How to Approach the “Desert Foot” in the CLI Patient

Introduction

J.A. Mustapha, MD

Critical limb ischemia (CLI) remains a mysterious disease and it is difficult to pinpoint a universal definition to describe its aggressive nature. Clinically, many of us may refer to a patient as having CLI if they present with rest pain and in the same breath, we may refer to a patient as having CLI if they present with black foot. Clearly, there is a broad spectrum of presentation and unfortunately a narrow description of it. The same broad spectrum also exists in the invasive nature of CLI. A patient with rest pain and single-vessel runoff will be defined as CLI just as much as a patient with rest pain and/or skin breakdown with absent flow to the foot, usually referred to as desert foot. Patients with CLI and desert foot tend to land on the spectrum of a no-option patient more often than required.  In this issue, Dr. Luis Mariano Palena will be sharing with us the most current available options for patients with desert foot.

J.A. Mustapha, MD: What is your angiographic definition of desert foot?

Luis Mariano Palena, MD: Desert foot is an infrequent vascular condition that affects diabetic patients with CLI and frequently those with chronic renal failure and hemodialysis. This condition is defined as “the occlusion of all the main foot arteries”. It means occlusion of the dorsalis pedis, lateral tarsal artery, both plantar arteries, and occlusion of the plantar arch. The angiography only shows collateral vessels of the foot.

Dr. Mustapha: Considering the significant lack of target vessels in the foot, what was the driving factor for you to venture into creating treatment options for these patients?

Dr. Palena: These patients often arrive to our care with ischemic and infected ulcers in the foot. Due to their baseline vacular conditions, they are at high risk for major amputation. On the other hand, these patients are poor candidates for distal bypass or for any surgical revascularization, because of the lack of flow through any of the main vessels in the foot. For these reasons, these patients do not have anything to lose and allow us to try, sometimes in an aggressive way, to save their limbs.

Dr. Mustapha: What is your current clinical and invasive assessment strategy for a patient with desert foot?

Dr. Palena: All these patients arrive at our cath lab with a precise clinical indication. Complete assessment of the ulcers (presence of ischemia and/or infection) and assessment of the deepness of the ulcer (involvement of the soft tissue, the bone, etc.) is usually done using the Texas University Classification (TUC). The invasive assessment includes selective and super-selective angiography.  Two-dimensional perfusion imaging is used when trying to understand if we can improve perfusion of the foot when treating the proximal vessels.

Dr. Mustapha: Do non-invasive hemodynamics play a role throughout the course of therapy?

Dr. Palena: The only non-invasive hemodynanic measure we use is the transcutaneous oxygen value (TcPO2) that demonstrates the presence of ischemia, but does not show us the desert foot condition. I believe it is very difficult for these patients to achieve any clinical improvement without revascularization.

Dr. Mustapha: Do you have guidelines in your institution to define which patients will require primary major amputations? Or do all of your patients get at least an attempt at revascularization?

Dr. Palena: Primary major amputation is indicated in patients with deep infections that involve not only the foot bones, but also the tibial and fibular bones, without any possibility to save the leg where revascularization could increase the risk for septicemia, as related to the presence of the infection. Clearly, this situation is very infrequent. 

If the patient does not meet this clinical scenario, in all other cases, we believe in bringing these patients for at least an attempt at revascularization, with the aim of saving and maintaining a functional limb.

Dr. Mustapha: What is the average time required for you and your team to revascularize a desert foot?

Dr. Palena: It depends patient by patient. However, as a good rule, we try to not work more than 2 hours, which is often enough time to successfully treat complex multilevel and multivessel arterial disease. 

Dr. Mustapha: Please share a case with us.

Dr. Palena: I will describe a case of desert foot in a diabetic patient with CLI. You can see he was in Rutherford class 6 (Figure 1) and there were not any patent main vessels on the foot (Figure 2). After subintimal recanalization of the dorsal and plantar circulation, including the plantar arch, we were able to restore the blood flow to the foot, achieving a complete foot recanalization (Figure 3). The patient underwent transmetatarsal amputation that healed and was maintained for 3 years (Figure 4).

Dr. Mustapha: Do patients with desert foot receive additional follow-up in comparison to patients without desert foot?

Dr. Palena: No specific follow-up. Our idea is to obtain an ulcer or surgical incision healing and we always regularly follow up with those patients in trying to achieve this goal.

Dr. Mustapha: What is your medical cocktail for CLI patients with desert foot after revascularization? 

Dr. Palena: It is the same as for all patients with CLI: dual antiplatelet therapy for 3 months and then aspirin for life. 

Dr. Mustapha: Do you feel more operators will be able to perform similar procedures with the proper training? 

Dr. Palena:  I truly believe so. I think that actually many operators are able and are increasing the necessary skills to successfully treat this kind of situation. The learning curve is, in my opinion, the same that every vascular specialist undergoes to treat the foot vessels in CLI patients. This means every vascular specialist dedicated to CLI treatment should be able to treat this complex and extreme situation.

Dr. Mustapha: Do you see CLI becoming its own specialty, with a team-focused approach to achieve the highest safety and efficacy?

Dr. Palena: In the near feature, I think we will have greater dispersion of this concept. Actually, in Italy as well as in many other countries, there are dedicated CLI centers that work in a multidisciplinary way. I hope this concept will spread to achieve safe and efficient treatment.

Dr. Mustapha: What is your advice to global operators who are willing to take on desert foot revascularization?

Dr. Palena: My advice, if I can give it, is to always try to recanalize the foot arteries of those patients affected by desert foot, following the clinical indications and considering that these patients do not have anything to lose. 

Dr. J.A. Mustapha can be contacted at jihad.mustapha@metrogr.org. Dr. Luis Mariano Palena can be contacted at marianopalena@hotmail.com. Dr. Palena reports no relevant conflicts of interest regarding the content herein.