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John H. Rundback, MD, FAHA, FSVM, FSIR, Kevin Chaim Herman, MDFrom the Holy Name Medical Center, Interventional Institute, Teaneck, New Jersey.

Transpedal Interventions for Critical Limb Ischemia

ABSTRACT: There is a growing prevalence of critical limb ischemia (CLI) with resulting complex patterns of tibial occlusive disease that represent unique challenges for interventionalists. Because patients with CLI have sub-stantial comorbidity, endovascular therapy has emerged as the primary therapy in many cases, requiring novel and advanced techniques to achieve technical and clinical success. Standard techniques for crossing obstructive lesions fail in a substantial percentage of patients with CLI due to the presence of extensive arterial calcification and long-segment occlusions. Retrograde recanalization via fluoroscopic or ultrasound-guided puncture of recon-stituted pedal vessels may allow lesion traversal in difficult cases, allowing primary retrograde revascularization or rendezvous techniques with subsequent antegrade intervention. This paper describes the rationale, techniques, and outcomes of transpedal interventions in patients with CLI.

VASCULAR DISEASE MANAGEMENT 2013:10(8):E152-E158 Key words: peripheral vascular disease, critical limb ischemia, endovascular therapy

Critical limb ischemia (CLI) rep-resents the most advanced form of peripheral arterial occlusive

disease (PAOD), manifested by pain at rest, focal or diffuse foot and ankle ulcer-ations, or gangrene. The rate of PAOD progression to CLI may approach 25%,1

and these patients have a particularly poor prognosis. For patients with CLI, the natural clinical course over 1 year from the time of diagnosis has been estimated to follow the “rule of quar-ters,” with approximately one-quarter resolving, one-quarter having persistent CLI and ulceration, one-quarter hav-ing undergone major amputation, and one-quarter died.2,3 Following amputa-tion, nearly half of patients die within 1 year, and half of survivors never ambu-late.4 These factors, combined with an epidemic increased prevalence of pro-gression to CLI in elderly, diabetic, and chronic kidney disease patients, make CLI a sizeable and increasing burden on

the healthcare system.5,6

Historically, surgical7-9 and endovas-cular10-15 therapy for CLI have enabled approximately 80% “limb salvage.” De-spite recognized risk factors, nearly 80% of patients who undergo major amputation fail to see a vascular spe-cialist or undergo a vascular evaluation for potentially remediable disease.16,17

Referrals for possible revasculariza-tion are often late, with resultant pat-terns of disease that are often challeng-ing for reconstruction. Notably, in this population, there is a high proportion of long-segment and multivessel tibial occlusion, a paucity of well-formed col-laterals, dense calcification, and poorly delineated pedal outflow channels. Consequently, traditional methods of antegrade recanalization fail in a high percentage of cases.18

Combined retrograde and antegrade interventions have historical precedent for femoropopliteal revascularization

using the initially described “Bolia” technique.19 In these cases, the recana-lized channel may be either intralumi-nal or subintimal, with eventual cap-ture or snare retrieval of a retrogradely passed wire into an antegrade catheter, allowing wire rendezvous and subse-quent antegrade intervention. Recent work by others20-25 has demonstrated the ability to extend these “rendezvous” techniques to patients with complex patterns of tibial occlusive disease that either fail or are not amenable to other strategies.

PATIENT SELECTIONTranspedal revascularization may be

used as either a primary or secondary strategy (Figure 1). More commonly, a secondary transpedal approach is utilized, after failed recanalization of occluded tibial segments using tradi-tional or advanced antegrade catheter techniques. These patients typically

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have extensive calcification and long-segment arterial obstructions prevent-ing successful intraluminal wire passage despite best attempts. This difficulty is compounded by the dense fibrocalcific nature of the proximal occlusive cap and the presence of numerous mar-ginal collaterals at the occlusion mar-gin through which wires preferentially direct. Due to the absence of dedicated distal tibial re-entry devices, if a sub-intimal path is created, spontaneous reentry into distal targets is required for interventional success. In our ex-perience, this can be challenging, with inline flow restored to the foot in ap-proximately 60% of subintimal cases; success rates are even lower when re-canalizing an occluded posterior tibial artery due to difficulty advancing wires around the medial malleolus. In these instances, angiographically demon-strated patent distal calf or pedal arter-ies may be accessed directly with the goal of performing retrograde tibial recanalization.

