Peripheral Chronic Total Occlusions Research Articles

Best crossing of peripheral chronic total occlusions.

Together with colleagues from different disciplines, including cardiologists, interventional radiologists and vascular surgeons, committee members of the of the German Society of Angiology (Deutsche Gesellschaft für Angiologie [DGA]), developed a novel algorithm for the endovascular treatment of peripheral chronic total occlusive lesions (CTOs). Our aim is to improve patient and limb related outcomes, by increasing the success rate of endovascular procedures. This can be achieved by adherence to the proposed crossing algorithm, aiding the standardization of endovascular procedures. The following steps are proposed: (i) APPLY Duplex sonography and if required 3D techniques such as computed tomography or magnetic resonance angiography. This will help you to select the optimal access site. (ii) EVALUATE the CTO cap morphology and distal vessel refilling sites during diagnostic angiography, which are potential targets for a retrograde access. (iii) START with antegrade wiring strategies including guidewire (GW) and support catheter technology. Use GW escalation strategies to penetrate the proximal cap of the CTO, which may usually be fibrotic and calcified. (iv) STOP the antegrade attempt depending on patient specific parameters and the presence of retrograde options, as evaluated by pre-procedural imaging and during angiography. (v) In case of FAILURE, consider advanced bidirectional techniques and reentry devices. (vi) In case of SUCCESS, externalize the GW and treat the CTO. Manage the retrograde access at the end of the endovascular procedure. (vii) STOP the procedure if no progress can be obtained within 3 hours, in case of specific complications or when reaching maximum contrast administration based on individual patient's renal function. Consider radiation exposure both for patients and operators. In this manuscript we systematically follow and explain each of the steps (i)-(vi) based on practical examples from our daily routine. We strongly believe that the integration of this algorithm in the daily practice of endovascular specialists, can improve vessel and patient specific outcomes.

Dual-Energy Computed Tomography as an Adjunct in the Evaluation of Peripheral Chronic Total Occlusions: A Feasibility Study

This study investigated the role of dual-energy computed tomography (CT) for lesion characterization in patients with peripheral arterial disease manifesting with chronic total occlusions (CTOs). Forty-one symptomatic patients with CTOs underwent dual-energy CT angiography before endovascular treatment. The lesions were subsequently analyzed in a dedicated workstation, and 2 indexes—dual-energy index (DEI) and effective Z (Zeff)—were calculated, ranging from 0.0027 to 0.321 and from 6.89 to 13.02, respectively. Statistical analysis showed a significant correlation between the DEI and Zeff values (P < .001). The interobserver intraclass correlation coefficient was 0.91 for the mean Zeff values and 0.86 for the mean DEI values. This technique could potentially provide useful information regarding the composition of a CTO.

Treating Peripheral Chronic Total Occlusions: Putting a New Device in Perspective

The article “A Multinational, Single-Arm Pivotal Study Assessing the Performance of the SoundBite Crossing System for Peripheral Chronic Total Occlusions (The PROSPECTOR Study)” published in this month’s JVIR introduces a new device for the management of peripheral chronic total occlusions (CTOs) (1). The study is a multicenter single-arm trial investigating the technical success and safety of an active guide wire that delivers acoustic shock waves in crossing CTOs of the femoropopliteal segments, building upon a previously published feasibility study (2).

In-hospital outcomes of endovascular versus surgical revascularization for chronic total occlusion in peripheral artery disease.

The outcome of endovascular intervention (EVI) compared vs. surgical revascularization in patients with peripheral artery disease (PAD) due to chronic total occlusion (CTO) is unknown. Using the National Inpatient Sample database between 2007 and 2014, we identified all PAD patients with CTO who had limb revascularization. Multivariate analysis was performed to estimate the odds of in-hospital mortality and adverse outcomes between both groups. A total of 168,420 patients who had peripheral CTO and underwent limb revascularization were identified. 99,279 underwent EVI, and 69,141 underwent surgical revascularization. The patients who underwent EVI were younger, more likely to be women and African American, and less likely to be white (p< 0.001 for all). EVI was associated with lower in-hospital mortality (1.2% vs 1.7%, adjusted odds ratio [aOR]: 0.54; 95% confidence interval [CI] 0.50-0.59). The EVI group had higher vascular complications, major bleeding, acute kidney injury (AKI), and major amputation compared with surgical revascularization. A subgroup analysis on patients with critical limb ischemia showed lower mortality in the EVI group (1.4% vs. 1.9, aOR 0.56; 95% CI 0.50-0.63). Although there was no difference in the incidence of AKI or major amputation between the two groups, the EVI group had higher vascular complication rates and major bleeding events. EVI in PAD with CTO is associated with lower in-hospital mortality, likely due to the procedure's less-invasive nature; however, it is associated with higher postprocedural complications likely due to the CTO's complexity.

