Current Concepts In Treating Ischemic Foot Ulcers

     When it comes to patients with ischemic foot ulcers, potential complications can be dire. Accordingly, it is important to have a firm grasp on diagnostic studies as well as current and emerging treatment options that may enhance outcomes for patients.      With this in mind, our expert panelists discuss a range of issues related to the ischemic foot.      Q: How do you approach/work up the ischemic foot ulcer patient?      A: David E. Allie, MD, works up such patients “very, very aggressively.” Of the approximately 180,000 to 200,000 annual amputations in the U.S., he notes that between 80 and 85 percent are preceded by an ischemic diabetic foot ulcer (DFU). Research indicates that following a below- or above-knee amputation, half of the patients will survive for three years and less than half will achieve mobility.      Since these patients may die from heart attacks and strokes, Dr. Allie says he initially performs a quick (5- to 10-minute) cardiac-carotid-renal-diabetic history and exam before he turns his attention to the foot. These patients will need revascularization so he will immediately start ASA 325 mg, Plavix 75 mg, antibiotics after C&S, and Metanx (Pam Lab) po bid. In regard to Metanx, he is “impressed” that its combination of vitamin B-6, B-12 and folic acid spurs wound healing by lowering homocysteine levels.1      For Marc Brenner, DPM, the most important steps are the history and physical exam. He says the exam must include palpating all pulses, assessing for capillary return and venous filling time, and, most significantly, obtaining the ankle-brachial index (ABI).      If he cannot initially palpate pedal pulses, Lawrence Karlock, DPM, will perform an arterial Doppler test with absolute toe pressures. Even when one is facing calcified lower extremity vessels, Dr. Karlock says absolute toe pressures may provide an accurate account of arterial inflow.      When it comes to treating foot ulcers, if one or both pedal pulses is not palpable, Mehrdad Zarrinmakan, MD, says an arteriogram is indicated. If pedal pulses are palpable, he says one should perform arterial studies.      Q: What value do noninvasive arterial studies play in the diagnosis?      A: Noninvasive arterial studies in patients with diabetes, with or without ulcerations, should be part of every practitioner’s approach, according to Dr. Brenner. He adds that podiatric physicians should measure ABIs and duplex scanning routinely for patients with diabetes.      Dr. Zarrinmakan likewise cites the importance of arterial studies, calling them “important and relatively inexpensive.” He says physiologic testing plays a major role in the diagnosis and follow-up of patients.      Dr. Allie immediately obtains the ABI and arterial duplex ultrasound to confirm but not completely localize all involved diseased vessels. Simultaneously, in one office visit, he obtains noninvasive studies, including carotid ultrasound, echocardiography and cardiac nuclear imaging, if indicated, to access the entire cardiovascular system. Dr. Allie notes having a low threshold for early hospital admission for patients with critical limb ischemia (CLI) and emphasizes intravenous anticoagulation, antibiotics and renal hydration, which prepare them for revascularization. Dr. Allie also obtains appropriate consultations with podiatry, cardiology, endocrinology and other specialists.      Although noninvasive arterial studies provide a general overview of the vascular inflow, Dr. Karlock says they can be misleading in some instances. He says a normal test will usually exclude any significant peripheral vascular disease (PVD).      Q: When do you consider arteriography? When do you consider a magnetic resonance arteriogram (MRA)?      A: Dr. Brenner calls ABIs of less than 0.6, along with rest pain and/or lesions, discoloration or claudication, “a red flag” for immediate referral to an appropriate PVD specialist. Following ABI and duplex scanning, a vascular surgeon would usually undertake MRA, CTA and a DS angiogram, according to Dr. Brenner. After performing these diagnostic tests, he says the vascular surgeon would usually perform interventional endovascular procedures as an alternative to bypass or possibly in conjunction with it.      Dr. Zarrinmakan considers an arteriogram when a patient requires revascularization. In patients with renal insufficiency, allergies to iodinated contrast and severe multilevel disease, he says MRA and ultrasound are excellent choices for imaging.      