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Sample records for asymmetric vascular stent

  1. Vascular Response to Experimental Stent Malapposition and Under-Expansion.

    Science.gov (United States)

    O'Brien, Caroline C; Lopes, Augusto C; Kolandaivelu, Kumaran; Kunio, Mie; Brown, Jonathan; Kolachalama, Vijaya B; Conway, Claire; Bailey, Lynn; Markham, Peter; Costa, Marco; Ware, James; Edelman, Elazer R

    2016-07-01

    Up to 80% of all endovascular stents have malapposed struts, and while some impose catastrophic events others are inconsequential. Thirteen stents were implanted in coronary arteries of seven healthy Yorkshire pigs, using specially-designed cuffed balloons inducing controlled stent malapposition and under-expansion. Optical coherence tomography (OCT) imaging confirmed that 25% of struts were malapposed (strut-wall distance 51 ± 0.05 mm vs. apposed group 0.09 ± 0.05 mm, p = 2e-3). Imaging at follow-up revealed malapposition acutely resolved (areas (slope = 0.86, p area and lumen area (R (2) = 0.96) suggesting all lumen loss was related to contraction of elastic lamina with negligible plaque/intimal hyperplasia growth. Simulation showed this vascular recoil could be partially explained by the non-uniform strain environment created from sub-optimal expansion of device and balloon, and the inability of stent support in the malapposed region to resist recoil. Malapposition as a result of stent under-expansion is resolved acutely in healthy normal arteries, suggesting existing animal models are limited in replicating clinically observed persistent stent malapposition. PMID:26732391

  2. Vascular Response to Experimental Stent Malapposition and Under-Expansion.

    Science.gov (United States)

    O'Brien, Caroline C; Lopes, Augusto C; Kolandaivelu, Kumaran; Kunio, Mie; Brown, Jonathan; Kolachalama, Vijaya B; Conway, Claire; Bailey, Lynn; Markham, Peter; Costa, Marco; Ware, James; Edelman, Elazer R

    2016-07-01

    Up to 80% of all endovascular stents have malapposed struts, and while some impose catastrophic events others are inconsequential. Thirteen stents were implanted in coronary arteries of seven healthy Yorkshire pigs, using specially-designed cuffed balloons inducing controlled stent malapposition and under-expansion. Optical coherence tomography (OCT) imaging confirmed that 25% of struts were malapposed (strut-wall distance strut thickness) to variable extent (max. strut-wall distance malapposed group 0.51 ± 0.05 mm vs. apposed group 0.09 ± 0.05 mm, p = 2e-3). Imaging at follow-up revealed malapposition acutely resolved (struts remained malapposed at day 5), with strong correlation between lumen and the stent cross-sectional areas (slope = 0.86, p < 0.0001, R (2) = 0.94). OCT in three of the most significantly malapposed vessels at baseline showed high correlation of elastic lamina area and lumen area (R (2) = 0.96) suggesting all lumen loss was related to contraction of elastic lamina with negligible plaque/intimal hyperplasia growth. Simulation showed this vascular recoil could be partially explained by the non-uniform strain environment created from sub-optimal expansion of device and balloon, and the inability of stent support in the malapposed region to resist recoil. Malapposition as a result of stent under-expansion is resolved acutely in healthy normal arteries, suggesting existing animal models are limited in replicating clinically observed persistent stent malapposition.

  3. 4D phase contrast flow imaging for in-stent flow visualization and assessment of stent patency in peripheral vascular stents – A phantom study

    International Nuclear Information System (INIS)

    Purpose: 4D phase contrast flow imaging is increasingly used to study the hemodynamics in various vascular territories and pathologies. The aim of this study was to assess the feasibility and validity of MRI based 4D phase contrast flow imaging for the evaluation of in-stent blood flow in 17 commonly used peripheral stents. Materials and methods: 17 different peripheral stents were implanted into a MR compatible flow phantom. In-stent visibility, maximal velocity and flow visualization were assessed and estimates of in-stent patency obtained from 4D phase contrast flow data sets were compared to a conventional 3D contrast-enhanced magnetic resonance angiography (CE-MRA) as well as 2D PC flow measurements. Results: In all but 3 of the tested stents time-resolved 3D particle traces could be visualized inside the stent lumen. Quality of 4D flow visualization and CE-MRA images depended on stent type and stent orientation relative to the magnetic field. Compared to the visible lumen area determined by 3D CE-MRA, estimates of lumen patency derived from 4D flow measurements were significantly higher and less dependent on stent type. A higher number of stents could be assessed for in-stent patency by 4D phase contrast flow imaging (n = 14) than by 2D phase contrast flow imaging (n = 10). Conclusions: 4D phase contrast flow imaging in peripheral vascular stents is feasible and appears advantageous over conventional 3D contrast-enhanced MR angiography and 2D phase contrast flow imaging. It allows for in-stent flow visualization and flow quantification with varying quality depending on stent type

  4. Fabrication and In Vitro Deployment of a Laser-Activated Shape Memory Polymer Vascular Stent

    Energy Technology Data Exchange (ETDEWEB)

    Baer, G M; Small IV, W; Wilson, T S; Benett, W J; Matthews, D L; Hartman, J; Maitland, D J

    2007-04-25

    Vascular stents are small tubular scaffolds used in the treatment of arterial stenosis (narrowing of the vessel). Most vascular stents are metallic and are deployed either by balloon expansion or by self-expansion. A shape memory polymer (SMP) stent may enhance flexibility, compliance, and drug elution compared to its current metallic counterparts. The purpose of this study was to describe the fabrication of a laser-activated SMP stent and demonstrate photothermal expansion of the stent in an in vitro artery model. A novel SMP stent was fabricated from thermoplastic polyurethane. A solid SMP tube formed by dip coating a stainless steel pin was laser-etched to create the mesh pattern of the finished stent. The stent was crimped over a fiber-optic cylindrical light diffuser coupled to an infrared diode laser. Photothermal actuation of the stent was performed in a water-filled mock artery. At a physiological flow rate, the stent did not fully expand at the maximum laser power (8.6 W) due to convective cooling. However, under zero flow, simulating the technique of endovascular flow occlusion, complete laser actuation was achieved in the mock artery at a laser power of {approx}8 W. We have shown the design and fabrication of an SMP stent and a means of light delivery for photothermal actuation. Though further studies are required to optimize the device and assess thermal tissue damage, photothermal actuation of the SMP stent was demonstrated.

  5. Fabrication and in vitro deployment of a laser-activated shape memory polymer vascular stent

    Directory of Open Access Journals (Sweden)

    Matthews Dennis L

    2007-11-01

    Full Text Available Abstract Background Vascular stents are small tubular scaffolds used in the treatment of arterial stenosis (narrowing of the vessel. Most vascular stents are metallic and are deployed either by balloon expansion or by self-expansion. A shape memory polymer (SMP stent may enhance flexibility, compliance, and drug elution compared to its current metallic counterparts. The purpose of this study was to describe the fabrication of a laser-activated SMP stent and demonstrate photothermal expansion of the stent in an in vitro artery model. Methods A novel SMP stent was fabricated from thermoplastic polyurethane. A solid SMP tube formed by dip coating a stainless steel pin was laser-etched to create the mesh pattern of the finished stent. The stent was crimped over a fiber-optic cylindrical light diffuser coupled to an infrared diode laser. Photothermal actuation of the stent was performed in a water-filled mock artery. Results At a physiological flow rate, the stent did not fully expand at the maximum laser power (8.6 W due to convective cooling. However, under zero flow, simulating the technique of endovascular flow occlusion, complete laser actuation was achieved in the mock artery at a laser power of ~8 W. Conclusion We have shown the design and fabrication of an SMP stent and a means of light delivery for photothermal actuation. Though further studies are required to optimize the device and assess thermal tissue damage, photothermal actuation of the SMP stent was demonstrated.

  6. Management of Vascular Risk Factors in the Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST)

    OpenAIRE

    Meschia, James F; Voeks, Jenifer H.; Leimgruber, Pierre P.; Mantese, Vito A.; Timaran, Carlos H; Chiu, David; Bart M. Demaerschalk; Howard, Virginia J; Hughes, Susan E.; Longbottom, Mary; Howard, Annie Green; Brott, Thomas G

    2014-01-01

    Background The Carotid Revascularization Endarterectomy Versus Stenting Trial (CREST) is a multicenter randomized trial of stenting versus endarterectomy in patients with symptomatic and asymptomatic carotid disease. This study assesses management of vascular risk factors. Methods and Results Management was provided by the patient's physician, with biannual monitoring results collected by the local site. Therapeutic targets were low‐density lipoprotein, cholesterol

  7. Rapid prediction method for nonlinear expansion process of medical vascular stent

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A neural network model with high nonlinear recognition capability was constructed to describe the relationship between the deformation impact factors and the deformation results of vascular stent.Then,using the weighted correction method with the attached momentum term,the network training algorithm was optimized by introducing learning factor η and momentum factor ψ,so the speed of the network training and the system robustness were enhanced.The network was trained by some practi-cal cases,and the statistical hypothesis validation was made for the predictive errors.It was shown that the average difference between the intelligent predictive result of vascular stent deformation neu-ral network and the nonlinear finite element analysis result was less than 0.03%,and the trained net-work could perfectly predict the vascular stent deformation.Further more,the rapid evaluation tool for the vascular stent mechanics performance was established using the Pro/Toolkit and the intelligent neural network predictive model of vascular stent expansion.The proposed tool system with strong practicality and high efficiency can significantly shorten the product development cycle of vascular stent.

  8. Influence of 103Pd radioactive stent on apoptosis of vascular smooth muscle cells

    International Nuclear Information System (INIS)

    Objective: To evaluate the influence of 103Pd radioactive stent on apoptosis and its relative genes bcl-2 and bax in injured vascular media smooth muscle cells of rabbit abdominal arteries and to investigate the mechanism of 103Pd radioactive stent for preventing restenosis after angioplasty. Methods: Fifty male New Zealand rabbits were randomized into stent group and 103Pd stent group. Each group was subdivided into 5 sub-groups. Control group was set up. The study arteries were harvested at 3, 7, 14, 28 and 56 d after stenting and the pathomorphology, apoptosis analysis and in situ hybridization were performed to evaluate the expression of bcl-2 and bax mRNA. Results: The severity of the restenosis in 103Pd stent group was less than that of stent group. It was most obvious at the 56th day (P103Pd stent group had much more apoptosis of vascular smooth muscle cells than stent group did and reached the peak at the 7th day, (14.72±0.53)% vs (12.42±1.13)% (P103Pd stent group was much lower than that of stent group at 3 to 28 d. The difference was most obvious at the 28th day after stenting, (18.43± 0.67)% vs (21.55±0.93)% (P103Pd stent group was higher than that of stent group, the peak was at the 7th day, (11.17±0.94)% vs (9.30±1.01)%. The ratio of bcl-2/bax in 103Pd stent group was much lower than that of stent group at 3 to 28 d. Linear correlation analysis showed that there was significant negative correlation between bcl-2 mRNA and apoptosis. Between bax mRNA and apoptosis, the positive correlation was found (P103Pd radioactive stent induced more significant apoptosis in vascular media smooth muscle cells by promoting the expression of apoptosis related genes and relieved the expanding of restenosis

  9. Dose rate calculations from radioactive vascular stents: DPK versus exact MC approach

    International Nuclear Information System (INIS)

    Vascular stents activated with radioactive isotopes are planned to be used in clinical practice to prevent restenosis in human coronary arteries after balloon angioplasty. Medical stents are cylindrical meshes and their complex geometry is usually treated for energy dose calculation with approximate dose point kernel (DPK) approach. The important point missed in the DPK approach is the absence of the stent material and, hence, the absence of energy absorption inside the stent. We have performed a comparison between DPK and exact Monte Carlo calculations for some simplified stent models. It appears that DPK approximation significantly overestimates pike dose values especially for the case of γ-emitting sources. We suggest DPK kernel normalization, which minimizes the difference at relatively far distances, while significant discrepancies near the stent surface still remain. (orig.)

  10. Enhanced endothelial cell functions on rosette nanotube-coated titanium vascular stents

    Directory of Open Access Journals (Sweden)

    Eli Fine

    2009-04-01

    Full Text Available Eli Fine1, Lijie Zhang1, Hicham Fenniri2, Thomas J Webster1 1Department of Engineering, Brown University, Providence, RI, USA; 2National Institute for Nanotechnology and Department of Chemistry, University of Alberta, Edmonton, AB, CanadaAbstract: One of the main problems with current vascular stents is a lack of endothelial cell interactions, which if sufficient, would create a uniform healthy endothelium masking the underlying foreign metal from inflammatory cell interference. Moreover, if endothelial cells from the arterial wall do not adhere to the stent, the stent can become loose and dislodge. Therefore, the objective of this in vitro study was to design a novel biomimetic nanostructured coating (that does not contain drugs on conventional vascular stent materials (specifically, titanium for improving vascular stent applications. Rosette nanotubes (RNTs are a new class of biomimetic nanotubes that self-assemble from DNA base analogs and have been shown in previous studies to sufficiently coat titanium and enhance osteoblast cell functions. RNTs have many desirable properties for use as vascular stent coatings including spontaneous self-assembly in body fluids, tailorable surface chemistry for specific implant applications, and nanoscale dimensions similar to those of the natural vascular extracellular matrix. Importantly, the results of this study provided the first evidence that RNTs functionalized with lysine (RNT–K, even at low concentrations, significantly increase endothelial cell density over uncoated titanium. Specifically, 0.01 mg/mL RNT–K coated titanium increased endothelial cell density by 37% and 52% compared to uncoated titanium after 4 h and three days, respectively. The excellent cytocompatibility properties of RNTs (as demonstrated here for the first time for endothelial cells suggest the need for the further exploration of these novel nanostructured materials for vascular stent applications.Keywords: stents

  11. Platelet Activation and Inhibition in Connection with Vascular Stents

    OpenAIRE

    Christensen, Kjeld

    2007-01-01

    This thesis describes the Chandler loop, which makes it possible to conduct studies in vitro of molecular and cellular interactions between whole blood and stents. It was possible to monitor activation and inhibition of the cascades systems, leukocytes and platelets by combining different platelet inhibitors and heparin coating of stents. The clinical study was performed on patients with ACS undergoing PCI and stent implantation. In this study platelet activation markers P-selectin, and αIIb/...

  12. Effects of antibacterial nanostructured composite films on vascular stents: hemodynamic behaviors, microstructural characteristics, and biomechanical properties.

    Science.gov (United States)

    Cheng, Han-Yi; Hsiao, Wen-Tien; Lin, Li-Hsiang; Hsu, Ya-Ju; Sinrang, Andi Wardihan; Ou, Keng-Liang

    2015-01-01

    The purpose of this research was to investigate stresses resulting from different thicknesses and compositions of hydrogenated Cu-incorporated diamond-like carbon (a-C:H/Cu) films at the interface between vascular stent and the artery using three-dimensional reversed finite element models (FEMs). Blood flow velocity variation in vessels with plaques was examined by angiography, and the a-C:H/Cu films were characterized by transmission electron microscopy to analyze surface morphology. FEMs were constructed using a computer-aided reverse design system, and the effects of antibacterial nanostructured composite films in the stress field were investigated. The maximum stress in the vascular stent occurred at the intersections of net-like structures. Data analysis indicated that the stress decreased by 15% in vascular stents with antibacterial nanostructured composite films compared to the control group, and the stress decreased with increasing film thickness. The present results confirmed that antibacterial nanostructured composite films improve the biomechanical properties of vascular stents and release abnormal stress to prevent restenosis. The results of the present study offer the clinical benefit of inducing superior biomechanical behavior in vascular stents.

  13. Simultaneous occlusion of left anterior descending and left circumflex arteries by very late stent thrombosis: vascular response to drug-eluting stents assessed by intravascular ultrasound.

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    Yamawaki, Masahiro; Onuma, Yoshinobu; Nakano, Masatsugu; Muramatsu, Takashi; Nakatani, Shimpei; Ishibashi, Yuki; Ishimori, Hiroshi; Hirano, Keisuke; Ito, Yoshiaki; Tsukahara, Reiko; Muramatsu, Toshiya

    2015-11-01

    Very late stent thrombosis (VLST) is a catastrophic complication after implantation of a drug-eluting stent (DES). It has been reported that VLST is associated with pathological changes, which often include late acquired incomplete stent apposition (LAISA) with thrombus formation. In addition, the vascular response to the stent (evaginations, neointimal growth, and thrombosis) and the incidence of LAISA are reported to vary among the different types of DES. We experienced a patient with cardiogenic shock induced by simultaneous VLST of both the left anterior descending artery (LAD) and the left circumflex artery (LCX) at 3 years after implantation of two sirolimus-eluting stents. Intravascular ultrasound (IVUS) showed LAISA of both arteries. A paclitaxel-eluting stent, which had been implanted in the right coronary artery 3 years earlier, did not show such a finding. IVUS revealed "different vascular reactions" to "different types of DES" in this patient.

  14. Fiber laser micromachining of thin NiTi tubes for shape memory vascular stents

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    Liu, Lei; Li, Dong Bo; Tong, Yi Fei; Zhu, Yu Fu

    2016-07-01

    Nickel titanium (NiTi) alloy has widely been used in the vascular stent manufacturing due to its excellent properties. Neodymium-doped yttrium aluminum garnet (Nd:YAG) laser is commonly used for the preparation of metal vascular stents. Recently, fiber lasers have been used for stent profiling for better cutting quality. To investigate the cutting-kerf characters of NiTi vascular stents fabricated by fiber laser cutting, laser cutting experiments with thin NiTi tubes were conducted in this study, while NiTi sheets were used in other fiber laser cutting studies. Different with striation topography, new topographies such as layer topography and topography mixed with layers and striations were observed, and the underlying reason for new topographies was also discussed. Comparative research on different topographies was conducted through analyzing the surface roughness, kerf width, heat-affected zone (HAZ) and dross formation. Laser cutting process parameters have a comprehensive influence on the cutting quality; in this study, the process parameters' influences on the cutting quality were studied from the view of power density along the cutting direction. The present research provides a guideline for improving the cutting quality of NiTi vascular stents.

  15. Preparation and Characterization of New Nano-Composite Scaffolds Loaded With Vascular Stents

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    Tianbin Ren

    2012-03-01

    Full Text Available In this study, vascular stents were fabricated from poly (lactide-ε-caprolactone/collagen/nano-hydroxyapatite (PLCL/Col/nHA by electrospinning, and the surface morphology and breaking strength were observed or measured through scanning electron microscopy and tensile tests. The anti-clotting properties of stents were evaluated for anticoagulation surfaces modified by the electrostatic layer-by-layer self-assembly technique. In addition, nano-composite scaffolds of poly (lactic-co-glycolic acid/polycapr-olactone/nano-hydroxyapatite (PLGA/PCL/nHA loaded with the vascular stents were prepared by thermoforming-particle leaching and their basic performance and osteogenesis were tested in vitro and in vivo. The results show that the PLCL/Col/nHA stents and PLGA/PCL/nHA nano-composite scaffolds had good surface structures, mechanical properties, biocompatibility and could guide bone regeneration. These may provide a new way to build vascularized-tissue engineered bone to repair large bone defects in bone tissue engineering.

  16. Evaluation of an asymmetric stent patch design for a patient specific intracranial aneurysm using computational fluid dynamic (CFD) calculations in the computed tomography (CT) derived lumen

    Science.gov (United States)

    Kim, Minsuok; Ionita, Ciprian; Tranquebar, Rekha; Hoffmann, Kenneth R.; Taulbee, Dale B.; Meng, Hui; Rudin, Stephen

    2006-03-01

    Stenting may provide a new, less invasive therapeutic option for cerebral aneurysms. However, a conventional porous stent may be insufficient in modifying the blood flow for clinical aneurysms. We designed an asymmetric stent consisting of a low porosity patch welded onto a porous stent for an anterior cerebral artery aneurysm of a specific patient geometry to block the strong inflow jet. To evaluate the effect of the patch on aneurysmal flow dynamics, we "virtually" implanted it into the patient's aneurysm geometry and performed Computational Fluid Dynamics (CFD) analysis. The patch was computationally deformed to fit into the vessel lumen segmented from the patient CT reconstructions. After the flow calculations, a patch with the same design was fabricated using laser cutting techniques and welded onto a commercial porous stent, creating a patient-specific asymmetric stent. This stent was implanted into a phantom, which was imaged with X-ray angiography. The hemodynamics of untreated and stented aneurysms were compared both computationally and experimentally. It was found from CFD of the patient aneurysm that the asymmetric stent effectively blocked the strong inflow jet into the aneurysm and eliminated the flow impingement on the aneurysm wall at the dome. The impact zone with elevated wall shear stress was eliminated, the aneurysmal flow activity was substantially reduced, and the flow was considerably reduced. Experimental observations corresponded well qualitatively with the CFD results. The demonstrated asymmetric stent could lead to a new minimally invasive image guided intervention to reduce aneurysm growth and rupture.

  17. Experimental Study of 103Pd Stent Affecting Dynamic Equilibrium Between Proliferation and Apoptosis of Vascular Smooth Muscle Cells

    Institute of Scientific and Technical Information of China (English)

    Liu Yingmei; Fu Yuewu; Wei Yulin; Wu Wei

    2006-01-01

    Objectives By observing γ radioactive 103Pd stent affecting the proliferation and apoptosis of vascular smooth muscle cells (VSMCs) to explore the mechanism of radioactive stent preventing in-stent restenosis. Methods Fifty male New Zealand rabbits were randomized into stent group and 103Pd stent group. Control group was set up. The materials were harvested on 3, 7, 14, 28, 56 days after operation and the following investigations were carried out, including pathomorphology, immunohistochemistry, apoptosis (TUNEL) and in situs hybridization studies. Results ①The severity of the stenosis in 103Pd stent group was less than that of stent group.It was the most obvious on 56th day (P < 0.01).②The expression of PCNA of 103Pd stent group was lower than that of stent group on 3 to 28 days. It was the most obvious on 7th day, 16.35%±0.79% vs 24.36%±0.55% (P< 0.01 ). ③TUNEL method showed that the 103Pd stent group had much more apoptosis of VSMCs than that of stent group. The highest rate of apoptosis appeared on day 7, 14.72%±0.53% vs 12.42%±1.13% (P<0.01). ④ By calculating the ratio of PCNA/apoptosis (P:A), a much lower ratio was seen in 103Pd-stent group than that of stent group at 3 to 28 days. There was significant statistic difference between two groups (P<0.05). ⑤For bcl-2/bax ratio, the result in 103Pd-stent group was lower than that of stent group at 3 to 28 days. It had significant statistic difference (P < 0.05). Conclusions γ radioactive stent can inhibit the proliferation and accelerate apoptosis of injured media VSMCs. Also it can decrease the ratio of proliferation to apoptosis and relieve the severity of restenosis.

  18. Experimental study of vascular intimal hyperplasia with the influence of polymer-coated dexamethasone (DXM)-releasing stent

    International Nuclear Information System (INIS)

    Objective: Polymer-coated, dexamethasone (DXM)-releasing stents were tested in order to assess the efficacy of DXM released locally for the prevention of vascular restenosis due to intimal hyperplasia. Methods: Strecker stents coated with a biodegradable membrane containing DXM were implanted percutaneously into the femoral artery in 14 dogs. The contralateral artery received a conventional non-coated stent serving as control. The drugs were eluted by degradation of the carrier membrane. Follow-up intraarterial digital subtraction angiography (DSA) was obtained at 3, 6, 9, 12 and 24 weeks with subsequent autopsies. Specimens for gross and microscopic pathology were obtained together with histo-morphometry performed. Results: Four of 14 DXM-coated stents showed thrombotic occlusion within the first 3 weeks while ten DXM-coated stents remained patent. Follow-up DSA of DXM-coated stents showed a significantly wider lumen than the non-coated stents. Morphometry revealed less intimal hyperplasia over DXM-coated stents than over non-coated stents (P < 0.05). Conclusions: DXM-coated stents reduce neo-intimal hyperplasia in dogs when compared with non-coated stents

  19. Protected stent retriever thrombectomy prevents iatrogenic emboli in new vascular territories

    Energy Technology Data Exchange (ETDEWEB)

    Klinger-Gratz, Pascal P. [Bern University Hospital and University of Bern, Department of Diagnostic and Interventional Neuroradiology, Inselspital, Freiburgstrasse 10, Bern (Switzerland); University of Basel, Department of Radiology, Basel (Switzerland); Schroth, Gerhard; Gralla, Jan; Weisstanner, Christian; Verma, Rajeev K.; Mordasini, Pasquale; Kellner-Weldon, Frauke; Hsieh, Kety; El-Koussy, Marwan [Bern University Hospital and University of Bern, Department of Diagnostic and Interventional Neuroradiology, Inselspital, Freiburgstrasse 10, Bern (Switzerland); Jung, Simon [Bern University Hospital and University of Bern, Department of Diagnostic and Interventional Neuroradiology, Inselspital, Freiburgstrasse 10, Bern (Switzerland); Bern University Hospital and University of Bern, Department of Neurology, Inselspital, Bern (Switzerland); Heldner, Mirjam R.; Fischer, Urs; Arnold, Marcel; Mattle, Heinrich P. [Bern University Hospital and University of Bern, Department of Neurology, Inselspital, Bern (Switzerland)

    2015-10-15

    Diagnostic tools to show emboli reliably and protection techniques against embolization when employing stent retrievers are necessary to improve endovascular stroke therapy. The aim of the present study was to investigate iatrogenic emboli using susceptibility-weighted imaging (SWI) in an open series of patients who had been treated with stent retriever thrombectomy using emboli protection techniques. Patients with anterior circulation stroke examined with MRI before and after stent retriever thrombectomy were assessed for iatrogenic embolic events. Thrombectomy was performed in flow arrest and under aspiration using a balloon-mounted guiding catheter, a distal access catheter, or both. In 13 of 57 patients (22.8 %) post-interventional SWI sequences detected 16 microemboli. Three of them were associated with small ischemic lesions on diffusion-weighted imaging (DWI). None of the microemboli were located in a new vascular territory, none showed clinical signs, and all 13 patients have been rated as Thrombolysis in Cerebral Infarction (TICI) 2b (n = 3) or 3 (n = 10). Retrospective reevaluation of the digital subtraction angiography (DSA) detected discrete flow stagnation nearby the iatrogenic microemboli in four patients with a positive persistent collateral sign in one. Our study demonstrates two things: First, SWI seems to be more sensitive to detect emboli than DWI and DSA and, second, proximal or distal protected stent retriever thrombectomy seems to prevent iatrogenic embolization into new vascular territories during retraction of the thrombus, but not downstream during mobilization of the thrombus. Both techniques should be investigated and refined further. (orig.)

  20. Interleukin-6 and asymmetric dimethylarginine are associated with platelet activation after percutaneous angioplasty with stent implantation.

    Science.gov (United States)

    Gremmel, Thomas; Perkmann, Thomas; Kopp, Christoph W; Seidinger, Daniela; Eichelberger, Beate; Koppensteiner, Renate; Steiner, Sabine; Panzer, Simon

    2015-01-01

    Data linking in vivo platelet activation with inflammation and cardiovascular risk factors are scarce. Moreover, the interrelation between endothelial dysfunction as early marker of atherosclerosis and platelet activation has not been studied, so far. We therefore sought to investigate the associations of inflammation, endothelial dysfunction and cardiovascular risk factors with platelet activation and monocyte-platelet aggregate (MPA) formation in 330 patients undergoing angioplasty with stent implantation for atherosclerotic cardiovascular disease. P-selectin expression, activation of glycoprotein IIb/IIIa and MPA formation were determined by flow cytometry. Interleukin (IL)-6, high sensitivity C-reactive protein and asymmetric dimethylarginine (ADMA) were measured by commercially available assays. IL-6 was the only parameter which was independently associated with platelet P-selectin expression and activated GPIIb/IIIa as well as with leukocyte-platelet interaction in multivariate regression analysis (all p<0.05). ADMA was independently associated with GPIIb/IIIa activation (p<0.05). Patients with high IL-6 exhibited a significantly higher expression of P-selectin than patients with low IL-6 (p=0.001), whereas patients with high ADMA levels showed a more pronounced activation of GPIIb/IIIa than patients with low ADMA (p=0.003). In conclusion, IL-6 and ADMA are associated with platelet activation after percutaneous angioplasty with stent implantation. It remains to be established whether they act prothrombotic and atherogenic themselves or are just surrogate markers for atherosclerosis with concomitant platelet activation.

  1. Interleukin-6 and asymmetric dimethylarginine are associated with platelet activation after percutaneous angioplasty with stent implantation.

    Directory of Open Access Journals (Sweden)

    Thomas Gremmel

    Full Text Available Data linking in vivo platelet activation with inflammation and cardiovascular risk factors are scarce. Moreover, the interrelation between endothelial dysfunction as early marker of atherosclerosis and platelet activation has not been studied, so far. We therefore sought to investigate the associations of inflammation, endothelial dysfunction and cardiovascular risk factors with platelet activation and monocyte-platelet aggregate (MPA formation in 330 patients undergoing angioplasty with stent implantation for atherosclerotic cardiovascular disease. P-selectin expression, activation of glycoprotein IIb/IIIa and MPA formation were determined by flow cytometry. Interleukin (IL-6, high sensitivity C-reactive protein and asymmetric dimethylarginine (ADMA were measured by commercially available assays. IL-6 was the only parameter which was independently associated with platelet P-selectin expression and activated GPIIb/IIIa as well as with leukocyte-platelet interaction in multivariate regression analysis (all p<0.05. ADMA was independently associated with GPIIb/IIIa activation (p<0.05. Patients with high IL-6 exhibited a significantly higher expression of P-selectin than patients with low IL-6 (p=0.001, whereas patients with high ADMA levels showed a more pronounced activation of GPIIb/IIIa than patients with low ADMA (p=0.003. In conclusion, IL-6 and ADMA are associated with platelet activation after percutaneous angioplasty with stent implantation. It remains to be established whether they act prothrombotic and atherogenic themselves or are just surrogate markers for atherosclerosis with concomitant platelet activation.

  2. Improving hemocompatibility and accelerating endothelialization of vascular stents by a copper-titanium film.

    Science.gov (United States)

    Liu, Hengquan; Pan, Changjiang; Zhou, Shijie; Li, Junfeng; Huang, Nan; Dong, Lihua

    2016-12-01

    Bio-inorganic films and drug-eluting coatings are usually used to improve the hemocompatibility and inhibit restenosis of vascular stent; however, above bio-performances couldn't combine together with single materials. In the present study, we reported a simple approach to fabricate a metal film with the aim of imparting the stent with good blood compatibility and accelerating endothelialization. The films with various ratios of Cu and Ti were prepared through the physical vapor deposition. Phase structure and element composition were investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The releasing volume of copper ion in Cu/Ti film was determined by immersing test. The hemolysis ratio, platelet adhesion and clotting time were applied to evaluate the hemocompatibility. The proliferative behaviors of endothelial cells and smooth muscle cells under certain copper concentration were investigated in vitro and in vivo. Results indicated that copper-titanium films exhibited good hemocompatibility in vitro; however, the increase of Cu/Ti ratio could lead to increasing hemolysis ratio. Endothelial cells displayed more proliferative than smooth muscle cells when the copper concentration was film with low copper in vivo was observed at the 2nd week, indicating that the copper-titanium film with the lower copper concentration could promote endothelialization. Therefore, the inorganic copper-titanium film could be potential biomaterials to improve blood compatibility and accelerating endothelialization of vascular stents.

  3. Improving hemocompatibility and accelerating endothelialization of vascular stents by a copper-titanium film.

    Science.gov (United States)

    Liu, Hengquan; Pan, Changjiang; Zhou, Shijie; Li, Junfeng; Huang, Nan; Dong, Lihua

    2016-12-01

    Bio-inorganic films and drug-eluting coatings are usually used to improve the hemocompatibility and inhibit restenosis of vascular stent; however, above bio-performances couldn't combine together with single materials. In the present study, we reported a simple approach to fabricate a metal film with the aim of imparting the stent with good blood compatibility and accelerating endothelialization. The films with various ratios of Cu and Ti were prepared through the physical vapor deposition. Phase structure and element composition were investigated by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The releasing volume of copper ion in Cu/Ti film was determined by immersing test. The hemolysis ratio, platelet adhesion and clotting time were applied to evaluate the hemocompatibility. The proliferative behaviors of endothelial cells and smooth muscle cells under certain copper concentration were investigated in vitro and in vivo. Results indicated that copper-titanium films exhibited good hemocompatibility in vitro; however, the increase of Cu/Ti ratio could lead to increasing hemolysis ratio. Endothelial cells displayed more proliferative than smooth muscle cells when the copper concentration was <7.5μg/ml, however both cells tended to apoptosis to some degree when the copper concentration was increased. The complete endothelialization of the film with low copper in vivo was observed at the 2nd week, indicating that the copper-titanium film with the lower copper concentration could promote endothelialization. Therefore, the inorganic copper-titanium film could be potential biomaterials to improve blood compatibility and accelerating endothelialization of vascular stents. PMID:27612815

  4. Nanophasic biodegradation enhances the durability and biocompatibility of magnesium alloys for the next-generation vascular stents

    Science.gov (United States)

    Mao, Lin; Shen, Li; Niu, Jialin; Zhang, Jian; Ding, Wenjiang; Wu, Yu; Fan, Rong; Yuan, Guangyin

    2013-09-01

    Biodegradable metal alloys emerge as a new class of biomaterials for tissue engineering and medical devices such as cardiovascular stents. Deploying biodegradable materials to fabricate stents not only obviates a second surgical intervention for implant removal but also circumvents the long-term foreign body effect of permanent implants. However, these materials for stents suffer from an un-controlled degradation rate, acute toxic responses, and rapid structural failure presumably due to a non-uniform, fast corrosion process. Here we report that highly uniform, nanophasic degradation is achieved in a new Mg alloy with unique interstitial alloying composition as the nominal formula Mg-2.5Nd-0.2Zn-0.4Zr (wt%, hereafter, denoted as JDBM). This material exhibits highly homogeneous nanophasic biodegradation patterns as compared to other biodegradable metal alloy materials. Consequently it has significantly reduced degradation rate determined by electrochemical characterization. The in vitro cytotoxicity test using human vascular endothelial cells indicates excellent biocompatibility and potentially minimal toxic effect on arterial vessel walls. Finally, we fabricated a cardiovascular stent using JDBM and performed in vivo long-term assessment via implantation of this stent in an animal model. The results confirmed the reduced degradation rate in vivo, excellent tissue compatibility and long-term structural and mechanical durability. Thus, this new Mg-alloy with highly uniform nanophasic biodegradation represents a major breakthrough in the field and a promising material for manufacturing the next generation biodegradable vascular stents.

  5. The influence of vascular anatomy on carotid artery stenting: a parametric study for damage assessment.

    Science.gov (United States)

    Iannaccone, F; Debusschere, N; De Bock, S; De Beule, M; Van Loo, D; Vermassen, F; Segers, P; Verhegghe, B

    2014-03-01

    Carotid artery stenting is emerging as an alternative technique to surgery for the treatment of symptomatic severe carotid stenosis. Clinical and experimental evidence demonstrates that both plaque morphology and biomechanical changes due to the device implantation can be possible causes of an unsuccessful treatment. In order to gain further insights of the endovascular intervention, a virtual environment based on structural finite element simulations was built to emulate the stenting procedure on generalized atherosclerotic carotid geometries which included a damage model to quantify the injury of the vessel. Five possible lesion scenarios were simulated by changing both material properties and vascular geometrical features to cover both presumed vulnerable and stable plaques. The results were analyzed with respect to lumen gain and wall stresses which are potentially related to the failure of the procedure according to previous studies. Our findings show that an elliptic lumen shape and a thinner fibrous cap with an underlying lipid pool result in higher stenosis reduction, while large calcifications and fibrotic tissue are more prone to recoil. The shielding effect of a thicker fibrous cap helps to reduce local compressive stresses in the soft plaque. The presence of a soft plaque reduces the damage in the healthy vascular structures. Contrarily, the presence of hard plaque promotes less damage volume in the fibrous cap and reduces stress peaks in this region, but they seem to increase stresses in the media-intima layer. Finally the reliability of the achieved results was put into clinical perspective.

  6. Vascular brachytherapy revisited for in-stent restenosis in the drug-eluting stent era: current status and future perspective

    Institute of Scientific and Technical Information of China (English)

    LI Xiong-jie; Seung-Woon Rha; Sunil-P Wani; WANG Lin; Kanhaiya-L Poddar; Dong-Joo Oh

    2009-01-01

    @@ Percutaneous coronary intervention (PCI) with drug-eluting stents (DESs) has revolutionized the management of atherosclerotic coronary artery disease. However, in-stent restenosis (ISR) has been the downside of all coronary interventions with the devices that have been tested so far, even in the DES era.

  7. New treatment of iliac artery disease: focus on the Absolute Pro® Vascular Self-Expanding Stent System

    Directory of Open Access Journals (Sweden)

    Gates L

    2013-09-01

    Full Text Available Lindsay Gates, Jeffrey Indes Vascular and Endovascular Surgery, Yale University School of Medicine, New Haven, CT, USA Abstract: Management of iliac artery disease has evolved over the years, from a surgical-only approach to a primarily endovascular-only approach as the first line treatment option. This has been continuously improved upon with the advent of new devices and applied technologies. Most recently in particular, the literature has shown good, reliable outcomes with the use of self-expandable stents in iliac artery atherosclerotic lesions. Nevertheless, no device is without its limitations, and the Absolute Pro® Vascular Self-Expanding Stent System was designed with the intent of overcoming some of the shortcomings of other available stents while maintaining acceptable postprocedural outcomes. Based on preliminary industry-acquired data, it has achieved these goals and appears to be an emergent competitor for the treatment of both focal and complex iliac artery lesions. Keywords: Absolute-Pro®, iliac stent, self-expanding stents, atherosclerotic disease

  8. Hydrophilic surface modification of polymer vascular prostheses and metal endoluminal stents

    Science.gov (United States)

    Amery, Drew Powell

    1997-12-01

    Large diameter vascular replacements of GORE-TEXsp°ler or Dacronsp°ler are frequently used to replace damaged arteries. Poor long term patency of small diameter grafts, 6 millimeters or less, is attributed to platelet adhesion and the inability to regenerate a blood contacting surface of vascular endothelium. Metal endoluminal stents are vascular prostheses used to keep arterial lumens open following angioplasty. Complications for these implants include short term thrombogenicity and long term restenosis. This study was directed to the synthesis and characterization of more biocompatible surfaces for these devices. Gamma radiation induced-graft polymerization and radio frequency plasma activation was investigated to surface modify polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), expanded polytetrafluoroethylene (ePTFE), and 316 stainless steel. To mimic natural biocompatible tissue surfacesl a series of hydrophilic polymers were grafted onto PMMA, PET, and ePTFE. Hydrophilic graft polymers were derived from N-vinyl pyrrolidone (NVP), potassium sulfopropylacrylate (KSPA), and dimethylacrylamide, and were grafted copolymerized with several bioactive compounds in a two step modification process. Complex graft surfaces containing fibronectin (Fn), laminin (Lm), type IV collagen (IV), heparin sulfate (Hp), albumin (Alb), and a synthetic fibronectin like protein polymer (RGD) were prepared. For surface modification of endoluminal stents of 316 stainless and tantalum, a combination of RF plasma activation combined with gamma radiation induced grafting was studied. Plasma deposition of hydrophobic poly(hexane) primer layers with water plasma oxidation were examined for initial metal surface activation. Surfaces were characterized by gravimetric analysis, contact angle goniometry, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Auger depth proGling, optical microscopy (OM), and low voltage scanning electron

  9. Percutaneous transluminal angioplasty (PTA) and venous stenting in hemodialysis patients with vascular access-related venous stenosis or occlusion

    Energy Technology Data Exchange (ETDEWEB)

    Christidou, Fotini P. [Renal Unit, G.H. ' G. Papanikolaou' , Thessaloniki (Greece); Kalpakidis, Vasilios I. [Department of Radiology, G.H. ' G. Papanikolaou' , Thessaloniki (Greece); Iatrou, Kostas D. [Department of Radiology, G.H. ' G. Papanikolaou' , Thessaloniki (Greece); Zervidis, Ioannis A. [Department of Radiology, G.H. ' G. Papanikolaou' , Thessaloniki (Greece); Bamichas, Gerasimos I. [Renal Unit, G.H. ' G. Papanikolaou' , Thessaloniki (Greece); Gionanlis, Lazaros C. [Renal Unit, G.H. ' G. Papanikolaou' , Thessaloniki (Greece); Natse, Taisir A. [Renal Unit, G.H. ' G. Papanikolaou' , Thessaloniki (Greece); Sombolos, Kostas J. [Renal Unit, G.H. ' G. Papanikolaou' , Thessaloniki (Greece)]. E-mail: sobolos@spark.net.gr

    2006-05-15

    Aim of the study: To present our experience with PTA and venous stenting in hemodialysis patients with vascular access (VA) related venous stenosis or occlusion. Patients - methods: We studied retrospectively 22 hemodialysis patients with VA-related venous stenosis or occlusions that were treated with PTA and subsequent stenting. The following lesions were detected by digital subtraction venography: occlusion of the brachiocephalic and/or subclavian veins in four patients, stenosis (80-90%) of the same veins in 10 patients, stenosis (80-95%) of the axillary vein in four patients, brachial vein stenosis in two patients, and cephalic vein stenosis in two patients. The follow-up period ranged from 3 to 29 months (mean 15.4 {+-} 9.8 months). Primary and cumulative stent patency was recorded. Results: Twenty-two primary venous PTA-stent implantation procedures were performed using 25 stents. The initial deployment of these 25 stents was technically successful, with complete opening (>80%) of the vein's lumen in all but one patient (95.4%). The patency of the vein immediately after the stenting procedure was greater than 90% in 13 patients, 80-90% in eight patients, and less than 40% in the case involving failure. Seventeen episodes of re-obstruction occurred in 13 patients (59%), and all were treated with the same PTA-stent procedures. At the end of the study period 47 stents had been placed in patients. The 3, 6, 12 and 24-month primary patency rates were 88.3%, 65.3%, 45.6% and 25.5%, respectively. Overall cumulative stent patency was 95.4% after 3 months, 79% after 6 months, 74% after 12 months, and 62.8% after 24 months. Conclusion: PTA with primary venous stenting is an effective method for the treatment of VA-related stenosis or occlusion. However, repeat and sometimes multiple interventions are usually needed for the treatment of re-stenosis or re-occlusion episodes.

  10. Lean manufacturing and Toyota Production System terminology applied to the procurement of vascular stents in interventional radiology.

    Science.gov (United States)

    de Bucourt, Maximilian; Busse, Reinhard; Güttler, Felix; Wintzer, Christian; Collettini, Federico; Kloeters, Christian; Hamm, Bernd; Teichgräber, Ulf K

    2011-08-01

    OBJECTIVES: To apply the economic terminology of lean manufacturing and the Toyota Production System to the procurement of vascular stents in interventional radiology. METHODS: The economic- and process-driven terminology of lean manufacturing and the Toyota Production System is first presented, including information and product flow as well as value stream mapping (VSM), and then applied to an interdisciplinary setting of physicians, nurses and technicians from different medical departments to identify wastes in the process of endovascular stent procurement in interventional radiology. RESULTS: Using the so-called seven wastes approach of the Toyota Production System (waste of overproducing, waiting, transport, processing, inventory, motion and waste of defects and spoilage) as well as further waste characteristics (gross waste, process and method waste, and micro waste), wastes in the process of endovascular stent procurement in interventional radiology were identified and eliminated to create an overall smoother process from the procurement as well as from the medical perspective. CONCLUSION: Economic terminology of lean manufacturing and the Toyota Production System, especially VSM, can be used to visualise and better understand processes in the procurement of vascular stents in interventional radiology from an economic point of view. PMID:22347963

  11. Lean manufacturing and Toyota Production System terminology applied to the procurement of vascular stents in interventional radiology.

    Science.gov (United States)

    de Bucourt, Maximilian; Busse, Reinhard; Güttler, Felix; Wintzer, Christian; Collettini, Federico; Kloeters, Christian; Hamm, Bernd; Teichgräber, Ulf K

    2011-08-01

    OBJECTIVES: To apply the economic terminology of lean manufacturing and the Toyota Production System to the procurement of vascular stents in interventional radiology. METHODS: The economic- and process-driven terminology of lean manufacturing and the Toyota Production System is first presented, including information and product flow as well as value stream mapping (VSM), and then applied to an interdisciplinary setting of physicians, nurses and technicians from different medical departments to identify wastes in the process of endovascular stent procurement in interventional radiology. RESULTS: Using the so-called seven wastes approach of the Toyota Production System (waste of overproducing, waiting, transport, processing, inventory, motion and waste of defects and spoilage) as well as further waste characteristics (gross waste, process and method waste, and micro waste), wastes in the process of endovascular stent procurement in interventional radiology were identified and eliminated to create an overall smoother process from the procurement as well as from the medical perspective. CONCLUSION: Economic terminology of lean manufacturing and the Toyota Production System, especially VSM, can be used to visualise and better understand processes in the procurement of vascular stents in interventional radiology from an economic point of view.

  12. Distinctive effects of CD34- and CD133-specific antibody-coated stents on re-endothelialization and in-stent restenosis at the early phase of vascular injury

    OpenAIRE

    Wu, Xue; Yin, Tieying; Tian, Jie; Tang, Chaojun; Huang, Junli; Zhao, Yinping; Zhang, Xiaojuan; Deng, Xiaoyan; Fan, Yubo; Yu, Donghong; Wang, Guixue

    2015-01-01

    It is not clear what effects of CD34- and CD133-specific antibody-coated stents have on re-endothelialization and in-stent restenosis (ISR) at the early phase of vascular injury. This study aims at determining the capabilities of different coatings on stents (e.g. gelatin, anti-CD133 and anti-CD34 antibodies) to promote adhesion and proliferation of endothelial progenitor cells (EPCs). The in vitro study revealed that the adhesion force enabled the EPCs coated on glass slides to withstand flo...

  13. Investigation Of Interaction Between Nitinol Stent And A Vascular Plaque Using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Recep Güneş

    2012-06-01

    Full Text Available In this study, the interaction between the Nitinol stent and the artery with plaque was investigated using finite element method. The occurring pressure values during the cardiac contraction (systolic and loosening (diastolic were applied as loading to the modeled system with Nitinol stent. In the light of the stress values, the suitability of the Nitinol stent in an artery with plaque was investigated. In the analysis, Nitinol stent was assumed to be shape memory alloy, and artery and plaque were assumed to behave linearly elastic. As a result, the stress and deformations in the plaque and artery due to the interference of Nitinol stent were discussed and concluded that the structure of artery with plaque can be expanded in accordance with Nitinol stent.

  14. Strategy for optimal side-branch positioning of bioresorbable vascular scaffolds in dedicated 2-stent techniques: Insights from optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, Tadashi; Costopoulos, Charis; Sato, Katsumasa; Naganuma, Toru [Interventional Cardiology Unit, San Raffaele Scientific Institute, Milan (Italy); Interventional Cardiology Unit, EMO-GVM Centro Cuore Columbus, Milan (Italy); Panoulas, Vasileios F. [Interventional Cardiology Unit, San Raffaele Scientific Institute, Milan (Italy); Interventional Cardiology Unit, EMO-GVM Centro Cuore Columbus, Milan (Italy); Imperial College London, National Heart and Lung Institute, London (United Kingdom); Figini, Filippo; Latib, Azeem [Interventional Cardiology Unit, San Raffaele Scientific Institute, Milan (Italy); Interventional Cardiology Unit, EMO-GVM Centro Cuore Columbus, Milan (Italy); Colombo, Antonio, E-mail: info@emocolumbus.it [Interventional Cardiology Unit, San Raffaele Scientific Institute, Milan (Italy); Interventional Cardiology Unit, EMO-GVM Centro Cuore Columbus, Milan (Italy)

    2014-07-15

    We present a case of a left anterior descending artery/diagonal branch bifurcation successfully treated with a dedicated 2-stent technique utilizing bioresorbable vascular scaffolds, where the bifurcation angle did not strictly allow a T-stenting approach. We also propose a strategy to avoid or reduce scaffold overlap in the main branch, especially important in view of the bulkier size of these novel devices.

  15. Strategy for optimal side-branch positioning of bioresorbable vascular scaffolds in dedicated 2-stent techniques: insights from optical coherence tomography.

    Science.gov (United States)

    Miyazaki, Tadashi; Costopoulos, Charis; Sato, Katsumasa; Naganuma, Toru; Panoulas, Vasileios F; Figini, Filippo; Latib, Azeem; Colombo, Antonio

    2014-01-01

    We present a case of a left anterior descending artery/diagonal branch bifurcation successfully treated with a dedicated 2-stent technique utilizing bioresorbable vascular scaffolds, where the bifurcation angle did not strictly allow a T-stenting approach. We also propose a strategy to avoid or reduce scaffold overlap in the main branch, especially important in view of the bulkier size of these novel devices.

  16. Experimental study on effect of dexamethasone to the in-stent restenosis after vascular intervention

    International Nuclear Information System (INIS)

    Objective: To evaluate the effect of dexamethasone to the cultured rat thoracic aortic smooth muscle cells (SMC) in vitro, and explore the role on it's prevention and cure for the in-stent restenosis after vascular intervention. Methods: The rat thoracic aortic SMC were harvested and cultured for six to ten passages. The cultured SMC were synchronized and then restimutated to enter the cell cycle, and treated with incremental concentrations of dexamethasone or without dexamethasone as control. The proliferative assay was performed with MTT method in the different time points after treatment. RT-PCR was performed to assay the level of proliferating cell nuclear antigen (PCNA) mRNA. Results: 1. Dexamethasone progressively inhibited rat aortic SMC proliferation in a concentration-dependent fashion. The A value was statistically significant for different concentrations (F=36.02, P-6 and 10-5 mol/L (P=0.065) or between 10-11 mol/L and control group (P 0.567). 2. RT-PCR suggested dexamethasone significantly decreased rat aortic SMC PCNA mRNA transcription in a concentration-dependent fashion. Statistical analysis indicated F=15.407 and P-9 or 10-11 mol/L groups by post hoc analysis. Conclusions: Dexamethasone inhibits rat aortic SMC proliferation in a concentration- dependent fashion. The data suggest that effective action concentration is 10-7 mol/L with persistent time up to 96 hours or more. Dexamethasone may play the inhibit role to SMC at lower concentration with prolonging action time. (authors)

  17. Evaluation of electrospun PLLA/PEGDMA polymer coatings for vascular stent material.

    Science.gov (United States)

    Boodagh, Parnaz; Guo, Dong-Jie; Nagiah, Naveen; Tan, Wei

    2016-08-01

    The field of percutaneous coronary intervention has seen a plethora of advances over the past few decades, which have allowed for its development into safe and effective treatments for patients suffering from cardiovascular diseases. However, stent thrombosis and in-stent restenosis remain clinically significant problems. Herein, we describe the synthesis and characterization of fibrous polymer coatings on stent material nitinol, in the hopes of developing a more suitable stent surface to enhance re-endothelialization. Electrospinning technique was used to fabricate polyethylene glycol dimethacrylate/poly l-lactide acid (PEGDMA/PLLA) blend fiber substrate with tunable elasticity and hydrophilicity for use as coatings. Attachment of platelets and arterial smooth muscle cells (SMC) onto the coatings as well as the secretory effect of mesenchymal stem cells cultured on the coatings on the proliferation and migration of arterial endothelial cells and SMCs were assessed. It was demonstrated that electrospun PEGDMA/PLLA coating with 1:1 ratio of the components on the nitinol stent-reduced platelet and SMC attachment and increased stem cell secretory factors that enhance endothelial proliferation. We therefore postulate that the fibrous coating surface would possess enhanced biological compatibility of nitinol stents and hold the potential in preventing stent failure through restenosis and thrombosis. PMID:27137629

  18. Vascular response after implantation of coated and non-coated coronary stents

    NARCIS (Netherlands)

    S.H. Hofma (Sjoerd)

    2005-01-01

    textabstractHet doel van dit proefschrift was het bestuderen van de vaatwandreactie na interventies in de kransslagader. Hierbij werd gekeken naar acute en chronische vaatwandbeschadiging, endotheeldysfunctie en naar het gedrag van de nieuwste generatie stents, de zogenaamde “drug-eluting stents” (D

  19. MRI-compatible Nb–60Ta–2Zr alloy used for vascular stents: Haemocompatibility and its correlation with protein adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiu-Mei [School of Stomatology, China Medical University, 117 Nanjing North Street, Shenyang 110002 (China); Li, Hui-Zhe; Wang, Shao-Ping [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Huang, Hsun-Miao; Huang, Her-Hsiung [Biomaterials and Electrochemistry Lab, Department of Dentistry, National Yang-Ming University, Taipei City 112, Taiwan (China); Ai, Hong-Jun, E-mail: aih0620@yahoo.com.cn [School of Stomatology, China Medical University, 117 Nanjing North Street, Shenyang 110002 (China); Xu, Jian, E-mail: jianxu@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2014-09-01

    Nb–60Ta–2Zr is a newly developed MRI-compatible alloy used for vascular stents. In this work, its haemocompatibility was investigated, including platelet adhesion (lactate dehydrogenase activity), platelet activation (P-selectin expression), coagulation and haemolysis. For comparison, parallel assessments for these factors were performed for the niobium, tantalum, 316L stainless steel (316L SS) and L605 Co–Cr alloy (L605). In addition, albumin and fibrinogen were selected to examine the correlation of protein adsorption with platelet adhesion and metal surface properties. The propensity for platelet adhesion and activation on the Nb–60Ta–2Zr alloy was at nearly the same level as that for Nb and Ta but was slightly less than those of 316L SS and L605. The mitigated platelet adhesion and activation of the Nb–60Ta–2Zr alloy is associated with its decreased adsorption of fibrinogen. The Nb–60Ta–2Zr alloy has a longer clotting time and exhibits significantly superior thromboresistance than 316L SS and L605. Moreover, the haemolysis rate of the Nb–60Ta–2Zr alloy satisfies the bio-safety requirement of the ISO 10993–4 standard. The favourable haemocompatiblity of the Nb–60Ta–2Zr alloy provides evidence of its good biocompatibility and of its suitability as a candidate stent material. - Highlights: • The Nb–60Ta–2Zr alloy is less hydrophobic than the 316L SS and L605 alloy. • The Nb–60Ta–2Zr has slightly weak propensity for platelet adhesion and activation. • The Nb–60Ta–2Zr alloy results in a longer clotting time. • Haemolysis of Nb–60Ta–2Zr is slightly lower than that of 316L SS and L605. • The Nb–60Ta–2Zr alloy is a promising MRI-compatible stent material.

  20. A Combination of Drug-Eluting Stents and Bioresorbable Vascular Scaffolds in the Treatment of Multivessel Coronary Artery Disease

    Science.gov (United States)

    Al-Mamary, Ahmed; Zilio, Filippo; Napodano, Massimo

    2016-01-01

    Optimal management of multivessel coronary artery disease can be complex. We report a 67-year-old male patient who was admitted to the Padua University Hospital, Padua, Italy, in 2014 with a non-ST-elevation myocardial infarction. Coronary angiography showed diffuse multiple sub-occlusive lesions of the proximal and distal left coronary vessels involving a long segment of the vessel. On intravascular ultrasonography (IVUS), the left main artery was moderately diseased with critically stenotic and calcified branch ostia. A successful percutaneous coronary intervention using the T-stenting and small protrusion technique with two drug-eluting stents (DES) was performed on the left main artery and its main branches. Two bioresorbable vascular scaffolds were also deployed in overlap at the mid to distal segments of the left anterior descending artery and overlapping a previous DES at the proximal segment. The full expansion and apposition of the struts and scaffolds to the vessel wall without residual stenosis was confirmed by IVUS. PMID:27606119

  1. MRI-compatible Nb-60Ta-2Zr alloy for vascular stents: Electrochemical corrosion behavior in simulated plasma solution.

    Science.gov (United States)

    Li, Hui-Zhe; Zhao, Xu; Xu, Jian

    2015-11-01

    Using revised simulated body fluid (r-SBF), the electrochemical corrosion behavior of an Nb-60Ta-2Zr alloy for MRI compatible vascular stents was characterized in vitro. As indicated by XPS analysis, the surface passive oxide film of approximately 1.3nm thickness was identified as a mixture of Nb2O5, Ta2O5 and ZrO2 after immersion in the r-SBF. The Nb-60Ta-2Zr alloy manifests a low corrosion rate and high polarization resistance similar to pure Nb and Ta, as shown by the potentiodynamic polarization curves and EIS. Unlike 316L stainless steel and the L605 Co-Cr alloy, no localized corrosion has been detected. Semiconducting property of passive film on the Nb-60Ta-2Zr alloy was identified as the n-type, with growth mechanism of high-field controlled growth. The excellent corrosion resistance in simulated human blood enviroment renders the Nb-60Ta-2Zr alloy promising as stent candidate material.

  2. A Combination of Drug-Eluting Stents and Bioresorbable Vascular Scaffolds in the Treatment of Multivessel Coronary Artery Disease.

    Science.gov (United States)

    Al-Mamary, Ahmed; Zilio, Filippo; Napodano, Massimo

    2016-08-01

    Optimal management of multivessel coronary artery disease can be complex. We report a 67-year-old male patient who was admitted to the Padua University Hospital, Padua, Italy, in 2014 with a non-ST-elevation myocardial infarction. Coronary angiography showed diffuse multiple sub-occlusive lesions of the proximal and distal left coronary vessels involving a long segment of the vessel. On intravascular ultrasonography (IVUS), the left main artery was moderately diseased with critically stenotic and calcified branch ostia. A successful percutaneous coronary intervention using the T-stenting and small protrusion technique with two drug-eluting stents (DES) was performed on the left main artery and its main branches. Two bioresorbable vascular scaffolds were also deployed in overlap at the mid to distal segments of the left anterior descending artery and overlapping a previous DES at the proximal segment. The full expansion and apposition of the struts and scaffolds to the vessel wall without residual stenosis was confirmed by IVUS. PMID:27606119

  3. Surface characterization of polymer-drug modified vascular stents and intraocular lenses

    Science.gov (United States)

    Elachchabi, Amin

    Two of the most important medical devices in clinical use today are endoluminal stents and intraocular lenses (IOLs). In both devices, surface and interfacial properties are of basic importance in the development and clinical performance of these devices. Drug eluting stents have revolutionized the world of interventional cardiology. Research reported here was devoted to the design and development of new drug eluting stents wherein the metallic backbone is completely embedded in a polymeric matrix used also as a drug reservoir. This design, using silicone-drug compositions can lead to higher drug payloads, less tissue damage during angioplasty balloon/stent expansion, and the novel capability of delivering multiple drugs. The adhesion of the polymeric coating to the metallic stent is essential and has not been adequately reported previously. The adhesion of polydimethylsiloxane (PDMS) coatings to a stainless steel stent substrate was shown to be enhanced by the application of mixtures of tetra-n-propyl silicate, tetrabutyltitanate, tetra-2-methoxyethoxysilane, and 3-(trimethoxysilyl)propyl methacrylate coupling agents. Additionally, the effect of drug loading on the stress/strain properties of the polymeric coating is of basic importance. The tensile strength and percent elongation of dexamethasone loaded PDMS films was shown to remain satisfactory for stent coatings at low concentrations (less than 1%) but decreased as the concentrations of dexamethasone in PDMS was increased to 5%. The release of multiple therapeutic agents from PDMS coatings to reduce in-stent restenosis has not been previously reported. The release profile of Paclitaxel, dexamethasone 21-acetate, and their combination from PDMS coatings was studied using high precision liquid chromatography (HPLC). Although dexamethasone release was reduced by paclitaxel, paclitaxel release was unaffected by combination with dexamethasone. Paclitaxel release from the polymeric matrices was shown to inhibit

  4. Cyclic strain amplitude dictates the growth response of vascular smooth muscle cells in vitro: role in in-stent restenosis and inhibition with a sirolimus drug-eluting stent.

    Science.gov (United States)

    Colombo, Alberto; Guha, Shaunta; Mackle, Joseph N; Cahill, Paul A; Lally, Caitríona

    2013-08-01

    The putative effects of changes in mean strain and cyclic strain amplitude on vascular smooth muscle cell (vSMC) growth (proliferation and apoptosis) were examined. Subsequently, a quantitative measure of vSMC growth was obtained to determine the prolonged effect of changes in mechanical burden following bare-metal stent (BMS) and sirolimus drug-eluting stent (DES) deployment in vitro. Bovine aortic vSMCs were exposed to prolonged cyclic strain using a Flexercell(TM) Tension system and a novel Sylgard(TM) phantom vessel following stent implantation before the level of vSMC proliferation and apoptosis was assessed by FACS analysis, cell counting, and immunocytochemistry. Physiological cyclic strain (5%) decreased vSMC proliferation and increased apoptosis in a temporal manner. There was no significant difference in cell growth following exposure to varying mean strains with similar amplitude. In contrast, exposure to varying strain amplitudes with similar mean strains resulted in significant differences in cell proliferation and apoptosis. In parallel studies, the level of vSMC proliferation and cell survival was significantly increased within low amplitude, high mean strain regions of a phantom vessel following BMS implantation when compared to regions of higher strain amplitude upstream and downstream of the stent, respectively. Moreover, the level of vSMC growth within the stented region was significantly attenuated following implantation of a sirolimus-coated DES independent of significant changes in cell survival. Cyclic strain amplitude is an important regulator of vSMC growth capacity within a stent and is a target for inhibition using a sirolimus-coated DES.

  5. The value of primary vascular stents in management of early portal vein stenosis after liver transplantation.

    Science.gov (United States)

    Chang, Wen-Tsan; Kuo, Yu-Ting; Lee, King-Teh; Shih, Ming-Chen; Huang, Jian-Wei; Su, Wen-Lung; Chen, Chau-Yun; Huang, Yu-Ling; Wang, Shen-Nien; Chuang, Shih-Chang; Kuo, Kung-Kai; Chen, Jong-Shyone

    2016-03-01

    If portal vein stenosis (PVS) occurs within 1 month after liver transplantation (LT), especially within 1 week, it can be catastrophic and result in rapid loss of the grafts and mortality. Although surgical treatments have been considered standard treatment for PVS, patients are usually unable to receive operations or re-transplantations, because of their critical conditions and a shortage of grafts. Recently, primary percutaneous transhepatic portal vein stents (PTPS) were suggested as alternative and less-invasive treatments of PVS. However, because lethal complications may follow these primary stent placements for patients in early stages after LT, primary PTPS placements for patients suffering PVS 1 month after LT has been suggested. From November 2009 to July 2015, 38 consecutive adult patients underwent LT at our institution. Among them, six recipients suffered PVS within 1 month after LT. Technical success was achieved in all six patients. Clinical success was obtained in two of the four patients suffering PVS within 1 week after LT, and in the other two patients suffering PVS>1 week after LT. All surviving patients and their grafts were in good condition, and their stents remained patent. Our experience showed that primary PTPS placements can be used to effectively treat patients with PVS encountered within 1 month, and even within 1 week, after LT with acceptable short-term results. However, possible fatal complications should be kept in mind. Long-term results of these procedures need further follow-up. PMID:27106002

  6. Heparin and Vascular Endothelial Growth Factor Loaded Poly(L-lactide-co-caprolactone) Nanofiber Covered Stent-Graft for Aneurysm Treatment.

    Science.gov (United States)

    Wang, Jing; An, Qingzhu; Li, Dawei; Wu, Tong; Chen, Weiming; Sun, Binbin; El-Hamshary, Hany; Al-Deyab, Salem S; Zhu, Wei; Mo, Xiumei

    2015-11-01

    Restenosis caused by thrombopoiesis is one of the biggest hinders of endovascular stent-graft used in small-diameter vessels. Rapid endothelialization of the lumen of stent is a promising approach to prevent thrombosis. In this study, we aimed at loading heparin, a potent anticoagulants, and vascular endothelial growth factor (VEGF) into the core of poly(L-lactide-co-caprolactone) nanofiber via emulsion electrospinning. The nanofiber was covered on the stent and applied in the treatment of vascular diseases such as aneurysm. The morphologies of the emulsion electrospun nanofibers and core--shell structure were observed by scanning electron microscope and laser scanning confocal microscope. The release profiles of heparin and VEGF, degradation rate of nanofiber mats and cell proliferation in vitro were investigated. It was found that the release of both heparin and VEGF from the nanofiber lasted for more than 30 days without serious initial burst release. The degradation rate of nanofiber mats containing heparin and VEGF was faster than that of pure PLCL nanofiber mats. Moreover, the released VEGF could promote the proliferation of Pig iliac endothelial cells (PIECs) cultured on the nanofiber mat, which was of great benefit to stent endothelialization. The results of digital subtraction angiography (DSA) follow-up indicated the aneurysm was obliterated by separating the aneurysm dome from the blood circulation and the parent artery kept long-term patency. Results of the study demonstrated that the heparin and VEGF loaded nanofiber could provide an approach to fabricate covered stent-graft with properties of anticoagulation and induction of rapid endothelialization.

  7. Improved biocompatibility of poly(lactic-co-glycolic acid) orv and poly-L-lactic acid blended with nanoparticulate amorphous calcium phosphate in vascular stent applications.

    Science.gov (United States)

    Zheng, Xiaoxin; Wang, Yujue; Lan, Zhiyuan; Lyu, Yongnan; Feng, Gaoke; Zhang, Yipei; Tagusari, Shizu; Kislauskis, Edward; Robich, Michael P; McCarthy, Stephen; Sellke, Frank W; Laham, Roger; Jiang, Xuejun; Gu, Wei Wang; Wu, Tim

    2014-06-01

    Biodegradable polymers used as vascular stent coatings and stent platforms encounter a major challenge: biocompatibility in vivo, which plays an important role in in-stent restenosis (ISR). Co-formulating amorphous calcium phosphate (ACP) into poly(lactic-co-glycolic acid) (PLGA) or poly-L-lactic acid (PLLA) was investigated to address the issue. For stent coating applications, metal stents were coated with polyethylene-co-vinyl acetate/poly-n-butyl methacrylate (PEVA/PBMA), PLGA or PLGA/ACP composites, and implanted into rat aortas for one and three months. Comparing with both PEVA/PBMA and PLGA groups after one month, the results showed that stents coated with PLGA/ACP had significantly reduced restenosis (PLGA/ACP vs. PEVA/PBMA vs. PLGA: 21.24 +/- 2.59% vs. 27.54 +/- 1.19% vs. 32.12 +/- 3.93%, P < 0.05), reduced inflammation (1.25 +/- 0.35 vs. 1.77 +/- 0.38 vs. 2.30 +/- 0.21, P < 0.05) and increased speed of re-endothelialization (1.78 +/- 0.46 vs. 1.17 +/- 0.18 vs. 1.20 +/- 0.18, P < 0.05). After three months, the PLGA/ACP group still displayed lower inflammation score (1.33 +/- 0.33 vs. 2.27 +/- 0.55, P < 0.05) and higher endothelial scores (2.33 +/- 0.33 vs. 1.20 +/- 0.18, P < 0.05) as compared with the PEVA/PBMA group. Moreover, for stent platform applications, PLLA/ACP stent tube significantly reduced the inflammatory cells infiltration in the vessel walls of rabbit iliac arteries relative to their PLLA cohort (NF-kappaB-positive cells: 23.31 +/- 2.33/mm2 vs. 9.34 +/- 1.35/mm2, P < 0.05). No systemic biochemical or pathological evidence of toxicity was found in either PLGA/ACP or PLLA/ACP. The co-formulation of ACP into PLGA and PLLA resulted in improved biocompatibility without systemic toxicity.

  8. In vivo and in vitro characterization of poly(styrene-b-isobutylene-b-styrene) copolymer stent coatings for biostability, vascular compatibility and mechanical integrity.

