Late stent expansion and neointimal proliferation of oversized Nitinol stents in peripheral arteries

IVUS Improves Outcomes With SUPERA Stents for the Treatment of Superficial Femoral-Popliteal Artery Disease

BACKGROUND

Nitinol interwoven bare metal stents represent an advancement in stent technology; however, nominal deployment remains an area of focus. Intravascular ultrasound (IVUS) has been shown to improve outcomes in both the coronary and peripheral vasculature by providing the operator with greater vessel detail; however, the use of adjunctive IVUS with nitinol bare metal stents has not been widely studied. This studies aims to determine the effect of IVUS when used adjunctively with nitinol interwoven bare metal stents in the management of femoropopliteal lesions.

DESIGN

Retrospective study.

METHODS

This study included a cohort of 200 consecutive patients with peripheral artery disease. All patients were treated with ≥1 Supera bare metal stent, and 91 received adjunctive IVUS imaging prior to stent deployment. Deployment conditions of nominal, compressed, and elongated were measured, and the primary clinical outcomes included target lesion reintervention, amputation, and mortality. This study also showed that 8.3 number needed to treat (NNT) patients must be treated with IVUS to avoid an additional revascularization event.

RESULTS

The patients who received IVUS had a significantly greater number of nominally deployed stents (p<0.001). Patients who had IVUS imaging also had significantly lower reintervention rates compared with those who did not receive IVUS imaging (p=0.047).

CONCLUSION

The IVUS and angiography decreases clinically-driven target lesion reintervention and increases nominal deployment compared with angiography alone in femoropopliteal lesions treated with interwoven bare metal nitinol stents.Clinical ImpactEndovascular surgones may conisder the adjuctive use of IVUS when using the Supera stent for the treatment of infra inguinal superficial femoral artery lesions. The adjunct use of IVUS may lead to improved sizing, vessel prep, deployment, and ultiamtely reduction in CD-TLR.

CT Angiography of the Upper Extremities: Review of Acute Arterial Entities

Historically, evaluation of the upper extremity vasculature was performed using digital subtraction angiography. With the advancement of cross-sectional imaging and submillimeter isotropic data acquisition, CT angiography (CTA) has become an excellent noninvasive diagnostic tool for evaluation of the vasculature of the upper extremities. CTA allows quick evaluation of vessel patency and irregularity and achievement of the anatomic detail needed in preoperative planning. When interpreting CTA of the upper extremities, radiologists must be familiar with the normal vascular anatomy, common vascular anomalies, and pitfalls or artifacts that may mimic or mask abnormality. In this review, the authors provide an overview of the utility of CTA of the upper extremities. Also discussed are CTA techniques and the use of several newer technologies including dual-energy and photon-counting detector CT. The utility of CTA in patients with upper extremity trauma is explored, with a focus on assessing vascular injury. Other vascular abnormalities including infection, acute limb ischemia, and vasculitis are discussed. It is imperative for radiologists to be accustomed to CTA of the upper extremities in diagnosing acute vascular abnormalities and to recognize common pitfalls and mimics of these abnormalities. ©RSNA, 2025 Supplemental material is available for this article.

Preoperative Sizing to Lower In-Stent Restenosis in Peripheral Arterial Occlusive Disease

BACKGROUND

The primary treatment for lower-extremity peripheral arterial occlusive disease (PAOD) is angioplasty stenting. Its main complication is in-stent restenosis. Poor selection of stent dimensions has been identified as a factor contributing to early in-stent restenosis. The aim of this study is to determine whether the implantation of stents, selected based on arterial morphological reconstruction using a sizing software program, reduces the occurrence of in-stent restenosis. The study also aims to evaluate the potential benefits of routine preoperative sizing.

METHODS

Between January 2016 and December 2020, all patients treated for PAOD through scheduled angioplasty stenting in our department were included in the study. Using systematic preoperative computed tomography angiography, precise reconstruction and sizing were performed to select the ideal length and diameter of stents, resulting in the selection of a so-called IDEAL stent. During the procedure, the surgeon implanted either the IDEAL stent or a different one, named the ACTUAL stent, based on intraoperative data and/or availability. We compared the in-stent restenosis rate between IDEAL and ACTUAL stents.

RESULTS

There were no significant differences in the overall characteristics between the IDEAL and ACTUAL stent groups. The in-stent restenosis rate at 1 year was 13% (N = 28/212, P = 0.994) in the IDEAL group and 17% (N = 25/149, P = 0.994) in the ACTUAL group. Among the ACTUAL stents, a total of 19.6% of stents with a diameter mismatch when chosen based on arteriography showed a significantly higher restenosis rate during the first year of follow-up (P = 0.02).

CONCLUSIONS

Our study did not demonstrate a significant difference in 1-year restenosis rate between the IDEAL and the ACTUAL stent groups. It specifically revealed the significant impact of diameter selection on the intrastent restenosis rate during the first year of follow-up. Stents chosen based on arteriographic criteria, which exhibited diameter discordance, compared to the IDEAL stents group selected using sizing reconstructions, could be either oversized or undersized. This led to a significantly higher restenosis rate at 1 year postoperatively.

Treating post-angioplasty dissection in the femoropopliteal arteries using the tack endovascular system: Tack optimized balloon angioplasty II 24-month results

OBJECTIVES

The TOBA (Tack Optimized Balloon Angioplasty) II trial is a prospective, single-arm, multicenter study that investigated Tack treatment for patients with dissection after angioplasty in the superficial femoral artery and/or proximal popliteal artery. The Tack device is a nitinol-based, short (6 mm), stent-like implant with low outward force that can be deployed in a targeted fashion to treat vascular dissection. TOBA II primary results through 12 months have been published previously. This report provides follow-up safety and efficacy results through 24 months (RC).

METHODS

The TOBA II trial enrolled 213 patients with Rutherford classification 2 to 4 and a de novo or non-stented restenotic lesion in the superficial femoral artery and/or proximal popliteal artery who developed a dissection of any grade after treatment with plain balloon or drug-coated balloon (DCB) angioplasty. Participants were followed for 30 days, 6 months, 12 months, 24 months, and 36 months following the procedure. Evaluations included clinically driven target lesion revascularization (CD-TLR), ankle-brachial index, Rutherford classification, peripheral artery questionnaire, quality of life assessed by the EQ-5D-3L, and the Walking Impairment Questionnaire.

RESULTS

At enrollment, mean age was 68.2 ± 9.1 years, 70.9% were male, and 95.8% of patients were categorized as RC 2 or 3. The distribution of balloon types in the study were standard balloons: 42.3%; and drug-coated balloons: 57.7%. At 24-month follow-up, 167 patients (78.4%) had available data. The overall survival rate at 24 months was 95.4% and there were no major amputations during this time. After 24 months of follow-up, the Kaplan-Meier freedom from CD-TLR was 77.7%. Rutherford classification, ankle-brachial index, and quality of life were significantly improved compared with baseline through 24 months.

CONCLUSIONS

The TOBA II 24-month data demonstrate durable intermediate-term outcomes with the use of the Tack Endovascular System. Tack deployment was a safe and effective therapeutic option for dissection repair following angioplasty.

Prophylactic relining for bridging stent compression after thoracoabdominal endovascular aneurysm repair: Myth or reality?

BACKGROUND/OBJECTIVE

Target vessels related complications are one of the most important 'Achille's heel' of complex thoracoabdominal endovascular procedures. The aim of this report is to describe a case of spontaneous bridging stent-graft (BSG) delayed expansion in a patient treated for type III mega-aortic syndrome, associated with aberrant right subclavian artery and independent origin of the two common carotid arteries.

METHODS

The patient underwent different surgical procedures (ascending aorta replacement with carotid arteries debranching, bilateral carotid-subclavian bypass with subclavian origins embolization and TEVAR in zone 0, associated with a multibranched thoracoabdominal endograft deployment). Visceral vessels stenting was performed using balloon-expandable BSGs for celiac trunk, superior mesenteric artery and right renal artery, while for the left renal artery a 6 × 60 mm self-expandable BSG was deployed.The first follow-up (FU) by computed tomography angiography (CTA) showed a severe compression of the left renal artery BSG. Considering the challenging access to the directional branches (SAT's debranching and a tightly curve of the steerable sheath inside the branched main body), a conservative treatment was considered, performing a control CTA after 6-months.

RESULTS

Six months later, the CTA demonstrated a spontaneous expansion of the BSG, with a two-fold increase in the minimum stent diameter, excluding the need for new reinterventions such as angioplasty or BSG relining.

CONCLUSIONS

Directional branch compression is a frequent complication during BEVAR; however, in this case, it spontaneously resolved after 6 months, without the need for secondary adjunctive procedures. Further studies on predictor factors for BSG related adverse events and regarding spontaneous delayed BSGs' expansion mechanisms are needed.

Midterm Outcome of Branch Vessel Stenting for Superior Mesenteric Artery Malperfusion Complicating with Acute Aortic Dissection

Purpose

To investigate the midterm stent patency and patient prognosis after stenting for superior mesenteric artery malperfusion complicating with acute aortic dissection.

Material and Methods

Thirteen patients who underwent branch vessel stenting for superior mesenteric artery malperfusion between 2011 and 2021 in six institutions were retrospectively reviewed. By comparing pre- and postoperative computed tomography scans in the same plane, the length of the stent implanted in the superior mesenteric artery and the stent-to-vessel diameter ratio were measured. The technical and clinical success of stenting, midterm patient prognosis, and stent patency were evaluated.