In Vivo Magnetic Resonance Histology of Peripheral Arterial Chronic Total Occlusions in Patients With Chronic Limb-Threatening Ischemia

In Vivo Magnetic Resonance Histology of Peripheral Arterial Chronic Total Occlusions in Patients With Chronic Limb-Threatening Ischemia

A Robotically Steerable Guidewire With Forward-Viewing Ultrasound: Development of Technology for Minimally-Invasive Imaging.

The current standard of care for peripheral chronic total occlusions involves the manual routing of a guidewire under fluoroscopy. Despite significant improvements in recent decades, navigation remains clinically challenging with high rates of procedural failure and iatrogenic injury. To address this challenge, we present a proof-of-concept robotic guidewire system with forward-viewing ultrasound imaging to allow visualization and maneuverability through complex vasculature. A 0.035" guidewire-specific ultrasound transducer with matching layer and acoustic backing was designed, fabricated, and characterized. The effect of guidewire motion on signal decorrelation was assessed with simulations and experimentally, driving the development of a synthetic aperture beamforming approach to form images as the transducer is steered on the robotic guidewire. System performance was evaluated by imaging wire targets in water. Finally, proof-of-concept was demonstrated by imaging an ex vivo artery. The designed custom transducer was fabricated with a center frequency of 15.7 MHz, 45.4% fractional bandwidth, and 31dB SNR. In imaging 20 μm wire targets at a depth of 6mm, the lateral -6dB target width was 0.25 ± 0.03mm. The 3D artery reconstruction allowed visualization of vessel wall structure and lumen. Initial proof-of-concept for an ultrasound transducer-tipped steerable guidewire including 3D image formation without an additional sensor to determine guidewire position was demonstrated for a sub-mm system with an integrated ultrasound transducer and a robotically-steered guidewire. The developed forward-viewing, robotically-steered guidewire may enable navigation through occluded vascular regions that cannot be crossed with current methods.

Retrograde Tibioperoneal Access for Complex Infrainguinal Occlusions: Short- and Long-Term Outcomes of 554 Endovascular Interventions

ObjectivesThis study sought to report short- and long-term efficacy and safety outcomes of retrograde tibioperoneal access for endovascular treatment of chronic total occlusions (CTOs). BackgroundAntegrade recanalization of peripheral CTO is associated with a high failure rate and retrograde puncture of tibioperoneal arteries has been adopted to overcome this limitation. MethodsWithin a retrospective single center cohort study, data of 554 infrainguinal occlusions were acquired in which a retrograde puncture of at least 1 infrapopliteal artery became necessary. Techniques used for access, retrograde lesion crossing, and antegrade treatment modalities were recorded. Next to short-term outcomes, long-term results through 4 years were described using survival analysis. ResultsThe majority of patients (71.5%) had critical limb ischemia (CLI) and occlusion locations were the femoropopliteal segment (35.9%), infrapopliteal segment (42.6%), or both segments (21.5%). Retrograde access was most commonly performed via the proximal (28%) or distal (34%) anterior tibial artery. Retrograde access could be established in 98.6% and subsequent lesion crossing was successful in 95.1%. Complications due to distal puncture were rare (3.3%). At 1 year, freedom from target lesion revascularization and restenosis were 74.6 ± 3.7% and 67.5 ± 4.4% in claudicants and 62.2 ± 2.8% and 36.0 ± 4.4% in CLI patients, respectively. Late complications at the distal puncture site after a median follow-up time of 234 days comprised 1 stenosis, 7 occlusions, and 3 clinically nonrelevant arteriovenous fistula occurring only in CLI patients. ConclusionsRetrograde tibioperoneal access is a safe option for recanalization of complex CTOs after a failed antegrade approach. Complications at the puncture site were rare.

