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Sample records for asymmetric vascular stent

  1. Stent-and-glue sutureless vascular anastomosis.

    Science.gov (United States)

    Khorgami, Zhamak; Shoar, Saeed; Aminian, Ali; Nasiri, Shirzad; Mahmoodzadeh, Habibollah

    2011-07-01

    Vascular anastomosis is commonly done by hand-sewn methods which not only are slow in pace, but also need experiences in surgeons' hands. As the old techniques are replaced by the new ones all the time, it is sensed that a new sutureless approach should be welcomed in the field of vascular anastomosis. Although lots of efforts have been done, such previous recommended techniques are associated with adverse consequences and here is where the need for new methods is still sensed. In this manuscript, we bring all the benefits from other methods together and conclude a novel one for end-to-end vascular anastomosis which uses biological glue as connecting material and also an absorbable stent to keep vessel patency while using balloon catheter and tacking suture.

  2. Drug release kinetics from a drug-eluting stent with asymmetrical coat

    DEFF Research Database (Denmark)

    Zhang, Haijun; Li, Xiaodong; Deng, Wei

    2017-01-01

    The aim of this study was to investigate the drug release profiles of biodegradable polymer sirolimus- or paclitaxel-eluting stents with asymmetrical coating (BPSES-A or BPPES-A) both in vitro and in vivo. In vitro, the drug release profile was characterized by measuring the drug concentration...... by HPLC over a time-course. In vivo, a porcine aorta stenting model was employed. The results showed that the drug release rates of BPSES-A and BPPES-A were slower, more stable and less burst releasing than those of conventionally coated stents (BPSES-C and BPPES-C respectively), both in vitro and in vivo...... demonstrated the effectiveness of both sirolimus and paclitaxel as stent coating agents, and revealed the favorable drug release kinetics and pharmacokinetics of asymmetrical coated stents compared with conventional coated stents....

  3. 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.

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

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    Bunck, Alexander C., E-mail: alexander.bunck@uk-koeln.de [Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster (Germany); Department of Radiology, University Hospital Cologne, Kerpener Strasse 62, 50937 Cologne (Germany); Jüttner, Alena, E-mail: alenajuettner@gmx.de [Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster (Germany); Kröger, Jan Robert, E-mail: jr.kroeger@uni-muenster.de [Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster (Germany); Burg, Matthias C., E-mail: m_burg03@uni-muenster.de [Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster (Germany); Kugel, Harald, E-mail: kugel@uni-muenster.de [Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster (Germany); Niederstadt, Thomas, E-mail: tnieders@uni-muenster.de [Department of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster (Germany); Tiemann, Klaus, E-mail: Klaus.Tiemann@ukmuenster.de [Department of Cardiology and Angiology, University Hospital Münster, Albert-Schweitzer-Campus 1, Building A1, 48149 Muenster (Germany); Schnackenburg, Bernhard, E-mail: bernhard.schnackenburg@philips.com [Philips Medical Systems DMC GmbH, Röntgenstraße 24, 22335 Hamburg (Germany); Crelier, Gerard R., E-mail: crelier@biomed.ee.ethz.ch [Institute for Biomedical Engineering, ETH and University of Zurich, ETZ F 95, Gloriastrasse 35, 8092 Zurich (Switzerland); and others

    2012-09-15

    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.

  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. 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.

  7. Investigation of the dynamic diameter deformation of vascular stents during fatigue testing with radial loading

    Directory of Open Access Journals (Sweden)

    Boeck Maria

    2015-09-01

    Full Text Available Endovascular stents are exposed to cyclic loads resulting from daily activity and pulsatile arterial blood pressure. DIN EN ISO 25539-2 and FDA guideline 1545 recommend durability testing, exposing stents to physiological cyclic loads for a 10 year equivalent. For accelerated testing, the simulated deformation has to be comparable to physiological in-vivo deformation. A new test setup is presented to determine diameter deformation of vascular stents during fatigue testing with radial loading.

  8. 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.

  9. Polyelectrolyte multilayers promote stent-mediated delivery of DNA to vascular tissue.

    Science.gov (United States)

    Saurer, Eric M; Jewell, Christopher M; Roenneburg, Drew A; Bechler, Shane L; Torrealba, Jose R; Hacker, Timothy A; Lynn, David M

    2013-05-13

    We report an approach to deliver DNA to vascular tissue in vivo using intravascular stents coated with degradable, DNA-containing polyelectrolyte multilayers (PEMs). Ionically cross-linked multilayers ∼120 nm thick were fabricated layer-by-layer on the surfaces of balloon-mounted stainless steel stents using plasmid DNA and a hydrolytically degradable poly(β-amino ester) (polymer 1). Characterization of stents coated using a fluorescently end-labeled analog of polymer 1 revealed film erosion to be uniform across the surfaces of the stents; differential stresses experienced upon balloon expansion did not lead to faster film erosion or dose dumping of DNA in areas near stent joints when stents were incubated in physiologically relevant media. The ability of film-coated stents to transfer DNA and transfect arterial tissue in vivo was then investigated in pigs and rabbits. Stents coated with films fabricated using fluorescently labeled DNA resulted in uniform transfer of DNA to sub-endothelial tissue in the arteries of pigs in patterns corresponding to the locations and geometries of stent struts. Stents coated with films fabricated using polymer 1 and plasmid DNA encoding EGFP resulted in expression of EGFP in the medial layers of stented tissue in both pigs and rabbits two days after implantation. The results of this study, combined with the modular and versatile nature of layer-by-layer assembly, provide a polymer-based platform that is well suited for fundamental studies of stent-mediated gene transfer. With further development, this approach could also prove useful for the design of nonviral, gene-based approaches for prevention of complications that arise from the implantation of stents and other implantable interventional devices.

  10. Mechanical stability of the diamond-like carbon film on nitinol vascular stents under cyclic loading

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyun-Jong [Department of Materials Science and Engineering, Seoul National University, Kwan-ak, Seoul 151-744 (Korea, Republic of); Advanced Functional Materials Research Center, Korea Institute of Science and Technology, Seung-buk, Seoul 136-791 (Korea, Republic of); Moon, Myoung-Woon [Future Fusion Technology Laboratory, Korea Institute of Science and Technology, Seung-buk, Seoul 136-791 (Korea, Republic of)], E-mail: mwmoon@kist.re.kr; Lee, Kwang-Ryeol [Future Fusion Technology Laboratory, Korea Institute of Science and Technology, Seung-buk, Seoul 136-791 (Korea, Republic of); Seok, Hyun-Kwang; Han, Seung-Hee [Advanced Functional Materials Research Center, Korea Institute of Science and Technology, Seung-buk, Seoul 136-791 (Korea, Republic of); Ryu, Jae-Woo; Shin, Kyong-Min [Taewoong Medical Inc. Ltd, Gimpo, Gyeonggi 415-873 (Korea, Republic of); Oh, Kyu Hwan [Department of Materials Science and Engineering, Seoul National University, Kwan-ak, Seoul 151-744 (Korea, Republic of)

    2008-12-01

    The mechanical stability of diamond-like carbon (DLC) films coated on nitinol vascular stents was investigated under cyclic loading condition by employing a stent crimping system. DLC films were coated on the vascular stent of a three dimensional structure by using a hybrid ion beam system with rotating jig. The cracking or delamination of the DLC coating occurred dominantly near the hinge connecting the V-shaped segments of the stent where the maximum strain was induced by a cyclic loading of contraction and extension. However the failures were significantly suppressed as the amorphous Si (a-Si) buffer layer thickness increased. Interfacial adhesion strength was estimated from the spalled crack size in the DLC coating for various values of the a-Si buffer layer thickness.

  11. 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.

  12. 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.

  13. Broncho-vascular fistulas from self-expanding metallic stents: A retrospective case review

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    Chirag Choudhary

    2013-01-01

    Full Text Available To highlight a potentially fatal complication of broncho-vascular fistula arising from the self expanding metallic stent (SEMS placement. We retrospectively analyzed five patients with benign and malignant airway diseases, who developed tracheo/broncho-vascular fistulas following SEMS placement in our tertiary care setting. All patients received either Wallstent or Ultraflex® stent (Boston Scientific, Natick, MA between 1999 and 2007. All patients had received adjunct therapy such as balloon bronchoplasty, laser therapy or electrocautery. Most patients presented with massive hemoptysis. A total of 483 SEMS were placed during this period. SEMS placement can be complicated by Broncho-vascular fistula formation. True incidence and precise time interval between the insertion of stent and onset of this complication is unknown. Additional therapeutic modalities to maintain stent patency may enhance the risk of fistula formation. SEMS should only be used in a select sub-group of patients, after exhaustive evaluation of other treatment options. These cases provide evidence that broncho-vascular fistulas can develop at any time following SEMS placement, suggesting the need for a more cautious approach, especially while using them for a long term management. In benign airway disease, the stent should be removed as soon as healing has taken place.

  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. Flow modification in canine intracranial aneurysm model by an asymmetric stent: studies using digital subtraction angiography (DSA) and image-based computational fluid dynamics (CFD) analyses

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    Hoi, Yiemeng; Ionita, Ciprian N.; Tranquebar, Rekha V.; Hoffmann, Kenneth R.; Woodward, Scott H.; Taulbee, Dale B.; Meng, Hui; Rudin, Stephen

    2006-03-01

    An asymmetric stent with low porosity patch across the intracranial aneurysm neck and high porosity elsewhere is designed to modify the flow to result in thrombogenesis and occlusion of the aneurysm and yet to reduce the possibility of also occluding adjacent perforator vessels. The purposes of this study are to evaluate the flow field induced by an asymmetric stent using both numerical and digital subtraction angiography (DSA) methods and to quantify the flow dynamics of an asymmetric stent in an in vivo aneurysm model. We created a vein-pouch aneurysm model on the canine carotid artery. An asymmetric stent was implanted at the aneurysm, with 25% porosity across the aneurysm neck and 80% porosity elsewhere. The aneurysm geometry, before and after stent implantation, was acquired using cone beam CT and reconstructed for computational fluid dynamics (CFD) analysis. Both steady-state and pulsatile flow conditions using the measured waveforms from the aneurysm model were studied. To reduce computational costs, we modeled the asymmetric stent effect by specifying a pressure drop over the layer across the aneurysm orifice where the low porosity patch was located. From the CFD results, we found the asymmetric stent reduced the inflow into the aneurysm by 51%, and appeared to create a stasis-like environment which favors thrombus formation. The DSA sequences also showed substantial flow reduction into the aneurysm. Asymmetric stents may be a viable image guided intervention for treating intracranial aneurysms with desired flow modification features.

  16. A novel polymer-free ciglitazone-coated vascular stent: in vivo and ex vivo analysis of stent endothelialization in a rabbit iliac artery model

    Science.gov (United States)

    Otto, Sylvia; Jaeger, Kristin; Kolodgie, Frank D.; Muehlstaedt, Diana; Franz, Marcus; Bischoff, Sabine; Schubert, Harald; Figulla, Hans R.; Virmani, Renu; Poerner, Tudor C.

    2016-01-01

    Aim Peroxisome proliferator-activated receptor-gamma (PPARg) agonists have known pleiotropic cardiovascular effects with favourable properties in vascular remodeling, and specifically in suppression of vascular smooth muscle cell proliferation. A novel vascular stent coating using the PPARg ligand ciglitazone (CCS) was investigated regarding its effects on endothelialization after 7 and 28 days. Methods Microporous bare metal stents (BMS) were coated with ciglitazone by ultrasonic flux with a load of 255 μg ciglitazone/stent. SixteenNew Zealand white rabbits, fed a with high cholesterol diet, underwent stent implantation in both iliac arteries. Everolimus-eluting stents (EES) and BMS were comparators. Histology (CD 31 immunostaining, confocal and scanning electron microscopy, morphometry) was performed after 7 and 28 days and by OCT (optical coherence tomography) in vivo after 28 days. Results Microscopy showed comparable results with near complete endothelialization in CCS and BMS (%CD31 above stent struts after 7 days: 67.92±36.35 vs. 84.48±23.86; p = 0.55; endothel % above stent struts: 77.22±27.9 vs. 83.89±27.91; p = 0.78). EES were less endothelialized with minimal fibrin deposition, not found in BMS and CCS (% CD 31 above struts after 28 days, BMS: 100.0±0.0 vs. EES: 95.9±3.57 vs. CCS: 100.0±0.0; p = 0.0292). OCT revealed no uncovered struts in all stents after 28 days. Conclusions Polymer-free coating with ciglitazone, a PPARg agonist is feasible and stable over time. Our data prove unimpaired endothelial coverage of a ciglitazone-coated vascular stent system by histology and OCT. Thus, this PPARg agonist coating deserves further investigation to evaluate its potency on local neointimal suppression. PMID:27613845

  17. Preparation and characterization of new nano-composite scaffolds loaded with vascular stents.

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    Xu, Hongzhen; Su, Jiansheng; Sun, Jun; Ren, Tianbin

    2012-01-01

    In this study, vascular stents were fabricated from poly (lactide-ɛ-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)/polycaprolactone/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.

  18. 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.

  19. 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.

  20. 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

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    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.

  1. Statistical characteristics of surface integrity by fiber laser cutting of Nitinol vascular stents

    Science.gov (United States)

    Fu, C. H.; Liu, J. F.; Guo, Andrew

    2015-10-01

    Nitinol alloys have been widely used in manufacturing of vascular stents due to the outstanding properties such as superelasticity, shape memory, and superior biocompatibility. Laser cutting is the dominant process for manufacturing Nitinol stents. Conventional laser cutting usually produces unsatisfactory surface integrity which has a significant detrimental impact on stent performance. Emerging as a competitive process, fiber laser with high beam quality is expected to produce much less thermal damage such as striation, dross, heat affected zone (HAZ), and recast layer. To understand the process capability of fiber laser cutting of Nitinol alloy, a design-of-experiment based laser cutting experiment was performed. The kerf geometry, roughness, topography, microstructure, and hardness were studied to better understand the nature of the HAZ and recast layer in fiber laser cutting. Moreover, effect size analysis was conducted to investigate the relationship between surface integrity and process parameters.

  2. 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.)

  3. Vascular stents with submicrometer-scale surface patterning realized via titanium deep reactive ion etching

    Science.gov (United States)

    Gott, Shannon C.; Jabola, Benjamin A.; Rao, Masaru P.

    2015-08-01

    Herein, we report progress towards realization of vascular stents that will eventually provide opportunity for evaluating cellular response to rationally-designed, submicrometer-scale surface patterning in physiologically-relevant contexts, i.e. those that provide exposure to the complex multicellular milieu, flow-induced shear, and tissue-device interactions present in vivo. Specifically, using our novel titanium deep reactive ion etching technique (Ti DRIE), we discuss recent advances that have enabled: (a) fabrication of precisely-defined, grating-based surface patterns on planar Ti foils with minimum feature sizes as small as 0.15 μm (b) creation of cylindrical stents from micromachined planar Ti foils; and (c) integration of these processes to produce the first submicrometer-scale surface-patterned Ti stents that are compatible with conventional balloon catheter deployment techniques. We also discuss results from elastoplastic finite element simulations and preliminary mechanical testing of these devices to assess their mechanical performance. These efforts represent key steps towards our long-term goal of developing a new paradigm in stenting, where rationally-designed surface patterning provides a physical means for facilitating healing, and thus, improving outcomes in vascular intervention applications.

  4. Numerical investigations of the mechanical properties of a braided non-vascular stent design using finite element method.

    Science.gov (United States)

    Ni, Xiao-Yu; Pan, Chang-Wang; Gangadhara Prusty, B

    2015-08-01

    This paper discusses various issues relating to the mechanical properties of a braided non-vascular stent made of a Ni-Ti alloy. The design of the stent is a major factor which determines its reliability after implantation into a stenosed non-vascular cavity. This paper presents the effect of the main structural parameters on the mechanical properties of braided stents. A parametric analysis of a commercial stent model is developed using the commercial finite element code ANSYS. As a consequence of the analytical results that the pitch of wire has a greater effect than other structural parameters, a new design of a variable pitch stent is presented to improve mechanical properties of these braided stents. The effect of structural parameters on mechanical properties is compared for both stent models: constant and variable pitches. When the pitches of the left and right quarters of the stent are 50% larger and 100% larger than that of the central portion, respectively, the radial stiffness in the central portion increases by 10% and 38.8%, while the radial stiffness at the end portions decreases by 128% and 164.7%, the axial elongation by 25.6% and 56.6% and the bending deflection by 3.96% and 10.15%. It has been demonstrated by finite element analysis that the variable pitch stent can better meet the clinical requirements.

  5. 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.

  6. 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.

  7. IVUS-Guided Implantation of Bioresorbable Vascular Scaffolds for Very Late Paclitaxel Stent Thrombosis

    Science.gov (United States)

    Lin, Zhe-Zhong; Chang, Wei-Ting; Chiang, Chun-Yen; Chen, Zhih-Cherng; Ku, Po-Ming

    2017-01-01

    Bioresorbable vascular scaffold (BVS) implantation has been shown to be safe in patients with stable coronary disease, and effective against the thrombotic lesion and the in-stent restenosis (ISR) of the drug-eluting stent (DES). BVSs have the advantages of a snow racket concept, positive vessel remodeling, and better conformability compared with DES in acute coronary syndrome (ACS). We report on a young patient with ST-elevation myocardial infarction (STEMI) who presented to our emergency department arising from very late stent thrombosis (VLST) of a 2.5 × 28 mm paclitaxel-eluting stent (Coroflex® Please) three years after its implantation. After the patient was treated with balloon dilation, intravascular ultrasound (IVUS) revealed a short segment of a guide wire outside the DES mesh. Two BVSs were implanted to prevent a DES recoil. Post-scaffold-implantation IVUS showed adequately expanded strut of BVSs. Six months later, optical coherence tomography (OCT) revealed that some segments of the scaffold had been absorbed and that there was no in-scaffold restenosis. The patient had not complained about angina during the out-patient clinic follow-up. This is the first report of successful BVS implantation for a STEMI patient attributable to DES VLST. PMID:28115812

  8. 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.

  9. 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.

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

    DEFF Research Database (Denmark)

    Wu, Xue; Yin, Tieying; Tian, Jie;

    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......-coated stents, the time of cells adhesion was longer and earlier present in the anti-CD133 antibody-coated stents and anti-CD133 antibody-coated stents have superiority in re-endothelialization and inhibition of ISR. In conclusion, this study demonstrated that anti-CD133 antibody as a stent coating...... for capturing EPCs is better than anti-CD34 antibody in promoting endothelialization and reducing ISR....

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Improved anticoagulation management after Palmaz Schatz coronary stent implantation by sealing the arterial puncture site with a vascular hemostasis device.

    Science.gov (United States)

    Kiemeneij, F; Laarman, G J

    1993-12-01

    Sealing the arterial puncture site with a vascular hemostasis device has the potential to maintain optimal anticoagulation after stent implantation. The level of heparinization during the first 3 days after successful stent implantation was retrospectively compared between 2 groups of medically treated patients with (group A; n = 18) and without (group B; n = 17) a Vasoseal after sheath removal. The number of APTTs sampled in group A and B was 233 and 168, respectively. Respective mean values of APTT (seconds) in group A and B were 180 +/- 79 and 172 +/- 91 at day 1 (p = NS), 132 +/- 43 and 125 +/- 61 at day 2 (p = NS) and 123 +/- 36 and 116 +/- 48 at day 3 (p = NS). More APTTs were suboptimal (< 80 secs) in group B (34/168; 20%) compared to group A (17/233; 7%) [p < 0.001]. More patients in group B compared to group A had 1 or more (14/17; 82% vs. 8/18; 44%; p = 0.04), 2 or more (10/17; 59% versus 3/18; 17%; p = 0.02) and 3 or more (8/17; 47% vs. 2/18; 11%; p = 0.03) suboptimal APTTs. Bleeding complications were seen in 4 patients without and in 3 patients with a Vasoseal. Thus application of a vascular hemostasis device results in a less variable anticoagulation after coronary stenting, but it does not abolish entry site-related bleeding complications.

  16. Biodegradable polymeric stents for vascular application in a porcine carotid artery model: English version.

    Science.gov (United States)

    Kischkel, S; Grabow, N; Püschel, A; Erdle, B; Kabelitz, M; Martin, D P; Williams, S F; Bombor, I; Sternberg, K; Schmitz, K-P; Schareck, W; Bünger, C M

    Over the past years the development of biodegradable polymeric stents has made great progress; nevertheless, essential problems must still be solved. Modifications in design and chemical composition should optimize the quality of biodegradable stents and remove the weaknesses. New biodegradable poly-L-lactide/poly-4-hydroxybutyrate (PLLA/P4HB) stents and permanent 316L stents were implantedendovascularly into both common carotid arteries of 10 domestic pigs. At 4 weeks following implantation, computed tomography (CT) angiography was carried out to identify the distal degree of stenosis. The PLLA/P4HB group showed a considerably lower distal degree of stenosis by additional oral application of atorvastatin (mean 39.81 ± 8.57 %) compared to the untreated PLLA/P4HB group without atorvastatin (mean 52.05 ± 5.80 %). The 316L stents showed no differences in the degree of distal stenosis between the group treated with atorvastatin (mean 44.21 ± 2.34 %) and the untreated group (mean 35.65 ± 3.72 %). Biodegradable PLLA/P4HB stents generally represent a promising approach to resolving the existing problems in the use of permanent stents. Restitutio ad integrum is only achievable if a stent is completely degraded.

  17. Coronary Artery Stent Evaluation Using a Vascular Model at 64-Detector Row CT: Comparison between Prospective and Retrospective ECG-Gated Axial Scans

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Shigeru; Furui, Shigeru; Kaminaga, Tatsuro; Miyazawa, Akiyoshi; Ueno, Yasunari; Konno, Kumiko [Teikyo University School of Medicine, Tokyo (Japan); Kuwahara, Sadatoshi; Mehta, Dhruv [Philips Electronics Japan, Ltd. Medical Systems, Tokyo (Japan)

    2009-06-15

    We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans. As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube. Both patent and stenotic models of coronary artery were made by instillating different attenuation (396 vs. 79 Hounsfield unit [HU]) of contrast medium within the tube in tube model. The models were scanned with two types of scan methods with a simulated ECG of 60 beats per minute and using display field of views (FOVs) of 9 and 18 cm. We evaluated the in-stent stenosis visually, and we measured the attenuation values and the diameter of the patent stent lumen. The visualization of the stent lumen of the vascular models was improved with using the prospective ECG-gated axial scans and a 9-cm FOV. The inner diameters of the vascular models were underestimated with mean measurement errors of -1.10 to -1.36 mm. The measurement errors were smaller with using the prospective ECG-gated axial scans (Bx-Velocity and Express2, p < 0.0001; Micro Driver, p = 0.0004) and a 9-cm FOV (all stents: p < 0.0001), as compared with the other conditions, respectively. The luminal attenuation value was overestimated in each condition. For the luminal attenuation measurement, the use of prospective ECG-gated axial scans provided less measurement error compared with the retrospective ECG-gated helical scans (all stents: p < 0.0001), and the use of a 9-cm FOV tended to decrease the measurement error. The visualization of coronary stents is improved by the use of prospective ECG-gated axial scans and using a small FOV with reduced blooming artifacts and increased spatial resolution.

  18. 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.

  19. Repair of Chronic Aneurysmal Aortic Dissection Using a Stent Graft and an Amplatzer(®) Vascular Plug: A Case Study.

    Science.gov (United States)

    Kanaoka, Yuji; Ohki, Takao; Ozawa, Hirotsugu

    2017-02-01

    We report a case in which a stent graft and an Amplatzer(®) vascular plug (AVP) were effective for the treatment of chronic aneurysmal aortic dissection. The patient was a 52-year-old man. At 45 years of age, he developed acute aortic dissection, for which he underwent surgery 4 times with prosthetic graft replacement in the abdominal aorta, descending thoracic, ascending aorta (without neck branch reconstruction), and thoracoabdominal aorta with the reconstruction of the celiac, superior mesenteric, and bilateral renal arteries. At the time of thoracoabdominal aortic surgery, strong adhesion was evident, particularly in the thoracoabdominal area. The adhesion was dissected in a part of the chest, and prosthetic graft replacement was performed the following day. Subsequently, the dissection of the residual distal aortic arch enlarged, and the patient was examined at our hospital. Computed tomography (CT) revealed a small intimal tear at the site of anastomosis distal to the graft in the ascending aorta and a large intimal tear in the descending thoracic aorta with a maximum diameter of 67 mm. Furthermore, open repair by prosthetic graft replacement seemed difficult; therefore, treatment with stent grafting was considered. Because the prosthetic graft in the abdomen was extremely tortuous, stent-graft insertion via the femoral artery seemed to be impossible. The planned treatment involved the placement of a thoracic stent graft using the chimney technique which included reconstruction of the brachiocephalic artery and left common carotid arteries using chimney stent graft and coverage of the left subclavian artery. The thoracic stent graft was planned to be inserted via the abdominal prosthetic graft site because the abdominal prosthetic graft was crooked and was located close to the body surface. However, a small intimal tear distal to the graft in the ascending aorta which had not been revealed by intraoperative aortography was detected by the selective

  20. Effect of Solitaire AB stent thrombectomy on vascular endothelial function and inflammatory cytokines in patients with progressive cerebral infarction

    Institute of Scientific and Technical Information of China (English)

    Zhi-Bao Wu; Xue-Juan Han; Zi-Hao Zhang; Wen-Liang Zhang; Liang Liu

    2016-01-01

    Objective:To observe the effect of Solitaire AB stent thrombectomy on the vascular endothelial function and inflammatory cytokines in patients with progressive cerebral infarction.Methods:A total of 58 patients with progressive cerebral infarction who were admitted in our hospital were included in the study and divided into the observation group and the control group according to different treatment protocols with 29 cases in each group. The patients in the control group were given the conservation treatment. On this basis, the patients in the observation group were given Solitaire AB stent thrombectomy. The changes of vascular endothelial function and inflammatory cytokines before and after treatment in the two groups were compared.Results:ET-1 after treatment in the two groups was significantly reduced, while NO and CGRP were significantly elevated when compared with before treatment (P<0.05). ET-1 after treatment in the observation group was significantly lower than that in the control group (P<0.05), while NO and CGRP were significantly higher than those in the control group (P<0.05). S100β protein, IL-6, TNF-α, hs-CRP, and MMP-9 levels after treatment in the two groups were significantly reduced when compared with before treatment (P<0.05). The above indicators after treatment in the observation group were significantly lower than those in the control group (P<0.05). MCA and ACA blood flow velocity after treatment in the two groups were significantly elevated when compared with before treatment (P<0.05). MCA and ACA blood flow velocity after treatment in the observation group were significantly higher than those in the control group (P<0.05).Conclusions:Solitaire AB stent thrombectomy can effectively reduce the inflammatory reaction in patients with progressive cerebral infarction, and improve the vascular endothelial function and blood supply for brain tissues.

  1. Vascular Biocompatibility of a Triple Layered Self Expanding Stent-Graft in a Dog Mode

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Jae Ik; Won, Je Hwan; Jang, Eun Ho; Lee, Sung Yeong; Ko, Kwang Tae [Dept. of Radiology, Ajou University School of Medicine, Suwon (Korea, Republic of); Jin, Bo Hwan [Medical Science Research Center, Ajou University School of Medicine, Suwon (Korea, Republic of); Lee, June Woo [Dept. of Radiology, Busan National University College of Medicine, Busan (Korea, Republic of)

    2012-02-15

    To evaluate performance and biocompatibility of a newly designed self-expanding stent graft, which consisted of two nitinol stents and an intervening expanded polytetrafluoroethylene membrane in a dog artery model. Twelve stent grafts were placed in the aorta of 6 dogs (beagle, mean body weight 11 kg) for 4 weeks (n = 4) and 12 weeks (n = 8). Luminal diameters were measured for each segment (the proximal bare, the middle graft, the distal bare) by angiographies after implantation and follow up periods. Percent luminal stenosis based on angiographies, histomorphometric, histologic, and scanning electron microscopic analyses of each segments were performed. Blood flow through the stent grafts was good after implantation and during the follow up period, without thrombotic occlusion or stent graft migration. The mean percent luminal stenosis of the proximal bare, the middle grafted and the distal bare segments after 12 weeks were 13.5%, 3.9%, 9.6% retrospectively. The mean neointimal areas of the middle grafted segment were 4.39 mm{sup 2} (4 week) and 4.92 mm{sup 2} (12 week). Mature endothelialization was evident in over 70% of the area of the stented artery after 4 weeks and in over 90% after 12 weeks. The stent graft was well placed in the attempted area without migration. During the 12-week-follow up period, it showed a good patency without thrombotic occlusion or significant in-stent luminal stenosis. Endothelialization was rapid and nearly complete. Neointima was thin and smooth on the middle graft segment and thicker and irregular on the bare segments.

  2. Bioresorbable vascular scaffold (BVS) for in-stent chronic total occlusion: Antegrade recanalization and IVUS-guided BVS implantation by radial access

    Energy Technology Data Exchange (ETDEWEB)

    Medda, Massimo [Interventional Cardiology Unit, Istituto Clinico Sant' Ambrogio, Milano (Italy); Casilli, Francesco, E-mail: frcasill@tin.it [Interventional Cardiology Unit, Istituto Clinico Sant' Ambrogio, Milano (Italy); Bande, Marta [Interventional Cardiology Unit, Istituto Clinico Sant' Ambrogio, Milano (Italy); Latini, Maria Giulia [Cardiologia Interventistica, IRCCS Policlinico San Donato, San Donato Milanese, Milano (Italy); Ghommidh, Mehdi [Interventional Cardiology Unit, Istituto Clinico Sant' Ambrogio, Milano (Italy); Del Furia, Francesca [Unità Operativa di Cardiologia, Azienda Ospedaliera di Melegnano, Milano (Italy); Inglese, Luigi [Interventistica Cardiovascolare, Gruppo Sanitario Policlinico di Monza, Milano (Italy)

    2016-01-15

    The completely absorbable stents represent one of the latest innovations in the field of interventional cardiology, prospecting the possibility of “vascular repair”. In the published trials (ABSORB Cohort A and B, ABSORB EXTEND, and ABSORB II, III and IV) chronic total occlusions (CTOs) were considered an exclusion criteria. More recently the CTO-ABSORB pilot study demonstrated the safety and feasibility of bioresorbable vascular scaffold (BVS) use in case of CTO recanalization. We present the first case, to our knowledge, of in-stent occlusion successfully treated with an everolimus-eluting BVS and discuss its potential advantages in such kind of lesions.

  3. Subclavian artery pseudoaneurysm complicating central venous catheterization: endovascular treatment with Amplatzer Vascular Plug 4 and covered stent.

    Science.gov (United States)

    Rossi, Umberto G; Petrocelli, Francesco; Ferro, Carlo

    2013-12-01

    Central venous catheterization is a routine vascular access procedure; however, it may be associated with life-threatening complications such as arterial puncture, leading to pseudoaneurysm formation. We report a case of a 41-year-old female that developed an iatrogenic left subclavian pseudoaneurysm complicating the attempt of left internal jugular vein cannulation for temporary hemodialysis therapy. The patient underwent urgent endovascular treatment with deployment of covered stent into the left subclavian artery (SCA) after embolization of the origin of the left internal mammary artery with Amplatzer Vascular Plug 4. The patient's recovery was unremarkable. Follow-up till 24 months reveals total exclusion of the pseudoaneurysm of the left SCA with patency of the distal branches.

  4. 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.

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

    Science.gov (United States)

    Li, Xiu-Mei; Li, Hui-Zhe; Wang, Shao-Ping; Huang, Hsun-Miao; Huang, Her-Hsiung; Ai, Hong-Jun; Xu, Jian

    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.

  6. 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.

  7. 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

  8. 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.

  9. Research on a Zn-Cu alloy as a biodegradable material for potential vascular stents application.

    Science.gov (United States)

    Niu, Jialin; Tang, Zibo; Huang, Hua; Pei, Jia; Zhang, Hua; Yuan, Guangyin; Ding, Wenjiang

    2016-12-01

    Zn-based alloys have been viewed as new potential materials for biodegradable implants, such as cardiovascular stents, mainly in consideration of their lower corrosion rate when compared with that of Mg alloys. In this study we developed a new Zinc-4wt.%Copper (Zn-4Cu) alloy as a biodegradable material. Hot extrusion was applied to Zn-4Cu to refine the microstructure and consequently improve its mechanical properties and corrosion resistance. After extrusion, dendritic CuZn5 phases were broken and distributed along the extrusion direction. The grains were refined obviously due to dynamical recrystallization. The yield strength (YS), ultimate tensile strength (UTS) and elongation of the as-extruded alloy are 250±10MPa, 270±10MPa and 51±2%, respectively. The corrosion rate of the as-extruded alloy in Hank's solution is about 9.41(±1.34)μmyear(-1). In vitro evaluation shows that Zn-4Cu presents acceptable toxicity to human endothelial cells, and could effectively inhibit bacteria adhesion and biofilm formation. The present study indicates that the as-extruded Zn-4Cu alloy exhibits excellent strength and ductility, uniform and slow degradation, good biocompatibility and significant antibacterial effect, which make it an excellent candidate material for biodegradable implants, especially for cardiovascular stents application.

  10. 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.

  11. 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.

  12. 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.

  13. Endovascular Gene Delivery from a Stent Platform: Gene- Eluting Stents.

    Science.gov (United States)

    Fishbein, Ilia; Chorny, Michael; Adamo, Richard F; Forbes, Scott P; Corrales, Ricardo A; Alferiev, Ivan S; Levy, Robert J

    A synergistic impact of research in the fields of post-angioplasty restenosis, drug-eluting stents and vascular gene therapy over the past 15 years has shaped the concept of gene-eluting stents. Gene-eluting stents hold promise of overcoming some biological and technical problems inherent to drug-eluting stent technology. As the field of gene-eluting stents matures it becomes evident that all three main design modules of a gene-eluting stent: a therapeutic transgene, a vector and a delivery system are equally important for accomplishing sustained inhibition of neointimal formation in arteries treated with gene delivery stents. This review summarizes prior work on stent-based gene delivery and discusses the main optimization strategies required to move the field of gene-eluting stents to clinical translation.

  14. 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...

  15. 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.

  16. Angioplasty and Vascular Stenting

    Science.gov (United States)

    ... aorta and its branches) due to atherosclerosis , or hardening of the arteries, a gradual process in which ... medications. These may be taken with sips of water on the morning of your procedure. Other than ...

  17. 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)....

  18. Mechanical Interaction of an Expanding Coiled Stent with a Plaque-Containing Arterial Wall: A Finite Element Analysis.

    Science.gov (United States)

    Welch, Tré R; Eberhart, Robert C; Banerjee, Subhash; Chuong, Cheng-Jen

    2016-03-01

    Wall injury is observed during stent expansion within atherosclerotic arteries, related in part to stimulation of the inflammatory process. Wall stress and strain induced by stent expansion can be closely examined by finite element analysis (FEA), thus shedding light on procedure-induced sources of inflammation. The purpose of this work was to use FEA to examine the interaction of a coiled polymer stent with a plaque-containing arterial wall during stent expansion. An asymmetric fibrotic plaque-containing arterial wall model was created from intravascular ultrasound (IVUS) images of a diseased artery. A 3D model for a coil stent at unexpanded state was generated in SolidWorks. They were imported into ANSYS for FEA of combined stent expansion and fibrotic plaque-distortion. We simulated the stent expansion in the plaqued lumen by increasing balloon pressure from 0 to 12 atm in 1 atm step. At increasing pressure, we examined how the expanding stent exerts forces on the fibrotic plaque and vascular wall components, and how the latter collectively resist and balance the expansive forces from the stent. Results show the expanding coiled stent creates high stresses within the plaque and the surrounding fibrotic capsule. Lower stresses were observed in adjacent medial and adventitial layers. High principal strains were observed in plaque and fibrotic capsule. The results suggest fibrotic capsule rupture might occur at localized regions. The FEA/IVUS method can be adapted for routine examination of the effects of the expansion of selected furled stents against IVUS-reconstructed diseased vessels, to improve stent deployment practices.