Results

Superior mesenteric artery stenting was technically successful in 12 patients (92.3%). The mean length of the stents implanted in the superior mesenteric artery was 61.3 ± 39.4 mm (range, 14-127 mm). The mean proximal and distal stent-to-vessel diameter ratios were 1.02 ± 0.16 and 1.30 ± 0.42, respectively. A weak correlation was found between the length of the stents implanted in the superior mesenteric artery and the distal stent-to-vessel diameter ratio (R2 = 0.34). Two major complications occurred, one of which resulted in death within 30 days, and 12 (92.3%) were clinically successful. Of these 12 patients, no recurrent intestinal ischemia occurred during the follow-up duration (mean, 45.2 months). Partial occlusion of the stent distal edge without intestinal ischemia was observed in one patient (distal stent-to-vessel diameter ratio = 2.33) 42 months after stenting. The overall survival rate and primary stent patency rate were 84.6% and 91.7%, respectively.

Conclusions

Midterm stent patency and survival after superior mesenteric artery stenting for malperfusion were acceptable.

Removal method of a Supera interwoven stent invaginated during its implantation in endovascular procedure: a case report

BACKGROUND

Supera interwoven stents (IWS) have a unique interwoven structure; thus, precise stent placement can be challenging as they are prone to elongation, shortening, and invagination. Particularly, invagination limits long-term patency. This proposed method aims to remove invaginated IWS.

CASE PRESENTATION

A 70-year-old man presented with intermittent claudication in his left lower limb. Endovascular therapy was conventionally performed, and a 5.5 × 40 mm IWS was placed after balloon dilatation; however, invagination occurred. The invaginated IWS was successfully removed by a threading 0.014" wire through the outside of the stent strut, and a snare catheter was used to hold it in place from the inside. Then, while still in place, the 0.014" wire and snare catheter were driven into the guiding sheath.

CONCLUSIONS

This practical and easy approach to remove invaginated IWS from the body relies on the particular structural characteristics.

Liquid Drug Delivery Approaches for the Treatment of Occlusive Arterial Disease: A Systematic Review

OBJECTIVE

Local Liquid drug (LLD) delivery devices have recently emerged as a novel approach to treat peripheral arterial disease. This systemic review aims to identify and evaluate the clinical utility of the most commonly used delivery devices.

METHODS

A systemic review was performed using the Medical Subjects Heading terms of "drug delivery," "liquid," "local," and "cardiovascular disease" in PubMed, Google Scholar, and Scopus.

RESULTS

Four commonly used delivery devices were identified, including (1) the Bullfrog Micro-Infusion Device, (2) the ClearWay RX Catheter, (3) the Occlusion Perfusion Catheter, and (4) the Targeted Adjustable Pharmaceutical Administration. All have shown to successfully deliver liquid therapeutic into the target lesion and have exhibited favorable safety and efficacy profiles in preclinical and clinical trials. The LLD devices have the ability to treat very long or multiple lesions with a single device, providing a more economical option. The safety profile in LLD clinical studies is also favorable in view of recent concerns regarding adverse events with crystalline-paclitaxel-coated devices.

CONCLUSION

There is clear clinical evidence to support the concept of local liquid delivery to treat occlusive arterial disease.

CLINICAL IMPACT

The 'leave nothing behind' strategy has been at the forefront of the most recent innovations in the field of interventional cardiology and vascular interventions. Although drug coated balloons have overcome limitations associated with plain old balloon angioplasty and peripheral stents, recent safety concerns and cost considerations have impacted their usage. In this review, various liquid drug delivery devices are presented, showcasing their capabilities and success in both preclinical and clinical settings. These innovative liquid delivery devices, capable of targeted delivery and their ability to be re-used for multiple treatment sites, may provide solutions for current unmet clinical needs.

Impact of Procedural Techniques on Midterm Patency of Fluoropolymer-Based Drug-Eluting Stent Placed in the Femoropopliteal Artery

PURPOSE

To investigate the impact of compliance with recommended procedural techniques on the midterm patency of a fluoropolymer-based drug-eluting stent (FP-DES) in the femoropopliteal artery.

MATERIALS AND METHODS

This retrospective study included 200 femoropopliteal lesions (chronic limb-threatening ischemia, 59%; chronic total occlusion, 41%) in 173 patients (male, 66%; diabetes mellitus, 62%; hemodialysis, 40%) with lower extremity arterial disease who underwent intravascular ultrasound (IVUS)-guided endovascular therapy with FP-DES between January 2016 and July 2021. The primary outcome measure was restenosis, defined as a peak systolic velocity ratio of >2.4 based on the duplex US findings. The association between procedural techniques and incidence of restenosis was investigated using Cox proportional hazards regression models.

RESULTS

The 2-year cumulative incidence of restenosis was 19.5% (SD ± 3.3). Multivariate analysis revealed that noncompliance with recommended procedural techniques, such as plaque burden at the stent edge of <50%, a minimum stent area (MSA) of >12 mm2, and stent placement within the P1 segment, was independently associated with an increased risk of restenosis (hazard ratios [HRs], 3.22, 4.71, and 4.67 and P = .004, P < .001, and P < .001, respectively). The 2-year restenosis risk for procedures performed in compliance with all 3-technical criteria was 8.4% (SD ± 3.4), whereas the risks for those in compliance with 2-technical criteria or 0- or 1-technical criteria were 25.0% (SD ± 6.2) and 48.6% (SD ± 10.4), respectively. HRs relative to 3-technical criteria compliance were 3.79 (P = .007) and 11.85 (P < .001), respectively.

CONCLUSIONS

Noncompliance with recommended procedural techniques, including plaque burden at the stent edge of <50%, MSA of >12 mm2, and stent placement within the P1 segment, was significantly associated with an increased risk of 2-year restenosis after FP-DES implantation in the femoropopliteal artery.

Hemodynamic alterations of flow diverters on aneurysms at the fetal posterior communicating artery: A simulation study using CFD to compare the surpass streamline, pipeline flex, and tubridge devices

PURPOSE

Traditional flow diverters (FDs) for treating aneurysms at the fetal posterior communicating artery are unsatisfactory. Surpass Streamline is a novel FD with different mesh characteristics; however, the outcomes for such aneurysms remain unclear. This study aimed to compare hemodynamic alterations induced by Surpass Streamline, Pipeline Flex, and Tubridge devices and explore possible strategies for aneurysms at the fetal posterior communicating artery.

METHODS

Two simulated aneurysms (Case 1, Case 2) were constructed from digital subtraction angiography (DSA). The three FDs were virtually deployed, and hemodynamic analysis based on computational fluid dynamics was performed. Hemodynamic parameters, including the sac-averaged velocity magnitude (Velocity), high-flow volume (HFV), and wall shear stress (WSS), were compared between each FD and the untreated model (control). Surpass Streamline was performed in real life for two aneurysms and the clinical outcomes were collected for analysis.

RESULTS

Compared to the control, the Surpass resulted in the most significant reduction in flow. In Case 1, the Velocity, HFV, and WSS were reduced by 51.6%, 78.1%, and 64.3%, respectively. In Case 2, the Velocity, HFV, and WSS were reduced by 48.0%, 81.1%, and 65.3%, respectively. Tubridge showed slightly larger changes in hemodynamic parameters than Pipeline. In addition, our analysis suggested that metal coverage was correlated with the WSS, Velocity, and HFV. The postoperative DSA showed that the aneurysm was nearly occluded in Case 1 and decreased in Case 2.

CONCLUSION

Compared to that with the Pipeline and Tubridge, the Surpass resulted in the greatest reduction in hemodynamic parameters and might be effective for aneurysms at the fetal posterior communicating artery. Virtual FD deployment and computational fluid dynamics analysis may be used to predict the treatment outcomes.

Drug-eluting, balloon-expandable, bioresorbable vascular scaffolds reduce neointimal thickness and stenosis in an animal model of percutaneous peripheral intervention

Objective

Recanalization with balloon angioplasty and/or self-expanding stents (SES) has become the endovascular treatment of choice for symptomatic femoropopliteal occlusive disease. These strategies generate suboptimal clinical results, however, because they fail to expand the artery fully and ineffectively prevent recoil, neointimal hyperplasia, and restenosis. Balloon-expandable stents, given their greater radial force and rigid structure, represent a more effective treatment strategy, but only short lengths can be implanted safely in arteries that deform and bend with skeletal motion. The purpose of this preclinical experiment was to test the hypothesis that simultaneous implantation of a series of short, resorbable, balloon-expandable, paclitaxel-eluting scaffolds would prevent neointimal hyperplasia and stenosis compared with SES in an animal model of percutaneous femoropopliteal intervention.

Methods

We extruded 6 × 60 mm Efemoral Vascular Scaffold Systems (EVSS) from copolymers of poly-L-lactic acid, coated with paclitaxel 3 μg/mm2, crimped onto a single delivery balloon, and implanted percutaneously into the iliofemoral arteries of eight Yucatan mini-swine. We implanted 7- to 8-mm × 60 mm SES into the contralateral experimental arteries. The animals were serially imaged with contrast angiography and optical coherence tomography after 30, 90, 180, 365, and 730 days. The primary end point of this study was neointimal morphometry over time. Secondary end points included acute deformation and angiographic and optical coherence tomography-derived measurements of chronic vascular response.