Use of the Ocelot catheter in iliac chronic total occlusion intervention

The optical-coherence tomography guided Ocelot catheter has previously been shown to be a safe and effective tool for crossing peripheral chronic total occlusions. However, the existing literature focuses mostly on the superficial femoral artery, without prior evidence of use within the suprainguinal vasculature. We present the first known cases of the Ocelot catheter for revascularization of chronic total occlusions in the iliac vasculature. In the first case a retrograde approach is used for intervention of the right common iliac artery, while in the second case an antegrade approach is used for revascularization of the left external iliac artery. In this case report we first demonstrate as proof of feasibility the use of the Ocelot catheter in suprainguinal artery chronic total occlusions.

Percutaneous intentional intra-luminal-assisted recanalization (PILAR technique) of challenging chronic total occlusions using a high-frequency vibration device.

Recanalization of peripheral chronic total occlusions (CTO) is technically challenging especially in cases of in-stent and/or pre-stent and heavily calcified lesions. A high-frequency vibrational device (HFVD) was first used as a secondary-intention device in CTO recanalizations when they were refractory to a guidewire. The aim of this study was to assess the safety and efficacy of the HFVD as a first-line treatment for challenging CTOs and thus to define the percutaneous intentional intraluminal-assisted recanalization (PILAR) technique. Fifty-two patients were treated with the HFVD. Only challenging CTOs were included: 7 pre-stent, 7 in-stent, and 38 highly calcified CTOs. Technical success was defined as the ability to cross the CTO using the HFVD. Secondary outcome was defined as successful intraluminal crossing. Safety endpoints were procedure-related thromboembolism or perforation. Patients were followed up at 3 months and 1 year. The technical success rate for recanalization was 90%, of which 83% were intraluminal. The mean recanalized length was 91 ± 44 mm. One thromboembolic complication occurred, which was subsequently treated with thromboaspiration. Three-month and 1-year primary patency rates were 92% and 79%, respectively. HFVD-based PILAR is a safe and effective technique for in-stent or pre-stent CTO recanalization of long and calcified lesions. • Intraluminal recanalization is the preferred procedure in heavily calcified or pre-/in-stent CTO. • First-line use of assisted intraluminal recanalization for CTO defines the PILAR technique. • HFVD-based PILAR is safe and provides a high success rate for challenging CTO recanalization.

Performance Assessment of a Radiofrequency Powered Guidewire for Crossing Peripheral Arterial Occlusions Based on Lesion Morphology.

Endovascular wires and devices for peripheral arterial disease therapy have evolved greatly, yet failure rates of these procedures remain high. Information on lesion composition may inform device selection to improve the success rates of these procedures. This paper, presents an approach for informed guidewire selection. The objective of this study is to quantitatively assess the performance of a radiofrequency powered guidewire in the crossing of various morphology types of peripheral chronic total occlusions. Samples taken from amputated patient limbs are characterized by magnetic resonance imaging. Using a customized catheter test station, the performance of a radiofrequency powered guidewire in puncturing these lesions is compared to a conventional guidewire, and to itself when not powered. The analysis includes quantitative and statistical comparisons of the puncture forces experienced by the different guidewires in "hard" vs. "soft" lesions as well as qualitative assessment of deflections, buckling and puncture success of the wires. Results indicate that the use of radiofrequency ablation significantly reduces the required puncture force, reduced events of buckling and deflection, and resulted in a significantly higher puncture success rate.

