Abstract: Objectives. To evaluate the safety and efficacy of transpedal access for the management of complex peripheral artery disease (PAD). Introduction. Critical limb ischemia is associated with high risk of limb loss, as well as cardiovascular and all-cause mortality. Transpedal access is a novel, increasingly utilized technique for the management of complex PAD. Methods. We performed a literature search using PubMed from January 2003 to December 2016. Published studies on transpedal access were studied. We evaluated patient sample demographics, procedure indications, access and target vessel, procedural characteristics, outcomes, and complications. Results. Ten studies and 881 patients were included in our study. The indication for transpedal access was critical limb ischemia in 68.4% and severe claudication in 29.5%. A chronic total occlusion was present in 93.7% (average occlusion length, 206 mm). Access was achieved by ultrasound in 57.1% and by fluoroscopy in 35.7%. The anterior tibial or dorsalis pedis were accessed in 54.7% and the posterior tibial in 28.0%. The angiographic procedural success rate was 92.6%. The most commonly reported complication was dissection (7.49%), followed by perforation (1.36%) and embolization (1.25%). Conclusion. Based on the results of this systematic review, transpedal access appears to be a safe and effective technique for complex PAD.
J INVASIVE CARDIOL 2017;29(12):425-429.
Key words: peripheral arterial intervention, transpedal access, review
The prevalence of peripheral artery disease (PAD) is estimated to be approximately 20% in the general population and up to 29% in higher-risk subgroups (age >70 years or >50 years with history of smoking or diabetes).1 Critical limb ischemia (CLI) affects only 1%-2% of those patients, but is associated with high cardiovascular and all-cause mortality (25% at 1 year and 41% at 2 years) and amputation rates (25%-30% at 1 year).2,3
The increasing prevalence of diabetes mellitus and dialysis-dependent chronic kidney disease has resulted in an increase in lesion complexity. Severely calcified and extensive PAD hinders good endovascular results (primary patency, major adverse limb events, and mortality).4 The optimization of chronic total occlusion (CTO) therapies, re-entry devices, and newer-generation guidewires, balloons, and stents have facilitated the endovascular management of complex lower-extremity artery lesions in patients with CLI. Despite these advances, the failure rate of endovascular approach for complex infrapopliteal lesions remains at 20%-40%.5 One of the challenges and main limitations of endovascular CTO interventions is failure to cross the lesion and gain true lumen access via guidewire or CTO devices.6 Re-entry to the true lumen is more challenging below the knee due to the small vessel size and the limitations of re-entry devices in smaller vessel diameters.7 However, a combination of antegrade and retrograde recanalization attempts via popliteal or pedal arterial access yields high success rates in 90%-100% of patients.8
Transpedal access has emerged as an increasingly utilized vascular access site for the management of complex PAD. A systematic review of the published studies on transpedal access is currently unavailable; therefore, this review will examine currently available data.
A prospective protocol was developed. We performed a literature search of PubMed from January 2003 to December 2016. Published studies with the following characteristics were included: (1) use of percutaneous transpedal access during endovascular interventions; (2) at least 5 patients examined; and (3) manuscript published in English. The primary outcome of interest was safety and efficacy of the transpedal access. The medical subject heading (MeSH) terms “retrograde tibial,” “retrograde endovascular,” “retrograde recanalization,” and “transpedal” were used. All titles and abstracts of the articles were evaluated. Bibliographies of relevant studies and the “related articles” link in PubMed were used to identify additional studies. After preliminary article selection based on the titles and abstracts, full articles were examined. The type of study, access-site characteristics, demographics, target vessel, angiographic results, and complications were reviewed. In papers with multiple treatment arms, we included only patients who received the studied intervention. When the transpedal access was reported in combination with other retrograde vessel access (transpopliteal or distal superficial femoral artery [SFA]), we only included studies that reported patency rates specific to pedal access.
Data extraction. Studies were selected and data were extracted independently by two reviewers (KM and MC). Disagreements were resolved by consensus among reviewers. The studies were evaluated carefully for duplicate or overlapping data. We recorded the type of study, sample size, and country where the procedures were performed. Demographic data, risk factors, indication for the procedure were analyzed and included. We described the devices and medications used during the procedure when reported, the procedure time, contrast volume and details about the access vessel, the target vessel, the type of imaging used to facilitate the access and the percentage of CTOs treated. Finally, we noted the angiographic success and complication rates.