  19. 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.

  20. 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...... with delayed arterial healing and impaired stent-related outcomes. The purpose of the present study is to compare directly the arterial healing response, angiographic efficacy and clinical outcomes between the Absorb BVS and metallic EES. Methods and results: A total of 191 patients with acute STEMI were...... randomly allocated to treatment with the Absorb BVS or a metallic EES 1:1. The primary endpoint is the neointimal healing (NIH) score, which is calculated based on a score taking into consideration the presence of uncovered and malapposed stent struts, intraluminal filling defects and excessive neointimal...

  1. 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...

  2. Rho/ROCK signal cascade mediates asymmetric dimethylarginine-induced vascular smooth muscle cells migration and phenotype change.

    Science.gov (United States)

    Zhou, Yi-ming; Lan, Xi; Guo, Han-bin; Zhang, Yan; Ma, Li; Cao, Jian-biao

    2014-01-01

    Asymmetric dimethylarginine (ADMA) induces vascular smooth muscle cells (VSMCs) migration. VSMC phenotype change is a prerequisite of migration. RhoA and Rho-kinase (ROCK) mediate migration of VSMCs. We hypothesize that ADMA induces VSMC migration via the activation of Rho/ROCK signal pathway and due to VSMCs phenotype change. ADMA activates Rho/ROCK signal pathway that interpreted by the elevation of RhoA activity and phosphorylation level of a ROCK substrate. Pretreatment with ROCK inhibitor, Y27632 completely reverses the induction of ADMA on ROCK and in turn inhibits ADMA-induced VSMCs migration. When the Rho/ROCK signal pathway has been blocked by pretreatment with Y27632, the induction of ERK signal pathway by ADMA is completely abrogated. Elimination of ADMA via overexpression of dimethylarginine dimethylaminohydrolase 2 (DDAH2) and L-arginine both blocks the effects of ADMA on the activation of Rho/ROCK and extra cellular signal-regulated kinase (ERK) in VSMCs. The expression of differentiated phenotype relative proteins was reduced and the actin cytoskeleton was disassembled by ADMA, which were blocked by Y27632, further interpreting that ADMA inducing VSMCs migration via Rho/ROCK signal pathway is due to its effect on the VSMCs phenotype change. Our present study may help to provide novel insights into the therapy and prevention of atherosclerosis.

  3. The Control of Drug Release and Vascular Endothelialization after Hyaluronic Acid-Coated Paclitaxel Multi-Layer Coating Stent Implantation in Porcine Coronary Restenosis Model

    Science.gov (United States)

    Bae, In-Ho; Jeong, Myung Ho; Park, Yong Hwan; Lim, Kyung Seob; Park, Dae Sung; Shim, Jae Won; Kim, Jung Ha; Ahn, Youngkeun; Hong, Young Joon; Sim, Doo Sun

    2017-01-01

    Background and Objectives Hyaluronic acid (HA) is highly biocompatible with cells and the extracellular matrix. In contrast to degradation products of a synthetic polymer, degradation products of HA do not acidify the local environment. The aim of this study was to fabricate an HA-coated paclitaxel (PTX)-eluting stent via simple ionic interactions and to evaluate its effects in vitro and in vivo. Materials and Methods HA and catechol were conjugated by means of an activation agent, and then the stent was immersed in this solution (resulting in a HA-coated stent). After that, PTX was immobilized on the HA-coated stent (resulting in a hyaluronic acid-coated paclitaxel-eluting stent [H-PTX stent]). Study groups were divided into 4 groups: bare metal stent (BMS), HA, H-PTX, and poly (L-lactide)-coated paclitaxel-eluting stent (P-PTX). Stents were randomly implanted in a porcine coronary artery. After 4 weeks, vessels surrounding the stents were isolated and subjected to various analyses. Results Smoothness of the surface was maintained after expansion of the stent. In contrast to a previous study on a PTX-eluting stent, in this study, the PTX was effectively released up to 14 days (a half amount of PTX in 4 days). The proliferation of smooth muscle cells was successfully inhibited (by 80.5±12.11% at 7 days of culture as compared to the control) by PTX released from the stent. Animal experiments showed that the H-PTX stent does not induce an obvious inflammatory response. Nevertheless, restenosis was clearly decreased in the H-PTX stent group (9.8±3.25%) compared to the bare-metal stent group (29.7±8.11%). Conclusion A stent was stably coated with PTX via simple ionic interactions with HA. Restenosis was decreased in the H-PTX group. These results suggest that HA, a natural polymer, is suitable for fabrication of drug-eluting stents (without inflammation) as an alternative to a synthetic polymer.

  4. Outcome of everolimus eluting bioabsorbable vascular scaffold (BVS) compared to non BVS drug eluting stent in the management of ST-segment elevation myocardial infarction (STEMI) — A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Chakraborty, Rabin; Patra, Soumya, E-mail: dr_soumyapatra@rediffmail.com; Banerjee, Suvro; Pande, Arindam; Khan, Aftab; Mandol, Prakash Chandra; Ghosh, Debashish; De, Swapan Kumar; Das, Sankha Subhro; Nag, Raja

    2016-04-15

    Background: The safety and efficacy of everolimus eluting bioabsorbable vascular scaffold (BVS) in the management of “ST” segment elevation myocardial infarction (STEMI) are yet to be established. Aims: To evaluate immediate and short term safety and efficacy of the everolimus-eluting ABSORB BVS compared with non BVS drug eluting stent (DES) in patients with STEMI. Methods: From December 2013 to December 2014, 220 patients with STEMI were included in this study. Among them, 35 patients treated with BVS were compared with a control group composed of 180 patients who underwent non BVS DES implantation in the same time period. The incidence of major adverse cardiac events (MACE: stent thrombosis: death, non-fatal myocardial infarction, or target vessel/lesion revascularization) before discharge and up to six months was evaluated. Results: 1 vessel disease was more frequent whereas, 2 and 3 vessel disease was less frequent in BVS group. Procedural characteristics were also similar between groups, except for the use of post dilation (p = 0.04). Procedural success, in-hospital, and up to six-month MACE rates were similar between both groups. Definite or probable stent thrombosis did not occur (according to the ARC criteria) in BVS patients, though two patients during the index admission and another two patients in the first month after DES implantation had stent thrombosis. Conclusion: The use of the ABSORB BVS for STEMI is feasible and associated with good procedural safety, and angiographic success rate.

  5. 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

  6. Refining stent technologies for femoral interventions.

    Science.gov (United States)

    Bosiers, M; Deloose, K; Callaert, J; Maene, L; Keirse, K; Verbist, J; Peeters, P

    2012-08-01

    Stents were created as a mechanical scaffold to prevent vessel recoil and luminal renarrowing after percutaneous transluminal angioplasty (PTA). In femoropopliteal arteries, indication for stent implantation remains a topic much debated on, especially in long lesion configurations. Ever since the first stents were introduced on the market, in-stent restenosis (ISR) has been an important issue. The evolution in stent design has known a major progression in the last decades from the first generation of stents, plagued with high fracture rates and low primary patency rates, to the design of newer stents to tackle these outcomes. More flexible and longer stents decreased the high fracture rates and drug-eluting stents offered a solution to the restenosis rates by local drug application. The difficult recrossibility of the lesion because of the presence of a permanent vascular scaffold is an obstacle that the drug-coated balloon (DCB) overcomes. Future perspectives in the treatment of femoropopliteal lesions are found in the bioresorbable stent implantation. The bioresorbable stent combines the advantages of a drug-eluting scaffolding stent without the remainder of a foreign object in the long-term. Further investigations in this area will eventually evolve in the creation of a superior endovascular treatment modality with high long-term patency rates and minimal detriments.

  7. 肝内门腔分流术支架与血管支架组织成分的对比研究%Experimental comparison study of the tissue characteristics in transjugular intrahepalic portosystemic shunt and vascular stent

    Institute of Scientific and Technical Information of China (English)

    卢勤; 魏晓莹; 滕皋军; 安艳丽; 邓钢; 方文; 朱光宇; 牛焕章; 余辉; 李国昭; 王甄

    2009-01-01

    Objective To investigate the tissue characteristics within vascular stent and transjugular intrahepatic portosystemic shunt(TIPS)on swine and to provide more information for the understanding and prevention of vascular stent and TIPS restenosis.Methods Animal models for TIPS were built in 6 swine and vascular stents were implanted in iliac veins simultaneouly.14-28 days after the operation.the 6 swine were killed to remove the TIPS and vascular stent and the pathological examinations were performed on the tissues within the shunt and stent.The similarities and difierences of the tissues within the shunt and stent were analvzed with Kruskal Wallis test. Results Restenosis of TIPS occurred in 4 models and complete occlusion were seen in 2,while all vascular stents were patent and coated with a thin layer of intimal tissueElectron micmscopic results showed that the tissues in restenotic TIPS were loose and with more extra matrix and fibers.and less smooth muscle,fibroblastic and myofibroblastic cells with different and irregular shape and rich secretory granules.The tissues in patent,TIPS contained more extra fibers,smooth muscle and fibmblastic cells with normal organdie.The intimal tissues in vascular stent contained more fibers and fibroblasts cells.less smooth muscle cells.On immunohistoehemical staining,the tissues in restenotlc and Datent TIPS as well as the intimal tissues in vascular stent had strong positive expression for anti-SMCactin-α.the expression were gradually weakened for PCNA,the intimal tissues in vascular stent had a strong positive expression for vimentin,while the expression of the tissues in restenotic and patent TIPS were weakened gradually.For myoglobulin,the tissues in restenotic TIPS had weakly positive expression,the expression in patent TIPS and vascular stent were almost negative. Western blot results for TGF-β showed that the absorbance ratios of the intima tissues in vascular stent,normal vascular tissues,normal liver tissues

  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. 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....

  10. 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.

  11. 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

  12. 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

  13. 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%,

  14. Intracranial Vascular Treatments

    Science.gov (United States)

    ... full size with caption Related Articles and Media Gamma Knife Linear Accelerator Catheter Embolization Angioplasty and Vascular Stenting Proton Therapy Radiation Dose in X-Ray and CT Exams Stereotactic ...

  15. 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.

  16. Increase of ADAM10 level in coronary artery in-stent restenosis segments in diabetic minipigs: high ADAM10 expression promoting growth and migration in human vascular smooth muscle cells via Notch 1 and 3.

    Directory of Open Access Journals (Sweden)

    Ke Yang

    Full Text Available BACKGROUND: This study aimed to identify major proteins in the pathogenesis of coronary artery in-stent restenosis (ISR in diabetic minipigs with sirolimus-eluting stenting, and to investigate the roles of key candidate molecules, particularly ADAM10, in human arterial smooth muscle cells (HASMCs. METHODS AND RESULTS: The stents were implanted in the coronary arteries of 15 diabetic and 26 non-diabetic minipigs, and angiography was repeated at six months. The intima of one vascular segment with significant ISR and one with non-ISR in diabetic minipigs were isolated and cultured in conditioned medium (CM. The CM was analyzed by LC-MS/MS to uncover proteins whose levels were significantly increased (≥ 1.5-fold in ISR than in non-ISR tissues. After literature searching, we focused on the identified proteins, whose biological functions were most potentially related to ISR pathophysiology. Among them, ADAM10 was significantly increased in diabetic and non-diabetic ISR tissues as compared with non-ISR controls. In cell experiments, retrovirus-mediated overexpression of ADAM10 promoted growth and migration of HASMCs. The effects of ADAM10 were more remarkable in high-glucose culture than in low-glucose culture. Using shRNA and an inhibitor of γ-secretase (GSI, we found that the influences of ADAM10 were in part mediated by Notch1 and notch 3 pathway, which up-regulated Notch downstream genes and enhanced nuclear translocation of the small intracellular component of Notch1 and Notch3. CONCLUSIONS: This study has identified significantly increased expression of ADAM10 in the ISR versus non-ISR segment in diabetic minipigs and implicates ADAM10 in the enhanced neointimal formation observed in diabetes after vascular injury.

  17. Early vascular healing with rapid breakdown biodegradable polymer sirolimus-eluting versus durable polymer everolimus-eluting stents assessed by optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Tomohisa, E-mail: tomohisa@dhm.mhn.de [Deutsches Herzzentrum, Technische Universität, München (Germany); Byrne, Robert A. [Deutsches Herzzentrum, Technische Universität, München (Germany); Schuster, Tibor [Institut für Medizinische Statistik und Epidemiologie, München (Germany); Cuni, Rezarta [Deutsches Herzzentrum, Technische Universität, München (Germany); Kitabata, Hironori [Wakayama Medical University, Wakayama (Japan); Tiroch, Klaus [Deutsches Herzzentrum, Technische Universität, München (Germany); Dirninger, Alfred; Gratze, Franz; Kaspar, Klaus; Zenker, Gerald [Landeskrankenhaus Bruck/Mur (Austria); Joner, Michael; Schömig, Albert; Kastrati, Adnan [Deutsches Herzzentrum, Technische Universität, München (Germany)

    2013-03-15

    Background: Differences in early arterial healing patterns after stent implantation between biodegradable and durable polymer based new generation drug-eluting stents are not well understood. The aim of this study was to compare the healing patterns of a novel rapid breakdown (≤ 8 weeks) biodegradable polymer sirolimus-eluting stent (BP-SES) with a durable polymer everolimus-eluting stent (EES) using intravascular optical coherence tomography (OCT) at 4 months. Methods: A total of 20 patients were randomly assigned to stenting with BP-SES (n = 11) or EES (n = 9). Overall intravascular imaging was available for 15 (75%) patients. The primary endpoint was the difference in rate of uncovered struts between BP-SES and EES. To account for strut-level clustering, the results in both treatment groups were compared using a generalized linear mixed model approach. Results: Regarding the primary endpoint, BP-SES as compared to EES showed similar rates of uncovered struts (37 [6.8%] versus 167 [17.5%], odds ratio (OR) 0.45 (95% CI 0.09-2.24), p = 0.33). There were no malapposed struts in BP-SES group and 14 malapposed struts in EES group (p = 0.97). No difference in percent neointimal volume (14.1 ± 8.2% vs. 11.4 ± 6.4%, p = 0.56) was observed. Conclusions: Although rapid-breakdown BP-SES as compared to EES showed signs of improved early tissue coverage, after adjustment for strut-level clustering these differences were not statistically significant. No differences in ability to suppress neointimal hyperplasia after stent implantation between 2 stents were observed.

  18. 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.

  19. Multimodality Imaging of the Long-term Vascular Responses Following Implantation of Metallic and Bioresorbable Devices

    NARCIS (Netherlands)

    V.D. Gkogkas (Vasileios)

    2014-01-01

    markdownabstract__Abstract__ The pattern of vascular responses following stent/scaffold implantation in conventional interventional practice has been assessed by coronary angiography, intravascular ultrasound or optical coherence tomography and manifests as in-stent vascular response (focal or dif

  20. 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.

  1. Microfabrication and nanotechnology in stent design.

    Science.gov (United States)

    Martinez, Adam W; Chaikof, Elliot L

    2011-01-01

    Intravascular stents were first introduced in the 1980s as an adjunct to primary angioplasty for management of early complications, including arterial dissection, or treatment of an inadequate technical outcome due to early elastic recoil of the atherosclerotic lesion. Despite the beneficial effects of stenting, persistent high rates of restenosis motivated the design of drug-eluting stents for delivery of agents to limit the proliferative and other inflammatory responses within the vascular wall that contribute to the development of a restenotic lesion. These strategies have yielded a significant reduction in the incidence of restenosis, but challenges remain, including incomplete repair of the endothelium at the site of vascular wall injury that may be associated with a late risk of thrombosis. A failure of vessel wall healing has been attributed primarily to the use of polymeric stent coatings, but the effects of the eluted drug and other material properties or design features of the stent cannot be excluded. Improvements in stent microfabrication, as well as the introduction of alternative materials may help to address those limitations that inhibit stent performance. This review describes the application of novel microfabrication processes and the evolution of new nanotechnologies that hold significant promise in eliminating existing shortcomings of current stent platforms.

  2. 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.

  3. Traumatic aneurysm of the supraclinoid internal carotid artery and an associated carotid-cavernous fistula: vascular reconstruction performed using intravascular implantation of stents and coils. Case report.

    Science.gov (United States)

    Lee, Chang-Young; Yim, Man-Bin; Kim, Il-Man; Son, Eun-Ik; Kim, Dong-Won

    2004-01-01

    This report documents the treatment of a traumatic aneurysm of the supraclinoid internal carotid artery (ICA) that was associated with a carotid-cavernous fistula (CCF), which appeared following closed head trauma. This life-threatening lesion, which is very rare, required aggressive management achieved using intravascular stents and coils. A 19-year-old man presented with severe traumatic intracerebral and subarachnoid hematoma after he had suffered a severe closed head injury in a motor vehicle accident. Cerebral angiography performed 11 days after the injury demonstrated a traumatic aneurysm and severe narrowing of the right supraclinoid ICA, which was consistent with a dissection-induced stenosis associated with a direct CCF. Both lesions were successfully obliterated with preservation of the parent artery by using stents in conjunction with coils. Follow-up angiography obtained 7 months postoperatively revealed persistent obliteration of the aneurysm and CCF as well as patency of the parent artery. The patient remained asymptomatic during the clinical follow-up period of 14 months. Endovascular treatment involving the use of a stent combined with coils appears to be a feasible, minimally invasive option for treatment of this hard-to-treat lesion.

  4. 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.

  5. 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.

  6. The current status of stenting pathobiology.

    Science.gov (United States)

    Fleser, A; Leclerc, G

    1997-01-01

    Stents permanently maximize the arterial lumen following percutaneous transluminal coronary angioplasty (PTCA) at the cost of a vascular injury caused by the deployment of the prosthesis. Even though clinical trials show progressive reduction of restenosis and thrombosis rates in implanted coronary stents, these two events continue to represent a potential limitation to their clinical use. This review is focused on the arterial pathobiology related to the use of permanent and temporary stents. © 1997, Elsevier Science Inc. (Trends Cardiovasc Med 1997;7:24-28).

  7. 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.

  8. In vitro and in silico analysis of the vascular effects of asymmetrical N,N-bis(alkanol)amine aryl esters, novel multidrug resistance-reverting agents.

    Science.gov (United States)

    Fusi, F; Durante, M; Spiga, O; Trezza, A; Frosini, M; Floriddia, E; Teodori, E; Dei, S; Saponara, S

    2016-09-01

    Asymmetrical N,N-bis(alkanol)amine aryl esters (FRA77, GDE6, and GDE19) are potent multidrug resistance (MDR) reversers. Their structures loosely remind that of the Ca(2+) antagonist verapamil. Therefore, the aim of this study was to investigate their vascular activity in vitro. Their effects on the mechanical activity of fresh and cultured rat aorta rings on Cav1.2 channel current (I Ca1.2) of A7r5 cells and their cytotoxicity on A7r5 and EA.hy926 cells were analyzed. Docking at the rat α1C subunit of the Cav1.2 channel was simulated in silico. Compounds tested were cytotoxic at concentrations >1 μM (FRA77, GDE6, GDE19) and >10 μM (verapamil) in EA.hy926 cells, or >10 μM (FRA77, GDE6, GDE19) and at 100 μM (verapamil) in A7r5 cells. In fresh rings, the three compounds partly antagonized phenylephrine and 60 mM K(+) (K60)-induced contraction at concentrations ≥1 and ≥3 μM, respectively. On the contrary, verapamil fully relaxed rings pre-contracted with both agents. In cultured rings, 10 μM GDE6, GDE19, FRA77, and verapamil significantly reduced the contractile response to both phenylephrine and K60. Similarly to verapamil, the three compounds docked at the α1C subunit, interacting with the same amino acids residues. FRA77, GDE6, and GDE19 inhibited I Ca1.2 with IC50 values 1 order of magnitude higher than that of verapamil. FRA77-, GDE6-, and GDE19-induced vascular effects occurred at concentrations that are at least 1 order of magnitude higher than those effectively reverting MDR. Though an unambiguous divergence between MDR reverting and vascular activity is of overwhelming importance, these findings consistently contribute to the design and synthesis of novel and potent chemosensitizers.

  9. 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.

  10. 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.

  11. 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.)

  12. 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.

  13. 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.

  14. 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...

  15. 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.

  16. Emergency coronary stenting with the Palmaz-Schatz stent for failed transluminal coronary angioplasty: results of a learning phase.

    Science.gov (United States)

    Kiemeneij, F; Laarman, G J; van der Wieken, R; Suwarganda, J

    1993-07-01

    This study describes initial results of Palmaz-Schatz stent implantation in our department to restore and maintain vessel patency in 52 patients with obstructive dissection, defined as an intraluminal filling defect with coronary flow impairment after percutaneous transluminal coronary angioplasty (PTCA). The majority of patients (62%) underwent PTCA for unstable angina (n = 28), defined as angina at rest with documented ST segment changes resistant to nitrates, or acute myocardial infarction (n = 4). In six patients (11%) the stent could not be delivered. Seven of the remaining 46 patients (15%) had coronary artery bypass surgery performed because of increased risk for subacute stent occlusion, residual thrombosis, residual obstruction near the stent, coronary artery diameter less than 3.0 mm, or multiple and overlapping stents. One patient (3%) died in hospital from intracranial bleeding. Nine patients (23%) had subacute stent occlusion, retrospectively unpredictable in four patients. Nine of 29 patients (29%) with an uncomplicated clinical course after stenting had angiographic restenosis at a mean follow-up of 6.0 +/- 1.4 months (range 12 days to 8.3 months). Two patients (7%) died 3 months after successful stenting: one patient because of stent thrombosis after stopping warfarin before an abdominal operation and one patient after acute vascular surgery for late traumatic groin bleeding. Of the 39 medically treated patients with a stent, three (8%) had major bleeding complications. It is concluded that stent implantation is feasible in most patients with obstructive dissection after PTCA. After successful stent delivery, coronary flow is temporarily restored.(ABSTRACT TRUNCATED AT 250 WORDS)

  17. 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

  18. 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.

  19. Cost comparison between two modes of Palmaz Schatz coronary stent implantation: transradial bare stent technique vs. transfemoral sheath-protected stent technique.

    Science.gov (United States)

    Kiemeneij, F; Hofland, J; Laarman, G J; van der Elst, D H; van der Lubbe, H

    1995-08-01

    Coronary Palmaz Schatz stent implantation is usually performed by using the sheath protected stent delivery system (SDS) via the percutaneous transfemoral route. However, downsizing of PTCA equipment made transradial coronary stenting feasible. Bare stent implantation, 6F technique, increased patient mobility, reduced vascular complications and reduced hospital stay may increase cost effectiveness of this novel technique. Two well-documented patient groups selected for elective single vessel and single lesion Palmaz Schatz stent implantation were retrospectively compared. Group A (transradial stenting; n = 35) was compared to Group B (transfemoral stenting; n = 25) derived from the Benestent population, included in our hospital. A comparison was made for three areas of interest: (1) procedural consumption of material (the number of guiding catheters, guidewires, balloon catheters and stents), (2) postprocedural need for diagnostic and therapeutic procedures for stent-related complications, and (3) duration of hospital stay. Differences between these subjects in Group A and B were translated to hospital costs. Although more guiding catheters were used in group A (1.69 +/- 0.87 vs. 1.08 +/- 0.28; P = 0.001), the use of the SDS contributed importantly to higher material costs in group B (cost reduction in group A; 13%). Less patients in group A required diagnostic (2 vs. 7; P = 0.027) and therapeutic (0 vs. 5; P = 0.01) procedures for bleeding complications (cost reduction; 93%). Hospitalization in Group A was shorter (6.4 +/- 4.7 vs. 11.6 +/- 9.9 days; P = 0.005), caused by early and safe mobilization, less vascular complications, and preprocedural adjustment on coumadin (cost reduction; 45%).(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Magnetic resonance imaging of stents. Quantitative in vitro examination at 3 Tesla; Magnetresonanztomographie von Stents. Quantitative MR-Untersuchungen in vitro bei 3 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Reinhardt, Julia [Neurologische Universitaetsklinik Heidelberg (Germany). Sektion Experimentelle Radiologie; Fachhochschule Jena (Germany). Fachbereich Medizintechnik; Nguyen-Trong, Thien-Hoa; Haehnel, Stefan [Neurologische Universitaetsklinik Heidelberg (Germany). Abt. Neuroradiologie; Bellemann, Matthias E. [Fachhochschule Jena (Germany). Fachbereich Medizintechnik; Heiland, Sabine [Neurologische Universitaetsklinik Heidelberg (Germany). Sektion Experimentelle Radiologie; Neurologische Universitaetsklinik Heidelberg (Germany). Abt. Neuroradiologie

    2009-07-01

    The aim of this study was to qualitatively and quantitatively study MR artifacts of various stents on the basis of in vitro experiments. We were particularly interested whether sequence type and orientation of the stent with respect to the static magnetic field influences the artifact. We examined 18 stents of different material (nitinol, stainless steel, cobalt alloy), different design of the stent meshes (AccuLink, OmniLink, DynaLink, Xact, Protoge, Wallstent Monorail), different diameter (5-10 mm) and different length (18-58 mm) with a turbo spin echo (TSE), a 2D-fast low angle shot (FLASH) and a 3D-FLASH sequence. The MR images were examined qualitatively with respect to possible artifacts. Furthermore we examined the MR data quantitatively: The contrast-noise-ratio (CNR) was determined both within the stent and outside (within the tube); based on these values we calculated the transparency factor P, furthermore we calculated the apparent vascular lumen within the tube and within the stent. The stents made of stainless steel and cobalt alloy displayed severe susceptibility artifacts. Therefore the vessel lumen within the stent could not be assessed. The nitinol stents showed different artifact patterns: The AccuLink and DynaLink stents showed less artifacts compared to the Xact and Protoge stents. Besides the susceptibility artifacts we found artifacts due to RF shielding by the stent mesh, particularly in TSE sequences. A MR control of patients after stenting is possible and may yield diagnostic information when using the AccuLink or DynaLink stents. However, it is important to make sure that the stent is MR safe for the field strength used for the examination. (orig.)

  1. 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-

  2. 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

  3. Magnetizable stent-grafts enable endothelial cell capture

    Science.gov (United States)

    Tefft, Brandon J.; Uthamaraj, Susheil; Harburn, J. Jonathan; Hlinomaz, Ota; Lerman, Amir; Dragomir-Daescu, Dan; Sandhu, Gurpreet S.

    2017-04-01

    Emerging nanotechnologies have enabled the use of magnetic forces to guide the movement of magnetically-labeled cells, drugs, and other therapeutic agents. Endothelial cells labeled with superparamagnetic iron oxide nanoparticles (SPION) have previously been captured on the surface of magnetizable 2205 duplex stainless steel stents in a porcine coronary implantation model. Recently, we have coated these stents with electrospun polyurethane nanofibers to fabricate prototype stent-grafts. Facilitated endothelialization may help improve the healing of arteries treated with stent-grafts, reduce the risk of thrombosis and restenosis, and enable small-caliber applications. When placed in a SPION-labeled endothelial cell suspension in the presence of an external magnetic field, magnetized stent-grafts successfully captured cells to the surface regions adjacent to the stent struts. Implantation within the coronary circulation of pigs (n=13) followed immediately by SPION-labeled autologous endothelial cell delivery resulted in widely patent devices with a thin, uniform neointima and no signs of thrombosis or inflammation at 7 days. Furthermore, the magnetized stent-grafts successfully captured and retained SPION-labeled endothelial cells to select regions adjacent to stent struts and between stent struts, whereas the non-magnetized control stent-grafts did not. Early results with these prototype devices are encouraging and further refinements will be necessary in order to achieve more uniform cell capture and complete endothelialization. Once optimized, this approach may lead to more rapid and complete healing of vascular stent-grafts with a concomitant improvement in long-term device performance.

  4. Arterial stenting with self-expandable and balloon-expandable endoprostheses

    NARCIS (Netherlands)

    W.J. van der Giessen (Wim); P.W.J.C. Serruys (Patrick); L.J. van Woerkens (L.); K.J. Beatt (Kevin); W.J. Visser (W.); J.F. Jongkind; R.H. van Bremen (Robert); E. Ridderhof; H. van Loon (Heleen); L.K. Soei (Lou Kie); H.M.M. van Beusekom (Heleen); P.D. Verdouw (Pieter)

    1990-01-01

    textabstractCoronary angioplasty is complicated by acute occlusion (within 24 hours) and late restenosis (within 6 months) in 2-5% and 20-40% of the cases, respectively. Vascular endoprostheses (stents) may provide the cardiologist with a solution to some of these complications. Several stent-device

  5. 结合生物3D 打印和静电纺丝制备复合生物可吸收血管支架用于血管狭窄治疗%Composite bioabsorbable vascular stents via 3D bio-printing and electrospinning for treating stenotic vessels

    Institute of Scientific and Technical Information of China (English)

    刘媛媛; 向科; 李瑜; 陈海萍; 胡庆夕

    2015-01-01

    设计一种新型血管支架用于血管狭窄治疗。针对目前制备生物可吸收血管支架(BVS)在装备和技术上的不足,提出了结合生物3D 打印和静电纺丝制备复合生物可吸收血管支架(CBVS)的新方法。首先,用 PPDO材料通过3D 打印制备支架内层;然后,配制壳聚糖和 PVA 混合溶液,通过静电纺丝制备支架外层。力学性能测试显示,结合3D 打印和静电纺丝制备的支架要好于仅采用3D 打印制备的支架。在支架上种植细胞试验表明,细胞在支架上有良好的粘附和增殖,因为外层含有天然生物材料壳聚糖。所提出的复合成形工艺和方法,为后续构建可控携载药物支架提供了很好的思路。该 CBVS 可用于血管狭窄治疗。%A new type of vascular stent is designed for treating stenotic vessels.Aiming at overcoming the shortcomings of existing equipment and technology for preparing a bioabsorbable vascular stent (BVS),a new method which combines 3D bio-printing and electrospinning to prepare the composite bioabsorbable vascular stent (CBVS)is proposed. The inner layer of the CBVS can be obtained through 3D bio-printing using poly-p-dioxanone (PPDO).The thin nanofiber film that serves as the outer layer can be built through electrospinning using mixtures of chitosan-PVA (poly (vinyl alcohol)).Tests of mechanical properties show that the stent prepared through 3D bio-printing combined with electrospinning is better than that prepared through 3D bio-printing alone.Cells cultivated on the CBVS adhere and proliferate better due to the natural,biological chitosan in the outer layer.The proposed complex process and method can provide a good basis for preparing a controllable drug-carrying vascular stent.Overall,the CBVS can be a good candidate for treating stenotic vessels.

  6. 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....

  7. Biomechanical Challenges to Polymeric Biodegradable Stents.

    Science.gov (United States)

    Soares, Joao S; Moore, James E

    2016-02-01

    Biodegradable implants have demonstrated clinical success in simple applications (e.g., absorbable sutures) and have shown great potential in many other areas of interventional medicine, such as localized drug delivery, engineered tissue scaffolding, and structural implants. For endovascular stenting and musculoskeletal applications, they can serve as temporary mechanical support that provides a smooth stress-transfer from the degradable implant to the healing tissue. However, for more complex device geometries, in vivo environments, and evolving load-bearing functions, such as required for vascular stents, there are considerable challenges associated with the use of biodegradable materials. A biodegradable stent must restore blood flow and provide support for a predictable appropriate period to facilitate artery healing, and subsequently, fail safely and be absorbed in a controllable manner. Biodegradable polymers are typically weaker than metals currently employed to construct stents, so it is difficult to ensure sufficient strength to keep the artery open and alleviate symptoms acutely while keeping other design parameters within clinically acceptable ranges. These design challenges are serious, given the general lack of understanding of biodegradable polymer behavior and evolution in intimal operating conditions. The modus operandi is mainly empirical and relies heavily on trial-and-error methodologies burdened by difficult, resource-expensive, and time-consuming experiments. We are striving for theoretical advancements systematizing the empirical knowledge into rational frameworks that could be cast into in silico tools for simulation and product development optimization. These challenges are evident when one considers that there are no biodegradable stents on the US market despite more than 30 years of development efforts (and currently only a couple with CE mark). This review summarizes previous efforts at implementing biodegradable stents, discusses the

  8. Balloon-expandable covered stent therapy of complex endovascular pathology.

    Science.gov (United States)

    Giles, Heath; Lesar, Christopher; Erdoes, Luke; Sprouse, Richard; Myers, Stuart

    2008-11-01

    The current study was designed to investigate our hypotheses that balloon-expandable covered stents display acceptable function over longitudinal follow-up in patients with complex vascular pathology and provide a suitable alternative for the treatment of recurrent in-stent restenosis. All stents were Atrium iCast, which is a balloon-mounted, polytetrafluoroethylene-covered stent with a 6F/7F delivery system. A retrospective review was performed of 49 patients with 66 stented lesions. Data were analyzed with life tables and t-tests. The most commonly treated vessels were the iliac (61%) and renal (24%) arteries. Indications for covered stent placement were unstable atheromatous lesions (50%), recurrent in-stent restenosis (24%), aneurysm (8%), aortic bifurcation reconstruction (7.5%), dissection (4.5%), endovascular aneurysm repair-related (4.5%), and stent fracture (1.5%). Patency was assessed by angiogram or duplex ultrasonography. The primary end point was patency and secondary end points were technical success and access-site complications. Mean follow-up was 13 months (range 1.5-25). The technical success rate was 97%. Unsuccessful outcomes were due to deployment error (n=1) and stent malpositioning (n=1). The cohort (n=64) 6- and 12-month primary patency rates were 96% and 84%, respectively. Twelve-month assisted primary patency was 98%. Iliac artery stents (n=38) had a primary patency of 97% at 6 months and 84% at 12 months with an assisted primary patency of 100% at 12 months. Renal artery stents (n=16) had a primary patency of 92% at 6 months and 72% at 12 months with an assisted primary patency of 92% at 6 and 12 months. Stents placed for recurrent in-stent restenosis (n=16) had a primary patency of 85%, assisted primary patency of 93%, and a 15% restenosis rate at 12 months. Specifically, stents placed for renal artery recurrent in-stent restenosis (n=10) had a primary patency of 73%, assisted primary patency of 82%, and a restenosis rate of 27%. The

  9. Biocompatibility of Coronary Stents

    Directory of Open Access Journals (Sweden)

    Thamarasee M. Jeewandara

    2014-01-01

    Full Text Available Cardiovascular disease is the dominant cause of mortality in developed countries, with coronary artery disease (CAD a predominant contributor. The development of stents to treat CAD was a significant innovation, facilitating effective percutaneous coronary revascularization. Coronary stents have evolved from bare metal compositions, to incorporate advances in pharmacological therapy in what are now known as drug eluting stents (DES. Deployment of a stent overcomes some limitations of balloon angioplasty alone, but provides an acute stimulus for thrombus formation and promotes neointimal hyperplasia. First generation DES effectively reduced in-stent restenosis, but profoundly delay healing and are susceptible to late stent thrombosis, leading to significant clinical complications in the long term. This review characterizes the development of coronary stents, detailing the incremental improvements, which aim to attenuate the major clinical complications of thrombosis and restenosis. Despite these enhancements, coronary stents remain fundamentally incompatible with the vasculature, an issue which has largely gone unaddressed. We highlight the latest modifications and research directions that promise to more holistically design coronary implants that are truly biocompatible.