Performance Assessment of a Radiofrequency-Powered Guidewire for Crossing Peripheral Arterial Occlusions Based on Lesion Morphology

The goal of this study was to assess and to compare the performance of a conventional guidewire and a radiofrequency (RF)-powered guidewire for crossing various types of peripheral chronic total occlusions as characterized by magnetic resonance imaging. In this study, 27 samples of peripheral arterial plaques were excised from two amputation patients. To characterize the lesion morphology, each sample was imaged with 7T magnetic resonance imaging using ultrashort echo time and T2-weighted (T2W) sequences (97 × 97 × 97 μm3 voxels) and imaged with micro-computed tomography (50 × 50 × 50 μm3 voxels). The lesions were categorized as “soft” (fat, thrombus, microchannels, or loose fibrous tissue—bright on T2W images) or “hard” (dense fibrous tissue/collagen and segmented calcium—gray on ultrashort echo time and dark on T2W images)1-3 as shown in Fig 1. Using a custom catheter test station, the load cell advanced the guidewires at a constant velocity of 0.05 mm/s while recording the exerted forces. The performance of a 0.035-inch conventional hydrophilic guidewire was compared with a 0.035-inch RF guidewire with RF power (on; 50W maximum at 468 kHz) and without RF (off). For hard lesions, the conventional guidewire failed to penetrate (n = 6), whereas the RF guidewire successfully punctured (n = 3) with forces of 1.34 ± 0.36 N when off and significantly lower forces of 0.54 ± 0.12 N when on (n = 3; one-tailed t-test; P < .03; Fig 2). For soft lesions, the conventional guidewire penetrated the samples (n = 5) with puncture forces of 0.25 ± 0.20 N, whereas the RF guidewire experienced forces of 0.62 ± 0.28 N when off (n = 5) and 0.04 ± 0.03 N when on (n = 5; one-way analysis of variance; F(2,12); P < .002). These results indicate that using RF power significantly reduces the required amount of force to puncture hard lesions; where the conventional guidewire fails, the RF guidewire succeeds. Future work will analyze the safety aspect of using RF in vivo.

Commentary: ReFLAP: A New Sheath Inflow Occlusion Technique to Prevent Distal Embolization During Endovascular Treatment of Peripheral Chronic Total Occlusions

Commentary: ReFLAP: A New Sheath Inflow Occlusion Technique to Prevent Distal Embolization During Endovascular Treatment of Peripheral Chronic Total Occlusions

Recanalization of peripheral chronic total occlusions: ‘no fancy devices, just a crossing catheter’

ABSTRACTBackground: Chronic total occlusions (CTOs) are challenging to treat endovascularly. Classic subintimal approach is offering only moderate success rates mainly due of the lack of dedicated crossing catheters. Purpose of this study is to assess the acute procedural success of the use of a novel hydrophilic crossing catheter in the recanalization of peripheral CTOs.Materials and methods: This is a retrospective, single-centre study of patients with femoropopliteal CTOs. Revascularization was performed with the use of the NaviCross®- crossing catheter (Terumo Europe). Technical, procedural success and complications were assessed.Results: Thirty-two patients were included in the study. Mean age was 65.9 (46–85) years; Critical limb ischemia was the indication for the procedure in 26 (81%). Target vessels included 12 superficial femoral arteries, 9 popliteal, and 11 femoropopliteal segment lesions. Mean length was 85 (50–350) mm; 21(65.6%) lesions were heavily calcified. In all cases a sub-intimal approach was used; in 21 cases the procedure was performed as a day case. Technical success was achieved in 31 (96.8%) cases. Recanalization was achieved with a guidewire in 22 (71%) lesions and with the catheter alone in 9 (29%) cases. Procedural success was achieved in all lesions. No major adverse events occurred.Conclusion: The use of the NaviCross®- crossing catheter showed high rate of technical and procedural success in challenging femoropopliteal CTOs without significant complications. The use of this catheter needs to be considered as the first approach for CTOs prior to the use of any other more complex re-entry device.

