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Sample records for staccato stent strut

  1. Flow Characteristics Near to Stent Strut Configurations on Femoropopliteal Artery

    Science.gov (United States)

    Paisal, Muhammad Sufyan Amir; Fadhil Syed Adnan, Syed; Taib, Ishkrizat; Ismail, Al Emran; Kamil Abdullah, Mohammad; Nordin, Normayati; Seri, Suzairin Md; Darlis, Nofrizalidris

    2017-08-01

    Femoropopiteal artery stenting is a common procedure suggested by medical expert especially for patient who is diagnosed with severe stenosis. Many researchers reported that the growth of stenosis is significantly related to the geometry of stent strut configuration. The different shapes of stent geometry are presenting the different flow pattern and re-circulation in stented femoropopliteal artery. The blood flow characteristics near to the stent geometry are predicted for the possibility of thrombosis and atherosclerosis to be formed as well as increase the growth of stenosis. Thus, this study aims to determine the flow characteristic near to stent strut configuration based on different hemodynamic parameters. Three dimensional models of stent and simplified femoropopliteal artery are modelled using computer aided design (CAD) software. Three different models of stent shapes; hexagon, circle and rectangle are simulated using computational fluid dynamic (CFD) method. Then, parametric study is implemented to predict the performance of stent due to hemodynamic differences. The hemodynamic parameters considered are pressure, velocity, low wall shear stress (WSSlow) and wall shear stress (WSS). From the observation, flow re-circulation has been formed for all simulated stent models which the proximal region shown the severe vortices. However, rectangular shape of stent strut (Type P3) shows the lowest WSSlow and the highest WSS between the range of 4 dyne/cm2 and 70 dyne/cm2. Stent Type P3 also shows the best hemodynamic stent performance as compare to others. In conclusion, Type P3 has a favourable result in hemodynamic stent performance that predicted less probability of thrombosis and atherosclerosis to be formed as well as reduces the growth of restenosis.

  2. Impact of stent strut design in metallic stents and biodegradable scaffolds.

    Science.gov (United States)

    Foin, Nicolas; Lee, Renick D; Torii, Ryo; Guitierrez-Chico, Juan Luis; Mattesini, Alessio; Nijjer, Sukhjinder; Sen, Sayan; Petraco, Ricardo; Davies, Justin E; Di Mario, Carlo; Joner, Michael; Virmani, Renu; Wong, Philip

    2014-12-20

    Advances in the understanding of healing mechanisms after stent implantation have led to the recognition of stent strut thickness as an essential factor affecting re-endothelialization and overall long term vessel healing response after Percutaneous Coronary Interventions (PCI). Emergence of Drug-eluting stents (DESs) with anti-proliferative coating has contributed to reducing the incidence of restenosis and Target Lesion Revascularization (TVR), while progress and innovations in stent materials have in the meantime facilitated the design of newer platforms with more conformability and thinner struts, producing lesser injury and improving integration into the vessel wall. Recent advances in biodegradable metal and polymer materials now also allow for the design of fully biodegradable platforms, which are aimed at scaffolding the vessel only temporarily to prevent recoil and constrictive remodeling of the vessel during the initial period required, and are then progressively resorbed thereby avoiding the drawback of leaving an unnecessary implant permanently in the vessel. The aim of this article is to review recent evolution in stent material and stent strut design while understanding their impact on PCI outcomes. The article describes the different metallic alloys and biodegradable material properties and how these have impacted the evolution of stent strut thickness and ultimately outcomes in patients. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  3. Optical coherence tomography at follow-up after percutaneous coronary intervention: relationship between procedural dissections, stent strut malapposition and stent healing

    DEFF Research Database (Denmark)

    Radu, Maria; Jørgensen, Erik; Kelbæk, Henning

    2011-01-01

    To analyse the relationship between strut apposition as visualised with optical coherence tomography (OCT) at follow-up and clinical and procedural characteristics at stent implantation, and to examine the relationship between strut apposition and stent healing.......To analyse the relationship between strut apposition as visualised with optical coherence tomography (OCT) at follow-up and clinical and procedural characteristics at stent implantation, and to examine the relationship between strut apposition and stent healing....

  4. The relationship between post-stent strut apposition and follow-up strut coverage assessed by a contour plot optical coherence tomography analysis.