  10. In vitro comparison of self-expanding versus balloon-expandable stents in a human ex vivo model.

    Science.gov (United States)

    Grenacher, Lars; Rohde, Stefan; Gänger, Ellen; Deutsch, Jochen; Kauffmann, Günter W; Richter, Götz M

    2006-01-01

    The objective was to compare the radial strength and expansile precision of self-expanding stents and balloon-expandable stents in a human cadaver bifurcation model. Seven different self-expanding (LUMINEXX, JOSTENT SelfX, JOSTENT SelfX hrf, Sinus-Repo, Sinus SuperFlex, Easy Wallstent, SMART) and four different balloon-expandable stent models (Palmaz, Sinus Stent, SAXX Medium, JOSTENT peripheral), each type 10 stents (total n = 110 stents) were implanted into the common iliac arteries of human cadaver corpses. The maximum stent diameter was 10 mm for all models. After stent implantation, the specimens were filled with silicone caoutchouc. After 24 h, the vascular walls including the stents were removed from the hardened casts. Diameters were taken and the weight of the cast cylinders was measured in air and in purified water to calculate the volume of the bodies (according to Archimedes Law) as a relative but precise degree for the radial strength of the implanted stents. The cylindrical casts of the self-expanding stents showed lower mean diameters (8.2 +/- 1.0 mm) and mean volumes (0.60 +/- 0.14 ml/cm) than in the balloon-expandable stent group (10.1 +/- 0.3 mm and 0.71 +/- 0.04 ml/cm, respectively; p < 0.01). The nominal maximum diameter of 10 mm was not achieved in any of the self-expanding stents, but this was achieved in more than 70% (29/40) of the balloon-expandable stent specimens (p < 0.05). The variation between achieved volumes was significantly larger in self-expanding (range: 0.23-0.78 ml/cm) than in balloon-expandable stents (range: 0.66-0.81 ml/cm; p < 0.05). Self-expanding stents presented considerably lower radial expansion force and lower degree of precision than balloon-expandable stents.

  11. Surface chemical and physical modification in stent technology for the treatment of coronary artery disease.

    Science.gov (United States)

    Nazneen, Feroze; Herzog, Grégoire; Arrigan, Damien W M; Caplice, Noel; Benvenuto, Pasquale; Galvin, Paul; Thompson, Michael

    2012-10-01

    Coronary artery disease (CAD) kills millions of people every year. It results from a narrowing of the arteries (stenosis) supplying blood to the heart. This review discusses the merits and limitations of balloon angioplasty and stent implantation, the most common treatment options for CAD, and the pathophysiology associated with these treatments. The focus of the review is heavily placed on research efforts geared toward the modification of stent surfaces for the improvement of stent-vascular compatibility and the reduction in the occurrence of related pathophysiologies. Such modifications may be chemical or physical, both of which are surveyed here. Chemical modifications may be passive or active, while physical modification of stent surfaces can also provide suitable substrates to manipulate the responses of vascular cells (endothelial, smooth muscle, and fibroblast). The influence of micro- and nanostructured surfaces on the in vitro cell response is discussed. Finally, future perspectives on the combination of chemical and physical modifications of stent surfaces are also presented.

  12. Everolimus-eluting coronary stents

    Directory of Open Access Journals (Sweden)

    Alejandro Saez

    2010-09-01

    Full Text Available Alejandro Saez, Raul MorenoDivision of Interventional Cardiology, University Hospital La Paz, Madrid, SpainAbstract: Bare metal stents enabled a reduction in the risk of early procedural complications and restenosis in comparison with balloon angioplasty alone, but introduced a new and device-specific iatrogenic condition, ie, in-stent restenosis due to increased neointimal hyperplasia. Sirolimus- and paclitaxel-eluting stents reduce restenosis and the need for new revascularizations in comparison with bare metal stents, although at the cost of a slight increase in the risk of late stent thrombosis and a need for prolonged dual antiplatelet therapy. Everolimus is an analog of sirolimus with an increased solubility. In this review, the currently available evidence for everolimus-eluting stents is revised, including randomized trials against bare metal stents, and head-to-head trials comparing this stent with other drug-eluting stents.Keywords: coronary stents, restenosis, everolimus, review

  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. The development of self-expanding peripheral stent with ion-modified surface layer

    Science.gov (United States)

    Lotkov, Alexander I.; Kashin, Oleg A.; Kudryashov, Andrey N.; Krukovskii, Konstantin V.; Kuznetsov, Vladimir M.; Borisov, Dmitry P.; Kretov, Evgenii I.

    2016-11-01

    In work researches of chemical composition of surface layers of self-expanding stents of nickel-titanium (NiTi) and their functional and mechanical properties after plasma immersion processing by ions of silicon (Si). It is established that in the treatment in the inner and outer surfaces of stents formed doped silicon layer with a thickness of 80 nm. The formation of the doped layer does not impair the functional properties of the stent. At human body temperature, the stent is fully restore its shape after removing the deforming load. The resulting graph of loading of stents during their compression between parallel plates. The research results allow the conclusion that Si-doped stents are promising for treatment of peripheral vascular disease. However, related studies on laboratory animals are required.

  15. Functional Nanoarchitectures For Enhanced Drug Eluting Stents

    Science.gov (United States)

    Saleh, Yomna E.; Gepreel, Mohamed A.; Allam, Nageh K.

    2017-01-01

    Different strategies have been investigated to allow for optimum duration and conditions for endothelium healing through the enhancement of coronary stents. In this study, a nanoarchitectured system is proposed as a surface modification for drug eluting stents. Highly oriented nanotubes were vertically grown on the surface of a new Ni-free biocompatible Ti-based alloy, as a potential material for self-expandable stents. The fabricated nanotubes were self-grown from the potential stent substrate, which are also proposed to enhance endothelial proliferation while acting as drug reservoir to hinder Vascular Smooth Muscle Cells (VSMC) proliferation. Two morphologies were synthesized to investigate the effect of structure homogeneity on the intended application. The material was characterized by field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Nanoindentation technique was used to study the mechanical properties of the fabricated material. Cytotoxicity and proliferation studies were performed and compared for the two fabricated nanoarchitectures, versus smooth untextured samples, using in-vitro cultured endothelial cells. Finally, the drug loading capacity was experimentally studied and further supported by computational modeling of the release profile.

  16. 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

  17. Biodegradable Metals for Cardiovascular Stents: from Clinical Concerns to Recent Zn-Alloys.

    Science.gov (United States)

    Bowen, Patrick K; Shearier, Emily R; Zhao, Shan; Guillory, Roger J; Zhao, Feng; Goldman, Jeremy; Drelich, Jaroslaw W

    2016-05-01

    Metallic stents are used to promote revascularization and maintain patency of plaqued or damaged arteries following balloon angioplasty. To mitigate the long-term side effects associated with corrosion-resistant stents (i.e., chronic inflammation and late stage thrombosis), a new generation of so-called "bioabsorbable" stents is currently being developed. The bioabsorbable coronary stents will corrode and be absorbed by the artery after completing their task as vascular scaffolding. Research spanning the last two decades has focused on biodegradable polymeric, iron-based, and magnesium-based stent materials. The inherent mechanical and surface properties of metals make them more attractive stent material candidates than their polymeric counterparts. A third class of metallic bioabsorbable materials that are based on zinc has been introduced in the last few years. This new zinc-based class of materials demonstrates the potential for an absorbable metallic stent with the mechanical and biodegradation characteristics required for optimal stent performance. This review compares bioabsorbable materials and summarizes progress towards bioabsorbable stents. It emphasizes the current understanding of physiological and biological benefits of zinc and its biocompatibility. Finally, the review provides an outlook on challenges in designing zinc-based stents of optimal mechanical properties and biodegradation rate.

  18. Factors Associated with In-stent Restenosis in Patients Following Percutaneous Coronary Intervention

    Directory of Open Access Journals (Sweden)

    Dedi Wihanda

    2015-07-01

    Full Text Available Aim: to determine factors associated with In-Stent Restenosis (ISR in patients following Percutaneous Coronary Intervention (PCI. Methods: a retrospective cross-sectional study was conducted using secondary information from medical records of post-PCI patients who underwent follow-up of angiography PCI between January 2009 and March 2014 at The Integrated Cardiovascular Service Unit, Cipto Mangunkusumo Hospital, Jakarta. Angiographic ISR was defined when the diameter of stenosis ≥50% at follow-up angiography including the diameter inside the stent and diameter with five-mm protrusion out of the proximal and distal ends of the stent. Results: there were 289 subjects including 133 subjects with and 156 subjects without ISR. The incidence of ISR in patients using of bare-metal stent (BMS and drug-eluting stent (DES were 61.3% and 40.7%, respectively. Factors associated with ISR are stent-type (OR=4.83, 95% CI 2.51-9.30, stent length (OR=3.71, 95% CI 1.99-6.90, bifurcation lesions (OR=2.43, 95% CI 1.16-5.10, smoking (OR=2.30, 95% CI 1.33-3.99, vascular diameter (OR=2.18, 95% CI 1.2-3.73, hypertension (OR=2.16, 95% CI 1.16-4.04 and diabetes mellitus (OR=2.14, 95% CI 1.23-3.70. Conclusion: stent type, stent length, bifurcation lesions, smoking, vascular diameter, hypertension and DM are factors associated with ISR in patients following PCI. Key words: bare-metal stent; drug-eluting stent; in-stent restenosis.

  19. 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....

  20. Stenting of the SFA - indications, techniques,; Stents in der A. femoralis superficialis - Indikationen, Technik, Ergebnisse

    Energy Technology Data Exchange (ETDEWEB)

    Rieger, J.; Treitl, M.; Reiser, M. [Klinikum Innenstadt der Ludwigs-Maximilians-Universitaet,, Muenchen (Germany). Institut fuer Klinische Radiologie; Ruppert, V. [Chirurgische Klinik und Poliklinik Innenstadt - Klinikum der Ludwigs-Maximilians-Universitaet Muenchen (Germany). Funktionsbereich Gefaesschirurgie

    2006-11-15

    Aggressive risk factor modification, change of eating habits, exercise programs, and forceful antiplatelet therapy are the most important tools for the treatment of PAOD in symptomatic patients suffering from intermittent claudication. There are however no guidelines for revascularization at this stage. Endovascular treatment has been increasingly utilized over the last decade and increasingly displaced vascular surgery. Amongst numerous endovascular techniques beside PTA, stents meanwhile play the most important role due to constant technical progress. Results regarding the rate of restenosis or patency rates still remain worse compared to other vascular beds. This paper gives a review over recent results, currently available stent techniques, and possible indications for the endovascular therapy of an artery, which has turned out to be the biggest ordeal for material and construction of stents. (orig.) [German] Aggressives Risikofaktorenmanagement, Aenderungen der Lebens- und Essgewohnheiten sowie eine konsequente antithrombotische Therapie sind die wichtigsten Saeulen bei der Sekundaerprophylaxe einer symptomatischen peripheren arteriellen Verschlusskrankheit (PAVK) im Stadium der Claudicatio. Bei den revaskularisierenden Verfahren existieren in diesem Stadium keine verbindlichen Richtlinien zur Indikationsstellung. Endovaskulaere Techniken draengen jedoch den klassischen Bypass mehr und mehr zurueck. Unter den zahlreichen endovaskulaeren Therapiemoeglichkeiten haben sich in der A. femoralis superficialis (AFS) neben der perkutanen transfemoralen Angioplastie (PTA) v. a. technisch immer weiter verbesserte Stents etabliert. Die Ergebnisse bzgl. der Inzidenz von Restenosen bzw. der Offenheitsraten fallen aber weiterhin im Vergleich zu anderen arteriellen Stromgebieten schlechter aus. Dieser Artikel gibt einen Ueberblick ueber die z. Z. einsetzbaren Stentmodelle, moegliche Indikationen und die juengsten Ergebnisse der endovaskulaeren Behandlung eines Gefaesses, das

  1. Renal Artery Stent Outcomes

    Science.gov (United States)

    Murphy, Timothy P.; Cooper, Christopher J.; Matsumoto, Alan H.; Cutlip, Donald E.; Pencina, Karol M.; Jamerson, Kenneth; Tuttle, Katherine R.; Shapiro, Joseph I.; D’Agostino, Ralph; Massaro, Joseph; Henrich, William; Dworkin, Lance D.

    2016-01-01

    BACKGROUND Multiple randomized clinical trials comparing renal artery stent placement plus medical therapy with medical therapy alone have not shown any benefit of stent placement. However, debate continues whether patients with extreme pressure gradients, stenosis severity, or baseline blood pressure benefit from stent revascularization. OBJECTIVES The study sought to test the hypothesis that pressure gradients, stenosis severity, and/or baseline blood pressure affects outcomes after renal artery stent placement. METHODS Using data from 947 patients with a history of hypertension or chronic kidney disease from the largest randomized trial of renal artery stent placement, the CORAL (Cardiovascular Outcomes in Renal Atherosclerotic Lesions) study, we performed exploratory analyses to determine if subsets of patients experienced better outcomes after stent placement than the overall cohort. We examined baseline stenosis severity, systolic blood pressure, and translesion pressure gradient (peak systolic and mean) and performed interaction tests and Cox proportional hazards analyses for the occurrence of the primary endpoint through all follow-up, to examine the effect of these variables on outcomes by treatment group. RESULTS There were no statistically significant differences in outcomes based on the examined variables nor were there any consistent nonsignificant trends. CONCLUSIONS Based on data from the CORAL randomized trial, there is no evidence of a significant treatment effect of the renal artery stent procedure compared with medical therapy alone based on stenosis severity, level of systolic blood pressure elevation, or according to the magnitude of the transstenotic pressure gradient. (Benefits of Medical Therapy Plus Stenting for Renal Atherosclerotic Lesions [CORAL]; NCT00081731) PMID:26653621

  2. 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.)

  3. 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.

  4. A novel electrical potential sensing method for in vitro stent fracture monitoring and detection.

    Science.gov (United States)

    Park, Chan-Hee; Tijing, Leonard D; Yun, Yeoheung; Kim, Cheol Sang

    2011-01-01

    This article describes a preliminary investigation and prototype fabrication of a novel potential sensing method to continuously monitor vascular stent fractures. A potential measurement system consisting of Wheatstone bridge circuit and signal conditioning circuit was designed for the cardiovascular stent durability and fatigue test. Each end of a bare and polyurethane-covered Nitinol vascular stent was electrically connected to the potential measurement system and then immersed either in simulated body fluid (SBF) media or distilled water at 36.4 ± 1 °C. When the stent experienced fracture (i.e., a cut), its electrical potential decreased with an increase in electrical resistance. This method successfully measured fractures in the stent regardless of location. Furthermore, the number of cycles at the onset of stent fracture was accurately detected and continuously monitored using this technique. Thus, the present fracture detection method, which to our knowledge is the first ever report to use electrical potential measurement for stent durability test, gives a fast, real-time, accurate and efficient detection of fractures in stent during in vitro fatigue and durability test.

  5. 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.

  6. Implantation study of a tissue-engineered self-expanding aortic stent graft (bio stent graft) in a beagle model.

    Science.gov (United States)

    Kawajiri, Hidetake; Mizuno, Takeshi; Moriwaki, Takeshi; Iwai, Ryosuke; Ishibashi-Ueda, Hatsue; Yamanami, Masashi; Kanda, Keiichi; Yaku, Hitoshi; Nakayama, Yasuhide

    2015-03-01

    The use of stent grafts for endovascular aortic repair has become an important treatment option for aortic aneurysms requiring surgery. This treatment has achieved excellent outcomes; however, problems like type 1 endoleaks and stent graft migration remain. Bio stent grafts (BSGs), which are self-expanding stents covered with connective tissue, were previously developed using "in-body tissue architecture" technology. We assessed their early adaptation to the aorta after transcatheter implantation in a beagle model. BSGs were prepared by subcutaneous embedding of acryl rods mounted with self-expanding nitinol stents in three beagles for 4 weeks (n = 3/dog). The BSGs were implanted as allografts into infrarenal abdominal aortas via the femoral artery of three other beagles. After 1 month of implantation, aortography revealed no stenosis or aneurysmal changes. The luminal surface of the BSGs was completely covered with neointimal tissue, including endothelialization, without any thrombus formation. The cover tissue could fuse the luminal surface of the native aorta with tight conjunctions even at both ends of the stents, resulting in complete impregnation of the strut into the reconstructed vascular wall, which is expected to prevent endoleaks and migration in clinical applications.

  7. 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.

  8. Cobalt chromium stents versus stainless steel stents in diabetic patients

    Directory of Open Access Journals (Sweden)

    Mahmoud Ahmed Tantawy

    2014-03-01

    Conclusions: We concluded that no significant statistical difference was found between the two stents (cobalt-chromium alloy bare metal stent versus conventional bare metal stainless steel stent in diabetic patients regarding (initial procedural success, in-hospital complications, the incidence of ISR at follow up, event-free survival at follow up.

  9. Point-of-care seeding of nitinol stents with blood-derived endothelial cells.

    Science.gov (United States)

    Jantzen, Alexandra E; Noviani, Maria; Mills, James S; Baker, Katherine M; Lin, Fu-Hsiung; Truskey, George A; Achneck, Hardean E

    2016-11-01

    Nitinol-based vascular devices, for example, peripheral and intracranial stents, are limited by thrombosis and restenosis. To ameliorate these complications, we developed a technology to promote vessel healing by rapidly seeding (QuickSeeding) autologous blood-derived endothelial cells (ECs) onto modified self-expanding nitinol stent delivery systems immediately before implantation. Several thousand micropores were laser-drilled into a delivery system sheath surrounding a commercial nitinol stent to allow for exit of an infused cell suspension. As suspension medium flowed outward through the micropores, ECs flowed through the delivery system attaching to the stent surface. The QuickSeeded ECs adhered to and spread on the stent surface following 24-h in vitro culture under static or flow conditions. Further, QuickSeeded ECs on stents that were deployed into porcine carotid arteries spread to endothelialize stent struts within 48 h (n = 4). The QuickSeeded stent struts produced significantly more nitric oxide in ex vivo flow circuits after 24 h, as compared to static conditions (n = 5). In conclusion, ECs QuickSeeded onto commercial nitinol stents within minutes of implantation spread to form a functional layer in vitro and in vivo, providing proof of concept that the novel QuickSeeding method with modified delivery systems can be used to seed functional autologous endothelium at the point of care. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1658-1665, 2016.

  10. 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

  11. Multimodality Imaging of the Long-term Vascular Responses Following Implantation of Metallic and Bioresorbable Devices

    OpenAIRE

    Gkogkas, Vasileios

    2014-01-01

    markdownabstract__Abstract__ The pattern of vascular responses following stent/scaffold implantation in conventional interventional practice has been assessed by coronary angiography, intravascular ultrasound or optical coherence tomography and manifests as in-stent vascular response (focal or diffuse) or as edge vascular response (EVR) at the transition zones (focal). The utilization of bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals for coronary revacularizati...

  12. Successful Endobronchial stenting for bronchial compression from a massive thoracic aortic aneurysm

    Directory of Open Access Journals (Sweden)

    David Comer

    2010-06-01

    Full Text Available A case of bronchial occlusion caused by a thoracic aortic aneurysm and the relief of this obstruction by the implantation of expandable metallic stents is described. Stent deployment provided an immediate improvement in lung ventilation and chest radiograph appearances. Stent insertion was uncomplicated, but weaning from mechanical ventilation was unsuccessful and the patient died from a ventilator-associated pneumonia, unrelated to the procedure. Endobronchial stenting should be considered as a non-invasive therapy for the treatment of bronchial obstruction, with respiratory compromise, caused by a thoracic aortic aneurysm when vascular surgery is not an option. The medium to long term survival of this patient group is poor. This can be attributed to complications related to the stent and also to the poor performance status of these patients.

  13. 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.

  14. Transradial artery Palmaz-Schatz coronary stent implantation: results of a single-center feasibility study.

    Science.gov (United States)

    Kiemeneij, F; Laarman, G J

    1995-07-01

    The purpose of this study was to evaluate the feasibility and safety of implantation of unsheathed Palmaz-Schatz coronary stents introduced via the radial artery. Anticoagulation after coronary stenting carries the risk of vascular complications if large-bore guiding catheters are introduced via the femoral artery. These complications have serious local sequelae and lead to suboptimal anticoagulation and prolonged hospitalization. By combining 6F guiding catheters and low-profile dilatation catheters mounted with Palmaz-Schatz stents, smaller vessels such as the radial artery can be selected as the entry site. It is hypothesized that with this technique major puncture site-related complications rarely occur because hemostasis is easily achieved and because no veins and nerves are near this artery. With the double blood supply to the hand, radial artery occlusion is well tolerated. In 100 consecutive patients, stent implantation was attempted for 122 lesions in 104 vessels. Immediately after stent implantation and final angiography, the introducer sheath was withdrawn and intense anticoagulation and mobilization initiated. The radial artery puncture site was studied by two-dimensional and Doppler ultrasound. Successful stent implantation via the radial artery was achieved in 96 patients. In 2 patients, arterial puncture failed but was followed by successful stenting via another entry site. In 1 patient, stent implantation was achieved with a stent delivery system via the femoral artery after a failed attempt to cross the lesion with a bare stent via the radial approach, complicated by groin bleeding requiring transfusions and vascular surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. 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...

  16. 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.

  17. 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

  18. Vascular Cures

    Science.gov (United States)

    ... Contact Us Vascular Disease What is Vascular Disease? Education and Awareness Vascular Diseases Abdominal Aortic Aneurysm Aortic Dissection Arteriovenous Malformation Atherosclerosis Buerger's Disease Carotid Artery Disease ...

  19. Preventive percutaneous radiation therapy to avoid hyperplasia of the intima after angioplasty combined with stent-implantation. Praeventive perkutane Strahlentherapie zur Vermeidung von Intimahyperplasie nach Angioplastie mit Stentimplantation

    Energy Technology Data Exchange (ETDEWEB)

    Steidle, B. (Radiologische Klinik, St.-Elisabethen-Krankenhaus, Ravensburg (Germany))

    1994-03-01

    A total of 24 patients had a stent implanted in their superficial femoral artery from 1990 to 1992. Eleven patients received percutaneous radiation therapy of the enlarged stent area on five consecutive days with a single dose of 2.5 Gy thus resulting in a total dose of 12.5 Gy. Both patients groups were compared. None of the patients in the radiation group suffered from complications. In the seven months following stent implantation and radiation only two of eleven patients in the radiation group suffered from occlusion of the stent that had to be treated by vascular surgery. In comparison five of 13 patients treated with stent implantation alone suffered from occlusion of the stent within the first eight to nine months. In spite of a small case number our study shows a positive influence of percutaneous radiation therapy on the extent of hyperplasia of the intima after stent implantation leading to lower reocclusion rates. (orig./MG)

  20. Impact of the distance from the stent edge to the residual plaque on edge restenosis following everolimus-eluting stent implantation.

    Directory of Open Access Journals (Sweden)

    Masao Takahashi

    Full Text Available OBJECTIVES: This study aimed to assess the relation between stent edge restenosis (SER and the distance from the stent edge to the residual plaque using quantitative intravascular ultrasound. BACKGROUND: Although percutaneous coronary intervention with drug-eluting stents has improved SER rates, determining an appropriate stent edge landing zone can be challenging in cases of diffuse plaque lesions. It is known that edge vascular response can occur within 2 mm from the edge of a bare metal stent, but the distance to the adjacent plaque has not been evaluated for drug-eluting stents. METHODS: A total of 97 proximal residual plaque lesions (plaque burden [PB] >40% treated with everolimus-eluting stents were retrospectively evaluated to determine the distance from the stent edge to the residual plaque. RESULTS: The SER group had significantly higher PB (59.1 ± 6.1% vs. 51.9 ± 9.1% for non-SER; P = 0.04. Higher PB was associated with SER, with the cutoff value of 54.74% determined using receiver operating characteristic (ROC curve analysis. At this cutoff value of PB, the distance from the stent edge to the lesion was significantly associated with SER (odds ratio = 2.05, P = 0.035. The corresponding area under the ROC curve was 0.725, and the cutoff distance value for predicting SER was 1.0 mm. CONCLUSION: An interval less than 1 mm from the proximal stent edge to the nearest point with the determined PB cutoff value of 54.74% was significantly associated with SER in patients with residual plaque lesions.

  1. Expandable bioresorbable endovascular stent. I. Fabrication and properties.

    Science.gov (United States)

    Su, Shih-Horng; Chao, Robert Y N; Landau, Charles L; Nelson, Kevin D; Timmons, Richard B; Meidell, Robert S; Eberhart, Robert C

    2003-06-01

    A bioresorbable, expandable poly(L-lactic acid) stent has been designed, based on a linear, continuous coil array principle, by which multiple furled lobes convert to a single lobe upon balloon expansion, without heating. Stent strength and compliance are sufficient to permit deployment by a conventional balloon angioplasty catheter. Several multiple lobe configurations were investigated, with expansion ratios ranging from 1.4 to 1.9 and expanded diameters ranging from 2.3 to 4.7 mm. Compression resistance of the expanded stent is dependent on fiber coil density and fiber ply. A range sufficient for endovascular service was obtained, with less than 4% elastic recoil in six day saline incubation studies. Surface plasma treatment with di(ethylene glycol) vinyl ether significantly reduced platelet adhesion in a 1 h porcine arteriovenous shunt model. Patency was maintained in one week implant studies in the porcine common femoral artery. However, a strong inflammatory response, and significant reduction of the vascular lumen were observed following two weeks implantation. The design principles and fabrication techniques for this bioresorbable stent are sufficiently versatile that a broad range of applications can be addressed. Much work remains to be done, including long-term evaluation of the inflammatory response, and of polymer degradation. The results of this study demonstrate the feasibility of expandable biodegradable stent design and deployment by conventional means.

  2. Ultrasound -- Vascular

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Ultrasound - Vascular Vascular ultrasound uses sound waves to evaluate ... the limitations of Vascular Ultrasound? What is Vascular Ultrasound? Ultrasound is safe and painless, and produces pictures ...

  3. 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.

  4. 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.

  5. 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 ...

  6. 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.

  7. Carotid artery stenting: which stent for which lesion?

    Science.gov (United States)

    Bosiers, Marc; Deloose, Koen; Verbist, Jürgen; Peeters, Patrick

    2005-01-01

    The different geometries and working principles of carotid stents (nitinol or cobalt chromium, open- or closed-cell configuration) provide each product with unique functional properties. The individual characteristics of each device may make it an attractive choice in one circumstance but render it less desirable in other situations. In approximately 75% of all procedures, all types of stents will achieve similar outcomes, making adequate device selection unnecessary. For the remaining quarter, careful preoperative screening is mandatory. In addition to eventual access issues, the choice of the optimal carotid stent depends mainly on arterial anatomy and lesion morphology. When treating a tortuous anatomy, stents with a flexible and comformable open-cell configuration are preferred. In arteries with a significant mismatch between common carotid artery and internal carotid artery diameter, cobalt chromium (Elgiloy) or tapered nitinol stents are selected. Lesions with suspected high emboligenicity are best covered with stents with a closed-cell configuration, whereas highly calcified lesions need treatment with nitinol stents. Thorough knowledge of the characteristics, advantages and disadvantages, and working principles of the different available stents is mandatory to optimally select the materials to be used for patients eligible for carotid revascularization.

  8. 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.

  9. 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)

  10. 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

  11. A new removable airway stent

    Directory of Open Access Journals (Sweden)

    Tore Amundsen

    2016-09-01

    Full Text Available Background: Malignant airway obstruction is a feared complication and will most probably occur more frequently in the future because of increasing cancer incidence and increased life expectancy in cancer patients. Minimal invasive treatment using airway stents represents a meaningful and life-saving palliation. We present a new removable airway stent for improved individualised treatment. Methods: To our knowledge, the new airway stent is the world's first knitted and uncovered self-expanding metal stent, which can unravel and be completely removed. In an in vivo model using two anaesthetised and spontaneously breathing pigs, we deployed and subsequently removed the stents by unravelling the device. The procedures were executed by flexible bronchoscopy in an acute and a chronic setting – a ‘proof-of-principle’ study. Results: The new stent was easily and accurately deployed in the central airways, and it remained fixed in its original position. It was easy to unravel and completely remove from the airways without clinically significant complications. During the presence of the stent in the chronic study, granulation tissue was induced. This tissue disappeared spontaneously with the removal. Conclusions: The new removable stent functioned according to its purpose and unravelled easily, and it was completely removed without significant technical or medical complications. Induced granulation tissue disappeared spontaneously. Further studies on animals and humans are needed to define its optimal indications and future use.

  12. Heparin-Coated Coronary Stents.

    Science.gov (United States)

    van Der Giessen WJ; van Beusekom HM; Larsson; Serruys

    1999-09-01

    The development of the heparin-coated (HC)-stent should be viewed against the backdrop of the early unfavorable results with noncoated stents in the pre-intravascular ultrasound and pre-ticlopidine era. Notwithstanding, results of pilot and randomized trials show a surprisingly low incidence of (sub)acute stent thrombosis under challenging circumstances, such as acute coronary syndromes. Considering the quite low incidence of early complications with noncoated second-generation stents, it may require large trials to prove the clinical efficacy of the heparin- coating against noncoated devices. However, even if the "added value" of the heparin-coating will never be clinically proven, it has helped to enhance the penetration of stent therapy in interventional cardiology. Unlike the situation in 1992, very few cardiologists will now disagree with the statement that stents contribute to the state-of-the-art treatment of patients with angina pectoris or acute myocardial infarction. A preliminary comparison of available trials also suggests that the heparin-coated Palmaz-Schatz stent (Cordis Corp., Waterloo, Belgium) is as effective as the noncoated stent plus abciximab treatment.

  13. Stents for malignant ureteral obstruction

    Directory of Open Access Journals (Sweden)

    Kristina Pavlovic

    2016-07-01

    Full Text Available Malignant ureteral obstruction can result in renal dysfunction or urosepsis and can limit the physician's ability to treat the underlying cancer. There are multiple methods to deal with ureteral obstruction including regular polymeric double J stents (DJS, tandem DJS, nephrostomy tubes, and then more specialized products such as solid metal stents (e.g., Resonance Stent, Cook Medical and polyurethane stents reinforced with nickel-titanium (e.g., UVENTA stents, TaeWoong Medical. In patients who require long-term stenting, a nephrostomy tube could be transformed subcutaneously into an extra-anatomic stent that is then inserted into the bladder subcutaneously. We outline the most recent developments published since 2012 and report on identifiable risk factors that predict for failure of urinary drainage. These failures are typically a sign of cancer progression and the natural history of the disease rather than the individual type of drainage device. Factors that were identified to predict drainage failure included low serum albumin, bilateral hydronephrosis, elevated C-reactive protein, and the presence of pleural effusion. Head-to-head studies show that metal stents are superior to polymeric DJS in terms of maintaining patency. Discussions with the patient should take into consideration the frequency that exchanges will be needed, the need for externalized hardware (with nephrostomy tubes, or severe urinary symptoms in the case of internal DJS. This review will highlight the current state of diversions in the setting of malignant ureteral obstruction.

  14. 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.

  15. Use of Micropatterned Thin Film Nitinol in Carotid Stents to Augment Embolic Protection

    Science.gov (United States)

    Shayan, Mahdis; Jankowitz, Brian T.; Shridhar, Puneeth; Chun, Youngjae

    2016-01-01

    Stenting is an alternative to endarterectomy for the treatment of carotid artery stenosis. However, stenting is associated with a higher risk of procedural stroke secondary to distal thromboembolism. Hybrid stents with a micromesh layer have been proposed to address this complication. We developed a micropatterned thin film nitinol (M-TFN) covered stent designed to prevent thromboembolism during carotid intervention. This innovation may obviate the need or work synergistically with embolic protection devices. The proposed double layered stent is low-profile, thromboresistant, and covered with a M-TFN that can be fabricated with fenestrations of varying geometries and sizes. The M-TFN was created in multiple geometries, dimensions, and porosities by sputter deposition. The efficiency of various M-TFN to capture embolic particles was evaluated in different atherosclerotic carotid stenotic conditions through in vitro tests. The covered stent prevented emboli dislodgement in the range of 70%–96% during 30 min duration tests. In vitro vascular cell growth study results showed that endothelial cell elongation, alignment and growth behaviour silhouettes significantly enhance, specifically on the diamond-shape M-TFN, with the dimensions of 145 µm × 20 µm and a porosity of 32%. Future studies will require in vivo testing. Our results demonstrate that M-TFN has a promising potential for carotid artery stenting. PMID:27983574

  16. Use of Micropatterned Thin Film Nitinol in Carotid Stents to Augment Embolic Protection

    Directory of Open Access Journals (Sweden)

    Mahdis Shayan

    2016-12-01

    Full Text Available Stenting is an alternative to endarterectomy for the treatment of carotid artery stenosis. However, stenting is associated with a higher risk of procedural stroke secondary to distal thromboembolism. Hybrid stents with a micromesh layer have been proposed to address this complication. We developed a micropatterned thin film nitinol (M-TFN covered stent designed to prevent thromboembolism during carotid intervention. This innovation may obviate the need or work synergistically with embolic protection devices. The proposed double layered stent is low-profile, thromboresistant, and covered with a M-TFN that can be fabricated with fenestrations of varying geometries and sizes. The M-TFN was created in multiple geometries, dimensions, and porosities by sputter deposition. The efficiency of various M-TFN to capture embolic particles was evaluated in different atherosclerotic carotid stenotic conditions through in vitro tests. The covered stent prevented emboli dislodgement in the range of 70%–96% during 30 min duration tests. In vitro vascular cell growth study results showed that endothelial cell elongation, alignment and growth behaviour silhouettes significantly enhance, specifically on the diamond-shape M-TFN, with the dimensions of 145 µm × 20 µm and a porosity of 32%. Future studies will require in vivo testing. Our results demonstrate that M-TFN has a promising potential for carotid artery stenting.

  17. 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.

  18. 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...

  19. [Longitudinal stent deformation during bifurcation lesion treatment].

    Science.gov (United States)

    Mami, Z; Monsegu, J

    2014-12-01

    Longitudinal stent deformation is defined as a compression of stent length after its implantation. It's a rare complication but dangerous seen with several stents. We reported a case of longitudinal stent deformation during bifurcation lesion treatment with a Promus Element(®) and we perform a short review of this complication.

  20. 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

  1. 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.)

  2. Drug-eluting stents in the management of peripheral arterial disease

    Directory of Open Access Journals (Sweden)

    Marc Bosiers

    2008-06-01

    Full Text Available Marc Bosiers1, Catherine Cagiannos1, Koen Deloose1, Jürgen Verbist2, Patrick Peeters21Department of Vascular Surgery, AZ St-Blasius, Dendermonde, Belgium; 2Department of Cardiovascular and Thoracic Surgery, Imelda Hospital, Bonheiden, BelgiumAbstract: Since major meta-analyses of randomized controlled trials in interventional cardiology showed the potential of drug-eluting stents in decreasing restenosis and reintervention rates after coronary artery stenting, one of the next steps in the treatment of arterial occlusive disease is the transfer of the active coating technology towards peripheral arterial interventions. In this manuscript, we aim to provide a literature overview on available peripheral (lower limb, renal, and supra-aortic drug-eluting stent applications, debate the cost implications, and give recommendations for future treatment strategies.Keywords: critical limb ischemia, drug-eluting stent, below the knee, infrapopliteal, crural, limb salvage

  3. Infection of endovascular abdominal aortic aneurysm stent graft after urosepsis: case report and review of the literature.

