you try to revascularize them, it is not as successful as those in patients with diabetes. There is also a major issue with concerns about operating on patients with diabetes from the standpoint of cardiac risk and mortality from surgery. In fact if done properly, they can have the same or better mortality than in patients without diabetes.
Patients with diabetes who present with vascular disease, however, have an incredibly dismal 5-year survival, worse than some cancers. In other words, a patient who has diabetes who I do a bypass on, has a 5-year survival of about 50% and that is basically due their other comorbidities such as cardiac and cerebrovascular disease and that has not changed over the last decade.
To sort out this issue of the microcirculation, a number of investigators looked at amputation specimens and also extensive noninvasive testing and angiograms to once and for all prove that there is no such intrinsic disease or higher resistance of the small vessels, i.e., the arterials and the capillaries.
These are just studies if people are interested in looking at that essentially proved that there is no small vessel disease. My chairman, Dr. LoGerfo that you see on the third citing was influential in this education.
1. Conrad MC â Large and small artery occlusion in diabetics and nondiabetics with severe vascular disease. Circulation 1967; 36:83-91
2. Strandness DE Jr., Priest RE, Gibbons GE â Combined clinical pathological study of diabetic and nondiabetic peripheral arterial disease. Diabetes 1964; 13:366-72
3. Menzoian JO, Lamorte WW, Peniszyn CC, McBride KJ, Sidawy AN, LoGerfo FW, et al â Symptomatology and anatomic patterns of peripheral vascular disease: Differing impact of smoking and diabetes. Ann Vasc Surg 1989; 3:224-228
4. Goldenberg SG, Alex M, Joshi RA, Blumenthal HT â Nonatheromatous peripheral vascular disease of the lower extremity in diabetes mellitus. Diabetes 1959; 8:261-73
Now, saying that there is no small vessel disease is true but claim that patients with diabetes are the same as those without is wrong. There are major differences in the endothelial cell dysfunction even in those who do not have the diagnosis yet of diabetes but who will progress to diabetes. There is major thickening of the basement membranes of the capillaries. There is polyneuropathy which will be described later.
In essence, what is best described as the pathobiology of the foot is markedly altered in those with diabetes. Polyneuropathy accounts for the higher rate of ulceration at a given level of insufficiency. In other words, if you have two patients; one with and without diabetes who had 70% of their circulation intact, the patient with diabetes will be much more likely to develop an ulcer than the patient without for reasons related to the altered biology of the foot.
This is a description of the changes in the foot. There is a major loss of the pain receptors as well as the inflammatory response. This means that a patient could have a foreign body with pus in the plantar surface of the foot and not even amount an erythema or a white count. There is shunting of blood from the arteries to the vein leading to decreased tissue perfusion. There is thickening of the basement membrane as said on prior slides. There is a cavus deformity with increased pressure under the metatarsal heads leading to the mild perforance ulcer, the metatarsal head ulcer. There is marked decrease in sensation accounting for repetitive trauma that the patient with diabetes is not aware of, and then subsequently they have ulcer breakdown and then the toes are curled in the claw position. Certainly, the Charcot deformity is the outside scope of this presentation but that is another manifestation of the changes in the structure of the biology of the foot.
In the macrocirculation, the pathology of the stenotic or occlusive lesions is not different than in patients with and without diabetes. It is basically the same thing which is atherosclerosis.
However, the pattern of disease in macrocirculation is different. In general, patients who are smokers or have high cholesterol have disease in their iliac vessel and their proximal mid superficial femoral artery. Thus, patients with diabetes are often open down to their popliteal artery but then have tibial disease. They also very commonly have sparing of the dorsalis pedis artery making it a very good target for bypass.
Some general rules, both for those with diabetes and without. If they do not have a palpable foot pulse of both their dorsalis pedis and their posterior tibial locations unless the patient has significant swelling which complicates the physical exam, that is not normal. A hand-held Doppler is an incredibly sensitive test, so if you just hear a signal, that does not mean that the patient has adequate circulation. Patients who have just collateral vessels of the dorsalis pedis, may often have a loud Doppler signal. It is the character of the signal that is more important and this is better covered on my other lecture on the noninvasive evaluation of peripheral vascular disease.
Another thing that can fool clinicians is the location of an ulcer. For instance, the standard location for neuropathy and ulceration is over the metatarsal heads as described before. This can be in a patient with completely normal circulation and palpable pulses. However, just because it is in a neuropathic location, do not assume that it is only due to myopathy. There is a very high percentage of patients who have a combination of neuropathy and ischemia, thus you always have to evaluate for potential ischemia.
This is a standard location of a neuropathic ulcer. This is in a patient with osteomyelitis where the probe goes directly to bone, but in fact, this is a patient who also has significant arterial ischemia.