    Science.gov (United States)

    Kim, Jung-Sun; Ha, Jinyong; Kim, Byeong-Keuk; Shin, Dong-Ho; Ko, Young-Guk; Choi, Donghoon; Jang, Yangsoo; Hong, Myeong-Ki

    2014-06-01

    This study sought to evaluate the relationship between post-stent strut apposition and follow-up strut coverage using contour plot optical coherence tomographic analysis. Tracking the fate of interested regions of struts at different time points has not been investigated. Post-intervention and 6-month follow-up optical coherence tomographic evaluations were performed in 82 patients treated with biolimus- (n = 37) or sirolimus-eluting stents (n = 45). Post-stent apposition was classified as embedded, apposed, or malapposed. For volumetric stent evaluation, the post-intervention strut-artery distance and the neointimal thickness at follow-up were measured as a function of the circumferential arc length and longitudinal stent length. Computer-generated contour plots of the strut-artery distance and neointimal thickness were compared. The percentages of embedded and malapposed struts after intervention were 1.8% (Interquartile range [IQR]: 0.6% to 6.2%) and 2.3% (IQR: 0.5% to 5.2%), respectively. The percentages of uncovered and malapposed struts at 6 months were 16.0% (IQR: 7.4% to 33.3%) and 0% (IQR: 0% to 0.7%), respectively. The percentage of uncovered struts at 6 months varied significantly with post-stent strut apposition (0% [IQR: 0% to 11.4%] in embedded, 16.3% [IQR: 8.1% to 31.3%] in apposed, and 26.8% [IQR: 0% to 56.3%] in malapposed, p < 0.001 for all pairwise comparisons). In lesions without tissue prolapse, embedded struts were all covered (100% covered struts) compared with those with tissue prolapse (76.8% covered, p < 0.001). The optical coherence tomography-guided optimization of stent strut apposition enhances strut coverage at follow-up. This comprehensive method for evaluating strut apposition may provide more useful information to understanding the serial changes in strut coverage. (Neointimal Coverage After Implantation of Biolimus Eluting Stent With Biodegradable Polymer: Optical Coherence Tomographic Assessment According to the Treatment of

  5. Automated measurement of stent strut coverage in intravascular optical coherence tomography

    Science.gov (United States)

    Ahn, Chi Young; Kim, Byeong-Keuk; Hong, Myeong-Ki; Jang, Yangsoo; Heo, Jung; Joo, Chulmin; Seo, Jin Keun

    2015-02-01

    Optical coherence tomography (OCT) is a non-invasive, cross-sectional imaging modality that has become a prominent imaging method in percutaneous intracoronary intervention. We present an automated detection algorithm for stent strut coordinates and coverage in OCT images. The algorithm for stent strut detection is composed of a coordinate transformation from the polar to the Cartesian domains and application of second derivative operators in the radial and the circumferential directions. Local region-based active contouring was employed to detect lumen boundaries. We applied the method to the OCT pullback images acquired from human patients in vivo to quantitatively measure stent strut coverage. The validation studies against manual expert assessments demonstrated high Pearson's coefficients ( R = 0.99) in terms of the stent strut coordinates, with no significant bias. An averaged Hausdorff distance of < 120 μm was obtained for vessel border detection. Quantitative comparison in stent strut to vessel wall distance found a bias of < 12.3 μm and a 95% confidence of < 110 μm.

  6. Delayed coverage in malapposed and side-branch struts with respect to well-apposed struts in drug-eluting stents: In vivo assessment with optical coherence tomography

    NARCIS (Netherlands)

    J.L. Gutiérrez-Chico; E.S. Regar (Eveline); E. NüesC.H. (Eveline); T. Okamura (Takayuki); J.J. Wykrzykowska (Joanna); C. di Mario (Carlo); S.W. Windecker (Stephan); G.A. van Es (Gerrit Anne); P. Gobbens (Pierre); P. Jüni (Peter); P.W.J.C. Serruys (Patrick)

    2011-01-01

    textabstractBackground-Pathology studies on fatal cases of very late stent thrombosis have described incomplete neointimal coverage as common substrate, in some cases appearing at side-branch struts. Intravascular ultrasound studies have described the association between incomplete stent apposition

  7. Stents Eluting 6-Mercaptopurine Reduce Neointima Formation and Inflammation while Enhancing Strut Coverage in Rabbits.

