Stent Application Research Articles

Stent pretreatment for internal carotid artery exposed to necrotic lesions in nasopharyngeal carcinoma.

Post radiation nasopharyngeal necrosis (PRNN) invading the internal carotid artery (ICA) contributes to the death of 69.2-72.7% of PRNN patients. ICA occlusion is an effective treatment to avoid fatal bleeding, while some patients are intolerant. We present a novel method that allows for these patients without interrupting blood flow through the ICA. This study enrolled patients with PRNN-invaded ICA who were not suitable for ICA occlusion from April 2020 to November 2022. ICA stent pretreatment was performed in the 36 patients and followed the endoscopic nasopharyngectomy (ENPG) or conservative treatment for PRNN. We report the survival outcome and incidence of complications after stent implantation and compare the survival outcomes of ENPG and conservative treatment for PRNN followed by stent implantation. ICA stent pretreatment was performed in the 36 enrolled patients, among which 14 underwent ENPG, and 22 received conservative treatment. 27.8% patients died after a median follow-up of 15 months. The Kaplan-Meier estimates of overall survival were higher in the ENPG group than in the conservative treatment group. Karnofsky performance status (KPS) was significantly higher in the ENPG group than in the non-ENPG group. The innovative application of ICA stents is a promising treatment to improve outcomes in patients with PRNN invading the ICA who are unsuitable for ICA embolization, especially when followed by endoscopic surgery. However, methods to avoid postoperative cerebral ischemia and nasopharyngeal hemorrhage still require further study.

Evaluation of the association between silent ischemic lesions and stent design in carotid stenting applications

Minor ischemic events and silent ischemic lesions are more common in carotid stenting than in endarterectomy. These silent ischemic lesions are also associated with stroke risk and cognitive impairment, so it is important to understand the factors that increase the risk and develop strategies to reduce the risk. We aimed to evaluate the association between carotid stent design and silent ischemic lesion development. The files of the patients who underwent carotid stenting between January 2020 and April 2022 were scanned. Patients with diffusion MR images taken within the postoperative 24 h were included in the study, while those undergoing acute stent placement were excluded. The patients were divided into two groups: those with open-cell stents and those with closed-cell stents. A total of 65 patients, including 39 patients undergoing open-cell stenting and 26 patients undergoing closed-cell stenting, were included in the study. There was no significant difference in demographic data and vascular risk factors between the groups. New ischemic lesions were detected in 29 (74.4%) patients in the open-cell stent group and 10 (38.4%) patients in the closed-cell stent group and were significantly higher in the open-cell group. There was no significant difference between the two groups in terms of major and minor ischemic events and stent restenosis at the 3-month follow-up. The rate of new ischemic lesion development was found to be significantly higher in carotid stent procedures performed with an open-cell Protégé stent than in those performed with a closed-cell Wallstent stent.

The Effects of Thermal Treatment on the Properties and Performance of Hot Extruded Zn-Based Bioresorbable Alloy for Vascular Stenting Applications.

A new series of zinc alloys is in development for bioresorbable stent implantation to alleviate the current materials' long-term complications. Characterization and optimization of the microstructure and corresponding mechanical properties during manufacturing stages will help researchers meet the required values. In this study, the effect of hot extrusion on the Zn-Ag-Mn-Cu-Zr-Ti alloy is characterized. Additionally, thermal treatments at 390 °C for 15, 25, 40, 60, and 120 min were performed to evaluate the effect of intermetallic phase fractions on the corrosion resistance and mechanical strength. Quantitative analysis of X-ray diffraction data demonstrates that the fractions of the MnZn13, ZrZn22, and Zn0.75Ag0.15Mn0.10 intermetallic phases decrease as the thermal treatment time increases. Corrosion tests reveal a reduction in the corrosion rate of the extruded alloy after thermal treatment. The results of uniaxial compression tests and tensile tests show lower strength and higher ductility in all heat-treated conditions compared with the as-extruded condition.

Tissue Stents (Bio Stents): Search For Non- Metallic Stent And Can It Be A Game Changer In Cardiovascular Interventions?