    Science.gov (United States)

    Strickler, Fred; Richard, Robert; McFadden, Sharon; Lindquist, Jeff; Schwarz, Marlene C; Faust, Rudolf; Wilson, Gregory J; Boden, Mark

    2010-02-01

    The TAXUS Express 2 Paclitaxel Eluting Coronary Stent System employs a coating consisting of the thermoplastic elastomer, poly(styrene-b-isobutylene-b-styrene; SIBS), selected for its drug-eluting characteristics, vascular compatibility, mechanical properties, and biostability. This study was conducted to evaluate the impact of different SIBS (17-51 mole % styrene) compositions on mechanical properties, chemical stability, and vascular compatibility. Mechanical property (stress-strain measurements) and stability studies were conducted on polymer films with five different styrene contents (17, 24, 32, 39, and 51 mole %). The ultimate tensile strength did not change significantly with composition, but the elongation at break decreased with increased styrene content. A pulsatile fatigue test further confirmed the mechanical stability of SIBS up to 39 mole % styrene. The vascular compatibility of five different SIBS compositions was assessed using SIBS-only coated stents, in the coronary and carotid arteries in a porcine model study. The stability of the vessel wall, rate/degree of endothelialization, inflammation, and thrombus at timepoints from 30 to 180 days were evaluated. The results confirm vascular compatibility over the range of 17-51 mole % styrene.

  9. Assessment of vascular response after drug-eluting stents implantation in patients with diabetes mellitus: an optical coherence tomography sub-study of the J-DESsERT.

    Science.gov (United States)

    Kubo, Takashi; Akasaka, Takashi; Tanimoto, Takashi; Takano, Masamichi; Seino, Yoshitane; Nasu, Kenya; Itoh, Tomonori; Mizuno, Kyoichi; Okura, Hiroyuki; Shinke, Toshiro; Kotani, Jun-Ichi; Ito, Shigenori; Yokoi, Hiroyoshi; Muramatsu, Toshiya; Nakamura, Masato; Nanto, Shinsuke

    2016-04-01

    Even in the drug-eluting stent era, diabetes mellitus (DM) patients have high incidences of restenosis and repeat revascularization after percutaneous coronary intervention. The aim of this study was to compare vascular response after stent implantation between sirolimus-eluting stent (SES) and paclitaxel-eluting stent (PES) by using optical coherence tomography (OCT) in DM patients as well as in non-DM patients. In the Japan-Drug Eluting Stents Evaluation; a Randomized Trial (J-DESsERT), the OCT sub-study enrolled 75 patients who underwent 8 months follow-up imaging after SES or PES implantation. Mean neointimal hyperplasia (NIH) thickness was significantly thinner in SES than PES in the DM group (77 ± 47 vs. 201 ± 114 μm, p < 0.001) and in the non-DM group (84 ± 37 vs. 212 ± 128 μm, p < 0.001). Unevenness of NIH thickness in longitudinal axis was significantly smaller in SES than PES in the DM group (348 ± 191 vs. 726 ± 385 μm, p < 0.001) and in the non-DM group (344 ± 174 vs. 679 ± 314 μm, p < 0.001). The percentage of uncovered struts was significantly greater in SES than PES in the DM group (24 ± 4 vs. 9 ± 14 %, p < 0.001) and in the non-DM group (16 ± 16 vs. 3 ± 4 %, p = 0.002). Compared with PES, SES showed more potent NIH inhibition in DM patients as well as in non-DM patients. PMID:25630713

  10. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available Coronary Angioplasty Stent Placement Shawnee Mission Heart & Vascular Center, Shawnee Mission, Kansas February 19, 2009 Welcome to this OR-Live westbound cast presentation, live from Shawnee Mission Medical Center ...

  11. Auxetic coronary stent endoprosthesis

    DEFF Research Database (Denmark)

    Amin, Faisal; Ali, Murtaza Najabat; Ansari, Umar;

    2014-01-01

    BACKGROUND: Cardiovascular heart disease is one of the leading health issues in the present era and requires considerable health care resources to prevent it. The present study was focused on the development of a new coronary stent based on novel auxetic geometry which enables the stent to exhibit...... a negative Poisson's ratio. Commercially available coronary stents have isotropic properties, whereas the vascular system of the body shows anisotropic characteristics. This results in a mismatch between anisotropic-isotropic properties of the stent and arterial wall, and this in turn is not favorable...... for mechanical adhesion of the commercially available coronary stents with the arterial wall. It is believed that an auxetic coronary stent with inherent anisotropic mechanical properties and negative Poisson's ratio will have good mechanical adhesion with the arterial wall. METHODS: The auxetic design...

  12. Drug-eluting stents to prevent stent thrombosis and restenosis.

    Science.gov (United States)

    Im, Eui; Hong, Myeong-Ki

    2016-01-01

    Although first-generation drug-eluting stents (DES) have significantly reduced the risk of in-stent restenosis, they have also increased the long-term risk of stent thrombosis. This safety concern directly triggered the development of new generation DES, with innovations in stent platforms, polymers, and anti-proliferative drugs. Stent platform materials have evolved from stainless steel to cobalt or platinum-chromium alloys with an improved strut design. Drug-carrying polymers have become biocompatible or biodegradable and even polymer-free DES were introduced. New limus-family drugs (such as everolimus, zotarolimus or biolimus) were adopted to enhance stent performances. As a result, these new DES demonstrated superior vascular healing responses on intracoronary imaging studies and lower stent thrombotic events in actual patients. Recently, fully-bioresorbable stents (scaffolds) have been introduced, and expanding their applications. In this article, the important concepts and clinical results of new generation DES and bioresorbable scaffolds are described.

  13. Drug-eluting stents to prevent stent thrombosis and restenosis.

    Science.gov (United States)

    Im, Eui; Hong, Myeong-Ki

    2016-01-01

    Although first-generation drug-eluting stents (DES) have significantly reduced the risk of in-stent restenosis, they have also increased the long-term risk of stent thrombosis. This safety concern directly triggered the development of new generation DES, with innovations in stent platforms, polymers, and anti-proliferative drugs. Stent platform materials have evolved from stainless steel to cobalt or platinum-chromium alloys with an improved strut design. Drug-carrying polymers have become biocompatible or biodegradable and even polymer-free DES were introduced. New limus-family drugs (such as everolimus, zotarolimus or biolimus) were adopted to enhance stent performances. As a result, these new DES demonstrated superior vascular healing responses on intracoronary imaging studies and lower stent thrombotic events in actual patients. Recently, fully-bioresorbable stents (scaffolds) have been introduced, and expanding their applications. In this article, the important concepts and clinical results of new generation DES and bioresorbable scaffolds are described. PMID:26567863

  14. Arterial healing following primary PCI using the Absorb everolimus-eluting bioresorbable vascular scaffold (Absorb BVS) versus the durable polymer everolimus-eluting metallic stent (XIENCE) in patients with acute ST-elevation myocardial infarction

    DEFF Research Database (Denmark)

    Räber, Lorenz; Onuma, Yoshinobu; Brugaletta, Salvatore;

    2015-01-01

    AIMS: The Absorb bioresorbable vascular scaffold (Absorb BVS) provides similar clinical outcomes compared with a durable polymer-based everolimus-eluting metallic stent (EES) in stable coronary artery disease patients. ST-elevation myocardial infarction (STEMI) lesions have been associated...

  15. Incidence and Potential Mechanism(s) of Post-Procedural Rise of Cardiac Biomarker in Patients With Coronary Artery Narrowing After Implantation of an Everolimus-Eluting Bioresorbable Vascular Scaffold or Everolimus-Eluting Metallic Stent

    DEFF Research Database (Denmark)

    Ishibashi, Yuki; Muramatsu, Takashi; Nakatani, Shimpei;

    2015-01-01

    to Compare the Safety, Efficacy, and Performance of Absorb Everolimus Eluting Bioresorbable Vascular Scaffold System Against Xience Everolimus Eluting Coronary Stent System in the Treatment of Subjects With Ischemic Heart Disease Caused by De Novo Native Coronary Artery Lesions [ABSORB II]; NCT01425281)....

  16. Angioplasty and Vascular Stenting

    Science.gov (United States)

    ... throughout the body, including: narrowing of large arteries (aorta and its branches) due to atherosclerosis , or hardening ... saturated fat, exercising and not smoking. Individuals with diabetes, high blood pressure and/or high cholesterol need ...

  17. Enhanced in Vitro and in Vivo Performance of Mg-Zn-Y-Nd Alloy Achieved with APTES Pretreatment for Drug-Eluting Vascular Stent Application.

    Science.gov (United States)

    Liu, Jing; Zheng, Bo; Wang, Pei; Wang, Xingang; Zhang, Bin; Shi, Qiuping; Xi, Tingfei; Chen, Ming; Guan, Shaokang

    2016-07-20

    Bioabsorbable magnesium alloys are becoming prominent as temporary functional implants, as they avoid the risks generated by permanent metallic implants such as persistent inflammation and late restenosis. Nevertheless, the overfast corrosion of Mg alloys under physiological conditions hinders their wider application as medical implant materials. Here we investigate a simple one-step process to introduce a cross-linked 3-amino-propyltrimethoxysilane (APTES) silane physical barrier layer on the surface of Mg-Zn-Y-Nd alloys prior to electrostatic spraying with rapamycin-eluting poly(lactic-co-glycolic acid) (PLGA) layer. Surface microstructure was characterized by scanning electron microscope and Fourier transform infrared spectroscopy. Nanoscratch test verified the superior adhesion strength of PLGA coating in the group pretreated with APTES. Electrochemical tests combined with long-term immersion results suggested that the preferable in vitro anticorrosion behavior could be achieved by dense APTES barrier. Cell morphology and proliferation data demonstrated that APTES pretreated group resulted in remarkably preferable compatibility for both human umbilical vein endothelial cells and vascular smooth muscle cells. On the basis of excellent in vitro mechenical property, the animal study on the APTES pretreated Mg-Zn-Y-Nd stent implanted into porcine coronary arteries confirmed benign tissue compatibility as well as re-endothelialization without thrombogenesis or in-stent restenosis at six-month followup. PMID:27331417

  18. Polymers for Cardiovascular Stent Coatings

    Directory of Open Access Journals (Sweden)

    Anne Strohbach

    2015-01-01

    Full Text Available Polymers have found widespread applications in cardiology, in particular in coronary vascular intervention as stent platforms (scaffolds and coating matrices for drug-eluting stents. Apart from permanent polymers, current research is focussing on biodegradable polymers. Since they degrade once their function is fulfilled, their use might contribute to the reduction of adverse events like in-stent restenosis, late stent-thrombosis, and hypersensitivity reactions. After reviewing current literature concerning polymers used for cardiovascular applications, this review deals with parameters of tissue and blood cell functions which should be considered to evaluate biocompatibility of stent polymers in order to enhance physiological appropriate properties. The properties of the substrate on which vascular cells are placed can have a large impact on cell morphology, differentiation, motility, and fate. Finally, methods to assess these parameters under physiological conditions will be summarized.

  19. Intimal hyperplasia and vascular remodeling after everolimus-eluting and sirolimus-eluting stent implantation in diabetic patients the randomized diabetes and drug-eluting stent (DiabeDES) IV intravascular ultrasound trial

    DEFF Research Database (Denmark)

    Antonsen, Lisbeth; Maeng, Michael; Thayssen, Per;

    2013-01-01

    OBJECTIVE: To evaluate the effects of the everolimus-eluting Xience™/Promus™ stent (EES) and the sirolimus-eluting Cypher™ stent (SES) on intimal hyperplasia (IH) in diabetic patients. BACKGROUND: Patients with diabetes mellitus have increased risk of in-stent restenosis after coronary stent...... implantation due to intimal hyperplasia (IH). METHODS: In a sub study of the Randomized Comparison of Everolimus-Eluting and Sirolimus-Eluting Stents in Patients Treated with Percutaneous Coronary Intervention (SORT OUT IV trial), serial intravascular ultrasound (IVUS) 10-month follow-up data were available...... in 88 patients, including 48 EES and 40 SES treated patients. IVUS endpoints included IH volume, in-stent % volume obstruction and changes in external elastic membrane (EEM) volume. RESULTS: Compared with the SES group, IH volume was increased in the EES group [median (interquartile range): 2.8 mm(3) (0...

  20. Histocompatibility of vascular stents constructed using different biomaterials%不同生物材料构建血管支架的组织相容性

    Institute of Scientific and Technical Information of China (English)

    赵广建; 赵耀

    2011-01-01

    背景:组织工程支架已成为近年来研究的热点,不同材料构建的组织工程血管支架的特点各异,植入后的生物相容性、感染、再狭窄是临床上面临的难点与重要研究课题.目的:文章综述了不同材料构建的组织工程血管支架的特点和生物相容性等的研究进展,以便寻找临床最佳的生物材料支架.方法:应用计算机检索CNKI和PubMed数据库中2002-01/2010-12关于细菌生物膜耐药机制的文章,在标题和摘要中以"组织工程,血管支架,相容性,感染,再狭窄"或"Tissue engineering,stents,compatibility,infection,restenosis"为检索词进行检索.选择文章内容与血管支架的特点和生物相容性相关,同一领域文献则选择近期发表或发表在权威杂志文章.初检得到285篇文献,根据纳入标准选择23篇文章进行综述.结果与结论:天然材料包含有生物信息(如特殊的氨基酸序列),可促进细胞吸附或使细胞保留分化功能,人工合成材料的优点是它们的强度、降解速度、微结构和渗透性均可在生产过程中进行控制;若生物材料和高分子可降解材料相结合,将两者按照一定的方法组合构建成一种复合基质,发挥两者各自的优势,便能更好地满足血管组织工程的要求,构建出性能良好的组织工程化血管.%BACKGROUND: Tissue-engineered scaffold has become a research hotspot in recent years. Tissue-engineered vascular stents prepared by different biomaterials have their own characteristics. Post-implant biocompatibility, infection, and restenosis are the difficulties and important topics in clinic.OBJECTIVE: To review the characteristics and biocompatibility of tissue-engineered vascular stents prepared by different biomaterials so as to find an ideal biomaterial stent in clinic.METHODS: A computer based search of CNKI and PubMed was performed to find articles regarding biofilm resistance mechanisms published from 2002-01 to 2010

  1. Percutaneous Stent-Graft Repair of Anastomotic Pseudoaneurysms following Vascular Bypass Procedures: A Report of Two Cases

    Directory of Open Access Journals (Sweden)

    John Rundback

    2013-01-01

    Full Text Available Anastomotic pseudoaneurysms are common entities following vascular bypass procedures and, if left untreated, serious complications such as thromboses, infection, and rupture can frequently occur. Therefore, attempts to employ various methods of repair have been utilized in treating anastomotic pseudoaneurysms to maximize operational success and future risk reduction. Herein, the authors report two cases of anastomotic pseudoaneurysms which were repaired percutaneously utilizing a combination of strategies such as careful preoperational image planning, multiple commercially available devices, and secondary embolization techniques.

  2. Bronchial stents

    Directory of Open Access Journals (Sweden)

    Ibrahim Emad

    2006-01-01

    Full Text Available Bronchial stents are mostly used as a Palliative relief of symptoms often caused by airway obstruction, It is also used for sealing of stump fistulas after pneumonectomy and dehiscence after bronchoplastic operations. Advances in airway prosthetics have provided a variety of silicone stents, expandable metal stents, and pneumatic dilators, enabling the correction of increasingly complex anatomical problems. Several series have been published describing the application and results of these techniques. This manuscript reviews the historical development of stents, types, indication, outcome, and complications. Alternative therapies for tracheobronchial stenting were also reviewed

  3. Basic Knowledge about Metal Stent Development

    OpenAIRE

    Jeong, Seok

    2016-01-01

    Biliary self-expandable metal stents (SEMS), a group of non-vascular stents, have been used in the palliative management of biliary obstruction around the world. However, there are still unmet needs in the clinical application of biliary SEMS. Comprehensive understanding of the SEMS is required to resolve the drawbacks and difficulties of metal stent development. The basic structure of SEMS, including the materials and knitting methods of metal wires, covering materials, and radiopaque marker...

  4. Dual Delivery of BMP-2 and bFGF from a New Nano-Composite Scaffold, Loaded with Vascular Stents for Large-Size Mandibular Defect Regeneration

    Directory of Open Access Journals (Sweden)

    Hang Zhao

    2013-06-01

    Full Text Available The aim of this study was to investigate the feasibility and advantages of the dual delivery of bone morphogenetic protein-2 (BMP-2 and basic fibroblast growth factor (bFGF from nano-composite scaffolds (PLGA/PCL/nHA loaded with vascular stents (PLCL/Col/nHA for large bone defect regeneration in rabbit mandibles. Thirty-six large bone defects were repaired in rabbits using engineering bone composed of allogeneic bone marrow mesenchymal stem cells (BMSCs, bFGF, BMP-2 and scaffolds composed of PLGA/PCL/nHA loaded with PLCL/Col/nHA. The experiments were divided into six groups: BMSCs/bFGF/BMP-2/scaffold, BMSCs/BMP-2/scaffold, BMSCs/bFGF/scaffold, BMSCs/scaffold, scaffold alone and no treatment. Sodium alginate hydrogel was used as the carrier for BMP-2 and bFGF and its features, including gelling, degradation and controlled release properties, was detected by the determination of gelation and degradation time coupled with a controlled release study of bovine serum albumin (BSA. AlamarBlue assay and alkaline phosphatase (ALP activity were used to evaluate the proliferation and osteogenic differentiation of BMSCs in different groups. X-ray and histological examinations of the samples were performed after 4 and 12 weeks post-implantation to clarify new bone formation in the mandible defects. The results verified that the use of sodium alginate hydrogel as a controlled release carrier has good sustained release ability, and the combined application of bFGF and BMP-2 could significantly promote the proliferation and osteogenic differentiation of BMSCs (p < 0.05 or p < 0.01. In addition, X-ray and histological examinations of the samples exhibited that the dual release group had significantly higher bone formation than the other groups. The above results indicate that the delivery of both growth factors could enhance new bone formation and vascularization compared with delivery of BMP-2 or bFGF alone, and may supply a promising way of repairing large

  5. Simulation of stent deployment in a realistic human coronary artery

    NARCIS (Netherlands)

    F.J.H. Gijsen (Frank); F. Migliavacca (Francesco); S. Schievano (Silvia); L. Socci (Laura); L. Petrini (Lorenza); A. Thury (Attila); J.J. Wentzel (Jolanda); A.F.W. van der Steen (Ton); P.W.J.C. Serruys (Patrick); G. Dubini (Gabriele)

    2008-01-01

    textabstractBackground: The process of restenosis after a stenting procedure is related to local biomechanical environment. Arterial wall stresses caused by the interaction of the stent with the vascular wall and possibly stress induced stent strut fracture are two important parameters. The knowledg

  6. Late stent malapposition and marked positive vessel remodeling after sirolimus-eluting coronary stent implantation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; QIAN Ju-ying; GE Jun-bo

    2006-01-01

    @@ It has been reported that positive remodeling, regression of neointimal hyperplasia, and late malapposition are associated with brachytherapy, one of the approaches to prevent first-time and recurrent in-stent restenosis.1,2 Recently, some drug-eluting stents have been demonstrated to dramatically reduce restenosis rates.3,4 Despite these promising results, these drug-eluting stents may have the same potential risks as brachytherapy, with some similarities between the 2 technologies in anti- proliferative effects on vascular smooth muscle cells and endothelial cells. We reported a case of late stent malapposition and marked positive vessel remodeling after sirolimus-eluting coronary stent implantation.

  7. Peri-stent contrast staining, major evaginations and severe malapposition after biolimus-eluting stent implantation

    DEFF Research Database (Denmark)

    Antonsen, Lisbeth; Thayssen, Per; Jensen, Lisette Okkels

    2014-01-01

    Peri-stent contrast staining and late acquired malapposition represent pathological vessel wall healing patterns following percutaneous coronary intervention with stent implantation. Earlier studies have described these abnormal vessel wall responses commonly present after implantation of first......-generation drug-eluting stents. These coronary vascular changes can cause flow disturbance and thereby dispose for later thrombotic events. This case report, based on coronary optical frequency domain imaging, describes peri-stent contrast staining, major evaginations and severe malapposition occurring 18months...... after third-generation biolimus-eluting stent implantation....

  8. Influence of strut cross-section of stents on local hemodynamics in stented arteries

    Science.gov (United States)

    Jiang, Yongfei; Zhang, Jun; Zhao, Wanhua

    2016-05-01

    Stenting is a very effective treatment for stenotic vascular diseases, but vascular geometries altered by stent implantation may lead to flow disturbances which play an important role in the initiation and progression of restenosis, especially in the near wall in stented arterial regions. So stent designs have become one of the indispensable factors needed to be considered for reducing the flow disturbances. In this paper, the structural designs of strut cross-section are considered as an aspect of stent designs to be studied in details. Six virtual stents with different strut cross-section are designed for deployments in the same ideal arterial model. Computational fluid dynamics (CFD) methods are performed to study how the shape and the aspect ratio (AR) of strut cross-section modified the local hemodynamics in the stented segments. The results indicate that stents with different strut cross-sections have different influence on the hemodynamics. Stents with streamlined cross-sectional struts for circular arc or elliptical arc can significantly enhance wall shear stress (WSS) in the stented segments, and reduce the flow disturbances around stent struts. The performances of stents with streamlined cross-sectional struts are better than that of stents with non-streamlined cross-sectional struts for rectangle. The results also show that stents with a larger AR cross-section are more conductive to improve the blood flow. The present study provides an understanding of the flow physics in the vicinity of stent struts and indicates that the shape and AR of strut cross-section ought to be considered as important factors to minimize flow disturbance in stent designs.

  9. Aortic stenting.

    Science.gov (United States)

    Droc, Ionel; Calinescu, Francisca Blanca; Droc, Gabriela; Blaj, Catalin; Dammrau, Rolf

    2015-01-01

    The approach to aortic pathology is nowadays more and more endovascular at both thoracic and abdominal levels. Thoracic stenting has gained worldwide acceptance as first intention to treat pathologies of the descending thoracic aorta. Indications have been extended to aortic arch aneurysms and also to diseases of the ascending aorta. The current devices in use for thoracic endovascular repair (TEVAR) are Medtronic Valiant, Gore TAG, Cook Tx2 and Jotec. The choice of the endograft depends on the thoracic aortic pathology and the anatomical suitability. The technological evolution of the abdominal aortic endografts was very rapid, arriving now at the fourth generation. We report the results of 55 elective cases of endovascular abdominal aortic repair (EVAR) performed in two vascular surgical centers in Romania and Germany. The prostheses used were 16 E-vita Abdominal XT, 12 Excluder, eight Talent, seven PowerLink, three Endurant and nine custom-made, fenestrated or branched from Jotec. The mean follow-up was 18 months with CT-scan, duplex ultrasound and contrast-enhanced ultrasound. The mortality was 2%. EVAR tends to become the gold standard for abdominal aortic aneurysm repair. Technological development of the devices with lowest profile introduction systems will permit to extend the anatomical indications to new frontiers. PMID:26200430

  10. Simulation of stent deployment in a realistic human coronary artery

    OpenAIRE

    van der Steen Anton FW; Wentzel Jolanda J; Thury Attila; Petrini Lorenza; Socci Laura; Schievano Silvia; Migliavacca Francesco; Gijsen Frank JH; Serruys Patrick WS; Dubini Gabriele

    2008-01-01

    Abstract Background The process of restenosis after a stenting procedure is related to local biomechanical environment. Arterial wall stresses caused by the interaction of the stent with the vascular wall and possibly stress induced stent strut fracture are two important parameters. The knowledge of these parameters after stent deployment in a patient derived 3D reconstruction of a diseased coronary artery might give insights in the understanding of the process of restenosis. Methods 3D recon...

  11. 上腔静脉阻塞综合征的血管内支架治疗%Superior Vana Cava Syndrome: A Therapy by Intra-vascular Stenting

    Institute of Scientific and Technical Information of China (English)

    官泳松; 汪小舟; 黄明亮; 张华山

    2003-01-01

    Objective To study the techniques and clinical applications of intra-vascular stenting in the treatment of superior vana cava oblit-eration syndrome (SVS).Methods In 9 cases of SVS, primary lesions were all confirmed as malignancy ( primary pulmonary carcinoma of right upperlobe) histolo-pathologically. By route of right femoral vein, SVS catheterization and DSA was made. The length of the stricturesand the diameters of normal superior vana cavae (SVC) were measured for the choice of appropriate stents. The option of stent di-ameter is 10% larger than that of normal SVCs. The upper and lower ends of the stent should be 1 - 2 cm protruding from the endsof the stricture. The stent was dilated with a balloon after its successful placement. Therapy of original lesions was continued to-gether with anticoagulant. Stents were observed about their positions by fluoroscopy or chest films, and about patency of SVC byDoppler.Results After the placement of a stent, DSA revealed the contrast media in the SVCs passed along smoothly, diameters of SVCsalmost normal, collateral branches diminished remarkably. Average SVC pressure was decreased from 26.4 cmH2O before theplacement down to 15.7 cmH2 O, with an obvious difference (P < 0.01 = by statistics. Related clinical symptoms and signs disap-peared or relieved. Subsidised were swelling of head and neck, upper extremities and chest. Excretion of urine increased. Gor-geous superficial veins in the chest could not be detected any more.Conclusion The therapy of intra-vascular stenting to treat SVS is microinvasive, simple and effective.%目的 探讨血管内支架治疗上腔静脉阻塞综合征的技术和临床应用效果.方法 9例上腔静脉阻塞综合征患者,原发病灶均由病理组织学诊断为恶性肿瘤(右上肺中央型肺癌).行右股静脉穿刺,在造影像上测量狭窄长度及正常上腔静脉直径,选择适当支架,原则上支架直径应超过正常上腔静脉直径10%,

  12. Computational Study of Axial Fatigue for Peripheral Nitinol Stents

    Science.gov (United States)

    Meoli, Alessio; Dordoni, Elena; Petrini, Lorenza; Migliavacca, Francesco; Dubini, Gabriele; Pennati, Giancarlo

    2014-07-01

    Despite their success as primary treatment for vascular diseases, Nitinol peripheral stents are still affected by complications related to fatigue failure. Hip and knee movements during daily activities produce large and cyclic deformations of the superficial femoral artery, that concomitant to the effects of pulsatile blood pressure, may cause fatigue failure in the stent. Fatigue failure typically occurs in cases of very extended lesions, which often require the use of two or more overlapping stents. In this study, finite element models were used to study the fatigue behavior of Nitinol stents when subjected to cyclic axial compression in different conditions. A specific commercial Nitinol stent was chosen for the analysis and subjected to cyclic axial compression typical of the femoral vascular region. Three different configurations were investigated: stent alone, stent deployed in a tube, and two overlapping stents deployed in a tube. Results confirm that stent oversizing has an influence in determining both the mean and amplitude strains induced in the stent and plays an important role in determining the fatigue response of Nitinol stents. In case of overlapping stents, numerical results suggest higher amplitude strains concentrate in the region close to the overlapping portion where the abrupt change in stiffness causes higher cyclic compression. These findings help to explain the high incidence of stent fractures observed in various clinical trials located close to the overlapping portion.

  13. The Integrity bare-metal stent made by continuous sinusoid technology.

    Science.gov (United States)

    Turco, Mark A

    2011-05-01

    The Integrity Coronary Stent System (Medtronic Vascular, CA, USA) is a low-profile, open-cell, cobalt-chromium-alloy advanced bare-metal iteration of the well-known Driver/Micro-Driver Coronary Stent System (Medtronic Vascular). The Integrity stent is made with a process called continuous sinusoid technology. This process allows stent construction via wrapping a single thin strand of wire around a mandrel in a sinusoid configuration, with laser fusion of adjacent crowns. The wire-forming process and fusion pattern provide the stent with a continuous preferential bending plane, intended to allow easier access to, and smoother tracking within, distal and tortuous vessels while radial strength is maintained. Continuous sinusoid technology represents innovation in the design of stent platforms and will provide a future stent platform for newer technology, including drug-eluting stent platforms, drug-filled stents and core wire stents. PMID:21542702

  14. Technical overview on the MiStent coronary stent.

    Science.gov (United States)

    McCLAIN, James B; Carlyle, Wenda C; Donohoe, Dennis J; Ormiston, John A

    2016-10-01

    Drug-eluting stents (DES) have dramatically improved the long-term efficacy of percutaneous coronary intervention (PCI). Over the last decade there have been numerous advances in DES platforms, however, all but one currently approved DES in the United States and many of the approved DES worldwide still have 3 common features: a metal stent platform, an anti-proliferative drug, and a permanent polymer. In this context, the polymer is critical to control drug release, but the polymer serves no purpose after the drug is eluted. While designed to be completely biocompatible, synthetic polymers have the potential to illicit an inflammatory response within the vessel including but not limited to delayed healing and hypersensitivity. Adverse vascular reactions to these polymers have been implicated as a cause of very late stent thrombosis, ongoing intimal hyperplasia and late "catch-up" in addition to neoatherosclerosis. To avoid the long-term risks associated with prolonged polymer exposure, DES with bioabsorbable polymers have been developed. The MiStent® Sirolimus-Eluting Absorbable Polymer Coronary Stent System (MiStent SES) (MiCell Technologies, Durham, NC, USA) combines crystalline sirolimus, a rapidly absorbing polylactide-co-glycolic acid (PLGA) coating and a thin-strut cobalt chromium alloy stent platform (Genius MAGIC® Stent System, EuroCor GmbH, Germany). MiCell's supercritical fluid technology allows a rigorously controlled, solvent-free drug and polymer coating to be applied to a bare-metal stent. This solvent-free application of drug uniquely allows a crystalline form of sirolimus to be used on the MiStent SES potentially providing improved clinical benefits. It avoids the uncontrolled burst of drug seen with other DES, provides uniform drug delivery around and between the stent struts, and allows the anti-inflammatory and anti-restenotic drug (sirolimus) to be present in the tissue through the entire polymer absorption period and for months after the

  15. Artificial Coronary Vascular Stents Fabrication Using the Biodegradable Material Compounds: PLA-PGA-co-Chitosan%可完全生物降解材料聚乳酸-聚羟基乙酸复合壳聚糖在人工心血管支架制备中的应用

    Institute of Scientific and Technical Information of China (English)

    郭清奎; 吕志前

    2011-01-01

    The first two generation scaffolds, bare metal stents (BMS) and drug eluting stents (DES) , have been widely used in the treatment of coronary heart diseases. However, long term incidences of major adverse cardiovascular events and revascularization treatments are still high because of in-stent re-stenosis and thrombosis. These may be caused by chronic inflammations and vascular wall damages due to persistent metal stents stimulation. The eluting drugs within metal stents could also disturb normal growth of vascular endothelial cell, intima, tunica media, smooth muscle and epimysium. Therefore, several fully biodegradable scaffolds and drug carried stents had been manufactured using polymers polyester, polycarbonate and polyphosphate, etc. Recently, tissue and blood compatibility securities of present implanted artificial cardiovascular stents manufactured with copolymer materials had been confirmed. However, these stents could not meet the clinical demands because of the respective problems of degradation, material rigidity, flexibility and nonuniformity of support strength. This paper reviews the current and perspective application of polylactic acid (PLA) , polyglycolic acid (PGA) and chitosan in the fabrication of fully biodegradable artificial coronary vascular scaffolds.%裸金属支架(bare metal stents,BMS)和涂层支架(drug eluting stents,DES)介入治疗冠心病已在临床广泛应用,但由于金属支架的异物刺激或携带药物的干扰容易引起支架内再狭窄和血管栓塞,由聚酯、聚碳酸酐及聚磷酸酯等高分子材料制备的完全可生物降解吸收支架及药物洗脱支架应运而生.目前由共聚物材料制备的人工心血管植入支架的安全性、组织及血液相容性已得到证实,然而这些支架具有各自的问题,如降解的速度、材料的柔韧度、硬度以及支撑力不均一等,尚不能满足实际应用的要求.本文就聚乳酸(polylactic acid

  16. Axial stent strut angle influences wall shear stress after stent implantation: analysis using 3D computational fluid dynamics models of stent foreshortening

    Directory of Open Access Journals (Sweden)

    Warltier David C

    2005-10-01

    Full Text Available Abstract Introduction The success of vascular stents in the restoration of blood flow is limited by restenosis. Recent data generated from computational fluid dynamics (CFD models suggest that the vascular geometry created by an implanted stent causes local alterations in wall shear stress (WSS that are associated with neointimal hyperplasia (NH. Foreshortening is a potential limitation of stent design that may affect stent performance and the rate of restenosis. The angle created between axially aligned stent struts and the principal direction of blood flow varies with the degree to which the stent foreshortens after implantation. Methods In the current investigation, we tested the hypothesis that stent foreshortening adversely influences the distribution of WSS and WSS gradients using time-dependent 3D CFD simulations of normal arteries based on canine coronary artery measurements of diameter and blood flow. WSS and WSS gradients were calculated using conventional techniques in ideal (16 mm and progressively foreshortened (14 and 12 mm stented computational vessels. Results Stent foreshortening increased the intrastrut area of the luminal surface exposed to low WSS and elevated spatial WSS gradients. Progressive degrees of stent foreshortening were also associated with strut misalignment relative to the direction of blood flow as indicated by analysis of near-wall velocity vectors. Conclusion The current results suggest that foreshortening may predispose the stented vessel to a higher risk of neointimal hyperplasia.

  17. 聚乳酸在血管支架中的应用及研究进展%Research advances of polylactic acid and its application in vascular stents

    Institute of Scientific and Technical Information of China (English)

    毛岳峰; 朱晒红; 王国慧

    2008-01-01

    聚乳酸及其共聚物是一类可生物降解的高分子聚合材料,不仅具有优良的机械性能和化学稳定性,还具备良好的生物相容性、可吸收性以及可降解性,因此被广泛应用于医学领域.主要介绍聚乳酸在血管支架方面的应用和研究进展.%Polylactic acid (PLA) and its copolymer are biodegradable polymer materials which are widely used in the medical field because of their excellent mechanical properties, chemical stability, good biocompatibility, and biodegradability. In this paper, research advances in the study on polylactic acid and its application in vascular stent are discussed.

  18. Effect of Lowering Asymmetric Dimethylarginine (ADMA on Vascular Pathology in Atherosclerotic ApoE-Deficient Mice with Reduced Renal Mass

    Directory of Open Access Journals (Sweden)

    Johannes Jacobi

    2014-03-01

    Full Text Available The purpose of the work was to study the impact of the endogenous nitric oxide synthase (NOS inhibitor asymmetric dimethylarginine (ADMA and its degrading enzyme, dimethylarginine dimethylaminohydrolase (DDAH1, on atherosclerosis in subtotally nephrectomized (SNX ApoE-deficient mice. Male DDAH1 transgenic mice (TG, n = 39 and C57Bl/6J wild-type littermates (WT, n = 27 with or without the deletion of the ApoE gene underwent SNX at the age of eight weeks. Animals were sacrificed at 12 months of age, and blood chemistry, as well as the extent of atherosclerosis within the entire aorta were analyzed. Sham treated (no renal mass reduction ApoE-competent DDAH1 transgenic and wild-type littermates (n = 11 served as a control group. Overexpression of DDAH1 was associated with significantly lower ADMA levels in all treatment groups. Surprisingly, SNX mice did not exhibit higher ADMA levels compared to sham treated control mice. Furthermore, the degree of atherosclerosis in ApoE-deficient mice with SNX was similar in mice with or without overexpression of DDAH1. Overexpression of the ADMA degrading enzyme, DDAH1, did not ameliorate atherosclerosis in ApoE-deficient SNX mice. Furthermore, SNX in mice had no impact on ADMA levels, suggesting a minor role of this molecule in chronic kidney disease (CKD in this mouse model.

  19. Basic Knowledge about Metal Stent Development.

    Science.gov (United States)

    Jeong, Seok

    2016-03-01

    Biliary self-expandable metal stents (SEMS), a group of non-vascular stents, have been used in the palliative management of biliary obstruction around the world. However, there are still unmet needs in the clinical application of biliary SEMS. Comprehensive understanding of the SEMS is required to resolve the drawbacks and difficulties of metal stent development. The basic structure of SEMS, including the materials and knitting methods of metal wires, covering materials, and radiopaque markers, are discussed in this review. What we know about the physical and mechanical properties of the SEMS is very important. With an understanding of the basic knowledge of metal stents, hurdles such as stent occlusion, migration, and kinking can be overcome to develop more ideal SEMS. PMID:27000423

  20. 超声血管增强技术在布-加综合征支架置入术后疗效评估中的应用%Application of vascular enhancement technology in the evaluation of therapeutic efficacy of stenting for Budd-Chiari syndrome

    Institute of Scientific and Technical Information of China (English)

    王荣; 王兴田; 亓培君; 祖茂衡

    2013-01-01

    目的 探讨超声血管增强技术(VET)在布-加综合征(BCS)支架置入术后疗效评估中的应用价值.方法 对39例BCS置入支架患者共41个支架进行二维超声、彩色多普勒及VET检查,存储支架及所在血管的静态及动态图像,比较血管内支架的二维与VET图像质量.对超声检查发现的支架狭窄的患者行数字减影血管造影(DSA)检查,测量支架内血栓范围,并与VET检查结果进行比较.结果 VET技术显示血管内支架图像质量评分高于二维超声,二者比较差异有统计学意义.VET显示的支架内血栓范围与DSA结果相近.结论 VET可改善血管内支架的清晰度,与彩色多普勒相结合,提高了超声在BCS支架置入术后疗效评估中的应用价值.%Objective To explore the value of vascular enhancement technology (VET) in the evaluation of therapeutic efficacy of stenting for Budd-Chiari syndrome (BCS).Methods Two-dimensional ultrasound,color Doppler and VET were performed on 39 BCS patients with 41 stents,the static and dynamic images of stents and vessels with stents were stored.VET and two-dimensional ultrasound imaging quality of intravascular stent were compared.Patients with stent stenosis found by ultrasound were examined by digital subtraction angiography(DSA).The ranges of stent thrombosis were measured by DSA and VET and the difference was compared.Results VET image quality scores of endovascular stent were higher than those of the two-dimensional ultrasound,the difference was statistically significant.The ranges of stent thrombosis measured by VET were similar to DSA.Conclusions VET can improve the clarity of intravascular stents.VET and color Doppler can enhance the clinical value of ultrasound in the evaluation of therapeutic efficacy of stenting for BCS.

  1. Carotid stenting and endarterectomy.

    Science.gov (United States)

    Yip, Hon-Kan; Sung, Pei-Hsun; Wu, Chiung-Jen; Yu, Cheuk-Man

    2016-07-01

    Stroke, either ischemic or hemorrhagic, remains the second commonest cause of death worldwide in the last decade. Etiologies for ischemic stroke (IS) vary widely. Atherothrombotic occlusion is an essential cause to which carotid artery stenosis (CAS) is a major contributor. Administration of anti-platelet agent to patients with CAS has been shown to reduce incidence of long-term IS. In additional, in patients with symptomatic CAS, clinical trials have demonstrated that carotid endarterectomy (CEA) is superior to medical therapy for prevention of future CAS-related IS. However, CEA is not suitable for CAS post-radiotherapy or those located at higher level of the internal carotid artery; and major complications of this procedure including cranial nerve injuries have stimulated the interest of using percutaneous transfemoral carotid stenting as an alternative approach. Although transfemoral arterial approach of carotid stenting is not inferior to CEA in improving clinical outcomes, it has been reported to be associated with vascular complication and has its limitations in patients with athero-occlusive disease of abdominal aorta or bilateral iliac arteries, level II or III aortic arch, or bovine type carotid arterial anatomy. Therefore, transradial/transbrachial arterial approach has emerged as a novel method for carotid stenting. This article provides a critical review on interventional approaches for the treatment of CAS. PMID:27061654

  2. Carotid Stent Fracture from Stylocarotid Syndrome

    Science.gov (United States)

    Hooker, Jeffrey D; Joyner, David A; Farley, Edward P; Khan, Majid

    2016-01-01

    Eagle syndrome is a rare condition resulting from elongation of the temporal styloid process or calcification of its associated stylohyoid ligaments. Although usually presenting with pain or odynophagia, Eagle syndrome has been reported to cause a multitude of neurologic symptoms or vascular complications, some of which can be life-threatening. We present a case in which an endovascularly placed internal carotid artery stent in close proximity to a calcified stylohyoid ligament resulted in stent fracture with subsequent stent and vessel occlusion. We review and discuss the presentation, diagnosis, etiology, complications and treatment options of the syndrome.

  3. Stent, drug, polymer——enefits, risks, and opportunities

    Institute of Scientific and Technical Information of China (English)

    Samuel J. Shubrooks

    2006-01-01

    @@ It has been well established that use of drug-eluting stents has resulted in marked reduction in neointimal proliferation following stenting and that this is reflected clinically in a very significant decrease in late lumen loss, instent restenosis, and target lesion revascularization. This benefit occurs, however, in the setting of delayed endothelial and vascular wall healing with its potential for continuing thrombogenicity requiring more prolonged use of dual antiplatelet therapy to prevent stent thrombosis.

  4. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... of the bare metal stent versus the drug-coated stents is an ongoing debate. And I think ... that with putting in a bunch of drug-coated stents, and it looks very pretty when we’ ...

  5. Subacute stent thrombosis and the anticoagulation controversy: changes in drug therapy, operator technique, and the impact of intravascular ultrasound.

    Science.gov (United States)

    Moussa, I; Di Mario, C; Di Francesco, L; Reimers, B; Blengino, S; Colombo, A

    1996-08-14

    Clinical trials have shown that stents are superior to other catheter-based coronary interventions in terms of reduced complications and improved long-term efficacy. With utilization of high-pressure balloon inflation and intravascular ultrasound (IVUS) guidance, stent implantation can now be performed safely without anticoagulation (i.e., with lower rates of stent thrombosis and vascular complications). In 2 recent prospective clinical trials, stent thrombosis occurred in 3.5% of cases despite anticoagulant therapy, which resulted in an average of 7% vascular and bleeding complications. Initial use of IVUS during traditional stent deployment showed that 80% of stents were underexpanded and led to the hypothesis that stent thrombosis might be decreased as a result of optimal stent placement under IVUS guidance without the need for anticoagulation. In a prospective clinical trial to test this hypothesis, three factors were found to reduce stent thrombosis: full stent expansion, complete apposition to the vessel wall, and full lesion coverage. Predictors of thrombotic risk in this era of high-pressure stent deployment without anticoagulation include low ejection fraction, residual dissections, slow flow, multiple stents per lesion, and smaller postprocedure stent luminal diameter. To optimize stent expansion, stent dilation should be performed using a mean inflation pressure of 18 atm with a noncompliant or minimally compliant balloon sized to the vessel being treated (B/V ratio = 1.1). Controversy still remains about the best poststent antiplatelet regimen, and results of a recent trial should indicate whether heparin coating provides additional protection from stent thrombosis.

  6. Innovations in Stroke Prevention: An Update on Carotid Stenting

    Medline Plus

    Full Text Available ... risk of stroke in the high-risk patient population. The most common complication was a neck hematoma ... safer than carotid stenting, at least in this population of patients. And the risk of cerebral vascular -- ...

  7. Longitudinal stent deformation during coronary bifurcation stenting.

    Science.gov (United States)

    Vijayvergiya, Rajesh; Sharma, Prafull; Gupta, Ankush; Goyal, Praveg; Panda, Prashant

    2016-03-01

    A distortion of implanted coronary stent along its longitudinal axis during coronary intervention is known as longitudinal stent deformation (LSD). LSD is frequently seen with newer drug eluting stents (DES), specifically with PROMUS Element stent. It is usually caused by impact of guide catheter tip, or following passage of catheters like balloon catheter, IVUS catheter, guideliner, etc. We hereby report a case of LSD during coronary bifurcation lesion intervention, using two-stents technique. Patient had acute stent thrombosis as a complication of LSD, which was successfully managed. PMID:26811144

  8. Symptomatic stent cast.

    LENUS (Irish Health Repository)

    Keohane, John

    2012-02-03

    Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

  9. Symptomatic stent cast.

    Science.gov (United States)

    Keohane, John; Moore, Michael; O'Mahony, Seamus; Crosbie, Orla

    2008-02-01

    Biliary stent occlusion is a major complication of endoscopic stent insertion and results in repeat procedures. Various theories as to the etiology have been proposed, the most frequently studied is the attachment of gram negative bacteria within the stent. Several studies have shown prolongation of stent patency with antibiotic prophylaxis. We report the case of stent occlusion from a cast of a previously inserted straight biliary stent; a "stent cast" in an 86-year-old woman with obstructive jaundice. This was retrieved with the lithotrypter and she made an uneventful recovery. This is the first reported case of a biliary stent cast.

  10. Next generation coronary CT angiography: in vitro evaluation of 27 coronary stents

    Energy Technology Data Exchange (ETDEWEB)

    Gassenmaier, Tobias; Bley, Thorsten A. [University Hospital Wuerzburg, Department of Diagnostic and Interventional Radiology, Wuerzburg (Germany); Petri, Nils; Voelker, Wolfram [University Hospital Wuerzburg, Department of Internal Medicine I, Wuerzburg (Germany); Allmendinger, Thomas; Flohr, Thomas [Siemens Healthcare, Forchheim (Germany); Maintz, David [University of Cologne, Department of Radiology, Cologne (Germany)

    2014-11-15

    To evaluate in-stent lumen visibility of 27 modern and commonly used coronary stents (16 individual stent types, two stents at six different sizes each) utilising a third-generation dual-source CT system. Stents were implanted in a plastic tube filled with contrast. Examinations were performed parallel to the system's z-axis for all stents (i.e. 0 ) and in an orientation of 90 for stents with a diameter of 3.0 mm. Two stents were evaluated in different diameters (2.25 to 4.0 mm). Examinations were acquired with a collimation of 96 x 0.6 mm, tube voltage of 120 kVp with 340 mAs tube current. Evaluation was performed using a medium-soft (Bv40), a medium-sharp (Bv49) and a sharp (Bv59) convolution kernel optimised for vascular imaging. Mean visible stent lumen of stents with 3.0 mm diameter ranged from 53.3 % (IQR 48.9 - 56.7 %) to 73.9 % (66.7 - 76.7 %), depending on the kernel used at 0 , and was highest at an orientation of 90 with 80.0 % (75.6 - 82.8 %) using the Bv59 kernel, strength 4. Visible stent lumen declined with decreasing stent size. Use of third-generation dual-source CT enables stent lumen visibility of up to 80 % in metal stents and 100 % in bioresorbable stents. (orig.)

  11. Forming of magnesium alloy microtubes in the fabrication of biodegradable stents

    NARCIS (Netherlands)

    Wang, L.; Fang, G.; Qian, L.; Leeflang, M.A.; Duszczyk, J.; Zhou, J.

    2014-01-01

    Magnesium alloys have, in recent years, been recognized as highly promising biodegradable materials, especially for vascular stent applications. Forming of magnesium alloys into high-precision thin-wall tubes has however presented a technological barrier in the fabrication of vascular stents, becaus

  12. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... put in, versus medicated or what’s known as drug-eluding stents. And there has been a lot ... Both bare metal stents and medicated stents, or drug-eluting stents, have their role, and we often ...

  13. Simulation of stent deployment in a realistic human coronary artery

    Directory of Open Access Journals (Sweden)

    van der Steen Anton FW

    2008-08-01

    Full Text Available Abstract Background The process of restenosis after a stenting procedure is related to local biomechanical environment. Arterial wall stresses caused by the interaction of the stent with the vascular wall and possibly stress induced stent strut fracture are two important parameters. The knowledge of these parameters after stent deployment in a patient derived 3D reconstruction of a diseased coronary artery might give insights in the understanding of the process of restenosis. Methods 3D reconstruction of a mildly stenosed coronary artery was carried out based on a combination of biplane angiography and intravascular ultrasound. Finite element method computations were performed to simulate the deployment of a stent inside the reconstructed coronary artery model at inflation pressure of 1.0 MPa. Strut thickness of the stent was varied to investigate stresses in the stent and the vessel wall. Results Deformed configurations, pressure-lumen area relationship and stress distribution in the arterial wall and stent struts were studied. The simulations show how the stent pushes the arterial wall towards the outside allowing the expansion of the occluded artery. Higher stresses in the arterial wall are present behind the stent struts and in regions where the arterial wall was thin. Values of 200 MPa for the peak stresses in the stent strut were detected near the connecting parts between the stent struts, and they were only just below the fatigue stress. Decreasing strut thickness might reduce arterial damage without increasing stresses in the struts significantly. Conclusion The method presented in this paper can be used to predict stresses in the stent struts and the vessel wall, and thus evaluate whether a specific stent design is optimal for a specific patient.

  14. Optical coherence tomography to evaluate coronary stent implantation and complications.

    Science.gov (United States)

    Hayat, Umair; Thondapu, Vikas; Ul Haq, Muhammad Asrar; Foin, Nicolas; Jang, Ik-Kyung; Barlis, Peter

    2015-08-01

    Coronary optical coherence tomography (OCT) is now an established imaging technique in many catheterization laboratories worldwide. With its near-histological view of the vessel wall and lumen interface, it offers unprecedented imaging quality to improve our understanding of the pathophysiology of atherosclerosis, plaque vulnerability, and vascular biology. Not only is OCT used to accurately detect atherosclerotic plaque and optimize stent position, but it can further characterize plaque composition, quantify stent apposition, and assess stent tissue coverage. Given that its resolution of 15 μm is well above that of angiography and intravascular ultrasound, OCT has become the invasive imaging method of choice to examine the interaction between stents and the vessel wall. This review focuses on the application of OCT to examine coronary stents, the mechanisms of stent complications, and future directions of OCT-guided intervention. PMID:26247272

  15. The Supralimus sirolimus-eluting stent.

    Science.gov (United States)

    Lemos, Pedro A; Bienert, Igor

    2013-05-01

    The use of biodegradable polymeric coatings has emerged as a potential bioengineering target to improve the vascular compatibility of coronary drug-eluting stents (DESs). This review summarizes the main features and scientific facts about the Supralimus sirolimus-eluting stent (Sahajanand Medical Technologies Ltd, Surat, India), which is a biodegradable polymer-based, sirolimus-eluting metallic stent that was recently introduced for routine use in Europe. The novel stent is built on a stainless steel platform, coated with a blend of biodegradable polymers (poly-l-lactide, poly-dl-lactide-co-glycolide and polyvinyl pyrrolidone; coating thickness is 4-5 µm). The active agent is the antiproliferative sirolimus in a dose load of 1.4 µg/mm(2), which is released within 48 days. The Supralimus stent was initially evaluated in the single-arm SERIES-I study, which showed binary angiographic restenosis rates of 0% (in-stent) and 1.7% (in-segment) and an in-stent late lumen loss of 0.09 ± 0.28 mm. The multicenter randomized PAINT trial compared two DESs with identical metallic platforms and biodegradable polymer carriers, but different agents (Infinnium [Sahajanand Medical Technologies Pvt Ltd] paclitaxel-eluting stent or Supralimus sirolimus-eluting stent) against bare stents. After 3 years, the pooled DES population had similar rates of cardiac death or myocardial infarction (9 vs 7.1%; p = 0.6), but a lower risk of repeat interventions (10 vs 29.9%; p < 0.01) than controls with bare stents. The incidence of definite or probable stent thrombosis in the pooled DES group was 2.3% (1st year: 1.8%; 2nd year: 0.4% and 3rd year: 0%). These results demonstrate that the novel Supralimus stents are effective in reducing reintervention, while potentially improving the safety profile by decreasing the risk of late-term thrombosis, even though further studies would be necessary to confirm these findings.

  16. Stimulation of vascular cells by extracellular signals - A biophysical analysis

    OpenAIRE

    Biela, Sarah A.

    2009-01-01

    Stimulation of vascular cells by extracellullar signals Treatment of vascular diseases often requires the selective addressing of endothelial (ECs) and smooth muscle cells (SMCs). The two vascular cell types are important for the wound healing after stent implantation. Recent research designs new materials and coatings for stents to improve the complex healing process. The aim of my work was to find and investigate different reactions in the two vascular cell types (ECs and SMCs) through surf...

  17. Characteristic mechanical properties of balloon-expandable peripheral stent systems

    International Nuclear Information System (INIS)

    Purpose: To measure in vitro geometric-mechanical characteristics of balloon-expandable peripheral stent systems for determining suitability for specific vascular regions. Materials and Methods: Balloon-expandable stents including their delivery systems manufactured by Guidant (OTW MegalinkTM), Inflow Dynamics (Antares), Medtronic (AVE BridgeTM), Biotronik (PeironTM) and Cordis (Corinthian IQTM) were selected for this study. When expanded, all stents had a nominal diameter of 8 mm. The length was 38-40 mm. Stent profile, trackability, length change on expansion, stiffness, elastic recoil, and radio-opacity in the crimped and expanded state of these stent systems were determined with specially developed test methods. Results: The Corinthian IQTM, MegalinkTM and PeironTM required the smallest force to pass through the vascular model. While the BridgeTM system had the largest profile with a diameter of 2.430 mm, all other stent systems had a significantly smaller diameter ranging from 1.970 mm for the PeironTM to 2.078 mm for the Corinthian IQTM. In the distal region of the stent delivery system, the MegalinkTM was the most flexible and the BridgeTM system the stiffest. Elastic recoil for all stents was in the range of 2.5% to 3.5%, with the exception of the BridgeTM stent, which had an elastic recoil of 4.79%. The Corinthian IQTM stent had noticeably the highest radial stiffness. In the expanded condition, the PeironTM was the most flexible while the Corinthian IQTM and AntaresTM were found to be the stiffest. Length change (shrinkage on expansion) ranged from 0.54 to 6.57%, with the exception of the Corinthian IQ, which shrunk >7 mm (18.5%) on expansion. All stent systems in the crimped and expanded state were readily visible radiographically. (orig.)

  18. A Nano-Inspired Multifunctional POSS-PCU Covered Stent: Endothelial Progenitor Cell Capture with Stealth Liposomal Drug Release

    OpenAIRE

    Tan, A. J. K.

    2014-01-01

    The 2 main unresolved issues inherent in coronary stents are in-stent restenosis (ISR) and late stent thrombosis (ST). ISR is largely due to vascular smooth muscle cell (VSMC) proliferation, and ST is attributed to a lack of re-endothelialization. This thesis describes the conceptualization and development of a biofunctionalized polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) platform, for the express purpose of circumventing ISR and ST. A bare-metal stent is emb...

  19. A review on biodegradable materials for cardiovascular stent application

    Science.gov (United States)

    Hou, Li-Da; Li, Zhen; Pan, Yu; Sabir, MuhammadIqbal; Zheng, Yu-Feng; Li, Li

    2016-09-01

    A stent is a medical device designed to serve as a temporary or permanent internal scaffold to maintain or increase the lumen of a body conduit. The researchers and engineers diverted to investigate biodegradable materials due to the limitation of metallic materials in stent application such as stent restenosis which requires prolonged anti platelet therapy, often result in smaller lumen after implantation and obstruct re-stenting treatments. Biomedical implants with temporary function for the vascular intervention are extensively studied in recent years. The rationale for biodegradable stent is to provide the support for the vessel in predicted period of time and then degrading into biocompatible constituent. The degradation of stent makes the re-stenting possible after several months and also ameliorates the vessel wall quality. The present article focuses on the biodegradable materials for the cardiovascular stent. The objective of this review is to describe the possible biodegradable materials for stent and their properties such as design criteria, degradation behavior, drawbacks and advantages with their recent clinical and preclinical trials.

  20. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... target lesion. Now with the stents being as flexible as they are, we can pretty much get to anywhere we want. The issue of the bare metal stent versus the drug-coated stents is an ongoing debate. ...

  1. Endovascular stent grafting: a review

    Energy Technology Data Exchange (ETDEWEB)

    Kribs, S. [Univ. of Western Ontario, Dept. of Vascular and Interventional Radiology, London, Ontario (Canada)

    2001-06-01

    Endovascular stent grafts are intravascular devices composed of surgical graft material and a metallic frame, (Fig. 1). Their main application has been to treat aneurysms, but they have been used in vascular trauma and are being investigated for use in occlusive disease. Their advantage in treating aneurysms over conventional surgical treatment is that they are loaded into relatively small delivery systems (Fig. 2) and can be introduced to the area of interest from a remote site - usually the femoral artery. This avoids the morbidity of surgical exposure in difficult sites, such as the thoracic aorta, and lessens the cardiovascular stress to patients by eliminating the need to surgically cross-clamp the vessel being treated. The first description of abdominal aortic aneurysm exclusion by an endovascular stent graft was provided by Parodi and colleagues in 1991. Much of the early clinical experience in endovascular stent grafting was obtained from centres in Australia and Europe, and they are now reporting midterm follow-up data. There are now many centres in Canada and the United States involved in endovascular research and practice. (author)

  2. Biocompatibility of coronary stent materials: effect of electrochemical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Scheerder, I. de [University Hospital Leuven (Belgium). Dept. of Cardiology; Sohier, J.; Froyen, L.; Humbeeck, J. van [Louvain Univ. (Belgium). Dept. of Metallurgy and Materials Engineering; Verbeken, E. [University Hospital Leuven (Belgium). Dept. of Pathology

    2001-02-01

    Percutaneous Transluminal Coronary Revascularization (PTCR) is now a widely accepted treatment modality for atherosclerotic coronary artery disease. Current multicenter randomized trials comparing PTCR with the more invasive Coronary Artery Bypass Grafting could not show long-term significant survival differences. During the last two decades progress has been made to further optimize PTCR. The most logic approach to treat atherosclerotic coronary narrowings is to remove the atherosclerotic material using especially developed devices. Several trials, however, could not show a significant beneficial outcome after use of these devices compared to plain old balloon angioplasty. Another approach was to implant a coronary prothesis (stent), scaffolding the diseased coronary artery after PTCA. This approach resulted in a decreased restenosis rate at follow-up. The beneficial effects of stenting, however, was not found to be related to the inhibition of the neointimal cellular proliferation after vascular injury, but simply to be the mechanical result of overstretching of the treated vessel segment. The most important remaining clinical problem after stenting remains the neointimal hyperplasia within the stent, resulting in a significant stent narrowing in 13 to 30% of patients. Further efforts to improve the clinical results of coronary stenting should focus on the reduction of this neointimal hyperplasia. Neointimal hyperplasia after stent implantation results from (1) a healting response to the injury caused by the stent implantation and (2) a foreign body response to the stent itself. Factors that seem to influence the neointimal hyperplastic response are genetic, local disease related, stent delivery related and stent related factors. Biocompatibilisation of coronary stents by looking for more biocompatible metal alloys, optimized surface characteristics and optimized stent designs should result in a better late patency. Furthermore drug eluting and radioactive stents

  3. Stent-graft and multilayer stent for treatment of type II thoracoabdominal aortic aneurysm in a high-risk patient.

    Science.gov (United States)

    Pane, B; Spinella, G; Salcuni, M; Palombo, D

    2013-08-01

    The aim of the present article was to present an alternative endovascular treatment for type II thoracoabdominal aortic aneurysm that would have the advantage of limiting the duration of the procedure and the use of contrast. A high-risk patient was admitted to our Vascular Unit for type II thoracoabdominal aneurysm according to Crawford's classification. Two thoracic stent-grafts (Valiant Captivia, Medtronic, Pewaukee, WI, USA), a bifurcated stent-graft (Endurant Medtronic) and two multilayer stents (Cardiatis SA, Isnes, Belgium) were deployed. No postoperative major complications were observed. Operative time and use of contrast material were 45 min and 80 mL, respectively. Computed angiography tomography at 1 and 6 months showed patency of visceral and renal arteries and progressive thrombosis of the aneurysmal sac. This stent-graft treatment in combination with multilayer stent could be an alternative treatment for thoracoabdominal aneurysm in high-risk patients. PMID:24013540

  4. Neoatherosclerosis in the stent

    Directory of Open Access Journals (Sweden)

    A. A. Komkov

    2015-01-01

    Full Text Available Achievements of interventional cardiology in the treatment of coronary artery disease are based on coronary balloon angioplasty with implanting bare metal stents and drug eluting stents. Questions of complications such as early stent thrombosis and restenosis of stent were solved in a considerable degree. However, with the lengthening of the followup period, the problem of late complications became obvious. Except endothelization and fibromuscular proliferation in stented coronary arteries the process of plaque formation has an important influence on later complications in follow-up period more than one year. This process was defined as neoatherosclerosis. This is verified by clinical manifestations of the disease, histological studies, angioscopy, intravascular ultrasound and optical-coherence tomography in stented patients. Dynamic observation of the condition in stentedcoronary arteries showed multistep proliferation with restenosis, its regression, and neoatherosclerosis development. Evidences of neoatherosclerosis formation in stented coronary arteries are considered in this review.

  5. Combined use of transmyocardial stents with gene therapy in the treatment of acute myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    王永武

    2006-01-01

    Objective To determine the efficacy of combined use of transmyocardial stent with gene therapy to treat acute myocardial infarction in porcine model. Methods 24 Chinese mini swines have been devided into 4 groups randomly: group myocardial infarction (group MI n1 = 6), group transmyocardial stent (group ST n2 = 6) , group vascular endothelial growth factor (group VEGF n3 = 6) , group transmyocardial stent and VEGF (group ST + VEGF n4 = 6). In group MI,acute myocardial infarc-

  6. Unusual Response of Subclavian In-Stent Restenosis to Balloon Angioplasty in a Patient with HIV

    Directory of Open Access Journals (Sweden)

    Mohammad Atif Rana

    2015-01-01

    Full Text Available Human Immunodeficiency Virus (HIV infection and use of protease inhibitors have been associated with accelerated atherosclerosis. Increased rates of coronary in-stent restenosis are reported in these patients. There is limited data available on peripheral vascular disease interventions on these patients. Herein we report an aggressive subclavian in-stent restenosis with an unexpected response to balloon angioplasty treatment with a large, mobile tissue flap formation and its treatment with another stent.

  7. RX Herculink Elite® renal stent system: a review of its use for the treatment of renal artery stenosis

    Directory of Open Access Journals (Sweden)

    Colyer Jr

    2012-08-01

    Full Text Available William R Colyer JrDivision of Cardiovascular Medicine, University of Toledo Medical Center, Toledo, OH, USAAbstract: The management of renal artery stenosis (RAS remains controversial. While some evidence suggests that treatment with stent placement is beneficial, randomized trials have failed to demonstrate a significant benefit. Ongoing clinical trials should help to better define the role for stenting of RAS while avoiding limitations seen with earlier trials. When it comes to stenting for RAS, several stents have been used; however, many stents which have been used previously and which are still being used are biliary stents that are used “off-label.” These stents have typically come onto the market through the 510(k pathway. To date, a total of five stents have been approved by the United States Food and Drug Administration for use in the renal arteries. Of the five stents that have received approval, the Bridge™ Extra Support (Medtronic CardioVascular, Santa Rosa, CA and the Palmaz® (Cordis Corporation, Bridgewater, NJ stents are no longer available. Currently, the Express® SD (Boston Scientific, Natick, MA, Formula™ (Cook Medical, Bloomington, IN, and Herculink Elite® (Abbott Vascular, Santa Clara, CA stents are Food and Drug Administration approved and available for use. The Herculink Elite is the most recently approved of the renal stents, having received approval in late 2011. The Herculink Elite stent is the only cobalt chromium stent approved for use in the renal arteries. Although trial data are limited and direct comparisons among renal stents is not possible, the Herculink Elite stent has demonstrated good performance. Additionally, the design of the Herculink Elite offers some advantages that may translate into improved outcomes.Keywords: renal artery stenosis, stenting, FDA approval

  8. Adhesion of monocytes to medical steel as used for vascular stents is mediated by the integrin receptor Mac-1 (CD11b/CD18; alphaM beta2) and can be inhibited by semiconductor coating.

    Science.gov (United States)

    Schuler, Pia; Assefa, Dawit; Ylänne, Jari; Basler, Nicole; Olschewski, Manfred; Ahrens, Ingo; Nordt, Thomas; Bode, Christoph; Peter, Karlheinz

    2003-01-01

    Implantation of stents into stenosed arteries helps to restore normal blood flow in ischemic organs. However, limited biocompatibility of the applied medical steel can cause acute thrombosis and long-term restenosis. Adhesion of monocytes to stent metal may participate in those acute and long-term complications of stent placement. Based on described prominent electrochemical properties of the interaction between the monocyte integrin receptor Mac-1 and its various ligands, we hypothesized, that this receptor is a central mediator of monocyte adhesion to stent metal and that semiconductor coating of medical steel reduces monocyte adhesion. Adhesion of monocytes on L-316 stainless steel was directly evaluated by light microscopy. Mac-1 could be identified as mediator of monocyte adhesion, since cell adhesion could be blocked by anti-Mac-1-antibodies, including the cross-reacting anti-GPIIb/IIIa antibody fragment abciximab. To further prove the central role of Mac-1, two CHO cell lines were generated expressing recombinant Mac-1 either as wild type, resulting in a low affinity receptor, or mutant with a GFFKR deletion of the alpha(M) subunit, resulting in a high affinity receptor. Indeed, adhesion was specific for Mac-1 and dependent on the affinity state of this integrin. Finally, we could demonstrate that Mac-1-mediated adhesion of monocytes to stents can be significantly inhibited by silicon carbide coating of the stent metal. In conclusion, the integrin Mac-1 and its affinity state could be identified as major mediators of monocyte adhesion on medical steel. As therapeutic strategies, the blockade of Mac-1 by antibodies or silicon carbide coating of steel inhibits monocyte adhesion on stents. PMID:12881037

  9. Forming of magnesium alloy microtubes in the fabrication of biodegradable stents

    OpenAIRE

    Wang, L; Fang, G.; Qian, L.; Leeflang, M. A.; Duszczyk, J.; Zhou, J.

    2014-01-01

    Magnesium alloys have, in recent years, been recognized as highly promising biodegradable materials, especially for vascular stent applications. Forming of magnesium alloys into high-precision thin-wall tubes has however presented a technological barrier in the fabrication of vascular stents, because of the poor workability of magnesium at room temperature. In the present study, the forming processes, i.e., hot indirect extrusion and multi-pass cold drawing were used to fabricate seamless mic...

  10. Smooth muscle-specific drug targets for next generation Drug-eluting stent

    OpenAIRE

    Tang, Rui; Chen, Shiyou

    2013-01-01

    The occurrence of stent thrombosis is one of the major obstacles limiting the long-term clinical efficacy of percutaneous coronary intervention. The anti-smooth muscle proliferation drugs coated on drug-eluting stents (DES) often indistinguishably block re-endothelialization, an essential step toward successful vascular repair, due to their non-specific effect on endothelial cells (EC). Therefore, identification of therapeutic targets that differentially regulate vascular smooth muscle cell (...

  11. Using COMSOL Multiphysics for Biomechanical Analysis of Stent Technology in Cerebral Aneurysms

    DEFF Research Database (Denmark)

    Rasmussen, Joachim; Thyregod, Jesper; Enevoldsen, Marie Sand;

    2009-01-01

    This work presents new fluid-structure interaction (FSI) models in both 2D and 3D of the effect of using vascular stents as treatment of cerebral berry aneurysms. The stent is positioned inside the cerebral artery covering the neck of the aneurysm. The stent is expected to alter the blood flow in...... and strut size, shape, and position are modeled in 2D and 3D FSI models. The models show that pore size and strut shape both have significant influence on stent efficiency....

