**6. Results from direct versus indirect revascularization**

**5. Imaging and assessment**

A fundamental prerequisite of providing angiosome-directed revascularization is pro‐ found knowledge of the anatomy of the pedal vasculature as well as adequate imaging technique including intraprocedural angiography of both tibial and pedal arteries. Manzi and coworkers have recently reported their experience from more than 2500 antegrade interventional procedures in patients with critical limb ischemia and diabetes [10]. For imaging of the pedal arteries they stress that prolonged filming is often necessary to re‐ cord delayed enhancement of of pedal vessels from retrograde or collateral circulation and that both standard anteroposterior and lateral oblique projections should be ob‐ tained. They have established the following two criteria for correct positioning of the im‐ age intensifier: 1) The base of the fifth metatarsal bone must be seen to project outward from the base of the foot in the lateral oblique view and 2) the first proximal metatarsal interspace must be clearly visualized in the anteroposterior view. These two views tend

Attinger and coworkers have described in detail how to map the arterial-arterial connec‐

As an example, the Doppler signal is located from the posterior tibial artery over the tar‐ sal tunnel. If the signal persists when occluding (by digital compression) the artery dis‐ tally, there is antegrade flow along the posterior tibila artery. If the signal disappears, the flow is retrograde from the anterior tibial artery via the dorsalis pedis and lateral plantar arteries. Similarly, Doppler signal can be obtained from the anterior perforating branch of the peroneal artery in the lateral soft area between the tibia and fibula just above the ankle joint. When the anterior tibial artery is occluded at the takeoff of the lat‐ eral malleolar branch, the Doppler signal will persist if there is antegrade flow along the anterior perforating branch of the peroneal artery. If the Doppler signal disappears, fill‐ ing of the anterior perforating branch must be retrograde from the anterior tibial artery through the lateral malleolar branch. The authors describe how the competence of these connections can have profound significance for the healing potential of an amputation

Nagase and coworkers [11] reported the results of plantar thermography of skin tempera‐ ture in 129 non-ulcer diabetic patients and 32 normal volunteers. From the pattern of four different plantar angiosomes originally described by Attinger [7], they defined twenty dif‐ ferent patterns of temperature distribution. The most common pattern in normal subjects was a "bilateral butterfly pattern" in which the medial arch showed the highest temperature (46.9%) or an even distribution of temperature across the entire planta of the feet (20.3%).

to give a good overview of the pedal arteries and collaterals.

**5.1. Angiography**

430 Artery Bypass

**5.2. Doppler ultrasound**

wound.

**5.3. Thermography**

tions using a Doppler device [7].

A number of studies have been performed comparing the results of direct revascularization to the relevant angiosome with those of indirect revascularization either through collaterals or choke vessels.

In 2009, Neville and coworkers published a retrospective analysis of 43 patients undergoing bypass surgery for tissue loss due to ischemia [12]. Twenty-two were directly revascularized to the relevant agniosome while 21 were indirectly revascularized. Healing occurred in 91% of the directly revascularized patients and only 62% of the indirectly revascularized patients (p=0.03]. Major patient characteristics such as diabetes, tobacco use, and renal failure were evenly distributed between the directly revascularized and indirectly revascularized groups, but wound characteristics and infection were not reported.

On the other hand, Azuma and coworkers [13] reviewed the results of 249 consecutive distal bypasses for critical limb ischemia. 218 limbs were included in the initial analysis which proved significantly lower wound healing rate in the indirect revascularization group than in the direct revascularization group. This was especially the case in a subgroup of patients with end stage renal failure. This finding was, however, compromised by significant base‐ line differences between the groups especially characterized by a higher proportion of pa‐ tients with heel ulcers and gangraene in the indirect revascularization group. After applying propensity scored analysis including only 48 pairs of limbs, the healing rate between the two groups did not reach statistical significance (p=0.185). The authors concluded that the angiosome concept was not relevant for open surgical treatment of critical limb ischemia in patients without end stage renal failure. This conclusion may be questioned in view of the limited statistical strength of the propensity scored analysis.

Iida and coworkers reviewed the results of endovascular treatment of 203 limbs in 177 con‐ secutive patients with critical limb ischemia, Rutherford 5 or 6 [14]. During up to 4 years fol‐ low up, they found significantly higher limb salvage rate in patients with the directly revascularized than indirectly revascularized wounds. Interestingly, the total number of ti‐ bial vessels with run off did not influence the limb salvage rate in neither group, indicating that it is not important how much blood can be provided to the foot but rather whether i t reaches the ischemic area. In a later review by the same group [15], including 369 limbs from 329 consecutive patients, including only patients with isolated below-the-knee lesions, pa‐ tients who had received direct revascularization experienced significantly higher levels of amputation-free survival and freedom from major adverse limb events than patients in whom only indirect revascularization was possible. In this review the finding was con‐ firmed after propensity matching of groups. In multivariate analysis, elevated levels of c-re‐ active protein were found to be independent predictors of major amputation in the indirect revascularization group but not in the direct revascularization group. This may imply that indirect revascularization may be inadequate for the healing of infected wounds.

calf vein followed by selective embolization of collaterals, directing arterial blood to the rele‐ vant venosome. Using this strategy, a 73% three year limb salvage rate was achieved [24].