Results

Over the 2-year study period, one SES was found to be completely occluded at 90 days; all EVSS were widely patent at all time points. Arteries treated with SES exhibited profound neointimal hyperplasia with in-stent stenosis. In contrast, arteries treated with EVSS exhibited only modest vascular responses and minimal stenosis. After 2 years, the mean neointimal thickness (0.45 ± 0.12 vs 1.31 ± 0.91 mm; P < .05) and area (8.41 ± 3.35 vs 21.86 ± 7.37 mm2; P < .05) were significantly decreased after EVSS implantation. By 2 years, all scaffolds in all EVSS-treated arteries had resorbed fully.

Conclusions

In this preclinical animal model of peripheral endovascular intervention, the EVSS decreased neointimal hyperplasia and stenosis significantly compared with SES, then dissolved completely between the first and second years after implantation.

In situ formation of micro/nano phase composite for 3D printing clinically relevant bioresorbable stents

With recent developments in materials engineering and additive manufacturing, the feasibility of patient-specific biomedical devices has increased substantially. Bioresorbable vascular stents/scaffolds (BVS), implants which reopen narrowed blood vessels, have seen considerable research in freeform fabrication as one such potentially customizable medical device. However, clinical requirements for stents place significant limits on manufacturing; the device must maintain the vessel's natural diameter once it has been reopened and must have sub-100 μm radial thickness to allow proper blood flow in small diameter vessels. Recent commercialization challenges for BVSs have highlighted the importance of meeting these requirements. For example, the first BVS marketed in the U.S.A., made from polylactide, had a radial thickness of 150 μm, which potentially contributed to negative side-effects and reduced efficacy. Thus, new bioresorbable materials and manufacturing strategies are required to fabricate BVSs that have sub-100 μm feature sizes that are mechanically competent and safe. In this work, we report the innovative use of a two-phase system that enables in situ formation of semicrystalline poly-l-lactic acid nanofibrous networks within a 3D printed polymeric matrix of a bioresorbable citrate-based biomaterial used for the first time in a resorbable medical device recently approved by the Food and Drug Administration. The optimized composite ink is compatible with the high-resolution micro-continuous liquid interphase production method with demonstrated smallest printable features of 80 μm. The resulting composite material has a significantly improved Young's modulus of 969.55 MPa at the fully hydrated state, a 108% improvement over the previously reported pure citrate-based biomaterial materials. We have successfully fabricated the BVS with strut thicknesses less than 100 μm and demonstrated that the stent can sustain applied vessel loading under physiological blood pressure conditions. The fabrication method can potentially be broadly applied to other biomedical devices.

Impact of chronic outward force on arterial responses of proximal and distal of long superficial femoral artery stent

BACKGROUND

Self-expanding nitinol stent (SENS) implantation is commonly oversized in the superficial femoral artery (SFA), and leads to chronic outward force (COF) and in-stent restenosis (ISR). This study aimed to investigate the impact of COF of oversizing SENS on ISR of SFA.

METHODS

In patients with implanted SENS in SFA, intimal hyperplasia especially between proximal segment and distal segment was evaluated by quantitative angiography, and the impact of COF on mid-term angiographic outcomes was investigated. In addition, porcine model with implanted SENS was used to evaluate the impact of COF on angiographic and histopathologic outcomes at 1 month. Excised stented arteries were evaluated by histopathologic analysis.

RESULTS

We analyzed 65 SENS in 61 patients with follow-up angiography at 6 months to 1 year. The baseline diameter was 6.8 ± 0.71 mm and length were 97.0 ± 33.8 mm for the SENS. The ratio of the diameter of the stent to the reference vessel was 1.3 ± 0.24 at the proximal portion and 1.53 ± 0.27 at the distal portion (P < 0.001). In the long SFA stent, stent-to-vessel ratio was significantly higher in the distal stent than in the proximal stent (1.3 ± 0.2 vs. 1.55 ± 0.25, P = 0.001). ISR incidence was higher at the distal stent (37.3% vs 52.6%, P = 0.029). All 11 pigs survived for 4 weeks after SENS implantation. The vessel diameter was 4.04 ± 0.40 mm (control group) vs 4.45 ± 0.63 mm (oversized group), and the implanted stent diameter was 5.27 ± 0.46 mm vs. 7.18 ± 0.4 mm (P = 0.001). The stent-to-vessel diameter ratio was 1.31 ± 0.12 versus 1.63 ± 0.20 (P < 0.001). After 4 weeks, restenosis % was 29.5 ± 12.9% versus 46.8 ± 21.5% (P = 0.016). The neointimal area was 5.37 ± 1.15 mm² vs. 8.53 ± 5.18 mm² (P = 0.05). The restenosis % was 39.34 ± 8.53% versus 63.97 ± 17.1% (P = 0.001).

CONCLUSIONS

COF is an important cause of restenosis in the distal portion of the SFA stent. Optimal sizing of the SFA stent is important to reduce the incidence of restenosis. Therefore, COF was an important factor of restenosis following distal SFA stenting.

Long-term results of the Japanese multicenter Viabahn trial of heparin bonded endovascular stent grafts for long and complex lesions in the superficial femoral artery

OBJECTIVE

To assess the long-term safety and efficacy of endovascular stent grafting to treat long, complex lesions in the superficial femoral artery (SFA).

METHODS

This prospective, multicenter study at 15 Japanese hospitals assessed heparin bonded stent grafts for treating long SFA lesions in patients with symptomatic peripheral arterial disease. Inclusion criteria were Rutherford category 2-5 symptoms (grade 5 without active infection), ankle-brachial index (ABI) ≤ 0.9, and SFA lesions ≥ 10 cm with ≥ 50% stenosis. The key efficacy and safety outcomes were primary-assisted patency (PAP) and adverse events through 24 months, respectively. Secondary outcomes included primary patency (PP), secondary patency, freedom from target lesion revascularization (fTLR), and VascuQOL scoring.

RESULTS

Of 103 subjects (mean age 74.2 ± 7.0 years; 82.5% male), 100 (97.1%) had intermittent claudication. Average lesion length was 21.8 ± 5.8 cm; 87 lesions (84.5%) were TASC C/D classification (65.7% chronic total occlusions). Ninety-two subjects and 61 subjects were evaluable through 24 months and 60 months, respectively. At 24 months, the Kaplan-Meier-estimated PAP rate was 85.7% (95% CI: 76.3‒91.5%), PP rate was 78.8% (95% CI: 68.8‒85.9%), and secondary patency rate was 92.0% (95% CI: 82.4-96.5%). Mean ABI was 0.64 ± 0.12 at baseline and 0.94 ± 0.19 at 24 months (P<.0001). At 24 months, fTLR was 87.2% (95% CI: 78.9-92.3%), and at 60 months, fTLR was 79.1% (95% CI: 67.9-86.8%). No device or procedure-related life- or limb-threatening critical events or acute limb ischemia cases were observed through 5 years. No stent fractures were detected in annually scheduled follow-up x-rays. Scores from the VascuQOL and Walking Impairment Questionnaire were significantly increased at 1 month through 24 months versus baseline values (P<.0001 for both). One subject was converted to open bypass through 5 years.

CONCLUSIONS

Stent grafting of long and complex SFA lesions in claudicant patients is safe and effective through long-term follow-up, with 79.1% fTLR and no study leg amputation, acute limb ischemia, or stent fractures through 5 years.

Can a self-expanding pediatric stent expand with an artery? Relationship of stent design to vascular biology

OBJECTIVES

A large-diameter, intravascular, self-expanding stent system capable of continued expansion during somatic and vascular growth was modeled with finite element analysis (FEA), manufactured and tested in an animal model.

BACKGROUND

Children can quickly outgrow intravascular stents. If a stent could expand after implantation in arteries this would be ideal for use in pediatric patients.

METHODS

Computer-aided design and FEA were used to design and manufacture large-diameter, self-expanding nitinol stents with both high and low chronic outward force (COF). Four distinct stents with similar designs but with variable lengths and strut thicknesses were manufactured. Fourteen of these stents were implanted in the abdominal aortas or iliac arteries of four juvenile swine.

RESULTS

All animals survived without complication to their designated time points of harvest (90 or 180-days), and all stents expanded to greater diameters than the adjacent non-stented artery. Luminal diameter growth was 34-49% and 20-23% for stented and non-stented segments, respectively. Histologic examination revealed variable degrees of the internal elastic lamina and/or medial disruption with a mean injury score ranging from 0.70 ± 0.56 to 1.23 ± 0.21 and low COF stents implanted in smaller arteries having a larger injury score. Inflammatory responses and stenosis formation were minimal and ranged from 0.50 ± 0.71 to 3.00 ± 0.00 and 5.52 ± 1.05% to 14.68 ± 9.12%, respectively. The stent's COF did not correlate with vessel expansion or vascular injury.

CONCLUSIONS

Self-expanding stents can mirror and even exceed somatic growth. Although longer-term testing is needed, it may be possible to custom tailor self-expanding stents to expand after arterial implantation in pediatric patients.