  12. Correlation of platelet activation and inflammatory factor to vascular restenosis following intravascular stent implantation%脑血管支架置入者血小板活化和炎性因子与血管再狭窄的关联

    Institute of Scientific and Technical Information of China (English)

    王红艳; 张迎泉

    2009-01-01

    OBJECTIVE: To explore the correlation among platelet activation, inflammatory factor changes and vascular restenosis following intravascular stent implantation.METHODS: Chinese Journal Full-Text Database and Pubmed were retrieved using search terms of intracranial arterial, stents,stenosis, elevated platelet activation, and inflammatory factors from January 1999 to June 2009. The language was restricted within Chinese and English. Simultaneously, platelet activation and inflammatory factor changes were acted as evaluation indexes. Accordingly, clinical research regarding treating intracranial artery stenosis with intravascular stent implantation was included. The animal experiment or other treatment methods were excluded.RESULTS: A total of 650 papers were obtained by initial search with computer. According to inclusion criteria, the related papers were analyzed. Platelet activation, inflammatory reaction and inflammatory factor were the focuses of research concerning restenosis following intravascular stent implantation. Platelet thrombus was the main factor to cause acute vascular occlusion, and the activated platelet aggravated the damage of endothelial cells, which induced over proliferation of smooth muscle cell. As a kind of foreign body, the stent implantation was closely associated with complication, such as formation of thrombosis, acute vascular occlusion, vasovagal reflex and immune reaction, which lead to reconstruction of vessel wall and in-stent restenosis.CONCLUSION: It is effective to cure vascular restenosis by undergoing antiplatelet therapy prior to implantation, controlling inflammatory reaction, as well as inhibiting vascular smooth muscle cell proliferation following intravascular stent implantation.%目的:探讨脑血管支架置入后血小板活化和炎性因子的变化与再狭窄的关系.方法:以颅内动脉,支架,狭窄,血小板活化,炎症因子为检索词,检索中国期刊全文数据库(1999-01/2009-06);以intracranial

  13. Late pseudocoarctation syndrome after stent-graft implantation for traumatic aortic rupture.

    Science.gov (United States)

    Letocart, Vincent; Fau, Georges; Tirouvanziam, Ashok; Toquet, Claire; Al Habash, Oussama; Guerin, Patrice; Rousseau, Hervé; Crochet, Dominique

    2013-06-01

    The present observation illustrates an unusual complication occurring after stent-grafting (S-graft) for aortic isthmus rupture. A 22-year-old patient, treated by S-graft in the emergency department for traumatic aortic rupture, was readmitted 10 months later with pseudocoarctation syndrome. A membrane was found inside the stent-graft that had induced a pseudo-dissection, which caused the pseudocoarctation syndrome. Surgical treatment consisted of removing the stent-graft and membrane and replacing it with a vascular implant. The patient's clinical course was fair. The suggested mechanism was circumferential neoendothelialization of the stent-graft. Dehiscence caused the superior part of the membrane to drop into the lumen of the stent-graft creating a "false channel" that compressed the "true lumen" and induced "pseudocoarctation" syndrome. The cause of the extensive neointimalization remains unexplained. Thoracic aortic stent-grafts require regular follow-up monitoring by angioscan or angio-magnetic resonance imaging.

  14. 生物可降解材料聚乳酸/聚羟基乙酸复合壳聚糖在人工冠状动脉血管支架制备中的应用%Artificial Coronary Vascular Stents Fabrication Using Biodegradable Material Compounds of PLA/PGA-co-Chitosan

    Institute of Scientific and Technical Information of China (English)

    郭清奎

    2012-01-01

    The first generation scaffolds of bare metal stents (BMS) and the second generation of drug eluting stents (DES) have been widely used in the treatment of coronary heart diseases. However, long term incidences of major adverse cardiovascular events and revascularization treatments are still high because of in-stent re-stenosis and thrombosis. These may be caused by chronic inflammations and vascular wall damages due to persistent metal stents stimulation. What's more, the eluting drugs within metal stents could also disturb normal growth of vascular endothelial cell, intima, tunica media, smooth muscle and epimysium. Therefore, in order to meet these demands several fully biodegradable scaffolds and drug carried stents have been manufactured using polymers polyester, polycarbonate and polyphosphate, etc. Among them, the security and histo-and hemo-compatibilities of coronary scaffolds made from poly-lactic acid (PLA), poly-glycolic acid (PGA), chitosan as coating, poly-caprolactone (PCL) and other copolymer like poly-lactic-co-glycolic acid (PLGA) have been testified to be sound. Nevertheless, there exist several different shortages for these stents such as tensile strength deficiency and slow degradation. PLA is hard and brittle with slow degradation, while PGA is soft with insufficient support force and fast degradation. Whether stents degrade too fast or too slow, they could not supply sufficient strength and effective support after implantation, and also they may cause target vascular injuries and elastic shrink inducing restenosis and thrombosis in long terms. Using optimized molar ratio component of PLA and PGA with chitosan coating, we can get sound composite materials with better biocompatibility, moderate degradation (approximately 3 - 6 months of complete degradation), adequate mechanical strength, lower inflammatory response and good range of extension, and establish an experiment ground for fully biodegradable vascular scaffolds fabrication.%第一代

  15. An Update to Hepatobiliary Stents

    OpenAIRE

    Moy, Brian T.; Birk, John W.

    2015-01-01

    Endoscopic stent placement is a common primary management therapy for benign and malignant biliary strictures. However, continuous use of stents is limited by occlusion and migration. Stent technology has evolved significantly over the past two decades to reduce these problems. The purpose of this article is to review current guidelines in managing malignant and benign biliary obstructions, current endoscopic techniques for stent placement, and emerging stent technology. What began as a simpl...

  16. Intravascular ultrasound assessed incomplete stent apposition and stent fracture in stent thrombosis after bare metal versus drug-eluting stent treatment the Nordic Intravascular Ultrasound Study (NIVUS)

    DEFF Research Database (Denmark)

    Kosonen, Petteri; Vikman, Saila; Jensen, Lisette Okkels;

    2013-01-01

    This prospective multicenter registry used intravascular ultrasound (IVUS) in patients with definite stent thrombosis (ST) to compare rates of incomplete stent apposition (ISA), stent fracture and stent expansion in patients treated with drug-eluting (DES) versus bare metal (BMS) stents. ST...... is a rare, but potential life threatening event after coronary stent implantation. The etiology seems to be multifactorial....

  17. Direct stenting versus direct stenting followed by centered beta-radiation with intravascular ultrasound-guided dosimetry and long-term anti-platelet treatment: results of a randomized trial: Beta-Radiation Investigation with Direct Stenting and Galileo in Europe (BRIDGE).

    NARCIS (Netherlands)

    P.W.J.C. Serruys (Patrick); W. Wijns (William); G. Sianos (Georgios); I.K. de Scheerder (Ivan); P.A. van den Heuvel (Paul); W.R. Rutsch (Wolfgang); H.D. Glogar (Helmut); C.M. Miguel (Carlos); P.H. Materne (Phillipe); S. Veldhof (Susan); H. Vonhausen (Heike); P.C. Otto-Terlouw (Patricia); W.J. van der Giessen (Wim)

    2004-01-01

    textabstractAbstract OBJECTIVES: We sought to assess the efficacy of vascular brachytherapy (VBT) combined with stenting for the primary prevention of restenosis. BACKGROUND: Intravascular brachytherapy after stent implantation for de novo lesions has been abandoned for the present. We revisited t

  18. An automatic algorithm for detecting stent endothelialization from volumetric optical coherence tomography datasets

    Science.gov (United States)

    Bonnema, Garret T.; O'Halloran Cardinal, Kristen; Williams, Stuart K.; Barton, Jennifer K.

    2008-06-01

    Recent research has suggested that endothelialization of vascular stents is crucial to reducing the risk of late stent thrombosis. With a resolution of approximately 10 µm, optical coherence tomography (OCT) may be an appropriate imaging modality for visualizing the vascular response to a stent and measuring the percentage of struts covered with an anti-thrombogenic cellular lining. We developed an image analysis program to locate covered and uncovered stent struts in OCT images of tissue-engineered blood vessels. The struts were found by exploiting the highly reflective and shadowing characteristics of the metallic stent material. Coverage was evaluated by comparing the luminal surface with the depth of the strut reflection. Strut coverage calculations were compared to manual assessment of OCT images and epi-fluorescence analysis of the stented grafts. Based on the manual assessment, the strut identification algorithm operated with a sensitivity of 93% and a specificity of 99%. The strut coverage algorithm was 81% sensitive and 96% specific. The present study indicates that the program can automatically determine percent cellular coverage from volumetric OCT datasets of blood vessel mimics. The program could potentially be extended to assessments of stent endothelialization in native stented arteries.

  19. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... But there is clearly a huge body of data that shows that tobacco use is associated with ... medicated stents. I hear they’re bad.” The data that has come out since then has showed ...

  20. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... not to just ignore any kind of symptoms. Diabetics, in particular, are a subclass of patients who ... vessel disease or multiple vessel blockages, or a diabetic, we think that the drug-eluting stents are ...

  1. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... the equipment that we use from the early days has undergone a sea change. The catheters that ... the stent design has improved from the early days when they were very difficult to deploy and ...

  2. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... care of the intravenous medications and any other medicines that need to be administered in monitoring his ... put in, versus medicated or what’s known as drug-eluding stents. And there has been a lot ...

  3. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... have accessed the femoral artery, which is the big blood vessel in the leg, through which we ... getting to the point where if it’s a big artery, a bare metal stent will work, a ...

  4. Coronary Angioplasty Stent Placement

    Science.gov (United States)

    ... 2009 Welcome to this OR-Live westbound cast presentation, live from Shawnee Mission Medical Center in Merriam, ... putting in a bare metal stent. The whole theory behind that is you have a lesser chance ...

  5. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... 2009 Welcome to this OR-Live westbound cast presentation, live from Shawnee Mission Medical Center in Merriam, ... putting in a bare metal stent. The whole theory behind that is you have a lesser chance ...

  6. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... the opening of the blood vessel. It’s a collagen plug, and that will help seal the opening. ... stent should be on Plavix or a similar type of anti-platelet drug lifelong. One of the ...

  7. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... a big artery, a bare metal stent will work, a smaller artery or in some of the ... the equipment that we use from the early days has undergone a sea change. The catheters that ...

  8. Treatment of carotid artery aneurysms with covered stents; Aneurysmabehandlung der Arteria carotis interna mit gecoverten Stents

    Energy Technology Data Exchange (ETDEWEB)

    Rohr, A.; Alfke, K.; Doerner, L.; Jansen, O. [UKSH Kiel (Germany). Neurochirurgie Neuroradiologie; Bartsch, T.; Stingele, R. [UKSH Kiel (Germany). Neurologie

    2007-10-15

    Purpose: Evaluation of the use of covered stents in treating pseudoaneurysms of the cervical and intracranial/extradural carotid artery and determination of the periprocedural and short- to mid-term complication rate. Materials and Methods: 8 patients with 9 spontaneous dissecting aneurysms of the cervical carotid artery - 5 of which were symptomatic - plus one patient with ofthalmoplegia due to an aneurysm of the cavernous carotid artery were studied. While the latter was treated with a PTFE-covered balloon-mounted stainless steel stent (Jostent/Graftmaster), a self-expanding PTFE-covered Nitonol Stent (Symbiot) was used in all other cases. Intervention was performed with local anesthesia. Aspirin and Clopidogrel were both used as antiplatelet drugs. Clinical signs and symptoms and vascular imaging with DS, MR, CT angiography and ultrasound were recorded during patient follow-up, with a mean follow-up period of 14.6 months (4 - 30). Results: We were able to treat 8 out of 10 aneurysms (80 %) using covered stents. The aneurysms were immediately occluded and the associated stenoses of the parent vessel were eliminated. No clinically relevant complications occurred during the procedure or in the follow-up interval. In two cases, elongation of the carotid artery prevented the stent from being positioned over the aneurysm neck. These cases were shown to be stable with the use of antiplatelet drugs. Conclusion: Covered stents can be used in the treatment of pseudoaneurysms of the carotid artery as an alternative to long-term antithrombotic medication or surgery. In our study treatment was effective (80 %) and free of complications in the short- and mid-term follow-up. Possible indications, technique and the use of imaging modalities for patient follow-up are discussed. (orig.)

  9. Stent Fracture after Everolimus-Eluting Stent Implantation

    Directory of Open Access Journals (Sweden)

    Ali S. Almasood

    2011-01-01

    Full Text Available Compared with bare-metal stents, drug-eluting stents (DES have greatly reduced the risk of in-stent restenosis (ISR by inhibiting neointimal growth. Nevertheless, DES are still prone to device failure, which may lead to cardiac events. Recently, stent fracture (SF has emerged as a potential mechanism of DES failure that is associated with ISR. Stent fracture is strongly related to stent type, and prior reports suggest that deployment of sirolimus eluting stents (SES may be associated with a higher risk of SF compared to other DES. Everolimus eluting stents (EESs represent a new generation of DES with promising results. The occurrence of SF with EES has not been well established. The present paper describes two cases of EES fracture associated with ISR.

  10. Next generation covered stents made from nanocomposite materials: A complete assessment of uniformity, integrity and biomechanical properties.

    Science.gov (United States)

    Farhatnia, Yasmin; Pang, Jun Hon; Darbyshire, Arnold; Dee, Ryan; Tan, Aaron; Seifalian, Alexander M

    2016-01-01

    Covered stents are stents wrapped with a thin polymeric membrane, and are typically used to treat vessel aneurysms and seal perforated arteries. Current covered stents suffer from restenosis due to limitations in material and fabrication methods which leaves metallic struts directly exposed to blood. We have developed a biocompatible and haemocompatible nanocomposite polymer, polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU). We devised a novel combination of ultrasonic spray atomisation system and dip-coating process to produce small calibre covered stents with metal struts fully embedded within the membrane, which also yields greater coating uniformity. Stent-polymer bonding was enhanced via silanisation and coating of reactive pre-polymer. Platelet studies supported the non-thrombogenicity of POSS-PCU. Biomechanical performances including diametrical compliance, bending strength, radial strength and recoil were evaluated and optimised. This proof-of-principle manufacturing technique could lead to the development of next-generation small calibre adult and paediatric covered stents. These stents are currently undergoing preclinical trial. From the Clinical Editor: The use of stents to treat vascular diseases is now the standard of care in the clinical setting. Nonetheless, a major problem of the current stents is the risk of restenosis and thrombosis. The authors developed a nanocomposite material using polyhedral oligomeric silsesquioxane and poly(carbonate-urea) urethane (POSS-PCU) and incorporated into metallic stents. Preliminary data have already shown promising results. It is envisaged that this would further lead to better stent technology in the future. PMID:26238080

  11. Hemodynamics in Idealized Stented Coronary Arteries: Important Stent Design Considerations

    OpenAIRE

    Beier, Susann; Ormiston, John; Webster, Mark; Cater, John; Norris, Stuart; Medrano-Gracia, Pau; Young, Alistair; Cowan, Brett

    2015-01-01

    Stent induced hemodynamic changes in the coronary arteries are associated with higher risk of adverse clinical outcome. The purpose of this study was to evaluate the impact of stent design on wall shear stress (WSS), time average WSS, and WSS gradient (WSSG), in idealized stent geometries using computational fluid dynamics. Strut spacing, thickness, luminal protrusion, and malapposition were systematically investigated and a comparison made between two commercially available stents (Omega and...

  12. The risk and prognostic impact of definite stent thrombosis or in-stent restenosis after coronary stent implantation

    DEFF Research Database (Denmark)

    Thayssen, Per; Jensen, Lisette Okkels; Lassen, Jens Flensted;

    2012-01-01

    Aims: Data are limited on the prognostic impact of stent thrombosis and in-stent restenosis in patients treated with coronary stents. We examined the prognostic impact of stent thrombosis and in-stent restenosis in patients treated with percutaneous coronary intervention (PCI). Methods and results......: All patients who underwent stent implantation from 2002 to 2005 were identified in the Western Denmark Heart Registry. The hazard ratio (HR) for death associated with stent thrombosis or in-stent restenosis was estimated with a Cox regression analysis with stent thrombosis or in-stent restenosis...... as time-dependent variables. A total of 12,277 patients were treated with stent implantation. Stent thrombosis was observed in 111 (0.9%) patients and in-stent restenosis in 503 (4.1%) patients within 12 months after the index PCI. Occurrence of stent thrombosis was associated with an increased risk...

  13. Nanomaterial coatings applied on stent surfaces.

    Science.gov (United States)

    Bagheri, Mahsa; Mohammadi, Marzieh; Steele, Terry Wj; Ramezani, Mohammad

    2016-05-01

    The advent of percutaneous coronary intervention and intravascular stents has revolutionized the field of interventional cardiology. Nonetheless, in-stent restenosis, inflammation and late-stent thrombosis are the major obstacles with currently available stents. In order to enhance the hemocompatibility of stents, advances in the field of nanotechnology allow novel designs of nanoparticles and biomaterials toward localized drug/gene carriers or stent scaffolds. The current review focuses on promising polymers used in the fabrication of newer generations of stents with a short synopsis on atherosclerosis and current commercialized stents, nanotechnology's impact on stent development and recent advancements in stent biomaterials is discussed in context.

  14. Nanomaterial coatings applied on stent surfaces.

    Science.gov (United States)

    Bagheri, Mahsa; Mohammadi, Marzieh; Steele, Terry Wj; Ramezani, Mohammad

    2016-05-01

    The advent of percutaneous coronary intervention and intravascular stents has revolutionized the field of interventional cardiology. Nonetheless, in-stent restenosis, inflammation and late-stent thrombosis are the major obstacles with currently available stents. In order to enhance the hemocompatibility of stents, advances in the field of nanotechnology allow novel designs of nanoparticles and biomaterials toward localized drug/gene carriers or stent scaffolds. The current review focuses on promising polymers used in the fabrication of newer generations of stents with a short synopsis on atherosclerosis and current commercialized stents, nanotechnology's impact on stent development and recent advancements in stent biomaterials is discussed in context. PMID:27111467

  15. Future developments in biliary stenting

    Directory of Open Access Journals (Sweden)

    Hair CD

    2013-06-01

    Full Text Available Clark D Hair,1 Divyesh V Sejpal21Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA; 2Department of Medicine, Section of Gastroenterology, Hofstra North Shore-LIJ School of Medicine, North Shore University Hospital, Manhasset, NY, USAAbstract: Biliary stenting has evolved dramatically over the past 30 years. Advancements in stent design have led to prolonged patency and improved efficacy. However, biliary stenting is still affected by occlusion, migration, anatomical difficulties, and the need for repeat procedures. Multiple novel plastic biliary stent designs have recently been introduced with the primary goals of reduced migration and improved ease of placement. Self-expandable bioabsorbable stents are currently being investigated in animal models. Although not US Food and Drug Administration approved for benign disease, fully covered self-expandable metal stents are increasingly being used in a variety of benign biliary conditions. In malignant disease, developments are being made to improve ease of placement and stent patency for both hilar and distal biliary strictures. The purpose of this review is to describe recent developments and future directions of biliary stenting.Keywords: plastic stents, self-expandable metal stents, drug eluting stents, bioabsorbable stents, malignant biliary strictures, benign biliary strictures

  16. Biomimetic cardiovascular stents for in vivo re-endothelialization.

    Science.gov (United States)

    Liang, Chunyong; Hu, Yuecheng; Wang, Hongshui; Xia, Dan; Li, Qiang; Zhang, Jiao; Yang, Jianjun; Li, Baoe; Li, Haipeng; Han, Dong; Dong, Mingdong

    2016-10-01

    The use of cardiovascular stents for rapid in vivo re-endothelialization is a promising strategy for reducing cardiovascular implantation or preventing local thrombus formation and restenosis. Surface-patterned intravascular endoprosthetic stents have been developed to prevent life-threatening complications. In this study, vascular smooth muscle cell (VSMC)-biomimetic surface patterns were fabricated on 316L cardiovascular stents using a femtosecond laser and then implanted into the iliac artery of rabbit. The in vitro data revealed that the bionic surface patterns matched the morphology of the VSMCs well, which promotes the adhesion, proliferation, and migration of human umbilical vein endothelial cells. In addition, the patterned surfaces can significantly enhance re-endothelialization. Consequently, the surface biomimetic stent with the VSMC surface pattern is likely an effective approach to ensure rapid re-endothelialization and possibly reduce the incidence of in-stent restenosis. PMID:27380443

  17. Which spring is the best? Comparison of methods for virtual stenting.

    Science.gov (United States)

    Spranger, Katerina; Ventikos, Yiannis

    2014-07-01

    This paper presents a methodology for modeling the deployment of implantable devices used in minimally invasive vascular interventions. Motivated by the clinical need to perform preinterventional rehearsals of a stent deployment, we have developed methods enabling virtual device placement inside arteries, under the constraint of real-time application. This requirement of rapid execution narrowed down the search for a suitable method to the concept of a dynamic mesh. Inspired by the idea of a mesh of springs, we have found a novel way to apply it to stent modeling. The experiments conducted in this paper investigate properties of the stent models based on three different spring types: lineal, semitorsional, and torsional springs. Furthermore, this paper compares the results of various deployment scenarios for two different classes of devices: a stent graft and a flow diverter. The presented results can be of a high-potential clinical value, enabling the predictive evaluation of the outcome of a stent deployment treatment.

  18. Successful technical and clinical outcome using a second generation balloon expandable coronary stent for transplant renal artery stenosis: Our experience.

    Science.gov (United States)

    Salsamendi, Jason; Pereira, Keith; Baker, Reginald; Bhatia, Shivank S; Narayanan, Govindarajan

    2015-10-01

    Transplant renal artery stenosis (TRAS) is a vascular complication frequently seen because of increase in the number of renal transplantations. Early diagnosis and management is essential to optimize a proper graft function. Currently, the endovascular treatment of TRAS using angioplasty and/or stenting is considered the treatment of choice with the advantage that it does not preclude subsequent surgical correction. Treatment of TRAS with the use of stents, particularly in tortuous transplant renal anatomy presents a unique challenge to an interventional radiologist. In this study, we present three cases from our practice highlighting the use of a balloon-expandable Multi-Link RX Ultra coronary stent system (Abbott Laboratories, Abbott Park, Illinois, USA) for treating high grade focal stenosis along very tortuous renal arterial segments. Cobalt-Chromium alloy stent scaffold provides excellent radial force, whereas the flexible stent design conforms to the vessel course allowing for optimal stent alignment. PMID:26629289

  19. 光学相干断层成像评价植入不同药物洗脱架后的血管愈合情况%Evaluation by optical coherence tomography of vascular healing after drug-eluting stents implantation in acute myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    范春雨; Kim Jung-Sun; Kim Tae-Hoon; 吕吉元

    2011-01-01

    265 ± 130 μm, P < 0.0l ) and percentage of neointimal hyperplasia area ( SES 10 ± 8 vs PES 19 ± 8 vs ZES 28 ± 9, P <0.01 ), while percentage of uncovered struts were higher in SES and PES than in ZES (SES 15.1 ± 16 vs PES 7.1 ± 10 vs ZES 0.6 ± 1.5, P < 0.01 ).Malapposed struts were also more in SES and PES than in ZES [SES(3.8 ± 7.2)% vs PES (2.1 ± 4.4)% vs ZES (0±0)%, P<0.01].Higher prevalence of throumbus was found in SES and PES than in ZES ( SES 34% vs PES 33% vs ZES 6%, P < 0.05 ).Conclusions The rate of stent strut coverage and malapposition were significantly different among the DES types in acute myocardial infarction, therefore the type of DES might affect the vascular healing patterns in thrombotic lesions of acute myocardial infarction.

  20. In vitro study on the feasibility of magnetic stent hyperthermia for the treatment of cardiovascular restenosis

    OpenAIRE

    LI Li; Wang, Rui; Shi, Huan-Huan; Xie, Le; LI, JING-DING-SHA; KONG, WEI-CHAO; Tang, Jin-Tian; KE, DA-NIAN; ZHAO, LING-YUN

    2013-01-01

    Thermal treatment or hyperthermia has received considerable attention in recent years due to its high efficiency, safety and relatively few side-effects. In this study, we investigated whether it was possible to utilize targeted thermal or instent thermal treatments for the treatment of restenosis following percutaneous transluminal coronary angioplasty (PTCA) through magnetic stent hyperthermia (MSH). A 316L stainless steel stent and rabbit vascular smooth muscle cells (VSMCs) were used in t...

  1. Vascular Cures

    Science.gov (United States)

    ... our CEO Board of Directors Scientific Advisory Board History of Vascular Cures Impact Contact Us Vascular Disease What is Vascular Disease? Education and Awareness Vascular Diseases Abdominal Aortic Aneurysm Aortic ...

  2. The interactions between bloodstream and vascular structure on aortic dissecting aneurysmal model: A numerical study

    Science.gov (United States)

    Chen, Zeng-Sheng; Fan, Zhan-Ming; Zhang, Xi-Wen

    2013-06-01

    Stent-graft implantation is an important means of clinical treatment for aortic dissecting aneurysm (ADA). However, researches on fluid dynamics effects of stent were rare. Computer simulation was used to investigate the interactions between bloodstream and vascular structure in a stented ADA, which endures the periodic pulse velocity and pressure. We obtained and analyzed the flow velocity distribution, the wall displacement and wall stress in the ADA. By comparing the different results between a non-stented and a stented ADA, we found that the insertion of a vascular graft can make the location of maximum stress and displacement move from the aneurysm lumen wall to the artery wall, accompanied with a greatly decrease in value. These results imply that the placement of a stent-graft of any kind to occlude ADA will result in a decreased chance of rupture.

  3. Artificial Luminal Narrowing on Contrast-Enhanced Magnetic Resonance Angiograms on an Occasion of Stent-Assisted Coiling of Intracranial Aneurysm: In Vitro Comparison Using Two Different Stents with Variable Imaging Parameters

    Energy Technology Data Exchange (ETDEWEB)

    Seok, Jee Hyun; Choi, Hyun Seok; Jung, So Lyung; Ahn, Kook Jin; Kim, Myeong Jin; Shin, Yong Sam; Kim, Bum Soo [Seoul St. Mary' s Hospital, The Catholic University of Korea College of Medicine, Seoul (Korea, Republic of)

    2012-09-15

    Intracranial stenting for stent-assisted coiling of aneurysms requires adequate follow-up imaging. The aim of this in vitro study was to compare in-stent artificial luminal narrowing on contrast-enhanced MR angiograms (CE-MRA) when applying Neuroform and Enterprise stents for stent-assisted coiling. Two intracranial nitinol stents (Enterprise and Neuroform) were placed in silicon tubes and then imaged at 3 T and 1.5 T by the use of a T1-weighted three-dimensional spoiled gradient-echo sequence with minimal TR and TE. CE-MRAs were obtained by using different imaging planes, voxel sizes, and bandwidths, and with or without parallel imaging. Artificial lumen narrowing (ALN) was calculated and the results were compared. Lower magnetic field strength, axial plane perpendicular to axis of stent, and wider bandwidth resulted in a lower ALN on CE-MRA for both stents. Larger voxel size resulted in lower ALN for Neuroform stent. The parallel imaging acceleration factor did not affect ALN. The mean ALN was lower for Neuroform, but it was not significant by a paired t test. CE-MRA of the stented lumen of vascular phantom was partially impaired with ALN. Consequently, image plane orientation, magnetic field strength, bandwidth, and voxel size should be adjusted appropriately to reduce ALN.

  4. Artificial Luminal Narrowing on Contrast-Enhanced Magnetic Resonance Angiograms on an Occasion of Stent-Assisted Coiling of Intracranial Aneurysm: In Vitro Comparison Using Two Different Stents with Variable Imaging Parameters

    International Nuclear Information System (INIS)

    Intracranial stenting for stent-assisted coiling of aneurysms requires adequate follow-up imaging. The aim of this in vitro study was to compare in-stent artificial luminal narrowing on contrast-enhanced MR angiograms (CE-MRA) when applying Neuroform and Enterprise stents for stent-assisted coiling. Two intracranial nitinol stents (Enterprise and Neuroform) were placed in silicon tubes and then imaged at 3 T and 1.5 T by the use of a T1-weighted three-dimensional spoiled gradient-echo sequence with minimal TR and TE. CE-MRAs were obtained by using different imaging planes, voxel sizes, and bandwidths, and with or without parallel imaging. Artificial lumen narrowing (ALN) was calculated and the results were compared. Lower magnetic field strength, axial plane perpendicular to axis of stent, and wider bandwidth resulted in a lower ALN on CE-MRA for both stents. Larger voxel size resulted in lower ALN for Neuroform stent. The parallel imaging acceleration factor did not affect ALN. The mean ALN was lower for Neuroform, but it was not significant by a paired t test. CE-MRA of the stented lumen of vascular phantom was partially impaired with ALN. Consequently, image plane orientation, magnetic field strength, bandwidth, and voxel size should be adjusted appropriately to reduce ALN.

  5. Drug-eluting stents: current issues

    NARCIS (Netherlands)

    P.W.J.C. Serruys (Patrick); A.T.L. Ong (Andrew)

    2005-01-01

    textabstractEarly stent thrombosis occurs in about 1% to 1.5% of patients with drug-eluting stents, very similar to the rate with bare-metal stents. Late stent thrombosis is more of a concern with drug-eluting stents, with an incidence of at least 0.35%. I would urge caution if you feel you have to

  6. Bioresorbable vascular scaffold for the treatment of coronary bifurcations: What have we learned?

    Science.gov (United States)

    Belardi, Jorge A; Albertal, Mariano

    2015-10-01

    Bioresorbable vascular scaffolds (BVS) remain experimental for the treatment of coronary bifurcations (B) and further clinical data is needed before widespread adoption in this setting. Preliminary, clinical outcome in B using a provisional stenting or double stenting approach with BVS is encouraging and close to the one observed with next-generation drug-eluting stent. Improvements in device navigability, reduction in strut bulk and reabsorption time may render the device more predictable and simpler to use.

  7. Capture of circulatory endothelial progenitor cells and accelerated re-endothelialization of a bio-engineered stent in human ex vivo shunt and rabbit denudation model

    NARCIS (Netherlands)

    K. Larsen (Katarína); K.L. Cheng (Caroline); D. Tempel (Dennie); S. Parker (Sherry); S. Yazdani (Saami); W.K. den Dekker (Wijnand); H.J. Houtgraaf (Jaco); R. de Jong (Renate); S. Swager-ten Hoor (Stijn); E. Ligtenberg (Erik); S.R. Hanson (Stephen); R. Rowland (Steve); F. Kolodgie (Frank); P.W.J.C. Serruys (Patrick); R. Virmani (Renu); H.J. Duckers (Henricus)

    2012-01-01

    textabstractThe Genous™ Bio-engineered R™ stent (GS) aims to promote vascular healing by capture of circulatory endothelial progenitor cells (EPCs) to the surface of the stent struts, resulting in accelerated re-endothelialization. Here, we assessed the function of the GS in comparison to bare-metal

  8. Self-expandable metalic endotracheal stent

    International Nuclear Information System (INIS)

    Six bare stents and six covered stents were inserted in the trachea of 12 dogs under general anesthesia. After 1-10 weeks of observation, the dogs were killed, and the trachea and lung were examined grossly and histologically. Pneumonia and stent migration were observed more frequently at covered stent group. Inflammatory change of the trachea was more severe at covered stent group. In conclusion, we believe that it is inadequate to insert silicone covered stent in the tracheobronchial tree. (Author)

  9. Asymmetric collider

    International Nuclear Information System (INIS)

    The study of CP violation in beauty decay is one of the key challenges facing high energy physics. Much work has not yielded a definitive answer how this study might best be performed. However, one clear conclusion is that new accelerator facilities are needed. Proposals include experiments at asymmetric electron-positron colliders and in fixed-target and collider modes at LHC and SSC. Fixed-target and collider experiments at existing accelerators, while they might succeed in a first observation of the effect, will not be adequate to study it thoroughly. Giomataris has emphasized the potential of a new approach to the study of beauty CP violation: the asymmetric proton collider. Such a collider might be realized by the construction of a small storage ring intersecting an existing or soon-to-exist large synchrotron, or by arranging collisions between a large synchrotron and its injector. An experiment at such a collider can combine the advantages of fixed-target-like spectrometer geometry, facilitating triggering, particle identification and the instrumentation of a large acceptance, while the increased √s can provide a factor > 100 increase in beauty-production cross section compared to Tevatron or HERA fixed-target. Beams crossing at a non-zero angle can provide a small interaction region, permitting a first-level decay-vertex trigger to be implemented. To achieve large √s with a large Lorentz boost and high luminosity, the most favorable venue is the high-energy booster (HEB) at the SSC Laboratory, though the CERN SPS and Fermilab Tevatron are also worth considering

  10. Delayed complications after flow-diverter stenting: reactive in-stent stenosis and creeping stents.

    Science.gov (United States)

    Cohen, José E; Gomori, John Moshe; Moscovici, Samuel; Leker, Ronen R; Itshayek, Eyal

    2014-07-01

    We assessed the frequency and severity of changes in stent configuration and location after the treatment of intracranial aneurysms, and patterns of in-stent stenosis. We retrospectively reviewed data for consecutive aneurysm patients managed with endovascular implantation of flow-diverter stents (Silk Flow Diverter [Balt Extrusion, Montmorency, France] and Pipeline Embolization Device [ev3/Coviden, Minneapolis, MN, USA]) from October 2011 to July 2012. Routine 2, 6, 9-12, and 16-20 month follow-up angiograms were compared, with a focus on changes in stent configuration and location from immediately after deployment to angiographic follow-up, and the incidence and development of in-stent stenosis. Thirty-four patients with 42 aneurysms met inclusion criteria. The Silk device was implanted in 16 patients (47%, single device in 15), the Pipeline device in 18 (53%, single device in 16). On first follow-up angiography, in-stent stenosis was observed in 38% of Silk devices and 39% of Pipeline devices. In-stent stenosis was asymptomatic in 12 of 13 patients. One woman presented with transient ischemic attacks and required stent angioplasty due to end tapering and mild, diffuse in-stent stenosis. Configuration and location changes, including stent creeping and end tapering were seen in 2/16 patients (13%) with Silk devices, and 0/18 patients with Pipeline devices. We describe stent creeping and end tapering as unusual findings with the potential for delayed clinical complications. In-stent stenosis, with a unique behavior, is a frequent angiographic finding observed after flow-diverter stent implant. The stenosis is usually asymptomatic; however, close clinical and angiographic monitoring is mandatory for individualized management.

  11. Successive breaks in biliary stents.

    Science.gov (United States)

    Espinel, Jesús; Pinedo, Eugenia; Ojeda, Vanesa; Guerra, María

    2016-04-01

    A 64 year-old male, was diagnosed with obstructive jaundice due to a well-differentiated pancreatic neuroendocrine tumor with liver metastases. The patient underwent endoscopic placement of covered self-expanding biliary stent (10x60 mm, Hanaro) by ERCP. He was admitted with cholangitis one year later. The following ERCP revealed a fractured stent with loss of the distal end (duodenal) and partial migration of the remaining stent to the common bile duct. The fragmented stent was removed from the common bile duct and a new, similar one was inserted. Four months later the patient was admitted with cholangitis. A new ERCP was done and biliary stent was also fragmented. It was removed and an uncovered stent (Wallflex) was inserted. PMID:27065248

  12. Short-term safety and efficacy of the biodegradable iron stent in mini-swine coronary arteries

    Institute of Scientific and Technical Information of China (English)

    WU Chao; QIU Hong; HU Xiao-ying; RUAN Ying-mao; TIAN Yi; CHU Yan; XU Xin-lin

    2013-01-01

    Background To overcome the drawbacks of permanent stents,biodegradable stents have been studied in recent years.The bioabsorbable polymer vascular scaffold (BVS) was the first bioabsorbable stent to undergo clinical trials,demonstrating safety and feasibility in the ABSORB studies.Iron can potentially serve as the biomaterial for biodegradable stents.This study aimed to assess the short-term safety and efficacy of a biodegradable iron stent in mini-swine coronary arteries.Methods Eight iron stents and eight cobalt chromium alloy (VISION) control stents were randomly implanted into the LAD and RCA of eight healthy mini-swine,respectively.Two stents of the same metal base were implanted into one animal.At 28 days the animals were sacrificed after coronary angiography,and histopathological examinations were performed.Results Histomorphometric measurements showed that mean neointimal thickness ((0.46±0.17) mm vs.(0.45±0.18)mm,P=0.878),neointimal area ((2.55±0.91) mm2 vs.(3.04±1.15) mm2,P=0.360) and percentage of area stenosis ((44.50±11.40)% vs.(46.00±17.95)%,P=0.845) were not significantly different between the iron stents and VISION stents.There was no inflammation,thrombosis or necrosis in either group.The scanning electron microscopy (SEM) intimal injury scores (0.75±1.04 vs.0.88±0.99,P=0.809) and number of proliferating cell nuclear antigen (PCNA) positive staining cells were not significantly different between the two groups.The percentage of neointimal coverage by SEM examination was numerically higher in iron stents than in VISION stents ((84.38±14.50)% vs.(65.00±22.04)%,P=0.057),but the difference was not statistically significant.Iron staining in the tissue surrounding the iron stents at 28 days was positive and the vascular wall adjacent to the iron stent had a brownish tinge,consistent with iron degradation.No abnormal histopathological changes were detected in coronary arteries or major organs.Conclusions The biodegradable iron stent has

  13. Future developments in biliary stenting

    OpenAIRE

    Hair CD; Sejpal DV

    2013-01-01

    Clark D Hair,1 Divyesh V Sejpal21Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, Houston, TX, USA; 2Department of Medicine, Section of Gastroenterology, Hofstra North Shore-LIJ School of Medicine, North Shore University Hospital, Manhasset, NY, USAAbstract: Biliary stenting has evolved dramatically over the past 30 years. Advancements in stent design have led to prolonged patency and improved efficacy. However, biliary stenting is still affected...

  14. Mechanical thrombectomy using Rotarex system and stent-in-stent placement for treatment of distal femoral artery occlusion secondary to stent fracture – a case report and literature review

    International Nuclear Information System (INIS)

    Treatment of peripheral arterial diseases may be distinguished into conservative and interventional management; the latter is divided into surgical and endovascular procedures. Management of peripheral artery stenosis and occlusion with vascular stents is associated with the risk of late complications such as restenosis, stent fracture or dislocation. A 62-year-old woman with generalized atherosclerosis, particularly extensive in lower limb arteries, was admitted to the Department of Angiology 11 months after having an endovascular procedure performed due to critical ischemia of left lower limb. Because of stent occlusion, a decision to perform angiographic examination of lower limb arteries was made. Examination revealed occlusion of the superficial femoral artery along its entire length, including previously implanted stents. Distal stent was fractured with slight dislocation of the proximal segment. A decision was made to perform mechanical thrombectomy using a Rotarex system followed by a stent-in-stent placement procedure. Follow-up angiography and ultrasound scan performed 24 hours after the procedure revealed a patent vessel with satisfactory blood flow. Nowadays, imaging diagnostics of peripheral artery stenosis involves non-invasive examinations such as ultrasound, minimally invasive examinations such as angio-MRI and MDCT, or invasive examinations such as DSA and IVUS. DSA examinations are used to confirm significant stenosis or occlusion of a vessel, particularly when qualifying a patient for endovascular treatment. Due to their anatomic location, the superficial femoral artery and the popliteal artery are subject to various forces e.g. those exerted by the working muscles. Mechanical thrombectomy and atherectomy are efficient methods of arterial recanalization used in the treatment of acute, subacute or even chronic occlusions or stenosis of peripheral vessels. Frequency of angioplasty and vascular stent implantation procedures is increased in patients

  15. Angioplasty and stent - heart - discharge

    Science.gov (United States)

    Drug-eluting stents - discharge; PCI - discharge; Percutaneous coronary intervention - discharge; Balloon angioplasty - discharge; Coronary angioplasty - discharge; Coronary artery angioplasty - discharge; Cardiac ...

  16. Clinical Events and Patient-Reported Chest Pain in All-Comers Treated With Resolute Integrity and Promus Element Stents : 2-Year Follow-Up of the DUTCH PEERS (DUrable Polymer-Based STent CHallenge of Promus ElemEnt Versus ReSolute Integrity) Randomized Trial (TWENTE II)

    NARCIS (Netherlands)

    Sen, Hanim; Lam, Ming Kai; Löwik, Marije M.; Danse, Peter W.; Jessurun, Gillian A.J.; Houwelingen, van K. Gert; Anthonio, Rutger; Gin, R. Melvyn Tjon Joe; Hautvast, Raymond W.M.; Louwerenburg, J. (Hans) W.; Man, de Frits H.A.F.; Stoel, Martin G.; Heijden, van der Liefke C.; Linssen, Gerard C.M.; IJzerman, Maarten J.; Tandjung, Kenneth; Doggen, Carine J.M.; Birgelen, von Clemens

    2015-01-01

    Objectives This study assessed clinical events and patient-reported chest pain 2 years after treatment of all-comers with Resolute Integrity zotarolimus-eluting stents (Medtronic Vascular, Santa Rosa, California) and Promus Element everolimus-eluting stents (Boston Scientific, Natick, Massachusetts)

  17. Nasal packing and stenting

    Directory of Open Access Journals (Sweden)

    Weber, Rainer K.

    2009-01-01

    Full Text Available Nasal packs are indispensable in ENT practice. This study reviews current indications, effectiveness and risks of nasal packs and stents. In endoscopic surgery, nasal packs should always have smooth surfaces to minimize mucosal damage, improve wound healing and increase patient comfort. Functional endoscopic endonasal sinus surgery allows the use of modern nasal packs, since pressure is no longer required. So called hemostatic/resorbable materials are a first step in this direction. However, they may lead to adhesions and foreign body reactions in mucosal membranes. Simple occlusion is an effective method for creating a moist milieu for improved wound healing and avoiding dryness. Stenting of the frontal sinus is recommended if surgery fails to produce a wide, physiologically shaped drainage path that is sufficiently covered by intact tissue.

  18. Investigating Surface Topology and Cyclic-RGD Peptide functionalization on Vascular Endothelialization

    OpenAIRE

    McNichols, Colton; Wilkins, Justin; Kubota, Atsu; Shiu, Yan T.; Aouadi, Samir M.; Kohli, Punit

    2013-01-01

    The advantages of endothelialization of a stent surface in comparison with the bare metal and drug eluting stents used today include reduced late-stent restenosis and in-stent thrombosis. In this paper, we study the effect of surface topology and functionalization of tantalum (Ta) with cyclic-(arginine-glycine-aspartic acid-D-phenylalanine-lysine (cRGDfK)) on the attachment, spreading, and growth of vascular endothelial cells. Self-assembled nano-dimpling on Ta surfaces was performed using a ...

  19. Clinical results of carotid artery stenting with a nitinol self-expanding stent (SMART stent)

    Energy Technology Data Exchange (ETDEWEB)

    Drescher, Robert; Mathias, Klaus D.; Jaeger, Horst J.; Bockisch, Georg; Demirel, Eren; Gissler, Martin H.; Hauth, Elke [Department of Radiology, Staedtische Kliniken Dortmund, Beurhausstrasse 40, 44139 Dortmund (Germany); Department of Radiology and Microtherapy, University Witten/Herdecke (Germany)

    2002-10-01

    Our objective was to assess the technical feasibility and the clinical results of internal carotid artery (ICA) stenting using a nitinol self-expanding stent (SMART stent). In 13 patients 13 high-grade stenoses of the internal carotid artery were treated via an implantation of a SMART stent. In all cases a predilation of the stenosis and a postdilation within the stent were performed. Follow-up examinations were carried out in all patients after a period of 6 months. In each case the implantation of the stent was performed without technical complications. In 12 of 13 cases the stent was placed in the patients' internal carotid artery, in 1 case from the internal to the common carotid artery (CCA). The average degree of stenosis of 78% (70-95%) was reduced to an average of 2.8% (0-21%). The 6-month follow-up angiography showed an average degree of restenosis of 11.8% (0-29%) in 8 of 13 patients. Duplex sonography in the remaining 5 patients demonstrated patent stents. One patient showed brief neurological symptoms during the intervention. No further complications occurred during follow-up time. Treatment of internal carotid artery stenosis with the SMART stent seems technically feasible, safe, and promises long-term patency. (orig.)

  20. Hemodynamics in Idealized Stented Coronary Arteries: Important Stent Design Considerations.

    Science.gov (United States)

    Beier, Susann; Ormiston, John; Webster, Mark; Cater, John; Norris, Stuart; Medrano-Gracia, Pau; Young, Alistair; Cowan, Brett

    2016-02-01

    Stent induced hemodynamic changes in the coronary arteries are associated with higher risk of adverse clinical outcome. The purpose of this study was to evaluate the impact of stent design on wall shear stress (WSS), time average WSS, and WSS gradient (WSSG), in idealized stent geometries using computational fluid dynamics. Strut spacing, thickness, luminal protrusion, and malapposition were systematically investigated and a comparison made between two commercially available stents (Omega and Biomatrix). Narrower strut spacing led to larger areas of adverse low WSS and high WSSG but these effects were mitigated when strut size was reduced, particularly for WSSG. Local hemodynamics worsened with luminal protrusion of the stent and with stent malapposition, adverse high WSS and WSSG were identified around peak flow and throughout the cardiac cycle respectively. For the Biomatrix stent, the adverse effect of thicker struts was mitigated by greater strut spacing, radial cell offset and flow-aligned struts. In conclusion, adverse hemodynamic effects of specific design features (such as strut size and narrow spacing) can be mitigated when combined with other hemodynamically beneficial design features but increased luminal protrusion can worsen the stent's hemodynamic profile significantly.

  1. A randomized multicenter comparison of hybrid sirolimus-eluting stents with bioresorbable polymer versus everolimus-eluting stents with durable polymer in total coronary occlusion: rationale and design of the Primary Stenting of Occluded Native Coronary Arteries IV study

    Directory of Open Access Journals (Sweden)

    Teeuwen Koen

    2012-12-01

    Full Text Available Abstract Background Percutaneous recanalization of total coronary occlusion (TCO was historically hampered by high rates of restenosis and reocclusions. The PRISON II trial demonstrated a significant restenosis reduction in patients treated with sirolimus-eluting stents compared with bare metal stents for TCO. Similar reductions in restenosis were observed with the second-generation zotarolimus-eluting stent and everolimus-eluting stent. Despite favorable anti-restenotic efficacy, safety concerns evolved after identifying an increased rate of very late stent thrombosis (VLST with drug-eluting stents (DES for the treatment of TCO. Late malapposition caused by hypersensitivity reactions and chronic inflammation was suggested as a probable cause of these VLST. New DES with bioresorbable polymer coatings were developed to address these safety concerns. No randomized trials have evaluated the efficacy and safety of the new-generation DES with bioresorbable polymers in patients treated for TCO. Methods/Design The prospective, randomized, single-blinded, multicenter, non-inferiority PRISON IV trial was designed to evaluate the safety, efficacy, and angiographic outcome of hybrid sirolimus-eluting stents with bioresorbable polymers (Orsiro; Biotronik, Berlin, Germany compared with everolimus-eluting stents with durable polymers (Xience Prime/Xpedition; Abbott Vascular, Santa Clara, CA, USA in patients with successfully recanalized TCOs. In total, 330 patients have been randomly allocated to each treatment arm. Patients are eligible with estimated duration of TCO ≥4 weeks with evidence of ischemia in the supply area of the TCO. The primary endpoint is in-segment late luminal loss at 9-month follow-up angiography. Secondary angiographic endpoints include in-stent late luminal loss, minimal luminal diameter, percentage of diameter stenosis, in-stent and in-segment binary restenosis and reocclusions at 9-month follow-up. Additionally, optical coherence

  2. Stent-based delivery of triptolide reduces neointimal formation in rabbit iliac arteries

    Institute of Scientific and Technical Information of China (English)

    CHEN Ming; WANG Kai-xia; LIU Zhao-ping; HUO Yong

    2005-01-01

    @@ The long-term clinical efficacy of intracoronary stenting is limited by restenosis, which occurs in 15% to 30% of patients.1 In-stent restenosis is solely due to neointimal hyperplasia. Stent-based delivery of sirolimus, which inhibits intimal proliferation by blocking the G1/S transition, has been successfully used to prevent in-stent restenosis in clinical practice. Previous studies have shown that triptolide inhibited the DNA synthesis of vascular smooth muscle cells by blocking the transition from G0/G1 to S phase,2 suggesting that triptolide could be useful for preventing restenosis. The potential unwanted side effects limits the use of systemic administration of this agent for the prevention of in-stent restenosis. Local delivery using a stent platform, however, might allow deposition of a therapeutic triptolide concentration in the arterial wall, with a substantially reduced risk of systemic toxicity. The purpose of the present study was to determine the efficacy of stent-based delivery of triptolide.

  3. The stress-strain behavior of coronary stent struts is size dependent.

    Science.gov (United States)

    Murphy, B P; Savage, P; McHugh, P E; Quinn, D F

    2003-06-01

    Coronary stents are used to re-establish the vascular lumen and flow conditions within the coronary arteries; the typical thickness of a stent strut is 100 microm, and average grain sizes of approximately 25 microm exist in stainless steel stents. The purpose of this study is to investigate the effect of strut size on the stress strain behavior of 316 L stainless steel. Other materials have shown a size dependence at the micron size scale; however, at present there are no studies that show a material property size dependence in coronary stents. Electropolished stainless steel stent struts within the size range of 60-500 microm were tensile tested. The results showed that within the size range of coronary stent struts a size dependent stress-strain relationship is required to describe the material. Finite element models of the final phase of fracture, i.e., void growth models, explained partially the reason for this size effect. This study demonstrated that a size based stress-strain relationship must be used to describe the tensile behavior material of 316 L stainless steel at the size scale of coronary stent struts.

  4. Simple mesh stent placement for treating intracranial aneurysm: progress in research

    International Nuclear Information System (INIS)

    Treatment of an aneurysm with a mesh stent alone becomes an emerging technique. The mechanism involves the mesh stents, when it crosses the neck of an aneurysm could change the internal circulation and induce the formation of stable thrombus and in turn assists the growth of neointima for anatomical healing of the aneurysmal neck. The mesh stent technique aimed at vascular reconstruction with expected curing effect for aneurysm together as a simple and safe way to keep the patency of the small arterial branches, just contrary to the covered stent. This technique couldn't be carried out practically in wide scale because of immaturity, therefore we give a comprehesive review in the progress of this field. (authors)

  5. Randomized clinical trial comparing abluminal biodegradable polymer sirolimus-eluting stents with durable polymer sirolimus-eluting stents

    Science.gov (United States)

    Zhang, Haijun; Wang, Xiangfei; Deng, Wei; Wang, Shenguo; Ge, Junbo; Toft, Egon

    2016-01-01

    Abstract Background: The biodegradable polymer drug-eluting stents (DES) were developed to improve vascular healing. However, further data and longer-term follow-up are needed to confirm safety and efficacy of these stents. This randomized clinical trial aimed to compare safety and efficacy of 2 sirolimus-eluting stents (SES): Cordimax—a novel abluminal biodegradable polymer SES and Cypher Select—a durable polymer SES, at 9 months angiographic and 5-year clinical follow-up. Methods: We randomized 402 patients with coronary artery disease to percutaneous coronary intervention with Cordimax (n = 202) or Cypher select (n = 200). Angiographic follow-up was performed at 9 months after the index procedure and clinical follow-up annually up to 5 years. The primary endpoint was angiographic in-stent late luminal loss (LLL). Secondary endpoints included angiographic restenosis rate, target vessel revascularization (TVR), and major adverse cardiac events (MACEs; defined as cardiac death, myocardial infarction, or TVR) at 5-year follow-up. Results: Cordimax was noninferior to Cypher select for in-stent LLL (0.25 ± 0.47 vs 0.18 ± 0.49 mm; P = 0.587) and in-stent mean diameter stenosis (22.19 ± 12.21% vs 19.89 ± 10.79%; P = 0.064) at 9 months angiographic follow-up. The MACE rates were not different at 1 year (5.9% vs 4.0%, P = 0.376); however, MACE rates from 2 to 5 years were lower in the Cordimax group (6.8% vs 13.1%; P = 0.039). Conclusion: Abluminal biodegradable polymer SES is noninferior to durable polymer SES at 9-month angiographic and 1-year clinical follow-up. However, MACE rates from 2 to 5 years were less in the abluminal biodegradable polymer group. PMID:27661023

  6. Development of a dynamic in vitro model of a stented blood vessel to evaluate the effects of stent strut material selection and surface coating on smooth muscle cell response

    Science.gov (United States)

    Winn, Bradley Huegh

    Cardiovascular disease is the leading cause of mortality in The United States and Europe, accounting for approximately half of all deaths. The most common form of cardiovascular disease is atherosclerosis, which is characterized by the formation of fatty atheromatous plaques that can grow to occlude the vessel lumen, thus causing ischemia distal to the occlusion. This is commonly treated using balloon angioplasty, which is usually done in conjunction with the deployment of a stent. Stent deployment helps hold the vessel open following the local injury caused by balloon inflation and prevents elastic recoil and subsequent negative remodeling. Stenting has been shown to significantly reduce restenosis rates from approximately 20-50% without a stent to about 10-30% with stent deployment. However, restenosis still remains the main cause of long-term stent failure. In basic terms, a balloon angioplasty procedure is a forceful displacement of an atherosclerotic lesion serving to widen the vessel lumen to increase blood flow. This procedure causes stretching of the vessel wall, tears in the atherosclerotic plaques, and general damage to the vessel in turn signaling a complex cascade of thrombosis, inflammation, intimal thickening, and vascular remodeling. Stent deployment also further complicates the immunological response by triggering a foreign body response from the implantation of a biomaterial into the body. When performing an angioplasty procedure, particularly in conjunction with stent deployment, a certain degree of vascular injury is inevitable. However, the initial injury can be further complicated by the body's local reaction to the implanted biomaterial, the severity of which can ultimately dictate the degree of restenosis and subsequently affect procedural success. The proliferative response of VSMCs to the various afore mentioned stimuli results in the formation of often copious amounts of neointimal tissue, generally known as intimal hyperplasia. The

  7. Carotid angioplasty and stenting in the elderly

    International Nuclear Information System (INIS)

    To investigate the technical success rate as well as the procedural and mid-term complication rates of carotid angioplasty and stenting in elderly patients, a group excluded from large randomized endarterectomy trials given their perceived high surgical risk. Of 200 consecutive carotid angioplasty and/or stenting procedures performed between March 1996 and March 2005, 21 procedures were performed without cerebral protection devices in 20 patients over the age of 79 years (mean age: 83 years, 12 men, eight women). These patients' medical records were retrospectively reviewed for vascular imaging reports and available clinical follow-up. Procedural and mid-term complication rates were calculated and compared to a previously published cohort of 133 consecutive patients ≤79 years of age who also underwent endovascular treatment at our institution. Carotid stenosis was reduced from a mean of 82% to no significant stenosis in all procedures. The procedural stroke rate was zero of 21 procedures. The procedural transient ischemic attack rate (TIA) was one of 21 procedures (4.8%). Mean follow-up was 24.6 months (range: 1.0-79.5 months) with at least a 30-day follow-up for 20 of the 21 procedures (95.2%). There were no new strokes. There was one recurrent ipsilateral TIA at 1.9 months. In five cases with follow-up carotid ultrasonography, no hemodynamically significant restenosis had occurred. There were three myocardial infarctions (MI) occurring at 0.5, 2.1, and 15.2 months, of which the last MI was fatal. The composite 30-day stroke and death rate was zero of 21 procedures (95% confidence interval: 0-14%). No significant difference was found in the 30-day rate of stroke, TIA, MI, or death between the elderly and younger patients. Carotid angioplasty and stenting in elderly patients can be performed successfully with acceptable procedural and mid-term complication rates comparable to younger patients. (orig.)

  8. Carotid angioplasty and stenting in the elderly

    Energy Technology Data Exchange (ETDEWEB)

    Kadkhodayan, Yasha [Washington University School of Medicine, Interventional Neuroradiology, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Cross, DeWitte T.; Moran, Christopher J. [Washington University School of Medicine, Interventional Neuroradiology, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Washington University School of Medicine, Department of Neurological Surgery, St. Louis, MO (United States); Derdeyn, Colin P. [Washington University School of Medicine, Interventional Neuroradiology, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Washington University School of Medicine, Department of Neurological Surgery, St. Louis, MO (United States); Washington University School of Medicine, Department of Neurology, St. Louis, MO (United States)

    2007-11-15

    To investigate the technical success rate as well as the procedural and mid-term complication rates of carotid angioplasty and stenting in elderly patients, a group excluded from large randomized endarterectomy trials given their perceived high surgical risk. Of 200 consecutive carotid angioplasty and/or stenting procedures performed between March 1996 and March 2005, 21 procedures were performed without cerebral protection devices in 20 patients over the age of 79 years (mean age: 83 years, 12 men, eight women). These patients' medical records were retrospectively reviewed for vascular imaging reports and available clinical follow-up. Procedural and mid-term complication rates were calculated and compared to a previously published cohort of 133 consecutive patients {<=}79 years of age who also underwent endovascular treatment at our institution. Carotid stenosis was reduced from a mean of 82% to no significant stenosis in all procedures. The procedural stroke rate was zero of 21 procedures. The procedural transient ischemic attack rate (TIA) was one of 21 procedures (4.8%). Mean follow-up was 24.6 months (range: 1.0-79.5 months) with at least a 30-day follow-up for 20 of the 21 procedures (95.2%). There were no new strokes. There was one recurrent ipsilateral TIA at 1.9 months. In five cases with follow-up carotid ultrasonography, no hemodynamically significant restenosis had occurred. There were three myocardial infarctions (MI) occurring at 0.5, 2.1, and 15.2 months, of which the last MI was fatal. The composite 30-day stroke and death rate was zero of 21 procedures (95% confidence interval: 0-14%). No significant difference was found in the 30-day rate of stroke, TIA, MI, or death between the elderly and younger patients. Carotid angioplasty and stenting in elderly patients can be performed successfully with acceptable procedural and mid-term complication rates comparable to younger patients. (orig.)

  9. Incidence of definite stent thrombosis or in-stent restenosis after drug-eluting stent implantation for treatment of coronary in-stent restenosis

    DEFF Research Database (Denmark)

    Jensen, Jesper Khedri; Jensen, Lisette Okkels; Terkelsen, Christian Juhl;

    2013-01-01

    There are limited data on the optimal management of in-stent restenosis after percutaneous coronary intervention (PCI) with bare metal stent (BMS) or drug-eluting stent (DES) implantations. We assessed the clinical presentation, the incidence, and prognosis of definite stent thrombosis...

  10. Percutaneous biliary drainage and stenting

    International Nuclear Information System (INIS)

    Full text: Percutaneous transhepatic cholangiography (PTC) is an X-ray or US guided procedure that involves the injection of a contrast material directly into the bile ducts inside the liver to produce pictures of them. If a blockage or narrowing is found, additional procedures may be performed: 1. insertion of a catheter to drain excess bile out of the body or both - internal and external; 2. plastic endoprothesis placement; 3. self-expandable metal stents placement to help open bile ducts or to bypass an obstruction and allow fluids to drain. Current percutaneous biliary interventions include percutaneous transhepatic cholangiography (PTC) and biliary drainage to manage benign and malignant obstructions. Internal biliary stents are either plastic or metallic, and various types of each kind are available. Internal biliary stents have several advantages. An external tube can be uncomfortable and have a psychological disadvantage. An internal stent prevents the problems related to external catheters, for example, pericatheter leakage of bile and the need for daily flushing. The disadvantages include having to perform endoscopic retrograde cholangiopancreatography (ERCP) or new PTC procedures to obtain access in case of stent obstruction. Better patency rates are reported with metallic than with plastic stents in cases of malignant obstruction, though no effect on survival is noted. Plastic internal stents are the cheapest but reportedly prone to migration. Metallic stents are generally not used in the treatment of benign disease because studies have shown poor long-term patency rates. Limited applications may include the treatment of patients who are poor surgical candidates or of those in whom surgical treatment fails. Most postoperative strictures are treated surgically, though endoscopic and (less commonly) percutaneous placement of nonmetallic stents has increasingly been used in the past few years. Now there are some reports about use of biodegradable biliary

  11. Development of epigallocatechin gallate-eluting polymeric stent and its physicochemical, biomechanical and biological evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dong-Wook [Department of Nanomedical Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Busan 609-735 (Korea, Republic of); Lee, Jun Jae [Division of Advanced Fibro-Science, Kyoto Institute of Technology, Kyoto 606-8585 (Japan); Jung, Duk-Young [Senior Products Industrial Center, Busan Techno-Park, Busan-617-030 (Korea, Republic of); Park, Jong-Chul [Cellbiocontrol Laboratory, Department of Medical Engineering, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of); Hyon, Suong-Hyu, E-mail: nanohan@pusan.ac.k, E-mail: biogen@frontier.kyoto-u.ac.j [Department of Medical Simulation Engineering, Institute for Frontier Medical Sciences, Kyoto University, Kyoto 606-8507 (Japan)

    2009-08-15

    Localized drug delivery from drug-eluting stents has been accepted as one of the most promising treatment methods for preventing restenosis after stenting. However, hypersensitivity reactions caused by their nonresorbable polymer coatings and bare-metal stents may result in serious clinical sequelae. Epigallocatechin-3-O-gallate (EGCG), the predominant catechin from tea, has been shown to exert anti-thrombotic, anti-inflammatory and anti-proliferative activities. In this study, it was hypothesized that sustainedly released EGCG from biodegradable poly(lactide-co-epsilon-caprolactone, PLCL) would suppress the proliferation of vascular smooth muscle cells (VSMCs). EGCG-releasing PLCL (E-PLCL) was prepared by blending PLCL with EGCG. The surface morphology, roughness and melting temperature of PLCL were not changed despite EGCG addition. EGCG was uniformly dispersed into E-PLCL and sustainedly released for periods up to 7 days by controlled diffusion rather than PLCL degradation. Moreover, EGCG did not affect tensile strength at break, but significantly increased the elastic modulus of PLCL. The proliferation of VSMCs onto E-PLCL was significantly suppressed although the cell attachment onto E-PLCL had been higher than that onto PLCL. On the other hand, EGCG-eluting polymeric stents were prepared with neither cracks nor webbings between struts, and their structural integrity was maintained without delamination or destruction. These results suggest that E-PLCL can be potentially applied for fabricating an EGCG-eluting vascular stent, namely an EGCG-eluting polymeric stent, or even an EGCG-releasing polymer-coated metal stent, to prevent thrombosis, inflammation and in-stent restenosis.

  12. Coronary stent technology: a narrative review.

    Science.gov (United States)

    Chen, Daniel; Jepson, Nigel

    2016-09-19

    Coronary angioplasty and coronary artery stents have revolutionised interventional cardiology. Contemporary coronary stent technology continues to seek to improve on the outcomes of the preceding generation of devices by refining their design, structure and component materials. These technologies include new generations of drug-eluting stents, non-polymeric stents, bioresorbable polymer-coated stents, and fully bioresorbable scaffolds. This review discusses the evolution of coronary stent technology, the efficacy and safety of currently available devices, and the rationale for new generation platforms as efforts continue to design the ideal coronary stent technology. PMID:27627940

  13. Successful technical and clinical outcome using a second generation balloon expandable coronary stent for transplant renal artery stenosis: Our experience

    OpenAIRE

    Salsamendi, Jason; Pereira, Keith; Baker, Reginald; Bhatia, Shivank S; Narayanan, Govindarajan

    2015-01-01

    Transplant renal artery stenosis (TRAS) is a vascular complication frequently seen because of increase in the number of renal transplantations. Early diagnosis and management is essential to optimize a proper graft function. Currently, the endovascular treatment of TRAS using angioplasty and/or stenting is considered the treatment of choice with the advantage that it does not preclude subsequent surgical correction. Treatment of TRAS with the use of stents, particularly in tortuous transplant...

  14. Comparison of Immediate and 2-Year Outcomes between Excimer Laser-Assisted Angioplasty with Spot Stent and Primary Stenting in Intermediate to Long Femoropopliteal Disease

    Directory of Open Access Journals (Sweden)

    Tien-Yu Wu

    2013-01-01

    Full Text Available Background. To compare the clinical outcomes between excimer laser-assisted angioplasty (ELA with spot stent (group A and primary stenting (group B in intermediate to long femoropopliteal disease. Methods. Outcomes of 105 patients totaling 119 legs treated with two different strategies were analyzed retrospectively in a prospectively maintained database. Results. Baseline characteristics were similar in both groups. Better angiographic results and lesser increase of serum C-reactive protein levels (0.60 ± 0.72 versus 2.98 ± 0.97 mg/dL, P<0.001 after the intervention were obtained in Group B. Group A had inferior 1-year outcomes due to higher rate of binary restenosis (67% versus 32%, P=0.001 and lower rate of primary patency (40% versus 58%, P=0.039. Rates of amputation-free survival, target vessel revascularization, assisted primary patency, and stent fracture at 24 months were similar in both groups (80% versus 82%, P=0.979, 65% versus 45%, P=0.11, 78% versus 80%, P=0.75 and 6.3% versus 6.8%, P=0.71, resp.. Conclusion. Greater vascular inflammation after ELA with spot stent resulted in earlier restenosis and inferior 1-year clinical outcomes than primary stenting. This benefit was lost in the primary stenting group at 2 years due to late catch-up restenosis. Active surveillance with prompt intervention was required to maintain the vessel patency.

  15. [Vascular parkinsonism].

    Science.gov (United States)

    Marxreiter, F; Winkler, J

    2016-07-01

    Parkinsonism may result from cerebral vascular disorders that feature white matter lesions and small vessel pathology. Vascular Parkinsonism typically presents as lower body Parkinsonism with predominant gait impairment. Urinary incontinence and cognitive decline are additional features of the disease. There is a considerable overlap between vascular Parkinsonism and vascular dementia. We review the clinical characteristics of vascular Parkinsonism and discuss the current treatment approaches, as well as the role of brain imaging for the diagnostic workup. . PMID:27299942

  16. Current Status of Biliary Metal Stents

    OpenAIRE

    Nam, Hyeong Seok; Kang, Dae Hwan

    2016-01-01

    Many advances have been achieved in biliary stenting over the past 30 years. Endoscopic stent placement has become the primary management therapy to relieve obstruction in patients with benign or malignant biliary tract diseases. Compared with plastic stents, a self-expandable metallic stent (SEMS) has been used for management in patients with malignant strictures because of a larger lumen and longer stent patency. Recently, SEMS has been used for various benign biliary strictures and leaks. ...

  17. Successful endovascular treatment of a hemodialysis graft pseudoaneurysm by covered stent and direct percutaneous thrombin injection.

    LENUS (Irish Health Repository)

    Keeling, Aoife N

    2011-07-25

    Vascular access for hemodialysis remains a challenge for nephrologists, vascular surgeons, and interventional radiologists alike. Arteriovenous fistula and synthetic grafts remain the access of choice for long-term hemodialysis; however, they are subject to complications from infection and repeated needle cannulation. Pseudoaneurysms are an increasingly recognized adverse event. At present, there are many minimally invasive methods to repair these wall defects. We present a graft pseudoaneurysm, which required a combination of endovascular stent graft placement and percutaneous thrombin injection for successful occlusion.

  18. Bioresorbable stent restenosis: new devices, novel situations.

    Science.gov (United States)

    Núñez-Gil, Iván J; Echavarría, Mauro; Escaned, Javier; Biagioni, Corina; Feltes, Gisela; Fernández-Ortiz, Antonio

    2014-12-01

    A 58-year-old man presented to our hospital with effort angina. Ten months prior, he was treated with a Bioresorbable vascular scaffold (BVS). During the current admission, an image angiographically compatible with in-BVS restenosis at the circumflex ostium with a radiolucent image in the ostial left anterior descending artery was shown. BVS failure is very infrequent and this is one of the first cases of BVS restenosis described. Thus, data on the best management option are scarce. We treated it like a drug-eluting stent restenosis, performing first an intracoronary optical coherence tomography scan in order to identify the left descending radiolucent image and to prepare the best treatment strategy. PMID:25480999

  19. Endoscopic Removal of a Proximally Migrated Metal Stent during Balloon Sweeping after Stent Trimming

    OpenAIRE

    Cho, Nam Jun; Lee, Tae Hoon; Park, Sang-Heum; Lee, Han Min; Hyun, Kyung Hee; Lee, Suck-Ho; Chung, Il-Kwun; Kim, Sun-Joo

    2013-01-01

    Placement of a self-expanding metal stent (SEMS) is an effective method for palliation of a malignant biliary obstruction. However, metal stents can cause various complications, including stent migration. Distally migrated metal stents, particularly covered SEMS, can be removed successfully in most cases. Stent trimming using argon plasma coagulation may be helpful in difficult cases despite conventional methods. However, no serious complications related to the trimming or remnant stent remov...

