Multidisciplinary Peripheral Arterial Disease

What are some of the key findings of pedal peripheral arterial disease (PAD) that you see in the office setting?

Bar-David: Key findings include absent pedal pulses, thin and tight shiny skin, cool toes, claudication, and rest pain, especially at night. On patients that have sclerosis on plain film radiographs, I will always ask for a vascular clearance if I am planning any surgery, even if they have a palpable pulse. I want to make sure that flow studies are performed on the digits. Also, I would not advise using a tourniquet in this case.

Markinson:Patients who are aware they have PAD and have had it correctly tested and diagnosed usually have overt clinical findings like the ones mentioned by Dr Bar-David. Then there is another subset of patients who are under the impression they have poor circulation because they may have complained to their primary care physician of leg pain when walking, or perhaps some swelling, and without any testing they are told they have poor circulation.

Landsman: Aside from diminished or absent pulses, I think that one of the key clinical signs of pedal PAD is sudden onset of deep wounds (particularly if preceded by a blister), apparent subcutaneous fat pad atrophy, and feet that are cool to the touch. Chronic PAD is often more difficult to determine than acute PAD in that the gradual onset of symptoms is frequently so subtle.

Dayal: We see various manifestations of peripheral arterial disease in our office. The manifestations can run from claudication to ischemic rest pain to minor tissue loss and major tissue loss. Patients with ischemic rest pain have pain constantly in the forefoot and toes, and dangling the extremity usually relieves this pain. They will also have some dependant rubor and the extremity may become very pale on elevation. Patients may also have minor tissue loss as well as major tissue loss or gangrene. Minor tissue loss may be evidenced as ulcerations or wounds that do not heal for weeks despite adequate local wound care. Major tissue loss may be manifested as forefoot gangrene or heel gangrene or both.

Are there any tools that you use to assess for PAD in the office setting?

Hamdan: The first important tool is a good history. The second is the physical exam, including the presence or absence of dorsalis pedis and posterior tibial pulse. If the pulses are not normal or easily palpable, then handheld Doppler evaluation is the next step. The first finding would be the presence or absence of Doppler signal at those locations, and then you would also look for the type of signal (ie, monophasic or triphasic). A triphasic signal with crisp upstroke and then reversal of flow would be consistent with a normal circulation at that location. Routine ABI, which can be done with the Doppler probe and a pressure cuff in patients with diabetes, is frankly sometimes inaccurate and difficult to interpret because of noncompressible vessels, but that is also a reasonable baseline.

Markinson: The palpation exam and the cursory “back of my hand” temperature exam seem to be reliable in nondiabetics. I am, however, finding increasingly that palpation exams in diabetics are unreliable. Diabetic patients with normal exams may have significant occlusive disease. A Doppler lower extremity exam, with segmental pressures, toe and ankle brachial indices, and pulse volume recordings are my standard tests for initial assessment.

Landsman: If I am suspicious of PAD and unable to feel both DP and PT pulses, I normally begin my assessment with a handheld Doppler. I also consider capillary refill and skin temperature measured with an infrared thermometer.

Bar-David: I refer for vascular evaluation quickly because I cannot primarily treat PAD. Many clinicians are performing noninvasive testing in the office setting, such as ankle-brachial indices (ABI) and pulse volume recordings (PVR). This is something to consider as long as you have proper follow-up for treatment if there are abnormal findings.

Do you think there is a role for screening for PAD?

Hamdan: There certainly is a role for examining foot pulses in every patient and taking an appropriate history. As far as being more aggressive with noninvasive arterial tests or other tests such as MRA or CTA, in the average patient without symptoms or findings, that would not be necessary. The major reason to identify a patient as having peripheral arterial disease is because atherosclerosis is a global manifestation, and the identification of PAD on a foot exam with a history would be an indication for risk factor modification. This would include smoking cessation, discussion with the primary care doctor about institution of antiplatelet therapy, and also institution of statin therapy.

