Permanent Stents Research Articles

Intracranial Stenting as Rescue Therapy After Failure of Mechanical Thrombectomy for Basilar Artery Occlusion: Data From the ANGEL-ACT Registry.

Background and Purpose: Studies on rescue therapy for acute posterior circulation stroke due to basilar artery occlusion (BAO) are limited in the modern era of mechanical thrombectomy (MT). The aim of this study was to evaluate the safety and efficacy of rescue stenting (RS) following MT failure in patients with BAO.Methods: Data were collected from the Endovascular Treatment Key Technique and Emergency Work Flow Improvement of Acute Ischemic Stroke (ANGEL-ACT) prospective registry in China. Patients who underwent MT for BAO with failure of recanalization were enrolled in this study. The patients were divided into the RS and non-RS groups. Clinical and laboratory findings, procedural details, and clinical outcomes were compared between the two groups.Results: Overall, 93 patients with acute BAO were analyzed. The RS group included 81 (87.1%) patients, and the non-RS group included 12 patients. A modified treatment in cerebral infarction (mTICI) score of 2b/3 was achieved in 75 (92.6%) patients in the RS group. Compared with the non-RS group, the RS group had a significantly higher rate of successful recanalization and favorable clinical outcomes (modified Rankin Scale score at 90 days post-procedure, 0–3: 16.7 vs. 51.9%, respectively; P = 0.023) without an increase in the rate of symptomatic intracranial hemorrhage and a significantly lower mortality rate (58.3 vs. 18.5%, respectively; P = 0.006). Furthermore, the use of a glycoprotein IIb/IIIa inhibitor improved the rate of recanalization of the target artery without increasing the rate of symptomatic intracranial hemorrhage.Conclusions: Permanent stenting appears to be a feasible rescue modality when MT fails and might provide functional benefits in patients with acute ischemic stroke due to BAO.

Choledocholithiasis: Long-term follow-up in patients without stone clearance at first endoscopic retrograde cholangiopancreatography.

Complete clearance during endoscopic retrograde cholangiopancreatography (ERCP) for choledocholithiasis is not always successful and biliary stenting is commonplace. Strategies vary between temporary stent placement (TSP) with interval ERCP or permanent stent placement (PSP) and watchful waiting for recurrent biliary obstruction (RBO). This study aimed to describe outcomes in these two groups and stent patency rates in PSP. Patients with incomplete clearance at first ERCP for choledocholithiasis between May 2015 and December 2018 were identified. Clinical outcomes were obtained by retrospective interrogation of the case notes. Median follow-up duration was 41 months (interquartile range 29-51 mo). Of 1263 index ERCP, 199 (15.8%) had no stone clearance, with 53.3% receiving PSP and 46.7% undergoing TSP. The TSP group had repeat ERCP after a median of 8 weeks; 75.3% had clearance on a repeat ERCP. The PSP group was elder than the TSP group (82 y vs 72 y, P < 0.001). The rates of RBO (32.1% vs 16.1%) and emergency readmissions (32.1% vs 19.4%) were higher in the PSP group (both P < 0.05). More patients died without further biliary disease in the PSP group (39.6% vs 12.9%, P=0.001). PSP stent patency rates at 6, 12, 24, 36, and 61 months were 87.7%, 82.1%, 75.5%, 69.8% and 67.9%, respectively. Though PSP had higher RBO and emergency readmissions, two-thirds of patients either died or survived without recurrent biliary disease. Stent patency decreased fastest in the first 12 months. Criteria to guide decision-making for biliary stenting remain unclear.