    Directory of Open Access Journals (Sweden)

    Matthijs S Ruiter

    Full Text Available The introduction of drug-eluting stents (DES has dramatically reduced restenosis rates compared with bare metal stents, but in-stent thrombosis remains a safety concern, necessitating prolonged dual anti-platelet therapy. The drug 6-Mercaptopurine (6-MP has been shown to have beneficial effects in a cell-specific fashion on smooth muscle cells (SMC, endothelial cells and macrophages. We generated and analyzed a novel bioresorbable polymer coated DES, releasing 6-MP into the vessel wall, to reduce restenosis by inhibiting SMC proliferation and decreasing inflammation, without negatively affecting endothelialization of the stent surface.Stents spray-coated with a bioresorbable polymer containing 0, 30 or 300 μg 6-MP were implanted in the iliac arteries of 17 male New Zealand White rabbits. Animals were euthanized for stent harvest 1 week after implantation for evaluation of cellular stent coverage and after 4 weeks for morphometric analyses of the lesions.Four weeks after implantation, the high dose of 6-MP attenuated restenosis with 16% compared to controls. Reduced neointima formation could at least partly be explained by an almost 2-fold induction of the cell cycle inhibiting kinase p27Kip1. Additionally, inflammation score, the quantification of RAM11-positive cells in the vessel wall, was significantly reduced in the high dose group with 23% compared to the control group. Evaluation with scanning electron microscopy showed 6-MP did not inhibit strut coverage 1 week after implantation.We demonstrate that novel stents coated with a bioresorbable polymer coating eluting 6-MP inhibit restenosis and attenuate inflammation, while stimulating endothelial coverage. The 6-MP-eluting stents demonstrate that inhibition of restenosis without leaving uncovered metal is feasible, bringing stents without risk of late thrombosis one step closer to the patient.

  8. Biological effect of microengineered grooved stents on strut healing: a randomised OCT-based comparative study in humans

    Science.gov (United States)

    Vesga, Boris; Hernandez, Hector; Higuera, Sergio; Gasior, Pawel; Echeveri, Dario; Delgado, Juan A; Dager, Antonio; Arana, Camilo; Simonton, Charles; Maehara, Akiko; Palmaz, Julio; Granada, Juan F

    2017-01-01

    Objective To evaluate the biological effect of microengineered stent grooves (MSG) on early strut healing in humans by performing optical coherence tomography (OCT) analysis 3 weeks following the implantation. Background In the experimental setting, MSG accelerate endothelial cell migration and reduce neointimal proliferation compared with bare metal stent (BMS). Methods A total of 37 patients undergoing percutaneous coronary intervention with de novo coronary lesions were randomly assigned to either MSG (n=19) or an identical BMS controls (n=18). All patients underwent OCT imaging at 3 weeks. A total of 7959 struts were included in the final analysis. Results At 3 weeks following stent implantation, almost all struts analysed (~97%) had evidence of tissue coverage. The percentage of partially covered struts was comparable between both groups. However, the percentage of fully embedded struts was higher in the BMS group (81.22%, 49.75–95.52) compared with the MSG group (74.21%, 58.85–86.38). The stent-level analysis demonstrated reduction in neointimal formation (neointimal hyperplasia area and volume reduction of ~14% and ~19%, respectively) in the MSG versus the BMS group. In the strut-level analysis, an even greater reduction (~22% in neointimal thickness) was seen in the MSG group. Layered neointimal was present in ~6% of the OCT frames in the BMS group while it was not present in the MSG group. Conclusions MSG induced a more homogeneous and predictable pattern of surface healing in the early stages following stent implantation. The biological effect of MSG on stent healing has the potential to improve the safety profile of current generation drug-eluting stents. Classifications BMS, OCT, clinical trials. PMID:28674616

  9. Satisfactory arterial repair 1 year after ultrathin strut biodegradable polymer sirolimus-eluting stent implantation: an angioscopic observation.