Primary transpedal revasculariza-tion represents a novel interventional strategy for patients with unfavor-able anatomy and an anticipated low likelihood of success using traditional techniques. In addition, a primary transpedal route may have benefit in allowing intraluminal revasculariza-tion if this is desired, such as when planning the use of drug-eluting bal-loons for treatment: due to the ab-sence of marginal collaterals and a fibrous cap when passing wires crani-ally, maintaining a wire position with-in the true lumen may be facilitated.

More recently, an intentional first-line transpedal approach has been ad-vocated by Mustapha,23 citing an abili-

Table 1. Tools used for transpedal-tibial interventions.

Device Characteristics Manufacturer

Wires

Hydro-ST 0.014, stainless steel hydrophilic, good support

Cook

Command 0.014, stainless steel, shapeable tip Abbott

Roadrunner 0.035, nitinol core, hydrophilic, 1:1 torque Cook

CTO-12 and CTO-18

0.014, stainless steel mandril with shorter taper provides good pushability and pen-

etration

Cook

Regalia XS 0.014, floppy shapeable tip, moderate sup-port

Asahi

Platinum Plus 0.014 or 0.018, hydrophilic, stainless steel with good pushability and excellent support

Boston Scientific

Microcatheters

CXI Flexible braided catheters with hydrophilic coating provides good support for crossing

difficult lesions

Cook

Quick-Cross Hydrophilic coating with stainless steel braiding good for smooth tracking.

Spectranetics

Renegade STC Vortec fiber and stainless steel braid helps in smooth tracking

Boston Scientific

Figure 1. Decision-making algorithm for transpedal arterial interventions.

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ty to easily access the pedal vessels with ultrasound guidance, and describing treatment of both the anterior tibial and posterior tibial branches via a dor-salis pedis puncture. The rapid adoption of dissemination of these techniques

will be enabled by the development of dedicated devices and training path-ways, similar to what has evolved for transradial catheterization.26

TOOLSTranspedal revascularization is com-

plex and time consuming. There are several key tools that interventionalists must be familiar with and have available in order to achieve successful revascu-larization. Prior to embarking on this

journey one must allot the appropriate amount of time for the procedure; of-ten, a second interventionalist may be needed for portions of the procedure.

Transpedal access generally requires a handheld duplex ultrasound in order to visualize the tibiopedal vessels. Vascular access can be achieved by using a dedi-cated Micropuncture Pedal Access Set (Cook Medical). This kit comes with a 21-gauge, 4-cm echogenic needle, a 7-cm Micropuncture introducer, an 0.018˝ stainless steel mandril wire, and a hemostasis valve. The Check-Flo he-mostasis valve (Cook Medical) can be attached to the 4 Fr introducer once access is achieved, allowing it to be used as an interventional introducer with a 2.9 Fr inner diameter. If a larger diameter introducer sheath is required, 4 Fr sheaths (and greater) are readily available. Vessel spasm can be prevented through the use of nitroglycerin and heparin.

Catheter, microcatheter, and wire choices are generally operator depen-dent (Table 1); however, in our lab we usually start with 2.6 Fr CXI Sup-port Catheter or 4 Fr Kumpe Cath-eter (both from Cook Medical) to be our go-to catheters. The 2.6 Fr CXI Support Catheter (Cook Medical) fits nicely within the 4 Fr introducer/dila-

tor from the Pedal Access Set and can be used as the main working catheter. Up-sizing to a traditional 4 Fr sheath (e.g. in order to utilize atherectomy or other devices) requires placement of a 0.035˝ wire, which can be inserted through the 4 Fr micro access dilator.

In the setting of chronic total oc-clusion (CTO), initial wire choice is often focused on either hydrophilic or CTO-type wires. Our experience with

Figure 2B. Fluoroscopic guided lo-calization of a posterior tibial artery using calcification for target.

Figure 2A. Ultrasound image depicting the expected location of the tibial artery flanked on either side by its corresponding vein.

Figure 2C. Utilizing angiographic image to localize the pedal vessel for puncture.Cop

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the 0.014˝ Command wire (Abbott Vascular) and 0.014˝ Approach CTO wire (Cook Medical) have been favor-able, however, there are many hydro-philic and total occlusion wires avail-able on the market today. It may be worthwhile to stock several wires with shorter working lengths such as 130 cm for transpedal access cases. We have also used the 0.018˝ 70-degree Glide-wire (Terumo Interventional Systems) with good result, particularly when retrograde recanalization results in sub-intimal wire passage, with the intent of achieving rendezvous in the subintimal space with an antegrade catheter to complete the case. Additionally, if a 4 Fr sheath and 4 Fr catheter are used, one can use a 0.035˝ glidewire for intralu-minal or subintimal crossing (Terumo Interventional Systems).