Comprehensive computational analysis of the crimping procedure of PLLA BVS: effects of material viscous-plastic and temperature dependent behavior

Recently, researchers focused their attention on the use of polymeric bioresorbable vascular scaffolds (BVSs) as alternative to permanent metallic drug-eluting stents (DESs) for the treatment of atherosclerotic coronary arteries. Due to the different mechanical properties, polymeric stents, if compared to DESs, are characterized by larger strut size and specific design. It implies that during the crimping phase, BVSs undergo higher deformation and the packing of the struts, making this process potentially critical for the onset of damage. In this work, a computational study on the crimping procedure of a PLLA stent, inspired by the Absorb GT1 (Abbott Vascular) design, is performed, with the aim of evaluating how different strategies (loading steps, velocities and temperatures) can influence the results in terms of damage risk and final crimped diameter. For these simulations, an elastic-viscous-plastic model was adopted, based on experimental results, obtained from tensile testing of PLLA specimens loaded according to ad hoc experimental protocols. Furthermore, the results of these simulations were compared with those obtained by neglecting strain rate and temperature dependence in the material model (as often done in the literature), showing how this lead to significant differences in the prediction of the crimped diameter and internal stress state.

Bifunctional poly (l-lactic acid)/hydrophobic silica nanocomposite layer coated on magnesium stents for enhancing corrosion resistance and endothelial cell responses

Biodegradable magnesium (Mg)-based vascular stents can overcome the limitations of conventional permanent metallic stents, such as late in-stent restenosis and thrombosis, but still have difficulty retarding degradation while providing adequate mechanical support to the blood vessel. We incorporated silica nanoparticles surface-functionalized with hexadecyltrimethoxysilane (mSiNP) into a poly (l-lactic acid) (PLLA) coating as a physical barrier to disturb the penetration of the corrosive medium as well as a bioactive source that releases silicon ions capable of stimulating endothelial cells. The corrosion resistance and biocompatibility of this bifunctional PLLA/mSiNP nanocomposite coating were investigated using different weight ratios of mSiNP. The nanocomposite coating containing more than 10 wt% of the mSiNP (PLLA/10mSiNP and PLLA/20mSiNP) significantly delayed the corrosion of the Mg substrate and exhibited favorable endothelial cell responses, compared to the pure PLLA coating. Specifically, the calculated corrosion rates of PLLA/10mSiNP and PLLA/20mSiNP decreased by half, indicating the durability of the coating after immersion in simulated body fluid for 12 days. Based on the in vitro cellular response, the incorporation of the mSiNPs into the PLLA coating significantly improved the endothelial cell responses to the Mg substrate, showing better initial cell surface coverage, migration, and proliferation rate than those of pure PLLA. These results indicate that the PLLA/mSiNP nanocomposite coatings have significant potential to improve the corrosion resistance and vascular compatibility of biodegradable Mg-based vascular stents.

Combination of temporary bridging device (Comaneci) and permanent stenting in the treatment of unruptured wide neck bifurcation aneurysms.

The double stent-assisted techniques for the treatment of wide neck bifurcation aneurysms (WNBAs) may be more complicating than single stent-assisted or balloon-assisted coiling. The Comaneci device (Rapid Medical, Yokneam, Israel) is a new temporary bridging device developed for covering the aneurysm neck during coiling. This new design enabled us to treat unruptured WNBAs with the use of single stent-assisted coiling instead of double stent in eight patients. At the 1-year angiographic follow-up, there was no filling in any aneurysm. There was no mortality or morbidity cases related to the procedure. In this study, we are reporting our experience of using single stent-assisted coiling combined with a Comaneci device in the treatment of unruptured WNBAs.

Spontaneous Fracture of Plastic Stents: A Rare Complication of Long-Term Indwelling Transmural Endoprosthesis

AbstractPermanent indwelling transmural stents is a safe and effective strategy for prevention of recurrence of pancreatic fluid collections following successful endoscopic transmural drainage of walled-off necrosis (WON) with coexistent disconnected pancreatic duct syndrome (DPDS). Long-term studies have shown this strategy to be safe and effective with rarely reported adverse effects. In this case series, we describe three patients of successfully treated WON and DPDS presenting later with a rare complication of permanent indwelling transmural plastic stents.