Coronary and Vascular stenosis poses great challenge in terms of cardiovascular disease burden. Evolution of metallic stents has been key in treating Coronary Artery Disease both acute and chronic and has met challenges successfully. The last 2 decades have seen substantial reform in technology, bringing second and third generations of coronary and vascular stents mainly metallic drug-eluting stents (DES). Though stent related stenosis is big challenge, DES has met relatively much success especially during initial years. DES are found to be associated with good first-year outcomes but subsequent risk of stentrelated adverse events like thrombosis, myocardial infarction, restenosis usually appear after 1 year following implantation. The pathogenesis of these late events is related to the permanent presence of the metal stent frame or polymer within coronaries. Besides intimal hyperplasia, late stent thrombosis, and noncompliance with DAPT are still major issues leading to stent failure and often the need for reintervention. As an effective alternative to metallic stents, Bioresorbable scaffolds were developed to provide drug delivery and mechanical support functions similar to metallic drug-eluting stents (DES), followed by complete resorption with recovery of vascular structure and function, potentially improving very late clinical outcomes. A first-generation bioresorbable scaffold demonstrated to be no inferior to a contemporary metallic drug-eluting stents for overall 1-year patient-oriented and deviceoriented outcomes. However, increased rates of scaffold thrombosis and target vessel-related myocardial infarction were noted subsequently at 5 year follow up. Tissue/Bio Stents can present as a path breaking alternative approach to avoid intimal hyperplasia. They are characterised by presence of biodegradable struts with tissue mesh and complete absence of metal preventing ingrowth of the neointimal tissue into the lumen. Currently used stent materials include mainly metals and synthetic polymers. Their main limitation is lack of hemocompatibility, which can induce thrombosis and ultimately reocclusion, thus impairing the long-term performance of these devices. We are proposing use of biologically derived material to overcome this issue with the aim of enhancing the biocompatibility and the capability of this type of stents to support endothelialilzation. The aim of this article is to give a comprehensive overview of the manufacturing and applications of Tissue or Bio Stents as well as the different strategies followed for their development from the perspective of the material selection, fabrication approaches, and logical validation of the different concepts into animal and clinical trials.

Improvement of mechanical properties of Co–Cr–W–Ni alloy tube suitable for balloon-expandable stent applications through heat treatment

This study focuses on the changes in the microstructure and mechanical properties of the Co–20Cr–15W–10Ni (CCWN, mass%) alloy tube, which, with heat treatment, is used as a balloon-expandable stent. To the best of our knowledge, this is the first report on the improvement of mechanical properties by microstructure control in CCWN alloy tubes. In addition, optimized heat treatment conditions are proposed for the development of next-generation small-diameter stents. The cold-worked CCWN alloy tube for stents was statically recrystallized by heat treatment at temperatures of 1373–1473 K for holding times of 60–900 s. The recrystallized alloy tubes exhibited a microstructure with a γ(fcc)-phase matrix and an average grain size of 5.8–34.1 μm. The strength and plastic elongation increased with decreasing grain size. In the coarse-grained structure, a large plate-like ε-phase formed along the twin boundary and stacking fault. The ε-phase grew to the grain boundaries, such that large cracks could form, resulting in early fracture. In the fine-grained structure, a small ε-phase formed by strain-induced martensitic transformation was uniformly dispersed, and the formation of large cracks was suppressed, leading to high ductility. The effect of low-temperature heat treatment (LTHT) at 873 K after recrystallization depended on the grain size of the alloy tube. In the alloy tube with a grain size of >15 μm, ε(hcp)-phase formation during plastic deformation was suppressed through the decrease in stacking fault density during LTHT, which resulted in improved ductility. In contrast, in the alloy tube with a grain size of <15 μm, the amount of precipitates increased during LTHT, resulting in reduced ductility.