Impact of diabetes mellitus on the early-phase arterial healing after drug-eluting stent implantation

BACKGROUND

Early arterial healing after drug-eluting stent (DES) implantation may enable short dual-antiplatelet therapy (DAPT) strategy. The impact of diabetes mellitus (DM) on this healing has not been elucidated. We used coronary angioscopy (CAS) to compare intravascular status of DM and non-DM patients in the early phase after DES implantation.

METHODS

This study was a multicenter retrospective observational study. We analyzed CAS findings of 337 lesions from 270 patients evaluated 3-5 months after DES implantation. We divided the lesion into two groups: DM (n = 149) and non-DM (n = 188). We assessed neointimal coverage (NIC) grades (dominant, maximum and minimum), thrombus adhesion and maximum yellow color grade. NIC was graded as follows: grade 0, stent struts were not covered; grade 1, stent struts were covered by thin layer; grade 2, stent struts were buried under neointima. Yellow color was graded as grade 0, white; grade 1, light yellow; grade 2, yellow; grade 3, intensive yellow.

RESULTS

Minimum NIC grade was significantly lower in DM than in non-DM groups (p = 0.002), whereas dominant and maximum NIC grades were similar between them (p = 0.59 and p = 0.94, respectively), as were thrombus adhesion (44.3% vs. 38.8%, p = 0.32) and maximum yellow color grade (p = 0.78). A multivariate analysis demonstrated that DM was an independent predictor of minimum NIC of grade 0 (odds ratio: 2.14, 95% confidence interval: 1.19-3.86, p = 0.011).

CONCLUSIONS

DM patients showed more uncovered struts than non-DM patients 3-5 months after DES implantation, suggesting that the recent ultra-short DAPT strategy might not be easily applied to DM patients.

Drug Eluting Stent vs. Drug Coated Balloon for Native Femoropopliteal Artery Disease: A Two Centre Experience

OBJECTIVE

There have been limited clinical trials comparing drug eluting stents (DESs) and drug coated balloons (DCBs) in the treatment of femoropopliteal artery disease. This two centre retrospective and prospective cohort study sought to compare DES with DCB for the treatment of native femoropopliteal artery disease.

METHODS

A total of 288 limbs (242 patients) with native femoropopliteal artery disease were treated with DESs (Zilver PTX; 102 limbs) or DCBs (IN.PACT Admiral; 186 limbs) in two Korean endovascular centres between 19 January 2013 and 5 May 2018 and followed for a median duration of 19.6 months. The primary endpoint was primary clinical patency. Propensity score matching (PSM, 162 limbs) and inverse probability weighted (IPW) adjustment were performed to adjust for confounding baseline characteristics.

RESULTS

The DCB group had fewer lesions with Trans-Atlantic Inter-Society Consensus (TASC) II type C/D (55.9% vs. 70.6%, p = .021) or total occlusions (43.5% vs. 77.5%, p < .001) and showed shorter lesion lengths (164.2 ± 105.4 mm vs. 194.8 ± 86.8 mm, p = .009) than the DES group. After PSM, baseline clinical and lesion characteristics of the two groups were comparable except for larger reference vessel diameter in the DES group (5.4 ± 0.6 vs. 5.1 ± 0.7, p = .025). Adjunctive atherectomy was performed in 32.1% of the DCB group and in 2.5% of the DES group (p < .001). The provisional stenting was required in 14.8% of the DCB group. At two year follow up, the DCB group showed higher primary clinical patency (74.6% vs. 56.7%, hazard ratio [HR] 0.51, 95% confidence interval [CI] 0.27-0.96, p = .032) and freedom from target lesion revascularisation (85.9% vs. 71.3%, HR 0.39, 95% CI 0.17-0.89, p = .021) than the DES group. Survival from all cause death did not differ between groups (87.6% vs. 92.1%, HR 1.85, 95% CI 0.62-5.52, p = .26).

CONCLUSION

In this two centre cohort, DCBs with selective use of adjunctive atherectomy achieved more favourable outcomes than DESs for native femoropopliteal artery disease.

Influence of Self-Expanding Paclitaxel-Eluting Stent Sizing on Neointimal Hyperplasia in Superficial Femoral Artery Lesions

BACKGROUND

Although self-expanding drug-eluting stents (DES) have recently shown superior outcomes for superficial femoral artery (SFA) lesions, optimal sizing of DES diameter in SFA intervention is unclear.

METHODS AND RESULTS

A total of 40 de novo SFA lesions were randomized 1:1 to receive self-expanding DES with either a 1-mm or 2-mm larger diameter than the reference vessel diameter. Follow-up optical coherence tomography (OCT) was scheduled 6 months after DES implantation to evaluate the vascular response to the stents. Volume index (VI) was defined as volume divided by stent length. The primary endpoint was neointimal VI at 6 months. Baseline reference vessel diameter was similar between the 1-mm larger diameter group and the 2-mm larger diameter group (5.0±0.8 mm vs. 4.7±0.9 mm, P=0.35). Stent diameter was 6.3±0.6 mm in the 1-mm larger group and 7.1±0.6 mm in the 2-mm larger group (P<0.0001), and stent to reference vessel diameter ratio (SV ratio) was 1.3±0.2 and 1.5±0.2 (P<0.0001), respectively. At 6-month, neointimal VI was greater in the 2-mm larger diameter group (5.5±1.5 mm2vs. 9.6±3.4 mm2, P<0.001). The correlation analysis revealed that degree of neointimal VI was positively correlated with SV ratio (r=0.43, P<0.01).

CONCLUSIONS

Implantation of self-expanding DES with a considerably high SV ratio resulted in neointimal hyperplasia in SFA lesions.

Combining the Passeo-18 Lux Drug-Coated Balloon and the Pulsar-18 Bare Metal Stent: 12- and 24-Month Outcomes of the BIOLUX 4EVER Investigator-Initiated Trial

PURPOSE

To report the outcomes after treating stenotic or occluded femoropopliteal lesions with a drug-coated balloon (DCB) followed by the implantation of a thin-strut self-expanding bare metal stent in the BIOLUX 4EVER trial (ClinicalTrials.gov identifier NCT02211664).

MATERIALS AND METHODS

The prospective, multicenter, physician-initiated BIOLUX 4-EVER trial was conducted at 5 centers in Belgium and enrolled 120 patients (mean age 70.9±10.5 years; 79 men) with symptomatic stenotic or occluded de novo femoropopliteal lesions. A fifth of the patients had diabetes mellitus and nearly half had previous peripheral artery interventions. The lesions were a mean 83.3±49.5 mm long with a mean reference vessel diameter of 5.26±0.59 mm. Lesions were treated with a Passeo-18 Lux DCB followed by the implantation of a Pulsar-18 bare metal stent. Follow-up visits were conducted at 1, 6, 12, and 24 months postprocedure; the main outcome was primary patency at 12 months.

RESULTS

Technical success was obtained in all patients. Primary patency was observed in 89.9% of patients (95% CI 84.0% to 95.8%) at 12 months and in 83.5% at 24 months (95% CI 89.9% to 97.3%), and freedom from target lesion revascularization was 93.6% (95% CI 89.9% to 97.3%) and 86.1% (95% CI 79.9% to 92.3%), respectively. Ten patients died throughout the course of the trial (90.7% survival at 24 months), all of noncardiovascular causes. The ankle-brachial index improved from 0.68±0.09 at baseline to 0.93±0.11 and 0.93±0.12 at 12- and 24-month follow-up visits (p<0.001). An improvement of at least 1 Rutherford category was observed in 91 of 94 patients (96.8%) at 12 months and 78 of 83 patients (93.4%) at 24 months (p<0.001).

CONCLUSION

The combination of a Passeo-18 Lux DCB followed by a Pulsar-18 stent implantation produced safe and effective outcomes in the treatment of femoropopliteal lesions at up to 24 months. Adding paclitaxel to the bare nitinol stent platform by predilating with a Passeo-18 Lux DCB seems to increase efficacy at 1 and 2 years compared with the use of bare metal stents only, which were investigated in the precursor 4-EVER study.

Oversized composite braided biodegradable stents with post-dilatation for pediatric applications: mid-term results of a porcine study

Our aim was to apply a composite braided biodegradable stent (CBBS) made from poly p-dioxanone (PPDO) and polycaprolactone (PCL) as an alternative to metallic stents for the treatment of pediatric endovascular disease. CBBS properties after adjunctive post-dilatation were assessed using radial force testing. CBBS degradation was assessed using in vitro measurements. Self-expandable CBBSs (8 × 20 mm) were implanted in abdominal aortas with an oversizing ratio of 1.1-1.4 (group A, n = 12) and in common iliac arteries with an oversizing ratio >1.4 (group B, n = 12). Self-expandable metal WALLSTENTs (8 × 21 mm) were implanted in common iliac arteries with an oversizing ratio >1.4 and served as controls (group C, n = 12). Artery evaluations including angiography and histological examinations were performed at 1, 4, 6 and 12 months after stent implantation. Eight millimeter CBBSs delivered in 8Fr sheaths with adjunctive post-dilatation had properties similar to those of metallic benchmark stents and were degraded in 12 months, with mild to moderate inflammation-induced neointimal hyperplasia and vessel restenosis. Post-dilatation and oversizing are suggested when using CBBSs for polymeric strut tissue embedding and optimal wall apposition, but an overextended ratio should be avoided because of the induction of less-desirable neointimal hyperplasia. Mid-term outcomes of CBBSs with adjunctive post-dilatation were better than those of WALLSTENTs in a swine endovascular disease model.