When utilizing the SAFARI tech-nique (subintimal antegrade flossing us-ing antegrade and retrograde interven-tion), initial attempts are made to pass the retrograde wire directly into the lumen of the antegrade catheter. If this cannot be achieved, a re-entry device and snare may be needed.

We typically use the Outback LTD Re-entry catheter (Cordis Corpora-tion) in combination with either an 0.035˝ Expro Elite snare (Vascular Solu-tions) or 0.014˝ Micro Elite snare (Vas-cular Solutions). The re-entry catheter is typically used as the antegrade de-vice, with the snared re-entry wire then pulled out through the pedal access for through-and-through control.

TECHNIQUEPedal puncture

Transpedal access can be performed under direct ultrasound, fluoroscopic,

and angiographic or roadmap guidance (Figure 2). A handheld duplex ultra-sound can generally identify the desired pedal vessel for puncture.

It is important to recognize the ves-sel in both long- and short-axis views to avoid venous puncture. Compression sonography helps identify the pulsa-tile artery from the adjacent vein, al-though Doppler interrogation may be used when arterial pressure is markedly diminished to ascertain which struc-ture represents the pedal artery. When viewed in short axis, the artery is usu-ally flanked by the accompanying vein on both sides (Figure 2A). In general, if wire passage is free and smooth, one should inject a small amount of contrast to confirm arterial vs venous access. In a heavily calcified pedal vessel one can perform the pedal puncture under di-rect fluoroscopic guidance (Figure 2B).

For noncalcified puncture sites, road-mapping from the antegrade catheter may be performed to identify the ar-tery. When patient motion is a problem, repeated angiographic injections dur-ing access can also be helpful to guide puncture (Figure 2C). To reduce ra-diation exposure to the operator’s hand during fluoroscopic or roadmap guided punctures, a remote needle access tool is distributed by Spectranetics, or surgical clamps can be used to guide the inser-tion needle.

Pedal access

If the micropuncture set 0.018˝ man-dril wire freely passes into the artery, then the nested 3 Fr and 4 Fr dilators are inserted directly. However, if wire movement is restricted, or if the wire cannot be passed into the artery past the point of the solder connection between

the coil tip and wire mandril, then the inner 3 Fr dilator may be inserted alone to allow contrast injection and assurance of successful arterial positioning. Dense-ly calcified puncture sites pose a unique problem in which it may be difficult to advance even the 3 Fr inner dilator into the artery. This is particularly true if the puncture has been too vertical, with kinking of the wire during attempted dilator advancement. In these cases, a reinforced rigid 3 Fr dilator (Cook) may be tried, or the access needle itself may need to be carefully advanced in a ro-tary position to gain more purchase into the artery. The mandril wire can then be advanced until its soldered portion is within the artery, or a wire without a soldered transition (i.e. Roadrunner wire; Cook) may be tried.

Once a secure position in the desired artery is confirmed, choose the appro-priate working access. We will either use the 4 Fr introducer with Check-flo valve accompanied with the 2.6 Fr CXI support catheter as described above or choose a standard 4 Fr vascular sheath and 4 Fr catheter. If dense calcification or the absence of sufficient patent dis-tal artery for wire exchange prevents the introduction of the initial 3 Fr or 4 Fr micropuncture dilator, a different or more distal arterial puncture may be necessary.

Antegrade crossing and catheter/wire

positioning

After failed recanalization of occluded tibial segments (using standard and ad-vanced techniques), the antegrade wire or catheter should be left in place as a target for re-entry from the retrograde access. One may position the antegrade catheter or wire in the most distal aspect

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of the true lumen or in a distal subinti-mal space that would be a good location for re-entry via rendezvous technique (Figure 3).