  20. Feasibility study for the investigation of Nitinol self-expanding stents by neutron techniques

    Energy Technology Data Exchange (ETDEWEB)

    Rogante, M., E-mail: main@roganteengineering.i [Rogante Engineering Office, Contrada San Michele n. 61, 62012 Civitanova Marche (Italy); Pasquini, U. [Image and Neuroradiology Deptms, Azienda USL, Emilia-Romagna Region Health Service, 47023 Cesena (Italy); Rosta, L. [Research Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest (Hungary); Lebedev, V. [Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg (Russian Federation)

    2011-02-01

    In this paper, neutron techniques - in particular, small angle neutron scattering (SANS) and neutron diffraction (ND) - are considered for the non-destructive characterization of Nitinol artery stents. This roughly equiatomic (50Ni-50Ti at%) shape memory alloy (SMA) exhibits significant properties of superelasticity and biocompatibility that make it suitable to be typically used as smart material for medical implants and devices. Nitinol self-expanding artery stents, as permanent vascular support structures, supply an ideal option to bypass surgery, but they are submitted for the whole of patient's life to the dynamical stress of the artery pulsation and the aggression from the biological environment. These stents, consequently, can suffer from wear and fracture occurrence likely due to a variety of cyclic fatigue, overload conditions and residual stresses. Neutrons have recently become a progressively more important probe for various materials and components and they allow achieving information complementary to those obtained from the traditional microstructural analyses. The outputs from the preliminary works already carried out in this field consent to consider neutron techniques capable to contribute to the development of these crucial medical implants. The achievable results can yield trends adoptable in monitoring of the stent features. -- Research Highlights: {yields} Neutron techniques can contribute to develop Nitinol self-expanding artery stents. {yields} Neutrons investigations can help avoiding wear and fracture events in Nitinol stents. {yields} Neutron techniques can yield trends adoptable in monitoring of Nitinol stent features. {yields} SANS is able to perform a micro- and nano-scale characterization of Nitinol stents. {yields} Neutron Diffraction helps assessing stresses due to the exercise in Nitinol stents.

  1. Mechanisms of Biliary Plastic Stent Occlusion and Efforts at Prevention

    OpenAIRE

    Kwon, Chang-Il; Lehman, Glen A.

    2016-01-01

    Biliary stenting via endoscopic retrograde cholangiopancreatography has greatly improved the quality of patient care over the last 30 years. Plastic stent occlusion limits the life span of such stents. Attempts to improve plastic stent patency duration have mostly failed. Metal stents (self-expandable metal stents [SEMSs]) have therefore replaced plastic stents, especially for malignant biliary strictures. SEMS are at least 10 times more expensive than plastic stents. In this focused review, ...

  2. Asymmetric Ashes

    Science.gov (United States)

    2006-11-01

    that oscillate in certain directions. Reflection or scattering of light favours certain orientations of the electric and magnetic fields over others. This is why polarising sunglasses can filter out the glint of sunlight reflected off a pond. When light scatters through the expanding debris of a supernova, it retains information about the orientation of the scattering layers. If the supernova is spherically symmetric, all orientations will be present equally and will average out, so there will be no net polarisation. If, however, the gas shell is not round, a slight net polarisation will be imprinted on the light. This is what broad-band polarimetry can accomplish. If additional spectral information is available ('spectro-polarimetry'), one can determine whether the asymmetry is in the continuum light or in some spectral lines. In the case of the Type Ia supernovae, the astronomers found that the continuum polarisation is very small so that the overall shape of the explosion is crudely spherical. But the much larger polarization in strongly blue-shifted spectral lines evidences the presence, in the outer regions, of fast moving clumps with peculiar chemical composition. "Our study reveals that explosions of Type Ia supernovae are really three-dimensional phenomena," says Dietrich Baade. "The outer regions of the blast cloud is asymmetric, with different materials found in 'clumps', while the inner regions are smooth." "This study was possible because polarimetry could unfold its full strength thanks to the light-collecting power of the Very Large Telescope and the very precise calibration of the FORS instrument," he adds. The research team first spotted this asymmetry in 2003, as part of the same observational campaign (ESO PR 23/03 and ESO PR Photo 26/05). The new, more extensive results show that the degree of polarisation and, hence, the asphericity, correlates with the intrinsic brightness of the explosion. The brighter the supernova, the smoother, or less clumpy

  3. Evaluating Stent Optimisation Technique (StentBoost®) in a Dedicated Bifurcation Stent (the Tryton™)

    Energy Technology Data Exchange (ETDEWEB)

    Fysal, Zamil; Hyde, Thomas; Barnes, Edward; McCrea, William; Ramcharitar, Steve, E-mail: steve.ramcharitar@chem.ox.ac.uk

    2014-03-15

    Background/Purpose: To evaluate the use of StentBoost® in the Tryton™ dedicated SideBranch Stent. Methods and Results: The Tryton™ SideBranch Stent has been effectively used to manage complex bifurcations. However, the paucity of scaffolding in the proximal part of the stent makes it often difficult to visualise under standard radiographic imaging. We set out to evaluate whether by using an augmented radiographic imaging technique it was possible to aid visualisation of the stent. In particular the so call 'wedding ring' band which is crucial to the procedural success. We further evaluated whether it was possible to determine the apposition of the stent at the carina, its coverage and the ability to aid recrossing of the struts closest to the carina as well as the added radiation exposure. Conclusions: StentBoost® was found to be invaluable to the procedural success of the Tryton™ deployment without adding any extra cost to the procedure and with only a 3.7% increase in radiation to the patient. It allowed enhanced visualisation in all cases to aid apposition, recrossing and coverage.

  4. A simplified in vivo approach for evaluating the bioabsorbable behavior of candidate stent materials.

    Science.gov (United States)

    Pierson, Daniel; Edick, Jacob; Tauscher, Aaron; Pokorney, Ellen; Bowen, Patrick; Gelbaugh, Jesse; Stinson, Jon; Getty, Heather; Lee, Chee Huei; Drelich, Jaroslaw; Goldman, Jeremy

    2012-01-01

    Metal stents are commonly used to revascularize occluded arteries. A bioabsorbable metal stent that harmlessly erodes away over time may minimize the normal chronic risks associated with permanent implants. However, there is no simple, low-cost method of introducing candidate materials into the arterial environment. Here, we developed a novel experimental model where a biomaterial wire is implanted into a rat artery lumen (simulating bioabsorbable stent blood contact) or artery wall (simulating bioabsorbable stent matrix contact). We use this model to clarify the corrosion mechanism of iron (≥99.5 wt %), which is a candidate bioabsorbable stent material due to its biocompatibility and mechanical strength. We found that iron wire encapsulation within the arterial wall extracellular matrix resulted in substantial biocorrosion by 22 days, with a voluminous corrosion product retained within the vessel wall at 9 months. In contrast, the blood-contacting luminal implant experienced minimal biocorrosion at 9 months. The importance of arterial blood versus arterial wall contact for regulating biocorrosion was confirmed with magnesium wires. We found that magnesium was highly corroded when placed in the arterial wall but was not corroded when exposed to blood in the arterial lumen for 3 weeks. The results demonstrate the capability of the vascular implantation model to conduct rapid in vivo assessments of vascular biomaterial corrosion behavior and to predict long-term biocorrosion behavior from material analyses. The results also highlight the critical role of the arterial environment (blood vs. matrix contact) in directing the corrosion behavior of biodegradable metals.

  5. Endothelial cell repopulation after stenting determines in-stent neointima formation: effects of bare-metal vs. drug-eluting stents and genetic endothelial cell modification.

    OpenAIRE

    Douglas, G; van Kampen, E.; Hale, AB; McNeill, E; Patel, J.; Crabtree, MJ; Ali, Z; Hoerr, RA; Alp, NJ; Channon, KM

    2013-01-01

    Aims Understanding endothelial cell repopulation post-stenting and how this modulates in-stent restenosis is critical to improving arterial healing post-stenting. We used a novel murine stent model to investigate endothelial cell repopulation post-stenting, comparing the response of drug-eluting stents with a primary genetic modification to improve endothelial cell function. Methods and results Endothelial cell repopulation was assessed en face in stented arteries in ApoE−/− mice with end...

  6. Late Pseudocoarctation Syndrome After Stent-Graft Implantation For Traumatic Aortic Rupture

    Energy Technology Data Exchange (ETDEWEB)

    Letocart, Vincent, E-mail: vincent.letocart@chu-nantes.fr; Fau, Georges, E-mail: georges.fau@chu-nantes.fr; Tirouvanziam, Ashok, E-mail: ashok.tirouvanziam@chu-nantes.fr [University Hospital of Nantes, Institut du Thorax (France); Toquet, Claire, E-mail: claire.toquet@chu-nantes.fr [University Hospital of Nantes, Department of Pathology (France); Al Habash, Oussama, E-mail: oussama.alhabash@chu-nantes.fr; Guerin, Patrice, E-mail: patrice.guerin@chu-nantes.fr [University Hospital of Nantes, Institut du Thorax (France); Rousseau, Herve, E-mail: rousseau.h@chu-toulouse.fr [University Hospital of Toulouse, Department of Radiology (France); Crochet, Dominique, E-mail: dominique.crochet@chu-nantes.fr [University Hospital of Nantes, Institut du Thorax (France)

    2013-06-15

    The present observation illustrates an unusual complication occurring after stent-grafting (S-graft) for aortic isthmus rupture. A 22-year-old patient, treated by S-graft in the emergency department for traumatic aortic rupture, was readmitted 10 months later with pseudocoarctation syndrome. A membrane was found inside the stent-graft that had induced a pseudo-dissection, which caused the pseudocoarctation syndrome. Surgical treatment consisted of removing the stent-graft and membrane and replacing it with a vascular implant. The patient's clinical course was fair. The suggested mechanism was circumferential neoendothelialization of the stent-graft. Dehiscence caused the superior part of the membrane to drop into the lumen of the stent-graft creating a 'false channel' that compressed the 'true lumen' and induced 'pseudocoarctation' syndrome. The cause of the extensive neointimalization remains unexplained. Thoracic aortic stent-grafts require regular follow-up monitoring by angioscan or angio-magnetic resonance imaging.

  7. Computational fluid dynamics evaluation of incomplete stent apposition in a tapered artery

    Science.gov (United States)

    Poon, Eric; Thondapu, Vikas; Ooi, Andrew; Hayat, Umair; Barlis, Peter; Moore, Stephen

    2015-11-01

    Coronary stents are deployed to prop open blocked arteries and restore normal blood flow, however in-stent restenosis (ISR) and stent thrombosis (ST) remain possibly catastrophic complications. Computational fluid dynamics (CFD) analyses can elucidate the pathological impact of alterations in coronary hemodynamics and correlate wall shear stress (WSS) with atherosclerotic processes. The natural tapering of a coronary artery often leads to proximal incomplete stent apposition (ISA) where stent struts are not in contact with the vessel wall. By employing state-of-the-art computer-aided design (CAD) software, generic open-cell and closed-cell coronary stent designs were virtually deployed in an idealised tapered coronary artery. Pulsatile blood flow (80 mL/min at 75 beats/min) was carried out numerically on these CAD models using a finite volume solver. CFD results reveal significant fluctuations in proximal WSS and large recirculation regions in the setting of proximal ISA, resulting in regions of high wall shear stress gradient (WSSG) that have been previously linked to poor endothelial cell coverage and vascular injury. The clinical significance of these proximal high WSSG regions will be correlated with findings from high-resolution in-vivo imaging. Supported by the Australian Research Council (LP120100233) and Victorian Life Sciences Computation Initiative (VR0210).

  8. Everolimus-eluting bioresorbable stent vs. durable polymer everolimus-eluting metallic stent in patients with ST-segment elevation myocardial infarction

    DEFF Research Database (Denmark)

    Sabaté, Manel; Windecker, Stephan; Iñiguez, Andres;

    2015-01-01

    AIMS: Patients with ST-segment elevation myocardial infarction (STEMI) feature thrombus-rich lesions with large necrotic core, which are usually associated with delayed arterial healing and impaired stent-related outcomes. The use of bioresorbable vascular scaffolds (Absorb) has the potential...... to overcome these limitations owing to restoration of native vessel lumen and physiology at long term. The purpose of this randomized trial was to compare the arterial healing response at short term, as a surrogate for safety and efficacy, between the Absorb and the metallic everolimus-eluting stent (EES...... was the 6-month optical frequency domain imaging healing score (HS) based on the presence of uncovered and/or malapposed stent struts and intraluminal filling defects. Main secondary endpoint included the device-oriented composite endpoint (DOCE) according to the Academic Research Consortium definition...

  9. Metallic stent placement in hemodialysis graft patients after insufficient balloon dilation

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Huei-Lung; Pan, Huay-Ben; Lin, Yih-Huie; Chen, Chiung-Yu; Lai, Pin-Hong; Yang, Chien-Fang [Kaohsiung Veterans General Hospital, Kaohsiung (China); Chung, Hsiao-Min; Wu, Tung-Ho; Chou, Kang-Ju [National Yangming University, Taipei (China)

    2006-06-15

    We wanted to report our experience of metallic stent placement after insufficient balloon dilation in graft hemodialysis patients. Twenty-three patients (13 loop grafts in the forearm and 10 straight grafts in the upper arm) underwent metallic stent placement due to insufficient flow after urokinase thrombolysis and balloon dilation. The indications for metallic stent deployment included 1) recoil and/or kinked venous stenosis in 21 patents (venous anastomosis: 17 patients, peripheral outflow vein: four patients); and 2) major vascular rupture in two patients. Metallic stents 8-10mm in diameter and 40-80 mm in length were used. Of them, eight stents were deployed across the elbow crease. Access patency was determined by clinical follow-up and the overall rates were calculated by Kaplan-Meier survival analysis. No procedure-related complications (stent fracture or central migration) were encountered except for a delayed Wallstent shortening/migration at the venous anastomosis, which resulted in early access failure. The overall primary and secondary patency rates ({+-}standard error) of all the vascular accesses in our 23 patients at 3, 6, 12 and 24 months were 69%{+-}9 and 88%{+-}6,41% {+-}10 and 88%{+-}6, 30%{+-}10 and 77%{+-}10, and 12%{+-}8 and 61%{+-}13, respectively. For the forearm and upper-arm grafts, the primary and secondary patency rates were 51%{+-}16 and 86%{+-}13 vs 45%{+-}15 and 73%{+-}13 at 6 months, and 25%{+-}15 and 71%{+-}17 vs 23%{+-}17 and 73%{+-}13 at 12 months ({rho} = .436 and .224), respectively. Metallic stent placement is a safe and effective means for treating peripheral venous lesions in dialysis graft patients after insufficient balloon dilation. No statistically difference in the patency rates between the forearm and upper-arm patient groups was seen.

  10. Percutaneous cholangioscopy in obstructed biliary metal stents

    International Nuclear Information System (INIS)

    Purpose. To reevaluate the reasons for the occlusion of self-expanding biliary metal stents, on the basis of cholangioscopic findings. Methods. Percutaneous transhepatic cholangioscopy (PTCS) was performed in 15 patients with obstructed biliary Wallstents. The reason for stent insertion was a malignant obstruction in 14 patients; 1 had a benign biliary stricture. Conventional noncovered stents had been inserted in 12 patients; in 3 cases a polyurethane-covered prototype Wallstent had been used. Stent occlusions occurred after 1-55 months. PTCS was performed with a 2.3-mm endoscope through an 11 Fr sheath. Biopsies were taken via the working channel of the endoscope. Results. In all patients with noncovered stents the inner surface of the stent was highly irregular with seaweed-like protrusions (biopsy-proven granulation tissue). Stent incorporation varied from absent (n=1) to subtotal (n=8), but was always incomplete, no matter how long the stent had been in place. Tumor ingrowth was histologically proven in 2 patients. One patient had a large occluding concrement at the proximal end of the stent. In patients with covered stents, the inner surface appeared more regular; however, viable granulation tissue was found inside two stents and tumor ingrowth in one of them. Conclusion. PTCS showed that incorporation of the stent is virtually always incomplete. The factors contributing most to stent occlusion are the buildup of granulation tissue, bile sludge, and tumor overgrowth. Stone formation and tumor ingrowth can also be important, although less common causes of occlusion. A polyurethane stent covering could not prevent tumor ingrowth in one patient and the buildup of viable granulation tissue inside the stent in two further patients; mean stent patency in the three patients with such a stent was 3 months

  11. Coronary aneurysm and very late stent thrombosis formation associated with sirolimus-eluting stent implantation

    Institute of Scientific and Technical Information of China (English)

    XIE Hong-zhi; ZHANG Shu-yang; ZENG Yong; SHEN Zhu-jun; FANG Quan

    2009-01-01

    @@ Since drug-eluting stents (DES) can significantly reduce the risk of instant restenosis compared with bare-metal stents, they have been widely used in interventional therapy for coronary heart disease. With bare-metal stents being rapidly replaced by DES there is a great concern about the safety of DES due to stent thrombosis.~(1,2)

  12. Drug-eluting stents and bare metal stents in patients with NSTE-ACS

    DEFF Research Database (Denmark)

    Pedersen, Sune Haahr; Pfisterer, Matthias; Kaiser, Christoph;

    2014-01-01

    the randomised BASKET-PROVE trial (sirolimus-eluting stent vs. everolimus-eluting stent vs. bare metal stent in large-vessel stenting). The primary endpoint was the combined two-year rate of cardiovascular death or non-fatal myocardial infarction (MI). Secondary endpoints were each component of the primary...

  13. COMBINED INTRAOPERATIVE ILIAC ARTERY STENTS AND FEMORO-POPLITEAL BYPASS FOR MULTILEVEL ATHEROSCLEROTIC OCCLUSIVE DISEASE

    Institute of Scientific and Technical Information of China (English)

    刘昌伟; 管珩; 李拥军; 郑曰宏; 刘卫

    2001-01-01

    Objective. To review our preliminary experience and evaluate our early results of a combined intraoperative iliac angioplasty and stenting with infrainguinal revascularization in multilevel atherosclerotic occlusive disease.``Methods. From July 1999 to April 2000, intraoperative iliac angioplasty and stenting combined with simultaneous femoro-popliteal bypass were performed on 12 lower extremities of 10 patients suffering from multilevel atherosclerotic occlusive disease. There were 8 men and 2 women, average 72 years. The indications for procedures included disabling claudication in 3 and rest pain in 7 patients.``Results. Eleven iliac angioplasty and stent procedures combined with simultaneous 9 femoro-popliteal bypass and 3 femoro-femoral-popliteal bypass were performed in 12 limbs of 10 patients. Angioplasty and stent placement was technically successful in all patients. One contralateral femoral-popliteal bypass was failure after femorofemoral-popliteal bypass. There were no additional instances of procedural or postoperative morbidity or mortality. Mean follow-up was 5 months (range 1 ~ 10 months). During the follow-up period, one femoro-infrapoplitealgraft became occluded after 7 months and above-knee amputation was required. The cumulative primary patency rate of stented iliac arteries, femoro-femoral bypass grafts and femoro-popliteal bypass grafts were 100% ( 11 /11), 100% (3/3) and 90. 9% (10/11) in the follow-up period, respectively. The amputation rate was 8.3%(1/12).``Conclusions. Intraoperative iliac artery PTA and stent placement can be safely and effectively performed simultaneously with infrainguinal revascularization for multilevel atherosclerotic occlusive disease by skilled vascular surgeon, using a prtable C arm fluoroscopy in the operating room. Furthermore, iliac artery PTA and stenting was valuable adjunct to distal bypass either to improve inflow and outflow, or to reduce the extent of traditional surgical intervention, and also, any

  14. Very late coronary aneurysm formation with subsequent stent thrombosis secondary to drug-eluting stent

    Institute of Scientific and Technical Information of China (English)

    Ibrahim Akin,; Stephan Kische; Tim C Rehders; Henrik Schneider; G(o)kmen R Turan; Tilo Kleinfeldt; Jasmin Ortak; Christoph A. Nienaber; Hüseyin Ince

    2011-01-01

    Drug-eluting stents have changed the practice in interventional cardiology.With the widespread use of these stents important safety concerns regarding stent thrombosis and formation of coronary artery aneurysm have been expressed.While the majority of attention was focused on stent thrombosis,the formation of coronary aneurysm was only described in anecdotal reports.We report on a patient who suffered from very late stent thrombosis in association with coronary artery aneurysm formation secondary to drug-eluting stent but not to bare-metal stent.

  15. Mechanisms of Biliary Plastic Stent Occlusion and Efforts at Prevention.

    Science.gov (United States)

    Kwon, Chang-Il; Lehman, Glen A

    2016-03-01

    Biliary stenting via endoscopic retrograde cholangiopancreatography has greatly improved the quality of patient care over the last 30 years. Plastic stent occlusion limits the life span of such stents. Attempts to improve plastic stent patency duration have mostly failed. Metal stents (self-expandable metal stents [SEMSs]) have therefore replaced plastic stents, especially for malignant biliary strictures. SEMS are at least 10 times more expensive than plastic stents. In this focused review, we will discuss basic mechanisms of plastic stent occlusion, along with a systematic summary of previous efforts and related studies to improve stent patency and potential new techniques to overcome existing limitations. PMID:27000422

  16. Misplacement or migration? Extremely rare case of cardiac migration of a ureteral j stent.

    Science.gov (United States)

    Kim, Tae Nam; Lee, Chan Ho; Kong, Do Hoon; Shin, Dong Kil; Lee, Jeong Zoo

    2014-05-01

    A 29-year-old woman with mild back pain when coughing and suprapubic discomfort after voiding was admitted to Pusan National University Hospital. Two weeks earlier, she had undergone a hysterectomy and right-sided ureteroneocystostomy for uterine atony and right ureteral injury with bladder rupture. Computed tomography showed that a ureteral J stent extended from the right ovarian vein to the right cardiac chamber. The stent was retrieved via both femoral veins with a snare loop and pigtail catheter. Computed tomography showed that the urinary and vascular tracts were normal 5 months after the procedure. PMID:24868342

  17. Endovascular covered stent repair of an iatrogenic subclavian artery-to-pulmonary artery fistula and pseudoaneurysm.

    Science.gov (United States)

    Wheeler, Shane C; Zinn, Kenneth M; Hughes, Terence W

    2007-06-01

    An iatrogenic fistula and consequent pseudoaneurysm developed between the right subclavian artery and right pulmonary artery as a result of misplacement of a hemodialysis access catheter. The patient, who was considered to be at high risk for surgical repair, successfully underwent endovascular treatment that involved insertion of two nitinol stents covered with expanded polytetrafluoroethylene (stent-grafts), one into the right subclavian artery and the other into a right upper lobe pulmonary artery. Multi-detector row computed tomographic angiography played an integral role in the evaluation of the patient's vascular injury and treatment planning. PMID:17538141

  18. CT in vascular pathologies

    Energy Technology Data Exchange (ETDEWEB)

    Bartolozzi, C.; Neri, E.; Caramella, D. [Diagnostic and Interventional Radiology Department of Oncology, University of Pisa, Via Roma 67, I-56100 Pisa (Italy)

    1998-06-02

    Since the introduction of helical scanners, CT angiography (CTA) has achieved an essential role in many vascular applications that were previously managed with conventional angiography. The performance of CTA is based on the accurate selection of collimation width, pitch, reconstruction spacing and scan delay, which must be modulated on the basis of the clinical issue. However, the major improvement of CT has been provided by the recent implementation of many post-processing techniques, such as multiplanar reformatting, shaded surface display, maximum intensity projections, 3D perspectives of surface and volume rendering, which simulate virtual intravascular endoscopy. The integration of the potentialities of the scanner and of the image processing techniques permitted improvement of: (a) the evaluation of aneurysms, dissection and vascular anomalies involving the thoracic aorta; (b) carotid artery stenosis; (c) aneurysms of abdominal aorta; (d) renal artery stenosis; (e) follow-up of renal artery stenting; and (f) acute or chronic pulmonary embolism. Our experience has shown that the assessment of arterial pathologies with CTA requires the integration of 3D post-processing techniques in most applications. (orig.) With 4 figs., 34 refs.

  19. Preventive role of palladium-103 radioactive stent on in-stent restenosis in rabbit iliac arteries

    Institute of Scientific and Technical Information of China (English)

    LUO Quan-Yong; CHEN Li-Bo; YUAN Zhi-Bin; LU Han-Kui; ZHU Rui-Sen

    2005-01-01

    The abilility of γ-emitting palladium-103 stent implantation to inhibit in-stent restenosis in rabbit iliac arteries was investigated. Quantitative histomorphometry of the stented iliac segments 28 days after the implantation indicated that palladium-103 stents made a significant reduction in neointimal area and percent area stenosis compared with the nonradioactive stents. Lumen area in the palladium-103 stents treatment group was larger than the control group. However, the reduction of neointima formation by palladium-103 stents implantation was in a non-dose-dependent fashion. Low ionizing radiation doses via γ-emitting palladiurn-103 stent are effective in preventing neointimal hyperplasia in iliac arteries of rabbits. Palladium-103 stents can be employed as a possible novel means to prevent in-stent restenosis.

  20. Angioplasty and stent placement - carotid artery

    Science.gov (United States)

    Carotid angioplasty and stenting; CAS; Angioplasty - carotid artery; Carotid artery stenosis - angioplasty; ... Carotid angioplasty and stenting (CAS) is done using a small surgical cut. Your surgeon will make a surgical cut ...

  1. Acute stent recoil in the left main coronary artery treated with additional stenting.

    Science.gov (United States)

    Battikh, Kais; Rihani, Riadh; Lemahieu, Jean Michel

    2003-01-01

    We report a case of acute stent recoil occurring after the stenting of an ostial left main coronary artery lesion. The marked recoil after high-pressure balloon inflation confirmed that the radial force of the first stent was unable to ensure vessel patency. The addition of a second stent provided the necessary support to achieve a good final result. This case illustrates a possible complication of aorto-ostial angioplasty that could be treated with double stenting. PMID:12499528

  2. Extracellular Matrix Molecules Facilitating Vascular Biointegration

    Directory of Open Access Journals (Sweden)

    Martin K.C. Ng

    2012-08-01

    Full Text Available All vascular implants, including stents, heart valves and graft materials exhibit suboptimal biocompatibility that significantly reduces their clinical efficacy. A range of biomolecules in the subendothelial space have been shown to play critical roles in local regulation of thrombosis, endothelial growth and smooth muscle cell proliferation, making these attractive candidates for modulation of vascular device biointegration. However, classically used biomaterial coatings, such as fibronectin and laminin, modulate only one of these components; enhancing endothelial cell attachment, but also activating platelets and triggering thrombosis. This review examines a subset of extracellular matrix molecules that have demonstrated multi-faceted vascular compatibility and accordingly are promising candidates to improve the biointegration of vascular biomaterials.

  3. Coronary Angioplasty Stent Placement

    Medline Plus

    Full Text Available ... so. I think the main vascular and the life threatening, immediate life threatening causes of chest pain I think have ... done. And once we commit people to a life-long therapy with very potent blood thinners, that ...

  4. Visualization of stent lumen in MR imaging. Relationship with stent design and RF direction

    International Nuclear Information System (INIS)

    Magnetic resonance imaging (MRI) visualization of metallic stent lumens is possible if the stent structure counteracts eddy currents in the lumen induced by the radio frequency magnetic field, B1. To examine the effectiveness of various stent designs in counteracting eddy currents, we anchored eight copper stent models and 2 commercially available nickel-titanium alloy (Nitinol) stents in a gel phantom, perpendicular or parallel to the direction of B1. A mesh stent lumen showed hypointensity irrespective of its alignment relative to B1. A solenoid stent lumen showed hypointensity with the stent axis parallel to B1, but it had the same signal intensity as outside the lumen when perpendicular to B1. A Moebius stent lumen showed no signal reduction, irrespective of alignment relative to B1. Lumens of the commercially available stents showed hypointensity regardless of alignment relative to B1. Computer simulation revealed that the signal intensities of the stents corresponded to magnetic flux densities of B1 in the stents, which are modified by the structure of the stent. While in vivo MRI viewing of a Moebius stent lumen is likely possible regardless of axis alignment, inherent structural weakness may be problematic. As a more practical choice, the solenoid stent is easier to manufacture and generates no hypointensive signal when the axis is parallel to B0. (author)

  5. 21 CFR 884.3900 - Vaginal stent.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Vaginal stent. 884.3900 Section 884.3900 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES... stent. (a) Identification. A vaginal stent is a device used to enlarge the vagina by stretching, or...

  6. Incidence and predictors of coronary stent thrombosis

    DEFF Research Database (Denmark)

    D'Ascenzo, Fabrizio; Bollati, Mario; Clementi, Fabrizio;

    2013-01-01

    Stent thrombosis remains among the most feared complications of percutaneous coronary intervention (PCI) with stenting. However, data on its incidence and predictors are sparse and conflicting. We thus aimed to perform a collaborative systematic review on incidence and predictors of stent...... thrombosis....

  7. New stent design for use in small coronary arteries during percutaneous coronary intervention

    Directory of Open Access Journals (Sweden)

    Juan F Granada

    2010-10-01

    Full Text Available Juan F Granada1, Barbara A Huibregtse2, Keith D Dawkins21The Jack H Skirball Center for Cardiovascular Research, Cardiovascular Research Foundation, Columbia University Medical Center, New York, NY, USA; 2Boston Scientific Corporation, Natick, MA, USAAbstract: Patients with diabetes mellitus, of female gender, increased age, and/or with peripheral vascular disease often develop coronary stenoses in small caliber vessels. This review describes treatment of these lesions with the paclitaxel-eluting 2.25 mm TAXUS® Liberté® Atom™ stent. Given the same stent composition, polymer, antirestenotic drug (paclitaxel, and release kinetics as the first-generation 2.25 mm TAXUS® Express® Atom™ stent, the second-generation TAXUS Liberté Atom stent incorporates improved stent design characteristics, including thinner struts (0.0038 versus 0.0052 inches, intended to increase conformability and deliverability. In a porcine noninjured coronary artery model, TAXUS Liberté Atom stent implantation in small vessels demonstrated complete strut tissue coverage compared with the bare metal stent control, suggesting a similar degree of tissue healing between the groups at 30, 90, and 180 days. The prospective, single-armed TAXUS ATLAS Small Vessel trial demonstrated improved instent late loss (0.28 ± 0.45 versus 0.84 ± 0.57 mm, P < 0.001, instent binary restenosis (13.0% versus 38.1%, P < 0.001, and target lesion revascularization (5.8% versus 17.6%, P < 0.001 at nine months with the TAXUS Liberté Atom stent as compared with the bare metal Express stent control, with similar safety measures between the two groups. The TAXUS Liberté Atom also significantly reduced nine-month angiographic rates of both instent late loss (0.28 ± 0.45 versus 0.44 ± 0.61 mm, P = 0.03 and instent binary restenosis (13.0% versus 25.9%, P = 0.02 when compared with the 2.25 mm TAXUS Express Atom control. The observed reduction in target lesion revascularization with the TAXUS

  8. Geometrical deployment for braided stent.

    Science.gov (United States)

    Bouillot, Pierre; Brina, Olivier; Ouared, Rafik; Yilmaz, Hasan; Farhat, Mohamed; Erceg, Gorislav; Lovblad, Karl-Olof; Vargas, Maria Isabel; Kulcsar, Zsolt; Pereira, Vitor Mendes

    2016-05-01

    The prediction of flow diverter stent (FDS) implantation for the treatment of intracranial aneurysms (IAs) is being increasingly required for hemodynamic simulations and procedural planning. In this paper, a deployment model was developed based on geometrical properties of braided stents. The proposed mathematical description is first applied on idealized toroidal vessels demonstrating the stent shortening in curved vessels. It is subsequently generalized to patient specific vasculature predicting the position of the filaments along with the length and local porosity of the stent. In parallel, in-vitro and in-vivo FDS deployments were measured by contrast-enhanced cone beam CT (CBCT) in idealized and patient-specific geometries. These measurements showed a very good qualitative and quantitative agreement with the virtual deployments and provided experimental validations of the underlying geometrical assumptions. In particular, they highlighted the importance of the stent radius assessment in the accuracy of the deployment prediction. Thanks to its low computational cost, the proposed model is potentially implementable in clinical practice providing critical information for patient safety and treatment outcome assessment. PMID:26891065

  9. Early outcomes after carotid angioplasty with stenting performed by neurologists

    Directory of Open Access Journals (Sweden)

    Bathala Lokesh

    2010-01-01

    Full Text Available Aims: To evaluate the results of carotid artery angioplasty and stenting (CAS in treating extracranial carotid artery stenosis performed by neurologists in our center and compare the results with other large published series. Materials and Methods: Data for all patients who underwent CAS from January 2003 through November 2007, was retrieved from the Nanjing Stroke Registry. Perioperative and post-procedural complications within 30 days following stenting were analyzed and compared with that from other series. A total number of 75 patients were enrolled, with a mean age of 65.9 ± 8.8 years, and 64 (85.3% of them were male. Results: Procedural success was achieved in 74 patients (98.7%. Pre-treatment stenosis was 73.8 ± 14.9 and post-treatment residual stenosis was less than 10%. Thirty-four patients (45.3% had bilateral carotid artery disease and seven (9.3% had tandem stenosis. The neurological complication rate was 3.9% (one major and two minor strokes. Bradycardia in four (5.3% and hypotension in 13 (17.3% were observed during procedures. Using the Fischer′s exact t test, the complication rate compared with the large published series did not reveal any statistically significant difference (P > 0.05. Conclusions: We conclude that neurologists, with adequate training, can develop and add this technical skill to the existing cognitive skill of vascular neurology and safely perform stenting.

  10. David M. Hume Memorial Lecture. Impact of endovascular technology on the practice of vascular surgery.

    Science.gov (United States)

    Veith, F J; Marin, M L

    1996-08-01

    Endovascular treatment techniques have already replaced some vascular operations. The likelihood is that new endovascular techniques involving stents and stented grafts will replace additional vascular operations. All these treatments involve the use of catheter-guidewire, balloon, and imaging modalities, particularly digital fluoroscopy. These modalities have already and will increasingly help to improve and simplify standard vascular operations such as thromboembolectomy, infrainguinal bypasses, and management of aneurysms and arteriovenous fistulas. Accordingly, vascular surgeons must become familiar with and use these endovascular methods and techniques. This can be accomplished in a variety of ways which includes working as part of a multidisciplinary vascular treatment group in which various specialists collaborate to provide the best, most cost-effective care to vascular disease patients.

  11. Extremities--indications and techniques for treatment of extremity vascular injuries.

    Science.gov (United States)

    Doody, O; Given, M F; Lyon, S M

    2008-11-01

    Traumatic vascular injuries involving the extremity are rare and penetrating trauma accounts for the majority of such injuries. The remaining arterial injuries are as a result of either blunt or iatrogenic injuries. The rapid detection, localisation and characterisation of vascular injuries in patients who have a traumatic extremity injury is essential for the effective management and treatment of such injuries. This review will discuss the expanding role of multi-detector computed tomography angiography in diagnosing vascular injuries and its implications on conventional diagnostic angiography. The roles of other non-invasive imaging modalities are reviewed. The presentation and types of vascular injuries in blunt and penetrating injuries are discussed. While surgery remains the gold standard in the management of vascular extremity injuries it has significant morbidity rates. Endovascular techniques are increasingly being used for the treatment of vascular traumatic injuries and various techniques including balloon occlusion, embolisation and stent/stent graft placement are discussed. PMID:18845300

  12. 阿折地平对西罗莫司洗脱支架致血管内皮损伤的干预作用及机制探讨%Protective effect of azelnidipine on sirolimus eluting stent-induced vascular endothelial injury and its mechanism

    Institute of Scientific and Technical Information of China (English)

    袁玲; 聂卫; 高萍; 李昕; 刘伟伟; 崔晓雪

    2015-01-01

    Objective To investigate the protective effect of calcium-channel blockers azelnidipine on sirolimus elu-ting stent-induced vascular endothelial injury and its mechanism .Methods Human umbilical vein endothelial cells ( HU-VECs) were cultivated and divided into the control group (treated with culture medium), model group (treated with siroli-mus 500 nmol/L) and the experimental group (azelnidipine 10 μmol/L +sirolimus 500 nmol/L), respectively.After 24 h of treatment, changes in cell morphology were observed by HE staining .Effects on the production of nitric oxide (NO) were detected by Nitric Oxide Assay Kit .The intracellular calcium ion ( Ca2+) concentration was assayed with Fluo-3/AM staining, the changes of mitochondrial membrane potential was detected by JC -1 fluorescence labeling , and the apoptosis rate of HUVECs was analyzed by Annexin V FITC/PI staining.Results After 24 h of treatment, in the control group, cells were polygonal and in the single cobblestone arrangement;in the model group, cell swelled, cytoplasm had vacuoles, part of the nucleus had pycnosis , and nuclear fragmentation were observed;in the experimental group , cells were substan-tially polygonal , and in the single cobblestone arrangement , the cell swelling and cytoplasmic vacuoles were rare .Com-pared with the control group , the levels of NO in the cell culture fluid were reduced , the levels of intracellular free Ca 2+were increased , apoptosis rate was increased and mitochondrial membrane potential was reduced in the model group and ex -perimental group (all P<0.05).Compared with the model group, the levels of NO in the cell culture fluid were in-creased , the levels of intracellular free Ca 2+were reduced , the apoptosis rate was reduced and the mitochondrial membrane potential was increased in the experimental group (all P<0.05).Conclusions Azelnidipine has protective effect on sirolimus eluting stent-induced vascular endothelial injury .The possible mechanism might be related to

  13. Computational replication of the patient-specific stenting procedure for coronary artery bifurcations: From OCT and CT imaging to structural and hemodynamics analyses.

    Science.gov (United States)

    Chiastra, Claudio; Wu, Wei; Dickerhoff, Benjamin; Aleiou, Ali; Dubini, Gabriele; Otake, Hiromasa; Migliavacca, Francesco; LaDisa, John F

    2016-07-26

    The optimal stenting technique for coronary artery bifurcations is still debated. With additional advances computational simulations can soon be used to compare stent designs or strategies based on verified structural and hemodynamics results in order to identify the optimal solution for each individual's anatomy. In this study, patient-specific simulations of stent deployment were performed for 2 cases to replicate the complete procedure conducted by interventional cardiologists. Subsequent computational fluid dynamics (CFD) analyses were conducted to quantify hemodynamic quantities linked to restenosis. Patient-specific pre-operative models of coronary bifurcations were reconstructed from CT angiography and optical coherence tomography (OCT). Plaque location and composition were estimated from OCT and assigned to models, and structural simulations were performed in Abaqus. Artery geometries after virtual stent expansion of Xience Prime or Nobori stents created in SolidWorks were compared to post-operative geometry from OCT and CT before being extracted and used for CFD simulations in SimVascular. Inflow boundary conditions based on body surface area, and downstream vascular resistances and capacitances were applied at branches to mimic physiology. Artery geometries obtained after virtual expansion were in good agreement with those reconstructed from patient images. Quantitative comparison of the distance between reconstructed and post-stent geometries revealed a maximum difference in area of 20.4%. Adverse indices of wall shear stress were more pronounced for thicker Nobori stents in both patients. These findings verify structural analyses of stent expansion, introduce a workflow to combine software packages for solid and fluid mechanics analysis, and underscore important stent design features from prior idealized studies. The proposed approach may ultimately be useful in determining an optimal choice of stent and position for each patient. PMID:26655589

  14. Computational replication of the patient-specific stenting procedure for coronary artery bifurcations: From OCT and CT imaging to structural and hemodynamics analyses.

    Science.gov (United States)

    Chiastra, Claudio; Wu, Wei; Dickerhoff, Benjamin; Aleiou, Ali; Dubini, Gabriele; Otake, Hiromasa; Migliavacca, Francesco; LaDisa, John F

    2016-07-26

    The optimal stenting technique for coronary artery bifurcations is still debated. With additional advances computational simulations can soon be used to compare stent designs or strategies based on verified structural and hemodynamics results in order to identify the optimal solution for each individual's anatomy. In this study, patient-specific simulations of stent deployment were performed for 2 cases to replicate the complete procedure conducted by interventional cardiologists. Subsequent computational fluid dynamics (CFD) analyses were conducted to quantify hemodynamic quantities linked to restenosis. Patient-specific pre-operative models of coronary bifurcations were reconstructed from CT angiography and optical coherence tomography (OCT). Plaque location and composition were estimated from OCT and assigned to models, and structural simulations were performed in Abaqus. Artery geometries after virtual stent expansion of Xience Prime or Nobori stents created in SolidWorks were compared to post-operative geometry from OCT and CT before being extracted and used for CFD simulations in SimVascular. Inflow boundary conditions based on body surface area, and downstream vascular resistances and capacitances were applied at branches to mimic physiology. Artery geometries obtained after virtual expansion were in good agreement with those reconstructed from patient images. Quantitative comparison of the distance between reconstructed and post-stent geometries revealed a maximum difference in area of 20.4%. Adverse indices of wall shear stress were more pronounced for thicker Nobori stents in both patients. These findings verify structural analyses of stent expansion, introduce a workflow to combine software packages for solid and fluid mechanics analysis, and underscore important stent design features from prior idealized studies. The proposed approach may ultimately be useful in determining an optimal choice of stent and position for each patient.

  15. Configuration-space technique for calculating stent-fitness measures for the planning of neuro-endovascular interventions

    Science.gov (United States)

    Kesavadas, Thenkurussi; Agrawal, Rajendra; Hoffmann, Kenneth R.

    2005-04-01

    This paper demonstrates a new technique to compute stent-fitness measures for a vascular anatomy, using geometric information. This technique will aid the interventionalist in treatment planning for Neuro-endovascular interventions. Patient-specific vessel-surface reconstruction is performed from point/contour data without user intervention. The technique developed is based on configuration-space algorithms, which are widely used in robot motion planning. A fitness measure is computed for stents with various parameters for a patient-specific vessel data. Finally, a simulation is performed to check for collisions. This feature will provide an additional tool to the interventionalist for the planning of neuro-endovascular interventions, with the dimensions of the stent based on proximal and distal neck of the aneurysm for a patient-specific vascular anatomy.

  16. "Virtual" in-vivo bench test for bifurcation stenting with "StentBoost".

    Science.gov (United States)

    Agostoni, Pierfrancesco; Verheye, Stefan; Vermeersch, Paul; Cornelis, Kristoff; Van Langenhove, Glenn

    2009-04-01

    "StentBoost" is a new angiographic technique that allows improved angiographic visualization of stents deployed in coronary arteries, by enhancing the X-ray focus of the region where the stent is placed. Using this technique we were able to assess the deformation and the expansion of a stent deployed to treat a bifurcation lesion between the mid-left anterior descending (LAD) artery and a big second diagonal branch, during sequential inflations of: (1) the stent per se in the LAD, (2) the ostium of the diagonal branch through the stent struts, (3) the stent again with a non compliant balloon, and (4) both branches with the kissing balloon technique. "StentBoost" guided our clinical and angiographic decision-making process and allowed us to create a "virtual" bench test of the stent deployed at the level of the bifurcation treated.

  17. [Vascular dementia

    NARCIS (Netherlands)

    Leeuw, H.F. de; Gijn, J. van

    2004-01-01

    Vascular dementia is one of the most frequently occurring dementia syndromes. Its prevalence is about 5% among subjects above 85 years of age. Elevated blood pressure and atherosclerosis are the most important risk factors. According to international criteria, vascular dementia usually occurs within

  18. Current Status of Biliary Metal Stents.

    Science.gov (United States)

    Nam, Hyeong Seok; Kang, Dae Hwan

    2016-03-01

    Many advances have been achieved in biliary stenting over the past 30 years. Endoscopic stent placement has become the primary management therapy to relieve obstruction in patients with benign or malignant biliary tract diseases. Compared with plastic stents, a self-expandable metallic stent (SEMS) has been used for management in patients with malignant strictures because of a larger lumen and longer stent patency. Recently, SEMS has been used for various benign biliary strictures and leaks. In this article, we briefly review the characteristics of SEMS as well as complications of stent placement. We review the current guidelines for managing malignant and benign biliary obstructions. Recent developments in biliary stenting are also discussed. PMID:26911896

  19. Recent Advances of Biliary Stent Management

    International Nuclear Information System (INIS)

    Recent progress in chemotherapy has prolonged the survival of patients with malignant biliary strictures, leading to increased rates of stent occlusion. Even we employed metallic stents which contributed to higher rates and longer durations of patency, and occlusion of covered metallic stents now occurs in about half of all patients during their survival. We investigated the complication and patency rate for the removal of covered metallic stents, and found that the durations were similar for initial stent placement and re-intervention. In order to preserve patient quality of life, we currently recommend the use of covered metallic stents for patients with malignant biliary obstruction because of their removability and longest patency duration, even though uncovered metallic stents have similar patency durations.

  20. Current Status of Biliary Metal Stents

    Science.gov (United States)

    Nam, Hyeong Seok; Kang, Dae Hwan

    2016-01-01

    Many advances have been achieved in biliary stenting over the past 30 years. Endoscopic stent placement has become the primary management therapy to relieve obstruction in patients with benign or malignant biliary tract diseases. Compared with plastic stents, a self-expandable metallic stent (SEMS) has been used for management in patients with malignant strictures because of a larger lumen and longer stent patency. Recently, SEMS has been used for various benign biliary strictures and leaks. In this article, we briefly review the characteristics of SEMS as well as complications of stent placement. We review the current guidelines for managing malignant and benign biliary obstructions. Recent developments in biliary stenting are also discussed. PMID:26911896

  1. Recent advances of biliary stent management.

    Science.gov (United States)

    Kida, Mitsuhiro; Miyazawa, Shiro; Iwai, Tomohisa; Ikeda, Hiroko; Takezawa, Miyoko; Kikuchi, Hidehiko; Watanabe, Maya; Imaizumi, Hiroshi; Koizumi, Wasaburo

    2012-01-01

    Recent progress in chemotherapy has prolonged the survival of patients with malignant biliary strictures, leading to increased rates of stent occlusion. Even we employed metallic stents which contributed to higher rates and longer durations of patency, and occlusion of covered metallic stents now occurs in about half of all patients during their survival. We investigated the complication and patency rate for the removal of covered metallic stents, and found that the durations were similar for initial stent placement and re-intervention. In order to preserve patient quality of life, we currently recommend the use of covered metallic stents for patients with malignant biliary obstruction because of their removability and longest patency duration, even though uncovered metallic stents have similar patency durations. PMID:22563289

  2. Stenting in Malignant Biliary Obstruction.

    Science.gov (United States)

    Almadi, Majid A; Barkun, Jeffrey S; Barkun, Alan N

    2015-10-01

    Decompression of the biliary system in patients with malignant biliary obstruction has been widely accepted and implemented as part of the care. Despite a wealth of literature, there remains a significant amount of uncertainty as to which approach would be most appropriate in different clinical settings. This review covers stenting of the biliary system in cases of resectable or palliative malignant biliary obstruction, potential candidates for biliary drainage, technical aspects of the procedure, as well as management of biliary stent dysfunction. Furthermore, periprocedural considerations including proper mapping of the location of obstruction and the use of antibiotics are addressed. PMID:26431598

  3. Indications for stenting during thrombolysis

    DEFF Research Database (Denmark)

    Bækgaard, N; Broholm, R; Just, Sven Richardt Lundgren

    2013-01-01

    The most important vein segment to thrombolyse after deep venous thrombosis (DVT) is the outflow tract meaning the iliofemoral vein. Iliofemoral DVT is defined as DVT in the iliac vein and the common femoral vein. Spontaneous recanalization is less than 50%, particularly on the left side...... with catheter-directed thrombolysis of iliofemoral deep venous thrombosis....... of a stent in this position is the treatment of choice facilitating the venous flow into an unobstructed outflow tract either from the femoral vein or the deep femoral vein or both. The stent, made of stainless steel or nitinol, has to be self-expandable and flexible with radial force to overcome...

  4. Multifaceted prospects of nanocomposites for cardiovascular grafts and stents

    Directory of Open Access Journals (Sweden)

    Vellayappan MV

    2015-04-01

    promoting nanocomposites as plausible candidates in a campaign against cardiovascular disease. Keywords: nanocomposites, vascular grafts, stents, hemocompatibility, nanoparticles, cardiovascular biomaterials

  5. Quantification of local hemodynamic alterations caused by virtual implantation of three commercially available stents for the treatment of aortic coarctation.

    Science.gov (United States)

    Kwon, Sung; Feinstein, Jeffrey A; Dholakia, Ronak J; Ladisa, John F

    2014-04-01

    Patients with coarctation of the aorta (CoA) are prone to morbidity including atherosclerotic plaque that has been shown to correlate with altered wall shear stress (WSS) in the descending thoracic aorta (dAo). We created the first patient-specific computational fluid dynamics (CFD) model of a CoA patient treated by Palmaz stenting to date, and compared resulting WSS distributions to those from virtual implantation of Genesis XD and modified NuMED CP stents, also commonly used for CoA. CFD models were created from magnetic resonance imaging, fluoroscopy and blood pressure data. Simulations incorporated vessel deformation, downstream vascular resistance and compliance to match measured data and generate blood flow velocity and time-averaged WSS (TAWSS) results. TAWSS was quantified longitudinally and circumferentially in the stented region and dAo. While modest differences were seen in the distal portion of the stented region, marked differences were observed downstream along the posterior dAo and depended on stent type. The Genesis XD model had the least area of TAWSS values exceeding the threshold for platelet aggregation in vitro, followed by the Palmaz and NuMED CP stents. Alterations in local blood flow patterns and WSS imparted on the dAo appear to depend on the type of stent implanted for CoA. Following confirmation in larger studies, these findings may aid pediatric interventional cardiologists in selecting the most appropriate stent for each patient, and ultimately reduce long-term morbidity following treatment for CoA by stenting.

  6. Drug eluting biliary stents to decrease stent failure rates: Areview of the literature

    Institute of Scientific and Technical Information of China (English)

    2016-01-01

    Biliary stenting is clinically effective in relieving bothmalignant and non-malignant obstructions. However, thereare high failure rates associated with tumor ingrowth andepithelial overgrowth as well as internally from biofilmdevelopment and subsequent clogging. Within the lastdecade, the use of prophylactic drug eluting stents as ameans to reduce stent failure has been investigated. Inthis review we provide an overview of the current researchon drug eluting biliary stents. While there is limited humantrial data regarding the clinical benefit of drug elutingbiliary stents in preventing stent obstruction, recentresearch suggests promise regarding their safety andpotential efficacy.

  7. A case report of very late stent thrombosis after bare-metal stent implantation

    Directory of Open Access Journals (Sweden)

    Mustafa Adem Tatlısu

    2014-03-01

    Full Text Available Stent thrombosis is undesirable complication after percutaneous coronary interventions (PCI, despite contemporary concepts of stents and antiplatelet therapy. Stent thrombosis (ST is defined by the Academic Research Concortium as: early (1 year. Risk of very late stent thrombosis is considerably higher in patients with drug-eluting stents (DES, owing to delayed endothelialization. There are several cases very late ST after bare-metal stent (BMS implantation. Our patient presented with ST-elevation myocardial infarction on account of BMS thrombosis 14 years after the implantation.

  8. An in Vitro Twist Fatigue Test of Fabric Stent-Grafts Supported by Z-Stents vs. Ringed Stents

    Directory of Open Access Journals (Sweden)

    Jing Lin

    2016-02-01

    Full Text Available Whereas buckling can cause type III endoleaks, long-term twisting of a stent-graft was investigated here as a mechanism leading to type V endoleak or endotension. Two experimental device designs supported with Z-stents having strut angles of 35° or 45° were compared to a ringed control under accelerated twisting. Damage to each device was assessed and compared after different durations of twisting, with focus on damage that may allow leakage. Stent-grafts with 35° Z-stents had the most severe distortion and damage to the graft fabric. The 45° Z-stents caused less fabric damage. However, consistent stretching was still seen around the holes for sutures, which attach the stents to the graft fabric. Larger holes may become channels for fluid percolation through the wall. The ringed stent-graft had the least damage observed. Stent apexes with sharp angles appear to be responsible for major damage to the fabrics. Device manufacturers should consider stent apex angle when designing stent-grafts, and ensure their devices are resistant to twisting.

  9. Stent malapposition, as a potential mechanism of very late stent thrombosis after bare-metal stent implantation: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Higuma, Takumi, E-mail: higuma@cc.hirosaki-u.ac.jp; Abe, Naoki; Hanada, Kenji; Yokoyama, Hiroaki; Tomita, Hirofumi; Okumura, Ken

    2014-04-15

    A 90-year-old man was admitted to our hospital with acute ST-segment elevation myocardial infarction. He had a history of post-infarction angina pectoris 79 months ago and had a bare-metal stent (BMS) implanted in the proximal left anterior descending artery at our hospital. Emergent coronary angiography demonstrated thrombotic occlusion in the previously stented segment. After catheter thrombectomy, antegrade flow was restored, but 90% stenosis with haziness persisted in the proximal and distal portions of the previously stented segment. Intravascular ultrasound imaging showed interstrut cavities or stent malapposition at the proximal and distal sites of stented segment. In close proximity to the sites, residual thrombi were also observed. Optical coherence tomography (OCT) demonstrated neither lipid-laden neointimal tissue nor rupture but clearly demonstrated residual thrombus adjacent to the malapposed region in addition to the stent malapposition. PCI with balloon was successfully performed and stent apposition was confirmed by OCT. Stent malapposition is an unusual mechanism of very late stent thrombosis after BMS implantation. OCT can clearly reveal the etiology of stent thrombosis.

  10. Vascular Complications of Pancreatitis: Role of Interventional Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Barge, Jaideep U.; Lopera, Jorge E. [University of Texas Health Science Center, San Antonio (United States)

    2012-02-15

    Major vascular complications related to pancreatitis can cause life-threatening hemorrhage and have to be dealt with as an emergency, utilizing a multidisciplinary approach of angiography, endoscopy or surgery. These may occur secondary to direct vascular injuries, which result in the formation of splanchnic pseudoaneurysms, gastrointestinal etiologies such as peptic ulcer disease and gastroesophageal varices, and post-operative bleeding related to pancreatic surgery. In this review article, we discuss the pathophysiologic mechanisms, diagnostic modalities, and treatment of pancreatic vascular complications, with a focus on the role of minimally-invasive interventional therapies such as angioembolization, endovascular stenting, and ultrasound-guided percutaneous thrombin injection in their management.

  11. Polymeric Biodegradable Stent Insertion in the Esophagus

    Directory of Open Access Journals (Sweden)

    Kai Yang

    2016-04-01

    Full Text Available Esophageal stent insertion has been used as a well-accepted and effective alternative to manage and improve the quality of life for patients diagnosed with esophageal diseases and disorders. Current stents are either permanent or temporary and are fabricated from either metal or plastic. The partially covered self-expanding metal stent (SEMS has a firm anchoring effect and prevent stent migration, however, the hyperplastic tissue reaction cause stent restenosis and make it difficult to remove. A fully covered SEMS and self-expanding plastic stent (SEPS reduced reactive hyperplasia but has a high migration rate. The main advantage that polymeric biodegradable stents (BDSs have over metal or plastic stents is that removal is not require and reduce the need for repeated stent insertion. But the slightly lower radial force of BDS may be its main shortcoming and a post-implant problem. Thus, strengthening support of BDS is a content of the research in the future. BDSs are often temporarily effective in esophageal stricture to relieve dysphagia. In the future, it can be expect that biodegradable drug-eluting stents (DES will be available to treat benign esophageal stricture, perforations or leaks with additional use as palliative modalities for treating malignant esophageal stricture, as the bridge to surgery or to maintain luminal patency during neoadjuvant chemoradiation.

  12. Treatment of malignant and benign biliary obstructions with metal stents

    International Nuclear Information System (INIS)

    The palliative treatment of malignant bilary tract obstructions using a metal stent is now an established procedure in clinical practice. An endoscopic, transpapillary approach is the first choice for implantation of the stent. If it is not possible to insert the stent in this way, which is often the case with high obstructions, a percutaneous approach is chosen. It appears to be beneficial to use a metal stent with a finemeshed net such as, for example, the Wall stent. Metal stents have a higher patency rate than plastic stents so that the primary choice of a metal stent is justified. Coated stents have not yet shown any major advantages. In cases of stent occlusion the coaxial implantation of a plastic stent seems to be the most efficient. In cases of benign biliary tract stenoses, a metal stent should only be implanted after a careful evaluation of all possible surgical modalities and exploitation of balloon dilatation and long-term splinting methods. (orig.)

  13. Evaluation of a novel stent technology: the Genous EPC capturing stent

    NARCIS (Netherlands)

    M. Klomp

    2012-01-01

    Tegenwoordig gebruiken ziekenhuizen een nieuwe stent bij dotterbehandelingen van kransslagadervernauwingen. Deze Genous-stent heeft een laag met antistoffen waardoor het behandelde bloedvat snel bedekt raakt met lichaamseigen cellen. Zo wordt tegengegaan dat er opnieuw een vernauwing optreedt of dat

  14. Endovascular Management of Vascular Injury during Transsphenoidal Surgery.

    Science.gov (United States)

    Cinar, C; Bozkaya, H; Parildar, M; Oran, I

    2013-03-01

    Vascular injury is an unusual and serious complication of transsphenoidal surgery. We aimed to define the role of angiography and endovascular treatment in patients with vascular injuries occurring during transsphenoidal surgery. During the last ten-year period, we retrospectively evaluated nine patients with vascular injury after transsphenoidal surgery. Eight patients were symptomatic due to vascular injury, while one had only suspicion of vascular injury during surgery. Four patients presented with epistaxis, two with subarachnoid hemorrhage, one with exophthalmos, and one with hemiparesia. Emergency angiography revealed a pseudoaneurysm in four patients, contrast extravasation in two, vessel dissection in one, vessel wall irregularity in one, and arteriovenous fistula in one. All patients but one were treated successfully with parent artery occlusion, with one covered stent implantation, one stent-assisted coiling method, while one patient was managed conservatively. One patient died due to complications related to the primary insult without rebleeding. Vascular injuries suspected intra or postoperatively must be investigated rapidly after transsphenoidal surgery. Endovascular treatment with parent artery occlusion is feasible with acceptable morbidity and mortality rates in the treatment of vascular injuries occurring in transsphenoidal surgery.

  15. Rapid virtual stenting for intracranial aneurysms

    Science.gov (United States)

    Zhao, Liang; Chen, Danyang; Chen, Zihe; Wang, Xiangyu; Paliwal, Nikhil; Xiang, Jianping; Meng, Hui; Corso, Jason J.; Xu, Jinhui

    2016-03-01

    The rupture of Intracranial Aneurysms is the most severe form of stroke with high rates of mortality and disability. One of its primary treatments is to use stent or Flow Diverter to divert the blood flow away from the IA in a minimal invasive manner. To optimize such treatments, it is desirable to provide an automatic tool for virtual stenting before its actual implantation. In this paper, we propose a novel method, called ball-sweeping, for rapid virtual stenting. Our method sweeps a maximum inscribed sphere through the aneurysmal region of the vessel and directly generates a stent surface touching the vessel wall without needing to iteratively grow a deformable stent surface. Our resulting stent mesh has guaranteed smoothness and variable pore density to achieve an enhanced occlusion performance. Comparing to existing methods, our technique is computationally much more efficient.

  16. Esophageal stent migration leads to intestinal obstruction

    Directory of Open Access Journals (Sweden)

    Oguzhan Karatepe

    2009-07-01

    Full Text Available Background: Self-expanding metallic stents are the devices of choice in the treatment of malign or benign strictures of esophagus. Stent migration is a well-known complication of this procedure. Aims: We report a case of intestinal obstruction caused by esophageal stent migration, in which surgical intervention was used. Methods: A 65-year-old woman, who had a medical history of gastric cancer operation and esophageal stent application admitted to our emergeny department with a 48-hour history of abdominal pain, nausea and vomiting. An emergeny laparotomy was performed and the migrated stent leading to intestinal obstruction was removed. Results: The patient recovered without incident and was discharged on postoperative day 3. Conclusion: This case illustrates that esophageal stent migration has to be considered as a potential life-threatening complication.

  17. Successful retrieval of an unexpanded coronary stent from the left main coronary artery during primary percutaneous coronary intervention

    Directory of Open Access Journals (Sweden)

    Šalinger-Martinović Sonja

    2011-01-01

    Full Text Available Introduction. Dislodgement and embolization of the new generation of coronary stents before their deployment are rare but could constitute a very serious complication. Case Outline. We report a case of a stent dislodgement into the left main coronary artery during the primary coronary intervention of infarct related left circumflex artery in a patient with acute myocardial infarction. The dislodged and unexpanded bare-metal stent FlexMaster 3.0x19 mm (Abbot Vascular was stranded and bended in the left main coronary artery (LMCA, probably by the tip of the guiding catheter, but stayed over the guidewire. It was successfully retrieved using a low-profile Ryujin 1.25x15 balloon catheter (Terumo that was passed through the stent, inflated and then pulled back into the guiding catheter. After that, the whole system was withdrawn through the 6 F arterial sheath via the transfemoral approach. After repeated cannulation via the 6F arterial sheath, additional BMW and ATW guidewires were introduced into the posterolateral and obtuse marginal branches and a bare-metal stent Driver (Medtronic Cardiovascular Inc 3.0x18 mm was implanted in the target lesion. Conclusion. Stent dislodgement is a rare but potentially life-threatening complication of the percutaneous coronary intervention. This incident occurring in the LMCA in particular during an acute myocardial infarction requires to be urgently resolved. The avoidance of rough manipulation with the guiding catheter and delivery system may help in preventing this kind of complications.

  18. Mechanical behavior of peripheral stents and stent-vessel interaction: A computational study

    Science.gov (United States)

    Dottori, Serena; Flamini, Vittoria; Vairo, Giuseppe

    2016-05-01

    In this paper stents employed to treat peripheral artery disease are analyzed through a three-dimensional finite-element approach, based on a large-strain and large-displacement formulation. Aiming to evaluate the influence of some stent design parameters on stent mechanics and on the biomechanical interaction between stent and arterial wall, quasi-static and dynamic numerical analyses are carried out by referring to computational models of commercially and noncommercially available versions of both braided self-expandable stents and balloon-expandable stents. Addressing isolated device models, opening mechanisms and flexibility of both opened and closed stent configurations are numerically experienced. Moreover, stent deployment into a stenotic peripheral artery and possible postdilatation angioplasty (the latter for the self-expandable device only) are simulated by considering different idealized vessel geometries and accounting for the presence of a stenotic plaque. Proposed results highlight important differences in the mechanical response of the two types of stents, as well as a significant influence of the vessel shape on the stress distributions arising upon the artery-plaque system. Finally, computational results are used to assess both the stent mechanical performance and the effectiveness of the stenting treatment, allowing also to identify possible critical conditions affecting the risk of stent fracture, tissue damage, and/or pathological tissue response.

  19. Acute Duodenal Obstruction After Percutaneous Placement of Metallic Biliary Stents: Peroral Treatment with Enteral Stents

    International Nuclear Information System (INIS)

    Three patients with malignant biliary obstruction were treated with placement of metallic biliary stents. Two patients had known partial duodenal stenosis but had no symptoms of gastrointestinal obstruction. The patients developed symptomatic duodenal obstruction early after biliary metallic stent placement. The symptomatic duodenal obstructions were successfully treated with peroral placement of duodenal stents, which obviated the need for surgical intervention

  20. Hypersensitivity to drug-eluting stent and stent thrombosis: Kounis or not Kounis syndrome?

    Institute of Scientific and Technical Information of China (English)

    TAN Wei; CHENG Kang-lin; CHEN Qiu-xiong

    2009-01-01

    @@ With the utilization of coronary-stents, coronary remodeling and restenosis were reduced compared with balloon angioplasty alone.~1 However, the risk of restenosis is still in the range of 15% to 20%. Drug-eluting stents (DES), which could release antiproliferative pharmacological agents after deployment. were designed to inhibit the response to injury reaction after bare-metal stent (BMS) implantation.

  1. Angle change of the parent arteries after stent-assisted coil embolization of wide-necked intracranial bifurcation aneurysms

    International Nuclear Information System (INIS)

    Aim: To investigate the angle changes of the parent arteries after stent-assisted coil embolization of wide-necked intracranial bifurcation aneurysms. Materials and methods: The adjacent parent arterial angles before and after stent-assisted coil embolization were measured in 38 patients with aneurysms of the anterior communicating artery (ACoAA) and 41 patients with bifurcation aneurysms of the middle cerebral artery (MCABA). Variables were analysed in relation to the angle changes. Results: Vascular angles of the parent arteries significantly increased by 27.8° (±18.5°) immediately after stent-assisted coil embolization in 79 cases (p < 0.001), with 25.7° (±14.8°) in ACoAA and 29.7° (±21.4°) in MCABA, respectively. In 51 (64.6%) cases with follow-up angiography (mean interval 13.5 ± 4.1 months), vascular angles increased by 27.2° (±17.1°) immediately after treatment and further increased by 20.7° (±14.3°) at the last follow-up (all p < 0.001). More acute pre-stent angles of the parent arteries correlated with greater post-stent angle changes (p = 0.006). Younger age tended to be inversely related to post-stent angle changes (p = 0.091). Conclusion: Stent placement during coil embolization induced significant changes in the aneurysm–parent artery relationship. Further study is needed to elicit the association between angle change of the parent arteries and aneurysmal stability after coil embolization

  2. Evaluation of the combined application of ultrasound imaging techniques for middle cerebral artery stent surveillance and follow-up study.

    Directory of Open Access Journals (Sweden)

    Yu Wang

    Full Text Available OBJECTIVE: In recent years, cerebral artery stenting has become an effective method for the treatment of cerebral artery stenosis. However, methods for assessing efficacy and techniques for follow-up imaging still need to be developed. This study was designed to evaluate the application of transcranial color-coded sonography (TCCS in assessing stenting of middle cerebral artery (MCA stenosis. And, two new imaging techniques (vascular enhancement technology (VET and 3-dimensional (3D imaging were tried out and evaluated. METHOD: We enrolled 43 patients with cerebral artery stenosis for vascular stent implantation. All patients were examined by ultrasonography and confirmed through digital subtraction angiography. The stenosis was imaged and blood flow parameters were analyzed before and after the procedure using TCCS. VET and 3D imaging model were used in part of the patients. Important postoperative hemodynamic changes were noted. RESULTS: 1 Adequate stent image was present in 41 out of 43 patients as detected by postoperative 2-dimensional imaging. Images lacking clarity were obtained in 2 patients. 2 The perioperative and postoperative (one week follow-up instantaneous blood flow velocity at the site of stenosis was significantly decreased (P0.05. 3 VET imaging visualizes the MCA lumen and stent morphology clearly. 3D ultrasound can be used for imaging of the stent shape as well as its inner surface. CONCLUSION: TCCD can be considered a quick and effective clinical detection method to evaluate the intracranial arterial hemodynamics changes before and after stenting treatment for MCA stenosis. New imaging technologies 3D and VET can achieve additional image information.