Three-Year Efficacy and Safety of the Misago Peripheral Stent for Superficial Femoral Artery Disease: Final Results from the OSPREY Trial

PURPOSE

This study evaluated the long-term outcomes of the Misago peripheral stent trial (Terumo) for atherosclerotic lesions in the superficial femoral artery (SFA) in patients with claudication.

MATERIALS AND METHODS

This was a prospective multicenter, single-arm, clinical trial of primary stent placement for de novo cases of SFA disease conducted in the United States and Asia. The primary endpoint was freedom from clinically driven target lesion revascularization (CD-TLR) at 36 months. Secondary outcomes were ankle-brachial index (ABI), Rutherford score, Walking Impairment Questionnaire (WIQ), a quality of life survey, and rate of device fracture.

RESULTS

A total of 276 patients (64.4% male; mean age, 69.3 ± 10.1 years) were enrolled. Freedom from CD-TLR was 78.5% (95% confidence interval [CI], 73.0%-83.0%) at 24 months and 75.4% (95% CI, 69.6%-80.2%) at 36 months. Baseline ABI was 0.7 ± 0.1 and 0.98 ± 0.20 (P < .001) at 30 days after the procedure. Baseline Rutherford score was 3.6 ± 0.6 and 1.6 ± 1.0 30 at 30 days after the procedure (P < .001). Mean (and changed) ABI and Rutherford score at 36 months compared to day 30 after the procedure were, respectively, 0.91 (-0.1 ± 0.2) and 1.5 (-0.2 ± 1.1). WIQ score at baseline was 21.49 ± 26.30 and 50.51 ± 38.49 at 30 days after the procedure ( P < .001). The mean WIQ score at 2 years was 46.65 ± 37.31 (P = .12). Stent fracture rate at 36 months was 2.0% (4 of 202 patients).

CONCLUSIONS

OSPREY (Occlusive-Stenotic Peripheral Artery Revascularization Study) 36-month data demonstrated persistent freedom from CD-TLR and sustained improvement in ABI and Rutherford score with primary stent placement for SFA lesions.

Restenosis After Tack Implantation is Associated with Less Complex Patterns of Restenosis Compared to Stent Implantation

In-stent restenosis is complex, difficult to treat and has led to a ‘leave less metal behind’ approach to femoropopliteal intervention. Postangioplasty dissection often requires scaffolding to maintain patency. The Tack Endovascular System provides minimal-metal dissection repair that preserves future treatment options. Tack implants are designed to minimise the inflammation and neointimal hyperplasia that lead to in-stent restenosis. An independent angiographic core laboratory evaluated the restenosis patterns in clinically driven target lesion revascularisation (CD-TLR) during the 12 months following the index procedure in the Tack Optimized Balloon Angioplasty (TOBA) II study and compared these results to those published for nitinol stent implantation. Of the 213 patients in TOBA II, 31 (14.6%) required a CD-TLR. Of these, 28 had angiograms that were evaluated by the core laboratory, and 45.2%, 16.1%, and 29% were graded as Tosaka class I, II and III, respectively. There were no significant differences (p>0.05) in lesion length, degree of calcification or dissection class between the three groups. Tack restenotic lesion classification and analysis show a prevalence of both class I and shorter lesions relative to in-stent restenosis, which may be beneficial to long-term patient outcomes.

Impact of IVUS-Derived Vessel Size on Midterm Outcomes After Stent Implantation in Femoropopliteal Lesions

Purpose: To identify intravascular ultrasound (IVUS) findings that predict midterm stent patency in femoropopliteal (FP) lesions. Materials and Methods: A retrospective analysis was undertaken of 335 de novo FP lesions in 274 consecutive patients (mean age 72.4±8.2 years; 210 men) who had IVUS assessment before and after successful stent implantation. The mean lesion length was 13.2±9.8 cm. The primary outcome was primary patency at 24 months, defined as freedom from major adverse limb event (MALE) and in-stent restenosis (ISR). MALE was defined as major amputation or any target lesion revascularization (TLR). ISR was defined by a peak systolic velocity ratio >2.4 by duplex ultrasonography. Logistic regression analyses were performed to identify independent predictors of stent patency at 24 months; the results are presented as the odds ratio (OR) and 95% confidence interval (CI). Receiver operator characteristic (ROC) curve analysis was performed to determine the optimal threshold for prediction of stent patency at 24 months. Results: Over the 24-month follow-up, 18 (7%) patients died and 43 (15%) of 286 lesions were responsible for MALE (42 TLRs and 1 major amputation). Primary patency was estimated at 82.5% (95% CI 78.1% to 86.9%) at 12 months and 73.2% (95% CI 67.9% to 78.5%) at 24 months. Multivariable analysis revealed that longer lesion length (OR 0.89, 95% CI 0.82 to 0.97, p<0.01) was an independent predictor of declining patency, while cilostazol use (OR 3.45, 95% CI 1.10 to 10.78, p=0.03) and increasing distal reference external elastic membrane (EEM) area (OR 1.18, 95% CI 1.02 to 1.37, p=0.03) were associated with midterm stent patency. ROC curve analysis identified a distal reference EEM area of 29.0 mm² as the optimal cut-point for prediction of 24-month stent patency (area under the ROC curve 0.764). Kaplan-Meier estimates of 24-month primary patency were 83.7% (95% CI 78.3% to 89.2%) in lesions with a distal EEM area >29.0 mm² vs 53.1% (95% CI 42.9% to 63.3%) in those with a distal EEM area ≤29.0 mm² (p<0.001). Conclusion: In FP lesions with a larger distal vessel area estimated with IVUS, stent implantation can be considered as a reasonable treatment option, with the likelihood of acceptable midterm results.

Efficacy and Safety of a Newly Developed Self-Expanding Open-Cell Type Nitinol Stent for Peripheral Arteries: A Preclinical Study in Minipigs

목적

얇고 새로운 구조로 개발된 말초동맥용 자가팽창성 개방형 니티놀 스텐트의 유효성 및 안전성을 기존에 사용하는 스텐트와 비교 평가하였다.

대상과 방법

미니피그 14마리를 대상으로 실험군과 대조군 스텐트를 무작위배정 후 각 개체의 장골동맥에 대칭적으로 삽입하여 1개월(n = 5) 및 6개월(n = 9) 추적관찰하였다. 혈관조영술로 혈관 직경, 후기 내강 손실 및 협착 정도를 평가하고 조직계측학적으로 내탄력층 면적, 내강 면적, 신생 내막 면적 및 협착 정도를 분석하였다. 추적기간 중 모든 실험 개체에 대하여 매일 임상적 평가 및 식이 정도를 추적관찰하였다.

결과

모든 개체는 추적관찰 기간 중 생존하였으며 중대한 유해 반응을 보이지 않았다. 혈관조영술상 6개월 추적관찰군에서 실험군의 내강 직경이 유의하게 컸으며(p = 0.014), 후기 내강 손실이 적었고(p = 0.019), 협착 정도가 낮았다(p = 0.014). 조직학적으로 1개월 추적관찰군에서 실험군이 신생 내막 면적 및 면적 협착이 유의하게 낮았다(각, p = 0.008, p = 0.016). 6개월 추적관찰군에서는 실험군이 대조군에 비하여 내강 면적이 유의하게 넓었으며(p = 0.040), 내탄력층 면적, 신생 내막 면적 및 면적 협착이 통계적으로 유의하게 낮았다(각, p = 0.004, p = 0.008, p = 0.014).

결론

새로 개발된 말초혈관용 자가팽창성 개방형 니티놀 스텐트는 기존에 사용하는 스텐트와 비교하여 안전하며 신생 내막 증식의 정도가 적었다.

The Ever-Humbling Challenge of Peripheral Artery Disease Treatment Seen Across the Sexes

See Article Ramkumar et al

Distal Edge Stenosis After Stent Placement for Isolated Superior Mesenteric Artery Dissection: Mechanisms and Risk Factor Analysis

PURPOSE

To analyze factors potentially associated with the occurrence of distal edge stenosis after stent placement for isolated superior mesenteric artery dissection (ISMAD).

MATERIALS AND METHODS

Cases of consecutive patients who were diagnosed with spontaneous ISMAD between February 2010 and July 2018 were retrospectively identified. Of the 123 cases identified, 45 patients (42 men; three women) underwent endovascular stent placement and were included in the study. Univariate and multivariate analyses were used to assess factors potentially associated with distal edge stenosis.

RESULTS

The technical success rate among study patients was 100%. During 26.7 ± 17.3 months of follow-up, CT angiography demonstrated good distal edge patency in 25 patients (55.6%) and evidence of distal edge stenosis in 20 patients (44.4%). In univariate analysis, stent length (odds radio [OR] 1.03; 95% confidence interval [CI] 1.01, 1.06; P = .02), stent-to-vessel (S/V) diameter ratio (OR 2.27; 95% CI 1.35, 3.82; P < .01), and angulation at the distal edge (OR 1.05; 95% CI 1.00, 1.10; P =.03) were significantly associated with distal edge stenosis; only S/V diameter ratio (OR 3.36; 95% CI 1.41, 7.99; P < .01) and angulation at the distal edge (OR 1.12; 95% CI 1.01, 1.23; P =.03) retained this significance in multivariate analysis.