Statistical analysis. The qualifying studies were observational studies with no control group, so we could only estimate incidence rates (ie, the event rate at the end of study follow-up). Rates were pooled across studies and we used the random-effects model for meta-analysis. Proportions were calculated as a number of patients experiencing a particular event over the total number of patients in a study. We used the I2 statistic to assess heterogeneity of the selected studies, with a value >50% implying significant heterogeneity. Publication bias was assessed visually by asymmetry in funnel plots and formally using Egger’s regression test (Supplemental Figure S1). For the meta-analysis, statistical analysis was done using StatsDirect software.
Study types (Table 1). Ten studies (881 patients) met the selection criteria and were included in our study.5,8-16 One study was international and multicenter, 4 studies were performed in the United States, 3 were performed in Asia, and 2 were performed in Europe. One study was a prospective, observational case series, 7 studies were retrospective, observational case series, and 2 studies were retrospective comparative (1 compared two hemostasis devices and 1 compared two crossing techniques).
Demographic characteristics, risk factors, and procedure indication (Table 2). The mean patient age was 72.6 years old and 64.1% were male. The most common risk factors were hypertension (88.6%), diabetes mellitus (60.1%), smoking (47.8%), coronary artery disease (30.3%), and chronic kidney disease (18.8%). In most patients, the indication was CLI (Rutherford class 4-6 in 68.4%, severe claudication with Rutherford class 3 in 29.5%, and only a few with mild claudication or acute limb ischemia). All patients had CLI in three studies (Tay, Ruzsa, and Botti), while only 48.1% of patients had CLI in the study by Kwan.
Procedural characteristics (Tables 3 and 4). Ultrasound was used to gain access in most cases (57.1%) and fluoroscopy in about one-third of all cases (35.7%). All cases were accessed via ultrasound guidance in the series by Mustapha and Kwan, while access was achieved via fluoroscopy in five studies (Chou, Montero-Baker, Botti, Rogers, and Ruzsa).
The anterior tibial (AT) and dorsalis pedis arteries were the most commonly accessed vessels (54.7%), followed by the posterior tibial (PT) artery (28.0%) and peroneal artery (7.5%). Preference for the PT artery was higher in the studies by Rogers (84.6%), Hua (66.7%), and Botti (66.7%), while AT and pedal access was preferred in the studies by Kwan (76.1%) and Ruzsa (70.6%).
The majority of patients (93.7%) had a CTO and the average occlusion length was 206.0 ± 125.0 mm. All patients had a CTO in seven studies (Walker, Chou, Montero-Baker, Botti, Rogers, Tay and Hua). The target vessel was an infrapopliteal vessel in 67.1%, the popliteal in 18.7%, and the SFA in 43.0% of cases. In several cases, >1 vessel was recanalized. The average procedure time was 95.8 ± 91.2 min and the average contrast use was about 63.9 ± 98.0 mL. The reported angiographic procedural success rate was 92.6%.
Devices (Table 5). A 21 G needle was used in most studies, and nitroglycerin or verapamil was given through the sheath to prevent vessel vasospasm. A standard dose of unfractionated heparin was administered or a goal activated clotting time was targeted (200-250 sec or 250-300 sec). Most operators used 0.014˝ or 0.018˝ guidewires as a “workhorse wire” and then upgraded to guidewires with stiffer tips or larger diameters.
Complications (Table 6). The most common complication was vessel dissection (7.75%), followed by perforation, embolization, hematoma, pseudoaneurysm and arteriovenous fistula formation, and access-site infection. The highest percentage of perforation was reported in the studies by Montero-Baker (5.88%) and Chou (4.9%), embolization in the series by Hua (4.76%), and dissection in the studies by Chou (63.7%) and Hua (9.5%). In the 881 studied patients, there were 9 cases of hematoma, 4 cases of pseudoaneurysm formation, and 3 cases of arteriovenous fistula formation and incisional infection.
With the continuous optimization of the endovascular device armamentarium and operator experience, the management of highly complex PAD is feasible. CLI is a global epidemic that is expected to expand with the increasing rates of diabetes and kidney disease. Retrograde revascularization is an important skillset to improve the limb salvage rates in patients with higher TASC II class.17
Popliteal access was previously the preferred access site for attempted retrograde recanalization. However, it may be challenging due to: (1) occasional disease involvement or occlusion of the popliteal artery; (2) increased risk of bleeding at the access site, arteriovenous fistula formation, and radiation exposure to the operator; (3) inability to treat infrapopliteal disease due to sheath location and, if occlusive, worsening of ischemia; and (4) need to reposition the patient to the prone position.18
This systematic review demonstrates that transpedal access is safe and effective. Transpedal access was mainly utilized as an adjunct access site when antegrade recanalization attempts were unsuccessful. The majority of patients were older, with several comorbidities and advanced PAD with CLI or severe claudication. CTOs were present in >90%, with average occlusion lengths >220 mm. Despite the complexity of treated lesions, a success rate of >90% was achieved with relatively low contrast volume, reasonable procedure times, and low complication rates. There were no reported deaths or major complications associated with transpedal access.