  3. Endothelial responses of magnesium and other alloying elements in magnesium-based stent materials

    Science.gov (United States)

    Zhao, Nan; Zhu, Donghui

    2016-01-01

    Biodegradable tailored magnesium (Mg) alloys are some of the most promising scaffolds for cardiovascular stents. During the course of degradation after implantation, all the alloying elements in the scaffold will be released to the surrounding vascular tissues. However, fundamental questions regarding the toxicity of alloying elements towards vascular cells, the maximum amount of each element that could be used in alloy design, or how each of the alloying elements affects vascular cellular activity and gene expression, are still not fully answered. This work systematically addressed these questions by revealing how application of different alloying elements commonly used in Mg stent materials influences several indices of human endothelial cell health, i.e., viability, proliferations, cytoskeletal reorganizations, migration, and the gene expression profile. The overall cell viability and proliferation showed a decreasing trend with increasing concentrations of the ions, and the half maximal effective concentrations (EC50) for each element were determined. When applied at a low concentration of around 10 mM, Mg had no adverse effects but improved cell proliferation and migration instead. Mg ions also altered endothelial gene expression significantly in a dose dependent manner. Most of the changed genes are related to angiogenesis and the cell adhesion signaling pathways. Findings from this work provide useful information on maximum safe doses of these ions for endothelial cells, endothelial responses towards these metal ions, and some guidance for future Mg stent design. PMID:25363018

  4. Stent implantation influence wall shear stress evolution

    Science.gov (United States)

    Bernad, S. I.; Totorean, A. F.; Bosioc, A. I.; Petre, I.; Bernad, E. S.

    2016-06-01

    Local hemodynamic factors are known affect the natural history of the restenosis critically after coronary stenting of atherosclerosis. Stent-induced flows disturbance magnitude dependent directly on the strut design. The impact of flow alterations around struts vary as the strut geometrical parameters change. Our results provide data regarding the hemodynamic parameters for the blood flow in both stenosed and stented coronary artery under physiological conditions, namely wall shear stress and pressure drop.

  5. Photodynamic therapy for occluded biliary metal stents

    Science.gov (United States)

    Roche, Joseph V. E.; Krasner, Neville; Sturgess, R.

    1999-02-01

    In this abstract we describe the use of photodynamic therapy (PDT) to recanalize occluded biliary metal stents. In patients with jaundice secondary to obstructed metal stents PDT was carried out 72 hours after the administration of m THPC. Red laser light at 652 nm was delivered endoscopically at an energy intensity of 50 J/cm. A week later endoscopic retrograde cholangiogram showed complete recanalization of the metal stent.

  6. Very Late Bare Metal Stent Thrombosis

    Directory of Open Access Journals (Sweden)

    Mariana Soto Herrera

    2013-01-01

    Full Text Available Very late stent thrombosis is a rare and not-well-understood complication after bare metal stent implantation. It usually presents as an ST elevation acute coronary syndrome and it is associated with high rates of morbidity and mortality. Pathophysiologic mechanisms are not well defined; nevertheless, recent studies have proposed a neoatherosclerotic process as the triggering mechanism. We present the case of a patient with bare metal very late stent thrombosis 12 years after implantation.

  7. Very Late Bare Metal Stent Thrombosis

    Science.gov (United States)

    Soto Herrera, Mariana; Restrepo, José A.; Felipe Buitrago, Andrés; Gómez Mejía, Mabel; Díaz, Jesús H.

    2013-01-01

    Very late stent thrombosis is a rare and not-well-understood complication after bare metal stent implantation. It usually presents as an ST elevation acute coronary syndrome and it is associated with high rates of morbidity and mortality. Pathophysiologic mechanisms are not well defined; nevertheless, recent studies have proposed a neoatherosclerotic process as the triggering mechanism. We present the case of a patient with bare metal very late stent thrombosis 12 years after implantation. PMID:24829831

  8. Assessment of Coronary Stents by 64-slice Computed Tomography:In-stent Lumen Visibility and Patency

    Institute of Scientific and Technical Information of China (English)

    Ling-yan Kong; Zheng-yu Jin; Shu-yang Zhang; Zhu-hua Zhang; Yi-ning Wang; Lan Song; Xiao-na Zhang; Yun-qing Zhang

    2009-01-01

    Objective To assess lumen visibility of coronary stents by 64-slice computed tomography(CT)coronary angiography,and determine the value of 64-slice CT in non-invasive detecting of in-stent restenosis after coronary artery stent implantation.Methods Totally,60 patients(54 males,aged 57.0±12.7 years)and 105 stents were investigated by 64-slice CT at a mean interval of 20.0±16.6 months after coronary stents implantation.Axial multi-planar reconstruction images of the stents and curved-planar reconstruction images through the median of the stents were reconstructed for evaluating stent image quality on a 5-point scale(1=excellent,5=nonassessable),and stent lumen diameter was detected.Conventional coronary angiography was performed in 18 patients,and 32 stents were evaluated.Results Image quality was good to excellent on average(score 1.71±0.76).Stent image quality score was correlated to heart rate(r=0.281,P<0.01)and stent diameter(r=0.480,P<0.001).All the stents were assessable in lumen visibility with an average visible lumen diameter percentage of 60.7% ±13.6% .Visible lumen diameter percentage was correlated to heart rate(r=-0.193,P<0.05),stent diameter (r=0.403,P<0.001),and stent image quality score(r=-0.500,P<0.001).Visible lumen diameter percentage also varied depending on the stent type.In comparison with the conventional coronary angiography,4 of 6 in-stent stenoses were correctly detected.The sensitivity and specificity for the detection of in-stent stenosis were 66.7% and 84.6% ,respectively.Conclusions Using a 64-slice CT,the stent lumen is partly visible in most of the stents.And 64-slice CT may be useful in the assessment of stent patency.

  9. Update on Pancreatobiliary Stents: Stent Placement in Advanced Hilar Tumors

    OpenAIRE

    Jang, Sung Ill; Lee, Dong Ki

    2015-01-01

    Palliative drainage is the main treatment option for inoperable hilar cholangiocarcinoma to improve symptoms, which include cholangitis, pruritus, high-grade jaundice, and abdominal pain. Although there is no consensus on the optimal method for biliary drainage due to the paucity of large-scale randomized control studies, several important aspects of any optimal method have been studied. In this review article, we discuss the liver volume to be drained, stent type, techniques to insert self-e...

  10. Stenting:84 Cases of Clinical Application

    Institute of Scientific and Technical Information of China (English)

    GUANG Yongsong

    2002-01-01

    Objective To evaluate clinical application of therapeutic stenting. Methods 84 cases were managed with stents clinically, 136 procedures of intervention in all. The cases were suffering from portal hypertension of cirrhosis, stricture of inferior vana cava, superior vana cava syndrome, post- operative esophageal stricture, narrowig of femoral, common carotid, renal, superior mesentery arteries and biliary tract, etc. Results Therapeutic stenting achieves clinical effects completely different from conventional intemal medicine and surgery. Conclusion Therapeutic stenting is clinically unique, dramatically effective, with minor risks and worthy promoting.

  11. New stent delivery balloon: a technical note.

    Science.gov (United States)

    di Mario, C; Reimers, B; Reinhardt, R; Ferraro, M; Moussa, I; Colombo, A

    1997-12-01

    This study reports the first clinical application of a new noncompliant balloon composed of a middle polyurethane layer sandwiched between an inner layer of polyethylene terephtalate and an outer membrane that provides for consistent even expansion. With this balloon design, the very low compliance and high pressure resistance of polyethylene terephthalate are associated with the high elasticity of polyurethane, preventing balloon damage from stent crimping and expansion and allowing a firm embedding of the stent struts. Palmaz-Schatz stent implantation was successful in 33/35 stents (94%), and the two stents that could not be advanced up to the lesion were successfully withdrawn. High pressure expansion of the stent was obtained during deployment with no balloon ruptures at inflation pressures equal or lower than 16 atmospheres (atm). Accurate positioning of the stent was facilitated by the two markers at the balloon ends and by the optimal visualization after contrast injection, even with 6 Fr guiding catheters. This new delivery system maintains the advantages of hand-crimped stents on noncompliant balloons, reducing the risk of stent loss. PMID:9408637

  12. [Influence of curcumin--loaded poly (lactide-co-glycolide) films on the proliferation of vascular smooth muscle cells].

    Science.gov (United States)

    Ren, Ling; Wang, Jin; Tang, Jiaju; Pan, Changjiang; Huang, Nan

    2008-08-01

    In-stent restenosis is the major problem of percutaneous coronary interventions. Drug-eluting stent became a landmark in the treatment of coronary disease. Curcumin could be used for drug-eluting stent due to its antithrombogenity and antiproliferative properties. In this paper, 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays were performed to decide the optimal concentration of curcumin for inhibiting the proliferation of vascular smooth muscle cells (VSMC). The result disclosed that more than 80% of VSMC were inhibited when the concentration of curcumin ranged from 2.5 microg/ml to 10 microg/ml (P 316 stainless steel (SS). Therefore, these films may be used for stent coating to inhibit the in-stent restenosis induced by VSMC proliferation. PMID:18792454

  13. Intravascular Stenting in Microvascular Anastomoses

    DEFF Research Database (Denmark)

    Assersen, Kristine; Sørensen, Jens

    2015-01-01

    Background The effect of intravascular stenting (IVaS) on microvascular anastomoses has given adverse results. For experienced microsurgeons the benefit of IVaS is doubtful. We have investigated the potential benefit of the IVaS technique for two groups of inexperienced microsurgeons with different...... surgical levels of experience (medical students and young residents). Experienced microsurgeons acted as a control group. Materials and Methods In an experimental crossover study, 139 microsurgical anastomoses were performed on the femoral artery in 70 rats by 10 surgeons. On one side of the rat, the IVaS...... spent on the anastomosis. Results No significant difference in patency rates was seen between the stenting and conventional technique in all three groups. The experienced microsurgeons had 100% patency rate with both techniques. The medical students had 20/28 in the IVaS and 19/28 conventional group...

  14. Aorta Segmentation for Stent Simulation

    CERN Document Server

    Egger, Jan; Setser, Randolph; Renapuraar, Rahul; Biermann, Christina; O'Donnell, Thomas

    2011-01-01

    Simulation of arterial stenting procedures prior to intervention allows for appropriate device selection as well as highlights potential complications. To this end, we present a framework for facilitating virtual aortic stenting from a contrast computer tomography (CT) scan. More specifically, we present a method for both lumen and outer wall segmentation that may be employed in determining both the appropriateness of intervention as well as the selection and localization of the device. The more challenging recovery of the outer wall is based on a novel minimal closure tracking algorithm. Our aortic segmentation method has been validated on over 3000 multiplanar reformatting (MPR) planes from 50 CT angiography data sets yielding a Dice Similarity Coefficient (DSC) of 90.67%.

  15. Delayed cerebral infarction due to stent folding deformation following carotid artery stenting

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Kwon Duk; Lee, Kyung Yul; Suh, Sang Hyun [Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Kim, Byung Moon [Dept. of Radiology, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of)

    2014-12-15

    We report a case of delayed cerebral infarction due to stent longitudinal folding deformation following carotid artery stenting using a self-expandable stent with an open-cell design. The stented segment of the left common carotid artery was divided into two different lumens by this folding deformation, and the separated lumens became restricted with in-stent thrombosis. Although no established method of managing this rare complication exists, a conservative approach was taken with administration of anticoagulant and dual antiplatelet therapy. No neurological symptoms were observed during several months of clinical follow-up after discharge.

  16. Re-stenting treatment for esophagotracheal fistula caused by intrathoracic gastroesophageal anastomosis stent

    International Nuclear Information System (INIS)

    Objective: To evaluate the curative effect of stent replacement for the treatment of esophagotracheal fistula which occurred after the stent implantation for stenosis of intrathoracic gastroesophageal anastomotic stoma. Methods: Six patients with esophagotracheal fistula occurred after stent placement for stenosis of intrathoracic gastroesophageal anastomotic stoma were enrolled in this study. Under X-ray monitoring, the previous stent was taken out and a new, longer, covered stent was inserted into the esophagus in such a way that the stent would not be angled with the esophagus. Results: The previous stent was successfully taken out in all patients. No serious complications such as esophageal rupture, mediastinal abscess, hemorrhage, apnoea or dyspnea occurred. The replacement of the covered stent, which was 20-40 mm longer than the previous one, was also successfully performed. All the patients complained different degrees of, but tolerable, pharyngeal pain after the stenting procedure, however, the pain was markedly relieved after symptomatic treatment. Conclusion: Esophagotracheal fistula occurred after the stent implantation for stenosis of intrathoracic gastroesophageal anastomotic stoma can be effectively treated by replacing a longer covered stent. (authors)

  17. Iliocaval Confluence Stenting for Chronic Venous Obstructions

    Energy Technology Data Exchange (ETDEWEB)

    Graaf, Rick de, E-mail: r.de.graaf@mumc.nl [Maastricht University Medical Centre (MUMC), Department of Radiology (Netherlands); Wolf, Mark de, E-mail: markthewolf@gmail.com [Maastricht University Medical Centre (MUMC), Department of Surgery (Netherlands); Sailer, Anna M., E-mail: anni.sailer@mumc.nl [Maastricht University Medical Centre (MUMC), Department of Radiology (Netherlands); Laanen, Jorinde van, E-mail: jorinde.van.laanen@mumc.nl; Wittens, Cees, E-mail: c.wittens@me.com [Maastricht University Medical Centre (MUMC), Department of Surgery (Netherlands); Jalaie, Houman, E-mail: hjalaie@ukaachen.de [University Hospital Aachen, Department of Surgery (Germany)

    2015-10-15

    PurposeDifferent techniques have been described for stenting of venous obstructions. We report our experience with two different confluence stenting techniques to treat chronic bi-iliocaval obstructions.Materials and MethodsBetween 11/2009 and 08/2014 we treated 40 patients for chronic total bi-iliocaval obstructions. Pre-operative magnetic resonance venography showed bilateral extensive post-thrombotic scarring in common and external iliac veins as well as obstruction of the inferior vena cava (IVC). Stenting of the IVC was performed with large self-expandable stents down to the level of the iliocaval confluence. To bridge the confluence, either self-expandable stents were placed inside the IVC stent (24 patients, SECS group) or high radial force balloon-expandable stents were placed at the same level (16 patients, BECS group). In both cases, bilateral iliac extensions were performed using nitinol stents.ResultsRecanalization was achieved for all patients. In 15 (38 %) patients, a hybrid procedure with endophlebectomy and arteriovenous fistula creation needed to be performed because of significant involvement of inflow vessels below the inguinal ligament. Mean follow-up was 443 ± 438 days (range 7–1683 days). For all patients, primary, assisted-primary, and secondary patency rate at 36 months were 70, 73, and 78 %, respectively. Twelve-month patency rates in the SECS group were 85, 85, and 95 % for primary, assisted-primary, and secondary patency. In the BECS group, primary patency was 100 % during a mean follow-up period of 134 ± 118 (range 29–337) days.ConclusionStenting of chronic bi-iliocaval obstruction shows relatively high patency rates at medium follow-up. Short-term patency seems to favor confluence stenting with balloon-expandable stents.

  18. INTRAVASCULAR ULTRASOUND EVALUATING CORONARY STENTS FOR PATIENTS WITH CORONARY ARTERY DISEASE: COMPARED OLD WITH NEW MULTILINK STENTS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective.It was suggested that coronary stent design and coating may affect stent performance and hence induce varying degrees of thrombogenesis and neointimal hyperplasia.The purpose of this study is to compare the 6 month follow up results between old and new Multilink stents with the method of intravascular ultrasound (IVUS) imaging.Methods.We have performed old (n=40) and new (n=35) Multilink stent implantations on 75 patients with coronary artery disease.Coronary angiography was performed before,immediately after,and 6 months after the in stent procedure respectively.Six month follow up IVUS imaging was performed and analyzed off line.Results.Minimal lumen cross sectional area (CSA) of new Multilink stents was significantly larger than that of old Multilink stents (P=0.0053).Mean stent lumen area of new Multilink stents was significantly larger than that of old Multilink stents (P=0.040).Similarly,minimal lumen diameter (MLD) of new Multilink stents was larger than that of old Multilink stents (P= 0.011).Old Multilink stents had a higher percentage of plaque area than new Multilink stents.Conclusion.The new Multilink stent is obviously superior to old Multilink stents,in particular,in the stent MLD and lumen CSA- - major determinants of the restenosis.

  19. Risk Factors and Clinical Evaluation of Superficial Femoral Artery Stent Fracture: Prote'ge'GPS Stent

    International Nuclear Information System (INIS)

    To evaluate the occurrence of superficial femoral artery stent fractures, the risk factors of stent fracture, and the relationship between fractures and clinical findings. Of the 38 patients who underwent treatment with Prote'ge'GPS stenting due to arterial occlusions on the superficial femoral artery, 17 also underwent a clinical analysis. Forty-three stents were inserted in the 17 superficial femoral arteries, ranging between 15 and 50 cm in length, with a mean treated length of 26.4 cm (15-50 cm). A fracture was evaluated by taking a PA and lateral simple radiography, as well as a follow-up evaluation accompanied with a CT angiography, DSA, and a color Doppler sonography. The examination involved the assessment of the difference between bone fractures due to length, placement, and frequency. Fractures occurred in 13 of 43 stents (30.2%). A total of 10 (71.4%) occurred in the upper third, compared to 4 (28.6%) in the lower third of the superficial femoral artery. In addition, 10 stents (71.4%) had a single strut fracture, whereas 4 (28.6%) had multiple strut fractures. A stent fracture occurred more frequently when the stents and lesions were longer (p=0.021, 0.012) and the stents were inserted near the joint. However, there was no significant relationship between stent numbers and the fractures (p=0.126). When the stents were inserted along the popliteal artery, a stent fracture occurred more frequently in the lower third of the artery. The stent fractures did not significantly influence the patency rate of the stented artery (p=0.44) Prote'ge'GPS stents in the superficial femoral artery revealed a considerable number of fractures and the fracture frequency showed a significant relationship with the length of stents and lesions. The closer stent insertion was to the joints, the more frequently fractures occurred. There were no evident significant relationships between the presence of stent fractures and the patency of the stented arteries

  20. A computational study of the hemodynamic impact of open- versus closed-cell stent design in carotid artery stenting.

    Science.gov (United States)

    De Santis, Gianluca; Trachet, Bram; Conti, Michele; De Beule, Matthieu; Morbiducci, Umberto; Mortier, Peter; Segers, Patrick; Verdonck, Pascal; Verhegghe, Benedict

    2013-07-01

    The aim of this study is to analyze the shape and flow changes of a patient-specific carotid artery after carotid artery stenting (CAS) performed using an open-cell (stent-O) or a closed-cell (stent-C) stent design. First, a stent reconstructed from micro-computed tomography (microCT) is virtually implanted in a left carotid artery reconstructed from CT angiography. Second, an objective analysis of the stent-to-vessel apposition is used to quantify the lumen cross-sectional area and the incomplete stent apposition (ISA). Third, the carotid artery lumen is virtually perfused in order to quantify its resistance to flow and its exposure to atherogenic or thrombogenic hemodynamic conditions. After CAS, the minimum cross-sectional area of the internal carotid artery (ICA) (external carotid artery [ECA]) changes by +54% (-12%) with stent-O and +78% (-17%) with stent-C; the resistance to flow of the ICA (ECA) changes by -21% (+13%) with stent-O and -26% (+18%) with stent-C. Both stent designs suffer from ISA but the malapposed stent area is larger with stent-O than stent-C (29.5 vs. 14.8 mm(2) ). The untreated vessel is not exposed to atherogenic flow conditions whereas an area of 67.6 mm(2) (104.9) occurs with stent-O (stent-C). The area of the stent surface exposed to thrombogenic risk is 5.42 mm(2) (7.7) with stent-O (stent-C). The computer simulations of stenting in a patient's carotid artery reveal a trade-off between cross-sectional size and flow resistance of the ICA (enlarged and circularized) and the ECA (narrowed and ovalized). Such a trade-off, together with malapposition, atherogenic risk, and thrombogenic risk is stent-design dependent. PMID:23578331

  1. Vascular emergencies.

    Science.gov (United States)

    Semashko, D C

    1997-01-01

    This article reviews the initial assessment and emergent management of several common as well as uncommon vascular emergencies. Aortic dissection, aneurysms, and arterial occlusive disease are familiar but challenging clinical entities. Less frequently encountered conditions are also discussed including an aortic enteric fistula, mesenteric venous thrombosis, phlegmasia alba dolens, and subclavian vein thrombosis.

  2. Removal of an embedded "covered" biliary stent by the "stent-in-stent" technique

    OpenAIRE

    Menon, Shyam

    2013-01-01

    A 46-year-old man was admitted with obstructive jaundice and cross-sectional imaging with computed tomography suggested distal biliary obstruction. A distal common bile duct stricture was found at endoscopic retrograde cholangiopancreatography (ERCP) and cytology was benign. A 6 cm fully covered self-expanding metal stent (SEMS) was inserted across the stricture to optimize biliary drainage. However, the SEMS could not be removed at repeat ERCP a few months later. A further fully covered SEMS...

  3. Crush stenting in treating coronary bifurcate lesions: paclitaxel eluting stents versus sirolimus eluting stents

    Institute of Scientific and Technical Information of China (English)

    CHEN Shao-liang; SUN Xue-wen; HU Da-yi; Tak W. Kwan; ZHANG Jun-jie; YE Fei; CHEN Yun-dai; ZHU Zhong-sheng; LIN Song; TIAN Nai-liang; LIU Zhi-zhong; FANG Wei-yi

    2008-01-01

    Background Because no data regarding the comparison of crush stenting with pactitaxel(PES)or sirolimus eluting stents(SES)for coronary bifurcate lesions have been reported,we compared the clinical outcomes of these two types of stents.Methods Two hundred and thirty patients with 242 bifurcate lesions were enrolled in a prospective,nonrandomized trial.Primary endpoints included myocardial infarction,cardiac death and target vessel revascularization at 8 months.Results All patients were followed up clinically and 82%angiographically at 8 months.Final kissing balloon inflation was performed in 72%in the PES and 75%in the SES groups(P>0.05).Compared to the SES group,PES group had a higher late loss and incidence of restenosis(P=0.04)in the prebifurcation vessel segment.The postbifurcation vessel segment in the PES group had a greater late loss((0.7+0.6)mm vs(0.3±0.4)mm,P<0.001)and higher restenosis in the side branch(25.5%vs 15.6%,P=0.04)when compared to the SES group.There was significant difference of insegment restenosis in the entire main vessel between PES and SES groups (P=0.004).Target lesion revascularization was more frequently seen in the PES group as compared to the SES group(P=0.01).There was significant difference in the accumulative MACE between these two groups(P=0.01).The survival rate free from target lesion revascularization was significantly higher in the SES group when compared to the PES group(P<0.001).Conclusion SES is superior to PES in reducing restenosis and target lesion revascularization by 8-month follow-up after crush stenting for bifurcate lesions.

  4. Carotid angioplasty and stent placement for restenosis after endarterectomy

    Energy Technology Data Exchange (ETDEWEB)

    Kadkhodayan, Yasha [Washington University School of Medicine, Interventional Neuroradiology, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Moran, Christopher J.; Cross, DeWitte T. [Washington University School of Medicine, Interventional Neuroradiology, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Washington University School of Medicine, Department of Neurological Surgery, St. Louis, MO (United States); Derdeyn, Colin P. [Washington University School of Medicine, Interventional Neuroradiology, Mallinckrodt Institute of Radiology, St. Louis, MO (United States); Washington University School of Medicine, Department of Neurological Surgery, St. Louis, MO (United States); Washington University School of Medicine, Department of Neurology, St. Louis, MO (United States)

    2007-04-15

    Recurrent carotid stenosis following endarterectomy is a common complication, and reoperation may be associated with increased morbidity. The goal of this study was to determine the procedural safety and long-term complication rates of carotid angioplasty and stenting for recurrent stenosis. Of 248 consecutive carotid angioplasty and/or stenting procedures performed at our institution between March 1996 and November 2005, 83 procedures for recurrent stenosis following endarterectomy were performed in 75 patients (mean age 68 years; 43 men, 32 women) without cerebral protection devices. The patients' medical records were retrospectively reviewed for vascular imaging reports and available clinical follow-up. Procedural and long-term complication rates were calculated. Recurrent stenosis was reduced from a mean of 80.6% to no significant stenosis in 82 of 83 procedures. The procedural stroke rate was 3 out of 83 procedures (3.6%). The procedural transient ischemic attack (TIA) rate was 2 out of 83 procedures (2.4%). Mean follow-up was 22.4 months (range 0.1 to 86.7 months) with at least 6 months follow-up for 54 of 83 procedures (65%). There were five TIAs and no strokes on follow-up (new TIAs at 25.5 and 43.4 months; recurrent TIAs at 1, 11.1, and 12 months, all with normal angiograms). The composite 30-day stroke, myocardial infarction, or death rate was 5 of 83 procedures (6.0%). In this series, angioplasty and stenting were effective in relieving stenosis secondary to recurrent carotid disease after endarterectomy, and have low rates of ischemic complications. (orig.)

  5. 21 CFR 876.4620 - Ureteral stent.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ureteral stent. 876.4620 Section 876.4620 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES GASTROENTEROLOGY-UROLOGY DEVICES Surgical Devices § 876.4620 Ureteral stent. (a) Identification. A ureteral...

  6. Stent placement for esophageal strictures : an update

    NARCIS (Netherlands)

    Hirdes, Meike Madeleine Catharine; Vleggaar, Frank Paul; Siersema, Peter Derk

    2011-01-01

    The use of stents for esophageal strictures has evolved rapidly over the past 10 years, from rigid plastic tubes to flexible self-expanding metal (SEMS), plastic (SEPS) and biodegradable stents. For the palliative treatment of malignant dysphagia both SEMS and SEPS effectively provide a rapid relief

  7. Rescue coronary stenting in acute myocardial infarction

    Science.gov (United States)

    Barbieri, Enrico; Meneghetti, Paolo; Molinari, Gionata; Zardini, Piero

    1996-01-01

    Failed rescue coronary angioplasty is a high risk situation because of high mortality. Coronary stent has given us the chance of improving and maintaining the patency of the artery. We report our preliminary experience of rescue stenting after unsuccessful coronary angioplasty.

  8. Drug eluting stents: Current status and new developments

    NARCIS (Netherlands)

    G. Ertaş; H.M.M. van Beusekom (Heleen)

    2012-01-01

    textabstractDespite the favorable impact of drug eluting stents on stent restenosis, their long-term reliability is considered worrisome by some because of stent thrombosis. Often attributed to adverse reactions to the stent platform, both the drugs and polymer characteristics have been further adva

  9. Stent Graft in Managing Juxta-Renal Aortoiliac Occlusion

    International Nuclear Information System (INIS)

    Endovascular procedures are frequently used as an alternative to surgical bypass in aortic and iliac occlusion. Stents have revolutionized the scope of such endovascular procedures, but there are few reports of stents or stent grafts in occlusive juxta-renal aortic occlusion. We present a case where such occlusion was managed by use of a stent graft with successful outcome

  10. Accuracy and reproducibility of patient-specific hemodynamic models of stented intracranial aneurysms: report on the Virtual Intracranial Stenting Challenge 2011.

    Science.gov (United States)

    Cito, S; Geers, A J; Arroyo, M P; Palero, V R; Pallarés, J; Vernet, A; Blasco, J; San Román, L; Fu, W; Qiao, A; Janiga, G; Miura, Y; Ohta, M; Mendina, M; Usera, G; Frangi, A F

    2015-01-01

    Validation studies are prerequisites for computational fluid dynamics (CFD) simulations to be accepted as part of clinical decision-making. This paper reports on the 2011 edition of the Virtual Intracranial Stenting Challenge. The challenge aimed to assess the reproducibility with which research groups can simulate the velocity field in an intracranial aneurysm, both untreated and treated with five different configurations of high-porosity stents. Particle imaging velocimetry (PIV) measurements were obtained to validate the untreated velocity field. Six participants, totaling three CFD solvers, were provided with surface meshes of the vascular geometry and the deployed stent geometries, and flow rate boundary conditions for all inlets and outlets. As output, they were invited to submit an abstract to the 8th International Interdisciplinary Cerebrovascular Symposium 2011 (ICS'11), outlining their methods and giving their interpretation of the performance of each stent configuration. After the challenge, all CFD solutions were collected and analyzed. To quantitatively analyze the data, we calculated the root-mean-square error (RMSE) over uniformly distributed nodes on a plane slicing the main flow jet along its axis and normalized it with the maximum velocity on the slice of the untreated case (NRMSE). Good agreement was found between CFD and PIV with a NRMSE of 7.28%. Excellent agreement was found between CFD solutions, both untreated and treated. The maximum difference between any two groups (along a line perpendicular to the main flow jet) was 4.0 mm/s, i.e. 4.1% of the maximum velocity of the untreated case, and the average NRMSE was 0.47% (range 0.28-1.03%). In conclusion, given geometry and flow rates, research groups can accurately simulate the velocity field inside an intracranial aneurysm-as assessed by comparison with in vitro measurements-and find excellent agreement on the hemodynamic effect of different stent configurations.

  11. Stent graft placement for dysfunctional arteriovenous grafts

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Gyeong Sik [Dept. of Radiology, CHA Bundang Medical Center, College of Medicine, CHA University, Seongnam (Korea, Republic of); Shin, Byung Seok; Ohm, Joon Young; Ahn, Moon Sang [Chungnam National University Hospital, Daejeon (Korea, Republic of)

    2015-07-15

    This study aimed to evaluate the usefulness and outcomes of stent graft use in dysfunctional arteriovenous grafts. Eleven patients who underwent stent graft placement for a dysfunctional hemodialysis graft were included in this retrospective study. Expanded polytetrafluoroethylene covered stent grafts were placed at the venous anastomosis site in case of pseudoaneurysm, venous laceration, elastic recoil or residual restenosis despite the repeated angioplasty. The patency of the arteriovenous graft was evaluated using Kaplan-Meier analysis. Primary and secondary mean patency was 363 days and 741 days. Primary patency at 3, 6, and 12 months was 82%, 73%, and 32%, respectively. Secondary patency at the 3, 6, 12, 24, and 36 months was improved to 91%, 82%, 82%, 50%, and 25%, respectively. Fractures of the stent graft were observed in 2 patients, but had no effect on the patency. Stent graft placement in dysfunctional arteriovenous graft is useful and effective in prolonging graft patency.

  12. Foreign body contamination during stent implantation.

    Science.gov (United States)

    Whelan, D M; van Beusekom, H M; van der Giessen, W J

    1997-03-01

    The treatment of coronary artery disease using stents has become a widely accepted technique. However, the inadvertent co-implantation of contaminating factors with the stent has received little attention. We studied histological cross-sections of stented porcine coronary arteries and observed contamination of some vessels with surgical glove powder and textile fibres. The contaminating particles were associated with a foreign body reaction. Such a reaction could delay the wound-healing response of a stented vessel and thereby prolong the period in which subacute thrombosis could occur. It is also proposed that air contamination could affect the thrombogenicity of the stent. Appropriate measures should be followed to reduce the chance of contamination occurring.

  13. Call for standards in technical documentation of intracoronary stents.

    Science.gov (United States)

    Lanzer, Peter; Gijsen, Frank J H; Topoleski, L D Timmie; Holzapfel, Gerhard A

    2010-01-01

    At present, the product information of intracoronary stents provided by the industry contains only limited technical data restricting judgments on the in vivo performance of individual products. Available experimental and clinical evidence suggests that interventional target sites display highly heterogeneous biomechanical behavior needed to be matched by specific stent and stent delivery system characteristics. To allow individualized stent-lesion matching, both, understanding of biomechanical properties of the atherosclerotic coronary artery lesions and expert knowledge of the intracoronary stent systems, are required. Here, the authors review some of the initial data on mechanical properties of coronary artery lesions potentially relevant to stenting and suggest standards for technical documentation of intracoronary stents. PMID:20140786

  14. Bioresorbable vascular scaffolds—time to vanish?

    Science.gov (United States)

    Arroyo, Diego; Cook, Stéphane

    2016-01-01

    The fully bioabsorbable vascular scaffold (BVS) has been developed to reduce late adverse events after coronary stenting such as device thrombosis. The device consists of polylactic acid, which is gradually absorbed within the first few years after its implantation. The initial experience with the device in low-risk patients presenting with simple lesions was satisfying and generated optimism among interventional cardiologists by promising better patient outcomes. However, the unrestricted use of the device in patients presenting with a higher baseline risk and more complex lesions came at the cost of alarmingly high rates of early device thrombosis. The performance of the device largely depends on an optimal implantation technique, which differs from that employed with metallic drug-eluting stents due to the device’s distinct physical propensity. Mid-term outcomes in large-scale randomized clinical trial were disappointing. Although its non-inferiority compared to metallic everolimus-eluting stents was formally met, there was a clear trend towards an increased occurrence of myocardial infarction and device thrombosis during the first year after device implantation. However, the BVS’s putative advantages are expected to manifest themselves at long-term, that is 3 to 5 years after the device has been implanted. Evidence pertaining to these long-term outcomes is eagerly awaited. PMID:27293872

  15. What Is Vascular Disease?

    Science.gov (United States)

    ... our CEO Board of Directors Scientific Advisory Board History of Vascular Cures Impact Contact Us Vascular Disease What is Vascular Disease? Education and Awareness Vascular Diseases Abdominal Aortic Aneurysm Aortic ...

  16. Diabetes and Vascular Disease

    Science.gov (United States)

    ... our CEO Board of Directors Scientific Advisory Board History of Vascular Cures Impact Contact Us Vascular Disease What is Vascular Disease? Education and Awareness Vascular Diseases Abdominal Aortic Aneurysm Aortic ...

  17. Biliary stenting: indications, choice of stents and results: European Society of Gastrointestinal Endoscopy (ESGE) clinical guideline.

    Science.gov (United States)

    Dumonceau, J-M; Tringali, A; Blero, D; Devière, J; Laugiers, R; Heresbach, D; Costamagna, G

    2012-03-01

    This article is part of a combined publication that expresses the current view of the European Society of Gastrointestinal Endoscopy about endoscopic biliary stenting. The present Clinical Guideline describes short-term and long-term results of biliary stenting depending on indications and stent models; it makes recommendations on when, how, and with which stent to perform biliary drainage in most common clinical settings, including in patients with a potentially resectable malignant biliary obstruction and in those who require palliative drainage of common bile duct or hilar strictures. Treatment of benign conditions (strictures related to chronic pancreatitis, liver transplantation, or cholecystectomy, and leaks and failed biliary stone extraction) and management of complications (including stent revision) are also discussed. A two-page executive summary of evidence statements and recommendations is provided. A separate Technology Review describes the models of biliary stents available and the stenting techniques, including advanced techniques such as insertion of multiple plastic stents, drainage of hilar strictures, retrieval of migrated stents and combined stenting in malignant biliary and duodenal obstructions.The target readership for the Clinical Guideline mostly includes digestive endoscopists, gastroenterologists, oncologists, radiologists, internists, and surgeons while the Technology Review should be most useful to endoscopists who perform biliary drainage.

  18. Hybrid stent device of flow-diverting effect and stent-assisted coil embolization formed by fractal structure.

    Science.gov (United States)

    Kojima, Masahiro; Irie, Keiko; Masunaga, Kouhei; Sakai, Yasuhiko; Nakajima, Masahiro; Takeuchi, Masaru; Fukuda, Toshio; Arai, Fumihito; Negoro, Makoto

    2016-05-01

    This paper presents a novel hybrid medical stent device. This hybrid stent device formed by fractal mesh structures provides a flow-diverting effect and stent-assisted coil embolization. Flow-diverter stents decrease blood flow into an aneurysm to prevent its rupture. In general, the mesh size of a flow-diverter stent needs to be small enough to prevent blood flow into the aneurysm. Conventional flow-diverter stents are not available for stent-assisted coil embolization, which is an effective method for aneurysm occlusion, because the mesh size is too small to insert a micro-catheter for coil embolization. The proposed hybrid stent device is capable of stent-assisted coil embolization while simultaneously providing a flow-diverting effect. The fractal stent device is composed of mesh structures with fine and rough mesh areas. The rough mesh area can be used to insert a micro-catheter for stent-assisted coil embolization. Flow-diverting effects of two fractal stent designs were composed to three commercially available stent designs. Flow-diverting effects were analyzed using computational fluid dynamics (CFD) analysis and particle image velocimetry (PIV) experiment. Based on the CFD and PIV results, the fractal stent devices reduce the flow velocity inside an aneurism just as much as the commercially available flow-diverting stents while allowing stent-assisted coil embolization.

  19. Blood Flow Clustering and Applications in Virtual Stenting of Intracranial Aneurysms.

    Science.gov (United States)

    Oeltze, Steffen; Lehmann, Dirk J; Kuhn, Alexander; Janiga, Gabor; Theisel, Holger; Preim, Bernhard

    2014-05-01

    Understanding the hemodynamics of blood flow in vascular pathologies such as intracranial aneurysms is essential for both their diagnosis and treatment. Computational fluid dynamics (CFD) simulations of blood flow based on patient-individual data are performed to better understand aneurysm initiation and progression and more recently, for predicting treatment success. In virtual stenting, a flow-diverting mesh tube (stent) is modeled inside the reconstructed vasculature and integrated in the simulation. We focus on steady-state simulation and the resulting complex multiparameter data. The blood flow pattern captured therein is assumed to be related to the success of stenting. It is often visualized by a dense and cluttered set of streamlines.We present a fully automatic approach for reducing visual clutter and exposing characteristic flow structures by clustering streamlines and computing cluster representatives. While individual clustering techniques have been applied before to streamlines in 3D flow fields, we contribute a general quantitative and a domain-specific qualitative evaluation of three state-of-the-art techniques. We show that clustering based on streamline geometry as well as on domain-specific streamline attributes contributes to comparing and evaluating different virtual stenting strategies. With our work, we aim at supporting CFD engineers and interventional neuroradiologists.

  20. Indications and Problems of Intracranial Stenting: Report of Two Cases

    OpenAIRE

    Deguchi, J.; Kuroiwa, T; Nagasawa, S; Satoh, G.; T. Ohta

    2000-01-01

    There have been few reports of stenting in the intracranial arteries. We used coronary stents in the chronically occluded intracranial vertebral artery and stenosis of internal carotid artery by the external force, and good blood flow were resumed. Stenosis in the intracranial arteries is also a good indication for stent placement when it is due to chronic total occlusion or artery compression by external force. But stent placement in the intracranial arteries has some problems. Stent placeme...

  1. Functional Self-Expandable Metal Stents in Biliary Obstruction

    OpenAIRE

    Kwon, Chang-Il; Ko, Kwang Hyun; Hahm, Ki Baik; Kang, Dae Hwan

    2013-01-01

    Biliary stents are widely used not only for palliative treatment of malignant biliary obstruction but also for benign biliary diseases. Each plastic stent or self-expandable metal stent (SEMS) has its own advantages, and a proper stent should be selected carefully for individual condition. To compensate and overcome several drawbacks of SEMS, functional self-expandable metal stent (FSEMS) has been developed with much progress so far. This article looks into the outcomes and defects of each st...

  2. Transient coronary aneurysm formation after Nevo™ stent implantation versus persistent coronary aneurysm after Cypher Select™ stent implantation

    DEFF Research Database (Denmark)

    Christiansen, Evald Høj; Lassen, Jens Flensted; Jensen, Lisette Okkels

    2011-01-01

    We implanted a Cypher Select™ coronary stent and two months later a Nevo™ sirolimus-eluting coronary stent in another vessel. At a prescheduled angiographic follow-up, coronary aneurysms were seen in the two stented segments, 6 and 8 months after stent implantation, respectively. Six months later......, the aneurysm had healed in the Nevo, but was still present in the Cypher stented segment. We hypothesize that aneurysm formation was induced by sirolimus and the polymer of the implanted stents, and that subsequent healing was possible in the Nevo stent after degradation of the polymer....

  3. Forming of magnesium alloy microtubes in the fabrication of biodegradable stents

    Institute of Scientific and Technical Information of China (English)

    Lixiao Wang; Gang Fang; Lingyun Qian; Sander Leeflang; Jurek Duszczyk; Jie Zhou

    2014-01-01

    Magnesium alloys have, in recent years, been recognized as highly promising biodegradable materials, especially for vascular stent applications. Forming of magnesium alloys into high-precision thin-wall tubes has however presented a technological barrier in the fabrication of vascular stents, because of the poor workability of magnesium at room temperature. In the present study, the forming processes, i.e., hot indirect extrusion and multi-pass cold drawing were used to fabricate seamless microtubes of a magnesium alloy. The magnesium alloy ZM21 was selected as a representative biomaterial for biodegradable stent applications. Microtubes with an outside diameter of 2.9 mm and a wall thickness of 0.2 mm were successfully produced at the fourth pass of cold drawing without inter-pass annealing. Dimensional evaluation showed that multi-pass cold drawing was effective in correcting dimensional non-uniformity arising from hot indirect extrusion. Examinations of the microstructures of microtubes revealed the generation of a large number of twins as a result of accumulated work hardening at the third and fourth passes of cold drawing, corresponding to the significantly raised forming forces. The work demonstrated the viability of the forming process route selected for the fabrication of biodegradable magnesium alloy microtubes.

  4. Forming of magnesium alloy microtubes in the fabrication of biodegradable stents

    Directory of Open Access Journals (Sweden)

    Lixiao Wang

    2014-10-01

    Full Text Available Magnesium alloys have, in recent years, been recognized as highly promising biodegradable materials, especially for vascular stent applications. Forming of magnesium alloys into high-precision thin-wall tubes has however presented a technological barrier in the fabrication of vascular stents, because of the poor workability of magnesium at room temperature. In the present study, the forming processes, i.e., hot indirect extrusion and multi-pass cold drawing were used to fabricate seamless microtubes of a magnesium alloy. The magnesium alloy ZM21 was selected as a representative biomaterial for biodegradable stent applications. Microtubes with an outside diameter of 2.9 mm and a wall thickness of 0.2 mm were successfully produced at the fourth pass of cold drawing without inter-pass annealing. Dimensional evaluation showed that multi-pass cold drawing was effective in correcting dimensional non-uniformity arising from hot indirect extrusion. Examinations of the microstructures of microtubes revealed the generation of a large number of twins as a result of accumulated work hardening at the third and fourth passes of cold drawing, corresponding to the significantly raised forming forces. The work demonstrated the viability of the forming process route selected for the fabrication of biodegradable magnesium alloy microtubes.

  5. Safety and efficacy of polymer-free paclitaxel-eluting microporous stent in real-world practice: 1-year follow-up of the SERY-I registry

    Institute of Scientific and Technical Information of China (English)

    ZHANG Rui-yan; QIU Jian; WANG Wei; CHEN Xi-ming; YANG Zhi-iian; YAN Jin-chuan; CHEN Shao-liang; HOU Yu-qing; WU Yan-qing; LUO Hai-ming; QIU Jian-ping; ZHANG Oi; ZHU Li; WANG Yan; FU Guo-sheng; WANG Jian-an; MA Kang-hua; YIN Yue-hui; ZHANG Dai-fu; HU Xue-song; ZHU Guo-ying; SHEN Wei-feng; ZHU Jin-zhou; CHEN Liang-long; ZHANG Chen-yun; ZHOU Xu-chen; YUAN Yong; ZHONG Zhi-xiong; LI Lang

    2011-01-01

    BackgroundPolymer coating on coronary stents induces vascular inflammatory response,reduces re-endothelialization,and affects long-term outcome after percutaneous coronary intervention (PCI).The SERY-1 registry aimed to determine whether a novel polymer-free paclitaxel-eluting microporous Yinyi stent could improve 1-year outcome after index procedure in real-world clinical practice.Methods Clinical and angiographic data and follow-up outcome were collected in 1045 patients who underwent PCI with implantation of ≥1 Yinyi stents between June 2008 and August 2009 at 27 medical centers.The primary endpoint was the cumulative rate of composite major adverse cardiac events (MACE) and the secondary endpoint was the incidence of stent thrombosis at 1 year.Results Overall,1376 lesions were treated successfully with 1713 Yinyi stents,and 1019 (98.7%) patients received dual antiplatelet therapy for at least 12 months.During 1-year follow-up,8 patients (0.78%) had cardiac death,6 (0.58%)suffered non-fatal myocardial infarction,and 46 (4.46%) underwent repeat PCI due to recurrence of angina,resulting in 1-year MACE-free survival of 94.09%.Stent thrombosis occurred in 10 (0.97%) patients,and the rate of Academic Research Consortium (ARC) definite or probable stent thrombosis was 0.78%.Conclusions Polymer-free paclitaxel-eluting microporous Yinyi stent is effective and safe for interventional treatment of coronary artery disease in real-world clinical practice,without recourse to carrier polymer.Potential long-term clinical advantages of this stent deserve further investigation.

  6. Asymmetrical international attitudes

    NARCIS (Netherlands)

    Van Oudenhoven, JP; Askevis-Leherpeux, F; Hannover, B; Jaarsma, R; Dardenne, B

    2002-01-01

    In general, attitudes towards nations have a fair amount of reciprocity: nations either like each other are relatively indifferent to each other or dislike each other Sometimes, however international attitudes are asymmetrical. In this study, we use social identity theory in order to explain asymmet

  7. An asymmetric Kadison's inequality

    CERN Document Server

    Bourin, Jean-Christophe

    2010-01-01

    Some inequalities for positive linear maps on matrix algebras are given, especially asymmetric extensions of Kadison's inequality and several operator versions of Chebyshev's inequality. We also discuss well-known results around the matrix geometric mean and connect it with complex interpolation.

  8. Asymmetric reactions in continuous flow

    Directory of Open Access Journals (Sweden)

    Xiao Yin Mak

    2009-04-01

    Full Text Available An overview of asymmetric synthesis in continuous flow and microreactors is presented in this review. Applications of homogeneous and heterogeneous asymmetric catalysis as well as biocatalysis in flow are discussed.

  9. Asymmetric catalysis with helical polymers

    NARCIS (Netherlands)

    Megens, Rik P.; Roelfes, Gerard

    2011-01-01

    Inspired by nature, the use of helical biopolymer catalysts has emerged over the last years as a new approach to asymmetric catalysis. In this Concept article the various approaches and designs and their application in asymmetric catalysis will be discussed.

  10. EMPREGO DE STENTS CEREBRAIS NAS PATOLOGIAS CEREBROVASCULARES

    Directory of Open Access Journals (Sweden)

    Laís Rocha Lopes

    2015-06-01

    Full Text Available Objective: To understand the applicability and characteristics of the stents for the treatment of cerebrovascular pathologies in order to understand its viability for the therapy. Methods: Scientific articles were used based on electronic search as PubMed, Scientific Electronic Library Online (SciELO, Intechopen, Medscape. An international and up to date source of articles was used. Results: Cerebrovascular diseases have emerged as the second most important cause of mortality worldwide, from this principle we observe the importance of this study. Recently, as a solution form, stents have become a major treatment option for difficult and not feasible cerebral aneurysms single winding. Intracranial stents serve as a bridge to the neo-endothelialization by providing a reduction in blood flow into the aneurysm. The use of stents for treatment should be seriously analyzed according to their feasibility, the knowledge of the professional about their brands, features and deployment techniques, and theoretical part of the professional needs to have dexterity to the application of an intracranial stent. Conclusions: This review raises an awareness of this subject, starts from the concept of cerebrovascular disease and aneurysms as well as the genesis of the stents, progressing to elucidate all product brands and specific characteristics of each, ending with its applicability, as well as making clear the purpose and mechanism of stents.

  11. Targeting In-Stent-Stenosis with RGD- and CXCL1-Coated Mini-Stents in Mice

    Science.gov (United States)

    Weinandy, Stefan; Schreiber, Fabian; Megens, Remco T. A.; Theelen, Wendy; Smeets, Ralf; Jockenhövel, Stefan; Gries, Thomas; Möller, Martin; Klee, Doris; Weber, Christian; Zernecke, Alma

    2016-01-01

    Atherosclerotic lesions that critically narrow the artery can necessitate an angioplasty and stent implantation. Long-term therapeutic effects, however, are limited by excessive arterial remodeling. We here employed a miniaturized nitinol-stent coated with star-shaped polyethylenglycole (star-PEG), and evaluated its bio-functionalization with RGD and CXCL1 for improving in-stent stenosis after implantation into carotid arteries of mice. Nitinol foils or stents (bare metal) were coated with star-PEG, and bio-functionalized with RGD, or RGD/CXCL1. Cell adhesion to star-PEG-coated nitinol foils was unaltered or reduced, whereas bio-functionalization with RGD but foremost RGD/CXCL1 increased adhesion of early angiogenic outgrowth cells (EOCs) and endothelial cells but not smooth muscle cells when compared with bare metal foils. Stimulation of cells with RGD/CXCL1 furthermore increased the proliferation of EOCs. In vivo, bio-functionalization with RGD/CXCL1 significantly reduced neointima formation and thrombus formation, and increased re-endothelialization in apoE-/- carotid arteries compared with bare-metal nitinol stents, star-PEG-coated stents, and stents bio-functionalized with RGD only. Bio-functionalization of star-PEG-coated nitinol-stents with RGD/CXCL1 reduced in-stent neointima formation. By supporting the adhesion and proliferation of endothelial progenitor cells, RGD/CXCL1 coating of stents may help to accelerate endothelial repair after stent implantation, and thus may harbor the potential to limit the complication of in-stent restenosis in clinical approaches. PMID:27192172

  12. Targeting In-Stent-Stenosis with RGD- and CXCL1-Coated Mini-Stents in Mice.

    Directory of Open Access Journals (Sweden)

    Sakine Simsekyilmaz

    Full Text Available Atherosclerotic lesions that critically narrow the artery can necessitate an angioplasty and stent implantation. Long-term therapeutic effects, however, are limited by excessive arterial remodeling. We here employed a miniaturized nitinol-stent coated with star-shaped polyethylenglycole (star-PEG, and evaluated its bio-functionalization with RGD and CXCL1 for improving in-stent stenosis after implantation into carotid arteries of mice. Nitinol foils or stents (bare metal were coated with star-PEG, and bio-functionalized with RGD, or RGD/CXCL1. Cell adhesion to star-PEG-coated nitinol foils was unaltered or reduced, whereas bio-functionalization with RGD but foremost RGD/CXCL1 increased adhesion of early angiogenic outgrowth cells (EOCs and endothelial cells but not smooth muscle cells when compared with bare metal foils. Stimulation of cells with RGD/CXCL1 furthermore increased the proliferation of EOCs. In vivo, bio-functionalization with RGD/CXCL1 significantly reduced neointima formation and thrombus formation, and increased re-endothelialization in apoE-/- carotid arteries compared with bare-metal nitinol stents, star-PEG-coated stents, and stents bio-functionalized with RGD only. Bio-functionalization of star-PEG-coated nitinol-stents with RGD/CXCL1 reduced in-stent neointima formation. By supporting the adhesion and proliferation of endothelial progenitor cells, RGD/CXCL1 coating of stents may help to accelerate endothelial repair after stent implantation, and thus may harbor the potential to limit the complication of in-stent restenosis in clinical approaches.

  13. Biolimus-eluting stents with biodegradable polymer versus bare-metal stents in acute myocardial infarction

    DEFF Research Database (Denmark)

    Räber, Lorenz; Kelbæk, Henning; Taniwaki, Masanori;

    2014-01-01

    BACKGROUND: This study sought to determine whether the 1-year differences in major adverse cardiac event between a stent eluting biolimus from a biodegradable polymer and bare-metal stents (BMSs) in the COMFORTABLE trial (Comparison of Biolimus Eluted From an Erodible Stent Coating With Bare Meta......, BES continued to improve cardiovascular events compared with BMS beyond 1 year. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NTC00962416....

  14. Targeting In-Stent-Stenosis with RGD- and CXCL1-Coated Mini-Stents in Mice.

    Science.gov (United States)

    Simsekyilmaz, Sakine; Liehn, Elisa A; Weinandy, Stefan; Schreiber, Fabian; Megens, Remco T A; Theelen, Wendy; Smeets, Ralf; Jockenhövel, Stefan; Gries, Thomas; Möller, Martin; Klee, Doris; Weber, Christian; Zernecke, Alma

    2016-01-01

    Atherosclerotic lesions that critically narrow the artery can necessitate an angioplasty and stent implantation. Long-term therapeutic effects, however, are limited by excessive arterial remodeling. We here employed a miniaturized nitinol-stent coated with star-shaped polyethylenglycole (star-PEG), and evaluated its bio-functionalization with RGD and CXCL1 for improving in-stent stenosis after implantation into carotid arteries of mice. Nitinol foils or stents (bare metal) were coated with star-PEG, and bio-functionalized with RGD, or RGD/CXCL1. Cell adhesion to star-PEG-coated nitinol foils was unaltered or reduced, whereas bio-functionalization with RGD but foremost RGD/CXCL1 increased adhesion of early angiogenic outgrowth cells (EOCs) and endothelial cells but not smooth muscle cells when compared with bare metal foils. Stimulation of cells with RGD/CXCL1 furthermore increased the proliferation of EOCs. In vivo, bio-functionalization with RGD/CXCL1 significantly reduced neointima formation and thrombus formation, and increased re-endothelialization in apoE-/- carotid arteries compared with bare-metal nitinol stents, star-PEG-coated stents, and stents bio-functionalized with RGD only. Bio-functionalization of star-PEG-coated nitinol-stents with RGD/CXCL1 reduced in-stent neointima formation. By supporting the adhesion and proliferation of endothelial progenitor cells, RGD/CXCL1 coating of stents may help to accelerate endothelial repair after stent implantation, and thus may harbor the potential to limit the complication of in-stent restenosis in clinical approaches.

  15. Acute stent thrombosis after bifurcation stenting with the crush technique visualized with 64-slice computed tomography

    DEFF Research Database (Denmark)

    Kristensen, T.S.; Engstrom, T.; Kofoed, Klaus Fuglsang

    2008-01-01

    Acute stent thrombosis remains a potential complication after stent implantation. With the introduction of electrocardiographic gated multidetector row computed tomography (MDCT), a new nonnvasive imaging modality has become available that may contribute to the detection of complications after co...... complex interventional procedures. We present a case where CT angiography was performed just prior to the clinical presentation of acute stent thrombosis in a 55-year-old male who was treated with the crush technique in a bifurcation lesion Udgivelsesdato: 2008/7...

  16. Is provisional stenting the effective option? The WIDEST study (Wiktor stent in de novo stenosis)

    OpenAIRE

    Fluck, D.; Chenu, P; Mills, P; Davies, A; Street, J.; Paul, E; Balcon, R; Layton, C; Investigators', G

    2000-01-01

    AIM—To compare the immediate and late outcomes of patients treated by a policy of routine stent implantation with routine balloon angioplasty and the use of stents only when an ideal result has not been obtained.
METHODS—A nine centre, multinational, randomised study of 300 patients with coronary artery disease thought suitable for treatment of a single lesion by balloon angioplasty or stent implantation. Only new lesions in patients who had not undergone previous bypass surgery were included...

  17. Very late stent thrombosis following the placement of a crossing Y-stent with dual closed-cell stents for the coiling of a wide-necked aneurysm.

    Science.gov (United States)

    Lee, Chang-Young; Kim, Chang-Hyun

    2015-02-01

    The crossing Y-stent technique is a viable option for coiling of wide-necked bifurcation aneurysms. However, little is known about the long-term impact of this technique. Very late (>1 year) stent thrombosis following the placement of a crossing Y-stent with dual closed-cell stents for the coiling of a wide-necked basilar tip aneurysm, which has not been reported to date, is described.

  18. In vitro study on the feasibility of magnetic stent hyperthermia for the treatment of cardiovascular restenosis.

    Science.gov (United States)

    Li, Li; Wang, Rui; Shi, Huan-Huan; Xie, LE; Li, Jing-Ding-Sha; Kong, Wei-Chao; Tang, Jin-Tian; Ke, DA-Nian; Zhao, Ling-Yun

    2013-08-01

    Thermal treatment or hyperthermia has received considerable attention in recent years due to its high efficiency, safety and relatively few side-effects. In this study, we investigated whether it was possible to utilize targeted thermal or instent thermal treatments for the treatment of restenosis following percutaneous transluminal coronary angioplasty (PTCA) through magnetic stent hyperthermia (MSH). A 316L stainless steel stent and rabbit vascular smooth muscle cells (VSMCs) were used in the present study, in which the inductive heating characteristics of the stent under alternative magnetic field (AMF) exposure, as well as the effect of MSH on the proliferation, apoptosis, cell cycle and proliferating cell nuclear antigen (PCNA) expression of the rabbit VSMCs, were evaluated. The results demonstrated that 316L stainless steel coronary stents possess ideal inductive heating characteristics under 300 kHz AMF exposure. The heating properties were shown to be affected by the field intensity of the AMF, as well as the orientation the stent axis. MSH had a significant effect on the proliferation and apoptosis of VSMCs, and the effect was temperature-dependent. While a mild temperature of 43°C demonstrated negligible effects on the growth of VSMCs, MSH treatment above 47°C effectively inhibited the VSMC proliferation and induced apoptosis. Furthermore, a 47°C treatment exhibited a significant and long-term inhibitory effect on VSMC migration. The results strongly suggested that MSH may be potentially applied in the clinic as an alternative approach for the prevention and treatment of restenosis. PMID:24137187

  19. A finite element study of balloon expandable stent for plaque and arterial wall vulnerability assessment

    Science.gov (United States)

    Karimi, Alireza; Navidbakhsh, Mahdi; Razaghi, Reza

    2014-07-01

    The stresses induced within plaque tissues and arterial layers during stent expansion inside an atherosclerotic artery can be exceeded from the yield stresses of those tissues and, consequently, lead to plaque or arterial layer rupture. The distribution and magnitude of the stresses in each component involved in stenting might be clearly different for different plaque types and different arterial layers. In this study, a nonlinear finite element simulation was employed to investigate the effect of plaque composition (calcified, cellular, and hypocellular) on the stresses induced in the arterial layers (intima, media, and adventitia) during implantation of a balloon expandable coronary stent into a stenosed artery. The atherosclerotic artery was assumed to consist of a plaque and normal/healthy arterial tissues on its outer side. The results indicated a significant influence of plaque types on the maximum stresses induced within the plaque wall and arterial layers during stenting but not when computing maximum stress on the stent. The stress on the stiffest calcified plaque wall was in the fracture level (2.38 MPa), whereas cellular and hypocellular plaques remain stable owing to less stress on their walls. Regardless of plaque types, the highest von Mises stresses were observed on the stiffest intima layer, whereas the lowest stresses were seen to be located in less stiff media layer. The computed stresses on the intima layer were found to be high enough to initiate a rupture in this stiff layer. These findings suggest a higher risk of arterial vascular injury for the intima layer, while a lower risk of arterial injury for the media and adventitia layers.

  20. Percutaneous endovascular stent-graft treatment of aortic aneurysms and dissections: new techniques and initial experience

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Do Yun; Choi, Dong Hoon; Kang, Sung Gwon; Lee, Kwang Hoon; Won, Jong Yun [Yonsei University College of Medicine, Seoul (Korea, Republic of); Kang, Sung Gwon [Chosun University College of Medicine, Gwangju (Korea, Republic of); Won, Je Whan [Aju University College of Medicine, Suwon (Korea, Republic of); Song, Ho Young [Ulsan University College of Medicine, Seoul (Korea, Republic of)

    2003-01-01

    To evaluate the feasibility, safety and effectiveness of a newly designed percutaneously implanted separate stent-graft (SSG) for the treatment of aortic aneurysms and dissections. Using a percutaneous technique, SSG placement (in the descending thoracic aorta in 26 cases and infrarenal abdominal aorta in 24) was attempted in 50 patients with aortic aneurysms (n=27) or dissection (n=23). All SSGs were individually constructed using self-expandable nitinol stents and a Dacron graft, and were introduced through a 12 F sheath and expanded to a diameter of 20-34 mm. In all cases, vascular access was through the femoral artery. The clinical status of each patient was monitored, and postoperative CT was performed within one week of the procedure and at 3-6 month intervals afterwards. Endovascular stent-graft deployment was technically successful in 49 of 50 patients (98%). The one failure was due to torsion of the unsupported graft during deployment. Successful exclusion of aneurysms and the primary entry tears of dissections was achieved in all but three patients with aortic dissection. All patients in whom technical success was achieved showed complete thrombosis of the thoracic false lumen or aneurysmal sac, and the overall technique success rate was 92%. In addition, sixteen patients demonstrated complete resolution of the dissected thoracic false lumen (n=9) or aneurysmal sac (n=7). Immediate post-operative complications occurred at the femoral puncture site in one patient with an arteriovenous fistula, and in two, a new saccular aneurysm developed at the distal margin of the stent. No patients died, and there was no instance of paraplegia, stroke, side-branch occlusion or infection during the subsequent mean follow-up period of 9.4 (range, 2 to 26) months. In patients with aortic aneurysm and dissection, treatment with a separate percutaneously inserted stent-graft is technically feasible, safe, and effective.

  1. Morphological changes of ulcerative plaque in patients received carotid angioplasty and stenting (CAS)

    Energy Technology Data Exchange (ETDEWEB)

    Sadikin, Cindy [Department of Radiology, Dokter Soetomo Hospital, Surabaya (Indonesia); Department of Radiology, Taipei Veteran General Hospital, Taipei, Taiwan (China)], E-mail: cindysadikin@walla.com; Teng, Michael Mu Huo [Department of Radiology, Taipei Veteran General Hospital, Taipei, Taiwan (China); School of Medicine, National Yang Ming University, Taipei, Taiwan (China)], E-mail: mhteng@mail2000.com.tw; Yeh, C.-C. [Department of Radiology, Taipei Veteran General Hospital, Taipei, Taiwan (China)], E-mail: ccyeh@vghtpe.gov.tw; Chang, F.-C. [Department of Radiology, Taipei Veteran General Hospital, Taipei, Taiwan (China)], E-mail: fcchang@vghtpe.gov.tw; Luo, C.-B. [Department of Radiology, Taipei Veteran General Hospital, Taipei, Taiwan (China); School of Medicine, National Yang Ming University, Taipei, Taiwan (China)], E-mail: cbluo@vghtpe.gov.tw

    2008-03-15

    Background: Carotid ulceration plaque is a strong risk factor for stroke and systemic vascular events. The purpose of this study was to assess immediate and follow-up ulcer morphology after carotid angioplasty and stenting (CAS). Methods and results: A total of 124 patients were included in the study. Ulcerative plaques were identified in 92 arteries from 81 patients (21% were asymptomatic and 79% symptomatic). The ulcer disappeared immediately after stenting in 36 (39%) of 92 arteries in 50 patients. Patients with initial mild degree of stenosis (50-69% stenosis) prior to stent, Type-3 and Type-4 ulcers were more prone to have residual ulcers immediate after stenting procedure. Ulcers located distal and proximal to the site of maximal stenosis, and ulcers extending outside of the imaginary line connecting the distal and proximal normal borders of the carotid artery were also more likely to have residual ulcers (P < 0.001). Follow-up angiograms (mean time after CAS = 10.1 months, range = 3-28 months) performed in 32 arteries (29 patients) revealed that residual ulceration disappeared in 17 lesions (53%) and became smaller in 15 lesions (47%). During follow-up, ipsilateral neurological symptoms were not evident in any of the 29 patients (mean time after CAS = 20.1 months, range = 9-41 months). Conclusions: Ulceration morphology, and stenosis severity prior to stent procedure had an impact on ulcer coverage after CAS. Our findings suggest that residual ulcers disappear or improve over time and that with appropriate medication, will not lead to embolic strokes.

  2. Gravity-induced asymmetric distribution of a plant growth hormone

    Science.gov (United States)

    Bandurski, R. S.; Schulze, A.; Momonoki, Y.

    1984-01-01

    Dolk (1936) demonstrated that gravistimulation induced an asymmetric distribution of auxin in a horizontally-placed shoot. An attempt is made to determine where and how that asymmetry arises, and to demonstrate that the endogenous auxin, indole-3-acetic acid, becomes asymmetrically distributed in the cortical cells of the Zea mays mesocotyl during 3 min of geostimulation. Further, indole-3-acetic acid derived by hydrolysis of an applied transport form of the hormone, indole-3-acetyl-myo-inositol, becomes asymmetrically distributed within 15 min of geostimulus time. From these and prior data is developed a working theory that the gravitational stimulus induces a selective leakage, or secretion, of the hormone from the vascular tissue to the cortical cells of the mesocotyl.

  3. Asymmetric information and economics

    Science.gov (United States)

    Frieden, B. Roy; Hawkins, Raymond J.

    2010-01-01

    We present an expression of the economic concept of asymmetric information with which it is possible to derive the dynamical laws of an economy. To illustrate the utility of this approach we show how the assumption of optimal information flow leads to a general class of investment strategies including the well-known Q theory of Tobin. Novel consequences of this formalism include a natural definition of market efficiency and an uncertainty principle relating capital stock and investment flow.

  4. Asymmetric Organocatalytic Cycloadditions

    DEFF Research Database (Denmark)

    Mose, Rasmus

    2016-01-01

    were pioneered by Otto Paul Hermann Diels and Kurt Alder who discovered what later became known as the Diels Alder reaction. The Diels Alder reaction is a [4+2] cycloaddition in which a π4 component reacts with a π2 component via a cyclic transition state to generate a 6 membered ring. This reaction...... reactions constitute the first organocatalytic asymmetric higher order cycloadditions and a rational for the periselectivity and stereoselectivity is provided based on experimental and computational investigations....

  5. Effects of Ramiprilat-Coated Stents on Neointimal Hyperplasia, Inflammation, and Arterial Healing in a Porcine Coronary Restenosis Model

    OpenAIRE

    Hong, Young Joon; Jeong, Myung Ho; Song, Sun-Jung; Sim, Doo Sun; Kim, Jung Ha; Lim, Kyung Seob; Hachinohe, Daisuke; Ahmed, Khurshid; Hwang, Seung Hwan; Lee, Min Goo; Ko, Jum Suk; Park, Keun-Ho; Yoon, Hyun Ju; Yoon, Nam Sik; Kim, Kye Hun

    2011-01-01

    Background and Objectives The renin-angiotensin-aldosterone system has been implicated in the pathogenesis of neointimal hyperplasia, and a role for angiotensin II in the migration and proliferation of vascular smooth muscle cells in restenotic lesions has been proposed. The aim of this study was to determine the anti-proliferative and anti-inflammatory effects of ramiprilat-coated stents in a porcine coronary overstretch restenosis model. Subjects and Methods Pigs were randomized into two gr...

  6. FDA Approves First Fully Dissolvable Stent

    Science.gov (United States)

    ... newly approved stent is made from a biodegradable polymer that's commonly used in medical devices designed to ... the views of MedlinePlus, the National Library of Medicine, the National Institutes of Health, the U.S. Department ...

  7. Gene Therapy for the Prevention of in- Stent Restenosis Post Coronary Angioplasty

    Directory of Open Access Journals (Sweden)

    P Ranjzad

    2005-10-01

    Full Text Available Around the world, Coronary Artery Disease (CAD is quickly becoming the most common cause of morbidity and mortality. Percutaneous coronary interventions- angioplasty and stent insertion- have proved effective and reliable treatments for CAD but their long-term efficacy is limited by the high rate of restenosis. This occurs in 30 – 50% of patients undergoing angioplasty and results in symptoms requiring repeat intervention in up to 75% of them. Stent insertion has been shown to reduce this rate but in-stent restenosis still occurs in 20-40% of cases. The high incidence of restenosis represents a large economic burden on health resources. As a consequence of the resistance of restenosis to traditional therapeutic approaches, gene therapy has emerged an attractive potential therapy for this problem. Excessive extracellular matrix (ECM deposition in the neointima is the main mechanism leading to luminal loss after coronary stenting. Transforming growth factor-β (TGF-β is a major regulator of ECM deposition and there is substantial evidence to suggest its role in restenosis. TGF-β1 is the predominant isoform in vascular tissues and its production is observed to be upregulated in human restenotic lesions and in the intima of injured animal vessels. The aim of this study is to develop, investigate and compare the effects of two potentially therapeutic recombinant, replication-deficient adenoviruses, which will give rise to the expression of transgenic proteins which antagonise the fibrogenic effects of TGF-β1 in coronary arteries post stent insertion. The cDNA for these proteins have each been inserted into replication deficient adenovirus vectors under the control of the Major Immediate/Early Murine Cytomegalovirus (MIEmCMV promoter. Virus identity and the presence of transgenes have been confirmed by restriction analysis and Southern blotting respectively. Efficient transgene expression has been confirmed in cultured porcine coronary vascular

  8. Emerging Stent and Balloon Technologies in the Femoropopliteal Arteries

    Directory of Open Access Journals (Sweden)

    Georgios Pastromas

    2014-01-01

    Full Text Available Endovascular procedures for the management of the superficial femoral (SFA and popliteal artery disease are increasingly common. Over the past decade, several stent technologies have been established which may offer new options for improved clinical outcomes. This paper reviews the current evidence for SFA and popliteal artery angioplasty and stenting, with a focus on randomized trials and registries of nitinol self-expanding stents, drug-eluting stents, dug-coated balloons, and covered stent-grafts. We also highlight the limitations of the currently available data and the future routes in peripheral arterial disease (PAD stent and balloon technology.