Puncturing Plaques

Purpose: To test and validate magnetic resonance imaging (MRI) sequences for peripheral artery lesion characterization and relate the MRI characteristics to the amount of force required for a guidewire to puncture peripheral chronic total occlusions (CTOs) as a surrogate for immediate failure of endovascular therapy. Methods: Diseased superficial femoral, popliteal, and tibial artery segments containing 55 atherosclerotic lesions were excised from the amputated limbs of 7 patients with critical limb ischemia. The lesions were imaged at high resolution (75 μm3 voxels) with T2-weighted (T2W) and ultrashort echo time (UTE) sequences on a 7-T MR scanner. The MR images (n=15) were validated with micro–computed tomography and histology. CTOs (n=40) were classified by their MR signal characteristics as “soft” (signals indicating fat, thrombus, microchannels, or loose fibrous tissue), “hard” (collagen and/or speckled calcium signals), or “calcified” (calcified nodule signals). A 2-kg load cell advanced the back end of a 0.035-inch stiff guidewire at a fixed displacement rate (0.05 mm/s) through the CTOs, and the forces required to cross each lesion were measured. Results: T2W images showed fat as hyperintense and hardened tissue as hypointense. Calcium and thrombus appeared as a signal void in conventional MRI sequences but were easily identified in UTE images (thrombus was hyperintense and calcium hypointense). MRI accurately differentiated “hard,” “soft,” and “calcified” CTOs based on associated guidewire puncture force. The guidewire could not enter “calcified” CTOs (n=6) at all. “Hard” CTOs (n=9) required a significantly higher (p<0.001) puncture force of 1.71±0.51 N vs 0.43±0.36 N for “soft” CTOs (n=25). Conclusion: MRI characteristics of PAD lesions correlate with guidewire puncture forces, an important aspect of crossability. Future work will determine if clinical MR scanners can be used to predict success in peripheral vascular interventions.

Abstract 295: Magnetic Resonance Imaging Characterization of Peripheral Arterial Chronic Total Occlusions With MicroCT and Histologic Validation

Objectives: Guidelines recommend surgical bypass for peripheral chronic total occlusions (CTOs). Endovascular revascularization, however, offers improved morbidity and shorter length of hospitalization. Not all lesions are amenable to this technique but predicting crossability is difficult due to limitations in characterizing CTOs with current imaging techniques. This study demonstrates the ability of MRI to characterize peripheral CTO components with microCT and histologic validation. Methods: MRI was performed on 15 excised human peripheral arterial CTO segments from 4 patients. Each sample was imaged at 7 Tesla at high resolution (75μm3 voxels) to produce T2- and T2*-maps using ultrashort echo (UTE) sequences with echo times: {20μs, 500μs, 1ms}. A T2* difference image was produced by subtracting the UTE images and a phase map was constructed. The T2, UTE 20μs and T2* difference images were used together to differentiate CTO components. MicroCT and histology were used to validate regions of interest (ROIs). Results: 3 independent reviewers identified 47 ROIs. There was excellent agreement between MRI and microCT for calcium (sensitivity 87%, specificity 99%). There was also good agreement between MRI and histology for adipose tissue (100%, 100%), soft tissue (97%, 97%), thrombus (78%, 100%), collagen (83%, 94%) and open lumen (95%, 98%). Conclusions: These results demonstrate the potential of high-resolution T2 and T2* imaging using UTE, to characterize lesion components in human peripheral CTOs. Further work is required to better differentiate thrombus from collagen. This study provides the foundation for future studies in determining the lesion crossability in CTOs.

MRI characterization of peripheral arterial chronic total occlusions at 7 Tesla with microCT and histologic validation

Background Current treatment guidelines recommend surgical bypass for peripheral chronic total occlusions (CTOs)[1]. Percutaneous transluminal angioplasty (PTA), however, offers a less invasive approach with improved perioperative morbidity, shorter length of hospital stay, and lower cost[2]. Not all lesions are amenable to this technique and there is a significant primary failure rate[2]. Predicting lesion crossability is difficult because current imaging techniques offer limited information with which to characterize CTOs. The ability to distinguish between hard and soft biological substances that compose a CTO can aid procedural planning and facilitate intervention. This pilot study demonstrates the ability of high resolution MRI to characterize peripheral CTO components with microCT and histologic validation.

TCT-538 Lumivascular Approach To Crossing Chronic Total Occlusions Without Fluoroscopy

Case series where the use of optical coherence tomography (OCT) greatly reduced or eliminated fluoroscopy during the crossing of peripheral arterial chronic total occlusions (CTOs) when using the Ocelot catheter (Avinger Inc, CA). Fifteen patients, with sixteen lesions (n=16) were successfully

Endovascular treatment of infrainguinal chronic total occlusions using the TruePath device: features, handling, and 6-month outcomes.