A short 21 G needle is typically used to gain access. Unlike transradial access with similar anatomy and technique, palpation is rarely helpful because the pressure and flow in the accessed artery is low. In older studies, fluoroscopy was the prevalent imaging method to achieve vascular access; however, ultrasound has been increasingly utilized. Several centers of excellence today use ultrasound imaging to guide access as well as visualize the intraluminal course of the guidewire inside the superficial course of the AT and PT arteries.
The PT is typically accessed behind the medial malleolus and the AT at the transition of the dorsalis pedis to the AT just above the instep of the foot. In those locations, the artery size can accommodate sheath entrance, the risk of compartment syndrome is minimal, and postprocedure hemostasis is easy (Figure 1). A 0.014˝ or 0.018˝ wire is advanced through the needle and a 4 Fr hydrophilic sheath is positioned. Nitroglycerin and verapamil are administered through the sheath and unfractionated heparin is given intravenously to achieve a therapeutic ACT >250 sec.
In our study, there was a wide variation in the sizes and types of guidewires and support catheters. We typically use a 0.014˝ workhorse wire with a support catheter and upsize the guidewire size to 0.018˝ or 0.035˝ or the guidewire profile with stiffer tips (3, 12, or 30 gram wires), based on the size and anatomy of the target vessel.
The AT and PT are preferred over the peroneal artery for access. This may be due to two reasons: (1) the peroneal artery tends to be less diseased and is usually the artery that keeps the pedal vessels open through collaterals; and (2) it is technically more challenging to access due to its anatomical position deep to the inter-osseous membrane of the leg.
Several techniques have been used during transpedal access. The wire-balloon only (WBO) technique was described by Montero-Baker et al and involves the advancement of the wire and balloon without sheath insertion.5 This technique maintains the lowest profile advanced via the transpedal access in order to prevent access complications. The subintimal arterial flossing with antegrade-retrograde intervention (SAFARI) technique was introduced by Gandini and describes the subintimal entrance of two guidewires, with antegrade and retrograde wires meeting in the subintimal space of the CTO and the assistance of balloon inflation.19 The controlled antegrade and retrograde subintimal tracking (CART) and reverse-CART techniques describe the inflation of a balloon through an antegrade or retrograde access, dissecting the plaque, and modifying the lesion. This allows the “opposite” guidewire to enter easily to the true lumen. The tibiopedal arterial minimally invasive retrograde revascularization (TAMI) technique has been described by Mustapha and describes the use of transpedal access as the only access site to treat run-off disease.20
Balloon angioplasty, stenting, directional and rotational atherectomy, thrombectomy, and thrombolysis have been utilized via the transpedal access.16 The only limitation for device use is the sheath size, although sheathless techniques have been previously successfully used.
Study limitations. Our study is limited by the use of observational studies and the moderate sample size of previous publications. There were important differences between the studied manuscripts regarding patient selection, indications, imaging to achieve access, preferred access artery, and procedural characteristics.
Transpedal access has emerged as an evolving technique for the management of complex lower-extremity PAD. The existing data demonstrate its safety and efficacy in the most challenging PAD subgroup of CLI patients with long CTOs, run-off disease, and previous antegrade technical failures. Larger randomized trials with longer-term follow-up are needed to establish the long-term safety and efficacy of this technique.
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From the 1Pepin Heart Institute Florida Hospital, Tampa, Florida; 2Division of Cardiovascular Medicine, University of Utah, Salt Lake City, Utah; 3Metro Health Hospital, Wyoming, Michigan; 4Baylor College of Medicine, Houston, Texas; 5University of Texas, Houston, Texas; 6University of Texas, M.D. Anderson Cancer Center, Houston, Texas; and 7Weill Cornell Medical College/New York Presbyterian Hospital, New York, New York.
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 submitted October 30, 2017, provisional acceptance given November 1, 2017, final version accepted November 6, 2017.
Address for correspondence: Konstantinos Marmagkiolis, MD, MBA, FACC, FSCAI, 1945 Noor St, Apt 212, Wesley Chapel, FL 33544. Email: firstname.lastname@example.org