Dayal: Yes, especially in patients with diabetes and other risk factors for PAD, including hypertension, hypercholesterolemia, and tobacco use. An ABI is very useful to screen for occult cardiovascular disease and allows us to determine the degree of PAD. This is especially important in diabetics since their first manifestation may be limb-threatening ischemia. Therefore, identifying PAD by screening will allow for cardiovascular risk factor modifications to prevent progression of disease.

As a radiologist, what type of advanced imaging do you feel is helpful in diagnosing and assessing PAD?

Sperling: Peripheral vascular computed tomographic angiography (PV-CTA) can be a very helpful diagnostic tool for PAD. Studies show that about 3 to 4 million symptomatic PVD patients are misdiagnosed or go untreated, and about 6 million patients are asymptomatic and, therefore, untreated. PV-CTA is an excellent noninvasive modality to identify this large, asymptomatic, yet at-risk population. I feel that earlier PVD diagnosis and treatment through use of PV-CTA has the potential to significantly improve patient outcomes. It is a very sensitive and specific test that you can employ to provide confidence for preprocedural planning.

Faintuch: Angiography, the traditional gold standard, is no longer indicated as a routine diagnostic study. Because of its invasiveness, it is now reserved for patients with known disease, when an associated endovascular procedure is likely necessary. Doppler ultrasonography is readily accessible and inexpensive and does not require ionizing radiation or intravenous contrast agents. However, better sensitivity and therapeutic confidence can be obtained with CT or MR angiography. CT and MR angiography are the “advanced imaging” in imaging assessment of PAD.

What other medical conditions do you often see that correlate with PAD?

Goldin: Coexisting risk factors that are commonly seen with PAD are diabetes and coronary artery disease.

What type of medical management do you use for patients with PAD?

Goldin: Treatment of any underlying PAD risk factor is key. Glucose, lipid, and blood pressure control medications, along with appropriately indicated anticoagulants, are standard. However, I do not routinely use medications specifically for symptom management in PAD. Some physicians will try cilostazol (Pletal) or pentoxifylline (Trental) for patients with intermittent claudication.

After making a diagnosis of PAD, what is your next step?

Landsman: I usually move right to the segmental pressure and arterial Doppler exam, performed by our vascular surgery department. If there is evidence of PAD, I refer them for immediate vascular examination. Experience has shown that rapid intervention usually results in the best outcomes. PAD is essentially a gradual starvation of the tissues. During this time, the foot is highly susceptible to further injury as well.

Bar-David: I will refer these patients to the vascular surgeon for evaluation and then collaboratively discuss the patient’s alternatives and monitor for any further changes. Comorbidities, such as impaired renal function and cardiac problems, are important risk factors, as vascular disease in one system is most often accompanied by vascular disease in another, making treatment decisions complex.

Dayal: Determining the next step is based upon the patients’ presenting symptoms and their comorbid conditions. If the patients have lifestyle-limiting claudication but are poor candidates for intervention, we may advise them to pursue exercise and medical risk factor modification. Similarly, if the patients are asymptomatic and PAD is discovered as part of a screening test, we will advise them to undergo risk factor modification, exercise, and smoking cessation. However, if the patients’ symptoms are severe claudication, ischemic rest pain, or major and minor tissue loss, we advise interventional treatment. Critical limb ischemia, defined as rest pain and tissue loss, mandates aggressive treatment to prevent limb loss. In those patients, we proceed to angiography and then pursue endovascular or open surgical revascularization based on the severity of disease and the patients’ comorbidities.

Markinson: If patients are asymptomatic from a lower extremity point of view, I will make sure their primary care physicians are aware so they can do appropriate screenings for carotid and coronary arteries.

Hamdan: The next step regarding the confirmed diagnosis of PAD depends on symptoms or need for foot procedures. If the patient is completely asymptomatic and has no claudication, no rest pain, and no ulcers, then risk factor modification as described in the other questions would be the next step. If the patient has PAD and symptoms, if they are just claudication, then conservative management with medications and exercise would be reasonable. If there is severe claudication or foot lesions or need for foot reconstruction, then the next step is generally an angiogram with evaluation for endovascular therapy versus subsequent bypass.