    Science.gov (United States)

    Veger, H T C; Hedeman Joosten, P Ph; Thoma, S R; Visser, M J T

    2013-02-01

    Infection of endovascular abdominal aneurysm stent grafts is an uncommon but known complication. Inoculation with bacteria of the endovascular abdominal aneurysm stent graft during the actual implantation, in the periprocedural hospitalization or later due to an aortoenteric fistula, has been described in the literature. We report a case of endovascular abdominal aortic aneurysm stent graft infection occurring 40 months after implantation in a patient doing well up to an episode of urosepsis. In conclusion, we postulate that poor intraluminal healing of stent grafts, as observed in several explant studies, may result in a higher susceptibility to episodes of bacteremia than prosthetic vascular grafts inserted during open repair. We therefore consider the administration of prophylactic antibiotics in patients with endovascular stent grafts during periods with a likelihood of bacteremia.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Present and future of endovascular SFA treatment: stents, stent-grafts, drug coated balloons and drug coated stents.

    Science.gov (United States)

    Bosiers, M; Deloose, K; Verbist, J; Peeters, P

    2008-04-01

    The current evolution towards treating more complex femoropopliteal lesions as seen in the renewed TASC II recommendations clearly reflects the continuous evolutions in femoropopliteal stent design. Recent stent design improvements focus on decreasing stent fractures rates which can negatively impact patency rates. By rearranging strut alignment towards helical connecting bridges or full helical stent designs, stent designers have successfully improved the fracture resistance of their stents. The superior fracture resistance of the latest stent generation in combination with the production of long nitinol stents of up to 20 cm in length allow that more difficult and complex lesions can be treated endovascularly. The continuous perfection of nitinol stent platforms followed by the transfer of coronary technologies (e.g. active coatings) towards peripheral devices might broaden the indications for the minimal invasive strategy towards TransAtlantic Inter-Society Consensus (TASC) II C&D lesions.

  11. 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.

  12. Novel side branch ostial stent.

    Science.gov (United States)

    Chen, Shao-Liang; Lv, Shu-Zheng; Kwan, Tak W

    2009-04-01

    Bifurcation lesions are technically challenging and plagued by a high incidence of restenosis, especially at the side branch orifice, which results in a more frequent need for revascularization during the follow-up period. This report discusses two clinical experiences with a novel side branch ostial stent, the BIGUARD stent, designed for the treatment of bifurcation lesions; procedural success with no in-hospital complications was observed in types IVb and Ia lesions.

  13. In vivo response of AZ31 alloy as biliary stents: a 6 months evaluation in rabbits

    Science.gov (United States)

    Liu, Yang; Zheng, Shengmin; Li, Nan; Guo, Huahu; Zheng, Yufeng; Peng, Jirun

    2017-01-01

    Mg-based metallic materials have been making continuing progress as vascular stents. However, the research of Mg-based materials as non-vascular stents is still at its primary stage. AZ31 stents hereby were implanted into the common bile duct of rabbits for 6 months. The results revealed an existence of 93.82 ± 1.36% and 30.89 ± 2.46% of the original volume after 1 and 3 month, respectively. Whole blood tests indicated an inflammation decreasing to normal level after 3 month implantation. A benign host response was observed via H&E staining. Nonuniform corrosion at the two ends of the stents was observed and considered the results of flow or local inflammation. Moreover, the application of Mg-based materials for different stenting treatment were reviewed and compared. Esophagus was hypothesized most destructive, whilst blood vessel and bile duct considered similar and less destructive. Trachea and nasal cavity were thought to be mildest.

  14. In vivo response of AZ31 alloy as biliary stents: a 6 months evaluation in rabbits

    Science.gov (United States)

    Liu, Yang; Zheng, Shengmin; Li, Nan; Guo, Huahu; Zheng, Yufeng; Peng, Jirun

    2017-01-01

    Mg-based metallic materials have been making continuing progress as vascular stents. However, the research of Mg-based materials as non-vascular stents is still at its primary stage. AZ31 stents hereby were implanted into the common bile duct of rabbits for 6 months. The results revealed an existence of 93.82 ± 1.36% and 30.89 ± 2.46% of the original volume after 1 and 3 month, respectively. Whole blood tests indicated an inflammation decreasing to normal level after 3 month implantation. A benign host response was observed via H&E staining. Nonuniform corrosion at the two ends of the stents was observed and considered the results of flow or local inflammation. Moreover, the application of Mg-based materials for different stenting treatment were reviewed and compared. Esophagus was hypothesized most destructive, whilst blood vessel and bile duct considered similar and less destructive. Trachea and nasal cavity were thought to be mildest. PMID:28084306

  15. Flow-induced corrosion behavior of absorbable magnesium-based stents.

    Science.gov (United States)

    Wang, Juan; Giridharan, Venkataraman; Shanov, Vesselin; Xu, Zhigang; Collins, Boyce; White, Leon; Jang, Yongseok; Sankar, Jagannathan; Huang, Nan; Yun, Yeoheung

    2014-12-01

    The aim of this work was to study corrosion behavior of magnesium (Mg) alloys (MgZnCa plates and AZ31 stents) under varied fluid flow conditions representative of the vascular environment. Experiments revealed that fluid hydrodynamics, fluid flow velocity and shear stress play essential roles in the corrosion behavior of absorbable magnesium-based stent devices. Flow-induced shear stress (FISS) accelerates the overall corrosion (including localized, uniform, pitting and erosion corrosions) due to the increased mass transfer and mechanical force. FISS increased the average uniform corrosion rate, the localized corrosion coverage ratios and depths and the removal rate of corrosion products inside the corrosion pits. For MgZnCa plates, an increase of FISS results in an increased pitting factor but saturates at an FISS of ∼0.15Pa. For AZ31 stents, the volume loss ratio (31%) at 0.056Pa was nearly twice that (17%) at 0Pa before and after corrosion. Flow direction has a significant impact on corrosion behavior as more severe pitting and erosion corrosion was observed on the back ends of the MgZnCa plates, and the corrosion product layer facing the flow direction peeled off from the AZ31 stent struts. This study demonstrates that flow-induced corrosion needs be understood so that Mg-based stents in vascular environments can be effectively designed.

  16. 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.

  17. Inappropriateness in biliary stenting

    Directory of Open Access Journals (Sweden)

    Giuseppe Chesi

    2013-10-01

    Full Text Available Starting from a real case of a 69-year old patient affected by cholangiocarcinoma, we intend to discuss the accuracy and appropriateness of the diagnostic and therapeutic procedures adopted. This case shows in particular that a more accurate preoperative staging could probably avoid the patient unnecessary laparotomy. According to the indications in the medical literature, this patient could possibly benefit from chemotherapy, but a chemoembolization of liver metastases was performed. However in the literature no available evidence suggests that this treatment would be beneficial in this kind of clinical picture. Eventually, when the disease was already at an advanced stage and worsened due to a necrosis of the left hepatic lobe and a cholangitic infection, a repositioning of the stent on the stent was performed, despite in the literature the life expectancy cut-off for this procedure is at least 6 months. We also discuss the communication between the physician, the patient and the family, which was probably based on overly optimistic and unrealistic expectations. This led to a number of surgical procedures, which were not certainly helpful and indeed were probably even harmful for this patient. In addition, these procedures caused unnecessary costs borne by the healthcare system. In conclusion, we advocate that discussion and self-assessment must be always promoted, so that the healthcare professionals can review the process and the outcome of their treatment as well as their behavior to understand if it could have been more appropriate to offer actual benefits to the patients in terms of better quality of life and longer life expectancy.

  18. 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).

  19. 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.

  20. The preliminary studies on prevention of TIPSS shunt stenosis with 103pd stents

    Institute of Scientific and Technical Information of China (English)

    GAO Qin-Yi; ZHANG Xi-Tong; SHU Qiang; LAN Xiao-LI; LU Xiang-Dong; LI Ya-Ming; PEI Zhu-Guo

    2004-01-01

    To evaluate the role about prevention of shunt stenosis after transjugular intrahepatic portosystemic stent shunt (TIPSS) by 103pd stents, 103pd stents and general stents are placed respectively in 18 healthy swines after TIPSS.Angiography, pathological dissection and inspection of lumen area by light microscope are made respectively in the two groups at 4 and 8 weeks after TIPSS. Portal angiography showed that stenosis occured in 2 cases of the radiation group and 3 cases in the control group at 4 weeks. Occlusion was found in all of the radiation group and part stenosis appeared in 2 cases of the radiation group and 3 cases in control group at 4 weeks. Occlusion existed in all of the radiation group and part stenosis appeared in the control group at 8 weeks. Thickness of vascular wall of hepatic vein segment in scope of stents is (3.64±1.01) mm for the radiation group (12.95MBq) and (2.24±1.02) mm for the control group. Difference between two groups is evidenced (p<0.05). 9.25~12.95MBq 103pd stents can not prevent stenosis after TIPSS.

  1. 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.

  2. 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)

  3. 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.

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

    Science.gov (United States)

    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, 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

  5. 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.

  6. 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

    of death (HR=2.71 [95% CI: 1.72-4.27]) compared to cases without stent thrombosis. In-stent restenosis had no substantial impact (HR=1.17 [95% CI: 0.79-1.75]). However, in-stent restenosis presenting as non-ST-segment elevation myocardial infarction (NSTEMI) was associated with a greater mortality risk...

  7. Local Angiopeptin Delivery Using Coated Stents Reduces Neointimal Proliferation in Overstretched Porcine Coronary Arteries.

    Science.gov (United States)

    De Scheerder I; Wilczek; Van Dorpe J; Verbeken; Cathapermal; Wang; Desmet; Schacht; Foegh; De Geest H; Piessens

    1996-06-01

    BACKGROUND: Systemic administration of angiopeptin has been shown to inhibit myointimal thickening after arterial injury in several animal species. METHODS AND RESULTS: To explore to what extent high and long-lasting local concentrations of angiopeptin influence the healing process after vascular injury, tantalum balloon-expandable stents were first coated with a polymer loaded with angiopeptin 250 µg. Implantation of these stents in porcine coronary arteries resulted in tissue concentrations of 10.7 pg/ml wet weight in the stented arterial segment 24 hours after stent implantation, gradually declining to 2.0 pg/ml wet weight at day 8. Finally, 20 pigs were randomly treated with either an angiopeptin-loaded or a blank-coated stent. At baseline, the angiographic parameters were similar between both groups but, after 6 weeks, the minimal luminal diameter of the stented arterial segment was larger in the angiopeptin-treated pigs when compared to controls (2.20 +/- 0.57 mm vs 1.57 +/- 0.68 mm, p < 0.01) This angiographic finding was confirmed by post-mortem morphometry where the respective lumen area values were 1.00 +/- 0.54 mm2 and 0.43 +/- 0.28 mm2 (p < 0.01). CONCLUSION: Polymer coated stents can be loaded with angiopeptin, which after implantation in porcine right coronary arteries result in high local tissue concentrations gradually declining over more than 8 days. These high local concentrations inhibit myointimal proliferation induced by poly(organo)phosphazene coated overstretched stents.

  8. 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

  9. Controlled delivery of paclitaxel from stent coatings using novel styrene maleic anhydride copolymer formulations.

    Science.gov (United States)

    Richard, Robert; Schwarz, Marlene; Chan, Ken; Teigen, Nikolai; Boden, Mark

    2009-08-01

    The controlled release of paclitaxel (PTx) from stent coatings comprising an elastomeric polymer blended with a styrene maleic anhydride (SMA) copolymer is described. The coated stents were characterized for morphology by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and for drug release using high-performance liquid chromatography (HPLC). Differential scanning calorimetry (DSC) was used to measure the extent of interaction between the PTx and polymers in the formulation. Coronary stents were coated with blends of poly(b-styrene-b-isobutylene-b-styrene) (SIBS) and SMA containing 7% or 14% maleic anhydride (MA) by weight. SEM examination of the stents showed that the coating did not crack or delaminate either before or after stent expansion. Examination of the coating surface via AFM after elution of the drug indicated that PTx resides primarily in the SMA phase and provided information about the mechanism of PTx release. The addition of SMA altered the release profile of PTx from the base elastomer coatings. In addition, the presence of the SMA enabled tunable release of PTx from the elastomeric stent coatings, while preserving mechanical properties. Thermal analysis reveled no shift in the glass transition temperatures for any of the polymers at all drug loadings studied, indicating that the PTx is not miscible with any component of the polymer blend. An in vivo evaluation indicated that biocompatibility and vascular response results for SMA/SIBS-coated stents (without PTx) are similar to results for SIBS-only-coated and bare stainless steel control stents when implanted in the non-injured coronary arteries of common swine for 30 and 90 days.

  10. 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

  11. 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 thrombo...

  12. 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...

  13. Visualization of Stent Lumen in MR Imaging: Relationship with Stent Design and RF Direction

    Directory of Open Access Journals (Sweden)

    Ohno,Seiichiro

    2012-06-01

    Full Text Available 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.

  14. Prospective multi-center registry to evaluate efficacy and safety of the newly developed diamond-like carbon-coated cobalt-chromium coronary stent system.

    Science.gov (United States)

    Ando, Kenji; Ishii, Katsuhisa; Tada, Eiji; Kataoka, Kazuaki; Hirohata, Atsushi; Goto, Kenji; Kobayashi, Katsuyuki; Tsutsui, Hiroshi; Nakahama, Makoto; Nakashima, Hitoshi; Uchikawa, Shinichiroh; Kanda, Junji; Yasuda, Satoshi; Yajima, Junji; Kitabayashi, Hiroshi; Sakurai, Shumpei; Nakanishi, Keita; Inoue, Naoto; Noike, Hirofumi; Hasebe, Terumitsu; Sato, Tetsuya; Yamasaki, Masao; Kimura, Takeshi

    2016-07-22

    The purpose of this multi-center, non-randomized, and open-label clinical trial was to determine the non-inferiority of diamond-like carbon (DLC)-coated cobalt-chromium coronary stent, the MOMO DLC coronary stent, relative to commercially available bare-metal stents (MULTI-LINK VISION(®)). Nineteen centers in Japan participated. The study cohort consisted of 99 patients from 19 Japanese centers with single or double native coronary vessel disease with de novo and restenosis lesions who met the study eligibility criteria. This cohort formed the safety analysis set. The efficacy analysis set consisted of 98 patients (one case was excluded for violating the eligibility criteria). The primary endpoint was target vessel failure (TVF) rate at 9 months after stent placement. Of the 98 efficacy analysis set patients, TVF occurred in 11 patients (11.2 %, 95 % confidence interval 5.7-19.2 %) at 9 months after the index stent implantation. The upper 95 % confidence interval for TVF of the study stent was lower than that previously reported for the commercially available MULTI-LINK VISION(®) (19.6 %), demonstrating non-inferiority of the study stent to MULTI-LINK VISION(®). All the TVF cases were related to target vascular revascularization. None of the cases developed in-stent thrombosis or myocardial infarction. The average in-stent late loss and binary restenosis rate at the 6-month follow-up angiography were 0.69 mm and 10.5 %, respectively, which are lower than the reported values for commercially available bare-metal stents. In conclusion, the current pivotal clinical study evaluating the new MOMO DLC-coated coronary stent suggested its low rates of TVF and angiographic binary restenosis, and small in-stent late loss, although the data were considered preliminary considering the small sample size and single arm study design.

  15. 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

  16. 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.

  17. 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.

  18. "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.

  19. 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.

  20. 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.

  1. [Absorbable coronary stents. New promising technology].

    Science.gov (United States)

    Erbel, Raimund; Böse, Dirk; Haude, Michael; Kordish, Igor; Churzidze, Sofia; Malyar, Nasser; Konorza, Thomas; Sack, Stefan

    2007-06-01

    Coronary stent implantation started in Germany 20 years ago. In the beginning, the progress was very slow and accelerated 10 years later. Meanwhile, coronary stent implantation is a standard procedure in interventional cardiology. From the beginning of permanent stent implantation, research started to provide temporary stenting of coronary arteries, first with catheter-based systems, later with stent-alone technology. Stents were produced from polymers or metal. The first polymer stent implantation failed except the Igaki-Tamai stent in Japan. Newly developed absorbable polymer stents seem to be very promising, as intravascular ultrasound (IVUS) and optical coherence tomography have demonstrated. Temporary metal stents were developed based on iron and magnesium. Currently, the iron stent is tested in peripheral arteries. The absorbable magnesium stent (Biotronik, Berlin, Germany) was tested in peripheral arteries below the knee and meanwhile in the multicenter international PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting with Absorbable Metal Stents) study. The first magnesium stent implantation was performed on July 30, 2004 after extended experimental testing in Essen. The magnesium stent behaved like a bare-metal stent with low recoil of 5-7%. The stent struts were absorbed when tested with IVUS. Stent struts were not visible by fluoroscopy or computed tomography (CT) as well as magnetic resonance imaging (MRI). That means, that the magnesium stent is invisible and therefore CT and MRI can be used for imaging of interventions. Only using micro-CT the stent struts were visible. The absorption process could be demonstrated in a patient 18 days after implantation due to suspected acute coronary syndrome, which was excluded. IVUS showed a nice open lumen. Stent struts were no longer visible, but replaced by tissue indicating the previous stent location. Coronary angiography after 4 months showed an ischemia-driven target lesion

  2. Local Delivery of Antiproliferative Agents via Stents

    Directory of Open Access Journals (Sweden)

    Hyuck Joon Kwon

    2014-03-01

    Full Text Available A stent is a medical device for serving as an internal scaffold to maintain or increase the lumen of a body conduit. Stent placement has become a primary treatment option in coronary artery disease for more than the last two decades. The stenting is also currently used for relieving the symptoms of narrowed lumen of nonvascular organs, such as esophagus, trachea and bronchi, small and large intestines, biliary, and urinary tract. Local delivery of active pharmaceutical agents via the stents can not only enhance healing of certain diseases, but it can also help decrease the potential risk of the stenting procedure to the surrounding tissue. In this review, we focus on reviewing a variety of drug-impregnated stents and local drug delivery systems using the stents.

  3. Prevention of stent thrombosis: challenges and solutions

    Directory of Open Access Journals (Sweden)

    Reejhsinghani R

    2015-01-01

    Full Text Available Risheen Reejhsinghani, Amir S LotfiDivision of Cardiology, Baystate Medical Center, Springfield, MA, USAAbstract: Stent thrombosis is an uncommon but serious complication which carries with it significant mortality and morbidity. This review analyzes the entity of stent thrombosis from a historical and clinical perspective, and chronicles the evolution of this condition through the various generations of stent development, from bare metal to first-generation, second-generation, and third-generation drug-eluting stents. It also delineates the specific risk factors associated with stent thrombosis and comprehensively examines the literature related to each of these risks. Finally, it highlights the preventative strategies that can be garnered from the existing data, and concludes that a multifactorial approach is necessary to combat the occurrence of stent thrombosis, with higher risk groups, such as patients with ST segment elevation myocardial infarction, meriting further research.Keywords: stent thrombosis, preventative strategies, post-procedural myocardial infarction

  4. Endourological Management of Forgotten Encrusted Ureteral Stents

    Directory of Open Access Journals (Sweden)

    Kusuma V. R. Murthy

    2010-08-01

    Full Text Available PURPOSE: To present our experience and discuss the various endourological approaches for treating forgotten encrusted ureteral stents associated with stone formation. MATERIALS AND METHODS: From July 2006 to December 2008, 14 patients (11 men and 3 women with encrusted ureteral stents were analyzed. The average indwelling time of the stent was 4.9 years (range 1 to 12. Plain-film radiography was used to evaluate encrustation, stone burden, and fragmentation of the stents. Intravenous urogram and a Tc99m diethylene triamine penta acetic-acid renogram was used to assess renal function. RESULTS: In seven patients, the entire stent was encrusted, in three patients the encrustation was confined to the ureteral and lower coil part of the stent, two patients had encrustation of the lower coil, and minimal encrustation was observed in two patients. Percutaneous nephrolithotomy was performed in 5 cases and retrograde ureteroscopy with intra-corporeal lithotripsy in 9 patients. Cystolithotripsy was used to manage the distal coil of the encrusted stent in eight patients. Simple cystoscopic removal of the stents with minimal encrustation was carried-out in two cases. Looposcopy and removal of the stent was performed in one patient with an ileal conduit and retained stent. Only one patient required open surgical removal of the stent. Thirteen out of 14 patients were rendered stone and stent free in one session. All except two stents were removed intact and stone analysis of encrustation and calcification revealed calcium oxalate and calcium phosphate in the majority of the cases. CONCLUSION: Endourological management of forgotten encrusted stents is highly successful and often avoids the need for open surgical techniques.

  5. 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

  6. Bilateral brachial pull-through technique for stenting in a patient with stenosis of the vertebral artery origin: technical case report

    Energy Technology Data Exchange (ETDEWEB)

    Kusaka, N.; Nishiguchi, M.; Takayama, K.; Nishiura, T. [National Hospital Organization Iwakuni Clinical Center, Department of Neurosurgery, Iwakuni, Yamaguchi (Japan); Tamiya, T. [Kagawa University of Medicine, Department of Neurological Surgery, Kida-gun, Kagawa (Japan)

    2007-10-15

    Stenting for stenosis of the proximal vertebral artery (VA) is commonly performed via a femoral approach. However, iliofemoral occlusive disease such as arteriosclerosis obliterans sometimes prevents safe transfemoral access. In certain situations where both femoral access and ipsilateral brachial access are difficult because of a concomitant vascular diseases or particular anatomic setting, a contralateral brachial approach using the brachiobrachial pull-through technique may allow efficient and accurate stenting. A case of VA origin symptomatic stenosis successfully treated with stenting using the new pull-through technique from the contralateral brachial artery to the brachial artery on the affected side is described. (orig.)

  7. 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.

  8. Clinical experience in coronary stenting with the Vivant Z Stent.

    Science.gov (United States)

    Chee, K H; Siaw, F S; Chan, C G; Chong, W P; Imran, Z A; Haizal, H K; Azman, W; Tan, K H

    2005-06-01

    This single centre study was designed to demonstrate feasibility, safety and efficacy of the Vivant Z stent (PFM AG, Cologne, Germany). Patients with de novo lesion were recruited. Coronary angioplasty was performed with either direct stenting or after balloon predilatation. Repeated angiogram was performed 6 months later or earlier if clinically indicated. Between January to June 2003, a total of 50 patients were recruited (mean age 55.8 +/- 9 years). A total of 52 lesions were stented successfully. Mean reference diameter was 2.77 mm (+/-0.59 SD, range 2.05-4.39 mm) with mean target lesion stenosis of 65.5% (+/-11.6 SD, range 50.1-93.3%). Forty-six lesions (88.5%) were American College of Cardiologist/American Heart Association class B/C types. Direct stenting was performed in 18 (34.6%) lesions. Mean stent diameter was 3.18 mm (+/-0.41 SD, range 2.5-4 mm), and mean stent length was 14.86 mm (+/-2.72 SD, range 9-18 mm). The procedure was complicated in only one case which involved the loss of side branch with no clinical sequelae. All treated lesions achieved Thrombolysis In Myocardial Infarction 3 flow. Mean residual diameter stenosis was 12.2% (+/-7.55 SD, range 0-22.6%) with acute gain of 1.72 mm (+/-0.50 SD, range 0.5-2.8). At 6 months, there was no major adverse cardiovascular event. Repeated angiography after 6 months showed a restenosis rate of 17% (defined as >50% diameter restenosis). Mean late loss was 0.96 mm (+/-0.48 SD) with loss index of 0.61 (+/-0.38 SD). The restenosis rate of those lesions less than 3.0 mm in diameter was 22.2% compared with 6.25% in those lesions more than 3.0 mm in diameter. The Vivant Z stent was shown to be safe and efficacious with low restenosis rate in de novo coronary artery lesion.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. MR Angiography of Peripheral Arterial Stents: In Vitro Evaluation of 22 Different Stent Types

    Directory of Open Access Journals (Sweden)

    Matthias C. Burg

    2011-01-01

    Full Text Available Purpose. To evaluate stent lumen visibility of a large sample of different peripheral arterial (iliac, renal, carotid stents using magnetic resonance angiography in vitro. Materials and Methods. 21 different stents and one stentgraft (10 nitinol, 7 316L, 2 tantalum, 1 cobalt superalloy, 1 PET + cobalt superalloy, and 1 platinum alloy were examined in a vessel phantom (vessel diameters ranging from 5 to 13 mm filled with a solution of Gd-DTPA. Stents were imaged at 1.5 Tesla using a T1-weighted 3D spoiled gradient-echo sequence. Image analysis was performed measuring three categories: Signal intensity in the stent lumen, lumen visibility of the stented lumen, and homogeneity of the stented lumen. The results were classified using a 3-point scale (good, intermediate, and poor results. Results. 7 stents showed good MR lumen visibility (4x nitinol, 2x tantalum, and 1x cobalt superalloy. 9 stents showed intermediate results (5x nitinol, 2x 316L, 1x PET + cobalt superalloy, and 1x platinum alloy and 6 stents showed poor results (1x nitinol, and 5x 316L. Conclusion. Stent lumen visibility varies depending on the stent material and type. Some products show good lumen visibility which may allow the detection of stenoses inside the lumen, while other products cause artifacts which prevent reliable evaluation of the stent lumen with this technique.

  14. Magnesium used in bioabsorbable stents controls smooth muscle cell proliferation and stimulates endothelial cells in vitro.

    Science.gov (United States)

    Sternberg, Katrin; Gratz, Matthias; Koeck, Kathleen; Mostertz, Joerg; Begunk, Robert; Loebler, Marian; Semmling, Beatrice; Seidlitz, Anne; Hildebrandt, Petra; Homuth, Georg; Grabow, Niels; Tuemmler, Conny; Weitschies, Werner; Schmitz, Klaus-Peter; Kroemer, Heyo K

    2012-01-01

    Magnesium-based bioabsorbable cardiovascular stents have been developed to overcome limitations of permanent metallic stents, such as late stent thrombosis. During stent degradation, endothelial and smooth muscle cells will be exposed to locally high magnesium concentrations with yet unknown physiological consequences. Here, we investigated the effects of elevated magnesium concentrations on human coronary artery endothelial and smooth muscle cell (HCAEC, HCASMC) growth and gene expression. In the course of 24 h after incubation with magnesium chloride solutions (1 or 10 mM) intracellular magnesium level in HCASMC raised from 0.55 ± 0.25 mM (1 mM) to 1.38 ± 0.95 mM (10 mM), while no increase was detected in HCAEC. Accordingly, a DNA microarray-based study identified 69 magnesium regulated transcripts in HCAEC, but 2172 magnesium regulated transcripts in HCASMC. Notably, a significant regulation of various growth factors and extracellular matrix components was observed. In contrast, viability and proliferation of HCAEC were increased at concentrations of up to 25 mM magnesium chloride, while in HCASMC viability and proliferation appeared to be unaffected. Taken together, our data indicate that magnesium halts smooth muscle cell proliferation and stimulates endothelial cell proliferation, which might translate into a beneficial effect in the setting of stent associated vascular injury.

  15. 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.

  16. On the heating of inductively coupled resonators (stents) during MRI examinations.

    Science.gov (United States)

    Busch, Martin; Vollmann, Wolfgang; Bertsch, Thomas; Wetzler, Rainer; Bornstedt, Axel; Schnackenburg, Bernhard; Schnorr, Jörg; Kivelitz, Dietmar; Taupitz, Matthias; Grönemeyer, Dietrich

    2005-10-01

    Stents that have been implanted to preserve the results of vascular dilatation are frequently affected by in-stent restenosis, which ideally should be followed up by a noninvasive diagnostic modality. Active MRI stents can enable this kind of follow-up, while normal metallic stents can not. The prototype stents investigated in this study were designed as electric resonating circuits without a direct connection to the MR imager, and function as inductively coupled transmit coils. The model of a long solenoid coil is used to describe the additional power loss caused by such resonators. The theoretically estimated temperature increase is verified by measurements for different resonators and discussed for worst-case conditions. The RF power absorption of an active resonator is negligible compared to the total power absorbed during MRI. The local temperature increase observed for prototypes embedded in phantoms is in a range that excludes direct tissue damage. However, ruptures in the conducting structure of a resonator can cause hot spots, which may establish a high local temperature. This hazard can be reduced by designing resonators with a low quality (Q) factor or by setting the circuit slightly off resonance; however, this would lower the nominal amplification for which the resonator was designed.

  17. 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.

  18. [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

  19. 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

  20. 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...

  1. Imaging vascular implants with optical coherence tomography

    Science.gov (United States)

    Barton, Jennifer K.; Dal Ponte, Donny B.; Williams, Stuart K.; Ford, Bridget K.; Descour, Michael R.

    2000-04-01

    Vascular stents and grafts have many proven and promising clinical applications, but also a large number of complications. A focus of current research is the development of biocompatible implants. Evaluation of these devices generally requires a large number of animals due to the need for explanation and histological evaluation of the implant at several time intervals. It would be desirable to use instead a high resolution, in situ assessment method. An in vitro study was performed to determine if OCT could image cell proliferation and thrombus formation on vascular stents and grafts. First, images were taken of explanted stents. The implants were locate din peripheral vessels of a porcine model of atherosclerosis. The images clearly show the vessel response to initial damage, the materials of the implant, extent of intimal cell hyper proliferation, and small platelet aggregates. Next, a tissue engineered graft, which had been sodded with smooth muscle cells and incubated in a bioreactor, was evaluated. Cross-section images showed the pores of the polymer material and the layer of smooth muscle cells beginning to invade the graft material. For comparison, in vitro 20 MHz IVUS images of the same grafts were obtained. A catheter was designed for intravascular imaging. The 2.3 mm diameter catheter contains a fiber with GRIN lens and right angle prism, a monorail guidewire, and a novel positioning wire that can be protruded to push the catheter against the vessel wall, potentially eliminating the need for saline flush. Preliminary in vitro results with this catheter are encouraging.

  2. Carotid artery stent continued expansion days after deployment, without post stent deployment angioplasty

    Directory of Open Access Journals (Sweden)

    Umair Qazi

    2015-10-01

    Full Text Available This is a carotid artery stent (CAS case report, which avoids post-stent deployment angioplasty (Post-SDA, with duplex confirmed continued stent expansion at 1, 3 and 30-day post deployment. This report confirms that self-expanding nitinol stents in the carotid artery may not require Post-SDA. We believe CAS can be performed without Post-SDA, which helps reduce the occurrence of intraoperative hemodynamic depression.

  3. Safety, efficacy and costs associated with direct coronary stenting compared with stenting after predilatation

    Science.gov (United States)

    IJsselmuiden, A.; Serruys, P.W.; Tangelder, G.J.; Slagboom, T.; van der Wieken, R.; Kiemeneij, F.; Laarman, G.J.

    2004-01-01

    Objectives Comparison of the in-hospital success rates, procedural costs and short-term clinical outcomes of direct stenting versus stenting after balloon predilatation. Methods Altogether, 400 patients with angina pectoris and/or myocardial ischaemia due to coronary stenoses in a single native vessel were randomised to either direct stenting or stenting after predilatation. Baseline characteristics were evenly distributed between the two groups. Results Procedural success rates were similar (96.0% direct stenting group vs. 94.5% predilatation) as well as final successful stent implantation (98.3 vs. 97.8%), while the primary success rate of direct stenting alone was 88.3%, p=0.01. In multivariate analysis, angiographic lesion calcification was an independent predictor of unsuccessful direct stenting (odds ratio 7.1, 95% confidence interval 2.8-18.2, p0.15 μg/l, used as a measure of distal embolisation, were similar in both groups (17.8 vs. 17.1%). Rates of major adverse cardiac events at 30 days were 4.5% in the direct stenting group versus 5.5% in the predilated group (ns). Direct stenting was associated with savings in fluoroscopy time, and angiographic contrast agent use, and a reduction in utilisation of angioplasty balloons (0.4 vs. 1.17 balloons per patient, p<0.001). Mean per patient procedural costs associated with direct stenting versus predilatation were €2545±914 versus €2763±842 (p=0.01), despite the implantation of more stents in the directly stented group. Conclusion Compared with a strategy of stenting preceded by balloon predilatation, direct stenting was equally safe and effective, with similar in-hospital and 30-day clinical outcomes, and modest procedural cost-savings. A calcified lesion predicted unsuccessful direct stenting. PMID:25696356

  4. 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.

  5. Review of stents for the carotid artery.

    Science.gov (United States)

    Bosiers, M; Deloose, K; Verbist, J; Peeters, P

    2006-04-01

    The individual characteristics of a stent may make it an attractive choice in some circumstances, but render it a less desirable option in others. The applicability depends primarily on the arterial anatomy and the specific details of the lesion being treated. A careful assessment by the interventionalist is required to select the proper type of stent that is of appropriate size. Certainly, personal preferences and familiarity with a specific device may legitimately influence the decision to choose one stent over another. Finally, stent design can play a role in the selection procedure. Although carotid stents are often functionally equivalent in the clinical setting and have been used successfully to treat a wide variety of lesions, a basic knowledge of stent geometry can contribute to make up your mind in certain carotid cases.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Removal of retrievable self-expandable urethral stents: experience in 58 stents

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Ji Hoon; Song, Ho-Young; Kim, Jin Hyoung; Ko, Heung-Kyu; Kim, Yong Jae; Woo, Chul-Woong; Kim, Tae-Hyung; Ko, Gi-Young; Yoon, Hyun-Ki; Sung, Kyu-Bo [Asan Medical Center, Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Seoul (Korea); Park, Hyungkeun [Asan Medical Center, Department of Urology, University of Ulsan College of Medicine, Seoul (Korea)

    2006-09-15

    The purpose of this study was to retrospectively evaluate the safety and efficacy of removing retrievable self-expandable urethral stents using a retrieval hook wire. Under fluoroscopic guidance, the removal of 58 polyurethane or PTFE (polytetrafluoroethylene)-covered stents was attempted in 33 patients using a retrieval hook wire. Indications for removal were elective removal (n=21), stent migration (n=19), formation of tissue hyperplasia around or inside of the stent (n=14), stent deformity (n=3), and severe pain (n=1). The mean time the stents remained in place was 64.8{+-}42.9 days (range, 1-177 days). Fifty-six (97%) of the 58 stents were successfully removed using the retrieval hook wire despite the following difficulties; hook wire disconnection (n=2), untied drawstrings (n=3), and polyurethane membrane disruption/separation (n=4). The removal procedure using a retrieval hook wire failed in two stents (3%) which had migrated into the urinary bladder. One of the two stents with migration into the urinary bladder was removed using a snare through the cystostomy route. The overall complication rate was 14% (seven hematuria cases and one urethral tear case), and all were minor and spontaneously resolved without further treatment. In conclusion, removal of retrievable urethral stents using a retrieval hook wire was safe and effective despite some technical difficulties. It is a useful method for allowing temporary stent placement and solving various complications of stent use. (orig.)

