**1. Introduction**

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424 Artery Bypass

Critical limb ischemia (CLI) is the major cause of amputation in the developed world but revascularization offers an opportunity for limb salvage. Revascularization can be per‐ formed either by bypass surgery or by endovascular techniques. Peripheral bypass sur‐ gery can be performed using artificial grafts, but vein grafts offer better limb salvage and graft patency [1].

When performing revascularization of the lower limb, common clinical practice and recent guidelines include grafting of the" best vessel" which crosses the level of the ankle in order to restore pulsatile flow to the foot [1]. This may lead to either direct perfusion of the ische‐ mic area or – very often – indirect perfusion relying on collaterals surrounding the diseased zone. This strategy is different from the one used e.g. in coronary artery bypass surgery, where the aim is "complete revascularization" i.e. performing bypasses to every diseased vascular territory [2].

The arterial connections between different parts of the foot may quite often not be sufficient to ensure healing and to prevent amputation. For instance, approximately 15% of heel ulcers do not heal despite an open bypass graft to the dorsal pedal artery [3]

An alternative strategy, called the angiosome model, is based on the pioneering work of Taylor and coworkers [4], who, in the eighties, performed detailed dissections with injec‐ tion of dye in the vessels. They demonstrated the fact that the body consists of "angio‐ somes" i.e. three-dimensional blocks of tissue perfused and drained by specific arterial and venous bundles. In a later report from the same group, the angiosomes of the leg and foot were described in detail [5]

© 2013 Houlind and Christensen; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Perfusion and drainage can occur between angiosomes by means of connecting "choke" ves‐ sels, but this perfusion is less effective than direct supply from the specific feed artery of the angiosome. It is worth noting that the choke vessels are diseased in patients with diabetes and atherosclerosis. This angiosome has had profound impact on the developement of strat‐ egies for plastic and reconstructive surgery. However, only little attention has been paid to the angiosome model in treatment of critical limb ischemia. According to the angiosome model, the specific feed artery – rather than the "best vessel" – should be favoured for revas‐ cularization. The foot and ankle area consist of six angiosomes.

During the last few years, some studies have compared the results of "best vessel" ver‐ sus "angiosome" directed revascularization. The studies include comparisons of both arteri‐ al bypass and percutaneous revascularization based on the two principles

This chapter aims at describing the role of the angiosome model in critical limb ischemia, and to review the current literature.