CONCLUSIONS

Distal edge stenosis after stent placement for ISMAD is common. S/V diameter ratio and angulation at the distal edge are independent risk factors for distal edge stenosis in patients with ISMAD who undergo stent placement.

Nanoglass-based balloon expandable stents

Here, a prototypical metallic nanoglass is proposed as a new alloy for balloon expandable stents. Traditionally, the stainless steel SS 316L alloy has been used as a preferred material for this application due to its proper combination of mechanical properties, corrosion resistance, and biocompatibility. Recently, metallic glasses (MGs) have been considered as promising materials for biodevice applications. MGs often display outstanding mechanical properties superior to those of conventional metallic alloys and overcome some of the weaknesses of SS 316L, such as radiopacity, stainless steel allergy, and thrombosis-induced restenosis. However, commonly used monolithic MGs, which have an amorphous homogeneous microstructure, suffer from lack of ductility that is necessary for deployment of balloon expandable stents. In contrast, nanoglasses, that is, amorphous alloys with heterogeneous microstructure, exhibit enhanced ductility which makes them promising materials for balloon expandable stents. We evaluate the feasibility of a prototypical Zr₆₄ Cu₃₆ nanoglass with a grain size of 5 nm for balloon expandable stents by performing finite element method modeling of the stent deployment process in a coronary artery. We consider the BX-Velocity stent design and the nanoglass mechanical properties calculated from atomistic simulations. The results suggest that nanoglasses are suitable materials for balloon expandable stent applications. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:73-79, 2020.

IN.PACT™ Admiral™ drug-coated balloons in peripheral artery disease: current perspectives

Endovascular therapy has evolved as a main treatment option especially in patients with short (<25 cm) femoropopliteal lesion. The latest guideline recommends the use of drug-eluting devices (both drug-coated balloons [DCBs] and drug-eluting stents) in short femoro-popliteal lesions as class IIb recommendation. DCB usage is also recommended for in-stent restenosis lesions (class IIb). DCBs are a more attractive treatment option because the lack of metal prosthesis allows for more flexibility in future treatment options including the option of treating nonstenting zones, previously DCB-treated zones with DCBs again. The IN.PACT™ Admiral™ DCB has shown promising clinical performance in several randomized control trials and global registries, and is currently the market DCB leader for the treatment of femoropopliteal lesions with more than 200,000 patients treated thus far. Currently, more than 10 DCBs have received Conformité Européene mark for the treatment of femoropopliteal atherosclerotic disease. Three of these (including IN.PACT Admiral DCBs) have also received Food and Drug Administration approval in the USA. However, some Conformité Européene-marked DCBs have failed to show consistent results in their clinical studies suggesting all DCBs are not created equal. Each DCB is unique (ie, drug type, drug dose, crystallinity, and excipient) with different clinical outcomes. In the current review, we will focus on the preclinical and clinical results of not only IN.PACT Admiral DCB, but also the other currently available DCBs.

Different Vascular Responses to a Bare Nitinol Stent in Porcine Femoral and Femoropopliteal Arteries

Nitinol stents are widely used for the treatment of peripheral arterial diseases in lower extremity arteries and have shown different clinical outcomes depending on implanted arterial segments. We aimed to compare histopathological responses to nitinol stents in femoral artery (FA) with those in femoropopliteal artery (FPA), which is markedly bended during knee flexion. A single nitinol stent was implanted in FA and FPA of 21 domestic swine. The stented vessels were angiographically assessed and then harvested for histopathology at 1 and 3 months after implantation. Angiographic late lumen loss was significantly greater in FPA than in FA at 3 months. Neointimal area decreased in FA and increased in FPA from 1 to 3 months. Compared with FA, peri-strut area of FPA showed more pronounced hemorrhage and fibrin deposition at 1 month and angiogenesis and inflammation at 1 and 3 months. Injury to internal elastic lamina or media was minimal in both FA and FPA at both time points. In conclusion, vascular responses to nitinol stents were different between FA and FPA with respect to time course of neointimal formation and progress of healing, suggesting that repetitive interaction between stent and vessel wall during dynamic vessel motion affected vascular responses.

Stent Protrusion >20 mm Into the Aorta: A New Predictor for Restenosis After Kissing Stent Reconstruction of the Aortoiliac Bifurcation

Purpose: To determine the long-term patency of aortoiliac kissing stents and to identify predisposing factors for the development of in-stent restenosis (ISR). Methods: A retrospective analysis was conducted of 105 patients (median age 60.9 years; 64 women) with symptomatic aortoiliac occlusive disease who had kissing stents implanted between 2001 and 2015. The indication for kissing stents was severe claudication in 91 (86.7%) patients and critical limb ischemia in 14 (13.3%). Lesions were TASC A in 52 (49.5%), B in 29 (27.6%), C in 4 (3.8%), and D in 20 (19%) patients. Twenty-five (23.8%) patients had heavily calcified lesions. In all, 210 stents were deployed [180 (85.7%) self-expanding and 30 (14.3%) balloon-expandable]. Follow-up included clinical evaluation, ankle-brachial index measurement, and duplex ultrasonography. Results: The median follow-up was 45 months. The primary patency rates were 93%, 86%, and 77% at 12, 24, and 60 months, respectively. Significant ISR developed in 23 (21.9%) patients (12 unilateral and 11 bilateral). Univariate Cox regression analysis revealed older age [hazard ratio (HR) 0.5, 95% confidence interval (CI) 0.31 to 0.81, p=0.004] and larger aortic diameter (HR 0.42, 95% CI 0.25 to 0.7, p<0.001) to be variables favoring long-term patency, while a longer aortic stent segment (HR 1.56, 95% CI 1.16 to 2.09, p=0.003) and a larger discrepancy between the summed stent diameters and the aortic diameter (HR 1.64, 95% CI 1.01 to 2.65, p=0.043) were associated with ISR development. Multivariate analysis showed a longer aortic stent segment to be the only significant determinant of ISR (HR 1.44, 95% CI 1.02 to 2.01, p=0.035). Conclusion: The kissing stent technique can be performed with good long-term patency. Patients whose iliac stents protrude too far into the aorta need closer follow-up.

Drug-Coated Balloon Angioplasty in Atherosclerosis Patients With Popliteal Artery Involvement

Purpose: To investigate outcomes of drug-coated balloon (DCB) angioplasty in endovascular interventions including or restricted to the popliteal artery. Methods: A retrospective analysis was conducted of 266 patients [median age 72 years, interquartile range (IQR) 62, 78; 166 men] treated with DCB angioplasty in 281 de novo lesions including the popliteal artery between December 2011 and January 2015 at a single center. The median lesion length was 270 mm (IQR 150, 373). The study outcomes were primary patency and predictors of restenosis [reported as the hazard ratio (HR) with 95% confidence interval (CI)]. Results: The primary patency was 77.4% at a median 12.2 months (IQR 5.7, 18.8). Independent variables associated with restenosis included baseline Rutherford category (HR 1.36, 95% CI 1.05 to 1.77, p=0.02), reference vessel diameter (HR 0.77, 95% CI 0.63 to 0.95, p=0.02), dissection (HR 1.69, 95% CI 1.022.79, p=0.04), and standard nitinol stent use (HR 2.08, 95% CI 1.14 to 3.79, p=0.02). Conclusion: Outcomes after DCB angioplasty in lesions including the popliteal artery were acceptable compared with previous studies. Further investigation with long-term follow-up is needed to confirm these results.

Accuracy of pre-interventional computed tomography angiography post-processing software and extravascularly calibrated devices to determine vessel diameters: comparison with an intravascularly located calibrated catheter

Background Accurate vessel sizing might affect treatment outcome of endovascular therapy. Purpose To compare accuracy of peripheral vessel diameter measurements using pre-interventional computed tomography angiography post processing software (CTA-PPS) and extravascularly located calibrated devices used during digital subtraction angiography (DSA) with an intravascular scaled catheter (SC). Material and Methods In 33 patients (28 men, mean age = 72 ± 11 years) a SC was used during DSA of the femoro-popliteal territory. Simultaneously, one scaled radiopaque tape (SRT) was affixed to the lateral thigh, one scaled radiopaque ruler (SRR) was positioned on the angiography table. For each patient, diameters of five anatomic landmarks were measured on DSA images after calibration using different scaled devices and CTA-PPS. Diameters were compared to SC (reference) and between groups of non-obese (NOB) and obese (OB) patients. Results In total, 660 measurements were performed. Compared to the reference, SRT overestimated the diameter by 1.2% (range = -10-12, standard deviation [SD] = 4.1%, intraclass correlation coefficient [ICC] = 0.992, 95% confidence interval [CI] = 0.989-0.992, P = 0.01), the SRR and CTA-PPS underestimated it by 21.3% (range = 1-47, SD = 9.4%, ICC = 0.864, 95% CI = 0.11-0.963, P = 0.08) and 3.2% (range = 17-38, SD = 9.7%, ICC = 0.976, 95% CI = 0.964-0.983, P = 0.01), respectively. Underestimation using the SRR was greatest in the proximal superficial-femoral artery (31%) and lowest at the P2 level of the popliteal artery (15%). In the NOB group, diameter overestimation of the SRT was 0.8% (range = 4-7, SD = 4.2%, B = 0.071, 95% CI = 0.293-0.435, P = 0.08) compared to the OB group of 1.6% (range = -7-4, SD = 2.9%, B = 0.010, 95% CI = 0.474-0.454, P = 0.96). Diameter underestimation of the SRR was 17.3% (range = 13-21, SD = 3.1%, B = 0.946, 95% CI = 0.486-1.405, P = 0.002) in the NOB group, 23.3% (range = 11-36, SD = 6.6%, B = 0.870, 95% CI = 0.268-1.472, P = 0.007) in the OB group. Conclusion For calibrated measurements SRT and CTA-PPS prove accurate compared to the reference, while SRR does not. Obesity has a significant impact on underestimation of diameter if SRR is used.