  11. In vitro, time-resolved PIV comparison of the effect of stent design on wall shear stress.

    Science.gov (United States)

    Charonko, John; Karri, Satyaprakash; Schmieg, Jaime; Prabhu, Santosh; Vlachos, Pavlos

    2009-07-01

    The effect of stent design on wall shear stress (WSS) and oscillatory shear index (OSI) was studied in vitro using time-resolved digital particle image velocimetry (DPIV). Four drug-eluting stents [XIENCE V (Abbott Vascular), TAXUS Liberté (Boston Scientific), Endeavor (Medtronic), and Cypher (J&J Cordis)] and a bare-metal stent [VISION (Abbott Vascular)] were implanted into compliant vessel models, and the flow was measured in physiologically accurate coronary conditions featuring reversal and realistic offsets between pressure and flowrate. DPIV measurements were made at three locations under two different flow rates (resting: Re = 160, f = 70 bpm and exercise: Re = 300, f = 120 bpm). It was observed that design substantially affected the WSS experienced at the vessel walls. Averaged values between struts ranged from 2.05 dynes/cm(2) (Cypher) to 8.52 dynes/cm(2) (XIENCE V) in resting conditions, and from 3.72 dynes/cm(2) (Cypher) to 14.66 dynes/cm(2) (VISION) for the exercise state. Within the stent, the WSS dropped and the OSI increased immediately distal to each strut. In addition, an inverse correlation between average WSS and OSI existed. Comparisons with recently published results from animal studies show strong correlation between the measured WSS and observed endothelial cell coverage. These results suggest the importance of stent design on the WSS experienced by endothelial cells in coronary arteries.

  12. 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.

  13. 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.

  14. 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.

  15. Curcumin Attenuates Rapamycin-induced Cell Injury of Vascular Endothelial Cells.

    Science.gov (United States)

    Guo, Ning; Chen, Fangyuan; Zhou, Juan; Fang, Yuan; Li, Hongbing; Luo, Yongbai; Zhang, Yong

    2015-10-01

    Although drug-eluting stents (DES) effectively improve the clinical efficacy of percutaneous coronary intervention, a high risk of late stent thrombosis and in-stent restenosis also exists after DES implantation. Anti-smooth muscle proliferation drugs, such as rapamycin, coating stents, not only inhibit the growth of vascular smooth muscle cells but also inhibit vascular endothelial cells and delay the reendothelialization. Therefore, the development of an ideal agent that protects vascular endothelial cells from rapamycin-eluting stents is of great importance for the next generation of DES. In this study, we demonstrated that rapamycin significantly inhibited the growth of rat aortic endothelial cells in both dose- and time-dependent manner in vitro. Cell apoptosis was increased and migration was decreased by rapamycin treatments in rat aortic endothelial cells in vitro. Surprisingly, treatment with curcumin, an active ingredient of turmeric, significantly reversed these detrimental effects of rapamycin. Moreover, curcumin increased the expression of vascular nitric oxide synthases (eNOS), which was decreased by rapamycin. Furthermore, caveolin-1, the inhibitor of eNOS, was decreased by curcumin. Knockdown of eNOS by small interfering RNA significantly abrogated the protective effects of curcumin. Taken together, our results suggest that curcumin antagonizes the detrimental effect of rapamycin on aortic endothelial cells in vitro through upregulating eNOS. Therefore, curcumin is a promising combined agent for the rescue of DES-induced reendothelialization delay.

  16. Nitinol stent design - understanding axial buckling.

    Science.gov (United States)

    McGrath, D J; O'Brien, B; Bruzzi, M; McHugh, P E

    2014-12-01

    Nitinol׳s superelastic properties permit self-expanding stents to be crimped without plastic deformation, but its nonlinear properties can contribute towards stent buckling. This study investigates the axial buckling of a prototype tracheobronchial nitinol stent design during crimping, with the objective of eliminating buckling from the design. To capture the stent buckling mechanism a computational model of a radial force test is simulated, where small geometric defects are introduced to remove symmetry and allow buckling to occur. With the buckling mechanism ascertained, a sensitivity study is carried out to examine the effect that the transitional plateau region of the nitinol loading curve has on stent stability. Results of this analysis are then used to redesign the stent and remove buckling. It is found that the transitional plateau region can have a significant effect on the stability of a stent during crimping, and by reducing the amount of transitional material within the stent hinges during loading the stability of a nitinol stent can be increased.

  17. 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.

  18. Novel stents for the prevention of restenosis.

    Science.gov (United States)

    McKenna, C J; Holmes, D R; Schwartz, R S

    1997-10-01

    Since the introduction of Interventional Cardiology in 1976, there has been rapid expansion both in its clinical application and the tools of the trade. This growth was accelerated with the introduction of the intra-coronary stent in 1987. The demonstration that stents may reduce the incidence of restenosis after percutaneous coronary revascularization has further stimulated the search for the perfect endovascular prosthesis. By creating a hybrid stent, incorporating natural coatings and local drug delivery in the design, it is hoped that the complications associated with stent thrombosis and restenosis can be eradicated. (Trends Cardiovasc Med 1997;7:245-249). © 1997, Elsevier Science Inc.

  19. Stent Fracture: Case Report and Literature Review

    OpenAIRE

    Lousinha, A; Fiarresga, A; Cardona, L.; Lopes, JP; Lopes, A.; Cacela, D; L. Sousa; Patrício, L; Bernardes, L; Cruz Ferreira, R

    2011-01-01

    Apresentamos o caso de um doente, previamente submetido a angioplastia coronária com um stent revestido com fármaco, com enfarte agudo do miocárdio (EAM) provocado por trombose tardia do stent, tendo sido detectada fractura do mesmo. Este caso vem reforçar o reconhecimento crescente da fractura como potencial mecanismo para a trombose tardia de stent, na era dos stents revestidos com fármaco. A propósito deste caso clínico, apresentamos uma revisão da liter...

  20. 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

  1. 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...

  2. 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%.

  3. 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.

  4. vascular hemiplegia

    OpenAIRE

    Voto Bernales, Jorge; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú

    2014-01-01

    The vascular hemiplegia is the functional disorder of a lateral half of the body produced by alterations of cerebral vessels. Should review the concepts of this common condition, with the dual aim of expanding its nosographic value and considering the hemiplegic patient as worthy of the highest professional care La hemiplejia vascular, es el trastorno funcional de una mitad lateral del cuerpo producido por alteraciones de los vasos cerebrales. Conviene revisar los conceptos sobre esta frec...

  5. 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.

  6. 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.

  7. Compliance Study of Endovascular Stent Grafts Incorporated with Polyester and Polyurethane Graft Materials in both Stented and Unstented Zones

    Directory of Open Access Journals (Sweden)

    Ying Guan

    2016-08-01

    Full Text Available Compliance mismatch between stent graft and host artery may induce complications and blood flow disorders. However, few studies have been reported on stent graft compliance. This study aims to explore the deformation and compliance of stent graft in stented and unstented zones under three pressure ranges. Compliance of two stent grafts incorporated with polyurethane graft (nitinol-PU and polyester graft (nitinol-PET materials respectively were tested; the stents used in the two stent grafts were identical. For the circumferential deformation of the stent grafts under each pressure range, the nitinol-PET stent graft was uniform in both zones. The nitinol-PU stent graft was circumferentially uniform in the stented zone, however, it was nonuniform in the unstented zone. The compliance of the PU graft material was 15 times higher than that of the PET graft. No significant difference in compliance was observed between stented and unstented zones of the nitinol-PET stent graft regardless of the applied pressure range. However, for the nitinol-PU stent graft, compliance of the unstented PU region was approximately twice that of the stented region; thus, compliance along the length of the nitinol-PU stent graft was not constant and different from that of the nitinol-PET stent graft.

  8. 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.

  9. [Edge effect and late thrombosis -- inevitable complications of vascular brachytherapy?].

    Science.gov (United States)

    Schiele, T M; Staber, L; Kantlehner, R; Pöllinger, B; Dühmke, E; Theisen, K; Klauss, V

    2002-11-01

    Restenosis is the limiting entity after percutaneous coronary angioplasty. Vascular brachytherapy for the treatment of in-stent restenosis has been shown to reduce the repeat restenosis rate and the incidence of major adverse events in several randomized trials. Besides the beneficial effects, brachytherapy yielded some unwanted side effects. The development of new stenoses at the edges of the target lesion treated with radiation is termed edge effect. It occurs after afterloading brachytherapy as well as after implantation of radioactive stents. It is characterized by extensive intimal hyperplasia and negative remodeling. As contributing factors the axial dose fall-off, inherent to all radioactive sources, and the application of vessel wall trauma by angioplasty have been identified. The combination of both factors, by insufficient overlap of the radiation length over the injured vessel segment, has been referred to as geographic miss. It has been shown to be associated with a very high incidence of the edge effect. Avoidance of geographic miss is strongly recommended in vascular brachytherapy procedures. Late thrombosis after vascular brachytherapy is of multifactorial origin. It comprises platelet recruitment, fibrin deposition, disturbed vasomotion, non-healing dissection and stent malapposition predisposing to turbulent blood flow. The strongest predictors for late thrombosis are premature discontinuation of antiplatelet therapy and implantation of new stents during the brachytherapy procedure. With a consequent and prolonged antiplatelet therapy, the incidence of late thrombosis has been reduced to placebo levels. Edge effect and late thrombosis represent unwanted side effects of vascular brachytherapy. By means of a thorough treatment planning and prolonged antiplatelet therapy their incidences can be largely reduced. With regard to the very favorable net effect, they do not constitute relevant limitations of vascular brachytherapy.

  10. Coronary artery stent geometry and in-stent contrast attenuation with 64-slice computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Schepis, Tiziano; Koepfli, Pascal; Gaemperli, Oliver; Eberli, Franz R.; Luescher, Thomas F. [University Hospital Zurich, Cardiovascular Center, Zurich (Switzerland); Leschka, Sebastian; Desbiolles, Lotus; Husmann, Lars; Wildermuth, Simon; Marincek, Borut; Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic Radiology, Zurich (Switzerland); Kaufmann, Philipp A. [University Hospital Zurich, Cardiovascular Center, Zurich (Switzerland); Zurich Center for Integrative Human Physiology, Zurich (Switzerland)

    2007-06-15

    We aimed at assessing stent geometry and in-stent contrast attenuation with 64-slice CT in patients with various coronary stents. Twenty-nine patients (mean age 60 {+-} 11 years; 24 men) with 50 stents underwent CT within 2 weeks after stent placement. Mean in-stent luminal diameter and reference vessel diameter proximal and distal to the stent were assessed with CT, and compared to quantitative coronary angiography (QCA). Stent length was also compared to the manufacturer's values. Images were reconstructed using a medium-smooth (B30f) and sharp (B46f) kernel. All 50 stents could be visualized with CT. Mean in-stent luminal diameter was systematically underestimated with CT compared to QCA (1.60 {+-} 0.39 mm versus 2.49 {+-} 0.45 mm; P < 0.0001), resulting in a modest correlation of QCA versus CT (r = 0.49; P < 0.0001). Stent length as given by the manufacturer was 18.2 {+-} 6.2 mm, correlating well with CT (18.5 {+-} 5.7 mm; r = 0.95; P < 0.0001) and QCA (17.4 {+-} 5.6 mm; r = 0.87; P < 0.0001). Proximal and distal reference vessel diameters were similar with CT and QCA (P = 0.06 and P = 0.03). B46f kernel images showed higher image noise (P < 0.05) and lower in-stent CT attenuation values (P < 0.001) than images reconstructed with the B30f kernel. 64-slice CT allows measurement of coronary artery in-stent density, and significantly underestimates the true in-stent diameter compared to QCA. (orig.)

  11. Percutaneous transradial artery approach for coronary Palmaz-Schatz stent implantation.

    Science.gov (United States)

    Kiemeneij, F; Laarman, G J

    1994-07-01

    The purpose of this study was to evaluate feasibility, safety, and efficacy of implantation of unsheathed Palmaz-Schatz coronary stents via the radial artery. Anticoagulation after coronary stenting has the hazard of vascular complications if large-bore guiding catheters are introduced via the femoral artery. Such complications have serious local sequelae, are associated with suboptimal anticoagulation, and prolong hospitalization. By combining 6F guiding catheters and low-profile dilatation catheters with bare Palmaz-Schatz stents, smaller vessels such as the radial artery can be selected as the entry site. It is postulated that no major puncture site-related complications occur because hemostasis is easily achieved and no veins and nerves are near the radial artery. With double blood supply to the hand, radial artery occlusion is well tolerated. Twenty-five bare Palmaz-Schatz stents were implanted via the radial artery through 6F guiding catheters in 20 consecutive patients for venous bypass graft stenosis (n = 9; 45%), native coronary artery restenosis (n = 7; 35%) and suboptimal transradial artery PTCA (n = 4; 20%). Immediately after stent implantation and assessment of the result by means of computerized quantitative coronary analysis, the arterial sheath was withdrawn followed by intense anticoagulation and free ambulation of the patient. Radial artery function and anatomy were assessed by two-dimensional and Doppler ultrasound examination. Lesions (n = 24) were of type A (n = 13; 54%), B (n = 6; 25%) and C (n = 5; 21%). The reference diameter of the stented segments was 3.2 +/- 0.5 mm (2.2 to 4.2 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

  12. 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.

  13. 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...

  14. 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.

  15. 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

  16. Preoperative optimization of the vascular surgery patient

    Directory of Open Access Journals (Sweden)

    Zhan HT

    2015-07-01

    Full Text Available Henry T Zhan,1 Seth T Purcell,1,2 Ruth L Bush1 1Texas A&M Health Science Center College of Medicine, Bryan, 2Baylor Scott and White, Temple, TX, USA Abstract: It is well known that patients who suffer from peripheral (noncardiac vascular disease often have coexisting atherosclerotic diseases of the heart. This may leave the patients susceptible to major adverse cardiac events, including death, myocardial infarction, unstable angina, and pulmonary edema, during the perioperative time period, in addition to the many other complications they may sustain as they undergo vascular surgery procedures, regardless of whether the procedure is performed as an open or endovascular modality. As these patients are at particularly high risk, up to 16% in published studies, for postoperative cardiac complications, many proposals and algorithms for perioperative optimization have been suggested and studied in the literature. Moreover, in patients with recent coronary stents, the risk of noncardiac surgery on adverse cardiac events is incremental in the first 6 months following stent implantation. Just as postoperative management of patients is vital to the outcome of a patient, preoperative assessment and optimization may reduce, and possibly completely alleviate, the risks of major postoperative complications, as well as assist in the decision-making process regarding the appropriate surgical and anesthetic management. This review article addresses several tools and therapies that treating physicians may employ to medically optimize a patient before they undergo noncardiac vascular surgery. Keywords: perioperative care, intraoperative care, medical management, risk evaluation/stratification, medical treatment

  17. 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......) in patients with STEMI. METHODS AND RESULTS: ABSORB-STEMI TROFI II was a multicentre, single-blind, non-inferiority, randomized controlled trial. Patients with STEMI who underwent primary percutaneous coronary intervention were randomly allocated 1:1 to treatment with the Absorb or EES. The primary endpoint...

  18. 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

  19. Mesenchymal stem cell seeding promotes reendothelialization of the endovascular stent.

    Science.gov (United States)

    Wu, Xue; Wang, Guixue; Tang, Chaojun; Zhang, Dechuan; Li, Zhenggong; Du, Dingyuan; Zhang, Zhengcai

    2011-09-01

    This study is designed to make a novel cell seeding stent and to evaluate reendothelialization and anti-restenosis after the stent implantation. In comparison with cell seeding stents utilized in previous studies, Mesenchymal stem cells (MSCs) have advantages on promoting of issue repair. Thus it was employed to improve the reendothelialization effects of endovascular stent in present work. MSCs were isolated by density gradient centrifugation and determined as CD29(+) CD44(+) CD34(-) cells by immunofluorescence and immunocytochemistry; gluten and polylysine coated stents were prepared by ultrasonic atomization spray, and MSCs seeded stents were made through rotation culture according to the optimized conditions that were determined in previous studies. The results from animal experiments, in which male New Zealand white rabbits were used, show that the reendothelialization of MSCs coated stents can be completed within one month; in comparison with 316L stainless steel stents (316L SS stents) and gluten and polylysine coated stents, the intimal hyperplasia and in-stent restenosis are significantly inhibited by MSCs coated stents. Endovascular stent seeded with MSCs promotes reendothelialization and inhibits the intimal hyperplasia and in-stent restenosis compared with the 316L SS stents and the gluten and polylysine coated stents.

  20. 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.)

  1. Atrial septal stenting - How I do it?

    Directory of Open Access Journals (Sweden)

    Kothandam Sivakumar

    2015-01-01

    Full Text Available A wide atrial communication is important to maintain hemodynamics in certain forms of congenital and acquired heart defects. In comparison to balloon septostomy or blade septostomy, atrial septal stenting provides a controlled, predictable, and long-lasting atrial communication. It often needs a prior Brockenbrough needle septal puncture to obtain a stable stent position. A stent deployed across a previously dilated and stretched oval foramen or tunnel form of oval foramen carries higher risk of embolization. This review provides technical tips to achieve a safe atrial septal stenting. Even though this is a "How to do it article," an initial discussion about the indications for atrial septal stenting is vital as the resultant size of the atrial septal communication should be tailored for each indication.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Updates on the use of ureteral stents: focus on the Resonance® stent

    Directory of Open Access Journals (Sweden)

    Thomas MT Turk

    2010-12-01

    Full Text Available Manoj V Rao, Anthony J Polcari, Thomas MT TurkDepartment of Urology, Loyola University Medical Center, Maywood, IL, USAAbstract: The Resonance® metallic ureteral stent is one of the latest additions to the urologist’s armamentarium in managing ureteral obstruction. One advantage of this stent over traditional polymer-based stents is resistance to encrustation with stone material, which allows longer dwell times and less frequent exchange procedures. Although exchanging a metallic stent is slightly more complicated than exchanging a polymer stent, the fluoroscopic techniques required are familiar to most urologists. The Resonance stent is also more resistant to compression by external forces, potentially allowing greater applicability in patients with metastatic cancer. Furthermore, the use of this stent in patients with benign ureteral obstruction is shown to be associated with significant cost reduction. Clinical studies on the use of this stent are accumulating and the results are mixed, although Level 1 evidence is lacking. In this article we present a comprehensive review of the available literature on the Resonance metallic ureteral stent.Keywords: resonance, metallic, ureteral, stent, obstruction

  8. 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.

  9. 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...

  10. MR safety and imaging of neuroform stents at 3T.

    Science.gov (United States)

    Nehra, Arvind; Moran, Christopher J; Cross, Dewitte T; Derdeyn, Colin P

    2004-10-01

    The Neuroform stent is a self-expanding nitinol stent designed for use in wide-necked intracranial aneurysms. Heating and imaging artifacts were evaluated by using a porcine carotid artery aneurysm model in a 3T MR system. A suspended Neuroform stent was tested for deflection. No heating was measured, and no evidence of deflection of the stent was found. Imaging artifacts were minimal. MR imaging in patients with Neuroform stent-treated aneurysms is safe and feasible.

  11. 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.

  12. Vascular Disease Foundation

    Science.gov (United States)

    ... Contact Us Vascular Disease What is Vascular Disease? Education and Awareness Vascular Diseases Abdominal Aortic Aneurysm Aortic Dissection Arteriovenous Malformation Atherosclerosis Buerger's Disease Carotid Artery Disease ...

  13. What Is Vascular Disease?

    Science.gov (United States)

    ... Contact Us Vascular Disease What is Vascular Disease? Education and Awareness Vascular Diseases Abdominal Aortic Aneurysm Aortic Dissection Arteriovenous Malformation Atherosclerosis Buerger's Disease Carotid Artery Disease ...

  14. In vitro hemocompatibility studies of (poly(L-lactide) and poly(L-lactide-co-glycolide) as materials for bioresorbable stents manufacture.

    Science.gov (United States)

    Szymonowicz, Maria; Rybak, Zbigniew; Witkiewicz, Wojciech; Pezowicz, Celina; Filipiak, Jarosław

    2014-01-01

    Vascular stents are one of the most popular modern methods of dealing with advanced coronary artery disease. At the same time stents are foreign objects to the body, they can stimulate proliferation of vascular endothelium and finally lead to restenosis. Biomaterials designed for temporary and permanent contact with an organism should be biologically inert especially in the case of contact with liquid tissue such as blood. The study aims to assess the impact of resorbable polymers: poly(L-lactide) (PLLA) and poly(L-lactide-co-glycolide) (PLGA), intended for the construction of bioresorbable stents, on activation of coagulation, haemolysis, and morphology of blood cells. The test results showed that in terms of haemolytic activity the samples selected from PLLA and PLGA, shaped by compression pressure followed by laser cutting, do not cause changes in the structural elements of blood and meet the biocompatibility requirements for materials intended for use in the circulatory system.

  15. 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.

  16. Stent graft implantation in an aortic pseudoaneurysm associated with a fractured Cheatham-Platinum stent in aortic coarctation.

    Science.gov (United States)

    Kuhelj, Dimitrij; Berden, Pavel; Podnar, Tomaž

    2016-03-01

    We report a case of aortic pseudoaneurysm associated with a fractured bare Cheatham-Platinum stent following stenting for aortic coarctation. These complications were recognised 6 years after the implantation procedure and were successfully managed by percutaneous stent graft implantation. Staged approach for stent dilatation might prevent development of aortic pseudoaneurysms. In addition, careful follow-up is warranted after stenting for aortic coarctation, particularly in patients with recognised aortic wall injury.

  17. 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

  18. 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.

  19. 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.

  20. 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.

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

    Science.gov (United States)

    Lee, Cheng-Hung; Lin, Yu-Huang; Chang, Shang-Hung; Tai, Chun-Der; Liu, Shih-Jung; Chu, Yen; Wang, Chao-Jan; Hsu, Ming-Yi; Chang, Hung; Chang, Gwo-Jyh; Hung, Kuo-Chun; Hsieh, Ming-Jer; Lin, Fen-Chiung; Hsieh, I-Chang; Wen, Ming-Shien; Huang, Yenlin

    2014-01-01

    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 highperformance liquid chromatography assay. The experimental results suggest that biodegradable nanofibers release high concentrations of acetylsalicylic acid for three weeks. The in vivo efficacy of local delivery of acetylsalicylic acid in reducing platelet and monocyte adhesion, and the minimum tissue inflammatory reaction caused by the hybrid stents in treating denuded rabbit arteries, are documented. The proposed hybrid stent, with biodegradable acetylsalicylic acid-loaded nanofibers, substantially contributed to local, sustained delivery of drugs to promote re-endothelialization and reduce thrombogenicity in the injured artery. The stents may have potential applications in the local delivery of cardiovascular drugs. Furthermore, the use of hybrid stents with acetylsalicylic acid-loaded nanofibers that have high drug loadings may provide insight into the treatment of patients with high risk of acute stent thromboses.

  2. 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.

  3. 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.

  4. 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...... to improve cardiovascular events compared with BMS beyond 1 year. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NTC00962416....

  5. Trajectory surgical guide stent for implant placement.

    Science.gov (United States)

    Adrian, E D; Ivanhoe, J R; Krantz, W A

    1992-05-01

    This article describes a new implant placement surgical guide that gives both implant location and trajectory to the surgeon. Radiopaque markers are placed on diagnostic dentures and a lateral cephalometric radiograph is made that shows the osseous anatomy at the symphysis and the anterior tooth location. The ideal implant location and trajectory data are transferred to a surgical stent that programs the angle and location of the fixtures at time of surgery. The stent has the additional benefit of acting as an occlusion rim, a mouth prop, and tongue retractor. Use of this stent has resulted in consistently programming the placement of implant fixtures that are prosthodontically ideal.

  6. Efficacy and safety of drug-eluting stent implantation for the treatment of in-stent restenosis occurring within bare-metal stent and drug-eluting stent*

    OpenAIRE

    Ge, Heng; Zhang, Qing; Zhou, Wei; He, Qing; Han, Zhi-hua; He, Ben

    2010-01-01

    Objective: Although drug-eluting stent (DES) implantation is the primary treatment modality for bare-metal stent (BMS) in-stent restenosis (ISR), little is known about the efficacy and safety profile of DES in the treatment of DES-ISR. The goal of this study was to compare the clinical outcomes following DES treatment for BMS-ISR and DES-ISR. Methods: Rates of major adverse cardiac events (MACE) were compared in 97 consecutive patients who underwent DES implantation for the treatment of ISR (...

  7. Paraffin processing of stented arteries using a postfixation dissolution of metallic and polymeric stents.

    Science.gov (United States)

    Fishbein, Ilia; Welch, Tre; Guerrero, David T; Alferiev, Ivan S; Adamo, Richard F; Chorny, Michael; Gupte, Rohit K; Tang, Yanqing; Levy, Robert J

    Studying the morphology of the arterial response to endovascular stent implantation requires embedding the explanted stented artery in rigid materials such as poly(methyl methacrylate) to enable sectioning through both the in situ stent and the arterial wall, thus maintaining the proper anatomic relationships. This is a laborious, time-consuming process. Moreover, the technical quality of stained plastic sections is typically suboptimal and, in some cases, precludes immunohistochemical analysis. Here we describe a novel technique for dissolution of metallic and plastic stents that is compatible with subsequent embedding of "destented" arteries in paraffin, fine sectioning, major staining protocols, and immunohistochemistry.

  8. Endovascular treatment of intrahepatic inferior vena cava obstruction from malignant hepatocellular tumor thrombus utilizing Luminexx self-expanding nitinol stents

    Energy Technology Data Exchange (ETDEWEB)

    Stambo, Glenn W. [Division of Vascular and Interventional Radiology, Department of Radiology, St. Joseph' s Hospital and Medical Center, 4516 North Armenia Avenue, Tampa, FL 33603 (United States)], E-mail: xraydoc2@yahoo.com; Leto, John [Division of Vascular and Interventional Radiology, Department of Radiology, St. Joseph' s Hospital and Medical Center, 3001 W. Dr. Martin Luther King Jr. Blvd., Tampa, FL 33607 (United States); George, Christopher [Department of Hematology and Oncology, St. Joseph' s Hospital and Medical Center, 4301 W. Habana Avenue, Suite 1, Tampa, FL 33607 (United States); Van Epps, Kelly; Woeste, Troy; Berlet, Mathew [Division of Vascular and Interventional Radiology, Department of Radiology, St. Joseph' s Hospital and Medical Center, 4516 North Armenia Avenue, Tampa, FL 33603 (United States)

    2008-05-15

    Inferior vena cava (IVC) obstruction is a well-described clinical entity. Most IVC obstructions from malignant neoplasms are a direct result of tumor compression [Oviedo J, Cerda S. Vascular invasion by hepatocellular carcinoma. Arch Pathol Lab Med 2001;125: 454-5; Furui S, Sawada S, et al. Gianturco stent placement in malignant caval obstruction: analysis of factors for predicting the outcome. Radiology 1995;195:147-52; Fletcher WS, Lakin PC, et al. Results of treatment of inferior vena cava syndrome with expandable metallic stents. Arch Surg 1998;133:935-8]. The symptoms of IVC obstruction include progressive ascites, scrotal edema and lower body edema. These constellations of symptoms are described as IVC syndrome and are devastating to a patient with end-stage cancer. We describe a palliative therapy utilizing Luminexx nitinol self-expanding stents to treat intracaval hepatoma thrombus obstructing the IVC. The procedure is rapidly performed, technically reliable, and has essentially no morbidity or mortality. This procedure can be performed in the interventional radiology suite with excellent results resolving the IVC syndrome soon after placement of the stents. We believe endovascular stenting as an excellent palliative therapy for patients with IVC syndrome and should be the treatment of choice for caval obstructions due to intraluminal tumor thrombus.

  9. Asymmetrical field emitter

    Science.gov (United States)

    Fleming, J.G.; Smith, B.K.

    1995-10-10

    A method is disclosed for providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure. 17 figs.

  10. Development and assessment of 316LVM cardiovascular stents

    Energy Technology Data Exchange (ETDEWEB)

    Raval, Ankur [Research and Development Division, Sahajanand Medical Technologies, Surat 395003 (India)]. E-mail: ankur.med@sahmed.com; Choubey, Animesh [Research and Development Division, Sahajanand Medical Technologies, Surat 395003 (India); Engineer, Chhaya [Research and Development Division, Sahajanand Medical Technologies, Surat 395003 (India); Kothwala, Devesh [Research and Development Division, Sahajanand Medical Technologies, Surat 395003 (India)

    2004-11-25

    One of the most common causes for heart failure is vasoconstriction. The medical procedure for alleviating vasoconstriction, angioplasty, calls for intracoronary stents. And the manufacture of intracoronary stents demands absolutely unmatched precision. Current study investigates CNC controlled pulsed Nd:YAG (neodymium:yttrium aluminium garnet) laser for cutting complex geometry of a stent on 316LVM tubings. It has been shown that surface quality of cardiovascular stents has a significant influence on biocompatibility. Therefore, optimal method and parameters for acid pickling of these slotted tube laser cut stents were explored, as a pretreatment for electropolishing. Pickling was necessary prior to electropolishing for removing the oxide films covering the stent surface. An optimal condition for electrochemical polishing could also be established and it caused a smooth stent surface. Passivation of these electropolished stents was done. Furthermore, materials characterization of stents was performed by means of composition and microstructural analysis.

  11. Mechanical design of an intracranial stent for treating cerebral aneurysms.

    Science.gov (United States)

    Shobayashi, Yasuhiro; Tanoue, Tetsuya; Tateshima, Satoshi; Tanishita, Kazuo

    2010-11-01

    Endovascular treatment of cerebral aneurysms using stents has advanced markedly in recent years. Mechanically, a cerebrovascular stent must be very flexible longitudinally and have low radial stiffness. However, no study has examined the stress distribution and deformation of cerebrovascular stents using the finite element method (FEM) and experiments. Stents can have open- and closed-cell structures, and open-cell stents are used clinically in the cerebrovasculature because of their high flexibility. However, the open-cell structure confers a risk of in-stent stenosis due to protrusion of stent struts into the normal parent artery. Therefore, a flexible stent with a closed-cell structure is required. To design a clinically useful, highly flexible, closed-cell stent, one must examine the mechanical properties of the closed-cell structure. In this study, we investigated the relationship between mesh patterns and the mechanical properties of closed-cell stents. Several mesh patterns were designed and their characteristics were studied using numerical simulation. The results showed that the bending stiffness of a closed-cell stent depends on the geometric configuration of the stent cell. It decreases when the stent cell is stretched in the circumferential direction. Mechanical flexibility equal to an open-cell structure was obtained in a closed-cell structure by varying the geometric configuration of the stent cell.

  12. Endovascular Access for Challenging Anatomies in Peripheral Vascular Interventions.

    Science.gov (United States)

    Vatakencherry, Geogy; Gandhi, Ripal; Molloy, Christopher

    2016-06-01

    Vascular interventionalists continue to expand the scope and breadth of endovascular procedures that we offer to our patients. However, we often have to overcome various anatomical and technical challenges to deliver an endovascular device. This article should give the modern interventionalist an array of technical tips and tricks to enable them to overcome various challenging anatomical features such as vessel tortuosity, vascular calcifications, and increasing abdominal pannus. We also hope to elucidate alternative accesses such as radial access, pedal access, popliteal access, and direct stent access as well as direct aortic access.

  13. 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.

  14. Intracoronary brachytherapy in the treatment of in-stent restenosis. Initial experience in Brazil

    Directory of Open Access Journals (Sweden)

    Fábio Sândoli de Brito Jr

    2001-09-01

    Full Text Available Intracoronary brachytherapy using beta or gamma radiation is currently the most efficient type of therapy for preventing the recurrence of coronary in-stent restenosis. Its implementation depends on the interaction among interventionists, radiotherapists, and physicists to assure the safety and quality of the method. The authors report the pioneering experience in Brazil of the treatment of 2 patients with coronary in-stent restenosis, in whom beta radiation was used as part of the international multicenter randomized PREVENT study (Proliferation REduction with Vascular ENergy Trial. The procedures were performed rapidly and did not require significant modifications in the traditional techniques used for conventional angioplasty. Alteration in the radiological protection devices of the hemodynamic laboratory were also not required, showing that intracoronary brachytherapy using beta radiation can be incorporated into the interventional tools of cardiology in our environment.

  15. Nanotextured stainless steel for improved corrosion resistance and biological response in coronary stenting

    Science.gov (United States)

    Mohan, Chandini C.; Prabhath, Anupama; Cherian, Aleena Mary; Vadukumpully, Sajini; Nair, Shantikumar V.; Chennazhi, Krishnaprasad; Menon, Deepthy

    2014-12-01

    Nanosurface engineering of metallic substrates for improved cellular response is a persistent theme in biomaterials research. The need to improve the long term prognosis of commercially available stents has led us to adopt a `polymer-free' approach which is cost effective and industrially scalable. In this study, 316L stainless steel substrates were surface modified by hydrothermal treatment in alkaline pH, with and without the addition of a chromium precursor, to generate a well adherent uniform nanotopography. The modified surfaces showed improved hemocompatibility and augmented endothelialization, while hindering the proliferation of smooth muscle cells. Moreover, they also exhibited superior material properties like corrosion resistance, surface integrity and reduced metal ion leaching. The combination of improved corrosion resistance and selective vascular cell viability provided by nanomodification can be successfully utilized to offer a cell-friendly solution to the inherent limitations pertinent to bare metallic stents.

  16. Vertebral artery origin stenting with buddy wire technique in tortuous subclavian artery

    Energy Technology Data Exchange (ETDEWEB)

    Kizilkilic, Osman [Baskent University Department of Radiology, Adana Teaching and Medical Research Center, 01170 Yuregir-Adana (Turkey)]. E-mail: ebos90@hotmail.com

    2007-01-15

    Catheterization of vessels with severe tortuosity and atherosclerotic changes may represent a technical challenge and is associated with a higher incidence of vascular complications [Putman CM, Chaloupka JC. Use of large-caliber coronary guiding catheters for neurointerventional applications. AJNR Am J Neuroradiol 1996;17:697-704]. Placement of guiding catheter to the tortuous subclavian artery in vertebral artery origin stenting procedure is such a condition with difficulties. In the presence of severe tortuosity of aortic arch and proximal subclavian artery placement of guiding catheter may be difficult and yield poor backup support. We describe a technique that uses a buddy wire to make the guiding catheter stable in its proper position and make possible to perform stenting the vertebral artery origin stenosis.

