Technical Aspects of BTK Interventions

Once the CLI is retained based on clinical ground and the non-invasive arterial evaluation, usually an endovascular approach has to be preferred compared to the more aggressive surgical options. Usually an antegrad approach of the ipsilateral common femoral artery should be preferred because of a better pushability and torqueability of the material using this approach and the possibilty to reach also very distal lesion in case of necessity (i.e. below the ankle interventions).

The exact vascular anatomy, as well as the exact disease extension should be obtained with a selective injection directly in the distal segment of the popliteal artery, and at that moment the best revascularization strategy should be planned. Due to the frequency of the presence of a multivessel and multilevel disease, the intial revascularization strategy should be carefully evaluated, because it is often not possible to completely revascularize all the three diseased vessels. The aim of every BTK revascularization attempt is to restore a pulsatile direct flow to the foot and preferentially to the part of the foot presenting the ischemlic ulcer. This angiosome concept (see below) is of paramount

importance because in order to give all the chances to an ulcer to heal it is mandatory to reopen the target vessel perfusing the diseased part of the foot (270, 271). Accordingly, it seems not reasonable to treat an easier to treat vessel, which is not targeting the ulcer and leave the completely occluded target vessel untreated.

Furthermore, it is also of capital importance to assure a sufficient distal foot perfusion and not to establish a perfect three vessels recanalization just to the ankle and leave the below the ankle foot perfusion untreated. This is essential in order to improve ulcer healing as well as to improve BTK vessel patency, because the BTK vessel reocclusion rate is increased in case of a bad distal foot runoff (272).

Once revascularized at least one BTK vessel straight down to the foot, it is mandatory that this unique vessel remains patent sufficiently long, in order to allow the ulcer to heal. Accordingly, in case of a single vessel runoff, the use of more expensive devices, assuring a better longterm patency

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seems reasonable (e.g., DES or DEB), as well as the attempt of more complex thus more risky, revascularization techniques.

6.6.2.1 The trans-collateral approach: (Figure 49):

This technique, very similar to that used for the coronary retrograde recanalization approach, is aimed to better visualize the entry zone of the occluded vessel. The retrograde wire will give a better target for the antegrad wiring (i.e. “kissing wire technique”), which may safely and more rapidily be performed also using dedicated, thus more aggressive, recanalization wires. Furthermore, in case of antegrade wiring failure, the retrograde wire may be also used as the primary recanalization wire, creating a microchannel from retrograde, thus facilitating the balloon passage and the entire revascularization procedure. The most developed collateral branch has to be preferred, because through this collateral it might be necessary to advance different type of microcatheters of balloon catheters (273, 274).

Figure 49: Trans-collateral approach to recanalize an occluded posterior tibial artery (ATP) through a collateral arising from the peroneal artery (AP)

Black arrow = sub-intimal antegrade wire - White arrow = PTA through the collateral [reproduced from Bonvini RF et al. (238)]

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6.6.2.2 The retrograde approach via the direct puncture at the foot level: (Figure 50):

This technique, similarly to that of the trans-collateral approach, facilitates the connection between both patent segments proximally and distally the occlusion. This retrograde approach should only be used in case of a failed previous antegrade attempt (275). The rational of using this approach is that often the retrograde intraluminal recanalization is more easily obtained than that performed antegradely which relatively often turn in a sub-intimal recanalization failure. Indeed, once the vascular access is obtained at the level of the foot, the intra-luminal connexion is secured and than the chance of failure decreases significantly (276, 277).

Usually the ATP or the pedal artery in the distal ATA’s segment at the level of the ankle should be used, because at this level these arteries are easier to puncture and especially are easy to compress obtaining adequate hemostasis. However, in case of necessity, the direct puncture of the peroneal artery may be attempted, with special considerations at the end of the procedure while attempting hemostasis (i.e. blood pressure cuff at site of puncture and rigours local and hemodynalmic surveillance during the first six hours post-procedure).

Figure 50: posterior tibial artery (ATP) puncture for a retrograde ATP recanalization White arrow = micro-needle puncturing the distal ATP; APL = plantar artery;

Black arrow = wire and balloon directly inserted through the foot skin [reproduced from Bonvini RF et al. (238)]

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6.6.2.3 The pedal-plantar loop technique: (Figure 51):

As mentioned above, this technique may be very useful in order to increase the foot perfusion when the disease is extending the below the ankle region and there is the impossibility to reopen the occluded vessel targeting the ischemic lesion. Accordingly, the plantar arch is dilatated up to the contralateral vessel, in order that the single open vessel arriving to the foot is able to perfuse, thanks to an improved plantar arch, also the contralateral part of the foot (278). This re-established loop between the plantar arch and the pedal artery should allow a better fingers perfusion, thus finally improving ulcer’s healing process (279, 280).

Figure 51: plantar arch angioplasty through the dorsalis pedis artery (ADP) in order to improve the plantar artery perfusion (APL)

White arrows = sub-occlusion before and after angioplasty [reproduced from Bonvini RF et al. (238)]

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