What endovascular technologies do you use to manage peripheral arterial disease?

Dayal: We utilize all methods that are currently available, and the majority of our treatments revolve around endovascular stent placement or angioplasty. We also utilize directional and rotational atherectomy in situations that we believe it is appropriate. The way we decide about which technology to use is based on the location of the disease. If the location is in the iliac arteries, we use stents routinely as opposed to angioplasty or atherectomy. In the situation of femoral and popliteal disease, we utilize stenting or atherectomy dependant on lesion characteristics. If the disease is located at bifurcation points, then we utilize atherectomy extensively. If the diseased segment is long and calcified, frequently atherectomy is not sufficient, and we will use stents in those situations. For infrapopliteal disease or disease below the knees, we use angioplasty and atherectomy preferentially because stents in that position do not work as well as they do above the knee.

Hamdan: There are myriad technologies, and it can become very confusing. The first tenet of any planned procedure is to have the appropriate indication. In other words, if the patient does not have palpable pulses but does not have any lesions or symptoms and is not pending any major reconstructive surgery, only risk factor modification needs to be employed. If the patient truly needs a revascularization and has the appropriate anatomic findings for which he or she would do well with endovascular therapy, balloon angioplasty and selective stenting are still the standard of care. Multiple therapies such as atherectomy and laser have been touted as major improvements, but frankly the results in the real literature do not warrant their routine use. In a patient who needs a major foot reconstruction, endovascular therapy is still an option, but unless you can restore mainline flow with palpable foot pulses, then a bypass would be more appropriate.

Is there is a consensus on drugeluting versus bare stents, and what are the benefits?

Hamdan: In the periphery, there is no consensus currently on drug-eluting stents. There are very few clinical trials; the major clinical trial that will hopefully give us the significant information is not completed. Its data are being processed. It is likely that drug-eluting stents would increase the patency rate. As has been seen in the coronary literature, there is concern that it may increase the acute thrombosis rate, although that has not really been seen in the initial information. Currently, the standard would be to perform an angioplasty and, if there is a flow-limiting dissection or residual stenosis, place a bare metal stent.

Dayal: The main benefit to drugeluting stents and balloons is that the medication delivered may prevent re-stenosis, which is the Achilles heel of any endovascular intervention. Drugeluting stents are being investigated in several clinical trials for use in the lower extremities; however, they are not Food and Drug Administration (FDA) approved currently. We are participating in one of the trials utilizing drug-eluting stents in the femoral-popliteal region; however, the results of the trial are not yet known. Data from prior trials utilizing drug-eluting stents have been fairly mixed. The initial trials of drug-eluting stents for femoropopliteal disease did not demonstrate any benefit for the use of drug-eluting stents. However, subsequent trials have shown that they may be of some benefit. Therefore, it is important to remember that while drug-eluting stents and balloons may prove to be of great value in the future, the clinical trial data are not finalized, and drug-eluting stents should only be used as part of a clinical trial.

When do you proceed to lower extremity bypass grafts?

Wyers: Initial (and sometimes secondary) treatment of patients with claudication is almost always an endovascular approach, saving bypass for recurrent significantly limiting symptoms. I have also adopted this approach for patients with minor tissue loss if in-line flow can be established to the foot. There are many things that go into making the ultimate decision—operative risk, preoperative ambulatory status, quality of venous conduit and target for bypass, extent of tissue loss, and extent of popliteal/ tibial vessel involvement. All other factors being equivalent, in my experience patients with longer segment occlusions (especially involving popliteal and tibial vessels) and with more extensive tissue loss (needing TMA or with heel ulcer) do better with distal bypass.