  17. Comparison of short-term outcomes after carotid artery stenting according to different stent designs

    Science.gov (United States)

    Açar, Göksel; Özkan, Birol; Alıcı, Gökhan; Yazıcıoglu, Mehmet Vefik; Bulut, Mustafa; Kalkan, Mehmet Emin; Demir, Serdar; Acar, Rezzan Deniz; Boztosun, Bilal

    2013-01-01

    Introduction In the developed countries, stroke is the third most common cause of death. There are many data indicating that stents reduce the risk of embolism but there are few publications assessing whether different stent designs can influence the periprocedural complications. Aim To determine the effects of open- and closed-cell stent designs on 1-month results of carotid artery stenting (CAS). Material and methods The study group consisted of 290 consecutive patients (216 men and 74 women, mean age 66.6 ±8.7 years). Neuroprotection with a distal protection device was used in all cases. The patients were divided into two groups: the open-cell stent group (n = 144) and the closed-cell stent group (n = 138). Major adverse cardiac and cerebrovascular events (MACCE) described as myocardial infarction, stroke and death within 1 month were recorded and analysed subsequently. Periprocedural hypotension and transient cerebral ischaemia at 1 month after the CAS procedure were also assessed. Results We treated 290 carotid stenoses and stents were implanted in all patients. Fifteen patients (5.5%) were treated by staged CAS due to bilateral carotid artery disease. The technical success rate was 97.2%. There was no difference in the MACCE and transient cerebral ischaemia rate at 1 month between the two groups (p = 0.44 and p = 0.94, respectively). The incidence of ischaemic stroke was lower in the closed-cell stent group (2.77% vs. 0%; p = 0.04). The periprocedural rate of hypotension was higher in the closed-cell stent group (2.1% vs. 7.2%; p = 0.04). Conclusions Closed-cell stents are associated with a low rate of ischaemic stroke. We think that closed-cell stents may be preferred in patients at high risk of embolism. PMID:24570703

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Sirolimus-eluting dextran and polyglutamic acid hybrid coatings on AZ31 for stent applications

    Science.gov (United States)

    Ma, Jun; Zhao, Nan; Zhu, Donghui

    2016-01-01

    Magnesium (Mg)-based cardiovascular stents are promising candidate as the next generation of novel stents. Clinical studies have revealed encouraging outcomes, but late restenosis and thrombogenesis still largely exist. Blood and vascular biocompatible coatings with drug-eluting features could be the solution to such problems. Objective This study was to investigate the feasibility of a three-layer hybrid coating on Mg alloy AZ31 with sirolimus-eluting feature for cardiovascular stent application. Materials and methods The first and third layers were low molecular weight dextran loaded with sirolimus, and the second layer was polyglutamic acid (PGA) to control sirolimus release. The hybrid coating was verified by scanning electron microscope (SEM). DC polarization and immersion tests were used to evaluate corrosion rate of the materials. Indirect cell viability and cell proliferation tests were performed by culturing cells with extract solutions of AZ31 samples. Blood compatibility was assessed using hemolysis assay. Results Coated samples had an enhanced corrosion resistance than that of uncoated controls, more PGA slower corrosion. Sirolimus had a burst release for the initial ~3 days and then a slower release until reached a plateau. The PGA thickness was able to control the sirolimus release, the thicker of PGA the slower release. The overall cell viability was extract concentration-dependent, and improved by the hybrid coatings. Cell proliferation was correlated to coating thickness and was inhibited by sirolimus. In addition, all coated AZ31 samples were non-hemolytic. Conclusion Results demonstrated that such a three-layer hybrid coating may be useful to improve the vascular biocompatibility of Mg stent materials. PMID:26202889

  3. RNA-Eluting Surfaces for the Modulation of Gene Expression as A Novel Stent Concept

    Directory of Open Access Journals (Sweden)

    Olivia Koenig

    2017-02-01

    Full Text Available Presently, a new era of drug-eluting stents is continuing to improve late adverse effects such as thrombosis after coronary stent implantation in atherosclerotic vessels. The application of gene expression–modulating stents releasing specific small interfering RNAs (siRNAs or messenger RNAs (mRNAs to the vascular wall might have the potential to improve the regeneration of the vessel wall and to inhibit adverse effects as a new promising therapeutic strategy. Different poly (lactic-co-glycolic acid (PLGA resomers for their ability as an siRNA delivery carrier against intercellular adhesion molecule (ICAM-1 with a depot effect were tested. Biodegradability, hemocompatibility, and high cell viability were found in all PLGAs. We generated PLGA coatings with incorporated siRNA that were able to transfect EA.hy926 and human vascular endothelial cells. Transfected EA.hy926 showed significant siICAM-1 knockdown. Furthermore, co-transfection of siRNA and enhanced green fluorescent protein (eGFP mRNA led to the expression of eGFP as well as to the siRNA transfection. Using our PLGA and siRNA multilayers, we reached high transfection efficiencies in EA.hy926 cells until day six and long-lasting transfection until day 20. Our results indicate that siRNA and mRNA nanoparticles incorporated in PLGA films have the potential for the modulation of gene expression after stent implantation to achieve accelerated regeneration of endothelial cells and to reduce the risk of restenosis.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. Drug-eluting stents, restenosis and revascularization.

    Science.gov (United States)

    Ramcharitar, Steve; Gaster, Anne Louise; Daemen, Joost; Serruys, Patrick

    2007-06-01

    Several meta-analyses have demonstrated the superiority of drug-eluting stents (DES) in reducing the incidence of restenosis, target vessel revascularization and target lesion revascularization compared to their predecessor, the bare-metal stent. In comparing Cypher and Taxus stents, the two most recent meta-analyses have given the edge to the Cypher. However, it must be stressed that the superiority of one DES over another remains debatable due to ever changing "real-world data" compared to those attained from randomized trials. The newer sirolimus analogs and selective inhibitors are challenging the old guard in their quest to further limit restenosis. So too are the newer "high-tech" polymers and additionally by using more biodegradable material in the stent's design. Stents aimed at targeting lesions are a new armament in the battle against restenosis and together with combination therapies are exciting key areas to watch. The ideal way to treat a DES in-stent restenosis is still a challenge and hence the impetus is to avoid it from happening in the first place.

  9. 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.

  10. 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.

  11. 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

  12. Technical options for treatment of in-stent restenosis after carotid artery stenting

    NARCIS (Netherlands)

    Pourier, Vanessa E C; de Borst, Gert J.

    2016-01-01

    Objective This review summarizes the available evidence and analyzes the current trends on treatments for carotid in-stent restenosis (ISR) after carotid artery stenting (CAS). Methods An update of a 2010 review of the literature (which included 20 articles) was conducted using PubMed and Embase. Al

  13. Fully biodegradable coronary stents : progress to date.

    Science.gov (United States)

    Ramcharitar, Steve; Serruys, Patrick W

    2008-01-01

    The limitations of currently available metallic drug-eluting stents have renewed interest in biodegradable stents (BDS). Apart from removing the (offending) foreign material that may potentiate a thrombotic event, BDS have the advantage of avoiding 'full metal jackets,' and thus can preclude subsequent coronary surgery. In addition, they do not interfere with the diagnostic evaluation of non-invasive imaging such as cardiac magnetic resonance and CT. There are now several BDS in development or in clinical trials that incorporate a variety of biodegradable polymer technologies. Two broad categories of materials are generally used: those made from organic biopolymers and those made from corrodible metals. However, to date, none of the materials/stents tested have been able to establish a perfect balance between biocompatibility, the kinetics of degradation needed to maintain mechanical strength to limit recoil, and inflammation. However, studies, such as the ABSORB trial with the everolimus eluting poly-L-lactide stent, which demonstrated comparable restenotic rates with bare metallic stents and a low incidence of major adverse cardiac events (MACE) at 12 months of 3.3%, with only one patient having a non-Q-wave myocardial infarction and no target lesion revascularization, suggest that there has been significant progress with respect to the earlier prototypes. The acute recoil observed could potentially be addressed with the polytyrosine REVA stent currently being evaluated in the RESORB trial, which incorporates a novel locking mechanism within its design. Alternative BDS designs include the combination of an antiproliferative drug with endothelial progenitor cell capturing antibodies to facilitate epithelialization and/or dual eluting having, in addition to the antiproliferative drug, polymeric salicyclic acid to limit inflammation. Compared with biodegradable polymers, there are fewer metals used in the manufacture of BDS. The only metal BDS in trials is the

  14. Extent and distribution of in-stent intimal hyperplasia and edge effect in a non-radiation stent population.

    Science.gov (United States)

    Weissman, N J; Wilensky, R L; Tanguay, J F; Bartorelli, A L; Moses, J; Williams, D O; Bailey, S; Martin, J L; Canos, M R; Rudra, H; Popma, J J; Leon, M B; Kaplan, A V; Mintz, G S

    2001-08-01

    Intimal hyperplasia within the body of the stent is the primary mechanism for in-stent restenosis; however, stent edge restenosis has been described after brachytherapy. Our current understanding about the magnitude of in vivo intimal hyperplasia and edge restenosis is limited to data obtained primarily from select, symptomatic patients requiring repeat angiography. The purpose of this study was to determine the extent and distribution of intimal hyperplasia both within the stent and along the stent edge in relatively nonselect, asymptomatic patients scheduled for 6-month intravascular ultrasound (IVUS) as part of a multicenter trial: Heparin Infusion Prior to Stenting. Planar IVUS measurements 1 mm apart were obtained throughout the stent and over a length of 10 mm proximal and distal to the stent at index and follow-up. Of the 179 patients enrolled, 140 returned for repeat angiography and IVUS at 6.4 +/- 1.9 months and had IVUS images adequate for analysis. Patients had 1.2 +/- 0.6 Palmaz-Schatz stents per vessel. There was a wide individual variation of intimal hyperplasia distribution within the stent and no mean predilection for any location. At 6 months, intimal hyperplasia occupied 29.3 +/- 16.2% of the stent volume on average. Lumen loss within 2 mm of the stent edge was due primarily to intimal proliferation. Beyond 2 mm, negative remodeling contributed more to lumen loss. Gender, age, vessel location, index plaque burden, hypercholesterolemia, diabetes, and tobacco did not predict luminal narrowing at the stent edges, but diabetes, unstable angina at presentation, and lesion length were predictive of in-stent intimal hyperplasia. In a non-radiation stent population, 29% of the stent volume is filled with intimal hyperplasia at 6 months. Lumen loss at the stent edge is due primarily to intimal proliferation.

  15. A review on fracture prevention of stent in femoropopliteal artery

    Science.gov (United States)

    Atan, Bainun Akmal Mohd; Ismail, Al Emran; Taib, Ishkrizat; Lazim, Zulfaqih

    2017-01-01

    Heavily calcific lesions, total occlusions, tortuous blood vessels, variable lengths of arteries, various dynamic loads and deformations in the femoropopliteal (FP) arterial segment make stenosis treatments are complicated. The dynamic forces in FP artery including bending, torsion and radial compression may lead to stent fracture (SF) and eventually to in-stent restenosis (ISR). Stent design specifically geometrical configurations are a major factor need to be improved to optimize stent expansion and flexibility both bending and torsion during stent deployment into the diseased FP artery. Previous studies discovered the influence of various stent geometrical designs resulted different structural behaviour. Optimizing stent design can improve stent performances: flexibility and radial strength to prevent SF in FP arterial segment

  16. 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.

  17. Direct drug-eluting stenting to reduce stent restenosis : a randomized comparison of direct stent implantation to conventional stenting with pre-dilation or provisional stenting in elective PCI patients

    NARCIS (Netherlands)

    Remkes, Wouter S; Somi, Samer; Roolvink, Vincent; Rasoul, Saman; Ottervanger, Jan Paul; Gosselink, A T Marcel; Hoorntje, Jan C A; Dambrink, Jan-Henk E; de Boer, Menko-Jan; Suryapranata, Harry; van 't Hof, Arnoud W J

    2014-01-01

    OBJECTIVES: The aim was to investigate whether a strategy of direct drug-eluting stent (DES) implantation without pre-dilation is associated with a reduced incidence of restenosis compared with CS with pre-dilation or provisional stenting (PS). BACKGROUND: Previous studies were performed comparing d

  18. 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.

  19. 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

  20. 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.

  1. 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.

  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 extractions in orthodontics

    OpenAIRE

    Camilo Aquino Melgaço; Mônica Tirre de Souza Araújo

    2012-01-01

    INTRODUCTION: Extraction decisions are extremely important in during treatment planning. In addition to the extraction decision orthodontists have to choose what tooth should be extracted for the best solution of the problem and the esthetic/functional benefit of the patient. OBJECTIVE: This article aims at reviewing the literature relating the advantages, disadvantages and clinical implications of asymmetric extractions to orthodontics. METHODS: Keywords were selected in English and Portugue...

  5. Asymmetric Evolutionary Games.

    Directory of Open Access Journals (Sweden)

    Alex McAvoy

    2015-08-01

    Full Text Available Evolutionary game theory is a powerful framework for studying evolution in populations of interacting individuals. A common assumption in evolutionary game theory is that interactions are symmetric, which means that the players are distinguished by only their strategies. In nature, however, the microscopic interactions between players are nearly always asymmetric due to environmental effects, differing baseline characteristics, and other possible sources of heterogeneity. To model these phenomena, we introduce into evolutionary game theory two broad classes of asymmetric interactions: ecological and genotypic. Ecological asymmetry results from variation in the environments of the players, while genotypic asymmetry is a consequence of the players having differing baseline genotypes. We develop a theory of these forms of asymmetry for games in structured populations and use the classical social dilemmas, the Prisoner's Dilemma and the Snowdrift Game, for illustrations. Interestingly, asymmetric games reveal essential differences between models of genetic evolution based on reproduction and models of cultural evolution based on imitation that are not apparent in symmetric games.

  6. Asymmetric extractions in orthodontics

    Directory of Open Access Journals (Sweden)

    Camilo Aquino Melgaço

    2012-04-01

    Full Text Available INTRODUCTION: Extraction decisions are extremely important in during treatment planning. In addition to the extraction decision orthodontists have to choose what tooth should be extracted for the best solution of the problem and the esthetic/functional benefit of the patient. OBJECTIVE: This article aims at reviewing the literature relating the advantages, disadvantages and clinical implications of asymmetric extractions to orthodontics. METHODS: Keywords were selected in English and Portuguese and the EndNote 9 program was used for data base search in PubMed, Web of Science (WSc and LILACS. The selected articles were case reports, original articles and prospective or retrospective case-control studies concerning asymmetrical extractions of permanent teeth for the treatment of malocclusions. CONCLUSION: According to the literature reviewed asymmetric extractions can make some specific treatment mechanics easier. Cases finished with first permanent molars in Class II or III relationship in one or both sides seem not to cause esthetic or functional problems. However, diagnosis knowledge and mechanics control are essential for treatment success.

  7. A simple technique to remove migrated esophageal stents.

    Science.gov (United States)

    Noyer, C M; Forohar, F

    1998-09-01

    A 51-yr-old man with a tracheoesophageal fistula from an esophageal carcinoma had two expandable covered stents placed, which migrated distally. After several unsuccessful attempts to remove the stents, we fashioned a homemade snare to entrap and remove the stents under endoscopic and fluoroscopic guidance.

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

    NARCIS (Netherlands)

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

    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

  9. 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...

  10. Early Stent Graft Perforation after Endovascular Repair for Pseudoaneurysm That Was Associated with Clavicle Nonunion

    Science.gov (United States)

    Touma, Masanao; Ohno, Nobuhisa; Yoshikawa, Eiji; Yoshizawa, Kousuke; Fujiwara, Keiichi

    2015-01-01

    We report the case of a 62-year-old man who experienced a left axillary artery pseudoaneurysm that was secondary to nonunion of a 30-year-old left midshaft clavicle fracture. He initially underwent endovascular repair using a self-expanding nitinol stent graft, which was perforated at postoperative day 5. Therefore, we performed open repair with concomitant clavicle resection, and no complications were observed during an approximately 6-year follow-up. We recommend performing clavicle resection with vascular repair to prevent recurrence in similar cases. PMID:26421082

  11. Multiobjective design optimisation of coronary stents.

    Science.gov (United States)

    Pant, Sanjay; Limbert, Georges; Curzen, Nick P; Bressloff, Neil W

    2011-11-01

    We present here a multi-objective and multi-disciplinary coronary stent design optimization paradigm. Coronary stents are tubular, often mesh-like, structures which are deployed in diseased (stenosed) artery segments to provide a scaffolding feature that compresses atheromatus plaque, hence restoring luminal area and maintaining vessel patency. A three variable geometry parameterisation of a CYPHER (Cordis Corporation, Johnson & Johnson co.) type stent is proposed to explore the functionality of a sequence of circumferential rings connected by 'n' shaped links. The performance of each design is measured by six figures of merit (objectives/metrics) representing (i) acute recoil, (ii) tissue stresses, (iii) haemodynamic disturbance, (iv) drug delivery, (v) uniformity of drug distribution, and (vi) flexibility. These metrics are obtained from computational simulations of (i) structural deformation through balloon inflated expansion of a stent into contact with a stenosed vessel, (ii) pulsatile flow over the deformed stent embedded in the vessel wall, (iii) steady-state drug distribution into the tissue, and (iv) flexibility of a stent in response to an applied moment. Design improvement is obtained by a multi-objective surrogate modelling approach using a non-dominated sorting genetic algorithm (NSGA-II) to search for an optimal family of designs. A number of trade-offs between the different objectives are identified. In particular a conflict between pairs of the following objectives are shown -- (a) volume average stress vs. recoil, (b) volume average drug vs. volume average stress, (c) flexibility vs. volume average stress, (d) flexibility vs. haemodynamic disturbance, (e) volume average drug vs. haemodynamic disturbance, and (f) uniformity of drug vs. volume average stress. Different paradigms to choose the optimal designs from the obtained Pareto fronts are presented and under each such paradigm, the optimal designs and there relative positions with respect to a

  12. 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.

  13. 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.……

  14. 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.

  15. 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.

  16. 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.

  17. [Ischaemic lesions of cerebral after carotid stenting].

    Science.gov (United States)

    Medvedev, R B; Tanashian, M M; Kuntsevich, G I; Lagoda, O V; Skrylev, S I; Krotenkova, M V; Koshcheev, A Iu; Suslin, A S; Gemdzhian, É G

    2015-01-01

    Carotid angioplasty with stenting is a reliable method of primary and secondary prevention of ischaemic stroke in patients with stenosing lesions of the internal carotid artery. However, carrying out such operations is sometimes associated with risk for the development of intraoperative impairments of cerebral circulation due to arterioarterial embolism in cerebral arteries, as well as vasospasm. Presented herein are the results of following up a total of 64 patients with pronounced atherosclerotic lesions of internal carotid arteries (>70%) - "symptomatic" and "asymptomatic", undergoing carotid stenting. Acute foci of ischaemia in the brain after stenting according to the findings of diffusion-weighted magnetic resonance tomography were revealed in 40% of cases, and in only 6% of patients they manifested themselves by symptoms of acute cerebral circulatory impairment. We revealed a direct correlation between the number, size of infarctions in the brain, and the appearance of neurological symptomatology. Intraoperative monitoring of blood flow in the middle cerebral artery during stenting makes it possible to predict the appearance of acute foci of cerebral ischaemia, to specify the genesis of perioperative stroke, as well as to evaluate clinical significance of vasospasm and material microembolism. The obtained findings should concentrate neurologists' attention on active postoperative follow up of patients subjected to carotid angioplasty with stenting in order to perform adequate personified neuroprotective correction, including preventive one.

  18. 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.

  19. Stent thrombosis, myocardial infarction, and death after drug-eluting and bare-metal stent coronary interventions

    DEFF Research Database (Denmark)

    Jensen, Lisette Okkels; Maeng, Michael; Kaltoft, Anne;

    2007-01-01

    OBJECTIVES: The aim of the study was to examine outcomes subsequent to implantation of drug-eluting stents (DES) and bare-metal stents (BMS). BACKGROUND: Use of DES might be associated with increased risk of stent thrombosis (ST), myocardial infarction (MI), and death. METHODS: From January 2002 ...

  20. 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.

  1. Drug-coated balloons are replacing the need for nitinol stents in the superficial femoral artery.

    Science.gov (United States)

    Kitrou, Panagiotis; Karnabatidis, Dimitrios; Katsanos, Konstantinos

    2016-08-01

    Amassed evidence from several randomized controlled trials and high quality meta-analyses clearly support the primary use of paclitaxel-coated balloons (PCB) in the superficial femoral artery over traditional plain balloon angioplasty or primary bare nitinol stenting with significantly lower vascular restenosis, less need for repeat procedures, improved quality of life and potential cost savings for the healthcare system. Stents may be reserved for bail-out in case of a suboptimal dilatation result, and for selected more complex lesions, or in case of critical limb ischemia in order to eliminate vessel recoil and maximize immediate hemodynamic gain. Debulking atherectomy remains unproven, but holds a lot of promise in particular in combination with PCBs, in order to improve compliance of the vessel wall by plaque removal, allow for a better angioplasty result and optimize drug transfer and bioavailability. The present overview summarizes and discusses current evidence about femoropopliteal PCB angioplasty compared to the historical standard of plain old balloon angioplasty and bare nitinol stents. Available evidence is appraised in the context of clinically meaningful results, relevant unresolved issues are highlighted, and future trends are discussed.

  2. 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

    -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...

  3. 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

  4. 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.

  5. 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...

  6. 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.

  7. Time-related changes in neointimal tissue coverage of a novel Sirolimus eluting stent

    Energy Technology Data Exchange (ETDEWEB)

    Secco, Gioel Gabrio, E-mail: gioel.gabrio.secco@gmail.com [Interventional Cardiology, “Santi Antonio e Biagio e Cesare Arrigo” Hospital, Alessandria (Italy); NIHR Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust, London (United Kingdom); Mattesini, Alessio [NIHR Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust, London (United Kingdom); Fattori, Rossella; Parisi, Rosario [Interventional Cardiology, “San Salvatore” Hospital, Pesaro (Italy); Castriota, Fausto [GVM Care and Research, Cotignola (Italy); Vercellino, Matteo [Interventional Cardiology, “Santi Antonio e Biagio e Cesare Arrigo” Hospital, Alessandria (Italy); Dall’Ara, Gianni [NIHR Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust, London (United Kingdom); Uguccioni, Lucia; Marinucci, Lucia [Interventional Cardiology, “San Salvatore” Hospital, Pesaro (Italy); De Luca, Giuseppe; Marino, Paolo Nicola [University of Eastern Piedmont, Novara (Italy); Pistis, Gianfranco [Interventional Cardiology, “Santi Antonio e Biagio e Cesare Arrigo” Hospital, Alessandria (Italy); Di Mario, Carlo [NIHR Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust, London (United Kingdom)

    2016-01-15

    Background: DES has reduced rates of restenosis compared with BMS but it has been associated with delayed healing and increase of stent thrombosis. The aim of our study was to evaluate the vascular time-related changes following implantation of a new SES coated with an amorphous silicon carbide that allows faster re-endothelisation (Orsiro-Biotronik). Methods: This prospective registry enrolled STEMI-patients with multi-vessel disease, thus candidates for a two-step procedure. PCI of the culprit lesion was performed with at least one Orsiro stent that was OCT-analysed during the second-step procedure (deferred to 30,90 and 180-days). Results: 16 of the 95 patients with MVD underwent an OCT evaluation of the study device implanted in the culprit lesion during the second-step staged procedure and were enrolled in the present Registry. A total of 3060-struts were analysed. The percentage of uncovered struts was 19.6% at30-days, 1.3% at90-days and 1.8% at180-days (p < 0.001). The percentage of cross section with ≥ 1 uncovered struts were 51.3% at30-days, 6.5% at90-days and 5.7% at180-days (p < 0.001). The percentage of cross sections containing thrombus was 6.2% at30-days while no thrombus was detected both at90 and 180-days. Conclusions: Our data shows that the new Orsiro stent promotes early and persistent strut coverage with low peri-strut thrombus. This pilot OCT evaluation might suggest a low incidence of late adverse events and anticipate safe outcome after early withdrawal of dual antiplatelet therapy. - Highlights: • This is the first serial study comparing coverage at 1, 3, and 6-months in consecutive patients with STEMI; • Aim of our study was to evaluate the vascular time-related changes following implantation of a new SES coated with an amorphous silicon carbide that allows faster re-endothelisation (Orsiro-Biotronik); • The main finding of this pilot study is that the study device presented a fast pattern of intimal coverage, with a thin intimal

  8. Recent developments in drug-eluting coronary stents.

    Science.gov (United States)

    Yildiz, Mustafa; Yildiz, Banu Sahin; Gursoy, Mustafa Ozan; Akin, Ibrahim

    2014-01-01

    The interventional treatment of coronary artery disease was introduced in 1970`s by Andreas Grüntzig. The initial treatment strategy with plain old balloon angioplasty (POBA) was associated with high restenosis rates. The introduction of coronary stents, especially drug-eluting stents (DES) in 2002 has improved the results by lowering the rate of in-stent restenosis from 20-40% in the era of bare-metal stent (BMS) to 6-8%. However, in 2006 with the observation of late stent thrombosis the reputations of DES have decreased. However, improvements in stent design especially antiproliferative agents, polymeric agents as well as stent platforms improved newer generation DES. In controlled trials as well as registries the use of second-generation DES as compared to bare-metal stents (BMS) was associated with better clinical and angiographic results. A further development of these stents with use of biodegradable polymers, polymer-free stents, and biodegradable stents on the basis of poly L-lactide (PLLA) or magnesium resulted in third-generation DES and has been evaluated in preclinical and first clinical trials. However, to date, there is a lack of data comparing these third-generation DES with first- and second-generatrion DES in a large scale.

  9. 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.

  10. 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

  11. Asymmetric flow networks

    OpenAIRE

    Olaizola Ortega, María Norma; Valenciano Llovera, Federico

    2012-01-01

    This paper provides a new model of network formation that bridges the gap between the two benchmark models by Bala and Goyal, the one-way flow model, and the two-way flow model, and includes both as particular extreme cases. As in both benchmark models, in what we call an "asymmetric flow" network a link can be initiated unilaterally by any player with any other, and the flow through a link towards the player who supports it is perfect. Unlike those models, in the opposite direction there is ...

  12. Cerrobend shielding stents for buccal carcinoma patients

    Directory of Open Access Journals (Sweden)

    Karma Yangchen

    2016-01-01

    Full Text Available Buccal carcinoma is one of the most common oral malignant neoplasms, especially in the South Asian region. Radiotherapy, which plays a significant role in the treatment of this carcinoma, has severe adverse effects. Different types of prosthesis may be constructed to protect healthy tissues from the adverse effects of treatment and concentrate radiation in the region of the tumor mass. However, the technique for fabrication of shielding stent with Lipowitz's alloy (cerrobend/Wood's alloy has not been well documented. This article describes detailed technique for fabrication of such a stent for unilateral buccal carcinoma patients to spare the unaffected oral cavity from potential harmful effects associated with radiotherapy.

  13. Automated stent strut coverage and apposition analysis of in-vivo intra coronary optical coherence tomography images

    Science.gov (United States)

    Ughi, Giovanni J.; Adriaenssens, Tom; Onsea, Kevin; Kayaert, Peter; Dubois, Christophe; Coosemans, Mark; Sinnaeve, Peter; Desmet, Walter; D'hooge, Jan

    2011-03-01

    Several studies have proven that intra-vascular OCT is an appropriate imaging modality able to evaluate stent strut apposition and coverage in coronary arteries. Currently image processing is performed manually resulting in a very time consuming and labor intensive procedure. We propose an algorithm for fully automatic individual stent strut apposition and coverage analysis in coronary arteries. The vessel lumen and stent strut are automatically detected and segmented through analysis of the intensity profiles of the A-scan lines. From these data, apposition and coverage can then be estimated automatically. The algorithm was validated using manual measurement (performed by two trained cardiologists) as a reference. 108 images were taken at random from in-vivo pullbacks from 9 different patient presenting 'real-life' situations (i.e. blood residual, small luminal objects and artifacts). High Pearson's correlation coefficients were found (R = 0.96 - 0.95) between the automated and manual measurements while Bland-Altman statistics showed no significant bias with good limits of agreement. As such, it was shown that the presented algorithm provides a robust and a fast tool to automatically estimate apposition and coverage of stent struts in in-vivo pullbacks. This will be important for the integration of this technology in clinical routine and large clinical trials.

  14. 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.

  15. Drug-eluting stents in renal artery stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Zaehringer, M. [Marienhospital Stuttgart, Department of Radiology, Stuttgart (Germany); Pattynama, P.M.T. [Erasmus MC-University Medical Center Rotterdam, Rotterdam (Netherlands); Talen, A. [genae associates nv, Antwerp (Belgium); Sapoval, M. [Hopital Europeen Georges Pompidou, Service de Radiologie Cardio-Vasculaire, Paris (France); Inserm U 780 epidemiologie Cardio Vasculaire, Paris (France)

    2008-04-15

    Because of higher acute and long-term success rates compared with balloon angioplasty alone, percutaneous stent implantation has become an accepted therapy for the treatment of atherosclerotic renal artery stenosis. Restenosis rates after successful renal stent placement vary from 6 up to 40%, depending on the definition of restenosis, the diameter of the treated vessel segment and comorbidities. The safety and efficacy of drug-eluting stents for the treatment of renal-artery stenosis is poorly defined. The recently published GREAT study is the only prospective study, comparing bare-metal and sirolimus-coated low profile stent systems in renal artery stenosis, showing a relative risk reduction of angiographic binary in-stent restenosis by 50%. This is an opinion paper on indications, current treatment options and restenosis rates following renal artery stenting and the potential use of drug-eluting stents for this indication. (orig.)

  16. 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...

  17. 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.

  18. 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.

  19. Hemocompatibility Improvement of Chromium-Bearing Bare-Metal Stent Platform After Magnetoelectropolishing

    Science.gov (United States)

    Rokicki, Ryszard; Haider, Waseem; Maffi, Shivani Kaushal

    2015-01-01

    Research was undertaken to determine the influence of the increased content of chromium in the outermost passive layer of magneto-electrochemically refined Co-Cr alloy L-605 surface on its hemocompatibility. The chemistry, roughness, surface energy, and wettability of conventionally electropolished (EP) and magnetoelectropolished (MEP) samples were studied with x-ray photoelectron spectroscopy (XPS), open circuit potential, atomic force microscopy, and contact angle meter. In vitro hemocompatibility of tested material surfaces was assessed using two important indicators of vascular responses to biomaterial, namely endothelialization and platelets adhesion. The endothelialization was assessed by seeding and incubating samples with human umbilical vein endothelial cells (HUVEC) for 3 days before counting and observing them under a fluorescent microscope. The platelet (rich plasma blood) adhesion and activation test on EP and MEP L-605 alloy surfaces was assessed using a laser scanning confocal microscope. The XPS analysis of MEP samples showed significant enrichment of the passive layer with Cr and O when compared with the EP one. The amount of other elements in the passive layer did not show a significant difference between EP and MEP treatments. The adhesion of HUVEC cells shows remarkable affinity to surfaces enriched in Cr (MEP) with almost 100% confluency. In addition, the number of platelets that adhered to standard EP surfaces was higher compared to the MEP surface. The present study shows that the chromium-enriched surface of cobalt-chromium alloy L-605 by the magnetoelectropolishing process tremendously improves surface hemocompatibility with regard to stent functionality by enhanced endothelialization and lower platelet adhesion and should be taken under consideration as an alternative surface of biodegradable polymer drug-eluting stents, polymer-free drug-eluting stents as well as bare-metal stents.

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. Morphologic characteristics of late stent malapposition after drug-eluting stents implantation by optical coherence tomography follow-up

    Institute of Scientific and Technical Information of China (English)

    HOU Jing-bo; LIU Hui-min; MA Li-jia; YANG Shuang; MENG Ling-bo; HAN Zhi-gang; ZHANG Shuo; YU Bo

    2010-01-01

    Background Late stent malapposition was frequently observed after DES implantation, which has been associated with the occurrence of late stent thrombosis due to poor neointimal coverage. This study was designed to evaluate the frequency of late stent malapposition at least 1 year after different DESs implantation by optical coherence tomography (OCT). Methods Angiographic and OCT examinations were given to 68 patients who had received total 126 various DESs implantation for at least 1 year to detect late stent malapposition. Malapposed strut distance (MSD), malapposed strut area (MSA), reference lumen area (RLA) and reference stent area (RSA) were checked with off-line OCT analysis. Results Totally 26 Cypher Select stents, 15 Taxus Liberte stents, 51 Partner stents and 34 Firebird I stents were examined. Among 68 patients who underwent DES implantation, 7 patients (10.3%) had late malapposition. Average RSA, MSA and MSD were (7.9±2.8)mm~2,(2.0±1.6)mm~2 and (590±270)μm respectively.According to the MSA/RSA ratio,4 patients had slight malapposition,2 patients had moderate malapposition and 1 patient had severe malapposition.Conclusions Late stent malapposition is detected frequently after implantation of DES,but if this predisposes to late stent thrombosis and requires any specific therapy needs to be further elucidated.

  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. Inflammation and in-stent restenosis: the role of serum markers and stent characteristics in carotid artery stenting.

    Directory of Open Access Journals (Sweden)

    Katrin Wasser

    Full Text Available BACKGROUND: Carotid angioplasty and stenting (CAS may currently be recommended especially in younger patients with a high-grade carotid artery stenosis. However, evidence is accumulating that in-stent restenosis (ISR could be an important factor endangering the long-term efficacy of CAS. The aim of this study was to investigate the influence of inflammatory serum markers and procedure-related factors on ISR as diagnosed with duplex sonography. METHODS: We analyzed 210 CAS procedures in 194 patients which were done at a single university hospital between May 2003 and June 2010. Periprocedural C-reactive protein (CRP and leukocyte count as well as stent design and geometry, and other periprocedural factors were analyzed with respect to the occurrence of an ISR as diagnosed with serial carotid duplex ultrasound investigations during clinical long-term follow-up. RESULTS: Over a median of 33.4 months follow-up (IQR: 14.9-53.7 of 210 procedures (mean age of 67.9±9.7 years, 71.9% male, 71.0% symptomatic an ISR of ≥70% was detected in 5.7% after a median of 8.6 months (IQR: 3.4-17.3. After multiple regression analysis, leukocyte count after CAS-intervention (odds ratio (OR: 1.31, 95% confidence interval (CI: 1.02-1.69; p = 0.036, as well as stent length and width were associated with the development of an ISR during follow-up (OR: 1.25, 95% CI: 1.05-1.65, p = 0.022 and OR: 0.28, 95% CI: 0.09-0.84, p = 0.010. CONCLUSIONS: The majority of ISR during long-term follow-up after CAS occur within the first year. ISR is associated with periinterventional inflammation markers and influenced by certain stent characteristics such as stent length and width. Our findings support the assumption that stent geometry leading to vessel injury as well as periprocedural inflammation during CAS plays a pivotal role in the development of carotid artery ISR.

  7. 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.

  8. 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.)

  9. 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.

  10. 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.)

  11. 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

  12. 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

  13. Lesion load in unprotected carotid artery stenting

    Energy Technology Data Exchange (ETDEWEB)

    Grunwald, I.Q.; Papanagiotou, P.; Roth, C.; Karp, K.; Krick, C.; Schieber, H.; Mueller, M.; Reith, W. [University of the Saarland, Department for Diagnostic and Interventional Neuroradiology, Homburg (Germany); Fassbender, K.; Haass, A. [University of the Saarland, Division of Neurology, Homburg (Germany)

    2009-05-15

    The purpose of the study was to determine the incidence of new ischemic lesions found on diffusion-weighted MR imaging (DWI) in nonselected patients after unprotected carotid artery stent placement. We retrospectively reviewed a nonrandomized cohort of 197 patients presenting with carotid occlusive disease who underwent unprotected carotid artery stent placement between 2003 and 2006. Mean degree of stenosis was 86.94% {+-} 9.72. In all patients, DWI was obtained before and 24 h after stent placement. New lesions were evaluated according to size and location. In 59 of 197 patients (29.9%), new ischemic lesions were found on DWI in the vessel dependent area. In 23 of 197 patients (11.7%), new ischemic lesions were found in the vessel independent area. Combined stroke/death rate was 3.63%. In our series of unprotected carotid angioplasty with stent, we found new DWI lesions in 34% of the patients. Further studies should now show in how far protection devices can reduce these lesions. (orig.)

  14. 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.

