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

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.

   I made an immediate referral to an interventional cardiologist, who performed an arteriogram as an in-patient procedure within 24 hours of my initial evaluation.
Occlusions at the dorsalis pedis and posterior tibial arteries were present. The interventional cardiologist attempted to open both vessels but reperfusion was only successful at the dorsalis pedis. The posterior tibial artery was calcified beyond repair.

   Further ischemic changes occurred at the three medial toes. At that point, the foot was considerably warmer and capillary refill occurred at the lateral fourth and fifth toes. We obtained Doppler pulses at the dorsalis pedis but not at the posterior tibial artery. We recommended a transmetatarsal amputation as a limb preservation option and the patient consented.

   Intraoperatively, the case could not have gone any better. The patient had excellent perfusion and anatomically, the foot had no deformities from prior diabetes-related infections, degenerative or iatrogenic causes. The total time from start to finish of the procedure was approximately 30 minutes. The patient did well in the immediate 48 hours postoperatively and seemed to be heading toward an uneventful recovery until approximately the fifth day after the procedure.

   At that point, a distinct color change occurred along the plantar distal medial aspect of the foot. This deteriorated over the next week as sloughing of the skin, further demarcation and eschar formation occurred and intensified.

   The knowledge that the posterior tibial artery could not be opened, coupled with the extent of further ischemic changes along the posterior tibial angiosome, helped lead to the decision to recommend the patient for a below-knee amputation. This occurred approximately three weeks after the initial transmetatarsal amputation. Postoperatively, after the below-knee amputation, the patient’s condition deteriorated and he subsequently died less than three months after presenting with discoloration of his toes.

In Conclusion

This case illustrates that even though a targeted angiosome-directed approach to revascularization appears to be validated by preliminary evidence, sometimes even the best-laid plans are unsuccessful. The degree and extent of calcification of lower extremity arteries is still the final factor as to whether one can successfully open an occluded artery and preserve an ischemic lower extremity.

   An understanding of angiosomes, as well as some of the emerging interventional procedures that compliment surgical lower extremity bypass, can 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 determining which salvage cases are more likely to fail.

   Subjecting patients to multiple digital and foot amputations, that in hindsight turn out to be futile, is taxing on patients, providers and even the healthcare system. Increasing the odds for success through the utilization of angiosomes and targeted revascularization is likely to prove an important next step in the evolution of lower extremity preservation.

   Dr. Bell is a board certified wound specialist of the American Academy of Wound Management and a Fellow of the American College of Certified Wound Specialists. He is the founder of the “Save a Leg, Save a Life” Foundation, a multidisciplinary, non-profit organization dedicated to the reduction of lower extremity amputations and improving wound healing outcomes through evidence-based methodology and community outreach.

References
1. Taylor GI, Palmer JH. The vascular territories (angiosomes) of the body: experimental study and clinical applications. Br J Plast Surg 1987; 40(2): 113-141.
2. Singh K. New treatment paradigm: the angiosome concept. Pod Today. 2012; 25(Suppl2):4-7.
3. Neville RF, Attinger CE, Bullan EJ, et al. Revascularization of a specific angiosome for limb salvage: does the target artery matter? Ann Vasc Surg. 2009; 23(3):367-373.
4. Iida O, Soga Y, Hirano K, et al. Long-term results of direct and indirect endovascular revascularization based on the angiosome concept in patients with critical limb ischemia presenting with isolated below-the-knee lesions. J Vasc Surg. 2012; 55(2):363-370.