Effectiveness of Guiding Catheter Retrieval Balloon Technique in the Treatment of Acute Anterior Circulation Tandem Occlusion: A Retrospective Study

Tandem occlusion accounts for 10%-20% of all large vessel occlusion strokes and often yields a poor recanalization rate. The endovascular treatment of tandem lesions is still controversial. This study uses an endovascular treatment strategy, "guided catheter recovery balloon (GRB)" for the treatment of acute anterior circulation tandem occlusion. A retrospective design was adopted. The population included patients with acute tandem occlusion who received emergency GRB endovascular treatment. And the choice of stenting was made based on intraoperative radiography imaging. Recanalization was evaluated by the thrombolysis in cerebral infarction score after the operation. Three-month modified Rankin Scale follow-up results were recorded, and modified Rankin Scale ≤2 was considered favorable recovery. A total of 55 patients aged 66.9 ± 8.5years were enrolled, 37 of whom received stenting. The mean overall recanalization time was 46minutes. Fifty (90.9%) patients achieved successful recanalization with a thrombolysis in cerebral infarction score of 2b-3. At the 3-month follow-up, the number of patients with favorable functional recovery was 28 (50.9%). The presence of hypertension was correlated with a favorable recovery outcome: 82.1% of the favorable recovery population had hypertension, and 55.6% of the unfavorable outcome population had hypertension (P=0.033). There was no statistically significant association between stent application and favorable recovery outcomes (P=0.504). GRB technique showed a high recanalization rate when applied to the treatment of acute anterior circulation tandem occlusion.

Pancreatic duct stents.

Pancreatic duct stenting using endoscopy or surgery is widely used for the management of benign and malignant pancreatic diseases. Endoscopic pancreatic stents are mainly used to relieve pain caused by chronic pancreatitis and pancreas divisum, and to treat pancreatic duct disruption and stenotic pancreaticointestinal anastomosis after surgery. They are also used to prevent postendoscopic retrograde cholangiopancreatography pancreatitis and postoperative pancreatic fistula, treat pancreatic cancer, and locate radiolucent stones. Recent advances in endoscopic techniques, such as endoscopic ultrasonography and balloon enteroscopy, and newly designed stents have broadened the indications for pancreatic duct stenting. In this review we outlined the types, insertion procedures, efficacy, and complications of endoscopic pancreatic duct stent placement, and summarized the applications of pancreatic duct stents in surgery.

Multimodal effects of asymmetric coating of coronary stents by electrospinning and electrophoretic deposition

Drug-eluting stents (DESs) are drug-coated vascular implants that inhibit smooth muscle cell proliferation and limit in-stent re-stenosis. However, traditional DESs release a single drug into the blood and cannot cope with complex mechanisms in atherosclerosis and body responses. The present study aimed to develop a novel multimodal stent by fabricating asymmetric coating with electrophoretic deposition and electrospinning. Herein, we use heparin-loaded alginate (Hep/Alg) and atorvastatin calcium-loaded polyurethane (AtvCa/PU) coatings on the stent luminal and abluminal surfaces, respectively. Scanning electron microscopy (SEM) micrographs showed that the alginate coatings had uniformity and thin thickness. Meanwhile, the PU fibers were formed without beads, with an acceptable diameter and suitable mechanical properties. PU nanofiber revealed minimal degradation in a 1-month study. The release of AtvCa and Hep continued for 8 days without a significant initial burst release. None of the stent coatings were cytotoxic or hemolytic, and PU nanofibers supported the survival of human umbilical endothelial cells (HUVEC) with high adhesion and flattened morphologies. The results indicate that electrophoretic deposition and electrospinning have significant potential for achieving asymmetric coating on stents and a promising approach for dual drug release for multimodal effects in vascular stent applications.

Combinational Growth Factor and Gas Delivery for Thrombosis Prevention.