Rescue permanent LVIS stenting with post-stenting angioplasty after failed mechanical thrombectomy for refractory internal carotid artery occlusion at the paraclinoid segment: two-case report

BackgroundPrevious studies indicated the effectiveness of permanent stenting when dealing with retriever-failed refractory large vascular occlusion (LVO). Variety types of stents were implanted permanently to achieve recanalization. Low-profile visualized intraluminal support (LVIS) is generally used as a supportive device for embolization of intracranial aneurysm. Its specific structural and functional characteristics contribute to its potential of treating LVO.Cases presentationA 51-year-old male was transferred to our stroke center because of conscious disturbance with the weakness of the left upper limb. The National Institute of Health Stroke Scale (NIHSS) was 24; the Glasgow Coma Scale (GCS) was 10. Digital subtraction angiography (DSA) showed that his paraclinoid segment of R-ICA was occluded due to hard clot embolization. Thrombectomy was performed 6 times, but the occlusion remained. Finally, LVIS was implanted permanently and post-dilation was performed, which successfully recanalized the artery (eTICI 2c). The post-operative NIHSS and GCS were 20 and 11, respectively, which were 10 and 14 when discharged.Another patient was a 71-year-old male who suffered weakness of left limbs. NIHSS was 15; GCS was 11. DSA confirmed that the paraclinoid segment of his R-ICA was occluded due to hard clot embolization. Totally 6 times of mechanical thrombectomy, angioplasty, and tirofiban infusion were performed, which failed to recanalize the artery. In the end, LVIS implantation with post-dilation was performed, and full recanalization was achieved (mTICI 3). The post-operative NIHSS and GCS were 9 and 15, respectively, which were 3 and 15 when discharged.ConclusionsThese 2 cases invited LVIS into the treatment of refractory occlusion due to hard clot embolization at the paraclinoid segment, and the outcomes were preferable because of the higher visibility, higher flexibility, and lower cell size of LVIS.

Endoscopic aqueductoplasty and stenting in the treatment of isolated fourth ventricle in children: 20-year institutional experience.

Endoscopic aqueductoplasty with aqueductal stenting is an effective surgical procedure for the treatment of isolated fourth ventricle (IFV). Due to the rarity of the underlying pathology, it can be considered a rare procedure that can be performed with different surgical techniques and approaches. To assess long-term functioning of permanent aqueductal stents implanted in children affected by hydrocephalus and IFV and to describe some variations of the same procedure. We reviewed retrospectively all the patients presenting at our institution in the years 1999-2019 for symptoms of isolated fourth ventricle who underwent a surgical procedure of endoscopic aqueductoplasty and/or aqueductal stent. Surgical reports, radiological images, and surgical videos were retrospectively analyzed. Thirty-three patients with symptomatic isolated fourth ventricle (IFV) underwent fifty (50) neuroendoscopic procedures in the period observed. The median age of the patients at the time of first surgery was 7 months, with 22 premature babies. In twenty-nine patients (87.8%), a precoronal approach was performed, while four patients received a suboccipital burr hole. Ten patients were never reoperated since. Twenty-three patients underwent further surgeries: a new aqueductoplasty with aqueductal stent was performed in 13 cases. The remaining 10 patients required a combination of other procedures for management of hydrocephalus. Long-term follow-up showed a permanent stent functioning rate of 87% at 2 years and 73% at 4 years, remaining stable afterwards at very long term (20 years). Endoscopic aqueductoplasty and stenting is a reliable procedure in the long-term management of isolated fourth ventricle.

Endovascular therapy in patients with large vessel occlusion due to cardioembolism versus large-artery atherosclerosis.