  9. Focal stent collapse in a patient with systemic sclerosis.

    Science.gov (United States)

    Di Francesco, L; Finci, L; Reimers, B; Di Mario, C; Colombo, A

    1998-05-01

    We report a patient with systemic sclerosis having implantation of a 35 mm beStent with immediate success but developing angina at follow-up. A focal stent collapse with focal hyperplasia in and outside the stent was documented by ultrasound after 2 mos. A 14mm Palmaz-Schatz stent was successfully deployed into the collapsed beStent, with good 6-mo angiographic result. The stent collapse was probably due to unequal distribution of radial forces and possibly reactive hyperplasia in this unique patient with systemic sclerosis.

  10. Vessel wall reactions to endovascular stent implantation

    OpenAIRE

    van Beusekom, Heleen

    1993-01-01

    textabstractIn order to gain insight in the effects of stenting, we studied the process of wound healing and the short- and long-term effect of these permanently present foreign bodies. Both thrombogenic and less thrombogenic metals were evaluated with respect to thrombogenicity and tissue response. Synthetic polymers were evaluated with respect to improving the haemocompatibility and tissue-compatibility profile of these devices. Stenting of normal porcine arteries. In Chapter 2, a balloon-e...

  11. Nasolacrimal Polyurethane Stent: Complications with CT Correlation

    International Nuclear Information System (INIS)

    Purpose: To evaluate initial results in patients with epiphora secondary to obstruction of the nasolacrimal duct treated by placement of a polyurethane stent, and to discuss the technical problems and complications arising during the procedure, with visualization of the anatomy of the drainage apparatus using computed tomography (CT). Methods: We inserted 20 polyurethane Song stents under fluoroscopic guidance after dacryocystography in 19 patients with grade 3-4 epiphora caused by idiopathic obstruction of the nasolacrimal duct. CT scans were obtained following stent placement in all patients. Results: We focus on the technical problems and complications that arose during these procedures. During negotiation of the guidewire past the obstruction at the level of the junction of the duct with the lacrimal sac, the guidewire created a false passage in a posterior suborbital direction in two cases and towards the posterior midline in another. In all cases the guidewire was withdrawn and reinserted through the proper anatomic route without further difficulty or complications. In two cases the stent was improperly positioned wholly or partially outside the nasolacrimal system (one medially, one posteriorly). In one case the stent was removed and reinserted; in the other it remains in place and functional. CT was performed in all these cases to ensure proper anatomic alignment and determine what had gone wrong. The epiphora was completely resolved in 13 cases and partially relieved in four; there were three cases of stent obstruction. Epistaxis of short duration (1 hr) occurred in seven patients and headache in one. Conclusions: Treatment of epiphora with polyurethane stents is a technique that is well tolerated by patients and achieves a high success rate, yet problems in placement may be encountered. Though no major consequences for patients are involved, cognizance of such difficulties is important to avoid incorrect positioning of stents

  12. Bilateral Metallic Stenting in Malignant Hilar Obstruction

    OpenAIRE

    Lee, Tae Hoon; Moon, Jong Ho; Park, Sang-Heum

    2014-01-01

    Endoscopic palliative biliary drainage is considered as a gold standard treatment in advanced or inoperable hilar cholangiocarcinoma. Also, metal stents are preferred over plastic stents in patients with >3 months life expectancy. However, the endoscopic intervention of advanced hilar obstruction is often more challenging and complex than that of distal malignant biliary obstructions. In this literature review, we describe the issues commonly encountered during endoscopic unilateral (single) ...

  13. Malignant biliary obstruction treated with metallic stents

    International Nuclear Information System (INIS)

    Purpose: The outcome of 33 patients with malignant biliary obstruction treated with metallic stents is presented. Materials and methods: Thirty-eight biliary metallic stents were placed in 33 patients with malignant biliary obstruction. They were 52-71 years old (mean = 61.7); 23 were male and 10 were female. The biliary obstruction was caused by biliary carcinoma (n = 16), pancreatic carcinoma (n = 2), hepatoma (n = 2), metastasis in liver (n = 3) and lymph node metastasis (n = 10). Six types and 38 metallic stents were used. After stentering, 3 cases were treated with intrastent brachytherapy, 7 cases treated with external radiotherapy and 2 patients treated with interventional radiology. Patients were followed for 6-28 months, mean 11 months. Results: Stent placement was successful in all 33 cases. The same time, 4 patients were treated with plastic tube for external drainage only. The successful rate was 90%. Twenty-nine patients were placed in one time, 4 cases began with plastic tube which was replaced with metallic stents after 1-2 weeks. Nine had metallic stents and plastic tube, because of complicated obstruction. The external drainage catheters were removed after 15-200 days. Three patients had stents crossing the ampulla. In 28 cases (84.85%), jaundice was reduced satisfactorily while in 5 cases with complicated biliary obstruction, the result was unsatisfactory. The median survival was 7 months. After stentering, 12 cases were treated with locat chemotherapy, brachytherapy or radiotherapy. The median survival period was 10 months. Conclusion: The metallic stent provides good palliative drainage and is well tolerated by patients. It improves the survival rate when combined with radiotherapy, brachytherapy and chemotherapy in patients with malignant biliary obstruction

  14. Intracoronary stents: clinical and angiographic results.

    Science.gov (United States)

    Popma, J J; Ellis, S G

    1990-10-01

    Limitations of current forms of coronary angioplasty including abrupt vessel closure and delayed restenosis have led to the development of alternative nonsurgical methods of coronary revascularization. By scaffolding the arterial dissection and smoothing the endoluminal surface, intracoronary stenting may obviate the need for emergency coronary bypass surgery in patients who develop abrupt vessel closure following coronary angioplasty. As primary therapy, its use may prevent or delay restenosis in high-risk patients; however, due to potential patient selection bias, controlled studies are needed. Currently available intracoronary stents are limited by varying degrees of inflexibility, radiolucency, and thrombogenicity. These limitations have resulted in the development of innovative stent designs using radioopaque tantalum filaments and aggressive pharmacologic treatment with antiplatelet and anti-thrombotic therapy following stent deployment. Current experimental investigation into the feasibility of intracoronary stent coating with genetically engineered endothelial cells or slow release antiproliferative agents, such as colchicine or methotrexate, may further serve to lessen the frequency of late restenosis. The optimal patient selection criteria for the use of the intracoronary stent is currently the subject of intense clinical investigation. PMID:2227766

  15. Clinical Application of Stents in Digestive Diseases

    Institute of Scientific and Technical Information of China (English)

    GUAN Yongsong

    2002-01-01

    Objective To evaluate clinical application of therapeutic stenting of digestive diseases as a new approach from conventional management. Methods 115 cases of disorders in digestive system were managed with stents clinically, 148 procedures of intervention in all. The cases were suffering from portal hypertension of cirrhosis, post - operative esophageal stricture, Stricture resulted from esophageal carcinoma, Buddi - Chari syndrome, narrowing of superior mesentery arteries and biliary tract, etc. All had had the strictured or obliterated original natural tube lumen been dilated or recanalized under the guidance of monitoring of the fluoroscope before the stent placement except those receiving TIPS needing the creation of an artificial passage within the liver to place the stent. Results Therapeutic stenting achieves clinical effects completely different from conventional internal medicine and surgery such as portal hypertension by cirrhosis with esophageal varices, megalospleen, ascites improved; jaundis relived then resided and liver function improved and appetite better in postoperative stricture of bile duct; ascites and edema of lower limbs resided in Buddi - Chari syndrom; intestininal distention disappeared, appetite and digestive function improved in stricture in superior mesentery artery; and no dysphagia and easy food intake, appetite improved in patients of stricture of postoperative esophagus and stricture resulted from esophageal carcinoma. Conclusion Therapeutic stenting is clinically unique, dramatically effective, with minor risks and worthy promoting in the management of certain digestive disorders.

  16. SMART Control stents in femoropopliteal region

    Directory of Open Access Journals (Sweden)

    Jagić Nikola

    2008-01-01

    Full Text Available Introduction/Aim. Occlusive disease of lower limb arteries have been so far traditionally best treated with bypass surgery, but we want to find minimally invasive approach that should be at least as good as conventional surgery, and hopefully better. The aim of this study was to evaluate SMART Control stents (Cordis, J&J in Trans Atlantic Society Consensus (TASC B and C femoropopliteal lesions during one-year follow-up. Methods. Retrospective nonrandomized analysis included forty arteries in consecutive 40 patients who were stented with SMART Control stents. Primary patency at 12-month verified with Duplex Ultrasound and Acute Brachial Index (ABI as well as freedom from Target Vessel Revascularization (TVR were primary endpoints. Results. Primary technical success at stent implantation was 100%. Mean ABI values were preprocedurally 0.50, postprocedurally 0.83, at one month 0.86, at six months 0.84, at one year 0.78. After one year 39 stents were patent (97.5%. Conclusion. Excellent performance of the stent from technical point of view and a midterm results in vessel patency, as well as the absence of need for TVR were achieved. Yet, life expectancy in this cohort group of patients demands longer follow up data to draw a definite sustained positive conclusion.

  17. Healing arterial ulcers: Endothelial lining regeneration upon vascular denudation injury.

    Science.gov (United States)

    McDonald, Austin I; Iruela-Arispe, M Luisa

    2015-09-01

    Thrombosis and restenosis are the most prevalent late complications of coronary artery stenting. Current standards of clinical care focus on prevention of smooth muscle cell proliferation by the use of drug-eluting stents able to release anti-proliferative drugs. Unfortunately, these drugs also block endothelial cell proliferation and, in this manner, prevent recovery of endothelial cell coverage. Continued lack of endothelial repair leaves the root cause of thrombosis and restenosis unchanged, creating a vicious cycle where drug-mediated prevention of restenosis simultaneously implies promotion of thrombosis. In this issue of Vascular Pharmacology, Hussner and colleagues provide in vitro evidence and a mechanistic basis for the use of atorvastatin in stents as a way to bypass this roadblock. Here we review the pathological mechanisms and therapeutic approaches to restore flow in occluded arteries. We argue that rational design of drug eluting stents should focus on specific inhibition of smooth muscle cell proliferation with concurrent stimulation of endothelial regeneration. We comment on the current poor understanding of the cellular and molecular regulation of endothelial cell proliferation in the context of a functional artery, and on the pitfalls of extrapolating from the well-studied process of neovascularization by sprouting vessel formation.

  18. Does endovascular treatment of infra-inguinal arterial disease with drug-eluting stents offer better results than angioplasty with or without bare metal stents?

    Science.gov (United States)

    Antoniou, George A; Georgakarakos, Efstratios I; Antoniou, Stavros A; Georgiadis, George S

    2014-08-01

    A best evidence topic in vascular and endovascular surgery was developed according to a structured protocol. The question addressed was whether treatment of infra-inguinal arterial occlusive disease with drug-eluting stents (DESs) provides improved outcomes compared with bare metal stents (BMSs) or percutaneous balloon angioplasty (PTA) alone. Altogether, 136 papers were found using the reported searches, of which 5 provided the best evidence to answer the question. All papers represent either level 1 or 2 evidence. The authors, journal, date, country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Main outcome measures varied among the studies, and included patency, in-stent restenosis, target lesion revascularization, major adverse events, clinical improvement and limb salvage. Evidence on the comparative efficacy of DESs in femoro-popliteal arterial disease is mainly based on two randomized, controlled trials. Paclitaxel-eluting stents were evaluated in the Zilver PTX trial and demonstrated superior 2-year results to either BMSs or PTA, as indicated/shown by patency (DES vs PTA, 74.8 vs 26.5%, P < 0.01), clinical benefit (DES vs PTA, P < 0.01) and event-free survival (DES vs PTA, 86.6 vs 77.9%, P = 0.02). However, the SIROCCO trial found that the sirolimus-eluting stent did not exhibit statistically significant differences in 2-year in-stent restenosis (22.9 vs 21.1%) and target lesion revascularization (6 vs 13%) compared with the BMS. Treatment of infra-politeal arterial disease with DESs was related with superior outcomes to those of BMSs, as indicated/shown by patency, freedom from target lesion revascularization and freedom from major adverse events. Furthermore, the ACHILLES trial, the only published trial comparing the infra-popliteal DES with PTA, revealed lower angiographic restenosis (22.4 vs 41.9%, P = 0.019) and greater vessel patency (75 vs 57.1%, P = 0.025) in the DES group at 1 year

  19. Late stent thrombosis: a not negligible issue after drug-eluting stent implantation

    Institute of Scientific and Technical Information of China (English)

    GAO Run-lin

    2007-01-01

    @@ Drug-eluting stent (DES) has markedly reduced restenosis and the need for target lesion revascularization (TLR). The safety profile of DES does not seem to differ from that of bare metal stent in the acute and subacute phases following coronary intervention.

  20. Frequency and consequences of early in-stent lesions after carotid artery stent placement.

    NARCIS (Netherlands)

    Jongen, L.M.; Hendrikse, J.; Waaijer, A.; Worp, H.B. van der; Leijdekkers, V.J.; Lo, R.T.; Mali, W.P.Th.; Prokop, M.

    2009-01-01

    PURPOSE: To examine the prevalence of in-stent lesions 1 month after carotid artery stent placement with multidetector computed tomography (CT) angiography and to evaluate their possible causes and their consequences during 1-year follow-up. MATERIALS AND METHODS: Sixty-nine patients with symptomati

  1. Tratamento endovascular de dissecção crônica toracoabdominal complicada com aneurisma torácico, mediante implante de endoprótese vascular Endovascular treatment for chronic toracho-abdominal aortic dissection complicated with thoracic aneurysm, by the placement of an endovascular stent-graft

    Directory of Open Access Journals (Sweden)

    Gaudencio Espinosa

    2000-06-01

    Full Text Available Our objective is to report a case of a patient with a descending thoracic aortic aneurysm and chronic aortic dissection, who was submitted to an endovascular treatment. A 68-year-old male with coronary artery disease and hypertension, with no history of trauma, diabetes or smoking. He had myocardial infarction ten years ago. Under general anesthesia, the left femoral artery was surgically exposed and the left braquial artery was catheterized with a "pigtail" catheter, under Seldinger technique. The proximal 46mm/Æ and distal 34mm/Æ stent-graft was placed just distal to the origen of the left subclavian artery. Control arteriography showed that the lesion was completely excluded. The patient was discharged seven days after the surgery, when a computed tomographic control, was performed showing a sustained aneurysm exclusion and a satisfactory endovascular position.

  2. Society for Vascular Medicine

    Science.gov (United States)

    ... 2017 Learn more Patient Information Pages from Vascular Medicine August 2016 The Vascular Laboratory More info for ... Learn more. Trending Now: Hot Topics in Vascular Medicine Video Series Fibromuscular Dysplasia (FMD) with Drs. Jeffrey ...

  3. Interventional treatment on vascular and biliary complications after liver transplantation

    International Nuclear Information System (INIS)

    Objective: To evaluate the value of angiography and cholangiography on the diagnosis and interventional treatment on vascular and biliary complications after liver transplantation. Methods: Sixteen of 46 patients (15 males, 1 female, 17-60 years old) after orthotopic liver transplantation received angiography due to abnormal ultrasonography or edema of lower limbs, or cholangiography due to progressing jaundice. 15 cases received angiography and proved vascular complications and 4 cases received cholangiography and biliary complications were found. 3 of them appeared both vascular and biliary complications. Results: Hepatic artery complication was the most common complication (seen in 9/16 patients), including hepatic artery thrombosis or stenosis (6/9), bleeding (2/9) and hepatic artery-dissecting aneurysm (1/9). One case with hepatic artery thrombosis received transcatheter thrombolysis and two cases with bleeding received coil embolization. Stenosis of inferior vena cava and portal vein were observed in 6 and 2 patients respectively. After balloon angioplasty or stent placement, clinical symptom of all cases alleviated. Biliary complications including biliary stricture and anastomotic bile leak occurred in 4 patients. Jaundice decreased after percutaneous transhepatic cholangiography and drainage. Conclusion: Interventional methods offered both diagnosis and mini-invasive treatment for patients after liver transplantation with vascular and biliary complications. Balloon angiography and stent placement of venous stenosis is an useful procedure for the treatment of these problems

  4. Local sustained delivery of acetylsalicylic acid via hybrid stent with biodegradable nanofibers reduces adhesion of blood cells and promotes reendothelialization of the denuded artery

    Directory of Open Access Journals (Sweden)

    Lee CH

    2014-01-01

    Full Text Available Cheng-Hung Lee,1,2 Yu-Huang Lin,3 Shang-Hung Chang,1 Chun-Der Tai,3 Shih-Jung Liu,2 Yen Chu,4 Chao-Jan Wang,5 Ming-Yi Hsu,5 Hung Chang,6 Gwo-Jyh Chang,7 Kuo-Chun Hung,1 Ming-Jer Hsieh,1 Fen-Chiung Lin,1 I-Chang Hsieh,1 Ming-Shien Wen,1 Yenlin Huang81Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Linkou, 2Department of Mechanical Engineering, 3Graduate Institute of Medical Mechatronics, Chang Gung University, 4Laboratory of Cardiovascular Physiology, Division of Thoracic and Cardiovascular Surgery, 5Department of Medical Imaging and Intervention, 6Hematology-Oncology Division, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou, 7Graduate Institute of Clinical Medicinal Sciences, Chang Gung University College of Medicine, Linkou, 8Department of Anatomical Pathology, Chang Gung Memorial Hospital, Linkou, Tao-Yuan, TaiwanAbstract: Incomplete endothelialization, blood cell adhesion to vascular stents, and inflammation of arteries can result in acute stent thromboses. The systemic administration of acetylsalicylic acid decreases endothelial dysfunction, potentially reducing thrombus, enhancing vasodilatation, and inhibiting the progression of atherosclerosis; but, this is weakened by upper gastrointestinal bleeding. This study proposes a hybrid stent with biodegradable nanofibers, for the local, sustained delivery of acetylsalicylic acid to injured artery walls. Biodegradable nanofibers are prepared by first dissolving poly(D,L-lactide-co-glycolide and acetylsalicylic acid in 1,1,1,3,3,3-hexafluoro-2-propanol. The solution is then electrospun into nanofibrous tubes, which are then mounted onto commercially available bare-metal stents. In vitro release rates of pharmaceuticals from nanofibers are characterized using an elution method, and a high-performance liquid chromatography assay. The experimental results suggest that biodegradable nanofibers

  5. Secreted Matrix Metalloproteinase-9 of Proliferating Smooth Muscle Cells as a Trigger for Drug Release from Stent Surface Polymers in Coronary Arteries.

    Science.gov (United States)

    Gliesche, Daniel G; Hussner, Janine; Witzigmann, Dominik; Porta, Fabiola; Glatter, Timo; Schmidt, Alexander; Huwyler, Jörg; Meyer Zu Schwabedissen, Henriette E

    2016-07-01

    Cardiovascular diseases are the leading causes of death in industrialized countries. Atherosclerotic coronary arteries are commonly treated with percutaneous transluminal coronary intervention followed by stent deployment. This treatment has significantly improved the clinical outcome. However, triggered vascular smooth muscle cell (SMC) proliferation leads to in-stent restenosis in bare metal stents. In addition, stent thrombosis is a severe side effect of drug eluting stents due to inhibition of endothelialization. The aim of this study was to develop and test a stent surface polymer, where cytotoxic drugs are covalently conjugated to the surface and released by proteases selectively secreted by proliferating smooth muscle cells. Resting and proliferating human coronary artery smooth muscle cells (HCASMC) and endothelial cells (HCAEC) were screened to identify an enzyme exclusively released by proliferating HCASMC. Expression analyses and enzyme activity assays verified selective and exclusive activity of the matrix metalloproteinase-9 (MMP-9) in proliferating HCASMC. The principle of drug release exclusively triggered by proliferating HCASMC was tested using the biodegradable stent surface polymer poly-l-lactic acid (PLLA) and the MMP-9 cleavable peptide linkers named SRL and AVR. The specific peptide cleavage by MMP-9 was verified by attachment of the model compound fluorescein. Fluorescein release was observed in the presence of MMP-9 secreting HCASMC but not of proliferating HCAEC. Our findings suggest that cytotoxic drug conjugated polymers can be designed to selectively release the attached compound triggered by MMP-9 secreting smooth muscle cells. This novel concept may be beneficial for stent endothelialization thereby reducing the risk of restenosis and thrombosis.

  6. Stents

    Science.gov (United States)

    ... Topics Aneurysm Carotid Artery Disease Coronary Heart Disease Percutaneous Coronary Intervention Peripheral Artery Disease Send a link to NHLBI ... an artery as part of a procedure called percutaneous coronary intervention (PCI), also known as coronary angioplasty. PCI restores ...

  7. Very late bare-metal stent thrombosis, rare but stormy!

    LENUS (Irish Health Repository)

    Ali, Mohammed

    2011-08-01

    Recurrent in-stent thrombosis is rarely reported, with catastrophic clinical consequences of either acute coronary syndrome or death. We present a case of recurrent in-stent thrombosis with its outcome and a concise literature review.

  8. Innovations in Stroke Prevention: An Update on Carotid Stenting

    Medline Plus

    Full Text Available ... important thing also is that with the current role of using carotid stent angioplasty, we can get ... study results are pending, which will determine the role of carotid stenting in the healthier patients, the ...

  9. Fracture of Memotherm Metallic Stents in the Biliary Tract

    International Nuclear Information System (INIS)

    In a series of 66 patients who had palliation of malignant obstructive jaundice by percutaneous placement of Memotherm expanding metal stents, we report four cases of stent fracture. This has not been reported previously

  10. Trimming a Metallic Biliary Stent Using an Argon Plasma Coagulator

    International Nuclear Information System (INIS)

    Background. Distal migration is one of the common complications after insertion of a covered metallic stent. Stent repositioning or removal is not always possible in every patient. Therefore, trimming using an argon plasma coagulator (APC) may be a good alternative method to solve this problem. Methods. Metallic stent trimming by APC was performed in 2 patients with biliary Wallstent migration and in another patient with esophageal Ultraflex stent migration. The power setting was 60-100 watts with an argon flow of 0.8 l/min. Observations. The procedure was successfully performed and all distal parts of the stents were removed. No significant collateral damage to the nearby mucosa was observed. Conclusions. In a patient with a distally migrated metallic stent, trimming of the stent is possible by means of an APC. This new method may be applicable to other sites of metallic stent migration

  11. Innovations in Stroke Prevention: An Update on Carotid Stenting

    Medline Plus

    Full Text Available INNOVATIONS IN STROKE PREVENTION: AN UPDATE ON CAROTID STENTING NEW YORK-PRESBYTERIAN HOSPITAL NEW YORK, NY July ... MD: Good evening. Welcome to our webcast on innovations in stroke prevention: an update on carotid stenting. ...

  12. Asymmetric synthesis v.4

    CERN Document Server

    Morrison, James

    1984-01-01

    Asymmetric Synthesis, Volume 4: The Chiral Carbon Pool and Chiral Sulfur, Nitrogen, Phosphorus, and Silicon Centers describes the practical methods of obtaining chiral fragments. Divided into five chapters, this book specifically examines initial chiral transmission and extension. The opening chapter describes the so-called chiral carbon pool, the readily available chiral carbon fragments used as building blocks in synthesis. This chapter also provides a list of 375 chiral building blocks, along with their commercial sources, approximate prices, and methods of synthesis. Schemes involving

  13. A Migrated Aortic Stent Graft Causing Erosive Spondylopathy

    Energy Technology Data Exchange (ETDEWEB)

    Gestrich, Christopher, E-mail: christopher.gestrich@ukb.uni-bonn.de; Probst, Chris, E-mail: chris.probst@ukb.uni-bonn.de [Universitaetsklinikum Bonn, Department of Cardiac Surgery (Germany); Wilhelm, Kai, E-mail: kai.wilhelm@ek-bonn.de [Johanniterkrankenhaus Bonn, Department of Radiology (Germany); Schiller, Wolfgang, E-mail: wolfgang.schiller@ukb.uni-bonn.de [Universitaetsklinikum Bonn, Department of Cardiac Surgery (Germany)

    2013-12-15

    We report about a patient presenting with back pain 4 months after an uneventful endovascular implantation of an aortic stent graft. Computed tomography scan revealed a migration of the stent with consecutive endoleakage, kink formation, and movement of the stent toward the spine, which caused destruction of the aortic wall as well as vertebral necrosis. Explantation of the stent and replacement of the native aorta relieved the patient of his symptoms.

  14. Radiotherapy Prolongs Biliary Metal Stent Patency in Malignant Pancreatobiliary Obstructions

    OpenAIRE

    Park, Semi; Park, Jeong Youp; Bang, Seungmin; Park, Seung Woo; Chung, Jae Bock; Song, Si Young

    2013-01-01

    Background/Aims Biliary stenting is the most effective decompressive method for treating malignant biliary obstructive jaundice. Although the main cause of stent occlusion is tumor growth, few studies have investigated whether stent patency is affected by the combination of cancer-treatment modalities. The aim of this study was to evaluate the effects of local radiotherapy on metal-stent patency in patients with malignant biliary obstruction. Methods Patients who underwent self-expandable bil...

  15. Evaluation of different percutaneous modalities for managing malfunctioning biliary stents

    OpenAIRE

    M. Alwarraky; A. Aljaky; E. Tharwa; Aziz, A.

    2015-01-01

    Background: There is no consensus regarding optimal management of biliary metal stent occlusion. Aim: To evaluate the efficacy of different percutaneous methods for managing biliary metal stent occlusion. Patients and methods: Thirty-eight patients were included in the study. Metal biliary stent occlusions were managed by insertion of another metal stent in 18 patients (group 1), insertion of an internal–external catheter in 15 patients (group 2), and mechanical cleaning in 5 patients (...

  16. Metal stents: a bridge to surgery in hilar cholangiocarcinoma

    OpenAIRE

    Grünhagen, Dirk J.; Dunne, Declan FJ; Sturgess, Richard P; Stern, Nick; Hood, Stephen; Fenwick, Stephen W; Poston, Graeme J; Malik, Hassan Z

    2012-01-01

    Background Obstructive jaundice in patients with hilar cholangiocarcinoma is a known risk factor for hepatic failure after liver resection. Plastic stents are most widely used for preoperative drainage. However, plastic stents are known to have limited patency time and therefore, in palliative settings, the self-expanding metal stent (SEMS) is used. This type of stent has been shown to be superior because it allows for rapid biliary decompression and a reduced complication rate after insertio...

  17. Early double stent thrombosis associated with clopidogrel hyporesponsivenesss

    OpenAIRE

    Rademakers, L. M.; Dewilde, W.; van de Kerkhof, D

    2011-01-01

    A 57-year-old male patient without cardiovascular history suffered an acute myocardial infarction and underwent drug-eluting stent implantation in the left anterior descending artery. A few days later, the right coronary artery was also stented (drug-eluting stent). Three days later, he was re-admitted to our hospital in cardiogenic shock. Emergent coronary angiography showed total occlusion of both stents. Platelet function analysis (PFA) showed attenuated platelet inhibition in response to ...

  18. Metallic Stents for Tracheobronchial Pathology Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, Carolina, E-mail: carolina.serrano@unizar.es [University of Zaragoza, Surgical Pathology Unit, Animal Pathology Department (Spain); Laborda, Alicia, E-mail: alaborda@unizar.es [University of Zaragoza, Minimally Invasive Techniques Research Group (GITMI) (Spain); Lozano, Juan M., E-mail: juamauloz@gmail.com [Marly Clinic, Radiology Department (Colombia); Caballero, Hugo, E-mail: hugocaballero2007@gmail.com [Marly Clinic, Pulmonology Department (Colombia); Sebastian, Antonio, E-mail: antonio.sebastian@ono.es [Lozano Blesa Clinical University Hospital, Pulmonology Department (Spain); Lopera, Jorge, E-mail: lopera@uthscsa.edu [Health Science Center, Interventional Radiology Deparment (United States); Gregorio, Miguel Angel de, E-mail: mgregori@unizar.es [University of Zaragoza, Minimally Invasive Techniques Research Group (GITMI) (Spain)

    2013-12-15

    Purpose: To present the 7-year experience of the treatment of benign and malignant tracheobronchial stenoses using metallic stents. Patients and Methods: One hundred twenty-three stents were inserted in 86 patients (74 benign and 12 malignant stenoses). Ninety-seven stents were placed in the trachea and 26 in the bronchi. The procedures were performed under fluoroscopic and flexible bronchoscopic guidance with the patient under light sedation. In cases of severe stenotic lesions or obstructions, laser resection was performed before stent placement. Clinical and functional pulmonary data were recorded before and 3 months after the procedure. Follow-up involved clinical data and radiographic techniques at 48 h and at 1-, 3-, 6-, and 12-month intervals. Results: The technical success was 100 %. Dyspnea disappearance, forced expiratory volume in the first second, and pulmonary functional data improvement was observed in all patients (p < 0.001). Complications were detected in 23 patients (26.7 %). Mean follow-up time was 6.3 {+-} 1.2 months in patients with malignant lesions and 76.2 {+-} 2.3 months patients with in benign lesions. By the end of the study, 100 % of patients with malignant pathology and 6.7 % of patients with benign lesions had died. Conclusion: Endoluminal treatment of tracheobronchial stenosis with metallic stents is a therapeutic alternative in patients who are poor candidates for surgery. In unresectable malignant lesions, the benefit of metallic stenting is unquestionable. In benign lesions, the results are satisfactory, but sometimes other interventions are required to treat complications. New stent technology may improve these results.

  19. Effects of cobalt-chromium everolimus eluting stents or bare metal stent on fatal and non-fatal cardiovascular events

    DEFF Research Database (Denmark)

    Valgimigli, Marco; Sabaté, Manel; Kaiser, Christoph;

    2014-01-01

    eluting stents with bare metal stents were selected. The principal investigators whose trials met the inclusion criteria provided data for individual patients. PRIMARY OUTCOMES: The primary outcome was cardiac mortality. Secondary endpoints were myocardial infarction, definite stent thrombosis, definite......OBJECTIVES: To examine the safety and effectiveness of cobalt-chromium everolimus eluting stents compared with bare metal stents. DESIGN: Individual patient data meta-analysis of randomised controlled trials. Cox proportional regression models stratified by trial, containing random effects, were...... or probable stent thrombosis, target vessel revascularisation, and all cause death. RESULTS: The search yielded five randomised controlled trials, comprising 4896 participants. Compared with patients receiving bare metal stents, participants receiving cobalt-chromium everolimus eluting stents had...

  20. Modelling and simulating in-stent restenosis with complex automata

    NARCIS (Netherlands)

    A.G. Hoekstra; P. Lawford; R. Hose

    2010-01-01

    In-stent restenosis, the maladaptive response of a blood vessel to injury caused by the deployment of a stent, is a multiscale system involving a large number of biological and physical processes. We describe a Complex Automata Model for in-stent restenosis, coupling bulk flow, drug diffusion, and s

  1. 2-year patient-related versus stent-related outcomes

    DEFF Research Database (Denmark)

    Jensen, Lisette Okkels; Thayssen, Per; Christiansen, Evald Høj;

    2012-01-01

    OBJECTIVES: There are limited head-to-head randomized data on patient-related versus stent-related outcomes for everolimus-eluting stents (EES) and sirolimus-eluting stents (SES). BACKGROUND: In the SORT OUT IV (Scandinavian Organization for Randomized Trials With Clinical Outcome IV) trial, comp...

  2. Biocompatibility of phosphorylcholine coated stents in normal porcine coronary arteries

    NARCIS (Netherlands)

    D.M. Whelan (Deirdre); S.C. Krabbendam; P.D. Verdouw (Pieter); P.W.J.C. Serruys (Patrick); E.A. van Vliet (Erwin); W.J. van der Giessen (Wim); H.M.M. van Beusekom (Heleen)

    2000-01-01

    textabstractOBJECTIVE: To improve the biocompatibility of stents using a phosphorylcholine coated stent as a form of biomimicry. INTERVENTIONS: Implantation of phosphorylcholine coated (n = 20) and non-coated (n = 21) stents was performed in the coronary arteries of 25 pigs. The an

  3. Asymmetric quantum cloning machines

    International Nuclear Information System (INIS)

    A family of asymmetric cloning machines for quantum bits and N-dimensional quantum states is introduced. These machines produce two approximate copies of a single quantum state that emerge from two distinct channels. In particular, an asymmetric Pauli cloning machine is defined that makes two imperfect copies of a quantum bit, while the overall input-to-output operation for each copy is a Pauli channel. A no-cloning inequality is derived, characterizing the impossibility of copying imposed by quantum mechanics. If p and p' are the probabilities of the depolarizing channels associated with the two outputs, the domain in (√p,√p')-space located inside a particular ellipse representing close-to-perfect cloning is forbidden. This ellipse tends to a circle when copying an N-dimensional state with N→∞, which has a simple semi-classical interpretation. The symmetric Pauli cloning machines are then used to provide an upper bound on the quantum capacity of the Pauli channel of probabilities px, py and pz. The capacity is proven to be vanishing if (√px, √py, √pz) lies outside an ellipsoid whose pole coincides with the depolarizing channel that underlies the universal cloning machine. Finally, the tradeoff between the quality of the two copies is shown to result from a complementarity akin to Heisenberg uncertainty principle. (author)

  4. Asymmetric inclusion process

    Science.gov (United States)

    Reuveni, Shlomi; Eliazar, Iddo; Yechiali, Uri

    2011-10-01

    We introduce and explore the asymmetric inclusion process (ASIP), an exactly solvable bosonic counterpart of the fermionic asymmetric exclusion process (ASEP). In both processes, random events cause particles to propagate unidirectionally along a one-dimensional lattice of n sites. In the ASEP, particles are subject to exclusion interactions, whereas in the ASIP, particles are subject to inclusion interactions that coalesce them into inseparable clusters. We study the dynamics of the ASIP, derive evolution equations for the mean and probability generating function (PGF) of the sites’ occupancy vector, obtain explicit results for the above mean at steady state, and describe an iterative scheme for the computation of the PGF at steady state. We further obtain explicit results for the load distribution in steady state, with the load being the total number of particles present in all lattice sites. Finally, we address the problem of load optimization, and solve it under various criteria. The ASIP model establishes bridges between statistical physics and queueing theory as it represents a tandem array of queueing systems with (unlimited) batch service, and a tandem array of growth-collapse processes.

  5. A new experimental model of intracranial internal carotid artery and its application in testing the navigability of the covered stents

    International Nuclear Information System (INIS)

    Objective: By using rapid prototyping technique to establish a vascular model in dogs with its twisting shape simulated to the human intracranial carotid artery (ICA) and by using this vascular model to test the navigability of the Willis covered stents. Methods: A cultivated digital tube was made based on the raw MR images of human ICA. Then the digital tube was transferred into a real physical model in a 3D rapid prototyping machine. Silicon was coated. The carotid arteries of canine were exposed and cut, and then the tube was put through and anatomized to get the vascular model. Eight e-PTFE covered stents (two each at size of 3.5 mm x 16 mm, 3.5 mm x 13 mm, 3.5 mm x 10 mm and 3.5 mm x 7 mm, Shanghai Microport Co. Ltd.) were implanted one week later. Two dogs were taken as control group. Device performance was evaluated by angiography and histopathological examination. Results: Ten animal models were successfully established. Neither vascular spasm nor thrombosis was seen on angiography. Destruction of tunica media was found in the group of 3.5 mm x 16 mm and destruction of endothelium in the group of 3.5 mm x 13 mm, while only flattening of the endothelium was noted in both groups of 3.5 mm x 10 mm and 3.5 mm x 7 mm. Conclusion: Simulating the three-dimensional anatomy of human ICA and providing an effective tool for the research and for the testing of neurovascular devices, this experimental vascular model can be easily established and the procedure is of high controllability, repeatability and factuality. It is also a useful devise in training the neuroradiologists and interventional physicians. The navigability of the tested covered stents becomes decreased with the increasing of its length. (authors)

  6. Stenting and interventional radiology for obstructive jaundice in patients with unresectable biliary tract carcinomas

    OpenAIRE

    Tsuyuguchi, Toshio; Takada, Tadahiro; Miyazaki, Masaru; Miyakawa, Shuichi; Tsukada, Kazuhiro; Nagino, Masato; Kondo, Satoshi; Furuse, Junji; Saito, Hiroya; Suyama, Masafumi; Kimura, Fumio; Yoshitomi, Hideyuki; Nozawa, Satoshi; Yoshida, Masahiro; Wada, Keita

    2008-01-01

    Together with biliary drainage, which is an appropriate procedure for unresectable biliary cancer, biliary stent placement is used to improve symptoms associated with jaundice. Owing to investigations comparing percutaneous transhepatic biliary drainage (PTBD), surgical drainage, and endoscopic drainage, many types of stents are now available that can be placed endoscopically. The stents used are classified roughly as plastic stents and metal stents. Compared with plastic stents, metal stents...

  7. Local drug-delivery balloon for proliferative occlusive in-stent restenosis after drug-eluting stent

    Institute of Scientific and Technical Information of China (English)

    Gianluca Rigatelli; Paolo Cardaioli; Fabio Dell'Avvocata; Massimo Giordan

    2011-01-01

    Drug-coated balloon has been developed as an alternative to drug-eluting stents for in-stent restenosis but the performance of drug infusion balloon in such setting has not been previously described. We present a case of particularly aggressive in-stent restenosis after drug eluting stent implantation treated with a new kind of drug infusion balloon developed in order to overcome the impossibility to inflate regular drug-coated balloon for several dilatation.

  8. Sirolimus-eluting stent fractures associated with aneurysm and very late stent thrombosis in the right coronary artery

    Institute of Scientific and Technical Information of China (English)

    LIU Xuebo; Gary S.Mintz; Stéphane G.Carlier; Martin B.Leon

    2007-01-01

      Although the occurrence of coronary stent fracture is rare,recent reports showed that stent fracture after sirolimus-eluting stent(SES)implantation may be associated with neointimal hyperplasia and restenosis.We report two cases of stent fracture that occurred late after elective SES implantation into the right coronary artery(RCA)that were related to the aneurysm,restenosis,thrombosis,and vessel occlusion.……

  9. Shortening of Wallstent RP during carotid artery stenting requires appropriate stent placement.

    Science.gov (United States)

    Aikawa, Hiroshi; Nagata, Shun-ichi; Onizuka, Masanari; Tsutsumi, Masanori; Iko, Minoru; Kodama, Tomonobu; Nii, Kouhei; Matsubara, Shuko; Etou, Hosei; Go, Yoshinori; Kazekawa, Kiyoshi

    2008-06-01

    Changes in the location and length of the Wallstent RP during carotid artery stenting (CAS) were evaluated using intraoperative videos of 28 patients with carotid artery stenosis who underwent CAS with a 10/20 mm Wallstent RP to determine the appropriate stent placement. The stent was deployed after its midpoint was positioned over a virtual center line, the perpendicular line which crossed the most stenotic point of the lesion on the road mapping image. The length of the stenotic lesion, the changes in the locations of the distal and proximal ends of the stent, and the changes in stent length were examined. The distal end of the stent moved a maximum of 6.1 mm toward the proximal side to a point 19.9 mm from the virtual center line. The proximal end moved a maximum of 11.3 mm toward the distal side to a point 14.7 mm from the virtual center line. The stent length ranged from 37.7 to 44.5 mm (mean 41.2 mm). The 10/20 mm Wallstent RP placed by our technique covers the entire lesion with no less than 5.7 mm of margin over the segment distal to the lesion in patients with stenotic segments shorter than 29.4 mm.

  10. Partial stent-in-stent placement of biliary metallic stents using a short double-balloon enteroscopy

    Institute of Scientific and Technical Information of China (English)

    Koichiro Tsutsumi; Hironari Kato; Takeshi Tomoda; Kazuyuki Matsumoto; Ichiro Sakakihara; Naoki Yamamoto; Yasuhiro Noma

    2012-01-01

    Endoscopic intervention is less invasive than percutaneous or surgical approaches and should be considered the primary drainage procedure in most cases with obstructive jaundice.Recently,therapeutic endoscopic retrograde cholangiopancreatography (ERCP) using double-balloon enteroscopy (DBE) has been shown to be feasible and effective,even in patients with surgically altered anatomies.On the other hand,endoscopic partial stent-in-stent (PSIS) placement of selfexpandable metallic stents (SEMSs) for malignant hilar biliary obstruction in conventional ERCP has also been shown to be feasible,safe and effective.We performed PSIS placement of SEMSs for malignant hilar biliary obstruction due to liver metastasis using a short DBE in a patient with Roux-en-Y anastomosis and achieved technical and clinical success.This procedure can result in quick relief from obstructive jaundice in a single session and with short-term hospitalization,even in patients with surgically altered anatomies.

  11. Safety and efficacy of using the Viabahn endoprosthesis for percutaneous treatment of vascular access complications after transfemoral aortic valve implantation.

    Science.gov (United States)

    De Backer, Ole; Arnous, Samer; Sandholt, Benjamin; Brooks, Matthew; Biasco, Luigi; Franzen, Olaf; Lönn, Lars; Bech, Bo; Søndergaard, Lars

    2015-04-15

    Vascular access complications (VACs) remain one of the biggest challenges when performing transcatheter aortic valve implantation (TAVI). This study aimed to investigate the short- and medium-term safety and efficacy of the Viabahn endoprosthesis (Gore, Flagstaff, AZ) when used to treat TAVI-induced vascular injury. Over a 40-month period, 354 patients underwent true percutaneous transfemoral (TF)-TAVI using a CoreValve and Prostar-XL closure system; this was our study population. A VAC leading to acute intervention occurred in 72 patients (20.3%) - of these, 18 were managed by balloon angioplasty, 48 were treated by Viabahn stenting (technical success rate 98%), and 6 needed surgical intervention. Overall, this approach resulted in a major VAC rate of 3.1% (n = 11) in our study cohort. Length of hospitalization and 30-day mortality rates were comparable in patients with a VAC treated by Viabahn stenting versus patients without vascular complications. Two patients (4.5%) presented with new-onset claudication; one of them had the stent implanted covering the deep femoral artery (DFA). At medium-term follow-up (median 372 days; range 55 to 978 days) duplex ultrasound showed 100% patency of the Viabahn endoprostheses with no signs of stent fracture or in-stent stenosis/occlusion. In conclusion, the use of self-expanding covered stents is safe and effective in case of TF-TAVI-induced vascular injury, with good short- and medium-term outcomes. Importantly, coverage of the DFA should be avoided. If confirmed by long-term (>5 years) follow-up studies, this strategy for treating TAVI-induced VAC may be used routinely in high-risk patients. PMID:25728645

  12. Metallic stents in malignant biliary obstruction

    International Nuclear Information System (INIS)

    Purpose. Retrospective analysis of our results with metallic stent placement for malignant biliary strictures. We sought to determine parameters that influence stent patency. Methods. A total of 95 Wallstents were implanted in 65 patients (38 men, 27 women; mean age, 65.1 years) with malignant biliary obstruction. Serum bilirubin levels were assessed in 48 patients; the mean value prior to intervention was 15.0 mg/dl. Results. In 12 patients (21%) complications occurred as a result of percutaneous transhepatic drainage. Stent implantation was complicated in 13 patients, but was possible in all patients. A significant decrease in bilirubin level was seen in 83.3% of patients following stent implantation. Approximately 30% of patients developed recurrent jaundice after a mean 97.1 days. In 9 patients (15%) the recurrent jaundice was caused by stent occlusion due to tumor growth. The mean follow-up was 141.8 days, the mean survival 118.7 days. Patients with cholangiocarcinomas and gallbladder carcinomas had the best results. Worse results were seen in patients with pancreatic tumors and with lymph node metastases of colon and gastric cancers. Conclusions. The main predictive factors for occlusion rate and survival are the type of primary tumor, tumor stage, the decrease in bilirubin level, and the general condition of the patient

  13. Stent treatment of symptomatic intracranial arterial stenosis

    Directory of Open Access Journals (Sweden)

    DONG Feng-ju

    2012-08-01

    Full Text Available Objective To investigate the safety, feasibility and efficacy of the Wingspan stent in treatment of symptomatic intracranial arterial stenosis. Methods Wingspan stenting was applied in 90 cases with symptomatic intracranial arterial stenosis. The surgical success rate and periprocedural neurological complications were observed. Digital subtraction angiography was performed at 6 months after stenting to detect the occurrence of restenosis. Results The technical success rate was 98.92% (92/93. Pre-treatment stenosis (83.42 ± 9.53% was improved to (21.82 ± 9.86% after stent placement. The difference was statistically significant (t = 3.280, P = 0.002. There were 5 patients (5.56% occurred major periprocedural neurological complications, 3 of them died within 30 days after the procedure. The restenosis rate at 6 months after operation was 19.10% (17/89. Conclusion Symptomatic intracranial arterial stenosis can be treated by Wingspan stenting with high technical success rate. The occurrence of complication is low and short-term efficacy is good. However, further study is needed to investigate long-term effect.

  14. Multilink stent promotes less platelet and leukocyte adhesion than a traditional stainless steel stent : An in vitro experimental study

    NARCIS (Netherlands)

    Amoroso, G; van Boven, AJ; Volkers, C; Crijns, HJGM; van Oeveren, W

    2001-01-01

    Background: Platelet and Leukocyte deposition onto metallic struts can be a crucial factor in the outcome of a coronary stenting procedure. By means of an in vitro, closed-loop circulation model, me aimed to assess blood-stent interaction patterns for a new stainless steel stent (MultiLink, Guidant

  15. Stent assisted angioplasty in intracranial atherosclerotic severe stenoses. Efficacy of CT angiography in evaluation of the stented vessels

    International Nuclear Information System (INIS)

    Our aim was to determine whether CT angiography (CTA) is suitable for the evaluation of patency and in-stent restenoses in small vessel stents for intracranial angioplasty. From June, 2000 to February, 2006, 26 patients received stent-assisted angioplasty for intracranial atherosclerotic lesions. The procedure was successfully performed in all patients. Multi plannar reconstruction (MPR) was evaluated for image quality on three groups with I-E (Internal-External diameter) ratios, as follows: Group A=I-E ratio>0.5 (Possible to evaluate stent lumen, high certainty), Group B=0.31≤I-E ratio≤0.5 (Possible to evaluate stent lumen, low certainty), Group C=I-E ratio≤0.31 (Uninterpretable). We examined the possibility of evaluating the stent lumen, maching the identity with the angiographical findings, and finding a predictor of favorable CTA findings. CTA was performed in 19 patients. It was possible to evaluate the visible stent lumen in 14 patients (73.7%); 10 patients comprised group A, 4 patients group B, 5 patients group C. Nine patients were evaluated with both CTA and angiography after the stenting. CTA findings were identical with angiographical findings in 8 of 9 patients. Stent diameter was associated with CTA findings, all of the patients who received 4.0 mm stents were in group A. The stent lumen may be visualized and evaluated in most stents using CTA, but tend to only be interpretable in the small vessels. (author)

  16. Very late stent thrombosis of bare-metal coronary stent nine years after primary percutaneous coronary intervention

    Directory of Open Access Journals (Sweden)

    Đurić Predrag

    2016-01-01

    Full Text Available Introduction. Stent thrombosis (ST in clinical practice can be classified according to time of onset as early (0–30 days after stent implantation, which is further divided into acute ( 30 days and very late (> 12 months. Myocardial reinfaction due to very late ST in a patient receiving antithrombotic therapy is very rare, and potentially fatal. The procedure alone and related mechanical factors seem to be associated with acute/subacute ST. On the other hand, in-stent neoathero-sclerosis, inflammation, premature cessation of antiplatelet therapy, as well as stent fracture, stent malapposition, un-covered stent struts may play role in late/very late ST. Some findings implicate that the etiology of very late ST of bare-metal stent (BMS is quite different from those following drug-eluting stent (DES implantation. Case report. We presented a 56-year old male with acute inferoposterior ST segment elevation myocardial infarction (STEMI related to very late stent thrombosis, 9 years after BMS implantation, despite antithrombotic therapy. Thrombus aspiration was successfully performed followed by percutaneous coronary intervention (PCI with implantation of DES into the pre-viously implanted two stents to solve the in-stent restenosis. Conclusion. Very late stent thrombosis, although fortu-nately very rare, not completely understood, might cause myocardial reinfaction, but could be successfully treated with thrombus aspiration followed by primary PCI. Very late ST in the presented patient might be connected with neointimal plaque rupture, followed by thrombotic events.

  17. Clinical outcomes and prognosis of patients with stent fracture after successful drug-eluting stent implantation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Soo [Cadiovascular center, Chonnam National University Hospital, Gwangju (Korea, Republic of); Han, Jae Bok; Jang, Seong Joo [Dept. of Radiology, Dongshin University, Naju (Korea, Republic of)

    2014-06-15

    Many studies have suggested that in the era of Drug Eluting Stents (DES) are one of the causes of In-Stent Restenosis (ISR) of Stent Fracture (SF). The present study sought to evaluate clinical characteristics of patients with stent fracture after successful DES implantation. The 4,701 patients were selected for analysis who underwent a follow-up coronary angiography irrespective of ischemic symptoms. The overall incidence of SF was 32 patients(male:female=19:13, Av. age 62.44±9.8 year, 0.68%). Fractures of Sirolimus-Eluting Stents (SES), Paclitaxel-Eluting Stents (PES), Biolimus A9-Eluting Stents (BES), Everolimus-Eluting Etents (EES), Endothelial Progenitor Cell Capture Stent (EPC) and Zotarolimus-Eluting Stents (ZES) are accounted for 19 (59.4%), 9 (28.1%), 2 (6.3%), 1 (3.1%), 1 (3.1%) and 0 (0%) respectively. SF developed in the left Anterior Dscending (LAD) artery in 16 patients (50%) and in complex(type B2, C) lesions in 25 patients (69.4%). Ten patients were treated with heterogenous DES, the rest being treated with either homogenous DES (3 patients), plain old balloon angioplasty (3 patients), or conservative medical treatment (17 patients). None of the patients with SF suffered from cardiac death during a follow-up period of 32.9±12.4 months. The overall rate of DES fracture over up to 3.7 years of follow-up was 0.68% with higher incidence in SES than in PES. SF frequently occurred in the LAD artery and in complex lesions. Of the patients with SF, coronary intervention was performed only when the binary restenosis lesion was significant. During the follow-up, patients with SF have continued on combination antiplatelet therapy. There is a very low rate of major adverse cardiac events(post-detection of SF), especially cardiac death associated with SF.

  18. Air cholangiography in endoscopic bilateral stent-in-stent placement of metallic stents for malignant hilar biliary obstruction

    Science.gov (United States)

    Lee, Jae Min; Lee, Sang Hyub; Jang, Dong Kee; Chung, Kwang Hyun; Park, Jin Myung; Paik, Woo Hyun; Lee, Jun Kyu; Ryu, Ji Kon; Kim, Yong-Tae

    2016-01-01

    Background: Although endoscopic bilateral stent-in-stent (SIS) placement of self-expandable metallic stents (SEMS) is one of the major palliative treatments for unresectable malignant hilar biliary obstruction, post-endoscopic retrograde cholangiopancreatography (ERCP) cholangitis can occur frequently due to inadequate drainage, especially after contrast injection into the biliary tree. The aim of this study is to evaluate the efficacy and safety of air cholangiography-assisted stenting. Methods: This study included 47 patients with malignant hilar biliary obstruction who underwent endoscopic bilateral SEMS placement using the SIS technique. They were divided into two groups, air (n = 23) or iodine contrast (n = 24) cholangiography. We retrospectively compared comprehensive clinical and laboratory data of both groups. Results: There were no significant differences found between the two groups with respect to technical success (87% versus 87.5%, air versus contrast group, respectively), functional success (95% versus 95.2%), 30-day mortality (8.3% versus 8.7%) and stent patency. Post-ERCP adverse events occurred in 5 (21.7%) of the patients in the air group and 8 (33.3%) of the patients in the contrast group. Among these, the rate of cholangitis was significantly lower in the air group (4.8% versus 29.2%, p = 0.048). In multivariate analysis, air cholangiography, technical success and a shorter procedure time were significantly associated with a lower incidence of post-ERCP cholangitis. Conclusions: Air cholangiography-assisted stenting can be a safe and effective method for endoscopic bilateral SIS placement of SEMS in patients with malignant hilar biliary obstruction. PMID:26929781

  19. Mechanical characteristics of self-expandable metallic stents: in vitro study with three types of stress

    International Nuclear Information System (INIS)

    To obtain objective and comparable data for mechanical characteristics of self-expandable metallic stents widely used in the treatment of biliary obstruction. The stents tested were the 6 and 8 mm-band Hanaro spiral stent, Gianturco-Rosch Z stent, Wallstent, Ultraflex stent, and Memotherm stent. Each was subjected to three types of load:point, area, and circular. We analyzed their mechanical characteristics (resistance force, expansile force, and elasticity) according to these three types of stress. With regard to point loads, the Memotherm stent showed the highest resistance force and expansile force. The 8 mm-band Hanaro stent showed the lowest resistance force and the Gianturco-Rosch Z stent and Ultraflex stent showed lower expansile force. With regard to area loads, the Ultraflex stent showed the highest resistance force. The 6 mm-band Hanaro stent, Gianturco-Rosch Z stent, and Ultraflex stent showed higher expansile force. The 8 mm-band Hanaro stent showed the lowest value in both resistance force and expansile force. For circular loads, the Memotherm stent showed the highest resistance force and the Ultraflex stent and Wallstent showed lower value. Under all types of stress, the Hanaro stent and Memotherm stent were completely elastic, and the Ultraflex stent and Wallstent showed a wide gap between resistance force and expansile force. In clinical practice, awareness of the mechanical characteristics of each stent might help in choosing the one which is most suitable, according to type of biliary obstruction. =20

  20. Comparison of Angiographic Outcomes of Side Branch Ostium at Bifurcation Coronary Lesion between Two-stent and One-stent Techniques

    OpenAIRE

    Seo, Jae-Bin; Park, Kyung Woo; Lee, Hae-Young; Kang, Hyun-Jae; Koo, Bon-Kwon; Kim, Sang-Hyun; Kim, Hyo-Soo

    2015-01-01

    Although the favored strategy for coronary bifurcation intervention is stenting main vessel with provisional side branch (SB) stenting, we occasionally use two-stent strategy. The objective of this study was to investigate the angiographic outcome of SB ostium in two-stent group, compared with one-stent group. We analyzed 199 patients with bifurcation lesion who underwent percutaneous coronary intervention (PCI) with drug-eluting stent and follow up angiography. The patients were divided into...

  1. Malignant duodenal obstructions: palliative treatment with covered expandable nitinol stent

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun Chul; Jung, Gyoo Sik; Lee, Sang Hee; Kim, Sung Min; Oh, Kyung Seung; Huh, Jin Do; Cho, Young Duk [College of Medicine, Kosin Univ, Pusan (Korea, Republic of); Song, Ho Young [College of Medicine, Ulsan Univ., Seoul (Korea, Republic of)

    2002-04-01

    To evaluate the feasibility and clinical effectiveness of using a polyurethane-covered expandable nitinol stent in the palliative treatment of malignant duodenal obstruction. Under fluoroscopic guidance, a polyurethane-covered expandable nitinol stent was placed in 12 consecutive patients with malignant duodenal obstructions. All presented with severe nausea and recurrent vomiting. The underlying causes of obstruction were duodenal carcinoma (n=4), pancreatic carcinoma (n=4), gall bladder carcinoma (n=2), distal CBD carcinoma (n=1), and uterine cervical carcinoma (n=1). The sites of obstruction were part I (n=1), part II (n=8), and III (n=3). Due to pre-existing jaundice, eight patients with part II obstructions underwent biliary decompression prior to stent placement. An introducer sheath with a 6-mm outer diameter and stents 16 mm in diameter were employed, and to place the stent, and after-loading technique was used. Stent placement was technically successful in ten patients, and no procedural complications occuured. In one of two patients in whom there was technical failure, and in whom the obstructions were located in part III, the stent was placed transgastrically. Stent migration occurred in one patient four days after the procedure, and treatment involved the palcement of a second, uncovered, nitinol stent. After stent placement, symptoms improved in all patients. During follow-up, obstructive symptoms due to stent stenosis (n=1), colonic obstruction (n=1), and multiple small bowel obstruction (n=1) recurred in three patients. Two of these were treated by placing additional stents in the duodenum and colon, respectively. One of the eight patients in whom a stent was placed in the second portion of the duodenum developed jaundice. The patients died a mean 14 (median, 9) weeks after stent placement. The placement of a polyurethane-covered expandable nitinol stent seems to be technically feasible, safe and effective for the palliative treatment of malignant

  2. Mechanisms and Patterns of Intravascular Ultrasound In-Stent Restenosis Among Bare Metal Stents and First- and Second-Generation Drug-Eluting Stents.

    Science.gov (United States)

    Goto, Kosaku; Zhao, Zhijing; Matsumura, Mitsuaki; Dohi, Tomotaka; Kobayashi, Nobuaki; Kirtane, Ajay J; Rabbani, LeRoy E; Collins, Michael B; Parikh, Manish A; Kodali, Susheel K; Leon, Martin B; Moses, Jeffrey W; Mintz, Gary S; Maehara, Akiko

    2015-11-01

    The most common causes of in-stent restenosis (ISR) are intimal hyperplasia and stent under expansion. The purpose of this study was to use intravascular ultrasound (IVUS) to compare the ISR mechanisms of bare metal stents (BMS), first-generation drug-eluting stents (DES), and second-generation DES. There were 298 ISR lesions including 52 BMS, 73 sirolimus-eluting stents, 52 paclitaxel-eluting stents, 16 zotarolimus-eluting stents, and 105 everolimus-eluting stent. Mean patient age was 66.6 ± 1.1 years, 74.2% were men, and 48.3% had diabetes mellitus. BMS restenosis presented later (70.0 ± 66.7 months) with more intimal hyperplasia compared with DES (BMS 58.6 ± 15.5%, first-generation DES 52.6 ± 20.9%, second-generation DES 48.2 ± 22.2%, p = 0.02). Although reference lumen areas were similar in BMS and first- and second-generation DES, restenotic DES were longer (BMS 21.8 ± 13.5 mm, first-generation DES 29.4 ± 16.1 mm, second-generation DES 32.1 ± 18.7 mm, p = 0.003), and stent areas were smaller (BMS 7.2 ± 2.4 mm(2), first-generation DES 6.1 ± 2.1 mm(2), second-generation DES 5.7 ± 2.0 mm(2), p Stent fracture was seen only in DES (first-generation DES 7 [5.0%], second-generation DES 8 [7.4%], p = 0.13). In conclusion, restenotic first- and second-generation DES were characterized by less neointimal hyperplasia, smaller stent areas, longer stent lengths, and more stent fractures than restenotic BMS.

  3. Alternative Asymmetric Stochastic Volatility Models

    NARCIS (Netherlands)

    M. Asai (Manabu); M.J. McAleer (Michael)

    2010-01-01

    textabstractThe stochastic volatility model usually incorporates asymmetric effects by introducing the negative correlation between the innovations in returns and volatility. In this paper, we propose a new asymmetric stochastic volatility model, based on the leverage and size effects. The model is

  4. Metallic stent and stereotactic conformal radiotherapy for hilar cholangiocarcinoma

    International Nuclear Information System (INIS)

    Objective: To evaluate the effect of metallic stent combined with stereotactic conformal radiotherapy (SCRT) for hilar cholangiocarcinoma. Methods: Fifty-four patients with hilar cholangiocarcinoma were analyzed, including 31 treated with stent plus stereotactic conformal radiotherapy (combined group) and 23 with metallic stent alone (control group). Results: The mean survival time of combined group was 11.1 ± 4.6 months, compared with 5.1 ± 2.8 months of the control group, giving a significant difference between the two groups (P<0.01). Conclusion: The combination of metallic stent and stereotactic conformal radiotherapy is more effective than metallic stent alone for unresectable hilar cholangiocarcinoma. (authors)

  5. Treatment Approaches to Urinary Stones Caused by Forgotten DJ Stents

    Directory of Open Access Journals (Sweden)

    Ergun Alma

    2015-03-01

    Full Text Available Ureteral DJ stents have been used widely for years in urology practice. With increased use, complications have been increased and forgotton stents have started to cause problems. The most common complications are early pain and irritative symptoms. Late complications are bacterial colonization and stone formation because of the biofilm covering the stents. Treatment for a forgotten stent varies on many factors, such as stent localization and stone formation. In this article, we aimed to discuss our clinic approach on two different cases in light to current literature. [Cukurova Med J 2015; 40(Suppl 1: 58-63

  6. Fast virtual stenting with deformable meshes: application to intracranial aneurysms.

    Science.gov (United States)

    Larrabide, Ignacio; Radaelli, Alessandro; Frangi, Alejandro

    2008-01-01

    Intracranial stents are medical devices that are becoming increasingly popular in the treatment of intracranial aneurysms. A methodology that predicts the released stent configuration prior to intervention has the potential to support the physician in the selection of the optimal approach for a specific patient. This paper proposes a fast virtual stenting technique based on constrained simplex deformable models that is able to virtually release stents in arbitrarily shaped vessel and aneurysm models. The technique effectively embeds the geometrical properties of the stent (cell design, strut size and shape and angles between struts) and achieves favorable execution times of the order of one minute.

  7. Gastrointestinal stenting: Current status and imaging features.

    Science.gov (United States)

    Malgras, B; Lo Dico, R; Pautrat, K; Dohan, A; Boudiaf, M; Pocard, M; Soyer, P

    2015-06-01

    The use of stents in the gastrointestinal tract has been subjected to major changes. Initially, the use of stents was restricted to malignant strictures in patients with metastatic disease. But thanks to reduction of the morbidity and mortality rates, they are now used with curative intention and in patients with benign diseases after careful selection. However, for patients presenting with colon obstruction due to an advanced colon carcinoma, the mortality and morbidity are still high. The purpose of this review is to provide an overview of indications, techniques and further developments of the stents in the gastrointestinal tract and to highlight the predominant role of multidetector row computed tomography (MDCT) in the detection of potential complications. PMID:25953525

  8. Engineered Asymmetric Synthetic Vesicles

    Science.gov (United States)

    Lu, Li; Chiarot, Paul

    2013-11-01

    Synthetic vesicles are small, fluid-filled spheres that are enclosed by a bilayer of lipid molecules. They can be used as models for investigating membrane biology and as delivery vehicles for pharmaceuticals. In practice, it is difficult to simultaneously control membrane asymmetry, unilamellarity, vesicle size, vesicle-to-vesicle uniformity, and luminal content. Membrane asymmetry, where each leaflet of the bilayer is composed of different lipids, is of particular importance as it is a feature of most natural membranes. In this study, we leverage microfluidic technology to build asymmetric vesicles at high-throughput. We use the precise flow control offered by microfluidic devices to make highly uniform emulsions, with controlled internal content, that serve as templates to build the synthetic vesicles. Flow focusing, dielectrophoretic steering, and interfacial lipid self-assembly are critical procedures performed on-chip to produce the vesicles. Fluorescent and confocal microscopy are used to evaluate the vesicle characteristics.

  9. Asymmetric black dyonic holes

    Directory of Open Access Journals (Sweden)

    I. Cabrera-Munguia

    2015-04-01

    Full Text Available A 6-parametric asymptotically flat exact solution, describing a two-body system of asymmetric black dyons, is studied. The system consists of two unequal counterrotating Kerr–Newman black holes, endowed with electric and magnetic charges which are equal but opposite in sign, separated by a massless strut. The Smarr formula is generalized in order to take into account their contribution to the mass. The expressions for the horizon half-length parameters σ1 and σ2, as functions of the Komar parameters and of the coordinate distance, are displayed, and the thermodynamic properties of the two-body system are studied. Furthermore, the seven physical parameters satisfy a simple algebraic relation which can be understood as a dynamical scenario, in which the physical properties of one body are affected by the ones of the other body.

  10. Drug-eluting or bare-metal stents for large coronary vessel stenting? The BASKET-PROVE (PROspective Validation Examination) trial: Study protocol and design

    DEFF Research Database (Denmark)

    Pfisterer, M.; Bertel, O.; Bonetti, P.O.;

    2008-01-01

    Background Based on a subgroup analysis of 18-month BAsel Stent Kosten Effektivitats Trial (BASKET) outcome data, we hypothesized that very late (>12 months) stent thrombosis occurs predominantly after drug-eluting stent implantation in large native coronary vessel stenting. Methods To prove...... stent use in patients with large native vessel stenting. The 2-year death/myocardial infarction-as well as target vessel revascularization-and bleeding rates in these patients with a first-versus second-generation drug-eluting stent should demonstrate the benefit or harm of these stents compared...

  11. Use of PTFE Stent Grafts for Hemodialysis-related Central Venous Occlusions: Intermediate-Term Results

    International Nuclear Information System (INIS)

    Purpose: To assess the safety and effectiveness of a polytetrafluoroethylene (PTFE) encapsulated nitinol stents (Bard Peripheral Vascular, Tempe, AZ) for treatment of hemodialysis-related central venous occlusions. Materials and Methods: Study design was a single-center nonrandomized retrospective cohort of patients from May 2004 to August 2009 for a total of 64 months. There were 14 patients (mean age 60 years, range 50–83 years; 13 male, 1 female). All patients had autogenous fistulas. All 14 patients had central venous occlusions and presented with clinical symptoms of the following: extremity swelling (14%, 2 of 14), extremity and face swelling (72%, 10 of 14), and face swelling/edema (14%, 2 of 14). There was evidence of access dysfunction with decreased access flow in 36% (5 of 14) patients. There were prior interventions or previous line placement at the site of the central venous lesion in all 14 patients. Results were assessed by recurrence of clinical symptoms and function of the access circuit (National Kidney Foundation recommended criteria). Results: Sixteen consecutive straight stent grafts were implanted in 14 patients. Average treated lesion length was 5.0 cm (range, 0.9–7 cm). All 14 patients had complete central venous occlusion (100% stenosis). The central venous occlusions were located as follows: right subclavian and brachiocephalic vein (21%, 3 of 14), right brachiocephalic vein (36%, 5 of 14), left brachiocephalic vein (36%, 5 of 14), and bilateral brachiocephalic vein (7%, 1 of 14). A total of 16 PTFE stent grafts were placed. Ten- or 12-mm-diameter PTFE stent grafts were placed. The average stent length was 6.1 cm (range, 4–8 cm). Technical (deployment), anatomic (<30% residual stenosis), clinical (resolution of symptoms), and hemodynamic (resolution of access dysfunction) success were 100%. At 3, 6, and 9 months, primary patency of the treated area and access circuit were 100% (14 of 14). Conclusions: This PTFE encapsulated stent

  12. Brachial access technique for aortoiliac stenting revisited

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We report a modified technique to perform iliac artery stenting through the brachial artery access. A 6F Brite tip sheath (Cordis, Jonhson & Jonhson Medical, Miami Lakes, FL, USA) is inserted into either brachial artery and a standard 4F Judkins Right diagnostic catheter was inserted over a 260 cm 0.038" Terumo Stiff wire (Terumo Corp, Tokyo, Japan) through the sheath. The catheter is navigated down to the aortic bifurcation, and after selecting the common iliac artery ostium, the wire is navigated through the lesion and advanced to the ipsilateral superficial femoral arteries. The catheter should be then moved forward over the wires beyond the lesion and the Terumo guidewire is replaced by two 0.038" 260 cm Supracor wires (Boston Scientific Corporation, San Jose, CA, USA). In order to facilitate advancement of the stent without risk of dislodgement as well as to check the position with low contrast dose injection, a 6 F (or 7F if large stent is selected) 90cm Shuttle Flexor introducer long sheath (Cook Group, Bloomington, IN, USA) should be advanced over the Supracor wire until it reaches the common iliac artery ostium. A road-map technique can be used to check the ostium position in order to properly deploy the selected stent. This technique promises to be safe and effective offering more support than guiding catheter technique; moreover it reduces the stress on the arterial vessel at the subclavian site and enables a stiff balloon or stent catheter to be advanced even through a very elongated and calcified aorta without the risk of stent dislodgement.