Cardiovascular stents enable the rapid re-endothelialization of endothelial cells (ECs), and the constant suppression of smooth muscle cell (SMC) proliferation has been proved to effectively prevent thrombosis. However, the development and application of such stents are still insufficient due the delayed re-endothelialization progress, as well as the poor durability of the SMC inhibition. In this paper, we developed a mussel-inspired coating with the ability for the dual delivery of both growth factor (e.g., platelet-derived growth factor, PDGF) and therapeutic gas (e.g., nitric oxide, NO) for thrombosis prevention. We firstly synthesized the mussel-inspired co-polymer (DMHM) of dopamine methacrylamide (DMA) and hydroxyethyl methacrylate (HEMA) and then coated the DMHM on 316L SS stents combined with CuII. Afterwards, we immobilized the PDGF on the DMHM-coated stent and found that the PDGF could be released in the first 3 days to enhance the recruitment, proliferation, and migration of human umbilical vein endothelial cells (HUVECs) to promote re-endothelialization. The CuII could be "sealed" in the DMHM coating, with extended durability (2 months), with the capacity for catalyzed NO generation for up to 2 months to suppress the proliferation of SMCs. Such a stent surface modification strategy could enhance the development of the cardiovascular stents for thrombosis prevention.

Dual strengthened corrosion control of biodegradable coating on magnesium alloy for vascular stent application

Recently, magnesium alloy vascular stents have aroused great attraction because of their biodegradability and good mechanical properties. However, the rapid degradation of magnesium alloy stents causes their premature collapse in clinical application. So far, there have been few magnesium alloy stent systems that achieved sufficient support time by using biodegradable coating. In this paper, a dual strengthened biodegradable coating on a AZ31b magnesium alloy stent was suggested to achieve stronger adhesion and lower water permeability. The composite coating consisted of a magnesium hydrate - magnesium fluoride (Mg(OH)2-MgF2) inorganic base layer constructed by a simple two-step solution immersion and a graphene oxide - poly(trimethylene carbonate) outer layer prepared by ultrasonic spraying. The biodegradable composite coating modified magnesium alloy exhibited an extremely low corrosion current density of 4.3 × 10−10 A·cm−2, which is five orders of magnitude lower than the unmodified magnesium alloy. In vitro immersion tests revealed that the modification can effectively reduce the corrosion rate of the magnesium alloy stent, and the modified magnesium alloy stent can support at least 8 weeks. Furthermore, in vitro biological experiment revealed the modification of the composite coating improved the biocompatibility and ensured good microenvironment for vascular repair. These results suggest that the biodegradable composite coating has great potential for application in vascular stent.

Strengthened corrosion control of biodegradable poly(trimethylene carbonate) coating on bioabsorbable Mg alloy by introducing graphene oxide

Corrosion control of bioabsorbable Mg alloy stents is an attractive topic in recent years. Biodegradable polymer modification is a potential anti-corrosion method, but cannot achieve the desired corrosion protection due to the high water permeability of biodegradable polymers. In this study, a strengthened corrosion control strategy is proposed: Graphene oxide (GO) was introduced into a poly(trimethylene carbonate) (PTMC) coating to improve its anti-corrosion performance. GO/PTMC composite coatings with different GO contents were applied to AZ31b Mg alloy surfaces, and the effect of GO content (0, 0.2, 1, 3, 6, and 10 wt%) on surface characteristics, corrosion resistance, and in vitro biosafety was investigated. The results showed that the increase of GO content in the PTMC coating (<6 wt%) could improve its corrosion resistance by prolonging the permeation path of solution. Meanwhile, the addition of GO (<6 wt%) had little negative effects on cytocompatibility and hemocompatibility. However, when the addition of GO exceeded 6 wt%, GO aggregated on the coating surface, resulting in the formation of new defects and a rapid decrease in corrosion resistance. The optimized sample (GO content: 6 wt%) had the highest impedance modulus of 8.9 × 107 Ω·cm2 at 0.1 Hz and good in vitro biocompatibility, which shows great potential for application in vascular stents.

Worldwide productivity and research trends of publications concerning stent application in acutely ruptured intracranial aneurysms: A bibliometric study.