Background and aims:To investigate whether stroke aetiology affects outcome in patients with acute ischaemic stroke who undergo endovascular therapy.Methods:We retrospectively analysed patients from the Bernese Stroke Centre Registry (January 2010–September 2018), with acute large vessel occlusion in the anterior circulation due to cardioembolism or large-artery atherosclerosis, treated with endovascular therapy (±intravenous thrombolysis).Results:The study included 850 patients (median age 77.4 years, 49.3% female, 80.1% with cardioembolism). Compared with those with large-artery atherosclerosis, patients with cardioembolism were older, more often female, and more likely to have a history of hypercholesterolaemia, atrial fibrillation, current smoking (each p < 0.0001) and higher median National Institutes of Health Stroke Scale (NIHSS) scores on admission (p = 0.030). They were more frequently treated with stent retrievers (p = 0.007), but the median number of stent retriever attempts was lower (p = 0.016) and fewer had permanent stent placements (p ⩽ 0.004). Univariable analysis showed that patients with cardioembolism had worse 3-month survival [72.7% versus 84%, odds ratio (OR) = 0.51; p = 0.004] and modified Rankin scale (mRS) score shift (p = 0.043) and higher rates of post-interventional heart failure (33.5% versus 18.5%, OR = 2.22; p < 0.0001), but better modified thrombolysis in cerebral infarction (mTICI) score shift (p = 0.025). Excellent (mRS = 0–1) 3-month outcome, successful reperfusion (mTICI = 2b–3), symptomatic intracranial haemorrhage and Updated Charlson Comorbidity Index were similar between groups. Propensity-matched analysis found no statistically significant difference in outcome between stroke aetiology groups. Stroke aetiology was not an independent predictor of favourable mRS score shift, but lower admission NIHSS score, younger age and independence pre-stroke were (each p < 0.0001). Stroke aetiology was not an independent predictor of heart failure, but older age, admission antithrombotics and dependence pre-stroke were (each ⩽0.027). Stroke aetiology was not an independent predictor of favourable mTICI score shift, but application of stent retriever and no permanent intracranial stent placement were (each ⩽0.044).Conclusion:We suggest prospective studies to further elucidate differences in reperfusion and outcome between patients with cardioembolism and large-artery atherosclerosis.

Bioresorbable scaffolds versus permanent sirolimus-eluting stents in patients with ST-segment elevation myocardial infarction: vascular healing outcomes from the MAGSTEMI trial.

The MAGSTEMI trial showed larger endothelium-independent vasodilatation with magnesium-based bioresorbable scaffolds (MgBRS) than with sirolimus-eluting stents (SES). However, restenosis was more frequent with MgBRS. The aims of this study were to compare the healing pattern between MgBRS and SES and to describe the main causes of restenosis, as assessed by optical coherence tomography (OCT). Ninety-five consecutive patients from the randomised MAGSTEMI trial (MgBRS=48, SES=47) underwent OCT imaging at one year. Healing and bioresorption pattern were categorised into four groups: 1) indiscernible struts were observed in 33.3% versus 0% of patients (p<0.001); 2) struts integrated into the vessel wall in 22.9% versus 63.8% (p<0.001); 3) protruding struts in 37.5% versus 31.9% (p=0.568); and 4) protruding and malapposed struts in 6.3% versus 4.3% (p=0.663), respectively. MgBRS were not suitable for strut coverage analysis; SES presented with 5.6% uncovered struts. Scaffold discontinuities were observed in 10.4% and 0%, respectively (p=0.023). MgBRS presented smaller minimal lumen area (3.92±2.02 vs 6.31±1.71 mm²; p<0.001) and larger area stenosis (52.84±18.05 vs 25.02±14.58%; p<0.001). Scaffold measurements were only feasible in 50% of MgBRS, with the expansion index being smaller than in SES (0.58±0.16 vs 0.86±0.19; p<0.001). Scaffold collapse was observed in at least 50% of cases with MgBRS restenosis. Both MgBRS and SES exhibited a low degree of neointima healing, but lumen dimensions were smaller with MgBRS at one year. Although the advanced bioresorption state of MgBRS hampers the assessment of scaffold collapse, this seems to be the main mechanism of restenosis. Future generations of MgBRS should increase and prolong the radial force. NCT03234348