Dr. Allie “very rarely” uses MRA, even though he says it has merit in CLI patients with renal insufficiency. According to Dr. Allie, MRA is time consuming and limited in patients with stents, clips and pacemakers. Alternatively, one may can obtain new noninvasive, intravenous, 3-D, multichannel CTA in the outpatient office setting with scan times of less than 30 seconds, points out Dr. Allie. He says CTA has no metallic limitations and is more accurate today than single planar traditional hospital-based angiography without the risks of an “arterial stick,” such as bleeding, vessel thrombosis, hematoma or infection.       “I must emphasize that CTA is noninvasive. In 2007, no patient should undergo a primary amputation without at least a vascular surgical or interventionalist consult, vascular CTA and/or angiography,” adds Dr. Allie.      Dr. Allie notes the risks of CTA or angiography today are far lower than a below-knee amputation (BKA) or above the knee amputation (AKA), which have a 30-day preoperative morbidity/mortality rate of 10 to 40 percent. He emphasizes that the benefits of revascularization include more than 90 percent limb salvage rates with minimal risks such as morbidity/mortality rates of less than 5 percent. He says an aggressive approach towards angiography and revascularization is important.      In an 18-month study of a U.S. Medicare database of 417 CLI patients, Dr. Allie notes that he and his co-authors found that over 60 percent of the patients had a primary amputation as their first treatment. Additionally, the study found that less than 30 percent received a vascular or interventional surgical consult, and only 38 percent had an ABI and 16 percent had angiography.2      Q: What wound products do you utilize in ischemic foot wounds?      A: For Dr. Zarrinmakan, treatment of ulcers encompasses the broad categories of revascularization, antibiotics, topical wound care therapies and compression garments.      Dr. Brenner uses topical activated collagen preceded by Ocean Aid spray or foam (Ocean Aid). After taking appropriate cultures, if indicated, he starts with a systemic antibiotic such as amoxicillin/clavulanic acid (Augmentin, GlaxoSmithKline) or levofloxacin (Levaquin, Ortho-McNeil). He will switch these when culture reports indicate another sensitivity.      With over 25 years of experience in vascular surgery, Dr. Allie has used the whole gamut of wound care products and works closely with podiatrists. He advocates early revascularization followed by local wound sepsis-antisepsis control and aggressive early wound coverage with minimal debridement.      For all open wounds, Dr. Allie uses Dermacyn (Oculus Innovative Sciences) to achieve immediate local wound sterilization. Dermacyn, a recently approved superoxidized antiseptic solution, has been shown to achieve “exceedingly high” cidal levels against all bacteria, viruses and spores, including methicillin-resistant Staphylococcus aureus (MRSA), as reported in a recent randomized trial.3       “In my hands, Dermacyn has replaced all topical agents and solutions for ischemic foot wounds, and decreased the need for oral or intravenous antibiotics, hospitalizations and debridement,” notes Dr. Allie.      After this treatment, Dr. Allie says the revascularized, sterilized wound is ready for coverage, which could be with split thickness skin grafts (STSG), bioengineered skin or a wound vacuum assisted therapy with a Dermacyn-soaked sponge in the deeper wounds. He cites his recent “excellent” results with the early application of Apligraf (Organogenesis) in CLI patients after laser revascularization. He says he has also had success with Apligraf application in wound complications after coronary arterial bypass graft (CABG) and tibial bypass surgery.4,5      Dr. Karlock tries to keep the wounds clean, dry and uninfected. He also says clinicians should avoid debriding an ischemic wound to prevent adding “insult to injury.” He believes Betadine still plays a role until vascular bypass, etc. is undertaken. Dr. Karlock notes he also uses Iodosorb (Smith and Nephew) for these wounds. He avoids any aggressive wound enzymatic debridement.      Q: What new interventional procedures do you utilize?      A: For CLI revascularization, Dr. Allie uses several new products. He cites Excimer laser therapy for photoablation of atherosclerotic plaque and thrombus (clot), and the benefits of SilverHawk (FoxHollow) plaque excision. He also uses metal stents of sizes ranging from 2 to 22 mm and cryoplasty or cryotherapy, which delivers -10°C controlled balloon dilation to vessels to minimize injury and restenosis. Dr. Allie says mechanical thrombectomy removes recently formed clots and specialty balloons (cutting balloons) with small blades facilitating the treatment of calcified vessels.      In addition, he says one can facilitate interventional revascularization by using a host of new adjuvant technologies, including reentry catheters that permit wire crossing of long, totally blocked vessels, as well as distal protection devices or filters that facilitate the capture of macro- and microembolic debris that may result from the revascularization procedure.      