Stenting is a common clinical practice to treat acutely ruptured intracranial aneurysm (RIA). Although multiple studies have demonstrated its long-term safety and effectiveness, there is currently a lack of bibliometric analysis on stent application in acutely RIA. This study sought to summarize the current status of research in this field and lay a foundation for further study. Related publications were searched in the Web of Science Core Collection (WoSCC) database. Data analysis and visualization were performed by R and CiteSpace software. A total of 275 publications published in English from 1997 to 2022 were included in this study. The growth of publications slowed down. The reference co-citation network identified 13 clusters with a significant network (Q = 0.7692) and convincing clustering (S = 0.9082). The research focus was acutely RIA and the application of stents during interventional procedures. The main trends of research were: (1) development of materials, and (2) safety of stent application in acutely RIA. The United States contributed the most articles, and Jianmin Liu was the most prolific author. Mayo Clinic was the leading institution in this field. Most articles were published in Interventional Neuroradiology. This study analyzed the research trends, hotspots and frontiers of stent application in acutely RIA. It is our hope that the results obtained could provide useful information to researchers to get a clearer picture about their future research directions in this field.

Use of retrograde intrarenal surgery (RIRS) compared with mini-percutaneous nephrolithotomy (mini-PCNL) in pediatric kidney stones

ObjectiveWe aimed to compare the cost-effectiveness and safety of retrograde intrarenal surgery (RIRS) and mini-percutaneous nephrolithotomy (mini-PCNL) for pediatric kidney stones management.Patients and methodsNinety pediatric patients with single or multiple renal stones 1–3 cm in diameter were collected prospectively and equally divided into two groups to undergo RIRS or mini-PCNL. The groups were compared for fluoroscopy and operative time, postoperative hospital stay time, stone-free rate (SFR), need for auxiliary procedures, and cost as well as complications.ResultsThere were no differences found between RIRS and mini-PCNL groups with regard to operative time and postoperative DJ stent application, while the mean of fluoroscopy time and postoperative hospital stay was significantly shorter in the RIRS than in the mini-PCNL group. The SFR, auxiliary treatment on residual stones, and complications were comparable. In both groups, no major (Clavien IV–V) complications were observed. The mean cost of RIRS was $1210 and $733 for the mini-PCNL.ConclusionsBoth RIRS and mini-PCNL are effective and safe treatment modalities for pediatric renal stones 10–30 mm in size. However, mini-PCNL is more cost-effective making it a viable alternative to RIRS.

Is Surgery the Only Fate of the Patient with Leriche Syndrome? Our Endovascular Therapy Results Early Follow-Up Outcomes.

In this research, we aimed to present early follow-up results of the endovascular treatment in patients with Leriche syndrome at our single center. Between October 2020 and January 2022, 14 patients with Leriche syndrome (12 men, two women) who underwent endovascular treatment at our center retrospectively were evaluated. Before the treatment, the ankle-brachial index (ABI) was found 0.50 ± 0.11 on the right leg and 0.45 ± 0.09 on the left leg. All of the patients with Leriche syndrome applied to our clinic for the first time. In five patients, the fully occluded lesion length was over 3 cm (ranging between 3.5-7.2 cm), hence they were treated with aortic and bilateral iliac bare metallic stents. Although in one patient, the aortic occluding lesion was below 3 cm; it was treated with a bare aortic and bilateral bare iliac stent application because the lesion in the aorta was too calcific. In eight patients, the lesion length was less than 3 cm, bilateral iliac metal bare stents were applied in a kissing stent way. Endovascular therapy for chronic aorto-iliac occlusive disease has an early high technical success with primary and secondary patency rates. Especially in patients with high risk factors, it may be considered as a good alternative to conventional surgery.

Corrosion, mechanical and biological properties of biodegradable WE43 alloy modified by Al ion implantation

A high-energy metal vapor vacuum arc (MEVVA) ion source was used to implant aluminum (Al) ions into the WE43 alloy (Al-WE43) at a dose of 1 × 1016 ions·cm−2, and the structural composition, mechanical properties, corrosion resistance, and biocompatibility of the alloy before and after implantation were systematically studied. The results showed that an Al2O3/Al thin film was formed on the surface of the WE43 alloy after Al ion implantation, and the dense film caused the corrosion current density (Icorr) of the alloy to decrease from 140.2 ± 9.3 to 17.9 ± 6.1 μA⋅cm−2. Nanoindentation experiments revealed that the elastic model (EIT) and nano-hardness (HIT) of the Al-WE43 alloy were significantly improved due to the surface lattice distortion caused by Al ion implantation. A diluted extract of the Al-WE43 alloy showed higher cell activity, anti-hemolysis and anti-coagulation properties than that of the WE43 alloy. In general, the Al-WE43 alloy can be considered as a promising biodegradable metallic material for cardiovascular stent applications.

