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

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

   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.

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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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