Impact of nitinol stent surface processing on in-vivo nickel release and biological response

Although nitinol is widely used in percutaneous cardiovascular interventions, a causal relationship between nickel released from implanted cardiovascular devices and adverse systemic or local biological responses has not been established. The objective of this study was to investigate the relationship between nitinol surface processing, in-vivo nickel release, and biocompatibility. Nitinol stents manufactured using select surface treatments were implanted into the iliac arteries of minipigs for 6 months. Clinical chemistry profile, complete blood count, serum and urine nickel analyses were performed periodically during the implantation period. After explant, stented arteries were either digested and analyzed for local nickel concentration or fixed and sectioned for histopathological analysis of stenosis and inflammation within the artery. The results indicated that markers for liver and kidney function were not different than baseline values throughout 180 days of implantation regardless of surface finish. In addition, white blood cell, red blood cell, and platelet counts were similar to baseline values for all surface finishes. Systemic nickel concentrations in serum and urine were not significantly different between processing groups and comparable to baseline values during 180 days of implantation. However, stents with non-optimized surface finishing had significantly greater nickel levels in the surrounding artery compared to polished stents. These stents had increased stenosis with potential for local inflammation compared to polished stents. These findings demonstrate that proper polishing of nitinol surfaces can reduce in-vivo nickel release locally, which may aid in minimizing adverse inflammatory reactions and restenosis.

STATEMENT OF SIGNIFICANCE

Nitinol is a commonly used material in cardiovascular medical devices. However, relationships between nitinol surface finishing, in-vivo metal ion release, and adverse biological responses have yet to be established. We addressed this knowledge gap by implanting single and overlapped nitinol stents with different surface finishes to assess systemic impact on minipigs (i.e. serum and urine nickel levels, liver and kidney function, immune and blood count) over the 6 month implantation period. In addition, nickel levels and histopathology in stented arteries were analyzed on explant to determine relationships between surface processing and local adverse tissue reactions. The findings presented here highlight the importance of surface processing on in-vivo nickel release and subsequent impact on local biological response for nitinol implants.

Impact of Stent-to-Vessel Diameter Ratio on Restenosis in the Superficial Femoral Artery After Endovascular Therapy

BACKGROUND

Although stent-to-vessel (S/V) diameter ratio has been described as a restenotic factor after superficial femoral artery (SFA) stenting, the reference vessel diameter is commonly measured distally at a healthy site. It remains unclear whether S/V ratio assessed at the lesion site would be more predictive than that assessed distally at a healthy site.

METHODS AND RESULTS

A total of 117 patients (mean age, 73±7 years; 74% male) who underwent successful nitinol stent implantation in SFA lesions (mean lesion length, 172±104 mm) on intravascular ultrasound (IVUS) were retrospectively analyzed. S/V ratio at the proximal and distal healthy site, and at the smallest lesion site, was evaluated on IVUS. One-year restenosis predictors were evaluated on multivariate analysis. Mean S/V diameter ratio on IVUS at proximal and distal healthy sites, and at the lesion site, was 0.98±0.11, 1.02±0.11 and 1.15±0.16, respectively. One-year primary patency was 77%. On multivariate analysis, lesion length (OR, 1.06 per 10-mm increment; P=0.046) and S/V ratio measured at the lesion site (OR, 1.34 per 0.1 increment; P=0.032), but not that at the distal healthy site (OR, 1.05 per 0.1 increment; P=0.705), were significantly associated with 1-year restenosis.

CONCLUSIONS

S/V ratio assessed on IVUS at the lesion site, but not at the distal healthy site, was independently associated with 1-year restenosis after SFA stenting.

A Critical Review on Metallic Glasses as Structural Materials for Cardiovascular Stent Applications

Functional and mechanical properties of novel biomaterials must be carefully evaluated to guarantee long-term biocompatibility and structural integrity of implantable medical devices. Owing to the combination of metallic bonding and amorphous structure, metallic glasses (MGs) exhibit extraordinary properties superior to conventional crystalline metallic alloys, placing them at the frontier of biomaterials research. MGs have potential to improve corrosion resistance, biocompatibility, strength, and longevity of biomedical implants, and hence are promising materials for cardiovascular stent applications. Nevertheless, while functional properties and biocompatibility of MGs have been widely investigated and validated, a solid understanding of their mechanical performance during different stages in stent applications is still scarce. In this review, we provide a brief, yet comprehensive account on the general aspects of MGs regarding their formation, processing, structure, mechanical, and chemical properties. More specifically, we focus on the additive manufacturing (AM) of MGs, their outstanding high strength and resilience, and their fatigue properties. The interconnection between processing, structure and mechanical behaviour of MGs is highlighted. We further review the main categories of cardiovascular stents, the required mechanical properties of each category, and the conventional materials have been using to address these requirements. Then, we bridge between the mechanical requirements of stents, structural properties of MGs, and the corresponding stent design caveats. In particular, we discuss our recent findings on the feasibility of using MGs in self-expandable stents where our results show that a metallic glass based aortic stent can be crimped without mechanical failure. We further justify the safe deployment of this stent in human descending aorta. It is our intent with this review to inspire biodevice developers toward the realization of MG-based stents.

LumenRECON Guidewire: Pilot Study of a Novel, Nonimaging Technology for Accurate Vessel Sizing and Delivery of Therapy in Femoropopliteal Disease

BACKGROUND

Proper vessel sizing during endovascular interventions is crucial to avoid adverse procedural and clinical outcomes. LumenRECON (LR) is a novel, nonimaging, 0.035-inch wire-based technology that uses the physics-based principle of Ohm's law to provide a simple, real-time luminal size while also providing a platform for therapy delivery. This study evaluated the accuracy, reliability, and safety of the LR system in patients presenting for a femoropopliteal artery intervention.

METHODS AND RESULTS

This multicenter, prospective pilot study of 24 patients presenting for peripheral intervention compared LR measurements of femoropopliteal artery size to angiographic visual estimation, duplex ultrasound, quantitative angiography, and intravascular ultrasound. The primary effectiveness and safety end point was comparison against core laboratory adjudicated intravascular ultrasound values and major adverse events, respectively. Additional preclinical studies were also performed in vitro and in vivo in swine to determine the accuracy of the LR guidewire system. No intra- or postprocedure device-related adverse events occurred. A balloon or stent was successfully delivered in 12 patients (50%) over the LR wire. Differences in repeatability between successive LR measurements was 2.5±0.40% (R²=0.96) with no significant bias. Differences in measurements of LR to other modalities were 0.5±1.7%, 5.0±1.8%, -1.5±2.0%, and 6.8±3.4% for intravascular ultrasound core laboratory, quantitative angiography, angiographic, and duplex ultrasound, respectively.

CONCLUSIONS

This study demonstrates that through a physics-based principle, LR provides a real-time, safe, reproducible, and accurate vessel size of the femoropopliteal artery during intervention and can additionally serve as a conduit for therapy delivery over its wire-based platform.

Self-expanding nitinol stents of high versus low chronic outward force in de novo femoropopliteal occlusive arterial lesions (BIOFLEX-COF trial): study protocol for a randomized controlled trial

Background

Self-expanding nitinol stents must be oversized at least by a minimal amount to ensure contact with the vessel wall and prevent migration. Once the stent is deployed it exerts a continuous force upon the vascular wall, termed chronic outward force (COF). Animal studies have found an increased neointimal hyperplasia in stents with high oversizing and thus high COF. Data about correlation between COF and neointimal hyperplasia in humans are currently lacking. The objective of the BIOFLEX-COF trial is to prospectively investigate differences in formation of intimal hyperplasia at 1 and 2 years after implantation of nitinol stents with high versus low COF in de novo femoropopliteal occlusive arterial lesions.

Methods

The BIOFLEX-COF trial is a prospective, quantitative, randomized study. Eighty subjects with symptomatic peripheral arterial lesions eligible for endovascular stent implantation will be enrolled and randomly assigned to either a high COF group (LifeStent Flexstar, Bard Peripheral Vascular Inc., Tempe, AZ, USA) or low COF group (Pulsar, Biotronik AG, Bülach, Switzerland) using an online randomization program to generate a random 1:1 group allocation (block randomization). After implantation and dilatation, COF at every 2 mm along the stent axis will be calculated from the actual stent diameter versus its nominal diameter.

There will be two follow-up evaluations at 12 and 24 months. Primary endpoint is the amount of in-stent neointima at 1 year, assessed by contrast-enhanced CT angiography (CTA). In the control examinations, stent diameter and true lumen diameter will be measured on DICOM images every 2 mm along the stent axis to quantify the relative amount of in-stent restenosis.

Secondary objectives are the amount of in-stent neointima at 2 years, device- and procedure-related adverse events and target lesion revascularization (TLR) rate.