Dayal: We utilize lower extremity bypass grafting usually when endovascular methods have not been successful. In certain situations, we preferentially use lower extremity bypass grafting as a first line of therapy; however, the vast majority of the time, endovascular treatment is the firstline treatment. Approximately 80% of our patients are treated with an endovascular method only. The situations in which we use open surgery first are when patients have complete occlusions that cannot be traversed. Additionally, if the patient has had an endovascular intervention that has failed quickly and the patient still requires revascularization, then we proceed to open surgery. Lastly, if the patient is an otherwise healthy younger patient with good conduit and is a good operative risk, we advocate open surgery as first-line treatment; however, this is becoming less and less common as endovascular technology improves.

How do you handle a patient with PAD who has a lower extremity wound?

Markinson: In nondiabetics, lower extremity wounds related to PAD are usually extremely painful, so they are referred quickly for vascular intervention. This is also the case with rest pain. The surgical treatment of patients who are claudicators is more of a “quality-of-life issue” than a true emergency. What I do know for sure is that the still pervasive advice of “keep on walking” to improve the circulation does not work.

Bar-David: If they have a wound, it is usually a co-management situation. In some cases, the vascular surgeon may take care of the wound and PAD. In others, I will treat the wound and the vascular surgeon will monitor or intervene depending on the healing and personal situation of the patient. As mentioned earlier, comorbidities are important.

Dayal: We utilize a multidisciplinary approach to wound care management for patients with lower extremity wounds with peripheral arterial disease. We collaborate closely with our wound care and podiatry colleagues. We use a variety of topical wound care agents such as antibiotic creams, debriding agents, as well as silver-impregnated products as appropriate. In the situation of severe forefoot sepsis, we will proceed with debridement and limited amputation followed by definitive amputation after revascularization. If at all possible, we proceed with revascularization prior to debridement or amputation in order to maximize the chances of limb salvage.

Landsman: Most importantly, I try to restore flow when possible. Some of the more recent studies have examined the use of vasodilators, sequential nerve blocks, and hyperbaric oxygen therapy. I have employed all of these methods in the past and have seen improvement with all of them.

Wyers: Judicious debridement to clear deep or significant local infection should be done with the final reconstruction options in mind. Ideally, extensive debridement should be delayed until revascularization (operative or endovascular) can be accomplished. For more chronic wounds or open wounds after revascularization, I use a variety of local wound treatments, including conventional wet to dry dressings, iodosorb, aquacel, enzymatic debriding agents, and topical antibiotic ointments. Appropriate offloading is also very important.

Is there a difference in your management if the patient with PAD also has diabetes?

Markinson: In my experience, a lower extremity with intact skin envelope can withstand a considerable amount of circulatory insufficiency with moderate clinical exam findings. Of course, neuropathy plays an important role in developing ulcerations. Once a wound develops, however, what was once enough blood flow to sustain the extremity before a wound is not enough to heal the wound. Once a wound occurs, a vascular surgery consult is the rule. Vascular intervention before a wound may not have been required, but it may indeed be necessary to get the wound closed.

Landsman: PAD becomes further complicated when diabetes is present because of the potential dangers associated with basement membrane thickening. Because the PAD patient is already at risk, the problem is magnified in the presence of diabetes. Proactively, I will take extra steps to protect the feet, before the problems develop.

Bar-David: Diabetes does not change the course significantly. However, it is a significant comorbidity that will further delay healing and worsen the overall prognosis if there is a wound. The question is whether a vascular surgeon would be more aggressive in “prophylactic” revascularization in patients with diabetes and PAD without an existing wound, because the complexity of healing is increased with DM.

How do you proceed with amputations in patients with PAD?

Markinson: The best management for amputation is making sure it does not happen. Both the patient and podiatrist must do their respective parts. In my opinion, way too many amputations are being done as a result of a nonaggressive, nonsurgical approach to common deformities, such as bunions and hammertoes. These often break down later and become infected, necessitating amputation. I have also seen many patients who have had positive signs of wound healing develop a wound infection and go to an emergency room where amputation was the first and only treatment consideration. This occurrence is way too common, and I fear that the current health care reform climate may cause much more of this to happen. Serial debridements and appropriate antibiotic therapy can result in much less tissue damage and functional loss. But who amongst us has not had a situation where the third trip to the OR has the anesthesiologist or some other doctor asking, “Why don’t you just cut the thing off already?”