    Science.gov (United States)

    Ishihara, Takayuki; Awata, Masaki; Iida, Osamu; Fujita, Masashi; Masuda, Masaharu; Okamoto, Shin; Nanto, Kiyonori; Kanda, Takashi; Tsujimura, Takuya; Uematsu, Masaaki; Mano, Toshiaki

    2018-01-15

    The ultrathin strut biodegradable polymer sirolimus-eluting stent (Orsiro, O-SES) exhibits satisfactory clinical outcomes. However, no report to date has documented the intravascular status of artery repair after O-SES implantation. We examined 5 O-SES placed in 4 patients (age 65 ± 12 years, male 75%) presenting with stable angina pectoris due to de novo lesions in native coronary arteries. Coronary angioscopy was performed immediately after percutaneous coronary intervention and 1 year later. Angioscopic images were analyzed to determine the following: (1) dominant grade of neointimal coverage (NIC) over the stent; (2) maximum yellow plaque grade; and (3) existence of thrombus. Yellow plaque grade was evaluated both immediately after stent implantation and at the time of follow-up observation. The other parameters were evaluated at the time of follow-up examination. NIC was graded as: grade 0, stent struts exposed; grade 1, struts bulging into the lumen, although covered; grade 2, struts embedded in the neointima, but translucent; grade 3, struts fully embedded and invisible. Yellow plaque severity was graded as: grade 0, white; grade 1, light yellow; grade 2, yellow; and grade 3, intensive yellow. Angioscopic findings at 1 year demonstrated the following: dominant NIC grade 1, grade 2, and grade 3 in 1, 2, and 2 stents, respectively; all stents were covered to some extent; focal thrombus adhesion was observed in only 1 stent. Yellow plaque grade did not change from immediately after stent implantation to follow-up. O-SES demonstrated satisfactory arterial repair 1 year after implantation.

  10. Intra- and interobserver reliability and intra-catheter reproducibility using frequency domain optical coherence tomography for the evaluation of morphometric stent parameters and qualitative assessment of stent strut coverage

    DEFF Research Database (Denmark)

    Antonsen, Lisbeth; Thayssen, Per; Junker, Anders

    2015-01-01

    to investigate the intra- and interobserver reliability, as well as the intra-catheter reproducibility of quantitative FD-OCT-assessment of morphometric stent parameters and qualitative FD-OCT-evaluation of strut coverage in 10 randomly selected 6-month follow-up Nobori® biolimus-eluting stents (N-BESs). METHODS...... in another 10 N-BESs (219 CSAs and 1860 struts) were independently assessed by one of the analysts. RESULTS: The intraobserver variability with regard to relative difference of mean luminal area and mean stent area at the CSA-level was very low: 0.1%±1.4% and 0.5%±3.2%. Interobserver variability also proved...... (CI): 0.88-0.93, pstented coronary segments, and for qualitative assessment of strut coverage....

  11. Solving the Issue of Restenosis After Stenting of Intracranial Stenoses: Experience with Two Thin-Strut Drug-Eluting Stents (DES)—Taxus Element™ and Resolute Integrity™

    Energy Technology Data Exchange (ETDEWEB)

    Kurre, Wiebke, E-mail: wiebke.kurre@gmx.de; Aguilar-Pérez, Marta [Klinikum Stuttgart, Klinik für Diagnostische und Interventionelle Neuroradiologie (Germany); Fischer, Sebastian [Universitätsklinikum Knappschaftskrankenhaus Bochum GmbH, Institut für Diagnostische und Interventionelle Radiologie, Neuroradiologie und Nuklearmedizin (Germany); Arnold, Guy [Klinikverbund Südwest, Klinikum Sindelfingen, Klinik für Neurologie (Germany); Schmid, Elisabeth; Bäzner, Hansjörg [Klinikum Stuttgart, Klinik für Neurologie (Germany); Henkes, Hans [Klinikum Stuttgart, Klinik für Diagnostische und Interventionelle Neuroradiologie (Germany)

