Can Angiosome-Based Revascularization Have An Impact In Limb Salvage?

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Author(s): 
Desmond Bell, DPM, CWS, FACCWS

This author details the case of a 71-year-old patient who had reperfusion procedures for occlusions at the dorsalis pedis and posterior tibial arteries, and subsequently had transmetatarsal and below-knee amputations.

The advent of endovascular procedures, coupled with surgical bypass of the lower extremities and advances in wound healing technologies, has helped to enhance the importance of the team approach to limb preservation.

   Identifying occluded arteries in the lower extremity and subsequently being able to open them to restore blood flow where gangrene was impending has preserved an ever-increasing number of legs that previously may have been doomed to amputation. Endovascular procedures have concomitantly extended the duration of life and improved the quality of life for many.

   Taylor and Palmer introduced the concept of angiosomes.1 Conceptually analogous to neurological dermatomes, angiosomes provide a vascular mapping of the body, showing anatomical regions between the skin and bones that are supplied by specific arteries and veins.

   Angiosome-based revascularization is the concept in which the target artery for reperfusion is the one associated with the ischemic angiosome. This direct revascularization approach is associated with higher limb-salvage rates than indirect revascularization, in which a non-angiosome vessel is the target.2

   In independent retrospective analyses, Neville, Iida and their respective colleagues found that utilizing targeted direct angiosome revascularization resulted in significantly fewer amputations.2-4 These authors noted this also led to a higher amputation-free survival rate in comparison to non-angiosome guided indirect revascularization.2-4

   Despite the best efforts of the treating clinicians, the following case did not have a good outcome. It does however provide a clinical application of the value of angiosomes and the importance of targeting arterial occlusion when considering revascularization.

When Attempted Reperfusion Fails In A 71-Year-Old Patient

A 71-year-old male presented with an approximately 25-year history of diabetes. After several years of intermittent treatment for right foot ulcers and osteomyelitis of his fifth metatarsal, the patient had been living uneventfully without any further foot ulcers or issues for nearly two years.

   The patient called for an appointment with a new concern of “new wounds on his foot.” Upon expedited evaluation in my office, I discovered that the patient had ischemic changes to his left foot, specifically the medial three toes and forefoot that were consistent with critical limb ischemia.

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Jeff Mennutisays: March 2, 2012 at 1:26 pm

I have had many consults regarding this same scenario. In my humble opinion, a majority of flow to the foot occurs via the posterior arteries. I would not have proceeded to TMA. Amputation should have been done at the level of occlusion. Flow only to the anterior portion of the foot would give mild viability of skin to dorsum of the foot, not enough to salvage a TMA. Perhaps a bypass should have been considered. Hopefully, nothing becomes of this.

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Desmond Bellsays: March 17, 2012 at 3:57 pm

Hi Jeff,

I appreciate your comments regarding this unfortunate patient.

First, I agree 100% with your assessment regarding the posterior tibial artery. Whether it be a heel ulcer or a plantar foot ulcer, if the PTA is occluded, the odds of a good clinical outcome decrease, whether it be healing of a wound or a surgical procedure. Not only is this point accurate purely from an intuitive understanding of the anatomy but an article by Guzman, Brinkley, et al discussed this. (See Guzman, Brinkley, et al. Tibial artery calcification as a marker of amputation risk in patients with PAD" J Am Coll Cardiol 2008;51(20):1967-1974.

In this case, the patient was NOT a bypass candidate. That had already been ruled out.
I presented this case more for the scenario that can happen when we are the ones left holding the "hot potato".

The patient underwent partially successful endovascular intervention below the knee with the DP being opened but attempt to open the PT was not successful. So to your point, he did have blood flow to the forefoot, albeit not from the posterior tibial artery.

Anyone who has performed limb preservation surgery during their career would probably agree that sometimes despite our best attempts, things may not work as we hope. In this case, options were presented to the patient and his family, including a below-knee amputation. The decision to attempt a TMA was based on further consultation with the endovascular specialist, who also recommended a TMA, in addition to the wishes of the patient.

Even though we knew going in that the PT remained occluded, our hope was that enough collateralization off the PT had occurred that would assist in supplying adequate blood flow to supplement the patent DP and peroneal arteries. The idea of a 50-50 chance of a successful TMA seemed worth the attempt versus the 0% chance the patient would have of walking on his own foot and leg that a BK amputation offered.

Again, the patient's surgery was technically beyond expectations as was his intraoperative perfusion. His foot remained warm for several days post-op until the plantar blanching became more evident.

I know there have been a number of cases I have performed where I was far less optimistic of a good outcome and yet the patients healed.

I felt that sharing this case was a great clinical illustration of the angiosome concept. An understanding of angiosomes, as well as some of the emerging interventional procedures that compliment surgical lower extremity bypass, can potentially improve critical limb ischemia outcomes. Not only can the clinical application of the concept result in better outcomes but conversely, it may provide greater prognostic value in identifying critical limb ischemia cases that have an increased likelihood of failure where limb salvage surgery, such as amputation of a toe, partial forefoot amputation or even serial debridement, is being considered or attempted.

Thanks again for taking time to comment on the article.
Best regards,
Des

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