Preclinical investigation of neoatherosclerosis in magnesium-based bioresorbable scaffolds versus thick-strut drug-eluting stents

Neoatherosclerosis is a frequent finding after implantation of permanent metallic stents. Bioresorbable scaffolds (BRS) are considered to reduce the incidence of neoatherosclerosis owing to their dissolution and consequent vascular restoration. The aim of this study was to evaluate the formation of neoatherosclerosis between magnesium-based BRS and thick-strut metallic drug-eluting stents (DES) in a rabbit model of neoatherosclerosis and in proportion to the effect of high-dose statin medication. Fully bioresorbable magnesium scaffolds (BRS, n=45) and thick-strut permanent metallic DES of equivalent geometry and design (n=45) were implanted into the iliac arteries of New Zealand White rabbits (n=45) following endothelial balloon injury and exposure to a cholesterol diet. Endothelialisation was assessed in 12 animals after 35 days using scanning electron microscopy (SEM), showing significantly enhanced re-endothelialisation above struts in the BRS (n=13) compared to DES (n=10). Eleven (11) animals were terminated for baseline assessment after 91 days while the remaining 22 animals were randomised to receive high-dose statin treatment (3 mg/kg) or placebo. BRS-treated vessels showed a significant reduction in foam cell infiltration as a sign of early neoatherosclerosis by histology and OCT when compared to thick-strut DES-treated vessels. Statin treatment resulted in significant reduction of foam cell infiltration in BRS and DES by histology. Our findings suggest reduced neoatherosclerosis formation in magnesium-based BRS relative to thick-strut DES. High-dose statin treatment may be a promising measure to reduce neoatherosclerosis progression, both on its own and in synergy with site-targeted device-based treatment.

Thromboresistance and endothelial healing in polymer-coated versus polymer-free drug-eluting stents: Implications for short-term dual anti-platelet therapy

BackgroundShort-term dual antiplatelet therapy (DAPT) is a suitable strategy after stent implantation especially in patients at high risk for bleeding. The thromboresistant characteristics and the healing profile permanent polymer stents such as the Resolute Onyx- drug-eluting stent (DES) has never been tested against the current approved stents for short-term DAPT, the polymer free (PF) biolimus-eluting stent (PF-BES) and bare metal stents (BMS) in dedicated preclinical models. MethodsAn ex-vivo porcine arteriovenous shunt and in-vivo flow loop model were used to evaluate thromboresistance. The healing profile was assessed in the rabbit model at 28 days by confocal microscopy (CM), scanning electron microscopy (SEM) and histology. Onyx-DES was separately compared with Onyx-BMS in first experiment and PF-BES in second experiment. ResultsIn an ex-vivo shunt model, CM and SEM showed significantly less platelet adhesion for Onyx-DES relative to Onyx-BMS and PF-BES. In a flow loop model using human blood, platelet adhesion was also significantly less in Onyx-DES as compared to PF-BES and Onyx-BMS. In the healing study, Onyx-BMS showed significantly greater healing profile relative to Onyx-DES as expected, whereas Onyx-DES showed equivalent endothelial coverage by SEM and significantly less Evan's blue uptake and comparable colocalization of p120 and vascular endothelial-cadherin when compared with PF-BES. ConclusionsOnyx-DES showed qualities of thomboresistance and healing which appear to be compatible with short-term DAPT. Thromboresistance was superior to PF-BES and healing was equivalent to PF-BES in this pre-clinical study. Onyx-DES might provide advantages when considering short-term DAPT especially in patients at high risk of bleeding.

Personalized, Mechanically Strong, and Biodegradable Coronary Artery Stents via Melt Electrowriting.