Bar-David: You must have adequate flow before amputating. You may do an emergent incision and drainage, but then a rapid vascular evaluation is indicated. This type of tissue is starving for blood, and extensive necrosis of the plantar fat and all the other tissue will soon set in, which worsens the infection and increases the chance of limb amputation. Limb preservation requires a rapid response from all members of the team. You also must watch for anaerobic organisms in infections occurring with PAD patients. These should be covered for in the antibiotic regimen. I always involve an infectious disease specialist in the team. This will help you treat the patient better and more efficiently, especially when it comes to dosing antibiotics in renally impaired patients and those patients discharged home for antibiotics. Additionally, be careful not to use VAC therapy (vacuumassisted closure) with patients who have untreated PAD. This can only further necrosis. Evaluation for VAC needs to be carefully planned following revascularization as well, as the pressure may need to be decreased significantly.

Dayal: We proceed with major amputation when the degree of tissue loss precludes limb salvage. This situation may arise when there is gangrene involving the entire foot or when a functional foot cannot be salvaged because of the degree of tissue loss. If the gangrene is contained to the forefoot or toes, then we will proceed either with toe amputation or transmetatarsal amputation as appropriate. The situation of heel gangrene is especially problematic because if a large portion of the calcaneus becomes exposed, the extremity cannot be salvaged and major amputation becomes necessary. Obviously amputation is not performed until absolutely necessary and all other options have been explored, including revascularization, aggressive debridement, and long-term intravenous antibiotics.

Wyers: Uncontrolled sepsis and severe pain are clear indications for amputation. Short of these, every patient reaches the decision for major amputation at a different rate, and the decision must be individualized. Remember that the goal is a functional walking platform, so the ultimate recommendation for major amputation comes when I am convinced that the foot is not salvageable for that purpose. Frail patients with relatively stable tissue loss can often avoid amputation. In contrast, there is a small subset of younger, more robust patients who, despite the fact that they may be able to withstand multiple vascular and podiatric procedures, may do better with an earlier amputation.

Is there any type of footwear that you prescribe in patients with PAD with or without diabetes?

Bar-David: A soft, wide, extra-depth shoe with a plastizote inlay is what I recommend for these patients.

Markinson: I believe that the diabetic protective footwear currently available is good for any patient. However, female patients universally reject these shoes for aesthetic reasons, and their compliance with appropriate footwear is very low. I have many patients who wear their shoes only to their appointments with me!

Landsman: Regardless of whether or not diabetes is present, I almost always recommend roomy, stiff-soled shoes lined with salmon-colored plastizote. More importantly, I try to bring them back within 2 weeks so that I can examine the wear pattern in the insole, in order to catch new sore formation early. These individuals are also encouraged to examine their feet daily and are asked to contact our office immediately if they find any areas of concern.

What do you foresee as the “next frontier” in diagnosing and assessing PAD as a radiologist?

Sperling: With continued improvements in magnetic resonance imaging (MRI), the quality of MR angiography (MRA) has drastically improved. It is now possible to obtain very high-resolution arterial images. And as gradients get faster and stronger, and field strength increases, MRA imaging will improve. In many situations where invasive angiography was previously required, MRA (with or without contrast) can now give equally clear images noninvasively.

Faintuch: CT and MR angiography are the “advanced imaging” as well as the “next frontier” in imaging assessment of PAD. Each modality has its own advantages (eg, ability to image without contrast administration and no radiation exposure for MRA; faster and more accessible for CTA) and disadvantages (eg, MRI contraindications, such as metal implants and claustrophobia; need for potentially nephrotoxic contrast agents and radiation exposure for CTA). MRA and CTA are currently being used with very high diagnostic accuracy, but prospective randomized trials are still necessary to compare both modalities, as well as to establish their real effect on treatment, costs, and outcomes.