Retrograde vessel crossing and catheter

positioning

From the tibial access, using a wire and catheter retrograde crossing of the desired tibial vessel is performed using a standard technique. One should be careful to maintain intraluminal pas-sage through the vessel in order to re-enter more proximally. If one is able to secure intraluminal passage through the proximal occluded segment, it is pos-sible to either directly cannulate the an-tegrade catheter or sheath or use a snare to pull the wire from the retrograde sheath through the antegrade sheath. Dedicated catheters are now available

to ease the direct cannulation technique (Quick-Cross Capture Guidewire Re-triever; Spectranetics).

Re-entry device, snare positioning, de-

ployment and “flossing”

If re-entry from the retrograde sheath fails, the re-entry and snare technique is useful to gain “through and through” luminal access. From the antegrade sheath, position the Outback catheter as distally as possible in the subintimal plane (usually at the point of failed re-entry) (Figure 4A). From the retrograde sheath, advance a catheter and snare as proximally as possible. Deploy the Out-back needle and advance the wire from the Outback catheter into the snare and pull the snare through the retrograde sheath (Figure 4B). Fluoroscopy in mul-tiple planes helps to align the puncture towards the snare and reduce the num-ber of passes needed for success. If there is particularly dense calcification at the initially selected re-entry site, then a more proximal or distal position should be tried.

Once the wire is pulled through the retrograde sheath, clamp the wire and remove the Outback from the antegrade sheath. The wire is now “flossed” and one may proceed in the usual manner to revascularize the disease segments. An-gioplasty and stenting as needed ensues in the normal manner using this wire as your working wire.

Hemostasis

After the completion of interven-tion, hemostasis is generally achieved by manual compression with a hemo-static pad; we often use the TipStop bandage (Gambro) for this purpose. Balloon-assisted hemostasis may also

Figure 3. Wire from antegrade sheath left in place as a target for possible re-entry from the retrograde sheath.

Figure 4A. Positioning of the Out-back catheter from the antegrade sheath and positioning of the snare device in overlapping fashion. Note that both snare and sheath in this case are in a subintimal plane.

Figure 4B. Successful snare and pull through of the wire.

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be achieved by inflating an angioplas-ty balloon at low pressure across the puncture site for 3 to 5 minutes. Fi-nally, for peroneal punctures, inflation of an external blood pressure cuff over the calf can be performed for several minutes.

CLINICAL DATAThe reported clinical experience

with transpedal tibial intervention in-volves predominantly case reports and small series.10-15,20-25 In the original se-ries by Spinosa et al, procedural success was accomplished with the SAFARI technique in 12 patients using anterior tibial-dorsalis pedis or posterior tibial access.10 One-year patency in this se-ries (including transpopliteal SAFARI procedures for femoropopliteal occlu-sions) occurred in 58%.10 Gandini et al reported their experience using the SAFARI technique in four patients with nonhealing wounds and femoro-popliteal occlusions.11 Antegrade access was obtained via the ipsilateral common femoral artery, and retrograde puncture through either the distal anterior tibial or posterior tibial artery, with subinti-mal wire snaring at the popliteal level and retrieval through the femoral access to allow subsequent procedure comple-tion. All patients had wound healing by 3 months, and there were no pedal puncture site complications. Paleno and Manzo described direct puncture of the first dorsal metatarsal artery or pedal loop for retrograde catheter insertion in patients in whom the distal anterior tibial, dorsalis pedis, or posterior tibial arteries were not accessible.15 In this report, recanalization and intervention via the distal access was successfully achieved in 24 of 28 patients (86%).

Restoration of straight line flow after intervention resulted in a 71% 6-month limb salvage rate; amputation avoidance was not achieved in any of the cases in which transpedal puncture could not be performed. Similar success rates have been described by Rogers et al, with 85% of 13 patients undergoing favor-able revascularization using combined antegrade and pedal approaches.22 More recently, direct retrograde atherectomy techniques have been applied as a pri-mary treatment strategy.23,25

CONCLUSIONTranspedal interventions represent a

unique and potentially limb preserv-ing recanalization and revascularization technique in patients with CLI and ad-vanced tibial occlusive disease. There will potentially be an increasing preva-lence of patients with complex patterns of infrapopliteal atherosclerotic disease, and familiarity with the SAFARI tech-nique will be of growing importance for interventionalists treating CLI patients.

Editor’s Note: Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript received April 30, 2013; fi-nal version accepted May 20, 2013.

Address for correspondence: John Rund-back, MD, FAHA, FSVM, FSIR, Holy Name Medical Center, Interventional In-stitute, Teaneck, NJ, 07666, USA. Email: jrundback@airsllp.com n

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