Biodegradable coronary artery stents are sought-after alternatives to permanent stents. These devices are designed to degrade after the blood vessel heals, leaving behind a regenerated artery. The original generation of clinically available biodegradable stents required significantly thicker struts (∼150 μm) than nondegradable ones to ensure sufficient mechanical strength. However, these thicker struts proved to be a key contributor to the clinical failure of the stents. A current challenge lies in the fabrication of stents that possess both thin struts and adequate mechanical strength. In this contribution, we describe a method for the bottom-up, additive manufacturing of biodegradable composite stents with ultrathin fibers and superior mechanical properties compared to the base polymer. Specifically, we illustrate that melt electrowriting (MEW) can be used to 3D print composite structures with thin struts (60-80 μm) and a high degree of geometric complexity required for stenting applications. Additionally, this technology allows additive manufacture of personalized stents that are customized to a patient's unique anatomy and disease state. Furthermore, we illustrate that polycaprolactone-reduced graphene oxide nanocomposites have superior mechanical properties compared to original polycaprolactone without detriment to the material's cytocompatibility and that customizable stent-like structures can be fabricated from these materials with struts as thin as 60 μm, well below the target value for clinical use of 80 μm.

Designing Better Cardiovascular Stent Materials - A Learning Curve.

Cardiovascular stents are life-saving devices and one of the top 10 medical breakthroughs of the 21st century. Decades of research and clinical trials have taught us about the effects of material (metal or polymer), design (geometry, strut thickness, and the number of connectors), and drug-elution on vasculature mechanics, hemocompatibility, biocompatibility, and patient health. Recently developed novel bioresorbable stents are intended to overcome common issues of chronic inflammation, in-stent restenosis, and stent thrombosis associated with permanent stents, but there is still much to learn. Increased knowledge and advanced methods in material processing have led to new stent formulations aimed at improving the performance of their predecessors but often comes with potential tradeoffs. This review aims to discuss the advantages and disadvantages of stent material interactions with the host within five areas of contrasting characteristics, such as 1) metal or polymer, 2) bioresorbable or permanent, 3) drug elution or no drug elution, 4) bare or surface-modified, and 5) self-expanding or balloon-expanding perspectives, as they relate to pre-clinical and clinical outcomes and concludes with directions for future studies.

Late results of bioabsorbable scaffolds implanted in spontaneous coronary artery dissection evaluated with computed tomography coronary angiography

Abstract Background Percutaneous coronary intervention (PCI) in spontaneous coronary artery dissection (SCAD) should be reserved for cases presenting with ongoing extensive ischaemia. Bioresorbable scaffolds (BVS) have emerged as an alternative to avoid permanent stenting, an especially attractive concept for this clinical scenario. However, data of late angiographic outcome of this device in SCAD is lacking. Purpose To evaluate the long-term angiographic outcome of BVS in the setting of SCAD using computed tomography coronary angiography (CTCA) Methods In this multicentre prospective study, high-risk SCAD patients treated with BVS were scheduled for a follow-up CTCA at least 2 years from implantation date. Acquisition was performed according to the current recommendations. All the studies were analysed in a central core laboratory by an independent level 3 expert in CTCA blinded to the clinical and angiographic results. For this purpose, a dedicated software for coronary analysis was used to quantify coronary stenosis and evaluate coronary wall. Results Thirty-four BVS were implanted in 15 SCAD patients (51±12 years-old; 87% female) from 7 different centres in Spain and United Kingdom. The most common presentation was STEMI (n=9, 60%). Target vessels included 11 left anterior descending arteries (73.3%), 3 right coronary arteries (20%) and 1 left circumflex coronary artery (6.7%). One patient received target lesion revascularisation due to scaffold shrinkage in a proximal right coronary artery at 13 months. CTCA was performed 2.4±0.7 years after BVS implantation. No scaffold thrombosis or significant stenosis were detected. Patency of all scaffolds was confirmed with a median luminal area of 5.52 mm2 (IQR: 3.74–6.95) and median stenosis of 11% (IQR: 4–15%). Regarding coronary wall tissue characterization of segments with BVS, there was 32±9.3% of plaque burden and a median plaque volume of 45.3 mm3 (IQR: 26.6–61.9). The most common component of the plaque was fibrous (85±9.4%). Compared to the proximal reference segments, BVS showed more plaque burden (32.2% vs 25.3%; p=0.017) and fibrous percentage (84.7% vs 75.1%; p=0.004) whereas less fibrofatty (6 vs 4.8 mm3; p=0.007) and necrotic volume (0.4 vs 1.2 mm3; p=0.029). BVS segments showed lower absolute minimal luminal area (5.5 vs 8.9 mm2; p=0.004) and diameter (2.7 vs 3.4 mm; p=0.004) compared to the reference segment; however, non-significant differences were seen in percentage stenosis, in keeping with normal vessel tapering. Conclusions In this series of SCAD treated with BVS, scaffolds showed a satisfactory late angiographic outcome, with no significant restenosis and an excellent minimal luminal area and optimal coronary wall healing observed. Funding Acknowledgement Type of funding source: None