    2015-06-15

    PurposeThin-strut, flexible DES are suitable for intracranial stenting and may improve long-term vessel patency. The purpose of this study was to report our experience with two new-generation DES for the treatment of intracranial atherosclerotic disease.Patients and MethodsWe retrospectively reviewed all patients treated with Taxus Element™ or Resolute Integrity™ stent for an intracranial atherosclerotic stenosis between March 2011 and August 2013. Technical success was defined as the ability to deploy the device at the desired location and reduce the degree of stenosis below 50 %. All procedure-related strokes were recorded. Control angiography was scheduled after 6 weeks, 3, 6, and 12 months and yearly thereafter. A luminal narrowing ≥50 % was regarded as a restenosis. Stroke recurrence in the territory of the treated artery was reported.ResultsIn the defined period we treated 101 patients harboring 117 intracranial stenoses. The procedure was successful in 100 (85.5 %) lesions. Procedure-related strokes occurred in 10 (9.9 %) patients with a permanent morbidity in 3 (3.0 %). Follow-up angiography was available for 83 of 100 (83.0 %) successfully treated lesions with an average of 355 days (IQR 153–482 days). Three (3.6 %) asymptomatic restenoses were detected. All occurred after treatment with Resolute Integrity™, none after Taxus Element™ (p = 0.059). New strokes in the territory of the treated artery were encountered in 2 (2.6 %) occasions.ConclusionThin-strut DES improve long-term patency and reduce the risk of subsequent stroke. Differences between devices may exist. Feasibility is comparable to bare-metal balloon-mounted stents and procedure-related strokes occurred within the expected range.

  12. Initial and mid-term results of a 4F compatible self-expanding low strut profile nitinol stent in the superficial femoral artery

    International Nuclear Information System (INIS)

    Muehlenbruch, G.; Brock, H.; Das, M.; Hohl, C.; Mahnken, A.H.; Wildberger, J.; Guenther, R.W.; Haage, P.

    2007-01-01

    Purpose: To evaluate the initial and mid-term results of a new self-expanding low strut profile nitinol stent for treatment of atherosclerotic lesions stenoses and occlusions in the superficial femoral artery (SFA). Materials and Methods: In 8 patients (4 male, 4 female, mean age 74.8 ± 8.8 years) with SFA lesions and non-satisfying results after PTA treatment alone, 10 self-expanding nitinol Xpert stents were deployed via a 4 F sheath. Stent characteristics and handling were graded by the interventionalist. Fontaine classification, duplex flow measurements and ankle brachial index (ABI) at rest and stress were taken prior and one day after stent placement. Patients were followed 3, 6 and 12 months after the procedure obtaining the same parameters at each appointment. Results: Initial stent treatment was successful in all patients. Stent handling and positioning were rated very good and safe. All patients improved clinically by at least one Fontaine stage (range before treatment: stage IIb to IV). The mean ABI at rest (stress) improved initially from 0.68 (0.70) to 1.07 (0.99). During a mean follow-up period of 8.3 months no case of clinically relevant in-stent stenosis was observed with stable values of ABI at rest and stress. (orig.)

  13. 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

    formation of this new tissue, primarily consisting of VSMCs of the synthetic phenotype and their subsequent extracellular matrix, is the sole causation of in-stent restenosis since the stent serves to prevent elastic recoil and negative remodeling. This doctoral research program is focused on endovascular stent biomaterials science and engineering. Overall, this doctoral project is founded on the hypothesis that smooth muscle cell hyperplasia, as an important causative factor for vascular restenosis following endovascular stent deployment, is triggered by the various effects of stent strut contact on the vessel wall including contact forces and material biocompatibility. In this program, a dynamic in vitro model of a stented blood vessel aimed at evaluating the effect of stent strut material selection, and surface coating on smooth muscle cell response was developed. The in vitro stented artery model was validated through the proliferation of VSMC in contact with stent struts. Additionally, it was demonstrated that, with respect to known biocompatible materials such as Nitinol and 316L stainless steel, DNA synthesis and alpha-actin expression, as indicators of VSMC phenotype, are independent of stent material composition. Furthermore, hydroxyapatite was shown to be a biocompatible stent surface coating with acceptable post-strain integrity. This coating was shown in a feasibility study to be capable of serving as a favorable drug delivery platform able to reliably deliver locally therapeutic doses of bisphosphonates, such as alendronate, to control VSMC proliferation in an in vitro model of a stented blood vessel. This stent coating/drug combination may be effective for reducing restenosis as a result of VSMC hyperplasia in vivo.