  13. Management of complications during percutaneous implementation of biliary stents

    International Nuclear Information System (INIS)

    Objective: To retrospectively analyze the complications and management of complications during percutaneous implementation of biliary stents in 17 patients. Methods: Percutaneous biliary drainage and implementation of biliary stents for malignant biliary obstruction under fluoroscopic guidance was performed in 64 patients. 17 cases developed complications. Bradycardia and hypotension was seen in 5 cases, slipping of the stent into the duodenum in 1, bile duct perforation in 2, the fine guidewire broken in the hepatic parenchyma in 2, malposition of the stent in 3, hepato-renal failure leading to hemorrhage in 2, exchanging guidewire broken in the duodenum in 1, and balloon broken leading to stent dislocation in 1, respectively. Results: Bradycardia and hypotension in the 5 cases was treated medically and the procedure was interrupted. Slipping of the stent into the duodenum was passed off spontaneously. Broken of the fine guidewire in the liver did not present any complaints until the death of the patients. Perforation of bile duct was treated conservatively with a clinical successful outcome. Malposition of the stent was treated by reimplementation of shorter stents. The broken exchanging guidewire in the duodenum during implementation was removed with the gastroscope. The hepato-renal failure leading to hemorrhage had poor prognosis. The broken balloon caused stent dislocation was treated by reimplementation of stent. Conclusion: Percutaneous implementation of stent is effective and safe for elderly patients with proximal stenosis of the biliary tract. However, one must be very careful to avoid the complications

  14. Fast Virtual Stenting with Active Contour Models in Intracranical Aneurysm.

    Science.gov (United States)

    Zhong, Jingru; Long, Yunling; Yan, Huagang; Meng, Qianqian; Zhao, Jing; Zhang, Ying; Yang, Xinjian; Li, Haiyun

    2016-02-15

    Intracranial stents are becoming increasingly a useful option in the treatment of intracranial aneurysms (IAs). Image simulation of the releasing stent configuration together with computational fluid dynamics (CFD) simulation prior to intervention will help surgeons optimize intervention scheme. This paper proposed a fast virtual stenting of IAs based on active contour model (ACM) which was able to virtually release stents within any patient-specific shaped vessel and aneurysm models built on real medical image data. In this method, an initial stent mesh was generated along the centerline of the parent artery without the need for registration between the stent contour and the vessel. Additionally, the diameter of the initial stent volumetric mesh was set to the maximum inscribed sphere diameter of the parent artery to improve the stenting accuracy and save computational cost. At last, a novel criterion for terminating virtual stent expanding that was based on the collision detection of the axis aligned bounding boxes was applied, making the stent expansion free of edge effect. The experiment results of the virtual stenting and the corresponding CFD simulations exhibited the efficacy and accuracy of the ACM based method, which are valuable to intervention scheme selection and therapy plan confirmation.

  15. Transanal stent in anterior resection does not prevent anastomotic leakage

    DEFF Research Database (Denmark)

    Bülow, Steffen; Bulut, O; Christensen, Ib Jarle;

    2006-01-01

    OBJECTIVE: A defunctioning transanal stent may theoretically reduce the leakage rate after anterior rectal resection. We present a randomized open study with the aim of comparing the leakage rate after anterior resection with a loop ileostomy, a transanal stent, both or neither. PATIENTS...... completion of the operation the patients were randomized in two groups with and without a transanal stent. RESULTS: A clinically significant leakage was diagnosed in 25 patients (13%). No significant difference was found 17 of 98 patients with a stent and 8 of 96 without (P = 0.09), or in 9 of 44 ileostomy...... patients with a stent and in 3 of 45 without (P = 0.07). Several leaks over a short time led to an interim analysis after inclusion of 194 of 448 planned patients. The analysis showed no significant protective effect of the stent, and more leakages in the stent group, although not statistically significant...

  16. Experimental Study and Design of Balloon expandable Endovascular Stent Expansion

    Institute of Scientific and Technical Information of China (English)

    WANG Yue-xuan; YI Hong; NI Zhong-hua

    2005-01-01

    The application background and experimental research overview of medical endovascular stent are presented. Based on the analytical comparison of the current research achievements, the life cycle of medical endovascular stent is pointed out and the characteristics of stent expansion in the life cycle are emphasized on.The experimental scheme of in vitro stent expansion based on the machine vision technology in LabVIEW is presented. The selection and usage of the chosen component devices and design of measurement program for experiment are expatiated. A special drug-loading stent was expanded on the assembled platform of selected equipments and experimental results were analyzed. The experimental scheme presented in the paper provides powerful experimental support for the optimization of stent design and computer simulation of stent expansion by the finite element analysis.

  17. Surface conditioning of 316LVM slotted tube cardiovascular stents.

    Science.gov (United States)

    Raval, Ankur; Choubey, Animesh; Engineer, Chhaya; Kothwala, Devesh

    2005-01-01

    The surface quality of coronary stents has a significant influence on its biocompatibility. Therefore, surface polishing is of paramount importance in the production and application of stents. In the present study, electropolishing is performed on 316LVM steel slotted tube coronary stents. Additionally, acid pickling, as a pretreatment of electropolishing, is also conducted. Gravimetric analysis of the stents (weight loss and strut width change) in the process of acid pickling and electropolishing are done. Qualitative roughness measurements are made to evaluate the stent surface. Electropolished stents are passivated causing chromium enrichment on the surface of the material, thereby enhancing its corrosion resistance. Passivated and electropolished samples are examined using energy dispersive spectrometry. Balloon expanded and crimped profiles of the passivated stents are qualitatively analyzed. PMID:15613380

  18. Spontaneous Solitaire™ AB Thrombectomy Stent Detachment During Stroke Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Akpinar, Suha, E-mail: akpinarsuha@hotmail.com; Yilmaz, Guliz, E-mail: glz.yilmaz@hotmail.com [Near East University Hospital, Department of Radiology, Faculty of Medicine (Turkey)

    2015-04-15

    Spontaneous Solitaire™ stent retriever detachment is a rarely defined entity seen during stroke treatment, which can result in a disastrous clinical outcome if it cannot be solved within a critical stroke treatment time window. Two solutions to this problem are presented in the literature. The first is to leave the stent in place and apply angioplasty to the detached stent, while the second involves surgically removing the stent from the location at which it detached. Here, we present a case of inadvertent stent detachment during stroke treatment for a middle cerebral artery M1 occlusion resulting in progressive thrombosis. The detached stent was removed endovascularly by another Solitaire stent, resulting in the recanalization of the occluded middle cerebral artery.

  19. Role of stents and laser therapy in biliary strictures

    Science.gov (United States)

    Chennupati, Raja S.; Trowers, Eugene A.

    2001-05-01

    The most frequent primary cancers causing malignant obstructive jaundice were pancreatic cancer (57%), hilar biliary cancer (19% including metastatic disease), nonhilar biliary cancer (14%) and papillary cancer (10%). Endoscopic stenting has widely replaced palliative surgery for malignant biliary obstruction because of its lower risk and cost. Self-expandable metal stents are the preferred mode of palliation for hilar malignancies. Plastic stents have a major role in benign biliary strictures. Major complications and disadvantages associated with metallic stents include high cost, cholangitis. malposition, migration, unextractability, and breakage of the stents, pancreatitis and stent dysfunction. Dysfunction due to tumor ingrowth can be relieved by thermal methods (argon plasma coagulator therapy). We present a concise review of the efficacy of metallic stents for palliation of malignant strictures.

  20. Experiment of new compliance covered endovascular stent in sheep model%新型高柔顺主动脉覆膜支架实验研究

    Institute of Scientific and Technical Information of China (English)

    王韧; 韩晓峰; 杨帆; 孙立忠; 黄连军; 徐志伟; 杜月河; 贾莲; 郑斯宏

    2014-01-01

    目的 探讨新型高柔顺主动脉覆膜支架在动物模型中使用的安全性和可靠性.方法 12只绵羊分为2组,每组6只,分别进行胸主动脉覆膜支架实验和腹主动脉覆膜支架实验.10 mm人工血管与绵羊腹主动脉吻合,然后经人工血管植入输送器和支架,在胸主动脉释放支架.存活30d后行胸主动脉造影,观察支架位置、形态;然后处死绵羊,进行大体解剖和病理检查.结果 所有支架均释放在所需位置,术中造影无支架移位及内漏.胸主动脉支架组有1只羊术后无法站立,术后5d死亡,尸体解剖可见支架部位血管腔内血栓形成,堵塞管腔.腹主动脉支架组有1只羊术后无法站立,术后30 d后处死,尸体解剖同样发现支架部位血管腔内血栓形成,堵塞管腔.其余羊均术后即可站立,正常活动,饮食无异常.1个月后造影,支架部位管腔通畅,支架固定在释放位置,无移位、内漏及造影剂外漏.病理检查结果证实:植入的支架与血管结合紧密,支架内壁组织光滑.结论 新型高柔顺主动脉覆膜支架在动物实验中表现了良好性能,具有安全性和可靠性.%Objective In order to test feasibility and security of new compliance covered endovascular stent in sheep model.Methods 12 sheeps were divided into 2 groups:thoracic aortic stent group and abdominal aortic stent group.10 mm diameters of vascular prosthesis was end-to-side anastomosed with abdominal aorta of the sheep.Stents were transported through vascular prosthesis into thoracic aorta of the sheep.The stents were deployed in desired position of thoracic aorta.30 days later,aortogram were performed to observe position and shape of the stents.Then,the sheep were euthanized,gross and histopathologic study were executed.Results All stent were successfully deployed,no stent shifting and endoleak were observed during aortagram 30 days after operation.1 sheep died of thrombosis of the thoracic aortic stent at 5 day

  1. Development of an abdominal aortic aneurysm model for stent-graft insertion

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Hyung; Lee, Jong Heon; Shin, Dong Ik; Sung, Kyu Bo; Ko, Gi Young; Lim, Jin Oh [College of Medicine, Univ. of Ulsan, Seoul (Korea, Republic of); Kim, Si Hoon [S and G Biotech Research Institute, Seoul (Korea, Republic of)

    2002-03-01

    To determine the efficacy of an abdominal aortic aneurysm model for stent-graft placement. The model consists of two parts, the heart and the vascular system. A peristaltic pump and a solenoid valve were used to simulate a pulsatile flow from the heart. A ball-shaped piece of clay was placed inside a square box and liquid silicone was poured. After the silicone was formed, the clay was removed and a silicone tube was used to connect the heart model and the aneurysm model. The silicone tube was also used to simulate the iliac arteries and one end of the artery was clampled and the other one was extended to water bath. Water at 37 .deg. C was circulated through the model, and the pressure at the thoracic aorta, aneurysm and iliac artery was measured with the outlet valve opening at 25, 50, and 100% before and after stent-graft placement. The liquid pressure measurements were 253/252, 271/162 and 264/166 mmHg at the thoracic aorta, aneurysm and iliac artery, respectively, when the outlet was 100% open. They were 173/121, 145/99, 145/106 mmHg when the outlet was 50% open, and 35/28, 61/44, 24/22 mmHg when it was 25% open. After placement of the stent-graft, the pressure measurements were 170/128, and 167/128 mmHg, respectively. Since it was easy to produce, the model was useful for in-vitro stent-graft testing, and a wide range of pressure could be applied.

  2. Lung tissue flap repairs esophagus defection with an inner chitosan tube stent

    Institute of Scientific and Technical Information of China (English)

    Gang Chen; Wen-Jun Shi

    2009-01-01

    AIM:To repair the partial esophagus defect with a chitosan stent, a new esophageal prosthesis made of pulmonary tissue with vascular pedicle. METHODS:Fifteen Japanese big ear white rabbits were divided into experimental group ( n = 10) and control group ( n = 5). Esophagus defect in rabbits of experimental group was repaired using lung tissue flap with a chitosan tube stent, gross and histological appearance was observed at week 2, 4 and 8 after operation, and barium sulphate X-ray screen was performed at week 10 after operation. Esophagus defect of rabbits in control group was repaired using lung tissue flap with no chitosan tube stent, gross and histological appearance was observed at week 2, 4 and 8 after operation, and barium sulphate X-ray screen was performed at week 10 after operation. RESULTS:In the experimental group, 6 rabbits survived for over two weeks, the lung tissue flap healed esophageal defec t ion, and squamous metaplasia occurred on the surface of lung tissue flap. At week 10 after operation, barium sulphate examination found that barium was fluent through the esophagus with no stricture or back stream, the creeping was good. In the control group, 4 rabbits survived for two weeks, the lung tissue flap healed esophageal defection with fibrous tissue hyperplasia, barium sulphate examination found that barium was fluent through the esophagus with a slight stricture or back stream, and the creeping was not good at week 10 after operation.CONCLUSION:Esophagus defect can be repaired using lung tissue flap with an inner chitosan tube stent.

  3. Effect of Shuxinyin (舒心饮) on In-Stent Restenosis after Coronary Artery Stenting

    Institute of Scientific and Technical Information of China (English)

    王显; 林钟香; 葛均波; 刘旭; 何燕; 张振贤; 沈琳

    2002-01-01

    Objective: To evaluate the effect of anti-platelet regimens and it's combination with Shuxinyin (SXY, 舒心饮,) on in-stent restenosis after stent implantation. Methods: Forty-four patients with successful stent implantation in a coronary artery were randomly assigned to the treated group (n=20) and the control group (n=24). The treated group received: SXY and anti-platelet therapy. The control group were treated with anti-platelet regimens only. Platelet activation was assessed before and immediately after the stenting by flow cytometry, the expression of P-selectin (CD62P) and glycoprotein(GP) Ⅱb/Ⅲa receptor. It was reassessed on the 30th day after stenting. Plasma fibrinogen (Fg) and C-reaction protein (CRP) were measured by biuret and laser scattering turbidimetry respectively at the same time. Observation was made on the scoring of the symptoms of Qi deficiency syndrome, Qi-Yin deficiency syndrome and blood stasis syndrome in the two groups. Differences between groups were compared. Results: Compared with the control group, combination with SXY and anti-platelet therapy was remarkable in reducing plasma CRP (P<0.05), and also with the tendency to decrease plasma Fg, GPⅡb/Ⅲa and CD62P. It could also evidently decrease the scoring of Qi-Yin deficiency syndrome, Qi deficiency syndrome and blood stasis syndrome after stenting (P<0.05, 0.01, 0.01) respectively. Follow-up survey found 40% relapse of angina pectoris with 4 cases of in-stent restenosis proved by angiography in the treated group. But the relapse of angina pectoris in the control group was 67% with 2 cases of myocardial infarction (MI), 7 cases of in-stent restenosis proved by angiography and one death. Conclusions: Combination with SXY and anti-platelet regimens can prevent stent thrombosis and in-stent restenosis after stent implantation, and it seems superior to anti-platelet therapy only.

  4. Optimal Stent Expansion by Stent Balloon Multiple Inflation at Nominal Pressure in Resistant Lesions: A New Technique

    Directory of Open Access Journals (Sweden)

    Amir Hossein Khosh Nasab

    2015-09-01

    Full Text Available Introduction: This study aimed to evaluate the effects of four-time inflation of the stent balloon at nominal pressure on optimal stent expansion in resistant lesions. Materials and Methods: This interventional study was conducted on 39 patients with coronary artery lesions, in whom Zotarolimus-eluting stents (N=20, Paclitaxel-eluting stents (N=11 and other stents (N=8 were deployed four times at nominal inflation pressure and increased inflation times (5, 15, 30 and 45 seconds. After the deployments, enhanced stent visualization imaging technique (IC stent was used to assess stent placement and artery expansion. Results: In this study, early success rate was estimated at 79.5% using the enhanced stent visualization imaging technique. In addition, major adverse cardiac event (MACE was determined at 2.6%. Also, conventional methods resulted in lower success rate and higher MACE in resistant lesions. Conclusion: According to the results of this study, four-time stent balloon inflation at nominal pressure could allow adequate stent expansion in resistant lesions leading to lower MACE.

  5. A novel balloon assisted two-stents telescoping technique for repositioning an embolized stent in the pulmonary conduit.

    Science.gov (United States)

    Kobayashi, Daisuke; Gowda, Srinath T; Forbes, Thomas J

    2014-08-01

    A 9-year-old male, with history of pulmonary atresia and ventricular septal defect, status post complete repair with a 16 mm pulmonary homograft in the right ventricular outflow tract (RVOT) underwent 3110 Palmaz stent placement for conduit stenosis. Following deployment the stent embolized proximally into the right ventricle (RV). We undertook the choice of repositioning the embolized stent into the conduit with a transcatheter approach. Using a second venous access, the embolized stent was carefully maneuvered into the proximal part of conduit with an inflated Tyshak balloon catheter. A second Palmaz 4010 stent was deployed in the distal conduit telescoping through the embolized stent. The Tyshak balloon catheter was kept inflated in the RV to stabilize the embolized stent in the proximal conduit until it was successfully latched up against the conduit with the deployment of the overlapping second stent. One year later, he underwent Melody valve implantation in the pre-stented conduit relieving conduit insufficiency. This novel balloon assisted two-stents telescoping technique is a feasible transcatheter option to secure an embolized stent from the RV to the RVOT.

  6. Branding of vascular surgery.

    Science.gov (United States)

    Perler, Bruce A

    2008-03-01

    The Society for Vascular Surgery surveyed primary care physicians (PCPs) to understand how PCPs make referral decisions for their patients with peripheral vascular disease. Responses were received from 250 PCPs in 44 states. More than 80% of the respondents characterized their experiences with vascular surgeons as positive or very positive. PCPs perceive that vascular surgeons perform "invasive" procedures and refer patients with the most severe vascular disease to vascular surgeons but were more than twice as likely to refer patients to cardiologists, believing they are better able to perform minimally invasive procedures. Nevertheless, PCPs are receptive to the notion of increasing referrals to vascular surgeons. A successful branding campaign will require considerable education of referring physicians about the totality of traditional vascular and endovascular care increasingly provided by the contemporary vascular surgical practice and will be most effective at the local grassroots level.

  7. Computational simulation of platelet interactions in the initiation of stent thrombosis due to stent malapposition

    Science.gov (United States)

    Chesnutt, Jennifer K. W.; Han, Hai-Chao

    2016-02-01

    Coronary stenting is one of the most commonly used approaches to open coronary arteries blocked due to atherosclerosis. Stent malapposition can induce thrombosis but the microscopic process is poorly understood. The objective of this study was to determine the platelet-level process by which different extents of stent malapposition affect the initiation of stent thrombosis. We utilized a discrete element model to computationally simulate the transport, adhesion, and activation of thousands of individual platelets and red blood cells during thrombus initiation in stented coronary arteries. Simulated arteries contained a malapposed stent with a specified gap distance (0, 10, 25, 50, or 200 μm) between the struts and endothelium. Platelet-level details of thrombus formation near the proximal-most strut were measured during the simulations. The relationship between gap distance and amount of thrombus in the artery varied depending on different conditions (e.g., amount of dysfunctional endothelium, shear-induced activation of platelets, and thrombogenicity of the strut). Without considering shear-induced platelet activation, the largest gap distance (200 μm) produced no recirculation and less thrombus than the smallest two gap distances (0 and 10 μm) that created recirculation downstream of the strut. However, with the occurrence of shear-induced platelet activation, the largest gap distance produced more thrombus than the two smallest gap distances, but less thrombus than an intermediate gap distance (25 μm). A large gap distance was not necessarily the most thrombogenic, in contrast to implications of some computational fluid dynamics studies. The severity of stent malapposition affected initial stent thrombosis differently depending on various factors related to fluid recirculation, platelet trajectories, shear stress, and endothelial condition.

  8. Computational simulation of platelet interactions in the initiation of stent thrombosis due to stent malapposition

    Science.gov (United States)

    Chesnutt, Jennifer K W; Han, Hai-Chao

    2016-01-01

    Coronary stenting is one of the most commonly used approaches to open coronary arteries blocked due to atherosclerosis. Stent malapposition can induce thrombosis but the microscopic process is poorly understood. The objective of this study was to determine the platelet-level process by which different extents of stent malapposition affect the initiation of stent thrombosis. We utilized a discrete element model to computationally simulate the transport, adhesion, and activation of thousands of individual platelets and red blood cells during thrombus initiation in stented coronary arteries. Simulated arteries contained a malapposed stent with a specified gap distance (0, 10, 25, 50, or 200 μm) between the struts and endothelium. Platelet-level details of thrombus formation near the proximal-most strut were measured during the simulations. The relationship between gap distance and amount of thrombus in the artery varied depending on different conditions (e.g., amount of dysfunctional endothelium, shear-induced activation of platelets, and thrombogenicity of the strut). Without considering shear-induced platelet activation, the largest gap distance (200 μm) produced no recirculation and less thrombus than the smallest two gap distances (0 and 10 μm) that created recirculation downstream of the strut. However, with the occurrence of shear-induced platelet activation, the largest gap distance produced more thrombus than the two smallest gap distances, but less thrombus than an intermediate gap distance (25 μm). A large gap distance was not necessarily the most thrombogenic, in contrast to implications of some computational fluid dynamics studies. The severity of stent malapposition affected initial stent thrombosis differently depending on various factors related to fluid recirculation, platelet trajectories, shear stress, and endothelial condition. PMID:26790093

  9. Biliary metal stents are superior to plastic stents for preoperative biliary decompression in pancreatic cancer

    OpenAIRE

    Decker, Christopher; Christein, John D.; Phadnis, Milind A.; Mel Wilcox, C.; Varadarajulu, Shyam

    2011-01-01

    Background It is unclear whether plastic or metal stents are more suitable for preoperative biliary decompression in pancreatic cancer. The objective of this study was to compare the rate of endoscopic reinterventions in patients with pancreatic cancer undergoing plastic or self-expandable metal stent (SEMS) placements for preoperative biliary decompression. Methods This was a retrospective study of all patients with obstructive jaundice secondary to pancreatic head cancer who underwent their...

  10. Post-metallic stent placement bleeding caused by stent-induced ulcers

    Institute of Scientific and Technical Information of China (English)

    Chun-Tao Wai; Christopher Khor; Siew-Eng Lim; Khek-Yu Ho

    2005-01-01

    Placement of self-expandable metal stents (SEMS) is an effective mode of palliative treatment for patients with malignant gastrointestinal obstruction. Gastrointestinal mucosal bleeding complicates about 5% of placement of SEMS but is not well described. We report three cases of gastrointestinal bleeding post-SEMS placement and suggest that bleeding is caused by direct mucosal infringement by the sharp edges of the ends of the stents.

  11. Stent Thrombosis is the Primary Cause of ST-Segment Elevation Myocardial Infarction following Coronary Stent Implantation

    DEFF Research Database (Denmark)

    Kristensen, Søren Lund; Galløe, Anders M; Thuesen, Leif;

    2014-01-01

    Background: The widespread use of coronary stents has exposed a growing population to the risk of stent thrombosis, but the importance in terms of risk of ST-segment elevation myocardial infarctions (STEMIs) remains unclear. Methods: We studied five years follow-up data for 2,098 all-comer patients...... treated with coronary stents in the randomized SORT OUT II trial (mean age 63.6 yrs. 74.8% men). Patients who following stent implantation were readmitted with STEMI were included and each patient was categorized ranging from definite-to ruled-out stent thrombosis according to the Academic Research...... Consortium definitions. Multivariate logistic regression was performed on selected covariates to assess odds ratios (ORs) for definite stent thrombosis. Results: 85 patients (4.1%), mean age 62.7 years, 77.1% men, were admitted with a total of 96 STEMIs, of whom 60 (62.5%) had definite stent thrombosis...

  12. Topic controversies in the endoscopic management of malignant hilar strictures using metal stent: side-by-side versus stent-in-stent techniques.

    Science.gov (United States)

    Moon, Jong Ho; Rerknimitr, Rungsun; Kogure, Hirofumi; Nakai, Yousuke; Isayama, Hiroyuki

    2015-09-01

    Endoscopic management of unresectable hilar malignant biliary stricture (MBS) is currently challenging, and the best approach is still controversial. Liver volume is the key to adequate biliary drainage in hilar MBS and multiple stenting is mandatory to drain over 50% of liver volume in most cases. The self-expandable metallic stent (SEMS) has shown superior patency to plastic stents in recent reports. There are two methods of multiple stenting for hilar MBS: stent-in-stent (SIS) and side-by-side (SBS). Advantages of SIS include multiple SEMS placement in one stent caliber at the common bile duct (CBD), which is considered physiologically ideal. The through-the-mesh (TTM) technique with guidewires and the SEMS delivery system can be technically difficult in SIS, although the recent development of dedicated SEMSs having a loose portion facilitating the TTM technique makes SIS technically feasible both at stent deployment and re-interventions. Conversely, the SBS technique, if placed across the papilla, is technically simple at initial placement and re-intervention at stent occlusion. However, SBS has potential disadvantages of overexpansion of the CBD because of parallel placement of multiple SEMS, which can lead to portal vein thrombosis. Given the limited evidence available, a well-designed randomized controlled trial comparing these two techniques is warranted. PMID:26136361

  13. Effects of diffusion coefficients and struts apposition using numerical simulations for drug eluting coronary stents.

    Science.gov (United States)

    Mongrain, Rosaire; Faik, Isam; Leask, Richard L; Rodés-Cabau, Josep; Larose, Eric; Bertrand, Olivier F

    2007-10-01

    In the context of drug eluting stent, we present two-dimensional numerical models of mass transport of the drug in the wall and in the lumen to study the effect of the drug diffusion coefficients in the three principal media (blood, vascular wall, and polymer coating treated as a three-compartment problem) and the impact of different strut apposition configurations (fully embedded, half embedded, and not embedded). The different conditions were analyzed in terms of their consequence on the drug concentration distribution in the arterial wall. We apply the concept of the therapeutic window to the targeted vascular wall region and derive simple metrics to assess the efficiency of the various stent configurations. Although most of the drug is dispersed in the lumen, variations in the blood flow rate within the physiological range of coronary blood flow and the diffusivity of the drug molecule in the blood were shown to have a negligible effect on the amount of drug in the wall. Our results reveal that the amount of drug cumulated in the wall depends essentially on the relative values of the diffusion coefficients in the polymer coating and in the wall. Concerning the strut apposition, it is shown that the fully embedded strut configuration would provide a better concentration distribution.

  14. Experiment Study of The Preventive Effects of Valsartan Eluting Stent on In- stent Restenosis

    Institute of Scientific and Technical Information of China (English)

    陈津; 陈纪言; 周颖玲; 李光; 罗建方; 余丹青; 张励庭; 黄文晖

    2003-01-01

    Objectives Background -Neointima hyperplasia and arterial re modeling are themain mechanisms of restenosis after percutaneoustransluminal coronary angioplasty. The successful useof coronary stents neutralizes the ac ute elastic recoiland improves the remodeling mode with reducingrestenosis rate by 10 % . But the in - stent neointimahyperplasia becomes more severe. This study aims toset up model of in - stent restenosis in vivo, and to e-valuate the preventive role of implantation of valsartaneluting stent for restenosis. Methods and ResultsTwenty -two male New Zealand white rabbits were di-vided into control group and valsartan group. In-travascular ultrasonic (IVUS) results showed the in-trastent neointimal areas of the control group werelarger than those of the valsartan group ( P < 0.01 ) .The minimal lumen area of control group was smallerthan that of the valsartan group ( P < 0.01). Angiog-raphy results showed the normal lumen diameters weresimilar between two groups ( P> 0.05) . The lumenstenosis rates compared with the normal diameters ofthe valsartan group were significantly improved overthat of the control group ( P < 0. 05) . It was compa-rable to the IVUS analysis. There were no cases of a-neurysm or thrombosis. Conclusions Valsartan e-luting stents produced a significant inhibition ofneointimal hyperplasia and luminal encroachment inrabbits without obviously producing any serious side -effects. These results demonstrate the potential thera-peutic benefit of valsartan eluting stents in the pre-vention and treatment of human coronary restenosis.

  15. Infrarenal abdominal aortic aneurysm. Endovascular repair with stent grafts; Infrarenales Bauchaortenaneurysma. Endovaskulaere Stent-Graft-Therapie

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, M.; Voshage, G.; Landwehr, P. [Klinik fuer Diagnostische und Interventionelle Radiologie, Gefaesszentrum Hannover, Diakoniekrankenhaus Henriettenstiftung gGmbH, Hannover (Germany); Busch, T. [Klinik fuer Gefaesschirurgie, Gefaesszentrum Hannover, Diakoniekrankenhaus Henriettenstiftung gGmbH, Hannover (Germany)

    2008-09-15

    As an alternative to surgery, endovascular therapy with stent grafts has become the second main treatment option for infrarenal abdominal aortic aneurysms. Unlike surgery, endovascular treatment with stent grafts is also applicable in patients unfit for open repair. Despite current improvements in endovascular repair devices, significant anatomic barriers still exclude this technique for a large number of patients. Computed tomography, magnetic resonance imaging, and ultrasound are essential for diagnostics, preintervention planning, and postintervention follow-up of abdominal aneurysms treated with stent grafts. This review covers etiology, pathology, and diagnostic aspects. Materials and methods for endovascular treatment of abdominal aortic aneurysms are presented in detail, and clinical results and complications are discussed. (orig.) [German] Die endovaskulaere Therapie des infrarenalen Bauchaortenaneurysmas hat sich als Alternative zur offenen chirurgischen Versorgung etabliert. Im Gegensatz zu Letzterer ist die Aneurysmatherapie mittels Stent-Grafts auch bei schwerkranken, nicht operationsfaehigen Patienten moeglich, wobei der Nutzen kontrovers diskutiert wird. Im Gegensatz zur klassischen transabdominellen Operation ist die Stent-Graft-Technik anatomischen Einschraenkungen unterworfen, die aber kuenftig aufgrund bereits abzusehender technischer Weiterentwicklungen eine geringere Rolle spielen werden. Die Diagnostik, die Entscheidung fuer eine endovaskulaere Therapie, die praeinterventionelle Planung und die Nachsorge erfordern den Einsatz bildgebender Verfahren, v. a. der Computer- und Magnetresonanztomographie sowie der Sonographie. Die fuer die endovaskulaere Aneurysmabehandlung relevanten Aspekte der Diagnostik werden dargestellt. Auf die Technik, die Materialien, die Ergebnisse und die Komplikationen der Stent-Graft-Behandlung wird ausfuehrlich eingegangen. (orig.)

  16. Creation of individual ideally shaped stents using multi-slice CT: in vitro results from the semi-automatic virtual stent (SAVS) designer.

    Science.gov (United States)

    Hyodoh, Hideki; Katagiri, Yoshimi; Sakai, Toyohiko; Hyodoh, Kazusa; Akiba, Hidenari; Hareyama, Masato

    2005-08-01

    To plan stent-grafting for thoracic aortic aneurysm with complicated morphology, we created a virtual stent-grafting program [Semi Automatic Virtual Stent (SAVS) designer] using three-dimensional CT data. The usefulness of the SAVS designer was evaluated by measurement of transformed anatomical and straight stents. Curved model images (source, multi-planer reconstruction and volume rendering) were created, and a hollow virtual stent was produced by the SAVS designer. A straight Nitinol stent was transformed to match the curved configuration of the virtual stent. The accuracy of the anatomical stent was evaluated by experimental strain phantom studies in comparison with the straight stent. Mean separation length was 0 mm in the anatomical stent [22 mm outer diameter (OD)] and 5 mm in the straight stent (22 mm OD). The straight stent strain voltage was four times that of the anatomical stent at the stent end. The anatomical stent is useful because it fits the curved structure of the aorta and reduces the strain force compared to the straight stent. The SAVS designer can help to design and produce the anatomical stent.

  17. Local hemodynamic changes caused by main branch stent implantation and subsequent virtual side branch balloon angioplasty in a representative coronary bifurcation.

    Science.gov (United States)

    Williams, Andrew R; Koo, Bon-Kwon; Gundert, Timothy J; Fitzgerald, Peter J; LaDisa, John F

    2010-08-01

    Abnormal blood flow patterns promoting inflammation, cellular proliferation, and thrombosis may be established by local changes in vessel geometry after stent implantation in bifurcation lesions. Our objective was to quantify altered hemodynamics due to main vessel (MV) stenting and subsequent virtual side branch (SB) angioplasty in a coronary bifurcation by using computational fluid dynamics (CFD) analysis. CFD models were generated from representative vascular dimensions and intravascular ultrasound images. Time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and fractional flow reserve (FFR) were quantified. None of the luminal surface was exposed to low TAWSS (stenting introduced eccentric areas of low TAWSS along the lateral wall of the MV. Virtual SB angioplasty resulted in a more concentric region of low TAWSS in the MV distal to the carina and along the lateral wall of the SB. The luminal surface exposed to low TAWSS was similar before and after virtual SB angioplasty (rest: 43% vs. 41%; hyperemia: 18% vs. 21%) and primarily due to stent-induced flow alterations. Sites of elevated OSI (>0.1) were minimal but more impacted by general vessel geometry established after MV stenting. FFR measured at a jailed SB was within the normal range despite angiographic stenosis of 54%. These findings indicate that the most commonly used percutaneous interventional strategy for a bifurcation lesion causes abnormal local hemodynamic conditions. These results may partially explain the high clinical event rates in bifurcation lesions.

  18. Risk Factors and Clinical Evaluation of Superficial Femoral Artery Stent Fracture: Prote'ge'GPS Stent

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Da Un; Kim, Jae Kyu; Jung, Hye Doo; Huh, Tae Wook; Yim, Nam Yeol; Oh, Hyun jun; Choi, Soo Jin Na [Chonnam National University Hospital, Chonnam National University, Medical School, Gwangju (Korea, Republic of); Chang, Nam Kyu [Chonnam National University Hwasun Hospital, Chonnam National University, Medical School, Hwasun (Korea, Republic of)

    2010-12-15

    To evaluate the occurrence of superficial femoral artery stent fractures, the risk factors of stent fracture, and the relationship between fractures and clinical findings. Of the 38 patients who underwent treatment with Prote'ge'GPS stenting due to arterial occlusions on the superficial femoral artery, 17 also underwent a clinical analysis. Forty-three stents were inserted in the 17 superficial femoral arteries, ranging between 15 and 50 cm in length, with a mean treated length of 26.4 cm (15-50 cm). A fracture was evaluated by taking a PA and lateral simple radiography, as well as a follow-up evaluation accompanied with a CT angiography, DSA, and a color Doppler sonography. The examination involved the assessment of the difference between bone fractures due to length, placement, and frequency. Fractures occurred in 13 of 43 stents (30.2%). A total of 10 (71.4%) occurred in the upper third, compared to 4 (28.6%) in the lower third of the superficial femoral artery. In addition, 10 stents (71.4%) had a single strut fracture, whereas 4 (28.6%) had multiple strut fractures. A stent fracture occurred more frequently when the stents and lesions were longer (p=0.021, 0.012) and the stents were inserted near the joint. However, there was no significant relationship between stent numbers and the fractures (p=0.126). When the stents were inserted along the popliteal artery, a stent fracture occurred more frequently in the lower third of the artery. The stent fractures did not significantly influence the patency rate of the stented artery (p=0.44) Prote'ge'GPS stents in the superficial femoral artery revealed a considerable number of fractures and the fracture frequency showed a significant relationship with the length of stents and lesions. The closer stent insertion was to the joints, the more frequently fractures occurred. There were no evident significant relationships between the presence of stent fractures and the patency of the stented arteries

  19. Investigating surface topology and cyclic-RGD peptide functionalization on vascular endothelialization.

    Science.gov (United States)

    McNichols, Colton; Wilkins, Justin; Kubota, Atsutoshi; Shiu, Yan T; Aouadi, Samir M; Kohli, Punit

    2014-02-01

    The advantages of endothelialization of a stent surface in comparison with the bare metal and drug-eluting stents used today include reduced late-stent restenosis and in-stent thrombosis. In this article, we study the effect of surface topology and functionalization of tantalum (Ta) with cyclic-(arginine-glycine-aspartic acid-d-phenylalanine-lysine) (cRGDfK) on the attachment, spreading, and growth of vascular endothelial cells. Self-assembled nanodimpling on Ta surfaces was performed using a one-step electropolishing technique. Next, cRGDfK was covalently bonded onto the surface using silane chemistry. Our results suggest that nanotexturing alone was sufficient to enhance cell spreading, but the combination of a nanodimpled surfaces along with the cRGDfK peptide may produce a better endothelialization coating on the surface in terms of higher cell density, better cell spreading, and more cell-cell interactions, when compared to using cRGDfK peptide functionalization alone or nanotexturing alone. We believe that future research should look into how to implement both modifications (topographic and chemical modifications) to optimize the stent surface for endothelialization. PMID:23505215

  20. Circadian Variation in Coronary Stent Thrombosis

    NARCIS (Netherlands)

    Mahmoud, Karim D.; Lennon, Ryan J.; Ting, Henry H.; Rihal, Charanjit S.; Holmes, David R.

    2011-01-01

    Objectives We sought to determine the circadian, weekly, and seasonal variation of coronary stent thrombosis. Background Other adverse cardiovascular events such as acute myocardial infarction are known to have higher incidences during the early morning hours, Mondays, and winter months. Methods The

  1. Oesphageal Stenting for palliation of malignant mesothelioma

    Directory of Open Access Journals (Sweden)

    Rahamim Joseph

    2008-01-01

    Full Text Available Abstract Dyspahgia in patients with malignant mesothelioma is usually due to direct infiltration of the eosophagus by the tumour. It can be distressing for the patient and challenging for the physician to treat. We describe three cases in which this condition has been successfully palliated with self expanding esophageal stents.

  2. Carotid artery stenting : a 2009 update

    NARCIS (Netherlands)

    Zeebregts, Clark J.; Meerwaldt, Robbert; Geelkerken, Robert H.

    2009-01-01

    Purpose of review Carotid endarterectomy (CEA) is is still considered the gold standard in the treatment of patients with significant carotid stenosis and has proven its value over the past decades. Endovascular techniques have evolved, and carotid artery stenting (CAS) is challenging CEA to become

  3. Hyperperfusion syndrome after carotid stent angioplasty

    Energy Technology Data Exchange (ETDEWEB)

    Grunwald, I.Q.; Politi, M.; Reith, W.; Krick, C.; Karp, K.; Zimmer, A.; Struffert, T.; Kuehn, A.L.; Papanagiotou, P. [University of the Saarland, Department for Interventional and Diagnostic Neuroradiology, Homburg (Germany); Roth, C.; Haass, A. [University of the Saarland, Clinic for Neurology, Homburg (Germany)

    2009-03-15

    This study assesses the incidence and causes of hyperperfusion syndrome occurring after carotid artery stenting (CAS). We retrospectively reviewed the clinical database of 417 consecutive patients who were treated with CAS in our department to identify patients who developed hyperperfusion syndrome and/or intracranial hemorrhage. Magnetic resonance imaging (MRI) including fluid-attenuated inversion recovery and diffusion-weighted imaging was performed before and after CAS in 269 cases. A Spearman's rho nonparametric correlation was performed to determine whether there was a correlation between the occurrence/development of hyperperfusion syndrome and the patient's age, degree of stenosis on the stented and contralateral side, risk factors such as diabetes, smoking, hypertension, adiposity, gender and fluoroscopy time, and mean area of postprocedural lesions as well as preexisting lesions. Significance was established at p < 0.05. Of the 417 carotid arteries stented and where MRI was also completed, we found hyperperfusion syndrome in 2.4% (ten cases). Patients who had preexisting brain lesions (previous or acute stroke) were at a higher risk of developing hyperperfusion syndrome (p = 0.022; Spearman's rho test). We could not validate any correlation with the other patient characteristics. Extensive microvascular disease may be a predictor of hyperperfusion syndrome after carotid stent placement. We believe that further studies are warranted to predict more accurately which patients are at greater risk of developing this often fatal complication. (orig.)

  4. Restenosis begets restenosis : implications for stent selection

    NARCIS (Netherlands)

    Wijpkema, J. S.; Anthonio, R. L.; Jessurun, G. A. J.; Dijk, W. A.; Tio, R. A.; Zijlstra, F.

    2008-01-01

    Background: Identifying the risk for restenosis is of critical importance in the stent selection process of patients undergoing percutaneous coronary intervention (PCI). Therefore, we sought to determine if a history of clinical recurrence (CR) after PCI increases the risk of CR after treatment of a

  5. Asymmetric Gepner Models (Revisited)

    CERN Document Server

    Gato-Rivera, B

    2010-01-01

    We reconsider a class of heterotic string theories studied in 1989, based on tensor products of N=2 minimal models with asymmetric simple current invariants. We extend this analysis from (2,2) and (1,2) spectra to (0,2) spectra with SO(10) broken to the Standard Model. In the latter case the spectrum must contain fractionally charged particles. We find that in nearly all cases at least some of them are massless. However, we identify a large subclass where the fractional charges are at worst half-integer, and often vector-like. The number of families is very often reduced in comparison to the 1989 results, but there are no new tensor combinations yielding three families. All tensor combinations turn out to fall into two classes: those where the number of families is always divisible by three, and those where it is never divisible by three. We find an empirical rule to determine the class, which appears to extend beyond minimal N=2 tensor products. We observe that distributions of physical quantities such as th...

  6. A retrievable nitinol endobronchial stent : an experimental study in dog

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Sang Jin; Park, Sang Soo; Yoon, Hyun Ki; Sung, Kyu Bo; Song, Ho Young [Asan Medical Center, Ulsan Univ. College of Medicine, Seoul (Korea, Republic of); Kang, Sung Gwon [Inha Univ. College of Medicine, Inchon (Korea, Republic of)

    1999-06-01

    The purpose of this study was to evaluate the safety and the retrievability of a new covered retrievable nitinol tracheobronchial stent. Stents were knitted from 0.2mm nitinol wire, covered with polyurethane, and were 20-22mm in diameter and 2cm in length. Under fluoroscopic guidance, a stent was placed in the normal right bronchus intermedius of ten dogs. Using a retrieval hook, stent retrieval was attempted after 1 month(N=5) or 2 months(N=5). After removal, the dogs were sacrificed and their their tracheobronchial trees were examined grossly and histologically. Eleven stents were successfully placed in ten dogs. Migration and expectoration occurred in four of ten stents in nine dogs(40%). Five stents were successfully removed from six dogs(83%). Without significant difference between the two groups, mild to moderate mucosal hyperplasia was noted at the sites of stents as well as above and below them. On microscopy, three of five dogs showed pneumonia in the right middle lobes, but none of the stents was covered with epithelium. Temporary placement of a covered expandable nitinol stent in the tracheobronchial tree is feasible, but to establish its efficacy, further experimental studies are needed.

  7. Clinical, angiographic and procedural characteristics of longitudinal stent deformation.

    Science.gov (United States)

    Guler, A; Guler, Y; Acar, E; Aung, S M; Efe, S C; Kilicgedik, A; Karabay, C Y; Barutcu, S; Tigen, M K; Pala, S; İzgi, A; Esen, A M; Kirma, C

    2016-08-01

    Recently, longitudinal stent deformation (LSD) has been reported increasingly. Even though the reported cases included almost all stent designs, most cases were seen in the Element™ stent design (Boston Scientific, Natick, MA, USA). It is considered that stent design, lesion and procedural characteristics play a role in the etiology of LSD. Yet, the effect of LSD on long-term clinical outcomes has not been studied well. Element stents implanted between January 2013 and April 2015 in our hospital were examined retrospectively. Patients were grouped into two according to the presence of LSD, and their clinical, lesion and procedural characteristics were studied. Twenty-four LSD's were detected in 1812 Element stents deployed in 1314 patients (1.83 % of PCI cases and 1.32 % of all Element stents). LMCA lesions (16.7 % vs 1.6 %, p LSD than in cases without it. In addition, the number of stents, stent inflation pressure and the use of post-dilatation were significantly different between the two groups. Two patients had an adverse event during the follow-up period. LSD is a rarely encountered complication, and is more common in complex lesions such as ostial, bifurcation and LMCA lesions. The use of extra-support guiding catheter, extra-support guidewires and low stent inflation pressure increases the occurrence of LSD. Nevertheless, with increased awareness of LSD and proper treatment, unwanted long-term outcomes can be successfully prevented. PMID:27198891

  8. Thin film nitinol covered stents: design and animal testing.

    Science.gov (United States)

    Levi, Daniel S; Williams, Ryan J; Liu, Jasen; Danon, Saar; Stepan, Lenka L; Panduranga, Mohanchandra K; Fishbein, Michael C; Carman, Greg P

    2008-01-01

    Interventionalists in many specialties have the need for improved, low profile covered stents. Thin films of nitinol (<5-10 microns) could be used to improve current covered stent technology. A "hot target" sputter deposition technique was used to create thin films of nitinol for this study. Covered stents were created from commercially available balloon-inflatable and self-expanding stents. Stents were deployed in a laboratory flow loop and in four swine. Uncovered stent portions served as controls. Postmortem examinations were performed 2-6 weeks after implantation. In short-term testing, thin film nitinol covered stents deployed in the arterial circulation showed no intimal proliferation and were easily removed from the arterial wall postmortem. Scanning electron microscopy showed a thin layer of endothelial cells on the thin film, which covered the entire film by 3 weeks. By contrast, significant neointimal hyperplasia occurred on the luminal side of stents deployed in the venous circulation. Extremely low-profile covered stents can be manufactured using thin films of nitinol. Although long-term studies are needed, thin film nitinol may allow for the development of low-profile, nonthrombogenic covered stents. PMID:18496269

  9. New approach to quantitative angiographic assessment after stent implantation.

    Science.gov (United States)

    Reimers, B; Di Mario, C; Di Francesco, L; Moussa, I; Blengino, S; Martini, G; Reiber, J H; Colombo, A

    1997-04-01

    The new generation quantitative angiographic systems apply the interpolated technique to calculate the reference diameter at the site of the stenosis by integrating measurements of the segments proximal and distal to the stenosis. After stent implantation these measurements can be misleading as the treated segment, which is frequently larger than the adjacent not stented segments, is included in the measurements. The consequence is an overestimation of the reference diameter and the residual diameter stenosis. The present study was performed to compare this conventional technique of measurement with a new method which excludes the stented segment for the calculation of the reference diameter. Fifty-two lesions treated with poorly radiopaque stents (56% Palmaz-Schatz, 28% NIR, 10% Gianturco-Roubin, 6% Wallstent) expanded at high pressure (> = or 16 atm) were analyzed according to the conventional and stent excluded method. After stent implantation the reference diameter was 3.39 +/- 0.48 mm with conventional measurements and 3.02 +/- 0.45 mm with the stent excluded method (P < 0.05). The corresponding % diameter stenosis was 13 +/- 9 for the conventional technique and 1 +/- 13 for the stent excluded analysis (P < 0.05). The new approach to quantitative coronary analysis after stenting provides higher accuracy in reference diameter calculations and allows a more appropriate matching of stented segments with adjacent normal segments.

  10. Surgical stent for dental implant using cone beam CT images

    International Nuclear Information System (INIS)

    The purpose of this study is to develop a surgical stent for dental implant procedure that can be easily applied and affordable by using cone beam computerized tomography (CBCT). Aluminum, Teflon-PFA (perfluoroalkoxy), and acetal (polyoxymethylene plastic) were selected as materials for the surgical stent. Among these three materials, the appropriate material was chosen using the CBCT images. The surgical stent, which could be easily placed into an oral cavity, was designed with chosen material. CBCT images of the new surgical stent on mandible were obtained using Alphard-3030 dental CT system (Asahi Roentgen Co., Ltd., Kyoto, Japan). The point of insertion was prescribed on the surgical stent with the multiplanar reconstruction software of OnDemand3D (CyberMed Inc., Seoul, Korea). Guide holes were made at the point of insertion on the surgical stent using newly designed guide jig. CBCT scans was taken for the second time to verify the accuracy of the newly designed surgical stent. Teflon-PFA showed radiologically excellent image characteristics for the surgical stent. High accuracy and reproducibility of implantation were confirmed with the surgical stent. The newly designed surgical stent can lead to the accurate implantation and achieve the clinically predictable result.

  11. Self-made Palmaz stent: an experimental swine model study

    International Nuclear Information System (INIS)

    Objective: To investigate the histologic changes and physicochemical stability of self-made Palmaz stent placed in swine arteries. Methods: The self-made Palmaz stent was made of 316L stainless steel wire. Nine stents were respectively placed within internal carotid, renal and iliac arteries of six pigs. Pigs were euthanized at intervals of 0.5, 1 and 3 months respectively and angiography were performed. Immediately followed by light and electro scanning microscopy for the stent zones. Results: All stents were successfully implanted in the target arteries and were patent shown in the angiographic examination immediately after the stent placement. Eight stents (8/9) remained patent at the time before euthanasia. No migration of stent were shown in the follow-up angiography. Light and electron scanning microscopy showed that the surface of the stents was covered by a thin layer of endothelial cells 2 weeks after the procedure and completely covered after 4 weeks. No inflammation occurred. Conclusions: The self-made Palmaz stent has good physicochemical stability and histocompatibility with easy placement, rather long term patency, histopathologic stability and thus the promising for clinical application

  12. Forgotten ureteric stents in renal transplant recipients: Three case reports

    Directory of Open Access Journals (Sweden)

    Mallikarjun Bardapure

    2014-01-01

    Full Text Available Ureteric stents are widely used in renal transplantation to minimize the early urological complications. Ureteric stents are removed between two and 12 weeks following trans-plantation, once the vesico-ureteric anastomosis is healed. Ureteric stents are associated with considerable morbidity due to complications such as infection, hematuria, encrustations and migration. Despite the patient having a regular follow-up in the renal transplant clinic, ureteric stents may be overlooked and forgotten. The retained or forgotten ureteric stents may adversely affect renal allograft function and could be potentially life-threatening in immunocompromised transplant recipients with a single transplant kidney. Retrieving these retained ureteric stents could be challenging and may necessitate multimodal urological treatments. We report three cases of forgotten stents in renal transplant recipients for more than four years. These cases emphasize the importance of patient education about the indwelling ureteric stent and possibly providing with a stent card to the patient. Maintaining a stent register, with a possible computer tracking system, is highly recommended to prevent such complications.

  13. Experimental and computational studies on the flow fields in aortic aneurysms associated with deployment of AAA stent-grafts

    Institute of Scientific and Technical Information of China (English)

    Xiwen Zhang; Zhaohui Yao; Yan Zhang; Shangdong Xu

    2007-01-01

    Pulsatile flow fields in rigid abdominal aortic aneurysm (AAA) models were investigated numerically, and the simulation results are found in good agreement with particle image velocimetry (PIV) measurements. There are one or more vortexes in the AAA bulge, and a fairly high wall shear stress exists at the distal end, and thus the AAA is in danger of rupture. Medical treatment consists of inserting a vascular stent-graft in the AAA, which would decrease the blood impact to the inner walls and reduce wall shear stress so that the rupture could be prevented. A new computational model, based on porous medium model, was developed and results are documented. The rapeutic effect of the stent-graft was verified numerically with the new model.

  14. Should intentional endovascular stent-graft coverage of the left subclavian artery be preceded by prophylactic revascularisation?

    DEFF Research Database (Denmark)

    Weigang, Ernst; Parker, Jack A T C; Czerny, Martin;

    2011-01-01

    Thoracic endovascular aortic repair (TEVAR) has emerged as a promising therapeutic alternative to conventional open aortic replacement but it requires suitable proximal and distal landing zones for stent-graft anchoring. Many aortic pathologies affect in the immediate proximity of the left...... subclavian artery (LSA) limiting the proximal landing zone site without proximal vessel coverage. In patients in whom the distance between the LSA and aortic lesion is too short, extension of the landing zone can be obtained by covering the LSA's origin with the endovascular stent graft (ESG). This manoeuvre...... has the potential for immediate and delayed neurological and vascular symptoms. Some authors, therefore, propose prophylactic revascularisation of the LSA by transposition or bypass, while others suggest prophylactic revascularisation only under certain conditions, and still others see no requirement...

  15. Ureteral stent retrieval using the crochet hook technique in females.

    Directory of Open Access Journals (Sweden)

    Takashi Kawahara

    Full Text Available INTRODUCTION: We developed a method for ureteral stent removal in female patients that requires no cystoscopy or fluoroscopic guidance using a crochet hook. In addition, we also investigated the success rate, complications and pain associated with this procedure. METHODS: A total of 40 female patients (56 stents underwent the removal of ureteral stents. All procedures were carried out with the patients either under anesthesia, conscious sedation, or analgesic suppositories as deemed appropriate for each procedure including Shock Wave Lithotripsy (SWL, Ureteroscopy (URS, Percutaneous Nephrolithotomy (PCNL, and ureteral stent removal. At the time of these procedures, fluoroscopy and/or cystoscopy were prepared, but they were not used unless we failed to successfully remove the ureteral stent using the crochet hook. In addition, matched controls (comprising 50 stents which were removed by standard ureteral stent removal using cystoscopy were used for comparison purposes. RESULTS: A total of 47 of the 56 stents (83.9% were successfully removed. In addition, 47 of 52 (90.4% were successfully removed except for two migrated stents and two heavily encrusted stents which could not be removed using cystoscopy. Ureteral stent removal using the crochet hook technique was unsuccessful in nine patients, including two encrustations and two migrations. Concerning pain, ureteral stent removal using the crochet hook technique showed a lower visual analogue pain scale (VAPS score than for the standard technique using cystoscopy. CONCLUSIONS: Ureteral stent removal using a crochet hook is considered to be easy, safe, and cost effective. This technique is also easy to learn and is therefore considered to be suitable for use on an outpatient basis.

  16. Magnetically Modified Asymmetric Supercapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This Small Business Innovation Research Phase I project is for the development of an asymmetric supercapacitor that will have improved energy density and cycle...

  17. Early complications of stenting in patients with congenital heart disease : a multicentre study

    NARCIS (Netherlands)

    van Gameren, Menno; Witsenburg, Maarten; Takkenberg, Johanna J. M.; Boshoff, Derize; Mertens, Luc; van Oort, Anton M.; de Wolf, DanieL; Freund, Matthias; Sreeram, Narayanswani; Bokenkamp, Regina; Talsma, Melle D.; Gewillig, Marc

    2006-01-01

    Aims Stenting has become an established interventional cardiology procedure for congenital heart disease. Although most stent procedures are completed successfully, complications may occur. This multicentre study evaluated early complications after stenting in patients with congenital heart disease,

  18. Safety and efficacy of using the Viabahn endoprosthesis for percutaneous treatment of vascular access complications after transfemoral aortic valve implantation

    DEFF Research Database (Denmark)

    De Backer, Ole; Arnous, Samer; Sandholt, Benjamin;

    2015-01-01

    Vascular access complications (VACs) remain one of the biggest challenges when performing transcatheter aortic valve implantation (TAVI). This study aimed to investigate the short- and medium-term safety and efficacy of the Viabahn endoprosthesis (Gore, Flagstaff, AZ) when used to treat TAVI......-induced vascular injury. Over a 40-month period, 354 patients underwent true percutaneous transfemoral (TF)-TAVI using a CoreValve and Prostar-XL closure system; this was our study population. A VAC leading to acute intervention occurred in 72 patients (20.3%) - of these, 18 were managed by balloon angioplasty, 48...... stenting versus patients without vascular complications. Two patients (4.5%) presented with new-onset claudication; one of them had the stent implanted covering the deep femoral artery (DFA). At medium-term follow-up (median 372 days; range 55 to 978 days) duplex ultrasound showed 100% patency...

  19. Collagen vascular disease

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001223.htm Collagen vascular disease To use the sharing features on this page, ... were previously said to have "connective tissue" or "collagen vascular" disease. We now have names for many of many ...

  20. Multicatalyst system in asymmetric catalysis

    CERN Document Server

    Zhou, Jian

    2014-01-01

    This book introduces multi-catalyst systems by describing their mechanism and advantages in asymmetric catalysis.  Helps organic chemists perform more efficient catalysis with step-by-step methods  Overviews new concepts and progress for greener and economic catalytic reactions  Covers topics of interest in asymmetric catalysis including bifunctional catalysis, cooperative catalysis, multimetallic catalysis, and novel tandem reactions   Has applications for pharmaceuticals, agrochemicals, materials, and flavour and fragrance

  1. On Asymmetric Quantum MDS Codes

    CERN Document Server

    Ezerman, Martianus Frederic; Ling, San

    2010-01-01

    Assuming the validity of the MDS Conjecture, the weight distribution of all MDS codes is known. Using a recently-established characterization of asymmetric quantum error-correcting codes, linear MDS codes can be used to construct asymmetric quantum MDS codes with $d_{z} \\geq d_{x}\\geq 2$ for all possible values of length $n$ for which linear MDS codes over $\\F_{q}$ are known to exist.

  2. Mobile Termination with Asymmetric Networks

    OpenAIRE

    Dewenter, Ralf; Haucap, Justus

    2003-01-01

    This paper examines mobile termination fees and their regulation when networks are asymmetric in size. It is demonstrated that with consumer ignorance about the exact termination rates (a) a mobile network?s termination rate is the higher the smaller the network?s size (as measured through its subscriber base) and (b) asymmetric regulation of only the larger operators in a market will, ce-teris paribus, induce the smaller operators to increase their termination rates. The results are supporte...

  3. Retreatment of recanalized aneurysms after Y-stent-assisted coil embolization with double enterprise stents: case report and systematic review of the literature.

    Science.gov (United States)

    Kono, Kenichi; Shintani, Aki; Terada, Tomoaki

    2014-01-01

    It is necessary to consider possibility of recanalization and retreatment after coil embolization for cerebral aneurysms. There is concern that retreatment for recanalized aneurysms after Y-stent-assisted coil embolization may be difficult because of double stents, especially in Y-stents with double closed-cell stents owing to narrowed structures. However, no detailed reports of retreatment after Y-stent have been reported. Between July 2010 and June 2013, we treated four aneurysms with Y-stent-assisted coil embolization using Enterprise closed-cell stents. Recanalization occurred in one case (25%), and retreatment was performed. We easily navigated a microcatheter into the target portions of the aneurysm through the Y-stent and occluded the aneurysm with coils. Additionally, by systematically searching in PubMed, we found 105 cases of Y-stent-assisted coil embolization using Enterprise stents or Neuroform stents with more than 6 months of follow-up. Among them, retreatment was performed in 10 cases (9.5%). There were no significant differences in retreatment rates among different stent combinations (P=0.91; Fisher's exact test). In conclusion, navigation of a microcatheter into the aneurysm through the Y-stent with double Enterprise stents was feasible, and retreatment rates after Y-stent-assisted coiling may not depend on stent combinations.

  4. Biolimus-eluting biodegradable polymer-coated stent versus durable polymer-coated sirolimus-eluting stent in unselected patients receiving percutaneous coronary intervention (SORT OUT V)

    DEFF Research Database (Denmark)

    Christiansen, Evald Høj; Jensen, Lisette Okkels; Thayssen, Per;

    2013-01-01

    Third-generation biodegradable polymer drug-eluting stents might reduce the risk of stent thrombosis compared with first-generation permanent polymer drug-eluting stents. We aimed to further investigate the effects of a biodegradable polymer biolimus-eluting stent compared with a durable polymer-...

  5. Iliac artery occlusion with "oxbow lake" formation following stent deployment in a tortuous external iliac artery during EVAR: a case report.

    Science.gov (United States)

    Culverwell, Adam D; Kent, Patrick; Puppala, Sapna

    2011-10-01

    In this case report, we describe a complication that we term the "oxbow lake" deformity. This phenomenon occurs when a tortuous elongated external iliac artery segment is artificially straightened by an iliac stent resulting in kinking and compression of a redundant loop with lumen compromise. We describe the anatomy, corrective treatment, and outcome. This occurrence is potentially foreseeable with tortuous vascular anatomy and recognition can allow appropriate management planning avoiding complications for the patient. PMID:21788283

  6. Vascular grading of angiogenesis

    DEFF Research Database (Denmark)

    Hansen, S; Grabau, D A; Sørensen, Flemming Brandt;

    2000-01-01

    was moderately reproduced (kappa = 0.59). Vascular grade was significantly associated with axillary node involvement, tumour size, malignancy grade, oestrogen receptor status and histological type. In univariate analyses vascular grade significantly predicted recurrence free survival and overall survival for all...... patients (P analysis showed that vascular grading contributed with independent prognostic value in all patients (P

  7. Asymmetric Gepner models (revisited)

    Energy Technology Data Exchange (ETDEWEB)

    Gato-Rivera, B. [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands)] [Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain); Schellekens, A.N., E-mail: t58@nikhef.n [NIKHEF Theory Group, Kruislaan 409, 1098 SJ Amsterdam (Netherlands)] [Instituto de Fisica Fundamental, CSIC, Serrano 123, Madrid 28006 (Spain)] [IMAPP, Radboud Universiteit, Nijmegen (Netherlands)

    2010-12-11

    We reconsider a class of heterotic string theories studied in 1989, based on tensor products of N=2 minimal models with asymmetric simple current invariants. We extend this analysis from (2,2) and (1,2) spectra to (0,2) spectra with SO(10) broken to the Standard Model. In the latter case the spectrum must contain fractionally charged particles. We find that in nearly all cases at least some of them are massless. However, we identify a large subclass where the fractional charges are at worst half-integer, and often vector-like. The number of families is very often reduced in comparison to the 1989 results, but there are no new tensor combinations yielding three families. All tensor combinations turn out to fall into two classes: those where the number of families is always divisible by three, and those where it is never divisible by three. We find an empirical rule to determine the class, which appears to extend beyond minimal N=2 tensor products. We observe that distributions of physical quantities such as the number of families, singlets and mirrors have an interesting tendency towards smaller values as the gauge groups approaches the Standard Model. We compare our results with an analogous class of free fermionic models. This displays similar features, but with less resolution. Finally we present a complete scan of the three family models based on the triply-exceptional combination (1,16{sup *},16{sup *},16{sup *}) identified originally by Gepner. We find 1220 distinct three family spectra in this case, forming 610 mirror pairs. About half of them have the gauge group SU(3)xSU(2){sub L}xSU(2){sub R}xU(1){sup 5}, the theoretical minimum, and many others are trinification models.

  8. Implante de stent dentro de stent recém-implantado em ponte de veia safena para otimização do resultado angiográfico Stenting a stent in saphenous vein graft to optimize the angiographic result

    Directory of Open Access Journals (Sweden)

    Antonio Esteves Fº

    1998-03-01

    Full Text Available Mulher de 60 anos, com angina progressiva e revascularização do miocárdio, há oito anos, com ponte de veia safena para coronária direita e anastomose de artéria mamaria esquerda para artéria descendente anterior. Submetida a implante de stent Gianturco-Roubin II em terço proximal da ponte de veia safena para artéria coronária direita, com resultado insatisfatório pela persistência de lesão residual, provavelmente, decorrente de prolapso para dentro da luz de material aterosclerótico através dos coils. Foi implantado outro stent (Palmaz-Schatz biliar dentro do stent GRII com sucesso e ótimo resultado angiográfico. Um 2º stent Palmaz-Schatz biliar foi implantado em lesão distal no corpo da ponte, ultrapassando os dois stents, anteriormente implantados, com sucesso. Em algumas situações, implante de stent dentro de outro stent é recurso útil para otimização de resultado angiográfico do implante de um stent.A 60 year-old woman with progressive angina who had been submitted to saphenous bypass-graft to right coronary artery and a left mammary artery graft to anterior descending artery eight years previously, underwent implantation of a Gianturco Roubin II stent in the proximal third of the saphenous vein graft. The result was suboptimal by persistence of a residual stenosis probably due to prolapse of atherosclerotic material through the coil spaces. Another stent (Palmaz-Schatz biliar stent was implanted at the previously stented site with no residual stenosis. Another Palmaz-Schatz biliar stent was successfully implanted in the distal body of the graft to treat another lesion (passing through the previously stents without difficulty. Stenting a stent, in selected situations, is a useful tool to optimize the angiographic result of stent implantation.

  9. Bioresorbable vascular scaffolds—what does the future bring?

    Science.gov (United States)

    Gil, Robert J.

    2016-01-01

    Bioresorbable vascular scaffolds (BVS) have emerged as an interesting alternative since the presence of the prosthesis in the coronary artery is transient. This technology enables to restore the normal vasomotor tone and allows positive remodeling, simultaneously reducing the trigger for persistent inflammation and facilitating further interventions by percutaneous or surgical means. Absorb BVS® is the first generation everolimus-eluting poly-L-lactide (PLLA) bioresorbable scaffold. In recent meta-analyses Absorb BVS® was definitely proved to be safe and effective device in the treatment of symptomatic coronary artery disease. This was recently confirmed by FDA advisory panel of experts who recommended approval of the device based on an analysis of its risks and rewards. Nevertheless, still there are some concerns regarding stent thrombosis, and the real vessel functionality restoration at long-term observation. Worth mentioning is the fact that apart from stable coronary disease Absorb BVS® is used successfully in a series of off-label clinical settings such as acute coronary syndromes including STEMI, in-stent restenosis, coronary bifurcations, left main stenting or chronic total occlusions. Moreover, new bioresorbable scaffolds are under development with DEsolve® and DREAM 2G®, which are the most advanced.

  10. How to Prevent Vascular Disease

    Science.gov (United States)

    ... our CEO Board of Directors Scientific Advisory Board History of Vascular Cures Impact Contact Us Vascular Disease What is Vascular Disease? Education and Awareness Vascular Diseases Abdominal Aortic Aneurysm Aortic ...

  11. Post-biliary sphincterotomy bleeding despite covered metallic stent deployment

    Science.gov (United States)

    Donatelli, Gianfranco; Cereatti, Fabrizio; Dumont, Jean-Loup; Dhumane, Parag; Tuszynski, Thierry; Vergeau, Bertrand Marie; Meduri, Bruno

    2016-01-01

    Objectives: Several endoscopic techniques have been proposed for the management of post-sphincterotomy bleeding. Lately, self-expandable metal stents deployment has gained popularity especially as a rescue therapy when other endoscopic techniques fail. Methods-results: We report the case report of a massive post-sphincterotomy bleeding in a patient with a self-expandable metal stent in the biliary tree. Despite the presence of a correctly positioned self-expandable metal stent, a new endoscopic session was required to control the bleeding. Conclusions: Self-expandable metal stent may be useful to manage post-endoscopic sphincterotomy bleeding. However, up to now there is no specifically designed self-expandable metal stent for such complication. Large new designed self-expandable metal stent may be a useful tool for biliary endoscopist. PMID:27489716

  12. Percutaneous antegrade ureteric stent removal using a rigid alligator forceps.

    LENUS (Irish Health Repository)

    Given, M F

    2008-12-01

    To evaluate the safety and efficacy of percutaneous antegrade ureteric stent removal using a rigid alligator forceps. Twenty patients were included in our study. Indications for ureteric stent insertion included stone disease (n = 7), malignancy (n = 8) and transplant anastomotic strictures (n = 5). Stent retrieval was carried out for proximal stent placement\\/migration in seven patients and encrustation in the remaining 13. Twenty-two stents were successfully retrieved in 20 patients. There was one technical failure (5%). There were no major complications. We had four minor complications, which included nephrostomy site pain (n = 2), periprocedural sepsis (n = 1) and a small urinoma (n = 1). All patients settled with conservative management. Percutaneous radiologically guided antegrade ureteric stent removal with an alligator forceps is safe and effective, particularly when initial surgical removal has failed.

