Pedal-Plantar Loop Technique for a Challenging Below-the-Knee Chronic Total Occlusion: A Novel Approach to Percutaneous Revascul

Arterial revascularization by means of percutaneous transluminal angioplasty (PTA) is being increasingly used for the treatment of patients with severely symptomatic peripheral artery disease (i.e., those with critical limb ischemia). This phenomenon has been largely dependent on technical and technological advancements, such as the introduction of low-profile and dedicated devices, as well as the development of subintimal angioplasty.^1,2 While PTA for critical limb ischemia has recently shown clinical results equivalent to those of the established standard of care, i.e., bypass surgery, percutaneous recanalization of below-the-knee occlusions can still be unsuccessful in up to 20% of patients, even in high-volume and expertise centers.³ There is thus an acute need for technical refinements for percutaneous revascularization of below-the-knee atherosclerotic disease. We hereby report a novel approach to recanalize challenging infragenicular total occlusions (i.e., those without a visible proximal occlusion stump) which we have defined as the “pedal-plantar loop technique”. Case Report. A 70-year-old diabetic female, symptomatic for a ischemic rest pain in the left foot for the past several months, was referred to our center for peripheral arteriography and potential percutaneous revascularization. Antegrade common femoral artery puncture was performed using a 19 gauge needle (Cordis Corp., Miami, Florida), and a slow-flow injection (6 ml at 3 ml/second, 300 psi) was performed through the needle to confirm the good position in the common femoral artery and to allow wiring of the superficial femoral artery. A 6 Fr 10 cm sheath was then inserted (Terumo Medical Corp., Somerset, New Jersey), 7,500 IU of unfractionated heparin were administered intra-arterially, and diagnostic angiography was performed using the side arm of the introducer sheath. Left lower limb arteriography disclosed long and total occlusions of the anterior tibial, dorsalis pedis and posterior tibial arteries, with critical stenoses of the peroneal artery (Figure 1). We initially attempted percutaneous revascularization of the anterior tibial artery occlusion, given the lack of a visible proximal occlusion stump in the posterior tibial artery, and for this task, chose a 0.014 inch hydrophilic wire (Pilot 200, Guidant Corp., Indianapolis, Indiana) and a 3.0 mm over-the-wire balloon (Amphirion, Invatec, Brescia, Italy). We easily crossed and dilated the entire anterior tibial occlusion, but were unsuccessful in crossing the chronic occlusion of the dorsalis pedis artery. During several wiring attempts, we nonetheless were able to engage a perforator branch which led us to the plantar branch and distal posterior tibial artery by means of a pedal-plantar loop (Figure 2). Using a lower-profile over-the-wire balloon (2.0 mm Amphirion, Invatec), we then retrogradely recanalized the entire posterior tibial artery employing a subintimal angioplasty technique. Indeed, exchanging for a 0.014 inch guidewire (300 cm Choice PT Graphix, Boston Scientific Corp., Natick, Massachusetts) enabled us to reach the tibio-peroneal trunk. Since the shaft of the balloon (the longest available in our laboratory) measured only 120 cm in length, it was unable to be advanced retrogradely beyond the mid tract of the posterior tibial artery. While leaving the “loop” wire in place as a marker in the posterior tibial artery, we then antegradely approached the posterior tibial artery occlusion using an additional 0.014 inch wire (Pilot 200) and the 3.0 mm over-the-wire balloon. We were thus able to reach the true plantar branch, and completed PTA of the posterior tibial artery with prolonged (3 minutes) and high-pressure (14 atm) balloon inflations. Figure 3 shows the final satisfactory angiographic result in both anterior and posterior tibial arteries in the absence of significant residual stenoses or flow-limiting dissections. Femoral hemostasis was achieved with manual compression, and the patient was sent to the recovery ward. The patient’s subsequent hospital stay was uneventful, with persistence of both pedal and posterior tibial pulses and disappearance of her rest pain. She was discharged on lifelong 100 mg aspirin daily and a 1-month course of ticlopidine 250 mg twice daily. Discussion. While percutaneous recanalization appears equivalent to bypass surgery in the management of patients with critical lower limb ischemia, standard percutaneous approaches and techniques are still inadequate, as procedural failure can occur in up to one-fifth of the cases, even in experienced hands.³ In addition to the traditional contralateral approach, ipsilateral antegrade (i.e., femoral) and retrograde (e.g., pedal or posterior tibial)⁴ accesses have been shown to be beneficial in increasing success rates, especially in the most challenging chronic occlusions. Nonetheless, even these strategies may fail or prove infeasible (e.g., when the distal vessels are also diseased). In the present article, we provide details on a new approach to recanalize challenging below-the-knee chronic total occlusions, the pedal-plantar loop technique. This is based on the creation of a loop with the guidewire from the anterior tibial to the posterior tibial arteries by means of guidewire tracking through the foot collaterals (thus the name “pedal-plantar loop”). We believe that this technique may be of particular value whenever a proximal occlusion stump is unavailable, when a dissection flap or a perforation in the proximal tract of the target vessel impairs guidewire advancement, as well as when distal disease makes retrograde percutaneous puncture impossible. In our experience, recanalization by means of a pedal-plantar loop (or, similarly, plantar-pedal loop when the anterior tibial artery is recanalized retrogradely) has the advantage of employing minimally invasive retrograde recanalization. The approach is indeed minimally invasive, as no other percutaneous accesses are employed (at odds with the retrograde pedal or posterior tibial approaches), and the use of retrograde guidewire tracking minimizes the risk of ending up in a collateral branch while tackling the total occlusion. On the other hand, both the mechanical properties of guidewire and balloon are stressed to their most extreme limits, as very challenging angles and tortuosities in the foot must be conquered to complete retrograde below-the-knee recanalization using the plantar-pedal loop technique. Thus the need for very low-profile balloons (e.g., the Amphirion over-the-wire balloon) and exchange-length guidewires. While this approach is novel and to date no other similar reports are available in the literature, some similarities to a recent technique described in coronary interventions can be found. Indeed, Rosenmann et al reported in 2006 on 3 cases in which challenging chronic coronary occlusions were successfully crossed by using a retrograde approach from collaterals or from bypassed vessels.⁵ These authors also provide important insights on why a wire should more easily cross an occlusion from a retrograde approach, which includes the fact that the wire may enter the lesion from a preexisting channel with a more crossable stump at its end, and the potential differences in occlusion composition (such as less fibrotic or calcified tissue in the distal part of the occlusion than in the proximal part).⁵ In conclusion, the pedal-plantar loop technique for percutaneous recanalization of below-the-knee arterial disease appears to be a promising new tool in the interventionist’s armamentarium, either on a bailout basis (i.e., in cases when antegrade revascularization fails), or electively (such as in the present clinical vignette, when traditional approaches are deemed infeasible).

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