  14. Serial optical coherence tomography assessment of malapposed struts after everolimus-eluting stent implantation. A subanalysis from the HEAL-EES study

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, Kohki [Cardiology Department, Cardiovascular Institute, Hospital Clínic, Institut d' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona (Spain); Otsuki, Shuji [Division of Cardiology, Teikyo University Hospital, Tokyo (Japan); Giacchi, Giuseppe; Ortega-Paz, Luis [Cardiology Department, Cardiovascular Institute, Hospital Clínic, Institut d' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona (Spain); Shiratori, Yoshitaka [Division of Cardiology, Teikyo University Hospital, Tokyo (Japan); Freixa, Xavier; Martín-Yuste, Victoria; Masotti, Mónica; Sabaté, Manel [Cardiology Department, Cardiovascular Institute, Hospital Clínic, Institut d' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona (Spain); Brugaletta, Salvatore, E-mail: sabrugal@clinic.ub.es [Cardiology Department, Cardiovascular Institute, Hospital Clínic, Institut d' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona (Spain)

    2017-01-15

    Background: Incomplete stent apposition (ISA) is related to stent thrombosis, which is a serious adverse event. We aim to assess the time-course of ISA after 2nd generation everolimus-eluting stent (EES) implantation. Methods: In HEAL-EES study, we enrolled 36 patients who underwent percutaneous coronary intervention (PCI) with EES. OCT imaging was performed at baseline and follow-up. Patients were randomized 1:1:1 into 3 groups according to the time in which follow-up was performed: group A (6-month), group B (9-month), and group C (12-month). In this subanalysis, patients who had ISA segments at baseline and/or follow-up OCT were analyzed. Result: At baseline, among 41 lesions in 36 patients, 20 lesions in 18 patients had ISA segments and were analyzed. At baseline, there were 3.0% ISA struts in group A (n = 8), 2.8% in group B (n = 4), and 4.5% in group C (n = 8). At follow-up, ISA struts were present in 0.09%, 0.16% and 0.64%; respectively in groups A, B, and C. At follow-up, there was a significant decrease in the frequency of ISA: group A 3.0% vs. 0.09% (p < 0.001), group B 2.8% vs. 0.16% (p < 0.001), and group C 4.5% vs. 0.64% (p < 0.001). In group A, there was one late acquired ISA at follow-up. Conclusions: In patients undergoing 2nd generation EES implantation, area of acute ISA assessed by OCT, was almost resolved at 6-month follow-up. - Highlights: • Time-course of incomplete stent apposition of everolimus-eluting stent was assessed. • Serial optical coherence tomography images at baseline and follow-up were evaluated. • Acute incomplete stent apposition was almost resolved as early as at 6 months.

  15. Intra- and interobserver reliability and intra-catheter reproducibility using frequency domain optical coherence tomography for the evaluation of morphometric stent parameters and qualitative assessment of stent strut coverage

    International Nuclear Information System (INIS)

    Antonsen, Lisbeth; Thayssen, Per; Junker, Anders; Veien, Karsten Tange; Hansen, Henrik Steen; Hansen, Knud Nørregaard; Hougaard, Mikkel; Jensen, Lisette Okkels

    2015-01-01

    Purpose: Frequency-domain optical coherence tomography (FD-OCT) is a high-resolution imaging tool (~ 10–15 μm), which enables near-histological in-vivo images of the coronary vessel wall. The use of the technique is increasing, both for research- and clinical purposes. This study sought to investigate the intra- and interobserver reliability, as well as the intra-catheter reproducibility of quantitative FD-OCT-assessment of morphometric stent parameters and qualitative FD-OCT-evaluation of strut coverage in 10 randomly selected 6-month follow-up Nobori® biolimus-eluting stents (N-BESs). Methods: Ten N-BESs (213 cross sectional areas (CSAs) and 1897 struts) imaged with OCT 6 months post-implantation were randomly selected and analyzed by 2 experienced analysts, and the same 10 N-BESs were analyzed by one of the analysts 3 months later. Further, 2 consecutive pullbacks randomly performed in another 10 N-BESs (219 CSAs and 1860 struts) were independently assessed by one of the analysts. Results: The intraobserver variability with regard to relative difference of mean luminal area and mean stent area at the CSA-level was very low: 0.1% ± 1.4% and 0.5% ± 3.2%. Interobserver variability also proved to be low: − 2.1% ± 3.3% and 2.1% ± 4.6%, and moreover, very restricted intra-catheter variation was observed: 0.02% ± 6.8% and − 0.18% ± 5.2%. The intraobserver-, interobserver- and intra-catheter reliability for the qualitative evaluation of strut coverage was found to be: kappa (κ) = 0.91 (95% confidence interval (CI): 0.88–0.93, p < 0.01), κ = 0.88 (95% CI: 0.85–0.91, p < 0.01), and κ = 0.73 (95% CI: 0.68–0.78, p < 0.01), respectively. Conclusions: FD-OCT is a reproducible and reliable imaging tool for quantitative evaluation of stented coronary segments, and for qualitative assessment of strut coverage. - Highlights: • Frequency-domain optical coherence tomography (FD-OCT) is increasingly adopted in the catherization laboratories. • This