Another rule of thumb is an ulcer that is present for more than 2 months until you prove otherwise, has some ischemic component. Also, true gangrene of the toe as was seen on the other slide is almost always ischemic. It can be seen in repetitive trauma in patients with normal arterial circulation but that would be much less common.
It is important to have a treatment plan when you see any patient with vascular disease. If the patient has infection, that needs to be drained immediately regardless of whether they have ischemia or not. However, the flip side is in a patient who has the dry black eschars, especially healed eschars, do not start debriding them until you fix the circulation because all that will happen is you will remove the dead devitalized tissue and then it will desiccate beneath and further progress. It is very important to work with vascular surgeons who are familiar with revascularization either bypass or angioplasty, and the techniques of digital subtraction, angiogram is important, especially looking at the vessels below the knee in those with diabetes. Once you control the forefoot sepsis, you can reconstruct the vessels and then you need to plan the completion foot procedure. So, for instance, if the patient has an infected toe with plantar tracking, they may need an open ray with drainage, and then after control with antibiotics and the drainage procedure, they may need a bypass, and subsequently they may need closure of that ray or a transmetatarsal amputation.
We have had quite good success with the so called multidisciplinary approach which includes vascular surgeons, podiatrists, plastic surgeons, and the specialized nursing care unit. Just fixing the circulation is not enough. You have to prevent the ulcers by offloading pressure points and so it good to get your team involved even if it is not for a formal consultation on any cases that are not standard.
The revascularization whether it is a bypass or angioplasty should be performed before the final foot procedure, but that does not mean if they have sepsis and infection of the foot, that you wait until the circulation is restored. That is always treated first. We found over the course of thousands of foot amputations that if you try to do a foot amputation and it does not heal because of circulation issues, then you try to fix the circulation after the fact you end up losing a level, in other words, you may go from healing simple toe amputation to requiring the ray or transmetatarsal amputation, where from healing a transmetatarsal amputation to requiring a below-the-knee amputation. You try to do both these procedures during the same admission if possible.
What type of revascularization is chosen by the surgeon depends both on the lesion location and whether it is in arterial tree as well as what you have to use for conduit, i.e., available vein. So, it is important to establish inflow, inflow means, bringing blood from elsewhere to the groin or to the femoral artery. This can be done either by iliac stents, aortofemoral bypass or ileofemoral bypass, and in some situations even bringing blood from the axillary artery down to the groin.
Once you are sure that inflow is adequate either with surgery or angioplasty or knowing that from a physical exam or ultrasound study, then you have to assess for outflow or runoff issues. Outflow basically indicates any disease from the femoral artery down. Outflow issues can be treated by bypass from the groin down to the popliteal artery such as femoral popliteal bypass or to any of the tibial or foot vessels, which is much more commonly seen in the patients with diabetes.
So general rule, as stated above the nondiabetic patient has disease in the iliac vessels or the superficial femoral artery. Patients with diabetes often have disease below the popliteal artery so called trifurcation disease. Those patients may have a fairly strongly palpable popliteal but absolutely no foot pulses and very weak Doppler signals.
Regardless of the location of the bypass except when you are doing an aortobifemoral graft, the vein will perform better than any sort of prosthetic graft, Gortex, etc. Patency rates of both femoral to popliteal bypasses as well as the more distal tibial bypasses will be about 70-80% after 1 year and about 60% in 5 years. However, as I stated before, in all patients who need a bypass over the course of 5 years, at least 30% of them will be deceased and if they have diabetes in addition, almost half will be deceased, so that plays a role in choice.
When you are looking at the measures that vascular surgeons use for success, there is both patency of the bypass graft meaning that the graft is still functioning and then there is limb salvage which means that they have not had a major amputation, either a below-the-knee or above-the-knee amputation. Limb salvage includes patients who have transmetatarsal amputations that is considered safe. It always exceed patency; however, and that is basically that you may do a bypass healed foot wound, and then subsequently the graft will fail but the limb may stay on for a period of time even with an occluded graft.
This is a study that I will go over related to our institutions results in doing bypasses in patients with diabetes that detail over a thousand bypasses in patients with diabetes down to the dorsalis pedis artery.
A surgical approach to the bypass as you can see here, this is the dorsalis pedis artery exposed on the dorsum of the foot. We often can do a bypass so called short graft from the popliteal artery down to the dorsalis pedis. A vein is used exclusively. A flexible approach means the vein can be reversed. It can be taken off the common femoral artery. It can be taken off lower depending on the clinical situation. We can do the so-called in situ grafts where basically the vein remains in the saphenous bed except at the proximal distal anastomosis. The veins can be flipped around or the valves can be lysed. We often use angioscopy which is a scope placed inside the vein to evaluate for areas of stenosis and webbing, and it is very important to pay meticulous attention to closure of the wound, especially in the foot.