Like Dr. Allie, Dr. Zarrinmakan cites the use of FoxHollow atherectomy and stents. He uses a vast variety of interventional modalities such as percutaneous balloon angioplasty and laser atherectomy. When such modalities fail or are not possible, he opts for bypass grafting or other surgical procedures.      Dr. Brenner says podiatrists should be aware of new alternatives to bypass and newer tools for revascularization so they can make appropriate referrals for patients who may benefit from these procedures. He cites Remote Endartectomy (Vascular Architects), a minimally invasive technique for treating femoral popliteal occlusive disease that a vascular surgeon would usually perform at the superficial femoral artery. With this procedure, the vascular surgeon can successfully excise large calcified plaques and strong results are not uncommon, according to Dr. Brenner.      Dr. Brenner suggests DPMs should also be aware of cryoplasty therapy (Boston Scientific), which he says offers promising results for treating popliteal and tibioperoneal disease.      Q: Do you have any insight on the timing of foot amputation and the bypass procedure?      A: “Amazingly, and this must be rectified, the facts are that 49 percent of the BK amputations presently done in the U.S. are being performed without even doing ABI studies,” asserts Dr. Brenner. “It is imperative that all diagnostic tests be performed by competent vascular specialists and/or radiological interventionists, who then should probably do endovascular procedures and/or bypasses to revascularize feet before any amputations are performed.”      Dr. Allie strongly suggests a bypass or percutaneous interventional procedure prior to considering amputation unless an obvious abscess or necrotizing fasciitis is present. He also recommends conservative, limited amputations when indicated as these procedures give the patient maximum opportunity to preserve tissue and function. Although he has advocated systemic hyperbaric oxygen (HBO) therapy, Dr. Allie has found 70 to 80 percent of the elderly CLI patients will have a contraindication or will not tolerate systemic HBO (due to CHF, pulmonary issues, etc.). He relates positive experiences with local extremity or topical oxygen therapy, noting he is encouraged with recent work at Ohio State where researchers are trying to provide the “science” of why this therapy works.      Avoiding amputation is possible with newer endovascular therapies, according to Dr. Zarrinmakan. He says one should perform revascularization as soon as one diagnoses an ischemic ulcer.      Dr. Brenner notes that one always obtains the best results in diabetic ischemic feet with multidisciplinary collaboration, including cardiology, internal medicine, vascular specialists, interventional radiology and podiatry. As revascularization procedures improve, Dr. Brenner believes there will be more cases of successful diabetic limb salvage and lower amputation rates.      Dr. Allie is the Director of Cardiothoracic and Endovascular Surgery at Cardiovascular Institute of the South in Lafayette, La., and the Southwest Medical Center in Lafayette, La.      Dr. Brenner is a Fellow and Past President of the American Society of Podiatric Dermatology. He is also the President of the Institute of Diabetic Foot Research, and is on the medical staff of the Long Island Jewish Medical Center in New Hyde Park, N.Y.      Dr. Karlock (shown at the right) is a Fellow of the American College of Foot and Ankle Surgeons, and practices in Austintown, Ohio. He is a Clinical Instructor of the Western Reserve Podiatric Residency Program in Youngstown, Ohio. Dr. Karlock is a member of the Editorial Advisory Board for WOUNDS, a Compendium of Clinical Research and Practice.      Dr. Zarrinmakan is a Fellow of the American College of Surgery. He practices cardiothoracic and vascular surgery in Warren, Ohio.
 

References:

1. Boykin JV, Baylis C. Homocysteine— A Stealth Mediator of Impaired Wound Healing: A Preliminary Study. WOUNDS 2006;18(4):101-116.
2. Allie DE, et. al. Critical limb ischemia: a global epidemic: a critical analysis of current treatment unmasks the clinical and economic costs of CLI. EuroIntervention Journal 2005, 1(1):75-84.
3. Dall Paola L. Treating diabetic foot ulcers with super-oxidized water. WOUNDS supplement 19(1):14-16, January 2006.
4. Allie DE, et. al. Adjunctive Bioengineered Bi-layered Cell Therapy (Apligraf®) With Excimer Laser Revascularization Improves Wound Healing and Limb Salvage in Critical Limb Ischemia. Vascular Disease Management 3(1):185-192, January/February 2006.
5. Allie DE, et. al. Novel treatment strategy for leg and sternal wound complications after coronary artery bypass graft surgery: Bioengineered Apligraf. Annals of Thoracic Surgery 72(2):673-678, 2004.