  15. Improvement of Stent Retriever Design and Efficacy of Mechanical Thrombectomy in a Flow Model

    Energy Technology Data Exchange (ETDEWEB)

    Wenger, Katharina, E-mail: kwenger@stud.uni-frankfurt.de [Institute of Neuroradiology, University of Frankfurt am Main (Germany); Nagl, Frank, E-mail: fnagl@acandis.com [Acandis GmbH and Co KG (Germany); Wagner, Marlies, E-mail: Marlies.Wagner@kgu.de; Berkefeld, Joachim, E-mail: berkefeld@em.uni-frankfurt.de [Institute of Neuroradiology, University of Frankfurt am Main (Germany)

    2013-02-15

    In vitro experiments were performed to evaluate the efficacy of mechanical intracranial thrombectomy comparing the newly developed Aperio stent retriever and standard devices for stroke treatment. The Aperio (A), with an increased working length of 4 cm and a special cell design for capturing and withholding clots, was compared to three benchmark devices: the Solitaire retrievable stent (B), the Merci X6 (C), and the Merci L5 retriever (D). In a vascular glass model with pulsatile flow, reminiscent of the M1 segment of the middle cerebral artery, we repeatedly induced occlusion by generating thrombi via a modified Chandler loop system. The numbers of recanalization attempts, peripheral embolizations, and recanalizations at the site of occlusion were recorded during 10 retrieval experiments with each device. Eleven devices were able to remove the blood clots from the occluded branch. In 34 of 40 experiments, restoration of flow was obtained in 1-3 attempts. The main differences between the study devices were observed in terms of clot withholding and fragmentation during retrieval. Although there was only one fragmentation recorded for device A, disengagement of the whole clot or peripheral embolization of fragments occurred more frequently (5-7 times) with devices B, C, and D. In a vascular model, the design of device A was best at capturing and withholding thrombi during retrieval. Further study will be necessary to see whether this holds true in clinical applications.

  16. 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.

  17. Assessment Of Coronary Arterial Stents By Multislice-CT Angiography

    Energy Technology Data Exchange (ETDEWEB)

    Maintz, D.; Fallenberg, E. M.; Heindel, W.; Fischbach, R. [Univ. of Muenster (Germany). Dept. of Clinical Radiology; Grude, M. [Univ. of Muenster (Germany). Dept. of Cardiology and Angiology

    2003-11-01

    Purpose: To assess patency and lumen visibility of coronary artery stents by multislice-CT angiography (MSCTA) in comparison with conventional coronary angiography as the standard of reference. Material and Methods: 47 stents of 13 different types were evaluated in 29 patients. MSCTA was performed on a 4-slice scanner with a standard coronary protocol (detector collimation 4 x 1 mm; table feed 1.5 mm/rotation, 400 mAs, 120 kV). Image evaluation was performed by two readers who were blinded to the reports from the catheter angiography. MIP reconstructions were evaluated for image quality on a 4-point scale (1 = poor, 4 = excellent) and stent patency (contrast distal to the stent as an indirect patency sign). Axial images and multiplanar reformations through the stents were used for assessment of stent lumen visibility (measurement of the visible stent lumen diameter) and detection of relevant in-stent stenosis (50%). Results: Image quality was fair to good on average (score 2.64 {+-} 1.0) and depended on the heart rate (heart rate 45-60: average score 3.2, heart rate 61-70: average score 2.8, heart rate >71: average score 1.4). Thirty-seven stents were correctly classified as patent, 1 was correctly classified as occluded and 9 stents were not assessable due to insufficient image quality because of triggering artifacts. Parts of the stent lumen could be visualized in 30 cases. On average, 20-40% of the stent lumen diameter was visible. Twenty-five stents were correctly classified as having no stenosis, 1 was falsely classified as stenosed, 1 was correctly classified as occluded. In 20 stents lumen visibility was not sufficient for stenosis evaluation. Conclusion: Although the stent lumen may be partly visualized in most stents, a reliable evaluation of in-stent stenoses does not seem practical by 4-slice MSCT. Nevertheless, for stent patency evaluation, MS-CTA might provide valuable clinical information. With submillimeter MSCT (e.g. 16-slice scanners) and more

  18. Malignant Ureteral Obstruction: Functional Duration of Metallic versus Polymeric Ureteral Stents.

    Directory of Open Access Journals (Sweden)

    Po-Ming Chow

    Full Text Available Ureteral obstruction caused by extrinsic compression is often associated with intra-abdominal cancers. Internal drainage with ureteral stents is typically the first-line therapy to relieve such obstructions. Novel designs of ureteral stents made of different materials have been invented to achieve better drainage. In this study, we described the functional outcomes of a Resonance metallic ureteral stent (Cook Medical, Bloomington, Indiana, USA in patients with malignant ureteral obstruction and compare the functional duration of Resonance stents with regular polymeric stents in the same cohort.Cancer patients who received polymeric stents and subsequent Resonance stents for ureteral obstruction between July 2009 and November 2012 were included in a chart review. Stent failure was detected by clinical symptoms, imaging studies, and renal function tests. The functional durations of each stent were calculated, and possible factors affecting stent patency were investigated.A total of 50 stents were successfully inserted into 50 ureteral units in 42 patients with malignant ureteral obstruction. There were 7 antegrade stents and 43 retrograde stents. There were no major complications. Stent-related symptoms were similar in both kinds of stents. After polymeric stents were replaced with Resonance metallic stents, hydronephrosis subsided or remained stable in 90% (45/50 of the ureteral units. Serum creatinine decreased or remained stable in 90% (38/42 of these patients. The Resonance stent exhibited a mean increase in functional duration of 4 months compared with the polymeric stents (p<0.0001, and 50% (25/50 of the Resonance stents exhibited a significant increase in functional duration (more than 3 months. Pre-operative serum creatinine < 2 was associated with a substantial increase in stent duration.Resonance stents are effective and safe in relieving malignant ureteral obstructions after polymeric stents failure. Resonance stents can provide a

  19. Additive Effects on Asymmetric Catalysis.

    Science.gov (United States)

    Hong, Liang; Sun, Wangsheng; Yang, Dongxu; Li, Guofeng; Wang, Rui

    2016-03-23

    This review highlights a number of additives that can be used to make asymmetric reactions perfect. Without changing other reaction conditions, simply adding additives can lead to improved asymmetric catalysis, such as reduced reaction time, improved yield, or/and increased selectivity.

  20. Are bio-absorbable stents the future of SFA treatment?

    Science.gov (United States)

    Peeters, P; Keirse, K; Verbist, J; Deloose, K; Bosiers, M

    2010-02-01

    Several limitations inherent to the implantation of a metallic device, such as the occurrence of in-stent re-stenosis, in an arterial lumen intuitively explain the interest for developing bio-absorbable stents. Two main types of bio-absorbable stents currently exist: polymer stents and metallic stents. To date, no studies with bio-absorbable stents have been conducted in the superficial femoral artery (SFA). Because of their strut thickness and lack of radial force, polymer stents are no good candidates for endovascular use. Absorbable metal stents (AMS) do have the potential to perform well for artery treatment, although current evidence from in-human coronary and infrapopliteal studies yield unsatisfactory results. Drastic technological improvements are mandatory before AMS can be considered for every day practice. Yet, it is our belief that further development of other metal and non-metal bio-absorbable stents, with or without drug-coating, may lead to the creation of the ultimate SFA stent.

  1. Computational Analysis on Stent Geometries in Carotid Artery: A Review

    Science.gov (United States)

    Paisal, Muhammad Sufyan Amir; Taib, Ishkrizat; Ismail, Al Emran

    2017-01-01

    This paper reviews the work done by previous researchers in order to gather the information for the current study which about the computational analysis on stent geometry in carotid artery. The implantation of stent in carotid artery has become popular treatment for arterial diseases of hypertension such as stenosis, thrombosis, atherosclerosis and embolization, in reducing the rate of mortality and morbidity. For the stenting of an artery, the previous researchers did many type of mathematical models in which, the physiological variables of artery is analogized to electrical variables. Thus, the computational fluid dynamics (CFD) of artery could be done, which this method is also did by previous researchers. It lead to the current study in finding the hemodynamic characteristics due to artery stenting such as wall shear stress (WSS) and wall shear stress gradient (WSSG). Another objective of this study is to evaluate the nowadays stent configuration for full optimization in reducing the arterial side effect such as restenosis rate after a few weeks of stenting. The evaluation of stent is based on the decrease of strut-strut intersection, decrease of strut width and increase of the strut-strut spacing. The existing configuration of stents are actually good enough in widening the narrowed arterial wall but the disease such as thrombosis still occurs in early and late stage after the stent implantation. Thus, the outcome of this study is the prediction for the reduction of restenosis rate and the WSS distribution is predicted to be able in classifying which stent configuration is the best.

  2. Stents: Biomechanics, Biomaterials, and Insights from Computational Modeling.

    Science.gov (United States)

    Karanasiou, Georgia S; Papafaklis, Michail I; Conway, Claire; Michalis, Lampros K; Tzafriri, Rami; Edelman, Elazer R; Fotiadis, Dimitrios I

    2017-04-01

    Coronary stents have revolutionized the treatment of coronary artery disease. Improvement in clinical outcomes requires detailed evaluation of the performance of stent biomechanics and the effectiveness as well as safety of biomaterials aiming at optimization of endovascular devices. Stents need to harmonize the hemodynamic environment and promote beneficial vessel healing processes with decreased thrombogenicity. Stent design variables and expansion properties are critical for vessel scaffolding. Drug-elution from stents, can help inhibit in-stent restenosis, but adds further complexity as drug release kinetics and coating formulations can dominate tissue responses. Biodegradable and bioabsorbable stents go one step further providing complete absorption over time governed by corrosion and erosion mechanisms. The advances in computing power and computational methods have enabled the application of numerical simulations and the in silico evaluation of the performance of stent devices made up of complex alloys and bioerodible materials in a range of dimensions and designs and with the capacity to retain and elute bioactive agents. This review presents the current knowledge on stent biomechanics, stent fatigue as well as drug release and mechanisms governing biodegradability focusing on the insights from computational modeling approaches.

  3. Drug- and Gene-eluting Stents for Preventing Coronary Restenosis

    Science.gov (United States)

    Lekshmi, Kamali Manickavasagam; Che, Hui-Lian; Cho, Chong-Su

    2017-01-01

    Coronary artery disease (CAD) has been reported to be a major cause of death worldwide. Current treatment methods include atherectomy, coronary angioplasty (as a percutaneous coronary intervention), and coronary artery bypass. Among them, the insertion of stents into the coronary artery is one of the commonly used methods for CAD, although the formation of in-stent restenosis (ISR) is a major drawback, demanding improvement in stent technology. Stents can be improved using the delivery of DNA, siRNA, and miRNA rather than anti-inflammatory/anti-thrombotic drugs. In particular, genes that could interfere with the development of plaque around infected regions are conjugated on the stent surface to inhibit neointimal formation. Despite their potential benefits, it is necessary to explore the various properties of gene-eluting stents. Furthermore, multifunctional electronic stents that can be used as a biosensor and deliver drug- or gene-based on physiological condition will be a very promising way to the successful treatment of ISR. In this review, we have discussed the molecular mechanism of restenosis, the use of drug- and gene-eluting stents, and the possible roles that these stents have in the prevention and treatment of coronary restenosis. Further, we have explained how multifunctional electronic stents could be used as a biosensor and deliver drugs based on physiological conditions. PMID:28184335

  4. 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.

  5. Microguidewire Looping to Traverse Stented Parent Arteries of Intracranial Aneurysms

    Science.gov (United States)

    Cho, Young Dae; Rhim, Jong Kook; Yoo, Dong Hyun; Kang, Hyun-Seung; Kim, Jeong Eun; Han, Moon Hee

    2017-01-01

    Objective Stents are widely used in coil embolization of intracranial aneurysms, but on occasion, a microcatheter must traverse a stented segment of artery (so-called trans-cell technique) to select an aneurysm, or double stenting may necessary. In such situations, microguidewire passage and microcatheter delivery through a tortuous stented parent artery may pose a technical challenge. Described herein is a microguidewire looping technique to facilitate endovascular navigation in these circumstances. Methods To apply this technique, the microguidewire tip is looped before entering the stented parent artery and then advanced distally past the stented segment, with the loop intact. Rounding of the tip prevents interference from stent struts during passage. A microcatheter is subsequently passed into the stented artery for positioning near the neck of aneurysm, with microguidewire assistance. The aneurysm is then selected, steering the microcatheter tip (via inner microguidewire) into the dome. Results This technique proved successful during coil embolization of nine saccular intracranial aneurysms (internal carotid artery [ICA], 6; middle cerebral artery, 2; basilar tip, 1), performing eight trans-cell deliveries and one additional stenting. Selective endovascular embolization was enabled in all patients, resulting in excellent clinical and radiologic outcomes, with no morbidity or mortality directly attributable to microguidewire looping. Conclusion Microguidewire looping is a reasonable alternative if passage through a stented artery is not feasible by traditional means, especially at paraclinoid ICA sites. PMID:28264249

  6. 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.

  7. 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.

  8. Usefulness of flexible covered stent in malignant colorectal obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Jee Hee; Kang, Sung Gwon; Kim, Hyung Jin; Noh, Hong Gi; Woo, Jae Hong; Suh, Chang Hae [Inha Univ. Hospital, Inchon (Korea, Republic of)

    1998-07-01

    To evaluate the usefulness of flexible covered stent in the treatment of acute colorectal obstruction secondary to colorectal carcinoma. Materials and Methods : Flexible covered stents were placed in 11 patients with clinical and radiologic signs of acute colonic obstruction secondary to colorectal carcinoma. The purposes of stent insertion were pre-operative bowel preparation in seven patients and palliative treatment in four. A fistula was present in two;in one this was between the proximal jejunum and colon, and the other was rectovaginal. The usefulness of stent insertion for the purpose of preoperative bowel preparation was evaluated according to the feasibility and status of bowel preparation, as decided by the operator. Palliative treatment for the relief of symptoms of acute bowel obstruction was evaluated according to the number and amount of defecation,bowel dilatation in simple abdomen radiography, and the presence of complications. Results : Bowel preparation for the purpose of preoperative bowel cleansing was easy in seven patients;the fecal materials remaining in the colon presented no problems during surgery. In one of four patients palliative treatment involved a colostomy;this was due to recurrent stent obstruction by fecal materials after three months, and in two other patients there was stent obstruction after two and five months, respectively. The stent in one of four patients who underwent palliative treatment was removed because of stent migration three days after insertion;the stents in two patients with fistulas covered the fistulas successfully. Complications after stent insertion were anal pain in three patients, anal bleeding in three and stent migration in one. Conclusion : The flexible covered stent was an effective device for the relief of acute colonic obstruction secondary to malignant rectosigmoid neoplasia. It allowed for single-stage operation and covered the fistula. We believe however that for further evaluation of the

  9. Carotid Artery Stenting 2013: Thumbs up

    Science.gov (United States)

    Wagdi, Philipp

    2013-01-01

    It has been customary for interventional cardiologists involved in carotid artery stenting, to underline non-inferiority of the percutaneous technique versus surgical carotid endarterectomy. To that end, all cause morbidity and mortality figures of both methods are compared. Surgery has, in most large randomized studies, had an edge over stenting in terms of cerebrovascular adverse events. This may have partly been due to occasional indiscriminate indication for stenting in lesions and/or vessels with unfavourable characteristics (severe target vessel tortuosity and calcification, Type III aortic arch, and so on). On one hand, the author pleads for improvement of the excellent results of endarterectomy, by subjecting all patients planned for surgery to a thorough preoperative cardiological work up, including generous invasive investigation, thus reducing the incidence of perioperative myocardial infarction, heart failure and cardiac death. On the other hand, we are convinced that the results of carotid stenting should then be compared to best practice surgery. The rate of neurological adverse event rate after carotid endarterectomy at our institution lies under 0.7% at 30 days postoperatively. Specifically, the goal should be that carotid stenting underbids surgical endarterectomy, also and mainly, in terms of cerebral and cerebrovascular adverse events. Cardiac morbidity and mortality as well as laryngeal nerve palsy should no more be the main arguments for the percutaneous approach. This should easily be possible if patient selection for carotid revascularisation would be approached according to morphological criteria, in analogy with the “Syntax”-score used to optimise revascularisation strategies in coronary artery disease.

  10. The asymmetric sandwich theorem

    CERN Document Server

    Simons, Stephen

    2011-01-01

    We discuss the asymmetric sandwich theorem, a generalization of the Hahn-Banach theorem. As applications, we derive various results on the existence of linear functionals that include bivariate, trivariate and quadrivariate generalizations of the Fenchel duality theorem. Most of the results are about affine functions defined on convex subsets of vector spaces, rather than linear functions defined on vector spaces. We consider both results that use a simple boundedness hypothesis (as in Rockafellar's version of the Fenchel duality theorem) and also results that use Baire's theorem (as in the Robinson-Attouch-Brezis version of the Fenchel duality theorem). This paper also contains some new results about metrizable topological vector spaces that are not necessarily locally convex.

  11. 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.

  12. Paclitaxel Drug-eluting Tracheal Stent Could Reduce Granulation Tissue Formation in a Canine Model

    Directory of Open Access Journals (Sweden)

    Ting Wang

    2016-01-01

    Conclusions: The paclitaxel-eluting stent could safely reduce the granulation tissue formation after stent implantation in vivo, suggesting that the paclitaxel-eluting tracheal stent might be considered for potential use in humans in the future.

  13. 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,

  14. Direct coronary stent implantation: safety, feasibility, and predictors of success of the strategy of direct coronary stent implantation.

    Science.gov (United States)

    Laarman, G; Muthusamy, T S; Swart, H; Westendorp, I; Kiemeneij, F; Slagboom, T; van der Wieken, R

    2001-04-01

    This prospective study was designed to evaluate the feasibility, safety, predictive factors of success, and 6-month follow-up of stent implantation without balloon predilatation (direct stenting) in 250 patients undergoing elective stent implantation. Balloon dilatation prior to stent implantation was a prerequisite to facilitate passage and deployment of the stent. Stent technology has changed tremendously, resulting in stents with improved properties, which may allow stent placement without prior balloon dilatation. Patients with coronary lesions suitable for elective stent implantation were included in this trial. Coronary interventions were undertaken predominantly via the transradial route using 6 Fr guiding catheters. Direct stent implantation was attempted using AVE GFX II coronary stent delivery systems. Upon failure, predilatation was undertaken before reattempting stent implantation. Patient data and ECGs were obtained from case records and from personal or telephone interviews 6 months after the procedure. Values were presented as mean +/- standard deviation. Student's t-test, two-tailed at 5% level of significance, was used to compare the difference of two means. Multivariate logistic regression analysis was performed to establish predictive factors for failure of direct stenting. Two hundred and sixty-six direct stent implantations were attempted in 250 patients. Direct stenting was successful in 226 (85%) cases. Out of 40(15%) cases where direct stenting failed, balloon predilatation facilitated stent implantation in 39. In one lesion, stent implantation was not possible despite adequate predilatation. Predictive factors for failure of direct stenting on multivariate analysis were LCx lesions (P < 0.01), complex lesions (P < 0.01), and longer stents (P < 0.001). Minimal luminal diameter and percentage diameter stenosis of lesions in the successful and the failure group were not significantly different (0.94 +/- 0.39 mm vs. 0.84 +/- 0.41 mm, P = NS

  15. 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.

  16. Carotid artery stenting: Rationale, technique, and current concepts

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, Hasan, E-mail: hasan.yilmaz@hcuge.c [Department of Interventional and Diagnostic Neuroradiology, University Hospital of Geneva (Switzerland); Pereira, Vitor Mendes; Narata, Ana-Paula [Department of Interventional and Diagnostic Neuroradiology, University Hospital of Geneva (Switzerland); Sztajzel, Roman [Department of Neurology, University Hospital of Geneva (Switzerland); Lovblad, Karl-Olof [Department of Interventional and Diagnostic Neuroradiology, University Hospital of Geneva (Switzerland)

    2010-07-15

    Carotid stenosis is a major risk factor for stroke. With the aging of the general population and the availability of non-invasive vascular imaging studies, the diagnosis of a carotid plaque is commonly made in medical practice. Asymptomatic and symptomatic carotid stenoses need to be considered separately because their natural history is different. Two large randomized controlled trials (RCTs) showed the effectiveness of carotid endarterectomy (CEA) in preventing ipsilateral ischemic events in patients with symptomatic severe stenosis. The benefit of surgery is much less for moderate stenosis and harmful in patients with stenosis less than 50%. Surgery has a marginal benefit in patients with asymptomatic stenosis. Improvements in medical treatment must be taken into consideration when interpreting the results of these previous trials which compared surgery against medical treatment available at the time the trials were conducted. Carotid artery stenting (CAS) might avoid the risks associated with surgery, including cranial nerve palsy, myocardial infarction, or pulmonary embolism. Therefore and additionally to well-established indications of CAS, this endovascular approach might be a valid alternative particularly in patients at high surgical risk. However, trials of endovascular treatment of carotid stenosis have failed to provide enough evidence to justify routine CAS as an alternative to CEA in patients suitable for surgery. More data from ongoing randomized trials of CEA versus CAS will be soon available. These results will help determining the role of CAS in the management of patients with carotid artery stenosis.

  17. 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...

  18. 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.

  19. Comparison of Acute Recoil between Bioabsorbable Poly-L-lactic Acid XINSORB Stent and Metallic Stent in Porcine Model

    Directory of Open Access Journals (Sweden)

    Yizhe Wu

    2012-01-01

    Full Text Available Objective. To investigate acute recoil of bioabsorbable poly-L-lactic acid (PLLA stent. Background. As newly developed coronary stent, bioabsorbable PLLA stent still encountered concern of acute stent recoil. Methods. Sixteen minipigs were enrolled in our study. Eight PLLA XINSORB stents (Weite Biotechnology Co., Ltd., China and eight metallic stents (EXCEL, Jiwei Co., Ltd. China were implanted into coronary arteries. Upon quantitative coronary angiography analysis, acute absolute recoil was defined as the difference between mean diameter of inflated balloon (X and mean lumen diameter of stent immediately after deployment (Y, while acute percent recoil was defined as (X−Y/X and expressed as a percentage. Intravascular ultrasound (IVUS was performed immediately after implantation and 24 hours later to compare cross-sectional area (CSA between two groups and detect stent malapposition or collapse. Results. Acute absolute recoil in XINSORB and EXCEL was 0.02±0.13 mm and −0.08±0.08 mm respectively (P=0.19. Acute percent recoil in XINSORB and EXCEL was 0.66±4.32% and −1.40±3.83%, respectively (P=0.45. CSA of XINSORB was similar to that of EXCEL immediately after implantation, so was CSA of XINSORB at 24-hours followup. Within XINSORB group, no difference existed between CSA after implantation and CSA at 24-hours followup. No sign of acute stent malapposition was detected by IVUS. Conclusions. The acute stent recoil of XINSORB is similar to that of EXCEL. No acute stent malapposition or collapse appeared in both kinds of stent. This preclinical study was designed to provide preliminary data for future studies of long-term efficacy and safety of XINSORB stent.

  20. Mode of deployment of coronary Palmaz-Schatz stents after implantation with the stent delivery system: an intravascular ultrasound study.

    Science.gov (United States)

    Kiemeneij, F; Laarman, G; Slagboom, T

    1995-04-01

    The stent delivery system (SDS) is a sheath-covered Palmaz-Schatz stent mounted on a 3.0, 3.5, or 4.0 mm compliant polyethylene balloon catheter; the balloon resists maximal inflation pressures of 5.7, 6.2, or 6.0 atm, respectively. It is postulated that these pressures are too low to obtain optimal stent deployment. Because optimal stent deployment is a prerequisite for optimal short- and long-term outcome, we performed an intravascular ultrasound study to the mode of stent deployment after delivery with the SDS and after high-pressure dilatations with low-compliant, oversized balloon catheters. In 23 patients an intravascular ultrasound study (30 MHz, 4.3F transducer) was performed to the geometry of 29 stents immediately after delivery with the SDS and after successive high-pressure inflations with low-compliant balloons. After delivery with the SDS (3.3 +/- 0.4 mm), stent diameter was 3.0 +/- 0.4 mm. After high-pressure dilatations (12.4 +/- 1.4 atm) with low-compliant balloons (3.9 +/- 0.5 mm), stent diameter increased to 3.4 +/- 0.4 mm (p < 0.001). Only 8 (28%) stents were completely and symmetrically expanded to the corresponding reference diameter with good apposition after delivery with the SDS. Diameter of incomplete deployed stents (n = 16) was 2.8 +/- 0.3 mm. After high-pressure dilatations with low-compliant balloons (3.9 +/- 0.5 mm), diameter increased to 3.4 +/- 0.4 mm (p < 0.001). Now 20 (69%) stents (p = 0.004) became completely and symmetrically expanded to a diameter corresponding to the reference diameter. In conclusion, most stents are suboptimally deployed after delivery with the stent delivery system.(ABSTRACT TRUNCATED AT 250 WORDS)

  1. 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.

  2. 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.

  3. Stone Formation and Fragmentation in Forgotten Ureteral Double J Stent

    Directory of Open Access Journals (Sweden)

    Okan Bas

    2014-02-01

    Full Text Available Aim: Nowadays, ureteral stents play an essential role in various endourological and open surgical procedures and common procedures performed in daily urological practice. However, stents can cause significant complications such as migration, infection, fragmentation, stone formation and encrustation, especially when forgotten for a long period. Objectives: We present our experience in endoscopic management of forgotten ureteral stents with a brief review of current literature. Case presentation: A total of 2 patients with forgotten ureteral stents were treated with endourological approaches in our department. Indwelling durations were 18 months and 36 months. After treatment both patients were stone and stent free. Conclusion: An endourological approach is effective for stent and stone removal after a single anesthesia session with minimal morbidity and short hospital stay. However, therapeutic strategy is also determined by the technology available. The best treatment would be the prevention of this complication by providing detailed patient education.

  4. Irradiation and dosimetry of Nitinol stent for renal artery brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Arbabi, Azim [Science and Research Campus, Islamic Azad University, P.O. Box 14515-775, Tehran (Iran, Islamic Republic of); Shahid Beheshti Medical University, P.O. Box 14335-1419, Tehran (Iran, Islamic Republic of); Sadeghi, Mahdi [Science and Research Campus, Islamic Azad University, P.O. Box 14515-775, Tehran (Iran, Islamic Republic of); Nuclear Medicine Research Group, Agricultural, Medical and Industrial Research School, P.O. Box 31485-498, Karaj (Iran, Islamic Republic of)], E-mail: msadeghi@nrcam.org; Joharifard, Mahdi [Science and Research Campus, Islamic Azad University, P.O. Box 14515-775, Tehran (Iran, Islamic Republic of)

    2009-01-15

    This study was conducted to assess the suitability of {sup 48}V radioactive stent for use in renal artery brachytherapy. A nickel-titanium alloy Nitinol stent was irradiated over the proton energy range of up to 8.5 MeV, to obtain {sup 48}V. The depth dose distribution analysis of the activated stent was done with TLD-700GR in a Perspex phantom. We investigated a unique mixed gamma/beta brachytherapy source of {sup 48}V. For a 10 mm outer-diameter {sup 48}V stent, the average measured dose rate to vessel was 37 mGy/h. The dosimetry results of the {sup 48}V stent suggest that the stent is suitable for use in renal artery brachytherapy.

  5. Mathematical model of carotid artery for stent placement

    Science.gov (United States)

    Rahman, Tengku Husna Tengku Abdul; Din, Ummul Khair Salma; Ahmad, Rokiah @ Rozita

    2016-11-01

    The carotid artery stenting is one of the methods used to reduce the effect of artherosclerosis which caused by the thickening of the artery wall. In most of the studies, the measure of wall elasticity, shear stress and the blood pressure through the blood flow were considered. The aim of this study is to determine the position to place the stent inside the carotid artery. A mathematical model is reconstructed to determine the suitable location of the stent in the carotid artery. Throughout the study, differences in fluid flow between a normal carotid artery wall and stenosed carotid artery wall are investigated. Since the existence of the stenosis provides a resistance in the flow, it is important to identify the right position to place the stent. The stent will be placed in the position where stenosis exists to ease the blood to flow normally. Later after the stent placement, the blood flow normally through the blood vessel.

  6. On high-cycle fatigue of 316L stents.

    Science.gov (United States)

    Barrera, Olga; Makradi, Ahmed; Abbadi, Mohammed; Azaouzi, Mohamed; Belouettar, Salim

    2014-01-01

    This paper deals with fatigue life prediction of 316L stainless steel cardiac stents. Stents are biomedical devices used to reopen narrowed vessels. Fatigue life is dominated by the cyclic loading due to the systolic and diastolic pressure and the design against premature mechanical failure is of extreme importance. Here, a life assessment approach based on the Dang Van high cycle fatigue criterion and on finite element analysis is applied to explore the fatigue reliability of 316L stents subjected to multiaxial fatigue loading. A finite element analysis of the stent vessel subjected to cyclic pressure is performed to carry out fluctuating stresses and strain at some critical elements of the stent where cracks or complete fracture may occur. The obtained results show that the loading path of the analysed stent subjected to a pulsatile load pressure is located in the safe region concerning infinite lifetime.

  7. 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.

  8. A Covered Nitinol Stent Fracture in a Patient with a Malignant Esophageal Stricture: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hee Jin; Cho, Yun Ku; Kim, Wan Tae [Seoul Veterans Hospital, Seoul (Korea, Republic of)

    2008-11-15

    Self-expanding metallic stent insertion has been widely applied for the palliative treatment of malignant esophageal strictures. Although it is known as an easy, safe, and effective procedure, complications are well known and include things such as stent migration and esophageal stent occlusion caused by tumor in growth. However, metallic stent fractures have been rarely reported in the esophagus, especially for nitinol stents. We report a case of a stent fracture associated with migration in a patient with a malignant esophageal stricture near the gastroesophageal junction. It is highly probable that the stent fracture was due to chemical erosion of the stent caused by gastric juice

  9. 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.

  10. Reação histopatológica da parede da aorta abdominal ao stent não recoberto Histopathological reaction of the abdominal aorta wall to non-covered stents

    Directory of Open Access Journals (Sweden)

    Rubio Bombonato

    2006-06-01

    Full Text Available OBJETIVO: Avaliar a reação histopatológica da parede aorta abdominal, em suínos, no nível das artérias renais, na presença de stent metálico não recoberto. MÉTODO: Foi estudada histopatologicamente a aorta abdominal de 10 suínos, com peso médio de 86,6 quilos e idade média de 6 meses, submetidos a implante de stent metálico posicionado na aorta, no nível das artérias renais, após 100 dias do implante. Os stents foram liberados por auto-expansão com laparotomia. Os cortes histológicos foram realizados nos seguintes locais: 1 transição entre a aorta normal e aorta contendo stent; 2 aorta contendo o stent; 3 porção contendo os óstios das artérias renais, 4 linfonodos periaórticos e, 5 parênquima renal. As lâminas foram coradas pela técnica da hematoxilina e eosina. RESULTADOS: Os achados macroscópicos revelaram: linfonodomegalia periaórtica; espessamento da parede aórtica; artérias lombares e renais pérvias; estrutura anatômica renal normal. Análises microscópicas, próximas aos stents, evidenciaram espessamento da parede vascular, secundário à fibrose intimal e camada média comprometida com fibrose intersticial. Medidas micrométricas da parede aórtica com o stent, comparada à aorta sem o stent, apresentaram aumento da espessura da parede (75,9% por hiperplasia da camada íntima secundária à proliferação de fibroblastos; depósitos de colágeno com infiltrado inflamatório e granulomas do tipo corpo estranho. CONCLUSÃO: O stent de aço inoxidável descoberto, implantado na aorta de suínos, produziu importante reação inflamatória, com fibrose nas camadas média e íntima, evidenciada pelas análises histopatológicas e a sua presença não comprometeu o estado pérvio da aorta e dos ramos lombares e renais.OBJECTIVE: To evaluate the histopathological reaction of the abdominal aorta wall in pigs' renal arteries to the presence of non-covered stainless steel stents. METHODS: The abdominal aorta of

  11. 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.

  12. PTA and stent placement distal to the superficial femoral artery; PTA und Stent distal der AFS

    Energy Technology Data Exchange (ETDEWEB)

    Rand, T.; Stadler, A.; Schoder, M.; Kettenbach, J. [Medizinische Universitaet Wien, Klinische Abteilung fuer Angiographie und Interventionelle Radiologie, Wien (Austria); Haumer, M. [Klinik fuer Innere Medizin II des Universitaetsklinikums Wien, Klinische Abteilung fuer Angiologie, Wien (Austria)

    2006-11-15

    Although angioplasty and stent applications in the iliac vessels and the superficial femoral artery have become routine procedures, their usefulness for the treatment of lesions of the popliteal artery and the lower leg arteries is still under discussion. For the popliteal artery, limitations are mainly due to the high mechanical stress in this area, causing high traction forces. Moreover, beyond the occlusive atherosclerotic changes, specific pathological entities such as aneurysms, emboli, entrapment syndromes, and cystic adventitial disease have to be differentiated. There is hope that the development of innovative stent designs with high flexibility might overcome the limitations. For lesions of the lower leg arteries treatment with percutaneous transluminal angioplasty (PTA) has become the method of choice. However, stent designs as used for cardiac interventions have been adapted for their application below the knee, and first encouraging results may help to justify their broad use in the future. Regarding PTA, innovative equipment and techniques for the treatment of arterial lesions below the knee include dedicated, long, and very flexible balloons, cutting balloon cryoplasty, and laser angioplasty. Regarding stents, bare metal stents, stents with passive or active coatings, and bioabsorbable stents have all been successfully used. (orig.) [German] Waehrend Angioplastie (PTA) und Stentbehandlung im Bereich der Beckengefaesse sich zu etablierten interventionellen Standardverfahren entwickelt haben, ist die endovaskulaere Behandlung von Laesionen der A. poplitea und auch der Unterschenkelgefaesse noch in Diskussion. Gruende hierfuer sind bei der A. poplitea v. a. die unguenstigen mechanischen Faktoren, die hohe Traktionskraefte am Gefaess wirken lassen und besonders die Gefaesspathologien, die neben der stenosierenden Atherosklerose auch andere spezifische Auspraegungen wie Aneurysmen, Embolien, Entrapmentsyndrome und die zystische Adventitianekrose umfassen

  13. 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....

  14. 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.

  15. 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...

  16. 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....... 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....

  17. 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.

  18. 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.

  19. Percutaneous transradial artery approach for coronary stent implantation.

    Science.gov (United States)

    Kiemeneij, F; Laarman, G J

    1993-10-01

    A new approach for implantation of Palmaz Schatz coronary stents is reported. We describe the technique and rationale of coronary stenting with miniaturized angioplasty equipment via the radial artery. This technique is illustrated in three patients. One patient underwent Palmaz Schatz stent implantation for a saphenous vene coronary bypass graft stenosis, the second patient for a restenosis in the anterior descending coronary artery after atherectomy, and the third patient for a second restenosis after balloon angioplasty in the circumflex coronary artery.

  20. Direct coronary stenting by transradial approach: rationale and technical issues.

    Science.gov (United States)

    Burzotta, Francesco; Hamon, Martial; Trani, Carlo; Kiemeneij, Ferdinand

    2004-10-01

    Direct stent implantation using radial approach represents to date the less invasive, less traumatic strategy to perform a percutaneous coronary intervention, rendering its adoption an attraction for many interventional cardiologists. A growing series of reports suggests the feasibility of transradial direct stenting in a variety of clinical situations. Here we discuss the main advantages of the adoption of this technique. Moreover, a detailed analysis of the technical issues specifically related with each phase of transradial direct stenting procedures is reported.

  1. 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.

  2. 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.)

  3. 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.)

  4. [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.

  5. [Magnetic resonance compatibility research for coronary mental stents].