This is just to show that over 90% of the patients who have dorsalis pedis bypass as well as diabetes, and you can see the other standard risk factors.
In addition, as you can see on this slide, the majority of patients will undergo bypass for wound loss indications such as ulcers or gangrene
This slide is not crucial to memorize, but it just is important to show that it is ideal to work with vascular surgeons who have expertise in doing a number of different types of constructs using arm veins, lesser saphenous vein, etc.
Over here, you can see that the major complication rate is actually quite low. Only 1% of patients succumb to the surgery or mortality of less than 1%, but a number of them will have problems with heart attacks, renal failure, wound problems, etc, but overall it is a very safe procedure.
This details the patency rates. The difference between the primary and secondary patency just so you understand these terms. Primary is a graft is placed, nothing else is done to it and it stays patent. Secondary patency is a graft that is initially patent and then develops an areas say a stenosis in the mid graft and you fix that either with an angioplasty or patch repair of that vein, and then it subsequently stays patent for a longer period of time. Overall, you can see here that the patency rate at 5 years is over 60% as I detailed in prior study.
As I stated before, the limb salvage is always higher than the patency rate, and you can see here that almost 80% of patients who have a dorsalis pedis graft will still have their leg at 5 years.
So in conclusion, the dorsalis pedis bypass is very successful and very safe and leads to very high limb salvage rates, and has to be an armamentarium of any surgeon who is dealing with patients with diabetes.
So in general, because patients have different disease when they have diabetes, vein grafts are really the primary mode of treatment. The results of angioplasty using balloons and catheters for tibial vessels are sporadic but generally with poor long-term results. However, it may be indicated in certain patients especially if the goal is just to heal an ulcer or prepare for a foot procedure in someone who has an incredible surgical risk, but these are certainly the type of environments that you want to be practicing in if you have patients with diabetes where the surgeons or the interventionalists are very skilled at choosing which method is the proper one.
one other thing that I wanted to cover was this whole myth that patients with diabetes have an incredible mortality rate for any surgery, especially vascular unless they should just go directly to amputation. Diabetes is still listed as a major risk factor when you look at patients undergoing surgery.
We looked at over 6000 patients who underwent vascular surgery and you can see over 60% had diabetes.
As you can see here, a large percentage of patients have cardiac disease such as CHF, MI, or hypertension.
You can also see here that patients with diabetes present earlier than those without diabetes, but also will still have significant risk factors such as MI and CHF.
We looked at mortality rate and you can see here that patients with diabetes had even a lower mortality rate than those with no diabetes although they may have had higher rates of postoperative MI and CHF.
When we looked at our complicated statistical packages, we found that the only thing that really predicted higher death rates after bypass surgery was patients who were on dialysis and those patients who had congestive heart failure.
In fact, diabetes in this study which is over 6,000 patients, had an inverse effect on mortality. In other words, they actually had a lower rate of dying from the vascular procedures. Now, I am not claiming that it is good to have diabetes, but it certainly just opens up the options for these patients and it is not uncommon for me to see a patient who is a very good candidate from a standpoint of arterial reconstruction just because they had diabetes or told that a bypass will not work, and also that they have a high chance of dying from the surgery, and this is still occurring across the country today.
However, as I said before, almost half of these patients will be deceased 5 years after their vascular procedures. Patients without diabetes fare much better from a survival standpoint in the long run. It is probably due to the progression of coronary as well as cerebrovascular disease and also the higher risk of them being on the need for dialysis.
Some general conclusions; patients with diabetes do not have small vessel disease, bypass with their own veins mainly to the tibial vessels is a really durable procedure and allows for a number of foot procedures to be performed successfully, and less invasive modalities such as angioplasty and stenting are only suitable currently in special situations but it is certainly good to practice at a hospital or in network that has all these options.
Patients with diabetes can be expected to have a low morbidity and mortality rate from a number of different vascular surgery procedures. It really does not currently, in our minds, an independent risk factor for perioperative problems.
When seeing any patient with foot ischemia, they also have concurrent sepsis that needs to be dealt with first; that does not mean dried eschars, that means drainage of infection. Once that is done or while it is being done, it is important to evaluate as well as to treat the ischemia aggressively either with a bypass or angioplasty. We find that a multidisciplinary approach is the key. Once the revascularization procedure is intact, then a secondary foot procedure can be performed, and then most importantly is adjusting any risk factors to prolong the patientâs life such as cholesterol problems, smoking patterns, etc and to educate the patient and the family on proper foot care, proper shoes, and get them hooked up into a program where they are seeing both the vascular surgeon and their podiatrist regularly.