To report experience with a recently approved peripheral chronic total occlusion (CTO) crossing device in the superficial femoral (SFA), popliteal, and below-the-knee (BTK) arteries. Thirteen patients (all men; mean age 68.6±7.9 years) from the XLPAD registry (ClinicalTrials.gov identifier NCT01904851) were treated between April 2012 and August 2013 with the TruePath device after an unsuccessful guidewire crossing attempt. More than half of the patients had diabetes mellitus. Most lesions were TASC classification type C (n=5) or D (n=6), with mean lesion length 169.8±83.3 mm; 12 lesions were de novo and severely calcified. Procedure success was defined as successful revascularization of the CTO. Technical success was placement of a guidewire beyond the distal CTO cap into the true lumen without the need for a re-entry device. All CTOs were successfully crossed using the TruePath, but 3 subintimal recanalizations required the use of a re-entry device (77% technical success). Eight lesions were stented, while the remaining were treated with balloon angioplasty and/or atherectomy. Average fluoroscopy time was 41.1±18.3 minutes, during which a mean 200.0±46.2 mL of iodinated contrast were used (radiation dose area product 211.2±202.6 Gy*cm(2)). There were no periprocedural complications. Significant improvement was seen in the 6-month ankle-brachial index (p=0.018) and Rutherford class (p=0.019). The 6-month clinically indicated target vessel revascularization rate was 8%. TruePath facilitated successful crossing of infrainguinal CTOs following an unsuccessful guidewire recanalization, with significant improvement in symptoms and no complications.

Blunt Microdissection for Endovascular Treatment of Infrainguinal Chronic Total Occlusions

To present a systematic safety evaluation of the CrossBoss blunt microdissection catheter for crossing peripheral chronic total occlusions (CTOs). Between July 2010 and July 2011, 15 patients (all men; mean age 60.7±9.1 years) underwent endovascular treatment of 17 infrainguinal CTOs that were resistant to guidewire passage, so the blunt microdissection catheter was employed to recanalize the artery. Fourteen lesions were de novo and 3 were in-stent restenoses. Sixteen lesions were in the superficial femoral artery; 8 of 17 CTOs were TASC II type D. Extensive calcification was present in 12 lesions. Mean lesion length was 182.9±66.2 mm (range 57-296). Procedural success was 100% and successful crossing without the use of a re-entry device (technical success) was achieved in 15 cases. Twelve lesions were stented. Average fluoroscopy time was 36.5±21.2 minutes (143.8±76.9 Gy*cm (2) radiaton dose area product), during which a mean 172.1±62.2 mL of iodinated contrast were used. Two patients had access site hematomas that were treated conservatively, and there was no perforation, distal embolization, amputation, or need for urgent revascularization. During the mean follow-up of 11.4±0.1 months, 1 patient died, and none required an amputation or surgical revascularization. There was a significant improvement in ankle-brachial index (0.6±0.1 to 0.8±0.2, p=0.001) and symptoms as assessed by Rutherford class at 1 year. Four of 17 limbs required secondary revascularization procedures within 1 year. The CrossBoss blunt microdissection catheter facilitated successful crossing of CTOs in patients with infrainguinal lesions following unsuccessful guidewire crossing, with an acceptably low rate of periprocedural complications and significant improvement in symptoms.

Ocelot catheter for the recanalization of lower extremity arterial chronic total occlusion

Peripheral arterial disease (PAD) is a growing clinical condition affecting more than 10 million patients in the United States and it is responsible for more than 120,000 amputations annually. The presence of chronic total occlusions (CTO) increases the complexity of endovascular procedures and open surgery may often be the preferred approach. Despite the optimization of the CTO devices and technique, percutaneous CTO revascularization remains a challenging procedure even for experienced operators with important complication rates. The Ocelot(TM) system is a novel CTO device to use real-time optical coherence tomography (OCT) imaging guidance for the recanalization of peripheral CTOs. We review the mechanism of the Ocelot system, the initial results from the multi-center Connect-II trial and two cases of Ocelot-assisted CTO recanalization.