In vivo degradation and endothelialization of an iron bioresorbable scaffold

Detection of in vivo biodegradation is critical for development of next-generation medical devices such as bioresorbable stents or scaffolds (BRSs). In particular, it is urgent to establish a nondestructive approach to examine in vivo degradation of a new-generation coronary stent for interventional treatment based on mammal experiments; otherwise it is not available to semi-quantitatively monitor biodegradation in any clinical trial. Herein, we put forward a semi-quantitative approach to measure degradation of a sirolimus-eluting iron bioresorbable scaffold (IBS) based on optical coherence tomography (OCT) images; this approach was confirmed to be consistent with the present weight-loss measurements, which is, however, a destructive approach. The IBS was fabricated by a metal-polymer composite technique with a polylactide coating on an iron stent. The efficacy as a coronary stent of this new bioresorbable scaffold was compared with that of a permanent metal stent with the name of trade mark Xience, which has been widely used in clinic. The endothelial coverage on IBS was found to be greater than on Xience after implantation in a rabbit model; and our well-designed ultrathin stent exhibited less individual variation. We further examined degradation of the IBSs in both minipig coronary artery and rabbit abdominal aorta models. The present result indicated much faster iron degradation of IBS in the rabbit model than in the porcine model. The semi-quantitative approach to detect biodegradation of IBS and the finding of the species difference might be stimulating for fundamental investigation of biodegradable implants and clinical translation of the next-generation coronary stents.

Long-Term Follow-Up of Yearly Replaced Double Internal Stents for Extrinsic Malignant Ureteral Obstruction.

Introduction: To assess long-term outcomes of double internal stents (DIS) for the relief of external malignant ureteral obstruction (MUO). Materials and Methods: DIS (7F each; 12-month indwelling time) were inserted under general anesthesia in 62 consecutive patients (75 renal units) with MUO during 2007-2018. Surveillance was performed every 3 months, and stents were exchanged routinely every year. The need for permanent stent retrieval was considered stent failure. Maintenance of stent patency and disease-specific survival (DSS) were estimated (Kaplan-Meier). Risk factors were also assessed (univariate and multivariable Cox regression analyses). Results: The median follow-up was 27 months (interquartile range [IQR] 20-27). The most frequent tumors causing obstruction were colorectal and ovarian cancers. Six patients (10%) had stent failure caused by sepsis, creatinine elevation, or hematuria. The average time to failure was 15 months (range 1-27). A history of radiation and an estimated glomerular filtration rate (eGFR) ≤45 mL/(min/1.73 m2) were associated with stent failure (p = 0.038 and p = 0.001, respectively). Thirty-nine patients died with a median DSS of 21 months (IQR 8.6-not reached). Multivariate analysis identified eGFR ≤60 mL/(min/1.73 m2) (hazard ratio [HR] 2.1, 95% confidence interval [CI] 1.1-4.2, p = 0.02) and need for balloon dilation (HR 2.1, 95% CI 1.1-4.1, p = 0.02) as independent predictors for disease-related mortality. Twenty-six patients (42%) had stent-related complications, for example, irritative symptoms, hematuria, and infections, of whom only two failed. Conclusions: One-year indwelling DIS provide effective long-term relief of MUO and represent a simple and effective alternative to other methods of urinary diversion. They avoid the need for external tubes and contribute to improved patient satisfaction.