S2892 A Novel Application of Double-Pigtail Plastic Stents for Endoscopic Treatment of Stenoses and Anastomotic Leaks Following Bariatric Surgery: Endoluminal Placement to Facilitate Gastrointestinal Flow

Introduction: Transmural double pigtail plastic stents (DPPS) for treatment of anastomotic leaks have shown high success rates ( >75%), while being well-tolerated and cost-effective. For example, DPPS can be endoscopically deployed across staple-line leaks following laparoscopic sleeve gastrectomy (LSG), often combined with dilation of distal sleeve stenoses or kinks. The rationale for this combination treatment is to promote internal drainage AND intraluminal flow. However, there may also be a beneficial role for endoluminal DPPS placement in the treatment of complex anastomotic leaks and luminal stenoses. We present a series of four patients with complicated post-bariatric anatomy successfully managed with endoluminal DPPS placement. Case Description/Methods: Patient 1: 50-year-old female POD5 from LSG and duodenal switch presented with symptomatic gastric sleeve stenosis. Dilation was considered too high-risk. Two 10Fr x 12cm DPPS were endoscopically placed spanning the stenosis, pylorus, and duodenal-ileal anastomosis with instant symptom relief. DPPS were removed on POD65 with continued symptom resolution. Patients 2 and 3: 67-year-old and 70-year-old females POD12 and 14, respectively, from duodenal switch with duodeno-ileal anastomotic leak and stricture. Two 7Fr x 3cm DPPS were deployed across the leak site. A third 10Fr x 3cm DPPS was placed across the anastomosis. All stents were removed on POD45 and POD65, respectively, following leak resolution. Patient 4: 34-year-old female POD3 from complex gastric bypass reversal and duodenal switch complicated by large staple line leak proximal to stenosis. A 10Fr x 3cm DPPS was placed across the leak site. A 10Fr x 9cm DPPS was placed across the gastric stenosis and duodenal-ileal anastomosis. Serial dilation of stenosis began on POD45. All stents were removed on POD95 with resolution of leak and stenosis. Discussion: Transluminal DPPS placement across anastomotic leaks is an effective, well-tolerated, and cost-effective treatment option. This case series suggests that intraluminal DPPS placement may also be clinically beneficial by promoting GI flow and ultimately diverting away from the leak site. Intraluminal DPPS can be used singly or in combination with transluminal DPPS. Applicable scenarios include newly post-operative gastric sleeve stenoses or kinks where dilation is too high-risk and duodenal anastomotic leaks with concomitant anastomotic stricture (where metal stent placement would be challenging and dilation likewise risky). (Figure)Figure 1.: a) Endoscopic image of moderate stenosis of the mid gastric sleeve POD 5 precluding safe dilation; b) two intraluminal DPPS traversing sleeve stricture with symptom resolution ; c) improved sleeve stenosis and continued symptom resolution following DPPS removal

Imaging findings in a minipig with congenital portosystemic shunt.

A 15-month-old, male minipig was presented with a clinical history of seizure activity for one year. The minipig was the smallest among the littermates and was referred due to an elevated blood ammonia level with suspected portosystemic shunt (PSS). Ultrasound and CT angiography were consistent with a congenital extrahepatic PSS. To the author's knowledge, this is the first description of a congenital extrahepatic PSS diagnosed by ultrasound and contrast-enhanced computed tomography in a minipig (pig). Partial shunt closure was performed by interventional stent application.

Role of NOS and Inflammatory Markers in the Early Restenosis After the Application of Femoral Arterial Stent.