The Role of The Angiosome Model in Treatment of Critical Limb Ischemia

http://dx.doi.org/10.5772/54418

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The concept of angiosome-directed revascularization is, theoretically, attractive and in ac‐ cordance with pathophysiological knowledge. It is also in line with experience from coro‐ nary bypass surgery, where reperfusion through collaterals does not provide a similar freedom from cardiac events as that provided by complete direct revascularization of all the

It is well established that healing of an ishemic pedal wound is more effectively ach‐ ieved when pulsatile arterial blood flow is established across the ankle and it seems logi‐ cal to expect that this effect is larger when the pulsatile flow is provided all the way to

As suggested by the above mentioned papers, the effect of direct revascularization may es‐ pecially be relevant in the settings of end stage renal failure, infected wounds, endovascular

The angiosome concept represents a novel approach to improving the therapy of critical limb ischemia. It may potentially provide the rationale not only for the choice of target ar‐ tery. It may also influence the indications for endovascular or open repair according to

Although the evidence in favour of an angiosome directed treatment is mounting fast, it is, however, still circumstantial. All of the studies comparing the results of direct and indirect revascularization are retrospective and, thus, biased by heterogeneity in patient selection. More often than not, the angiosome specific artery will also be the most diseased artery and the ability to recanalize this vessel will most probably select the least atherosclerotic patients to the "direct revascularization" group. It is also likely that the advocates of an angiosomedirected revascularization strategy would attempt direct revascularization first and only perform indirect revascularization if this attempt was unsuccessful. Regardless of any retro‐ spective matching of the groups this would lead to patients with extensive distal atheroscle‐ rosis to be placed in the indirect revascularization groups, thus biasing the comparisons in favour of the angiosome specific approach. The differences in healing rate and limb salvage between groups may, therefore, merely reflect preoperative differences in the extent of oc‐ clusive disease. It is possible that this is what is reflected in the lack of statistically signifi‐

As highlighted in the study by Varela, the presence or absence of collaterals merit further investigation [22]. For this purpose, the Doppler method described by Attinger [7] seems to

As evidence stands at the moment, there is some, although limited, evidence that when there is a choice of target artery for revascularization, preference should be given to the ar‐

rather than surgical repair, and in cases where collaterals are absent.

cant differences after propensity scoring in the study by Azuma [13].

which target artery is accessible by which method.

be a good and non-invasive technique.

**7. Discussion**

diseased vascular territoria [2].

the site of the injury.

Alexandriescu and collegues have published several reports describing their experience with targeted primary angioplasty of diabetic foot lesions [16-17]. In a series of 124 limbs (98 patients), they were able to achieve direct revascularization in 82% [16]. Limb salvage was 91% at 12 months and 84% at three years follow-up. More recently, they published a histori‐ cal comparison between their results before and after 2005 when they introduced the angio‐ some concept in their practice. Despite similar graft patency and technical success, they experienced a significantly better wound healing rate and limb preservation in the group of patients treated according to the angiosome concept [18]. This result is interesting although it is probably biased by the general learning curve of the group.

In a paper published together with Alexandriescu, the vascular surgery department at the University Hospital in Helsinki, Finland recently reported their results from the last three years [19]. In a population including approximately the same number of direct and indirect endovascular revascularizations, they found 74% of the wounds to have healed within one year in the directly revascularized group compared to 46% in the indirectly revascularizd group (p=0.002). The number of patients was, however, not reported.

Two studies, one surgical by Deguchi [20] and one endovascular by Blanes Ortí [21] failed to show any difference in wound healing time or limb salvage between directly or indirectly revascularized patients. Due to small numbers, the statistical strengh of these comparisons is, however, limited.

#### **6.1. The influence of collaterals**

The prognostic significance of indirect revascularization via collaterals was studied by Vare‐ la in a mixed cohort of venous bypass and endovascular treated patients with ischemic wounds [22]. Defining collaterals visible on perioperative angiograms, either between distal calcaneal peroneal branches and anterior or posterior tibial artery (n=16) or patent pedal arch connecting dorsal and plantar blood supply (n=2), they found a similar wound healing rate for indirect revascularization of the wound area through collaterals as for direct revas‐ cularization to the angiosome specific feed artery (92% versus 88% wound healing at 12 months follow-up). When including indirect revascularizations without visible collaterals, only 73% of the wounds had healed after 12 months (p=0.008).

#### **6.2. The significance of venosomes**

Anatomically, the venous drainage follows the arterial perfusion of the angiosomes [23] and Alexandriescu used the term venosome, when reporting the results of surgical deep calf vein arterialization. In a series of 26 limbs in 25 diabetic patients with very advanced below the knee occlusive disease, a PTFE bypass was made between an arterial inflow and a deep calf vein followed by selective embolization of collaterals, directing arterial blood to the rele‐ vant venosome. Using this strategy, a 73% three year limb salvage rate was achieved [24].
