Raman Sharma1, Roberto Cerrud-Rodriguez2, and Prakash Krishnan1 1 Division of Cardiology, The Zena and Michael A. Weiner Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA 2 Division of Cardiology, Albert Einstein College of Medicine-Montefiore Medical Center, Bronx, NY, USA Critical limb‐threatening ischemia (CLTI) is the clinical syndrome of ischemic rest pain, ulcer, or gangrene due to ischemic peripheral arterial disease supported by hemodynamic criteria [1]. The distinction is made from acute limb ischemia, which is defined as <14 days, and takes several weeks to months [2]. Patients presenting with CLTI are classified as Rutherford Stage ≥4 or Fontaine Stage III/IV (Table 10.1). Morbidity and mortality for patients presenting with CLTI is largely determined by their elevated cardiovascular events [4–6]. One‐year risk of myocardial infarction and stroke in CLTI patients ranges from 30 to 50%, which is same risk that all peripheral arterial disease (PAD) patients are exposed to over a five‐year period [6–8]. Similarly, patients with CLTI without revascularization have a 30–50% risk of major amputation (at or above the ankle) [9]. The majority of CLTI patients can be offered an endovascular, surgical, or hybrid approach to revascularization as opposed to upfront amputation [19–11]. It is important to identify the patients who will warrant primary amputation through thorough history, physical examination with respects to paresis, ulcer/gangrene characteristics, life expectancy, and overall functionality. Classifications systems, such as the WIfI classification (Wound, Ischemia, Foot Infection), can be used to help estimate a patients one‐year risk of amputation as well as the benefit of/requirement for revascularization [12–14]. Table 10.1 Classification, staging and clinical symptoms of intermittent claudication and chronic limb‐threatening ischemia [1, 3]. For the CLTI patients undergoing revascularization, the goals of intervention can be generalized into the following [1]: The endovascular approach to revascularization for CLTI is a less invasive strategy when compared to surgical approach [15]. It should be taken into consideration that the endovascular approach is known to be less durable when compared to the surgical approach [16]. This may not, however, be a key element in the decision‐making process when considering the goal of allowing for wound healing along with the overall life expectancy of the CLTI population. In patients with better functional status, longer life expectancy, and an adequate endogenous vein for grafting, the morbidity associated with surgical revascularization may be outweighed by longer term benefits of lower reintervention rates and overall improved durability [15–17]. An early decision to make in approaching endovascular revascularization of patients presenting with CLTI is the access site. Below are the most common access sites to be used [18–20]: We recommend that initial access for revascularization should be the contralateral CFA for antegrade intervention. Alternative access should be considered with extreme iliac tortuosity, hostile groins, prior EVAR with iliac limbs, common iliac artery stents with neocarina formation, aortofemoral bypass, need for considerable support for successful crossing, and available device lengths in very tall patients. When considering ipsilateral antegrade CFA/SFA access, attention should be made to the available vessel length for the sheath (i.e. a proximal SFA lesion will make it challenging for successful delivery of sheath). Vascular complications are increased with antegrade access, particularly in obese patients [21]. Tibial access is also an option for access in CLTI intervention, when used as a sole access (transpedal arterial minimally invasive [TAMI] retrograde revascularization), or in conjunction with proximal access for lesion crossing, wire externalization, and subsequent antegrade intervention [22]. Access can be made with smaller diameter sheaths, even sheathless access, which is particularly useful when used as a means of lesion crossing and wire externalization [23]. An additional decision to make when planning tibial revascularization for CLTI is whether intervention should be limited to a single tibial artery or multiple. An important concept to mention in this debate is that of angiosomes [24]. According to the classic study by Taylor and Palmer [25] an angiosome is a three‐dimensional unit of tissue in the lower extremity, considered unique vascular territory supplied by source arteries and veins. Based on this theory, the location of the ulcer, depending on the affected angiosome (Figure 10.1), should be guide the intervention towards the single target vessel responsible for its circulation [25–28]. However, there seems to be contradictory data as in some studies, angiosome‐driven single tibial artery revascularization resulted in improvement in skin perfusion pressures with only a 50% angiosome correlation [29]. Moreover, a recent study by Kurianov et al. showed no significant difference in outcomes in patients with CTLI secondary to multilevel PAD treated with angiosome‐guided (direct, targeting the artery supplying the ischemic wound) revascularization vs. those treated with non‐angiosomic (indirect, targeting an artery supplying collaterals to the ischemic wound) revascularization [30]. Multitibial intervention has been shown to promote improved wound healing and faster healing times when compared with single tibial intervention [31]. It must be noted, however, that unaccounted confounders might exist that could potentially influence the results of these studies. Figure 10.1 Angiosomes. This figure illustrates the concept of the angiosomes as units of tissue in the foot receiving irrigation from a specific artery. Once the target vessel for intervention has been identified, one can begin the intervention. In regard to selecting the sheath, almost every tibial intervention can be successfully completed with a 6 Fr system, some through even smaller sizes. It is imperative to have adequate digital subtraction angiography images for reference or roadmap when wiring long tibial lesions, especially long CTO segments (Figure 10.2). This can be accomplished through imaging directly from the popliteal artery with a 0.035″ catheter or through the tibial vessel in question with a 0.018″ catheter (injection through a 0.014″ catheter may prove very challenging and provide poor images). Once the appropriate images have been obtained, it is important to carefully analyze the images for channels of native lumen, CTO segments, and islands of native vessel in between. If a microchannel is present, an 0.014″ hydrophilic tip wire (e.g., Command, Fielder, Fielder XT, etc.) with a 0.014″ or 0.018″ microcatheter (e.g., Teleport, TrailBlazer, etc.) can be used first. Advancing the wire, torquing frequently to avoid small collateral branches, often is quite simple when a channel is available. The catheter should be advanced over the wire to the distal tibial/pedal vessel and the wire should be exchanged for a workhorse wire that does not have a hydrophilic tip to avoid unnecessary complications (e.g., SpartaCore, Runthrough, etc.) It is good practice to take a small injection of contrast through the catheter once in the pedal circulation to confirm location within lumen, making sure to draw back blood first. Figure 10.2 Wire inside a tibial vessel. This figure demonstrates the appearance of a guidewire inside one of the tibial vessels, as seen using ultrasound. The red arrows help identify the guidewire. Once the wire has been exchanged, balloon angioplasty, preceded by atherectomy or atherotomy, should be performed. Directional atherectomy or orbital atherectomy are the most common modalities, and both are done over an 0.014″ wire. Adequate vasodilators should be administered to limit significant downstream embolization. We recommend that balloon angioplasty be performed with 1:1 balloons to avoid dissections of the vessel that would require stenting. Final DSA imaging should be taken again after vasodilator administration to demonstrate patent tibial post intervention.
10
Tibial Interventions in Patients with Critical Limb‐Threatening Ischemia
Introduction
Indications and Goals of Endovascular Revascularization
Symptom
Rutherford classification
Fontaine classification
Intermittent claudication
Asymptomatic
Stage 0
Stage I
Mild claudication
Stage 1
Stage IIA (Symptoms after >200 m)
Moderate claudication
Stage 2
Stage IIB (Symptoms before <200 m)
Severe claudication
Stage 3
Critical limb‐threatening ischemia
Ischemic rest pain
Stage 4
Stage III
Minor ulceration
Stage 5
Stage IV
Major ulceration or gangrene
Stage 6
Considerations for Access Site
Single Versus Multitibial Artery Revascularization
Antegrade Tibial Artery Intervention
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