Impact of disconnected pancreatic duct syndrome on endoscopic ultrasound-guided drainage of pancreatic fluid collections.

Endoscopic intervention for pancreatic fluid collections (PFCs) with disconnected pancreatic duct syndrome (DPDS) has been associated with failures and increased need for additional endoscopic and non-endoscopic interventions. The primary aim of this study was to determine the outcomes of endoscopic ultrasound (EUS)-guided transmural drainage of PFCs in patients with DPDS. In patients undergoing EUS-guided drainage of PFCs from January 2013 to January 2018, demographic profiles, procedural indications and details, adverse events, outcomes, and subsequent interventions were retrospectively collected. Overall treatment success was determined by PFC resolution on follow-up imaging or stent removal without recurrence. EUS-guided drainage of PFCs was performed in 141 patients. DPDS was present in 57 of them (40 %) and walled-off necrosis was the most frequent type of PFC (55 %). DPDS was not associated with lower clinical success, increased number of repeat interventions, or increased time to PFC resolution. Patients with DPDS were more likely to be treated with permanent transmural plastic double-pigtail stents (odds ratio [OR] 6.4; 95 % confidence interval [CI] 2.5 - 16.5; P < 0.001). However, when stents were removed, DPDS was associated with increased PFC recurrence after stent removal (OR 8.0; 95 %CI 1.2 - 381.8; P = 0.04). DPDS frequently occurs in patients with PFCs but does not negatively impact successful resolution. DPDS is associated with increased PFC recurrence after stent removal.

A NOVEL STRUCTURE DESIGN OF BIODEGRADABLE ZINC ALLOY STENT AND ITS EFFECTS ON RESHAPING STENOTIC VESSEL

Biodegradable zinc alloy stents offer a prospective solution to mitigate incompatibility between artery and permanent stents. However, biodegradable stents are restricted in clinical therapy mainly because of their insufficient support for opening of stenotic vessel. As an effort to resolve this challenging problem, a novel structure of zinc alloy stent which significantly enhanced scaffold performance is proposed in this paper. Subsequently, the functionality of the new stent on reshaping vessels with 40% of stenosis was investigated in contrast with a common stent via finite element analysis. The simulation results show that radial recoiling ratio and dog-boning ratio of the new stent are decreased by 43.2% and 16.3%, respectively, compared with those of the common stent. A larger and flatter lumen is found in the plaque-vessel system deployed with the new stent. It suggests that the geometry of stent has strong influence on its mechanical performance. With strong scaffold capability and brilliant effect on reshaping stenotic vessel, the biodegradable zinc alloy stent-based novel structure is highly promised to be an alternative choice in interventional surgeries.

The coronary resorbable magnesium scaffold Magmaris®: what we have learnt (so far…).

Bioresorbable scaffold (BRS) technology provides transient vessel support with drug-delivery capability without the long-term limitations of the permanent metallic drug-eluting stents (DES). Numerous scaffolds have been developed and investigated by device manufacturers, many of which, due to device deficiencies, have fallen by the wayside. This short review will focus on the resorbable magnesium scaffold Magmaris® the only metallic bioresorbable scaffold currently available, providing an evaluation of the most up to date clinical data whilst also briefly highlighting learning points regarding the ideal patient and lesion choice and optimal implantation technique.