  13. Endeavour zotarolimus-eluting stent reduces stent thrombosis and improves clinical outcomes compared with cypher sirolimus-eluting stent : 4-year results of the PROTECT randomized trial

    NARCIS (Netherlands)

    Wijns, William; Steg, Ph. Gabriel; Mauri, Laura; Kurowski, Volkhard; Parikh, Keyur; Gao, Runlin; Bode, Christoph; Greenwood, John P.; Lipsic, Erik; Alamgir, Farqad; Rademaker-Havinga, Tessa; Boersma, Eric; Radke, Peter; van Leeuwen, Frank; Camenzind, Edoardo

    2014-01-01

    Aims To compare the long-term clinical safety between two drug-eluting stents with different healing characteristics in the Patient Related Outcomes with Endeavour (E-ZES) vs. Cypher (C-SES) Stenting Trial (PROTECT). At 3 years, there was no difference in the primary outcome of definite or probable

  14. Nitrogen-rich coatings for promoting healing around stent-grafts after endovascular aneurysm repair.

    Science.gov (United States)

    Lerouge, Sophie; Major, Annie; Girault-Lauriault, Pierre-Luc; Raymond, Marc-André; Laplante, Patrick; Soulez, Gilles; Mwale, Fackson; Wertheimer, Michael R; Hébert, Marie-Josée

    2007-02-01

    Complications following endovascular aneurysm repair (EVAR) are related to deficient healing around the stent-graft (SG). New generations of SG with surface properties that foster vascular repair could overcome this limitation. Our goal was to evaluate the potential of a new nitrogen-rich plasma-polymerised biomaterial, designated PPE:N, as an external coating for polyethylene terephtalate (PET)- or polytetrafluoro-ethylene (PTFE)-based SGs, to promote healing around the implant. Thin PPE:N coatings were deposited on PET and PTFE films. Then, adhesion, growth, migration and resistance to apoptosis of vascular smooth muscle cells (VSMCs) and fibroblasts, as well as myofibroblast differentiation, were assessed in vitro. In another experimental group, chondroitin sulphate (CS), a newly described mediator of vascular repair, was added to normal culture medium, to search for possible additional benefit. PPE:N-coatings, especially on PET, increased and accelerated cell adhesion and growth, compared with control PET and with standard polystyrene culture plates (PCP). PPE:N was also found to increase the resistance to apoptosis in VSMC, an important finding as aneurysms are characterised by VMSC depletion caused by a pro-apoptotic phenotype. Addition of CS in solution further increased migration and resistance to apoptosis. In conclusion, PPE:N-coating and/or CS could promote vascular repair around SGs following EVAR. PMID:17129601

  15. Detection of Postcoronary Stent Complication: Utility of 64-Slice Multidetector CT

    Directory of Open Access Journals (Sweden)

    Alpa Bharati

    2012-01-01

    Full Text Available Coronary stent fracture is a known complication of coronary arterial stent placements. Multiple long-term risks are also associated with drug eluting stents. 64-slice multidetector CT (MDCT coronary angiography has been shown to detect poststent complications such as instent stenosis, thrombosis, stent migration and stent fractures. We report a case of stent fracture in a patient who underwent RCA stenting with associated RCA perforation and almost complete thrombosis of the RCA and peristent fibrinoid collection. This is a rare case of stent fracture with perforation of the RCA. The paper highlights the role of 64-row multidetector computed tomography (MDCT in evaluation of such poststent placement complications.

  16. Long-term effect of stent placement in 115 patients with Budd-Chiari syndrome

    Institute of Scientific and Technical Information of China (English)

    Chun-Qing Zhang; Li-Na Fu; Lin Xu; Guo-Quan Zhang; Tao Jia; Ji-Yong Liu; Cheng-Yong Qin; Ju-Ren Zhu

    2003-01-01

    AIM: To report the long-term effect of stent placement in 115 patients with Budd-Chiari syndrome (BCS).METHODS: One hundred and fifteen patients with BCS were treated by percutaneous stent placement. One hundred and two patients had IVC stent placement, 30 patients had HV stent placement, 17 of them underwent both IVC stent and HV stent. All the procedures were performed with guidance of ultrasound.RESULTS: The successful rates in placing IVC stent and HV stent were 94 % (96/102) and 87 % (26/30), respectively.Ninety-seven patients with 112 stents (90 IVC stents, 22 HV stents) were followed up. 96.7 %(87/90) IVC stents and 90.9 %(20/22) HV stents remained patent during follow up periods (mean 49 months, 45 months, respectively). Five of 112 stents in the 97 patients developed occlusion. Absence of anticoagulants after the procedure and types of obstruction (segmental and occlusive) before the procedure were related to a higher incidence of stent occlusion.CONCLUSION: Patients with BCS caused by short length obstruction can be treated by IVC stent placement, HV stent placement or both IVC and HV stent placement depending on the sites of obstruction. The long-term effect is satisfactory.Anticoagulants are strongly recommended after the procedure especially for BCS patients caused by segmental occlusion.

  17. Severe destruction of urethral lumen after wall stent implantation. Unusual radiological findings; Schwere Obliteration des Harnroehrenlumens nach Wall-Stent-Implantation. Eine ungewoehnliche radiologische Besonderheit

    Energy Technology Data Exchange (ETDEWEB)

    Ragozzino, A. [II Servizio di Radiologia, Azienda Autonoma di Rilievo Nazionale A. Cardarelli, Napoli (Italy); Testa, G. [XV Div. di Urologia, Azienda Autonoma di Rilievo Nazionale A. Cardarelli, Napoli (Italy); De Ritis, R. [II Servizio di Radiologia, Azienda Autonoma di Rilievo Nazionale A. Cardarelli, Napoli (Italy); Diettrich, A. [II Servizio di Radiologia, Azienda Autonoma di Rilievo Nazionale A. Cardarelli, Napoli (Italy); Tuccillo, M. [II Servizio di Radiologia, Azienda Autonoma di Rilievo Nazionale A. Cardarelli, Napoli (Italy)

    1997-07-01

    The treatment of urethral stricture is still a challenge for urologists. Irrespective of the treatment employed, urethral stricture recurs in about 30% of all cases. In recent years, the wall stent, originally conceived for vascular surgery, has proved to be effective for the treatment of bulbar urethral strictures. The results are good, morbidity and complications occur only occasionally. In this paper, we described the case of a young patient who suffered from complete occlusion of the prosthesis 8 months after its implantation. The low age of the patient and the X-ray features of this case are unusual. The obstruction was successfully resolved by endoscopic resection. Follow-up after 14 months revealed a mild, short stenosis of the proximal tip. (orig.) [Deutsch] Die Behandlung der Harnroehrenverengung wird auf ca. 30% aller Faelle geschaetzt, unabhaengig von den angewandten Behandlungsmethoden. In den letzten Jahren wurde die Wall-Stent-Prothese, die urspruenglich fuer die Gefaesschirurgie beabsichtigt war, erfolgreich in der Behandlung von bulbaeren Harnroehrenverengungen eingesetzt. Die Resultate waren befriedigend; Morbiditaet und Komplikationen waren nur gelegentlich zu verzeichnen. In dieser Arbeit wollen wir den Fall eines Patienten beschreiben, der an einer vollstaendigen Okklusion des Harnroehrenlumens litt, dessen Auftreten sich 8 Monate nach der Implantation der Prothese zeigte. Das junge Alter des Patienten und die roentgologische Besonderheit sind ungewoehnliche Elemente fuer diesen Fall. Die Obstruktion wurde erfolgreich mittels endoskopischer Resektion behandelt. Nach 14 Monaten zeigte die Follow-up-Untersuchung eine leichte, kurze Stenose der proximalen Prothesenspitze. (orig.)

  18. Multifocal vascular lesions.

    Science.gov (United States)

    Levin, Laura E; Lauren, Christine T

    2016-03-01

    Multifocal vascular lesions are important to recognize and appropriately diagnose. Generally first noticed on the skin, multifocal vascular lesions may have systemic involvement. Distinguishing among the different types of multifocal vascular lesions is often based on clinical features; however, radiological imaging and/or biopsy are frequently needed to identify distinct features and guide treatment. Knowledge of the systemic associations that can occur with different vascular anomalies may reduce life-threatening complications, such as coagulopathy, bleeding, cardiac compromise, and neurologic sequelae. This review provides a synopsis of the epidemiology, pathogenesis, presentation, workup, and treatment of several well-recognized multifocal vascular tumors and malformations. PMID:27607324

  19. PREVENTION OF BIOFILM FORMATION ON NORFLOXACINMETRONIDAZOLE TREATED URETERAL LATEX STENTS

    OpenAIRE

    B. ELAYARAJAH; R. RAJENDRAN,; B. VENKATRAJAH,; WEDA SREEKUMAR,; ASASUDHAKAR,; P. K. JANIGA

    2011-01-01

    Biomaterial-associated bacterial infections present common and challenging complications with medical implants. The purpose of this study was to determine the antibacterial properties of latex rubber stents with integrated norfloxacin-metronidazole (synergistic antibacterial agent combinations) for the first time in order to prevent the colonization and biofilm formation on the surface of ureteral stents. Treating of latex rubber stents were carried out by adding the norfloxacin-metronidazole...

  20. Tailor made degradable ureteral stents from natural origin polysaccharides

    OpenAIRE

    Barros, Alexandre A.; Duarte, Ana Rita C.; Pires, R. A.; Lima, Estêvão Augusto Rodrigues de; Mano, J.F; Reis, R. L.

    2013-01-01

    A urinary stent is defined as a thin tube, which is inserted in the ureter to prevent or treat the obstruction of urine flow from the kidney. Silicone, latex, polyvinylchloride and polyurethanes are the most widely used materials for the preparation of stents. Nonetheless, severe clinical complications may result from the use of these materials such as fracture, encrustation and infection. In some of the cases, the ureteral stents are temporary and it is often required a second surgery to rem...

  1. Stent-graft repair of carotid endarterectomy-related pseudoaneurysm

    Institute of Scientific and Technical Information of China (English)

    Manuela Carnini; Gabriele Piffaretti; Chiara Lomazzi

    2013-01-01

    Objective: Carotid endarterectomy-related pseudoaneurysms are rare lesions challenging to be treated with conventional open surgery. Endovascular stent-graft has been rarely adopted with encouraging results. We present a case of a huge carotid pseudoaneurysm treated with a stent-graft and managed with a stent-graft and reviewed the available literature on the management and results of this technique for these challenging lesions.

  2. Pseudoaneurisme på arteria carotis interna behandlet med stent

    DEFF Research Database (Denmark)

    Benian, Cemil; Wagner, Aase; Cortsen, Marie

    2013-01-01

    Extracranial internal carotid artery aneurysms (EACIAs) are rare. Untreated they have a high stroke rate. Traditionally the treatment has been surgery or endovascular intervention with coils. Both are associated with relatively high complication rates. Another treatment option is endovascular int...... intervention with covered stent, which provides one-step closure of the aneurysm. As in the case story it can be complicated with in-stent occlusion. Therefore we recommend balloon occlusion test before treatment of EACIAs with covered stent....

  3. ENDOSCOPIC STENT FOR PALLIATING MALIGNANT AND BENIGN BILIARY OBSTRUCTION

    Institute of Scientific and Technical Information of China (English)

    缪林; 范志宁; 季国忠; 文卫; 蒋国斌; 吴萍; 刘政; 黄光明

    2004-01-01

    Objective: To study the techniques of placement of memory alloy plating gold biliary stent and plastic stent for palliation of malignant and benign biliary obstruction, and to assess its clinical effectiveness. Methods: The patients in plastic stent group included paplilla of duodenum inflamational strictures (n=24), common bile duct inflammational inferior segment strictures (n=4), choledocholithiasis (n=5), bile leak (n=11), bile duct surgery injurey (n=7) and pancreatic carcinoma (n=1). The patients in plating gold stent group included common bile duct carcinoma (n=5) and pancreatic carcinoma (n=6). Under fluoroscopic guidance the stent was inserted into biliary obstruction sites from oral cavity in all cases. Complications, liver function and blood serum amylase were investigated during the study period. Results: Successful stent placement was achieved in all cases. After operation of 7 days, in gold biliary stent groups, the rates of decrease of blood serum total bilirubin, glutamic-pyruvic transaminase, r-glutamyl transpeptidase and alkaline phosphatase were 67.16%, 58.37%, 40.63% and 41.54% respectively. In plastic stent group, the rates of decrease of STB, ALT, r-GT and AKP were 53.24%, 55.03%, 37.15%, 34.12% respectively. Early complication included post-ERCP pancreatitis and cholangititis. Occlusion of stent was the major late complication. Conclusion: Memory alloy plating gold biliary stent and plastic stent were safe and efficacious methods for malignant and benign biliary obstruction, and could improve patient's living quality. Plastic stent was an efficient complement for therapy of bile leak and bile duct injury.

  4. Fabrication of a Knitted Biodegradable Stents for Tracheal Regeneration

    Institute of Scientific and Technical Information of China (English)

    李毅; 张佩华; 冯勋伟

    2004-01-01

    Endoluminal stents for reinforcement and regeneration of human trachea have been developed by weft-knitting method on a small-diameter circular knitting machine. The constituent materials of the stent are Polyglactin, Polypropylene and Chitosan with Polyglactin and Polypropylene plate-stitched fabric acting as backbone while chitosan as matrix, respectively. The fabrication procedures including knitting and coating are described in this paper. Mechanical and animal tests have been carried out to evaluate the mechanical properties of the stents.

  5. Transanal stent in anterior resection does not prevent anastomotic leakage

    DEFF Research Database (Denmark)

    Bülow, Steffen; Bulut, O; Christensen, Ib Jarle;

    2006-01-01

    OBJECTIVE: A defunctioning transanal stent may theoretically reduce the leakage rate after anterior rectal resection. We present a randomized open study with the aim of comparing the leakage rate after anterior resection with a loop ileostomy, a transanal stent, both or neither. PATIENTS AND METH....... On this basis it was decided to discontinue the study prematurely for ethical reasons. CONCLUSION: Decompression of the anastomosis with a transanal stent does not reduce the risk of anastomotic leakage after anterior resection....

  6. Midterm Outcome of Femoral Artery Stenting and Factors Affecting Patency

    OpenAIRE

    Yu, Jae Seoung; Park, Keun-Myoung; Jeon, Yong Sun; Cho, Soon Gu; Hong, Kee Chun; Shin, Woo Young; Choe, Yun-Mee; Shin, Seok-Hwan; Kim, Kyung Rae

    2015-01-01

    Purpose: The purpose of this study was to evaluate the early and midterm results of superficial femoral artery (SFA) stenting with self-expanding nitinol stents and to identify the factors affecting patency. Materials and Methods: SFA stenting was performed in 165 limbs of 117 patients from January 2009 to December 2013. Patients were followed-up for the first occurrence of occlusion or stenosis based on computed tomography and duplex scan results and a decrease in ankle brachial index of >15...

  7. An investigation into stent expansion using numerical and experimental techniques

    OpenAIRE

    Toner, Deborah

    2009-01-01

    Extensive finite element analyses have been carried out by researchers to investigate the difference in the mechanical loading induced in vessels stented with various different stent designs and the influence of this loading on restenosis outcome. This study investigates the experimental validation of these numerical stent expansions using compliant mock arteries. The development of this in-vitro validation test has the prospect of providing a fully validated preclinical testing tool which ca...

  8. Drug eluting stents: are human and animal studies comparable?

    OpenAIRE

    Virmani, R; Kolodgie, F D; Farb, A.; Lafont, A

    2003-01-01

    Animal models of stenting probably predict human responses as the stages of healing are remarkably similar. What is characteristically different is the temporal response to healing, which is substantially prolonged in humans. The prevention of restenosis in recent clinical trials of drug eluting stents may represent a near absent or incomplete phase of intimal healing. Continued long term follow up of patients with drug eluting stents for major adverse cardiac events and angiographic restenos...

  9. Safety and efficacy of everolimus-eluting stents for bare-metal in-stent restenosis

    Energy Technology Data Exchange (ETDEWEB)

    Ota, Hideaki [Division of Interventional Cardiology, MedStar Washington Hospital Center, Washington, DC 20010 (United States); Mahmoudi, Michael [University of Surrey, Guildford Road, Surrey, GU2-7XH (United Kingdom); Torguson, Rebecca; Satler, Lowell F.; Suddath, William O.; Pichard, Augusto D. [Division of Interventional Cardiology, MedStar Washington Hospital Center, Washington, DC 20010 (United States); Waksman, Ron, E-mail: ron.waksman@medstar.net [Division of Interventional Cardiology, MedStar Washington Hospital Center, Washington, DC 20010 (United States)

    2015-04-15

    Objective: The aim of this study was to compare the safety and efficacy of the everolimus-eluting stents (EES) with the paclitaxel-eluting stent (PES) and sirolimus-eluting stent (SES) for the treatment of bare-metal in-stent restenosis. Background: The optimal treatment for bare-metal in-stent restenosis remains controversial. Methods: The study cohort comprised 322 consecutive patients (543 lesions) who presented with bare-metal in-stent restenosis to our institution and underwent coronary artery stent implantation with EES (114 patients; 181 lesions), PES (65 patients; 116 lesions) and SES (143 patients; 246 lesions). The analyzed clinical parameters were the 1-year rates of death, Q-wave myocardial infarction (MI), target lesion revascularization (TLR), target vessel revascularization (TVR), definite stent thrombosis (ST) and major adverse cardiac events (MACE) defined as the composite of death, MI, or TLR at 1-year. Results: The three groups were well matched for the conventional risk factors except for age and chronic kidney disease. The 1-year analyzed clinical parameters were similar in the three groups: death (EES = 3.5%, PES = 4.6%, SES = 4.2%; p = 0.94), MI (EES = 3.5%, PES = 6.3%, SES = 2.1%; p = 0.31), TLR (EES = 9.8%, PES = 9.5%, SES = 5.7%; p = 0.42), TVR (EES = 14.3%, PES = 11.1%, SES = 11.3%; p = 0.74), definite ST (EES = 0.9%, PES = 3.1%, SES = 3.5%; p = 0.38) and MACE (EES = 14.0%, PES = 15.4%, SES = 10.5%; p = 0.54). Male gender (hazard ratio = 0.47; 95% confidence interval = 0.25–0.88) and number of treated lesions (hazard ratio = 1.47; 95% confidence interval = 1.06–2.05) were found to be independent predictors of MACE. Conclusion: The results of the present study indicate that EES may provide similar safety and efficacy as first generation DES for the treatment of patients presenting with bare-metal in-stent restenosis.

  10. Comparison of neointimal morphology of in-stent restenosis with sirolimus-eluting stents versus bare metal stents: virtual histology-intravascular ultrasound analysis.

    Science.gov (United States)

    Yamamoto, Yoshihiro; Otani, Hajime; Iwasaka, Junji; Park, Haengnam; Sakuma, Takao; Kamihata, Hiroshi; Iwasaka, Toshiji

    2011-09-01

    Sirolimus-eluting stents (SES) have reduced the incidence of restenosis and target lesion revascularization compared to bare metal stents (BMS). However, inhibition of endothelialization and neointimal formation after SES implantation may produce vulnerable plaques. The present study compared the neointimal morphology of in-stent restenosis (ISR) between SES and BMS using virtual histology-intravascular ultrasound (VH-IVUS). Thirty ISR lesions (SES n = 15, BMS n = 15) demonstrated by coronary angiography in 30 patients with stable angina pectoris were analyzed with VH-IVUS between 6 months to 3 years after stent implantation. Tissue maps were reconstructed from radiofrequency data using VH-IVUS software. ISR lesions after SES implantation consisted of a significantly increased necrotic core (NC) compared to BMS (12.9 vs. 5.6% of neointimal volume, p stent thrombosis after SES implantation.

  11. Comparison of sirolimus-eluting stent versus polyzene-F polymer-coated stent in terms of early inflammatory response and long term outcomes

    OpenAIRE

    Murat Yuksel; Zeki Şimşek; Göksel Açar; Ulaankhuu Batgerel; Hacı Murat Güneş; Ali Metin Esen; Mehmet Muhsin Türkmen

    2015-01-01

    Objective: The intra-coronary stents provided great benefit after percutaneous transluminal coronary angioplasty (PTCA); however, high in-stent restenosis rates, even up to 25-30%, is the the main concern. Cytotoxic drug-eluting stents were developed to overcome this challenge. Whereas, they interfered vessel healing and endothelization process which led to increased risk of stent thrombosis. A bioinert molecule, polyzene-F(PzF), was applied to the surface of a new generation stent to provide...

  12. Stenting plus coiling: dangerous or helpful?; Stenting plus Coiling bei akut rupturierten intrakraniellen Aneurysmen

    Energy Technology Data Exchange (ETDEWEB)

    Wanke, I.; Gizewski, E.; Doerfler, A.; Stolke, D.; Forsting, M. [Essen Univ. (Germany). Inst. fuer Radiologie und Neuroradiologie

    2005-09-01

    Purpose: the purpose of this study was to evaluate the procedural risk of treating acute ruptured aneurysms with a stentcoil combination. Material and methods: between August 2001 and January 2004 we treated nine acute subarachnoid hemorrhage (SAH) patients with a combination of stents and platinum coils. Results: six aneurysms were 100% eliminated; the residual three aneurysms had a 95% to 99% occlusion. A transient thrombosis in the stent in one patient could be recanalized by intravenous application of ReoPro {sup registered}. In another patient an occlusive vasospasm at the distal end of the stent was successfully treated with intraarterial Nimotop {sup registered}. Neurological complications occurred in none of the patients. Conclusion: in broad-based aneurysms which cannot be clipped or in which any neurosurgical treatment presents an unacceptably high risk (posterior circulation and paraophthalmic aneurysms), treatment using a combination of stent and platinum coils might be an option even in the acute phase of an SAH. Platelet aggregation can be treated with Aspirin registered and Plavix {sup registered} after placement of the first coil, vasospasms with intraarterial Nimotop {sup registered}, and acute stent thrombosis with GP IIa/IIIb-antagonists. (orig.)

  13. Incidence of hemodynamic depression after carotid artery stenting using different self-expandable stent types

    International Nuclear Information System (INIS)

    The rates of hemodynamic depression (HD) and thromboembolism were compared in 95 carotid artery stenting (CAS) procedures performed in 87 patients with severe carotid artery stenosis using self-expandable braided Elgiloy stents (Wallstent) in 52 and slotted-tube Nitinol stents (Precise) in 43 procedures. The blood pressure, pulse rate, and neurological signs were recorded at short intervals during and after CAS. All patients underwent diffusion-weighted magnetic resonance imaging within 5 days after the procedure. The incidences of hypotension, bradycardia, and both were 17.9%, 3.2%, and 11.6%, respectively. The rate of postprocedural HD was 23.1% with Wallstent and 44.2% with Precise; the difference was significant (p=0.025). No patient manifested major cardiovascular disease after CAS. Diffusion-weighted magnetic resonance imaging revealed thromboembolism after 26.9% and 34.9% of Wallstent and Precise stent placement procedures, respectively; the difference was not significant. The type of self-expandable stent placed may affect the risk of procedural HD in patients undergoing CAS. Postprocedural HD was resolved successfully by the administration of vasopressors and by withholding antihypertensive agents. (author)

  14. [Endarterectomy more favourable than stenting in symptomatic significant carotid stenosis: higher risk of ischaemic stroke or death following stenting].

    Science.gov (United States)

    Meerwaldt, Robbert; Beuk, Roland J; Huisman, Ad B; Manschot, Sanne M; Zeebregts, Clark J; Geelkerken, Robert H

    2011-01-01

    Carotid endarterectomy (CEA) has proven its value in the treatment of patients with recent significant carotid artery stenosis. Percutaneous transluminal angioplasty with carotid artery stenting ('stenting' in short) is an alternative to CEA. The results of stenting and CEA in patients with symptomatic significant carotid artery stenosis were evaluated in 9 prospective randomized controlled trials and 11 meta-analyses. Almost all of these trials failed to show superiority of stenting to CEA. According to the 4 largest and most recent studies in this field the risk of a stroke or death within 30 days after the intervention is considerably higher following stenting than following CEA. In the long run the results of stenting and CEA seem to be comparable. CEA remains the gold standard in treatment of significant carotid artery stenosis, in particular in patients older than 70.

  15. Percutaneous Endoluminal Bypass of Iliac Aneurysms with a Covered Stent

    International Nuclear Information System (INIS)

    To evaluate the feasibility of percutaneous treatment of iliac aneurysms, a covered stent was inserted in nine men suffering from common iliac artery aneurysms (six cases), external iliac aneurysms (one case), or pseudoaneurysms (two cases). Placement of the stent was successful in all patients. In one patient, an endoprosthesis thrombosed after 15 days, but was successfully treated by thrombolysis and additional stent placement. At the follow-up examinations (mean period 22 months) all stent-grafts had remained patent. No late leakage or stenosis was observed

  16. Endoscopic dacryocystorhinostomy with and without silicone stenting: A comparative study

    Directory of Open Access Journals (Sweden)

    K. Shashidhar

    2014-07-01

    Full Text Available Background and objectives: The objective of the present study is to compare the results of performing endonasal dacryocystorhinostomy for primary nasolacrimal duct obstruction with and without silicone stenting. Methods: This is a prospective randomized study including 57 patients who underwent 62 endonasal DCR procedures. 32 eyes underwent DCR with bicanalicular silicone stenting which was kept for 6 weeks. 30 eyes underwent DCR without stenting. Follow up was done for 6 months. Outcome of the surgery was noted as success in terms of complete relief from epiphora, patency of the ostium assessed by nasal endoscopy and lacrimal sac syringing. Results: The overall success rate for endoscopic endonasal DCR was 90.3%. Success rates were 93.7% with stenting and 86.7% without stenting. There was no statistical difference in the outcome of the two groups (p=0.4180. Complications noted were granulations, synechiae, periorbital edema and punctal trauma, with no difference in the frequency of occurrence in the two groups. Conclusion: There is no significant increase in the success rates of DCR on using silicone stenting. A selective stenting approach may be advocated, using stenting for specific indications. With proper technique and good follow up, stenting is not associated with any significant complications.

  17. Metallic stents for management of malignant biliary obstruction

    International Nuclear Information System (INIS)

    In patients with inoperable malignant biliary obstruction, percutaneous transhepatic biliary drainage (PTBD) has been the method of choice for palliative treatment. All patients except three had undergone PTBD, and the stents were placed 5-7 days after the initial drainage procedure. Three patients underwent stent placement on the same day of PTBD. External drainage catheter is converted to various types of tube endoprostheses with associated physiologic and psychologic benefits. Tube stents, however, have some problems such as migration, occlusion, and traumatic implantation procedure. We report our experiences and clinical results of percutaneous placement of metallic stents in 40 patients with malignant biliary obstruction

  18. Comparison of two stents in modifying cerebral aneurysm hemodynamics.

    Science.gov (United States)

    Kim, Minsuok; Taulbee, Dale B; Tremmel, Markus; Meng, Hui

    2008-05-01

    There is a general lack of quantitative understanding about how specific design features of endovascular stents (struts and mesh design, porosity) affect the hemodynamics in intracranial aneurysms. To shed light on this issue, we studied two commercial high-porosity stents (Tristar stent and Wallstent) in aneurysm models of varying vessel curvature as well as in a patient-specific model using Computational Fluid Dynamics. We investigated how these stents modify hemodynamic parameters such as aneurysmal inflow rate, stasis, and wall shear stress, and how such changes are related to the specific designs. We found that the flow damping effect of stents and resulting aneurysmal stasis and wall shear stress are strongly influenced by stent porosity, strut design, and mesh hole shape. We also confirmed that the damping effect is significantly reduced at higher vessel curvatures, which indicates limited usefulness of high-porosity stents as a stand-alone treatment. Finally, we showed that the stasis-inducing performance of stents in 3D geometries can be predicted from the hydraulic resistance of their flat mesh screens. From this, we propose a methodology to cost-effectively compare different stent designs before running a full 3D simulation. PMID:18264766

  19. Protein losing enteropathy secondary to a pulmonary artery stent

    International Nuclear Information System (INIS)

    A 2-year-old patient with hypoplastic left heart syndrome presented 6 months following Fontan completion with protein-losing enteropathy (PLE). He had undergone stent implantation in the left pulmonary artery after the Norwood procedure, followed by redilation of the stent prior to Fontan completion. Combined bronchoscopic and catheterization studies during spontaneous breathing confirmed left bronchial stenosis behind the stent, and diastolic systemic ventricular pressure during expiration of 25 mm Hg. We postulate that the stent acts as a valve, against which the patient generates high expiratory pressures, which are reflected in the ventricular diastolic pressure. This may be the cause of PLE

  20. Metallic stents for management of malignant biliary obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byung Hee; Do, Young Soo; Byun, Hong Sik; Kim, Kie Hwan; Chin, Soo Yil [Korea Cancer Center Hospital, Seoul (Korea, Republic of)

    1992-11-15

    In patients with inoperable malignant biliary obstruction, percutaneous transhepatic biliary drainage (PTBD) has been the method of choice for palliative treatment. All patients except three had undergone PTBD, and the stents were placed 5-7 days after the initial drainage procedure. Three patients underwent stent placement on the same day of PTBD. External drainage catheter is converted to various types of tube endoprostheses with associated physiologic and psychologic benefits. Tube stents, however, have some problems such as migration, occlusion, and traumatic implantation procedure. We report our experiences and clinical results of percutaneous placement of metallic stents in 40 patients with malignant biliary obstruction.

  1. Mechanical properties and in vitro degradation of bioresorbable knitted stents.

    Science.gov (United States)

    Nuutinen, Juha-Pekka; Välimaa, Tero; Clerc, Claude; Törmälä, Pertti

    2002-01-01

    The aim of this study was to characterize the mechanical properties and in vitro degradation of bioresorbable knitted stents. Each stent was knitted using a single self-reinforced fibre made out of either PLLA or 96L/4D PLA or 80L/20G PLGA. The mechanical and physical properties of the fibres and stents were measured before and after gamma sterilization, as well as during in vitro degradation. The mechanical properties of the knitted stents made out of bioresorbable fibres were similar to those of commercially available metallic stents. The knitting geometry (loop height) had a marked effect on the mechanical properties of the stents. The rate of in vitro degradation in mechanical and physical properties for the PLLA and 96L/4D PLA stents was similar and significantly lower than that of the 80L/20G PLGA stents. The 80L/20G PLGA stents lost about 35% of their initial weight at 11 weeks. At this time, they had lost all their compression resistance strength. These data can be used as a guideline in planning further studies in vivo. PMID:12555898

  2. Protein losing enteropathy secondary to a pulmonary artery stent

    Directory of Open Access Journals (Sweden)

    Narayanswami Sreeram

    2012-01-01

    Full Text Available A 2-year-old patient with hypoplastic left heart syndrome presented 6 months following Fontan completion with protein-losing enteropathy (PLE. He had undergone stent implantation in the left pulmonary artery after the Norwood procedure, followed by redilation of the stent prior to Fontan completion. Combined bronchoscopic and catheterization studies during spontaneous breathing confirmed left bronchial stenosis behind the stent, and diastolic systemic ventricular pressure during expiration of 25 mm Hg. We postulate that the stent acts as a valve, against which the patient generates high expiratory pressures, which are reflected in the ventricular diastolic pressure. This may be the cause of PLE.

  3. Long-term effects of biodegradable versus durable polymer-coated sirolimus-eluting stents on coronary arterial wall morphology assessed by virtual histology intravascular ultrasound

    Institute of Scientific and Technical Information of China (English)

    LIU Hui-liang; ZHANG Jiao; JIN Zhi-geng; LUO Jian-ping; MA Dong-xing; YANG Sheng-li; LIU Ying; HAN Wei; JING Li-min; MENG Rong-ying

    2011-01-01

    Background The durable presence of polymer coating on drug-eluting stent (DES) surface may be one of the principal reasons for stent thrombosis. The long-term coronary arterial response to biodegradable polymer-coated sirolimus-eluting stent (BSES) in vivo remained unclear.Methods Forty-one patients were enrolled in this study and virtual histology intravascular ultrasound (VH-IVUS) was performed to assess the native artery vascular responses to BSES compared with durable polymer-coated SES (DSES) during long-term follow-up (median: 8 months). The incidence of necrotic core abutting to the lumen was evaluated at follow-up.Results With similar in-stent late luminal loss (0.15 mm (0.06-0.30 mm) vs. 0.19 mm (0.03-0.30 mm), P=0.772), the overall incidence of necrotic core abutting to the lumen was significantly less in BSES group than in DSES group (44% vs.63%, P <0.05) (proximal 18%, stented site 14% and distal 12% in BSES group, proximal 19%, stented site 28% and distal 16% in DSES group). The DSES-treated segments had a significant higher incidence of necrotic core abutting to the lumen through the stent struts (73% vs. 36%, P <0.01). In addition, more multiple necrotic core abutting to the lumen was observed in DSES group (overall: 63% vs. 36%, P <0.05). Furthermore, when the stented segments with necrotic core abutting to the lumen had been taken into account only, DSES-treated lesions tended to contain more multiple necrotic core abutting to the lumen through the stent struts than BSES-treated lesions (74% vs. 33%), although there was no statistically significant difference between them (P=0.06).Conclusions By VH-IVUS analysis at follow-up, a greater frequency of stable lesion morphometry was shown in lesions treated with BSESs compared with lesions treated with DSESs. The major reason was BSES produced less toxicity to the arterial wall and facilitated neointimal healing as a result of polymer coating on DES surface biodegraded as time went by.

  4. Firebird sirolimus eluting stent versus bare mental stent in patients with ST-segment elevation myocardial infarction

    Institute of Scientific and Technical Information of China (English)

    GAO Hai; YAN Hong-bing; ZHU Xiao-ling; LI Nan; AI Hui; WANG Jian; LI Shi-ying; YANG Duo

    2007-01-01

    Background There are few evidences about the value of drug eluting stent in patients with ST-segment elevation myocardial infarction (STEMI). We prospectively designed a randomized controlled trial to compare the safety and efficacy of Firebird sirolimus eluting stent (Firebird stent) and bare metal stent (BMS).Methods Patients with STEMI enrolled during one year period were randomized to undergo implantation of Firebird stent or BMS, and clinical and angiographic follow-up. The primary endpoint of the present study was in-lesion late lumen loss (LLL) at 6 months, and secondary endpoint includes stent thrombosis and major adverse cardiac events (MACE) at 6 months.Results During one year period, 156 patients were randomized into the Firebird stent group (101 patients with an average age of 57.8 years) or the BMS group (55 patients with 59.7 years on average). Six-month angiographic follow-up was available in 66.3% and 63.7% of patients assigned to Firebird stent and BMS, respectively. At 6-month follow-up,mortality, target vessel revascularization (TVR) and MACE were 2.0%, 6.9% and 9.9% in the Firebird stent group, while 3.6%, 30.9% and 36.4% in the BMS group (P<0.05). Subacute thrombosis occurred in 1 patient in both groups,respectively. The mean LLL was 0.18 mm in the Firebird stent group versus 0.72 mm in the BMS group.Conclusion Implantation of Firebird sirolimus eluting stent for STEMI may greatly reduce TVR and MACE at 6 months with low incidence of acute/subacute stent thrombosis compared with BMS.

  5. Usefulness of surgical closure following intraoperative endoscopic additional stenting of duodenal perforation by stent: Report of a case

    OpenAIRE

    Shimizu, Kenji; Takamori, Hiroshi; Baba, Hideo

    2016-01-01

    Introduction Malignant duodenal stenosis occurs in patients with advanced periampullary cancer. Insertion of a self-expanding metal stent for the treatment of this condition carries the risk of subsequent perforation of the duodenum. We report successful treatment of duodenal perforation induced by a stent. Presentation of case An 80-year-old woman suffering from stenosis caused by advanced periampullary cancer underwent metallic stent placement and her symptoms improved. While attempting bil...

  6. A Comparative Study on the Efficacy of Covered Metal Stent and Plastic Stent in Unresectable Malignant Biliary Obstruction

    OpenAIRE

    Choi, Jae Myoung; Kim, Jin Hong; Kim, Soon Sun; Yu, Jun Hwan; Hwang, Jae Chul; Yoo, Byung Moo; Park, Sang Heum; Kim, Ho Gak; Lee, Dong Ki; Ko, Kang Hyun; Yoo, Kyo Sang; Park, Do Hyun

    2012-01-01

    Background/Aims The placement of self expandable metal stent (SEMS) is one of the palliative therapeutic options for patients with unresectable malignant biliary obstruction. The aim of this study was to compare the effectiveness of a covered SEMS versus the conventional plastic stent. Methods We retrospectively evaluated 44 patients with unresectable malignant biliary obstruction who were treated with a covered SEMS (21 patients) or a plastic stent (10 Fr, 23 patients). We analyzed the techn...

  7. Mechanical characteristics of novel polyester/NiTi wires braided composite stent for the medical application

    Science.gov (United States)

    Zou, Qiuhua; Xue, Wen; Lin, Jing; Fu, Yijun; Guan, Guoping; Wang, Fujun; Wang, Lu

    Stents have been widely used in percutaneous surgery to treat stenosis diseases. The braided NiTi stent, as a promising prototype, still has limitations of low radial force and loose structure. In the present study, a newly integrated composite stent was designed and braided with NiTi wires and polyester multifilament yarns by textile technology. The mechanical properties of four composite stents and the control bare NiTi stent were evaluated by in vitro compression, bending and anti-torsion tests. The results showed that integrated polyester/NiTi composite stents were superior in radial support. The stents could keep patency even when highly curved and had lower stent straightening force. Composite stents with certain structure stayed stable under twisting. The configuration of NiTi wires in composite stents could significantly impact stent deformation under twisting.

  8. Billowing Of Endologix Powerlink Stent Mimicking Endoleaks

    Science.gov (United States)

    Wu, Alex; Karuppasamy, Karunakaravel; Wang, Weiping

    2016-01-01

    Introduction: Endoleaks remains one of the primary concerns of endovascular aortic aneurysm repair (EVAR) and is routinely followed with CT angiography (CTA). However, certain imaging findings can mimic endoleaks. Case Presentation: A 65-year-old woman who had endovascular aortic repair (EVAR) of an abdominal aortic aneurysm with Endologix Powerlink system developed marked new circumferential cauliflower-like bulging of contrast-filled sacs at mid-stent-graft with enlargement of the excluded aneurysm at 3-year follow-up. Conclusions: Considering the unique construct of the Powerlink stents, this is thought to represent aneurysmal degeneration of the outer fabric material from the metal struts and may potentially pressurize the excluded sac with risk for rupture. PMID:26949697

  9. Self-expanding metallic esophageal stents: A long way to go before a particular stent can be recommended

    Institute of Scientific and Technical Information of China (English)

    Pankaj Jain

    2011-01-01

    We agree that the covered self-expanding metal stents (SEMSs) fare better than the uncovered stents as recurrent dysphagia due to tumor ingrowth is common with uncovered stent. Recent American College of Gastroenterology Practice Guideline on the Role of Esophageal Stents in Benign and Malignant Diseases concludes that SEMSs cannot be routinely recommended in conjunction with chemo-radiation. The comparison of ultraflex and choostent in the Italian study found no difference in the palliation of dysphagia, rate of complications and survival rate.

  10. Rapid development of late stent malappositon and coronary aneurysm following implantation of a paclitaxel-eluting coronary stent

    Institute of Scientific and Technical Information of China (English)

    ZHANG Feng; QIAN Ju-ying; GE Jun-bo

    2007-01-01

    @@ Late stent malapposition (LSM), an unusual intravascular ultrasound (IVUS) finding at follow-up, has been reported to be more common after drug-eluting stent (DES) implantation than after bare metal stent(BMS) implantation.1-3 However, there has been no clear elucidation of time course and mechanism. We reported a case who developed LSM and coronary aneurysm very early after paclitaxel-eluting stent (PES) implantation. A review of the literature reveals no previous report describing rapid development of LSM and coronary aneurysm after PES implantation.

  11. Successful treatment of coronary artery pseudoaneurysm by graft stent, which developed after the implantation of bare metal stent

    Directory of Open Access Journals (Sweden)

    Utku Şenol

    2013-03-01

    Full Text Available Although coronary artery pseudoaneurysm which couldoccur following percutaneous coronary interventions is arare complication, it can be mortal. As soon as the pseudoaneurysmis diagnosed, it should be treated by percutaneousintervention or surgery. Graft stent implantationis a preferred treatment for appropriate patients. In thiscase report, we presented a successful treatment of coronaryartery pseudoaneurysm by graft stent; which developedafter the implantation of bare metal stent into theleft anterior descending coronary artery. J Clin Exp Invest2013; 4 (1: 126-129Key words: Coronary artery, pseudoaneurysm, graft stent

  12. Reperfusion hemorrhage following superior mesenteric artery stenting.

    LENUS (Irish Health Repository)

    Moore, Michael

    2012-02-03

    Percutaneous transluminal angioplasty and stent placement is now an established treatment option for chronic mesenteric ischemia and is associated with low mortality and morbidity rates. We present a case of reperfusion hemorrhage complicating endovascular repair of superior mesenteric artery stenosis. Although a recognized complication following repair of carotid stenosis, hemorrhage has not previously been reported following mesenteric endovascular reperfusion. We describe both spontaneous cessation of bleeding and treatment with coil embolization.

  13. Carotid Disease Management: Surgery, Stenting, or Medication.

    Science.gov (United States)

    Khandelwal, Priyank; Chaturvedi, Seemant

    2015-09-01

    Internal carotid artery stenosis accounts for about 7-10 % of ischemic strokes. Conventional risk factors such as aging, hypertension, diabetes mellitus, and smoking increase the risk for carotid atherosclerosis. All patients with carotid stenosis should receive aggressive medical therapy. Carotid revascularization with either endarterectomy or stenting can benefit select patients with severe stenosis. New clinical trials will examine the contemporary role of carotid revascularization relative to optimal medical therapy.

  14. Coated stents to prevent restenosis in coronary heart disease

    Directory of Open Access Journals (Sweden)

    Hagen, Anja

    2005-11-01

    Full Text Available Background: In-stent-restenosis (ISR is considered to be an essential limiting factor of stenting in coronary heart disease (CHD. The development of coated stents has raised expectations on substantial lowering restenosis after stenting with decreasing the rate of restenosis and a reduction in the rate of clinical events. Objectives: The present analysis addresses the questions on medical effectiveness and cost-effectiveness of the use of various coated stent types in CHD. Methods: The literature was searched in December 2004 in the most relevant medical and economic databases. The medical evaluation was conducted on the basis of published RCT. The data from the studies regarding various angiographic, sonographic and clinical endpoints were checked for methodical quality and summarised in meta-analyses. Within the scope of economic evaluation the primary studies were analysed and modelling was performed, applying clinical effect estimates from the meta-analyses of the medical evaluation and current estimates of German costs. Results: Medical evaluation: Ten different stenttypes were used in the included 26 RCT. The results for heparin, silicon-carbide, carbon and PTFE coated stenttypes could not reveal any significant differences between the medical effectiveness of coated and uncoated stents. The application of sirolimus, paclitaxel, everolimus and 7-hexanoyltaxol eluting stents showed a significant lower restenosis at 6-9 months with decrease in the rate of restenosis for polymer-based sirolimus, paclitaxel and 7-hexanoyltaxol eluting stents. In contrast, the use of gold-coated and actinomycin-D eluting stents was associated with a significantly higher restenosis. The polymer-based sirolimus and paclitaxel eluting stents also showed a significant and considerable reduction in the rate of repeated percutaneous revascularisations at 6-12 months (3.5% vs. 19.7%; p<0.0001, RR=0.19 [95%CI: 0.11; 0.33] and 3.5% vs. 12.2%; p<0.0001, RR=0.30 [95%CI: 0

  15. Asymmetric distances for binary embeddings.

    Science.gov (United States)

    Gordo, Albert; Perronnin, Florent; Gong, Yunchao; Lazebnik, Svetlana

    2014-01-01

    In large-scale query-by-example retrieval, embedding image signatures in a binary space offers two benefits: data compression and search efficiency. While most embedding algorithms binarize both query and database signatures, it has been noted that this is not strictly a requirement. Indeed, asymmetric schemes that binarize the database signatures but not the query still enjoy the same two benefits but may provide superior accuracy. In this work, we propose two general asymmetric distances that are applicable to a wide variety of embedding techniques including locality sensitive hashing (LSH), locality sensitive binary codes (LSBC), spectral hashing (SH), PCA embedding (PCAE), PCAE with random rotations (PCAE-RR), and PCAE with iterative quantization (PCAE-ITQ). We experiment on four public benchmarks containing up to 1M images and show that the proposed asymmetric distances consistently lead to large improvements over the symmetric Hamming distance for all binary embedding techniques.

  16. Chest pain following oesophageal stenting for malignant dysphagia

    Energy Technology Data Exchange (ETDEWEB)

    Golder, Mark; Tekkis, Paris P.; Kennedy, Colette; Lath, Sadaf; Toye, Rosemary; Steger, Adrian C

    2001-03-01

    AIM: The palliative use of self-expanding metallic stents has been widely reported to relieve dysphagia in cases of oesophageal carcinoma. Little has been documented on the severity of chest pain following oesophageal stenting. The aim of this study was to investigate the association of pain with oesophageal stenting for malignant dysphagia. METHODS: Fifty-two patients with inoperable oesophageal carcinoma underwent stent placement between 1995-1999. Daily opioid analgesic requirements (mg of morphine equivalent doses) were monitored for 3 days before and 7 days after stenting. The degree of palliation was expressed as a dysphagia score (0-3). Hospital stay, readmission days, stent complications and patient survival time were also recorded. RESULTS: Twenty-six patients (50%) required opioid analgesia for chest pain (median dose: 80 mg morphine/day) within 48 h of the procedure compared to 11 (21.2%) patients before stenting (P = 0.0041). A significant increase was evident in the analgesic consumption following stent deployment (P < 0.001). The dysphagia score improved by a median value of 1 (CI 0.25)P < 0.001, with a re-intervention rate of 11.5%. The median survival time was 40 days post stenting (range 1-120). CONCLUSION: A significant proportion of patients developed chest pain after oesophageal stenting, requiring high dose opioid analgesia. As the origin of the pain is still unknown, pre-emptive analgesia may a play role in reducing stent-related morbidity and possibly in-hospital stay. Golder, M. et al. (2001)

  17. Radiation dosimetry in developing a radioactive stent for therapeutic use

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Hee; Kim, Jang Hee; Chung, Wee Sup; Woo, Kwang Sun [Korea Cancer Center Hospital , Seoul (Korea, Republic of)

    1997-09-01

    Research Goal: A new radioation therapy protocol of the esophageal carcinoma has been proposed. A metal stent coated with beta-emitting radioisotope would be inserted into the lesion of malignant esophageal obstruction and irradiate it. In this study, dose to the esophageal wall is estimated to suggest the selection of radioisotope, total activity, and the activity distribution pattern over the stent. Result: Dose distribution of the esophageal wall is determined by the energy spectrum of beta particles emitted from the radioisotope used in the stent activation. The endpoint energy of the beta spectrum corresponds to a range in liquid water, which determines the depth into the esophageal wall where the dose is significant. With a stent of constant areal activity density, dose to the esophageal wall increases with an increasing stent height until reaching a saturation value. Dose is maximum at the esophageal wall surface. The degree of dose decreasing as the target moves into the esophageal wall varies among different radioisotopes. However, dose decreases by similar degree among different radioisotopes as the target moves from the stent central height toward the stent end. For a stent of 2 cm in diameter, more than 4 cm in heigh, and 10 {mu}Ci/cm{sup 2} in activity, dose at the esophageal wall surface and at the stent central height is {approx}70 Gy, {approx}60 Gy, {approx}50 Gy, {approx}50 Gy, {approx}25 Gy, and {approx}15 Gy for {sup 90}Y, {sup 188}Re, {sup 166}Ho, {sup 32}P, {sup 186}Re, and {sup 192}Ir, respectively. Applications: Dose estimates provided in this study and the experimental results from the researchers at Yonsei University, who applied the radioactive stent to animals, will be used to analyze the relationship between the stent design and the corresponding therapeutic effect. This helps utilizing the new protocol of treating the esophageal carcinoma. 37 refs., 18 tabs., 27 figs. (author)

  18. Endoscopic management of occluded metal biliary stents:Metal versus 10F plastic stents

    Institute of Scientific and Technical Information of China (English)

    Won; Jae; Yoon; Ji; Kon; Ryu; Jung; Won; Lee; Dong-Won; Ahn; Yong-Tae; Kim; Yong; Bum; Yoon; Sang; Myung; Woo; Woo; Jin; Lee

    2010-01-01

    AIM:To compare the efficacy of self-expandable metal stents(SEMSs) with 10F plastic stents(PSs) in the endoscopic management of occluded SEMSs.METHODS:We retrospectively reviewed the medical records of 56 patients who underwent SEMS insertion for palliation of unresectable malignant biliary obstruction between 2000 and 2007 and subsequent endoscopic retrograde biliary drainage(ERBD) with SEMS or PS for initial SEMS occlusion between 2000 and 2008.RESULTS:Subsequent ERBD with SEMS was performed in 29 patient...

  19. Prevention of Cerebrovascular Restenosis after Stenting%脑血管内支架置入术后再狭窄的预防

    Institute of Scientific and Technical Information of China (English)

    曹金英; 徐江涛

    2011-01-01

    Cerebrovascular stent restenosis is associated with the residual stenosis after stenting,the vessel diameter before treatment, diabetes, the number of stents. The dominant mechanisms of cerebrovascular stent restenosis are platelet activation and adhesion, inflammatory response and the induction by the inflammatory factors,vascular smooth muscle cells proliferation and migration,neointimal hyperplasia,and etc.. In recent years, with the development of research and application on operative techniques, stent materials, drugs, and etc. ,the rate of restenosis has decreased. Here is to review the prevention of cerebrovascular restenosis after stenting.%脑血管支架置入术后再狭窄与术后支架内残余狭窄程度、治疗前血管直径、糖尿病及支架置入数密切相关.脑血管支架置入术后再狭窄的发生机制主要有血小板的激活和黏附、炎性反应及炎性因子的诱导作用、血管平滑肌细胞的增殖和迁移、新生内膜的增生等.近年来,随着对手术操作技术、支架材料及药物等的不断研究与应用,再狭窄率有所下降.现对脑血管支架置入术后再狭窄的预防方法进行综述.

  20. Asymmetric Synthesis via Chiral Aziridines

    DEFF Research Database (Denmark)

    Tanner, David Ackland; Harden, Adrian; Wyatt, Paul;

    1996-01-01

    A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines)]. In the b......A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines...

  1. Ideal 3D asymmetric concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Botella, Angel [Departamento Fisica Aplicada a los Recursos Naturales, Universidad Politecnica de Madrid, E.T.S.I. de Montes, Ciudad Universitaria s/n, 28040 Madrid (Spain); Fernandez-Balbuena, Antonio Alvarez; Vazquez, Daniel; Bernabeu, Eusebio [Departamento de Optica, Universidad Complutense de Madrid, Fac. CC. Fisicas, Ciudad Universitaria s/n, 28040 Madrid (Spain)

    2009-01-15

    Nonimaging optics is a field devoted to the design of optical components for applications such as solar concentration or illumination. In this field, many different techniques have been used for producing reflective and refractive optical devices, including reverse engineering techniques. In this paper we apply photometric field theory and elliptic ray bundles method to study 3D asymmetric - without rotational or translational symmetry - concentrators, which can be useful components for nontracking solar applications. We study the one-sheet hyperbolic concentrator and we demonstrate its behaviour as ideal 3D asymmetric concentrator. (author)

  2. Incompressibility of asymmetric nuclear matter

    OpenAIRE

    Chen, Lie-Wen; Cai, Bao-Jun; Shen, Chun; Ko, Che Ming; Xu, Jun; Li, Bao-An(Department of Physics and Astronomy, Texas A&M University-Commerce, Commerce, TX, 75429-3011, USA)

    2009-01-01

    The incompressibility $K_sat(\\delta)$ of isospin asymmetric nuclear matter at its saturation density. Our results show that in the expansion of $K_sat(\\delta)$ in powers of isospin asymmetry $\\delta$, i.e., $K_sat(\\delta )$=K_{0}+K_{sat,2}\\delta^{2}+K_{sat,4}\\delta^{4}+O(\\delta^{6})$, the magnitude of the 4th-order K_{sat,4} parameter is generally small. The 2nd-order K_{sat,2} parameter thus essentially characterizes the isospin dependence of the incompressibility of asymmetric nuclear matte...

  3. Forces between asymmetric polymer brushes

    OpenAIRE

    Shim, D.F.K.; Cates, M. E.

    1990-01-01

    We study the equilibrium compression of asymmetric polymer brushes grafted on flat plates, under athermal and theta solvent conditions, using a lattice self-consistent field (SCF) approach. We find that the separation d between two plates coated asymmetrically with brushes of type 1 and 2, as a function of the force F, obeys the "bisection rule", d(F) = (d1(F) + d 2(F)) /2 where d1(F)and d 2(F) are the corresponding separations for the symmetric brushes of type 1 and 2 respectively.The bisect...

  4. Research on asymmetric "Jerusalem" unit

    Institute of Scientific and Technical Information of China (English)

    Jun Lu; Jianbo Wang

    2009-01-01

    An asymmetric Jerusalem unit and the frequency selective surface(FSS)structure composed of such units are designed.The transmittance of the designed FSS structure is calculated by mode-matching method and compared with the test results.The comparison results show that the FSS center frequency of the asymmetric structure unit drifts little with the variation of the incident angles of the electromagnetic waves and keeps relatively stable.The research offers a new choice for the application of FSS under the large scanning angle of electromagnetic waves.

  5. Vascularity in thyroid neoplasms

    DEFF Research Database (Denmark)

    Larsen, Karen Kjaer; Andersen, Niels Frost; Melsen, Flemming;

    2006-01-01

    The aim of the present study was to evaluate the reliability of four different methods (vascular grading, Chalkley count, microvessel density (MVD) and stereological estimation) for quantifying intratumoral microvascularity in thyroid neoplasms, by comparing the variability within and between...... count should be the preferred method for assessing microvascularity in thyroid neoplasms. The diagnostic evaluation revealed a tendency towards higher degree of vascularity in FA compared to both FC and PC for all methods. No statistically significant association was seen between vascular density and...

  6. Vascular cognitive impairment

    OpenAIRE

    Rebecca F. Gottesman; Hillis, Argye E.

    2014-01-01

    The term vascular cognitive impairment (VCI) has been proposed to encompass all people with cognitive impairment of cerebrovascular origin. VCI is not a single condition, but has several clinical presentations, etiologies, and treatment. VCI forms a spectrum that includes vascular dementia, mixed Alzheimer’s disease with a vascular component, and VCI that does not meet dementia criteria. Multiple pathophysiological mechanisms contribute to VCI, accounting for its heterogeneity. Although main ...

  7. Hemodynamic effects of stenting on wide-necked intracranial aneurysms

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-sen; LUO Bin; LI Chuan-hui; YANG Xin-jian; WANG Sheng-zhang; QIAO Ai-ke; CHEN Jia-liang; ZHANG Kun-ya; LIU Zhi-cheng; ZHAO Yu-jing; ZHANG Ying

    2010-01-01

    Background Stent placement has been widely used to assist coiling in cerebral aneurysm treatments. The present study aimed to investigate the hemodynamic effects of stenting on wide-necked intracranial aneurysms.Methods Three idealized plexiglass aneudsmal models with different geometries before and after stenting were created, and their three-dimensional computational models were constructed. Flow dynamics in stented and unstented aneurismal models were studied using in vitro flow visualization and computational fluid dynamics (CFD) simulations. In addition, effects of stenting on flow dynamics in a patient-specific aneurysm model were also analyzed by CFD.Results The results of flow visualization were consistent with those obtained with CFD simulations. Stent deployment reduced vortex inside the aneurysm and its impact on the aneurysm sac, and decreased wall shear stress on the sac.Different aneurysm geometries dictated fundamentally different hemodynamic patterns and outcomes of stenting.Conclusions Stenting across the neck of aneurysms improves local blood flow profiles. This may facilitate thrombus formation in aneurysms and decrease the chance of recanalization.

  8. Transhepatic approach for extracardiac inferior cavopulmonary connection stent fenestration.

    LENUS (Irish Health Repository)

    Kenny, Damien

    2012-02-01

    We report on a 3-year-old male who underwent transcatheter stent fenestration of the inferior portion of an extracardiac total cavopulmonary connection in the setting of hypoplastic left heart syndrome. Transhepatic approach, following an unsuccessful attempt from the femoral vein facilitated delivery of a diabolo-shaped stent.

  9. Endovascular retrieval of a prematurely deployed covered stent

    Institute of Scientific and Technical Information of China (English)

    Jefferson; T; Miley; Gustavo; J; Rodriguez; Ramachandra; P; Tummala

    2015-01-01

    Several techniques have been reported to address different endovascular device failures. We report the case of a premature deployment of a covered balloon mounted stent during endovascular repair of a posttraumatic carotid-cavernous fistula(CCF). A 50-year-old male suffered a fall resulting in loss of consciousness and multiple facial fractures. Five weeks later, he developed decreased left visual acuity, proptosis, chemosis, limited eye movements and cranial/orbit bruit. Cerebral angiography demonstrated a direct left CCF and endovascular repair with a 5.0 mm × 19 mm covered stent was planned. Once in the lacerum segment, increased resistance was encountered and the stent was withdrawn resulting in premature deployment. A 3 mm × 9 mm balloon was advanced over an exchange length microwire and through the stent lumen. Once distal to the stent, the balloon was inflated and slowly pulled back in contact with the stent. All devices were successfully withdrawn as a unit. The use of a balloon to retrieve a prematurely deployed balloon mounted stent is a potential rescue option if leaving the stent in situ carries risks.

  10. Innovations in Stroke Prevention: An Update on Carotid Stenting

    Medline Plus

    Full Text Available INNOVATIONS IN STROKE PREVENTION: AN UPDATE ON CAROTID STENTING NEW YORK-PRESBYTERIAN HOSPITAL NEW YORK, NY July 15, 2008 00:00: ... evening. Welcome to our webcast on innovations in stroke prevention: an update on carotid stenting. I'm ...

  11. Stent migration during transcatheter management of coarctation of aorta.

    Science.gov (United States)

    Kannan, Bhava R J; Srinivasan, Muthusamy

    2012-02-15

    A 13-year-old girl underwent endovascular stent placement for coarctation of aorta. The fully expanded stent migrated to ascending aorta which could be stabilized, recrimped, and repositioned with a 20-mm goose neck snare. Postdilatation was performed from the left brachial route resulting in a good outcome.

  12. Vessel healings after stenting with different polymers in STEMI patients

    Science.gov (United States)

    Jin, Qin-Hua; Chen, Yun-Dai; Tian, Feng; Guo, Jun; Jing, Jing; Sun, Zhi-Jun

    2016-01-01

    Background Different stents implantation in ST-segment elevation myocardial infarction (STEMI) patients may influence the long term prognosis by affecting vessel healings after stenting. The aim of this study was to evaluate the vessel healings after implantation of drug eluting stents (DES) with biodegradable or durable polymer or of bare-metal stents (BMS) in patients with acute STEMI. Methods This study included 50 patients, who underwent follow up angiogram and optical coherence tomography (OCT) assessment about one year after percutaneous coronary intervention (PCI) for STEMI. According to the initial stents types, these patients were classified to durable (n = 19) or biodegradable polymer sirolimus-eluting stents (n = 15), or BMS (n = 16) groups. The conditions of stent struts coverage and malapposition were analyzed with OCT technique. Results A total of 9003 struts were analyzed: 3299, 3202 and 2502 from durable or biodegradable polymer DES, or BMS, respectively. Strut coverage rate (89.0%, 94.9% and 99.3%, respectively), malapposition presence (1.7%, 0.03% and 0 of struts, respectively) and average intimal thickness over struts (76 ± 12 µm, 161 ± 30 µm and 292 ± 29 µm, respectively) were significantly different among different stent groups (all P < 0.001). Conclusions Vessel healing status in STEMI patients is superior after implantation of biodegradable polymer DES than durable polymer DES, while both are inferior to BMS. PMID:27403139

  13. A novel biodegradable esophageal stent: results from mechanical and animal experiments.

    Science.gov (United States)

    Liu, Jin; Shang, Liang; Liu, Jiyong; Qin, Chengyong

    2016-01-01

    Biodegradable esophageal stents eliminate stent retrieval, but usually induce hyperplasia. This study investigated the properties of a novel biodegradable stent in vitro and in vivo. The degradation of the novel stent was observed in phosphate buffered saline (PBS) for 8 weeks. The radial forces, pH values, morphology, and retention rate of the intrinsic viscosity (R[η]) of the new biodegradable stent were all evaluated. In vitro, the pH values remained constant for 4 weeks and declined from weeks 4 to 8. The biodegradable threads degraded and ruptured at 6 weeks. Consequently, the radial force of the stent decreased to zero at that time. The curve of R[η] decreased with time linearly in PBS. To study the stents in vivo, we used a stricture model in which the middle esophagus of rabbits was damaged by alkali burn. Stents were inserted 2 weeks after injury and observed for 8 weeks. We assessed complications related to stent insertion, degradation of the stent, and survival of the rabbits. Two stents migrated, and one rabbit died. In the other rabbits, two stents degraded and moved into the stomach during the sixth week, five during the seventh week and one during the eighth week, respectively. One stent remained in position until the end of the study. In conclusion, our newly designed stent retained the strong radial force of self-expandable metal stents (SEMSs) and maintained the biodegradable properties of biodegradable (BD) stents. PMID:27158397

  14. Effect of external stents on prevention of intimal hyperplasia in a canine vein graft model

    Institute of Scientific and Technical Information of China (English)

    ZOU Rong-jiang; ZOU Liang-jian; HUANG Sheng-dong; WANG Yin; HAN Lin; JI Guang-yu; XU Zhi-yun

    2007-01-01

    Background External stents have been used to reduce intimal hyperplasia of vein grafts.The aim of the present study was to define the size of an external stent appropriate for a particular graft by comparing vein grafts with different sizes of external stents.Methods A series of paired trials was performed to compare femoral vein grafts with different sizes of external stents,where 30 modeled canines were equally divided into three groups:6-mm external stent vs non-stent control,4-mm vs 6-mm external stent,and 4-mm vs 8-mm external stent.At day 3 after operation,color Doppler flow imaging(CDFI)was done to observe blood flow in the lumen.Four weeks later,CDFI was re-checked and the veins were harvested,stained and measured.Results All grafts were patent without formation of thrombosis.External stents significantly reduced intimal thickness of the vein grafts with a 6-mm external stent compared with the vein grafts without external stents(P<0.05).The vein grafts with the 4-mm external stent had similar intimal, medial and adventitial thicknesses compared with those with the 6-mm external stent and the 8-mm external stent.Conclusions External stents can reduce intimal hyperplasia of vein grafts.Stents of different diameters exert the similar effect on prevention of intimal hyperplasia.

  15. Renin-angiotensin system intervention to prevent in-stent restenosis - An unclosed chapter

    NARCIS (Netherlands)

    Langeveld, B; Roks, AJM; Tio, RA; Voors, AA; Zijlstra, F; van Gilst, WH

    2005-01-01

    The occurrence of in-stent restenosis is a major drawback of percutaneous transluminal coronary angioplasty with stent placement. Target vessel revascularization is necessary in 15% of patients who receive a stent. Recent advances in the development of drug-eluting stents have reduced these numbers

  16. Finite element analyses for design evaluation of biodegradable magnesium alloy stents in arterial vessels

    Energy Technology Data Exchange (ETDEWEB)

    Wu Wei [Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milan (Italy); Gastaldi, Dario, E-mail: dario.gastaldi@polimi.it [Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milan (Italy); Yang Ke; Tan Lili [Division of Specialized Materials and Devices, Institute of Metal Research, Chinese Academy of Sciences, Shenyang (China); Petrini, Lorenza; Migliavacca, Francesco [Laboratory of Biological Structure Mechanics, Structural Engineering Department, Politecnico di Milano, Piazza Leonardo da Vinci, 32, 20133 Milan (Italy)

    2011-12-15

    Biodegradable magnesium alloy stents (MAS) can provide a great benefit for diseased vessels and avoid the long-term incompatible interactions between vessels and permanent stent platforms. However, the existing MAS showed insufficient scaffolding to the target vessels due to short degradation time. In this study, a three dimensional finite element model combined with a degradable material model of AZ31 (Al 0.03, Zn 0.01, Mn 0.002 and Mg balance, mass percentage) was applied to three different MAS designs including an already implanted stent (Stent A), an optimized design (Stent B) and a patented stent design (Stent C). One ring of each design was implanted through a simulation in a vessel model then degraded with the changing interaction between outer stent surface and the vessel. Results showed that a proper stent design (Stent B) can lead to an increase of nearly 120% in half normalized recoil time of the vessel compared to the Stent A; moreover, the expectation that the MAS design, with more mass and optimized mechanical properties, can increase scaffolding time was verified numerically. The Stent C has more materials than Stent B; however, it only increased the half normalized recoil time of the vessel by nearly 50% compared to the Stent A because of much higher stress concentration than that of Stent B. The 3D model can provide a convenient design and testing tool for novel magnesium alloy stents.

  17. Aortoesophageal fistula as a complication of thoracic aorta aneurism stent grafting – a case report and literature review

    International Nuclear Information System (INIS)

    Endovascular stent grafting is performed in patients with aneurysms of aorta or other major vessels. The procedure is considered to be generally safe, with a low risk of complications, the most common of which include endoleaks, stenosis or thrombosis at the stagraft and itsmigration. Very rare complications include aortoesophageal and aortobronchial fistulas (0.5–1.7% cases). A 64-year-old patient was admitted to our hospital with suspected aortoesophageal fistula. Two years prior, the patient had undergone a stent graft repair of the thoracic aorta at the local vascular surgery clinic. Both laboratory results and CT angiography revealed aortoesophageal fistula, which was also detected in endoscopic examination. Despite intensive treatment and preparation for surgery, the patient died 6 days after admission. Aortoesophageal and aortobronchial fistulas are among the most dangerous and difficult-to-treat complications in the treatment of thoracic aortic aneurysms by endovascular stent-grafting. This clearly indicates that preventive care and regular medical examinations are important to prevent their occurrence

  18. Synthesis of Asymmetric Propanetriol Analogues

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    From natural tartaric acid, (R)-2-benzyloxy-3-(2-tetrahydropyranyloxy) propanol 3 was designed and synthesized, and (R)-2-benzyloxy-3-(4-methoxybenzyloxy) propanol 7 was prepared in a new method. They can be used as chiral synthons of lysophosphatidic acid and other compounds with asymmetric propanetriol backbone.

  19. Vertical asymmetric double quantum dots

    Science.gov (United States)

    Roßbach, R.; Reischle, M.; Beirne, G. J.; Schweizer, H.; Jetter, M.; Michler, P.

    2007-01-01

    Two layers of differently sized self-assembled InP-quantum dots (QDs) separated by a GaInP spacer layer with varying thickness were grown by metal organic vapor phase epitaxy (MOVPE). Photoluminescence measurements of the QD ensembles and of individual asymmetric double QDS show coupling due to the tunnelling of carriers.

  20. Asymmetrical Switch Costs in Children

    Science.gov (United States)

    Ellefson, Michelle R.; Shapiron, Laura R.; Chater, Nick

    2006-01-01

    Switching between tasks produces decreases in performance as compared to repeating the same task. Asymmetrical switch costs occur when switching between two tasks of unequal difficulty. This asymmetry occurs because the cost is greater when switching to the less difficult task than when switching to the more difficult task. Various theories about…