The scheduled time for recruitment is 2 years. Recruitment is expected to be complete in October 2017.

Discussion

This trial is the first to prospectively investigate the influence of COF on stent patency. If successful, the results will aid in a more precise selection of stent type and size in a given target vessel.

The present study is challenging in that it compares two different self-expanding nitinol stents head-to-head against each other. To optimize the power of this study, traditional binary outcome parameters such as TLR and restenosis at Doppler ultrasound were dropped as primary endpoints. Instead, the amount of neointima inside the stent accessed by CTA was selected as (continuous) outcome parameter.

Trial registration

ClinicalTrials.gov Identifier: NCT03097679. Date of registration: 14 March 2017 (retrospectively registered).

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2338-0) contains supplementary material, which is available to authorized users.

The effects of surface processing on in-vivo corrosion of Nitinol stents in a porcine model

A major limitation with current assessments of corrosion in metallic medical devices is the lack of correlation between in-vitro and in-vivo corrosion performance. Therefore, the objective of this study was to elucidate the relationship between pitting corrosion measured by breakdown potentials (E_b) in ASTM F2129 testing and corrosion resistance in-vivo. Four groups of Nitinol stents were manufactured using different processing methods to create unique surface properties. The stents were implanted into iliac arteries of minipigs for six months and explanted for corrosion analysis. Scanning electron microscopy and energy dispersive X-ray spectrometry analyses indicated that stents with a thick complex thermal oxide (420nm) and high corrosion resistance in-vitro (E_b=975±94mV) were free from detectable corrosion in-vivo and exhibited no changes in Ni/Ti ratio when compared to non-implanted controls. This result was also found in mechanically polished stents with a thin native oxide (4nm; E_b=767±226mV). In contrast, stents with a moderately thick thermal oxide (130nm) and low corrosion resistance in-vitro (E_b=111±63mV) possessed corrosion with associated surface microcracks in-vivo. In addition, Ni/Ti ratios in corroded regions were significantly lower compared to non-corroded adjacent areas on explanted stents. When stents were minimally processed (i.e. retained native tube oxide from the drawing process), a thick thermal oxide was present (399nm) with low in-vitro corrosion resistance (E_b=68±29mV) resulting in extensive in-vivo pitting. These findings demonstrate that functional corrosion testing combined with a detailed understanding of the surface characteristics of a Nitinol medical device can provide insight into in-vivo corrosion resistance.

STATEMENT OF SIGNIFICANCE

Nitinol is a commonly used material in the medical device industry. However, correlations between surface processing of nitinol and in-vivo corrosion has yet to be established. Elucidating the link between in-vivo corrosion and pre-clinical characterization can aid in improved prediction of clinical safety and performance of nitinol devices. We addressed this knowledge gap by fabricating nitinol stents to possess distinct surface properties and evaluating their corrosion susceptibility both in-vitro and after six months of in-vivo exposure. Relationships between stent processing, surface characterization, corrosion bench testing, and outcomes from explanted devices are discussed. These findings highlight the importance of surface characterization in nitinol devices and provide in-vitro pitting corrosion levels that can induce in-vivo corrosion in nitinol stents.

Long-Term Results from the MAJESTIC Trial of the Eluvia Paclitaxel-Eluting Stent for Femoropopliteal Treatment: 3-Year Follow-up

PURPOSE

To report the 3-year results of the MAJESTIC first-in-human study of the Eluvia Drug-Eluting Vascular Stent System for treating femoropopliteal artery lesions.

METHODS

The prospective, single-arm, multicenter clinical trial enrolled 57 patients with symptomatic lower limb ischemia (Rutherford category 2, 3, or 4) and lesions in the superficial femoral artery or proximal popliteal artery. Mean lesion length was 70.8 ± 28.1 mm, and 46% of lesions were occluded. Efficacy measures at 2 years included primary patency, defined as duplex ultrasound peak systolic velocity ratio of ≤2.5 and the absence of target lesion revascularization (TLR) or bypass. Safety monitoring through 3 years included adverse events and TLR.

RESULTS

Primary patency was estimated as 83.5% (Kaplan-Meier analysis) at 24 months, and 90.6% (48/53) of patients maintained an improvement in Rutherford class. At 36 months, the Kaplan-Meier estimate of freedom from TLR was 85.3%. No stent fractures were identified, and no major target limb amputations occurred.

CONCLUSION

MAJESTIC results demonstrated long-term treatment durability among patients whose femoropopliteal arteries were treated with the paclitaxel-eluting Eluvia stent.

LEVEL OF EVIDENCE

Level 2b, cohort study.

Diagnosis, classification, and treatment of femoropopliteal artery in-stent restenosis

In-stent restenosis is a pervasive challenge to the durability of stenting for the treatment of lower extremity ischemia. There is considerable controversy about the criteria for diagnosis, indications for treatment, and preferred algorithm for addressing in-stent restenosis. This evidence summary seeks to review existing information on strategies for the treatment of this difficult problem.

Percutaneous Therapies for Peripheral Artery Disease

Percutaneous therapies for peripheral artery disease continue to evolve with new techniques and devices. Although guidelines-recommended therapies have impacted cardiovascular morbidity and mortality, endovascular interventions have been shown to reduce limb pain, improve quality of life, and prolong walking distance for those with claudication and to reduce amputation rates among those with critical limb ischemia. Novel devices such as drug-eluting stents and drug-coated balloons have improved patency for moderate-length lesions, whereas others allow treatment of heavily calcified and tortuous segments. New adjunctive devices to cross lesions and reduce or modify associated plaque have also been developed, although level 1 data regarding their efficacy are sparse. There has also been a better mechanistic understanding of lower extremity endovascular treatment using tools such as intravascular ultrasound. This information has highlighted the need for better stent size selection for the femoropopliteal arterial segments and larger balloon diameters for the tibial arteries. Moreover, a wound perfusion approach with direct in-line flow, the so-called angiosome approach, and reconstruction of the pedal loop have been advocated for improved wound healing. Technical advances such as the tibiopedal access and reentry methods have allowed crossing of lesions that were considered no option for the endovascular approach in the past. Collectively, there has been increased awareness, interest, and commitment by various specialty societies and organizations to advance the treatment of peripheral artery disease and critical limb ischemia. This is also evident by the recent coalition of 7 professional societies and organizations that represented >150 000 allied health professionals and millions of patients with peripheral artery disease at the 2015 Centers for Medicaid and Medicare Services Medicare Evidence Development and Coverage Analysis Committee meeting. The percutaneous therapies for peripheral artery disease continue to evolve with longer follow-up with randomized data and larger prospective registries. In the future, it is hopeful that we will treat the lower extremity arteries according to segments, taking into account plaque morphology, luminal versus subintimal crossing, location, and stenotic versus occlusive disease. Until then, we must identify the most cost-effective, efficacious, and safe treatment for each patient. The goal of this article is to aid the practicing vascular specialist consider the optimal choices for the management of patients with vascular disease.

Passive expansion of sub-maximally dilated transjugular intrahepatic portosystemic shunts and assessment of clinical outcomes

AIM

To assess for passive expansion of sub-maximally dilated transjugular intrahepatic portosystemic shunts (TIPS) and compare outcomes with maximally dilated TIPS.

METHODS

Polytetrafluoroethylene covered TIPS (Viatorr) from July 2002 to December 2013 were retrospectively reviewed at two hospitals in a single institution. Two hundred and thirty patients had TIPS maximally dilated to 10 mm (mTIPS), while 43 patients who were at increased risk for hepatic encephalopathy (HE), based on clinical evaluation or low pre-TIPS portosystemic gradient (PSG), had 10 mm TIPS sub-maximally dilated to 8 mm (smTIPS). Group characteristics (age, gender, Model for End-Stage Liver Disease score, post-TIPS PSG and clinical outcomes were compared between groups, including clinical success (ascites or varices), primary patency, primary assisted patency, and severe post-TIPS HE. A subset of fourteen patients with smTIPS underwent follow-up computed tomography imaging after TIPS creation, and were grouped based on time of imaging (< 6 mo and > 6 mo). Change in diameter and cross-sectional area were measured with 3D imaging software to evaluate for passive expansion.

RESULTS

Patient characteristics were similar between the smTIPS and mTIPS groups, except for pre-TIPS portosystemic gradient, which was lower in the smTIPS group (19.4 mmHg ± 6.8 vs 22.4 mmHg ± 7.1, P = 0.01). Primary patency and primary assisted patency between smTIPS and mTIPS was not significantly different (P = 0.64 and 0.55, respectively). Four of the 55 patients (7%) with smTIPS required TIPS reduction for severe refractory HE, while this occurred in 6 of the 218 patients (3%) with mTIPS (P = 0.12). For the 14 patients with follow-up computed tomography (CT) imaging, the median imaging follow-up was 373 d. There was an increase in median TIPS diameter, median percent diameter change, median area, and median percent area change in patients with CT follow-up greater than 6 mo after TIPS placement compared to follow-up within 6 mo (8.45 mm, 5.58%, 56.04 mm², and 11.48%, respectively, P = 0.01).

CONCLUSION

Passive expansion of smTIPS does occur but clinical outcomes of smTIPS and mTIPS were similar. Sub-maximal dilation can prevent complications related to over-shunting in select patients.