Angiosome concept in the treatment of critical limb ischaemia

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The role of angiosome-targeted revascularisation has been under research in Helsinki University Hospital since 2010. The areas of interest have been the feasibility of angiosome targeted revascularisation as well as its importance in wound healing and leg salvage. In feasibility studies, the question to be answered has been in how many cases is it possible to choose angiosome-targeted bypass, and in how many cases is the wound spread over several angiosomes? In one third of cases there is only one option for the revascularisation. Surprisingly, only in one quarter of the patients undergoing revascularisation due to critical limb ischaemia and tissue lesion, the wound is located in only one angiosome. Ultimately, angiosome-targeted revascularisation is possible in 80% of cases.

In a series of 769 patients, including both diabetic and non-diabetic patients, who underwent surgical bypass or endovascular revascularisation due to severe limb ischaemia and tissue lesion, the best wound healing was achieved after angiosome-targeted bypass followed by non-angiosome-targeted bypass surgery and angiosome-targeted endovascular revascularisation. It was obvious that wound healing was significantly faster after surgical bypass compared with endovascular revascularisation. There was no difference in leg salvage rate between surgical and endovascular revascularisation if the procedures were angiosome-targeted. The worst leg salvage was seen after non-angiosome-targeted endovascular revascularisation.

In a recent series of 545 diabetic patients the findings were clear: after surgical bypass, there was no significant difference in wound healing or leg salvage between angiosome-targeted and non-targeted-procedures. However, after endovascular revascularisation, both outcome measures were significantly worse after non-targeted procedures than after targeted ones. Again, there was no significant difference between endovascular and surgical treatment if the endovascular treatment was angiosome-targeted.

In addition to the retrospective studies, we are at last gathering some evidence from a prospective trial. The ongoing study gives haemodynamic evidence to the angiosome concept. So far, 72 patients who underwent either surgical bypass or endovascular revascularisation due to severe limb ischaemia have been examined prospectively including photography of the foot lesion, angiograms allowing detailed information on collaterals, data on wound healing during the follow-up as well as indocyanine green fluorescence imaging (ICG-FI) measuring foot perfusion in each angiosome. The preliminary results are in line with the retrospective studies; ICG-FI shows a significantly higher increase in perfusion after revascularisation in the angiosomes which were revascularised directly than in the angiosomes that were revascularised indirectly, although this difference in perfusion increase between directly and non-directly revascularised angiosome was seen only in patients who underwent endovascular treatment. After surgical bypass almost no difference in perfusion using ICG-FI measurements was seen between directly and indirectly revascularised angiosomes. The meaning of collateral circulation was also clear; if there were good collaterals between the angiosomes, the increase in the indirectly revascularised angiosome was also significant regardless of the method.

Maarit Venermo, Helsinki University Central Hospital, Helsinki, Finland