The objective of this research was to investigate the role of inflammatory markers, including the interleukin-6 (IL-6), matrix metalloprotease 9 (MMP-9), tumor necrotic factor α (TNF-α), endothelin-1 (ET-1) and nitric oxide synthase (NOS) in the early restenosis after the application of femoral arterial stent. According to this, serum samples were collected from the patients who accepted the implantation of arterial stents due to the atherosclerotic occlusive disease in the lower extremities at the following timepoints: 24 h before implantation, 24 h, 1 month, 3 months and 6 months after implantation. With the samples, we detected the levels of IL-6, TNF-α and MMP-9 by using the enzyme-linked immunosorbent assay (ELISA) in serum, levels of ET-1 in plasma by using the non-balanced method of radioimmunity assay and the activity of NOS by using the chemical analysis. Results showed that during the 6-month follow-up, 15 patients (15.31%) reported restenosis; at postoperative 24 h, the level of IL-6 in the restenosis group was much lower than that of the non-restenosis group (P < 0.05), while the level of MMP-9 was higher than that of the non-restenosis group (P < 0.01); besides, at postoperative 24 h, 1, 3, and 6 months after the operation, the average level of ET-1 in the restenosis group was higher than that in the non-restenosis group (P < 0.05 or 0.01). In the restenosis group, the level of NOS in the serum of patients after the implantation of the stent decreased evidently, which was rescued by the treatment of atorvastatin in a dose-dependent manner (P < 0.05). In conclusion, at postoperative 24 h, the levels of IL-6 and MMP-9 increased, while the level of NOS decreased, and the level of ET-1 in the plasma of restenosis patients keeps higher than the baseline.

Mechanical properties and biocorrosion behaviour of as-cast Zn-xCu-Sr alloys for cardiovascular bioabsorbable devices

ABSTRACT In this study, the mechanical and biocorrosion behavior of as-cast Zn-xCu-0.1Sr (x = 1, 2, and 3wt%) alloys for potential application was studied. The microstructure, mechanical properties, and in vitro degradation of Zn-xCu-0.1Sr alloys were investigated. The results show that as Cu content increased from 1.0 to 3.0wt%, the number of CuZn5 phases increased and the average grain size of CuZn5 phases increased from 6.96 μm to 10.92 μm. The 2wt% addition of Cu resulted in the best mechanical properties with 129.4 MPa in ultimate tensile strength and 108.4 MPa in yield strength. Furthermore, the higher corrosion rate was experienced in the alloys with higher Cu content after immersion. Zn-xCu-0.1Sr alloys all presented appropriate in vitro degradation rates in a basically uniform degradation mode. The strength, ductility and biocorrosion property exhibited by the Zn-2Cu-0.1Sr alloy compositions make it a promising candidate for cardiovascular stent applications.

A promoting nitric oxide‐releasing coating containing copper ion on ZE21B alloy for potential vascular stent application

Magnesium-based biodegradable metals as cardiovascular stents have shown a lot of excellent performance, which have been used to treat coronary artery diseases. However, the excessive degradation rate, imperfect biocompatibility and delayed re-endothelialization still lead to a considerable challenge for its application. In this work, to overcome these shortcomings, a compound of catalyzing nitric oxide (NO) generation containing copper ions (Cu2+) and hyaluronic acid (HA), an important component of the extracellular matrix, were covalently immobilized on a hydrofluoric acid (HF)-pretreated ZE21B alloy via amination layer for improving its corrosion resistance and endothelialization. Specifically, the Cu2+chelated firmly with a cyclen 1,4,7,10-tetraazacyclododecane-N, N′, N″, N″′- tetraacetic acid (DOTA) could form a stability of hybrid coating, avoiding the explosion of Cu2+. The chelated Cu2+enabled the catalytic generation of NO and promoted the adhesion and proliferation of endothelial cells (ECs) in vascular micro-environment. In this case, the synergistic effect of NO-generation and endothelial glycocalyx molecules of HA lead to efficient ECs promotion and smooth muscle cells (SMCs) inhibition. Meanwhile, the blood compatibility also had achieved a marked improvement. Moreover, the standard electrochemical measurements indicated that the functionalized ZE21B alloy had better anti-corrosion ability. In a conclusion, the dual-functional coating displays a great potential in the field of biodegradable magnesium-based implantable cardiovascular stents.