    Science.gov (United States)

    Wang, Ying; Liu, Li; Wang, Shuo; Shang, Ruyao; Wang, Chunren

    2015-01-01

    The objective of this article is to research magnetic resonance compatibility for coronary mental stents, and to evaluate the magnetic resonance compatibility based on laboratory testing results. Coronary stents magnetic resonance compatibility test includes magnetically induced displacement force test, magnetically induced torque test, radio frequency induced heating and evaluation of MR image. By magnetic displacement force and torque values, temperature, and image distortion values to determine metal coronary stent demagnetization effect. The methods can be applied to test magnetic resonance compatibility for coronary mental stents and evaluate its demagnetization effect.

  6. 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...

  7. Society for Vascular Medicine

    Science.gov (United States)

    ... Certification with this new online course from the Society for Vascular Medicine. Learn more. Looking for a ... jobs are listed right now. Copyright © 2016 The Society for Vascular Medicine. All Rights Reserved.

  8. Performance characteristics of self-expanding peripheral nitinol stents; Vergleich mechanischer Eigenschaften von selbst expandierenden peripheren Stents

    Energy Technology Data Exchange (ETDEWEB)

    Wissgott, C.; Andresen, R. [Inst. fuer diagnostische und interventionelle Radiologie/Neuroradiologie, Westkuestenklinikum Heide, Akademisches Lehrkrankenhaus der Universitaeten Kiel, Luebeck und Hamburg (Germany); Schmidt, W.; Behrens, P.; Schmitz, K.P. [Inst. fuer Biomedizinische Technik, Univ. Rostock (Germany)

    2009-06-15

    Purpose: to evaluate geometric-mechanical characteristics of self-expanding peripheral nitinol stents, such as alignment to the vessel wall, flexibility and radial force, in order to obtain information as to which stent is most appropriate depending on the characteristics of the arterial lesion. Materials and methods: the in vitro tests were done on seven stent systems: Acculink, Zilverstent, Philon, Precise, Luminexx, SelfX and Sinus Super-Flex. All stents had a diameter of 8 mm and a length from 37 - 44 mm. The stents were evaluated for traceability and profile, radial force, flexibility and radiopacity. Stents were even evaluated for alignment to the vessel wall using a zigzag-shaped model and a model with a diameter step from 5 to 7 mm. Assessment considered the distance to the vessel wall and diameter reduction and in step-mode the smooth and harmonic transition. Results: at a stent diameter of 7 mm, radial forces between 1.09 (Sinus Super-Flex) and 2.59 N (Philon) were measured. The flexibility of the expanded stents ranged from 11.7 (Acculink) to 88.1 Nmm{sup 2} (Luminexx). The Precise and Philon stents yielded the best alignment to the vessel wall, while the SelfX and Sinus Superflex stents had the highest reduction in diameter and the largest distance from the vessel wall in a tortuous vessel model. Differences in vessel diameter were best bridged by stents with short segments (Acculink, Precise). All stents were readily visible after expansion. (orig.)

  9. 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.

  10. Drug-eluting stents below the knee.

    Science.gov (United States)

    Bosiers, M; Deloose, K; Callaert, J; Keirse, K; Verbist, J; Peeters, P

    2011-04-01

    The fear that early thrombosis and late luminal loss due to intimal hyperplasia formation potentially leads to insufficient long-term patency rates can explain the reluctance on implanting stents in small diameter below-the-knee (BTK) arteries. Drug-eluting stent (DES) technology was developed to prevent early thrombosis and late luminal loss to potentially improve long-term patency rates. Currently, the first level 1 evidence from prospective, randomized, controlled DESTINY and ACHILLES studies indicate that the implantation of DES in short lesion lenghts in the infrapopliteal vasculature leads to favorable outcomes with high primary patency rates. This makes that primary DES placement can be recommended as treatment strategy in short BTK-lesions.

  11. 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 life....

  12. 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.

  13. Endovascular treatment of peripheral arterial injury with covered stents: an experimental study in pigs

    Directory of Open Access Journals (Sweden)

    Sergio Belczak

    2011-01-01

    Full Text Available OBJECTIVE: To evaluate the feasibility of using endovascular repair to treat penetrating arterial injuries with covered stents. Feasibility was examined according to the circumferential extent of the injury. INTRODUCTION: Surgical trauma often increases the risk of major morbidity and mortality associated with vascular injury, and endovascular repair has many advantages in such situations. METHODS: Twenty white male domestic pigs weighing 28-38 kg with controlled vascular injuries were divided into four equal groups according to the circumferential extent of their vascular lesion (i.e., no lesion, lesion 50%, and complete lesion. The left common carotid artery was dissected with proximal and distal control, and this procedure was followed by controlled sectioning of the arterial wall. Local manual compression was applied for 10 min and was followed by endovascular repair with the placement of a 5x50 mm VIABHAN TM covered stent using the femoral approach. We also monitored additional variables, such as the duration of the procedures (the mean was 56.3 ± 19.1 min, ultrasound parameters (e.g., maximum arterial diameter, peak systolic and diastolic velocity, and resistance index, arteriography findings, and fluctuations in vital signs (e.g., cardiac output, arterial pressure, and central venous pressure. RESULTS: The experimental procedure was found to be feasible and reproducible. Repairs were successful in all animals in the control (no lesion and 50% group and in one pig in the complete lesion group. DISCUSSION: The endovascular repair of an arterial injury is possible, but success depends on the circumferential extent of the arterial lesion. The present experimental model, which involved endovascular techniques, highlighted important factors that must be considered in future studies involving similar animals and materials.

  14. Comparison of Bare metal Vs Drug eluting stents for in-stent Restenosis among Diabetics

    Directory of Open Access Journals (Sweden)

    Kakhaber Etsadashvili

    2011-06-01

    Full Text Available Background: Diabetes mellitus is associated with an increased risk of restenosis, stent thrombosis, and death afterpercutaneous coronary interventions. Little is known about the late outcome of patients with diabetes mellitus whoreceive drug-eluting stents (DES or bare metal stents (BMS.Methods: From January 2008 to January 2010, six patients with DES and 20 with BMS, ISR were identified at ourinstitution.Results: The median age of our diabetic cohort was 63 years, and 87 of the patients were male. For two years, ratesof repeat target-vessel revascularization were significantly lower among diabetic patients treated with DEScompared with those treated with BMS (5.8% vs. 17.0%, p=0.003.Conclusions: DES is effective among diabetic patients in substantially reducing the need for repeat TVR.

  15. [Results of the upper digestive tract stenting with self-expanding stents].

    Science.gov (United States)

    Fedorov, A G; Davydova, S V; Klimov, A E; Lebedev, N V

    2013-01-01

    The work is based on the analysis of the palliative treatment of 66 patients with malignant upper digestive tract obstruction who underwent implantation of 75 self-expanding metallic stents in the period of 2003-2012 yy. Early postoperative complications developed in 10 (15.2%) cases. Procedure-related complications were observed in 8 (12.1%) patients, non-specific complications occurred in 2 (3.0%) patients. In-hospital lethality was 4.5% (3 patients). 51 patients were followed until death. Symptomatic relapse of obstruction was observed in 4 cases. Median survival was 97 days. Stenting with self-expanding metal stents was concluded to be an effective and safe method of palliation of malignant upper digestive tract stenosis.

  16. 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.

  17. 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.

  18. Particle imaging velocimetry evaluation of intracranial stents in sidewall aneurysm: hemodynamic transition related to the stent design.

    Science.gov (United States)

    Bouillot, Pierre; Brina, Olivier; Ouared, Rafik; Lovblad, Karl-Olof; Farhat, Mohamed; Pereira, Vitor Mendes

    2014-01-01

    We investigated the flow modifications induced by a large panel of commercial-off-the-shelf (COTS) intracranial stents in an idealized sidewall intracranial aneurysm (IA). Flow velocities in IA silicone model were assessed with and without stent implantation using particle imaging velocimetry (PIV). The use of the recently developed multi-time-lag method has allowed for uniform and precise measurements of both high and low velocities at IA neck and dome, respectively. Flow modification analysis of both regular (RSs) and flow diverter stents (FDSs) was subsequently correlated with relevant geometrical stent parameters. Flow reduction was found to be highly sensitive to stent porosity variations for regular stents RSs and moderately sensitive for FDSs. Consequently, two distinct IA flow change trends, with velocity reductions up to 50% and 90%, were identified for high-porosity RS and low-porosity FDS, respectively. The intermediate porosity (88%) regular braided stent provided the limit at which the transition in flow change trend occurred with a flow reduction of 84%. This transition occurred with decreasing stent porosity, as the driving force in IA neck changed from shear stress to differential pressure. Therefore, these results suggest that stents with intermediate porosities could possibly provide similar flow change patterns to FDS, favourable to curative thrombogenesis in IAs.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    and KCN, are selectively bound to the catalyst, providing exceptionally high enantioselectivities for kinetic resolutions, elimination reactions (fluoride base), and Strecker synthesis (cyanide nucleophile). Asymmetric cation-binding catalysis was recently expanded to silicon-based reagents, enabling...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...

  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. 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

  8. Imaging of coronary artery stents using multislice computed tomography: in vitro evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Maintz, David; Juergens, Kai-Uwe; Heindel, Walter; Fischbach, Roman [Department of Clinical Radiology, University of Muenster, Albert-Schweitzer-Strasse 33, 48129 Muenster (Germany); Wichter, Thomas; Grude, Matthias [Department of Cardiology and Angiology, University of Muenster, Albert-Schweitzer-Strasse 33 48129 Muenster (Germany)

    2003-04-01

    The aim of this study was to evaluate imaging features of different coronary artery stents during multislice CT Angiography (MSCTA). Nineteen stents made of varying material (steel, nitinol, tantalum) and of varying stent design were implanted in plastic tubes with an inner diameter of 3 mm to simulate a coronary artery. The tubes were filled with iodinated contrast material diluted to 200 Hounsfield units (HU), closed at both ends and positioned in a plastic container filled with oil (-70 HU). The MSCT scans were obtained perpendicular to the stent axes (detector collimation 4 x 1 mm, table feed 2 mm/rotation, 300 mAs, 120 kV). Axial images and multiplanar reformations were evaluated regarding artifact size, lumen visibility, and intraluminal attenuation values. Artifacts characterized by artifactual thickening of the stent struts leading to apparent reduction in the lumen diameter and increased intraluminal attenuation values were observed in all cases. The stent lumen was totally obscured in the Wiktor stent, the Wallgraft stent, and the Nir Royal stent. Partial residual of the stent lumen could be visualized in all other utilized stent products (artificial lumen reductions ranged from 62% in the V-Flex stent to 94% in the Bx Velocity stent). Parts of the stent lumen can be visualized in most coronary artery stents; however, detectability of in-stent stenoses remains to be evaluated for each stent type. (orig.)

  9. Investigation of Stent Implant Mechanics Using Linear Analytical and Computational Approach.

    Science.gov (United States)

    Yang, Hua; Fortier, Aleksandra; Horne, Kyle; Mohammad, Atif; Banerjee, Subhash; Han, Hai-Chao

    2017-03-01

    Stent implants are essential in restoring normal blood flow in atherosclerotic arteries. Recent studies have shown high failure rates of stent implants in superficial femoral artery (SFA) as a result of dynamic loading environment imposed on the stent implants by the diseased arterial wall and turbulent blood flow. There are variety of stent designs and materials currently on the market however, there is no clear understanding if specific stent design is suitable with the material that is manufactured from and if this combination can sustain the life-cycle that the stent implants need to undergo once inside the artery. Lack of studies have been presented that relate stent mechanical properties with stent geometry and material used. This study presents linear theoretical and computational modeling approach that determines stent mechanical properties with effective stiffness of the deployed stent. Effective stiffness of the stent has been accurately derived based on stent structure design and loading in axial and radial directions. A rhombus stent structure was selected for this study due to its more common use and produced by main stream manufacturers. The derived theoretical model was validated using numerical finite element modeling approach. Results from this study can lead to preliminary insight towards understanding of stent deformation based on stent geometry, material properties and artery wall pressure; and how to carefully match stent's geometry with suitable material for long life cycle, increased strength, and reliable performance of stent implants.

  10. Stent-assisted coiling of wide-necked intracranial aneurysms using the Solitaire AB stent

    Directory of Open Access Journals (Sweden)

    Vikram Huded

    2014-01-01

    Full Text Available Context: Stent-assisted coiling of wide-necked and complex intracranial aneurysms is an effective and feasible treatment option. The self-expanding, fully retrievable Solitaire AB (eV3, Irvine, CA, USA stent is the latest neurovascular remodeling device available. To the best of our knowledge, there are no studies of Solitaire AB-assisted coiling of wide-necked intracranial aneurysms from India. Aim: Solitaire AB-assisted coiling of wide-necked intracranial aneurysms. Materials and Methods: The study was conducted in a tertiary care center with a dedicated Interventional Neurology division from 2009 to 2013. Consecutive patients with wide-necked aneurysms who underwent coiling assisted by the Solitaire AB stent were enrolled in the study. Axium 3D and Helix (eV3, Irvine, CA, USA platinum coils were used to densely pack the aneurysm sac after deploying the stent across the neck. All patients were pretreated with antiplatelets according to protocol. Subsequently, dual antiplatelets were given for 6 months followed by continued aspirin. Outcome was assessed at 3 months using the modified Rankin Scale. Statistical Analysis Used: Statistical analysis was done using the SPSS 17.0 software. Results: A total of 16 patients underwent stent-assisted coiling. The most common site was the internal carotid artery (nine patients, median aneurysm size was 7 mm and median neck diameter was 5 mm. Thirteen patients presented with ruptured aneurysms. We achieved complete occlusion in all patients with no major complications. Thirteen patients were followed up, all have an mRS score of zero or one. Conclusion: We conclude that for wide-necked aneurysms, stent-assisted coiling using the Solitaire AB is a safe and effective treatment option.

  11. Sellado de aneurisma coronario con stent cubierto de PTFE (stent graft)

    OpenAIRE

    Portero Pérez,Ma Pilar; Ortas Nadal,Ma Rosario; Ruiz Arroyo,José Ramón; Escota Villanueva,Javier; Peleato Peleato,Antonio

    2008-01-01

    Los aneurismas coronarios son muy raros, su frecuencia oscila entre el 1 y el 2%, siendo la aterosclerosis la enfermedad más asociada, aunque se han descrito los de origen congénito, los asociados a la enfermedad de Kawasaki, a enfermedades del tejido conectivo, a enfermedades infecciosas y a traumatismos torácicos. También se observan los relacionados con la implantación del stent, con la braquiterapia intracoronaria y con los "stents" recubiertos de fármacos. Su evolución no es muy bien con...

  12. Application of a mechanobiological simulation technique to stents used clinically.

    Science.gov (United States)

    Boyle, Colin J; Lennon, Alex B; Prendergast, Patrick J

    2013-03-15

    Many cardiovascular diseases are characterised by the restriction of blood flow through arteries. Stents can be expanded within arteries to remove such restrictions; however, tissue in-growth into the stent can lead to restenosis. In order to predict the long-term efficacy of stenting, a mechanobiological model of the arterial tissue reaction to stress is required. In this study, a computational model of arterial tissue response to stenting is applied to three clinically relevant stent designs. We ask the question whether such a mechanobiological model can differentiate between stents used clinically, and we compare these predictions to a purely mechanical analysis. In doing so, we are testing the hypothesis that a mechanobiological model of arterial tissue response to injury could predict the long-term outcomes of stent design. Finite element analysis of the expansion of three different stent types was performed in an idealised, 3D artery. Injury was calculated in the arterial tissue using a remaining-life damage mechanics approach. The inflammatory response to this initial injury was modelled using equations governing variables which represented tissue-degrading species and growth factors. Three levels of inflammation response were modelled to account for inter-patient variability. A lattice-based model of smooth muscle cell behaviour was implemented, treating cells as discrete agents governed by local rules. The simulations predicted differences between stent designs similar to those found in vivo. It showed that the volume of neointima produced could be quantified, providing a quantitative comparison of stents. In contrast, the differences between stents based on stress alone were highly dependent on the choice of comparison criteria. These results show that the choice of stress criteria for stent comparisons is critical. This study shows that mechanobiological modelling may provide a valuable tool in stent design, allowing predictions of their long

  13. Coronary Stent Materials and Coatings: A Technology and Performance Update.

    Science.gov (United States)

    O'Brien, Barry; Zafar, Haroon; Ibrahim, Ahmad; Zafar, Junaid; Sharif, Faisal

    2016-02-01

    This paper reviews the current state of the art for coronary stent materials and surface coatings, with an emphasis on new technologies that followed on from first-generation bare metal and drug-eluting stents. These developments have been driven mainly by the need to improve long term outcomes, including late stent thrombosis. Biodegradable drug-eluting coatings aim to address the long term effects of residual durable polymer after drug elution; the SYNERGY, BioMatrix, and Nobori stents are all promising devices in this category, with minimal polymer through the use of abluminal coatings. Textured stent surfaces have been used to attached drug directly, without polymer; the Yukon Choice and BioFreedom stents have some promising data in this category, while a hydroxyapatite textured surface has had less success. The use of drug-filled reservoirs looked promising initially but the NEVO device has experienced both technical and commercial set-backs. However this approach may eventually make it to market if trials with the Drug-Filled Stent prove to be successful. Non-pharmacological coatings such as silicon carbide, carbon, and titanium-nitride-oxide are also proving to have potential to provide better performance than BMS, without some of the longer term issues associated with DES. In terms of biological coatings, the Genous stent which promotes attachment of endothelial progenitor cells has made good progress while gene-eluting stents still have some practical challenges to overcome. Perhaps the most advancement has been in the field of biodegradable stents. The BVS PLLA device is now seeing increasing clinical use in many complex indications while magnesium stents continue to make steady advancements.

  14. Role of metallic stents in benign esophageal stricture

    Science.gov (United States)

    Shim, Chan Sup

    2012-10-01

    Simple esophageal strictures, which are focal, straight, and large in diameter, usually require 1 - 3 dilation sessions to relieve symptoms. However, complex strictures, which are long, tortuous, or associated with a severely compromised luminal diameter, are usually more difficult to treat with conventional bougie or balloon dilation techniques, and often have high recurrence rates. Although the permanent placement of self-expandable metal stents (SEMS) has been used to manage refractory benign esophageal strictures, this procedure is associated with additional problems, such as stricture from tissue hyperplasia, stent migration, and fistula formation. Thus, several new types of stents have been developed, including temporary SEMS, self-expandable plastic stents (SEPS), and biodegradable stents. The use of these new products has produced varied results. Temporary SEMS that have been used to relieve benign esophageal conditions have caused granulation tissue at both ends of the stent because of contact between the mucosa and the exposed metal components of the stent, thus hindering stent removal. We examined the tissue response to two new types of SEMS, a flange-type and a straighttype, each coated with a silicone membrane on the outside of the metal mesh. These two SEMS were evaluated individually and compared with a conventional control stent in animal experiments. Although the newly designed stents resulted in reduced tissue hyperplasia, and were thus more easily separated from the esophageal tissue, some degree of tissue hyperplasia did occur. We suggest that newly designed DES (drug-eluting stents) may provide an alternative tool to manage refractory benign esophageal stricture.

  15. Comparison of in vivo acute stent recoil between the bioabsorbable everolimus-eluting coronary stent and the everolimus-eluting cobalt chromium coronary stent: insights from the ABSORB and SPIRIT trials

    DEFF Research Database (Denmark)

    Tanimoto, Shuzou; Serruys, Patrick W; Thuesen, Leif

    2007-01-01

    the antiproliferative drug, everolimus, and expected to be totally metabolized and absorbed in the human body. Because the BVS is made from polymer, it may have more acute recoil than metallic stents in vivo. METHODS: A total of 54 patients, who underwent elective stent implantation for single de novo native coronary......OBJECTIVES: This study sought to evaluate and compare in vivo acute stent recoil of a novel bioabsorbable stent and a metallic stent. BACKGROUND: The bioabsorbable everolimus-eluting coronary stent (BVS) is composed of a poly-L-lactic acid backbone, coated with a bioabsorbable polymer containing...

  16. [Biodegradable catheters and urinary stents. When?

    Science.gov (United States)

    Soria, F; Morcillo, E; López de Alda, A; Pastor, T; Sánchez-Margallo, F M

    2016-10-01

    One of the main wishes in the field of urinary catheters and stents is to arm them with biodegradable characteristics because we consider a failure of these devices the need for retrieval, the forgotten catheter syndrome as well as the adverse effects permanent devices cause after fulfilling their aim. The efforts focused in new designs, coatings and biomaterials aim to increase the biocompatibility of theses internal devices. Lately, there have been correct advances to answer the main challenges regarding biodegradable ureteral devices. Thus, modulation of the rate of degradation has been achieved thanks to new biomaterials and the use of copolymers that enable to choose the time of permanence as it is programmed with conventional double J catheters. Biocompatibility has improved with the use of new polymers that adapt better to the urine. Finally, one of the main problems is elimination of degraded fragments and experimentally it has be demonstrated that new designs elicit controlled degradation, from distal to proximal; using stranding and combination of copolymers degradation may be caused by dilution, reducing fragmentation to the last stages of life of the prosthesis. Moreover, it has been demonstrated that biodegradable catheters potentially may cause less urinary tract infection, less encrustation and predictably they will diminish catheter morbidity, since their degradation process reduces adverse effects. Regarding the development of biodegradable urethral stents, it is necessary to find biomaterials that enable maintaining their biomechanical properties in the long term, keeping open the urethral lumen both in patients with BPH and urethral stenosis. Modulation of the time of degradation of the prosthesis has been achieved, but the appearance of urothelial hyperplasia is still a constant in the initial phases after implantation. The development of drug eluting stents, anti-proliferative or anti-inflammatory, as well as biodegradable stents biocoated is a

  17. Anatomical features and management of bioresorbable vascular scaffolds failure: A case series from the GHOST registry.

    Science.gov (United States)

    Longo, Giovanni; Granata, Francesco; Capodanno, Davide; Ohno, Yohei; Tamburino, Claudia Ina; Capranzano, Piera; La Manna, Alessio; Francaviglia, Bruno; Gargiulo, Giuseppe; Tamburino, Corrado

    2015-06-01

    The Absorb bioresorbable vascular scaffold (Absorb BVS, Abbott Vascular, Santa Clara, California) promises to address some of the residual shortcomings of existing metallic stents, such as late events induced by permanent caging of the coronary vessel. Scaffold restenosis (ScR) of BVS has been poorly described so far and treatment strategies for this event remain to be codified. We report on a case series of 14 lesions in 12 patients presenting with ScR and discuss their anatomical features and management strategies. © 2015 Wiley Periodicals, Inc.

  18. Expression and function of calcium-activated potassium channels following in-stent restenosis in a porcine coronary artery model

    Directory of Open Access Journals (Sweden)

    Mais F. Absi

    2012-04-01

    Functional analysis using 1-EBIO and Bradykinin produced hyperpolarization of neointimal but not medial myocytes, which indicated the expression of functional endothelial SK3 and IKCa in the former and not in the latter. The expression of IKCa and SK3 within the neointimal layer suggested that some degree of recovery of both endothelial as well as smooth muscle regeneration had occurred. Future development of selective modulators of IKCa and SK3 channels may decrease the progression of ISR and improve coronary vascular function after stent placement, and is an area for future investigation.

  19. Open triple-branched stent graft applied to patient of acute type a aortic dissection with Aberrant Right Subclavian Artery

    OpenAIRE

    Guo, Changfa; Zhu, Kai; Xu, Demin; Wang, Chunsheng

    2013-01-01

    A 57-year-old Chinese male patient presented with Standford type A aortic dissection with an aberrant right subclavian artery (ARSA). At operation, the ascending aorta was replaced by a mono–branch vascular prosthesis with the branch bypassing to the ARSA; the triple-branched stent graft was inserted into the true lumen of the arch and proximal descending aorta (covering the origin of the ARSA) with each sidearm graft being positioned into the aortic branches; and then its proximal end was su...

  20. 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

  1. 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.

  2. Biodegradable Metals for Cardiovascular Stent Application: Interests and New Opportunities

    Directory of Open Access Journals (Sweden)

    Maryam Moravej

    2011-06-01

    Full Text Available During the last decade, biodegradable metallic stents have been developed and investigated as alternatives for the currently-used permanent cardiovascular stents. Degradable metallic materials could potentially replace corrosion-resistant metals currently used for stent application as it has been shown that the role of stenting is temporary and limited to a period of 6–12 months after implantation during which arterial remodeling and healing occur. Although corrosion is generally considered as a failure in metallurgy, the corrodibility of certain metals can be an advantage for their application as degradable implants. The candidate materials for such application should have mechanical properties ideally close to those of 316L stainless steel which is the gold standard material for stent application in order to provide mechanical support to diseased arteries. Non-toxicity of the metal itself and its degradation products is another requirement as the material is absorbed by blood and cells. Based on the mentioned requirements, iron-based and magnesium-based alloys have been the investigated candidates for biodegradable stents. This article reviews the recent developments in the design and evaluation of metallic materials for biodegradable stents. It also introduces the new metallurgical processes which could be applied for the production of metallic biodegradable stents and their effect on the properties of the produced metals.

  3. Everolimus-eluting stents: update on current clinical studies

    Directory of Open Access Journals (Sweden)

    Allocco DJ

    2011-07-01

    Full Text Available Dominic J Allocco, Anita A Joshi, Keith D DawkinsBoston Scientific Corporation, Natick, MA, USAAbstract: Everolimus-eluting stents (EES have become the most commonly implanted coronary stents worldwide. This review describes and analyzes the clinical data supporting the use of EES, focusing primarily on published, randomized, controlled trials. Everolimuseluting stents have been shown to have less restenosis, stent thrombosis, and periprocedural myocardial infarction compared with earlier generation paclitaxel-eluting stents (PES. Lower rates of adverse events for EES compared with PES were generally seen in all subgroups, with the notable exception of patients with diabetes mellitus. There have been fewer, randomized, clinical trials comparing EES with either sirolimus-eluting stents or zotarolimus-eluting stents, although very good results with EES have been observed in the trials that have been performed. Recent clinical trial data suggest that this excellent safety and efficacy profile is maintained in a next-generation EES designed to have improved mechanical properties and radiopacity.Keywords: drug-eluting stents, everolimus, Xience V, Promus, Promus ElementVideo Abstract:  http://dvpr.es/allocco  

  4. 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.

  5. 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.

  6. 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.

  7. Coronary bifurcation lesions treated with simple or complex stenting

    DEFF Research Database (Denmark)

    Behan, Miles W; Holm, Niels R; de Belder, Adam J;

    2016-01-01

    AIMS: Randomized trials of coronary bifurcation stenting have shown better outcomes from a simple (provisional) strategy rather than a complex (planned two-stent) strategy in terms of short-term efficacy and safety. Here, we report the 5-year all-cause mortality based on pooled patient-level data...

  8. Construction of a fucoidan/laminin functional multilayer to direction vascular cell fate and promotion hemocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Changrong; Wang, Yan; Su, Hong; Yang, Ping; Huang, Nan [Key Laboratory of Advanced Materials Technology of Ministry of Education, Department of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China); Maitz, Manfred F. [Leibniz Institute of Polymer Research Dresden, Max Bergmann Center of Biomaterials Dresden, Dresden 01069 (Germany); Zhao, Anshan [Key Laboratory of Advanced Materials Technology of Ministry of Education, Department of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031 (China)

    2016-07-01

    Surface biofunctional modification of cardiovascular stents is a versatile approach to reduce the adverse effects after implantation. In this work, a novel multifunctional coating was fabricated by coimmobilization of the sulfated polysaccharide of brown algae fucoidan and laminin to biomimic the vascular intimal conditions in order to support rapid endothelialization, prevent restenosis and improve hemocompatibility. The surface properties of the coating such as hydrophilicity, bonding density of biomolecules and stability were evaluated and optimized. According to the biocompatibility tests, the fucoidan/laminin multilayer coated surface displayed less platelet adhesion with favorable anticoagulant property. In addition, the fucoidan/laminin complex showed function to selectively regulate vascular cells growth behavior. The proliferation of endothelial cells (ECs) on the fucoidan/laminin biofunctional coating was significantly promoted. For the smooth muscle cells (SMCs), inhibitory effects on cell adhesion and proliferation were observed. In conclusion, the fucoidan/laminin biofunctional coating was successfully fabricated with desirable anticoagulant and endothelialization properties which show a promising application in the vascular devices such as vascular stents or grafts surface modification. - Highlights: • Construction of fucoidan/laminin functional multilayer to biomimic the basement membrane of vascular • The fucoidan/laminin complex demonstrates anti-coagulation property. • The fucoidan/laminin complex can selectively regulate EC and SMC growth behavior to prevent restenosis.

  9. A Dual Expandable Nitinol Stent: The Long-term Results in Patients with Malignant Gastroduodenal Strictures

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hee; Jung, Gyoo Sik; Oh, Kyeung Seung [Kosin University College of Medicine, Busan (Korea, Republic of)

    2009-12-15

    We wanted to evaluate the long-term results of a dual expandable nitinol stent for the palliative treatment of malignant gastroduodenal strictures. The dual stent consists of two stents; an outer partially nylon covered stent and an inner bare nitinol stent. The outer stent was placed into the stricture and this was followed by coaxial placement of the inner bare stent. Using fluoroscopic guidance, dual expandable stents were placed in 86 patients with inoperable malignant gastroduodenal strictures. The technical and clinical success, the complication, survival and the stent patency were evaluated during the follow-up period. Stent placement was technically successful in 83 of the 86 patients. After stent placement, 74 of the 85 patients showed improvement of their symptoms. During the mean follow-up period of 133 days, 24 patients (28%) developed recurrent symptoms due to incomplete expansion (n=1), stent migration (n=4), food impaction (n=2), granulation tissue formation (n=2), tumor overgrowth (n=6), tumor ingrowth (n=1) and stent collapse (n=8). Eleven of them were successfully treated by means of placing a second stent. The median period of stent patency was 212 days (mean, 299 days). The 30-day, 60-day, 90-day and 180-day patency rates were 93%, 84%, 81% and 53%, respectively. The dual expandable nitinol stent seems to be effective for the palliation of malignant gastroduodenal strictures

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Design and modeling balloon-expandable coronary stent for manufacturability

    Science.gov (United States)

    Suryawan, D.; Suyitno

    2017-02-01

    Coronary artery disease (CAD) is a disease that caused by narrowing of the coronary artery. The narrowing coronary artery is usually caused by cholesterol-containing deposit (plaque) which can cause a heart attack. CAD is the most common cause mortality in Indonesia. The commonly CAD treatment use the stent to opens or alleviate the narrowing coronary artery. In this study, the stent design is optimized for the manufacturability. Modeling is used to determine the free stent expansion due to applied pressure in the inner surface of the stent. The stress distribution, outer diameter change, and dogboning phenomena are investigated in the simulation. The result of modeling and simulating was analyzed and used to optimize the stent design before it is manufactured using EDM (Electric Discharge Machine) in the next research.

  15. An Indwelling Ureteral Stent Forgotten for Over 12 Years

    Science.gov (United States)

    Bidnur, Samir; Huynh, Melissa; Hoag, Nathan

    2016-01-01

    Abstract Ureteral stents are one of the most commonly used urologic devices with the purpose of establishing and maintaining ureteral patency. They are also associated with a number of complications including infection, migration, stent-related symptoms, and encrustation, leading to lithiasis. Prolonged stent dwell time is associated with a greater degree of these complications. We present the case of a 36-year-old man who presented with a severely encrusted ureteral stent that had been placed 12.5 years prior for an obstructive left-sided ureteral stone and was lost to follow-up. The patient underwent a combination of percutaneous nephrolithomy, cystolitholapaxy, and ureteroscopy to remove the stent and associated 1.7 cm renal pelvic stone and 4.1 cm bladder stone, necessitating two operative sittings to render him stone free. PMID:27579442

  16. 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

    Aims: The use of drug-eluting stents (DES) in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS) is controversial and not yet endorsed in clinical guidelines. Methods and results: This was an a priori planned post hoc analysis involving 754 NSTE-ACS patients from the random...

  17. Endoscopic removal of a proximal urethral stent using a holmium laser: Case report and literature review

    Directory of Open Access Journals (Sweden)

    Francisco Botelho

    2012-01-01

    Full Text Available Urethral stents were initially developed for the management of urethral strictures and obstructive voiding disorders in select patients. Urethral stent complications are common and may require stent explantation, which is often quite challenging. We present our experience with endoscopic removal of an encrusted UroLume proximal urethral stent in a 72-year-old male using a holmium laser. The literature on various management options and outcomes for urethral stent removal is reviewed. Endoscopic removal of proximal urethral stents is feasible and safe and should be considered as the primary treatment option in patients requiring stent extraction.

  18. Two-year outcome after Xpert stent implantation for treating below the knee lesions in critical limb ischemia.

    Science.gov (United States)

    Bosiers, Marc; Lioupis, Christos; Deloose, Koen; Verbist, Jürgen; Peeters, Patrick

    2009-01-01

    We investigated the efficacy of Xpert (Abbott Vascular, Abbott Park, IL) nitinol stents for the treatment of infrapopliteal lesions in patients with Critical Limb Ischemia (CLI). Between May 2005 and November 2007, 94 CLI patients (70 male, mean age 73.5 years) received 134 Xpert stents in 102 limbs. Seventy-nine patients (71.2%) were scored as Rutherford Category 4, 31 patients (27.9%) as Category 5 and 1 patient (0.9%) as Category 6. Primary endpoint of this study was defined as 2-year duplex derived primary patency. Secondary endpoints were 2-year limb salvage rate and the absence of reintervention after the index procedure. Kaplan Meier analysis reported 2-year primary patency and limb salvage rates of 54.4% and 90.8%, respectively. Stratification by lesion location did not reveal any significant differences in 2-year primary patency rates in proximal and distal below the knee lesions. Our results suggest that treatment with nitinol Xpert stents can be considered effective for treating CLI patients, with satisfying patency outcome.

  19. Effect of force-induced mechanical stress at the coronary artery bifurcation stenting: Relation to in-stent restenosis

    Science.gov (United States)

    Lee, Cheng-Hung; Jhong, Guan-Heng; Hsu, Ming-Yi; Liu, Shih-Jung; Wang, Chao-Jan; Hung, Kuo-Chun

    2014-05-01

    The deployment of metallic stents during percutaneous coronary intervention has become common in the treatment of coronary bifurcation lesions. However, restenosis occurs mostly at the bifurcation area even in present era of drug-eluting stents. To achieve adequate deployment, physicians may unintentionally apply force to the strut of the stents through balloon, guiding catheters, or other devices. This force may deform the struts and impose excessive mechanical stresses on the arterial vessels, resulting in detrimental outcomes. This study investigated the relationship between the distribution of stress in a stent and bifurcation angle using finite element analysis. The unintentionally applied force following stent implantation was measured using a force sensor that was made in the laboratory. Geometrical information on the coronary arteries of 11 subjects was extracted from contrast-enhanced computed tomography scan data. The numerical results reveal that the application of force by physicians generated significantly higher mechanical stresses in the arterial bifurcation than in the proximal and distal parts of the stent (post hoc P stenting, and potential mechanisms of in-stent restenosis, along with their relationship with bifurcation angle.

  20. Type D personality predicts death or myocardial infarction after bare metal stent or sirolimus-eluting stent implantation

    DEFF Research Database (Denmark)

    Pedersen, Susanne S.; Lemos, Pedro A; van Vooren, Priya R;