  16. Intra- and interobserver reliability and intra-catheter reproducibility using frequency domain optical coherence tomography for the evaluation of morphometric stent parameters and qualitative assessment of stent strut coverage

    Energy Technology Data Exchange (ETDEWEB)

    Antonsen, Lisbeth, E-mail: Lisbeth.antonsen@rsyd.dk; Thayssen, Per; Junker, Anders; Veien, Karsten Tange; Hansen, Henrik Steen; Hansen, Knud Nørregaard; Hougaard, Mikkel; Jensen, Lisette Okkels

    2015-12-15

    Purpose: Frequency-domain optical coherence tomography (FD-OCT) is a high-resolution imaging tool (~ 10–15 μm), which enables near-histological in-vivo images of the coronary vessel wall. The use of the technique is increasing, both for research- and clinical purposes. This study sought to investigate the intra- and interobserver reliability, as well as the intra-catheter reproducibility of quantitative FD-OCT-assessment of morphometric stent parameters and qualitative FD-OCT-evaluation of strut coverage in 10 randomly selected 6-month follow-up Nobori® biolimus-eluting stents (N-BESs). Methods: Ten N-BESs (213 cross sectional areas (CSAs) and 1897 struts) imaged with OCT 6 months post-implantation were randomly selected and analyzed by 2 experienced analysts, and the same 10 N-BESs were analyzed by one of the analysts 3 months later. Further, 2 consecutive pullbacks randomly performed in another 10 N-BESs (219 CSAs and 1860 struts) were independently assessed by one of the analysts. Results: The intraobserver variability with regard to relative difference of mean luminal area and mean stent area at the CSA-level was very low: 0.1% ± 1.4% and 0.5% ± 3.2%. Interobserver variability also proved to be low: − 2.1% ± 3.3% and 2.1% ± 4.6%, and moreover, very restricted intra-catheter variation was observed: 0.02% ± 6.8% and − 0.18% ± 5.2%. The intraobserver-, interobserver- and intra-catheter reliability for the qualitative evaluation of strut coverage was found to be: kappa (κ) = 0.91 (95% confidence interval (CI): 0.88–0.93, p < 0.01), κ = 0.88 (95% CI: 0.85–0.91, p < 0.01), and κ = 0.73 (95% CI: 0.68–0.78, p < 0.01), respectively. Conclusions: FD-OCT is a reproducible and reliable imaging tool for quantitative evaluation of stented coronary segments, and for qualitative assessment of strut coverage. - Highlights: • Frequency-domain optical coherence tomography (FD-OCT) is increasingly adopted in the catherization laboratories. • This

  17. Direct intrahepatic portocaval shunt creation via the inter-strut space of the inferior vena cava stent

    International Nuclear Information System (INIS)

    Tsauo, J.; Yu, Y.; Luo, X.; Wang, Z.; Liu, L.; Li, X.

    2014-01-01

    Highlights: • The feasibility of DIPS creation through an IVC stent was investigated. • DIPS creation through the IVC stent was successful in all four patients. • DIPS creation through the IVC stent is feasible

  18. Circumferential Stent Fracture: Novel Detection and Treatment with the Use of StentBoost

    OpenAIRE

    Ramegowda, Raghu T.; Chikkaswamy, Srinivas B.; Bharatha, Ashalatha; Radhakrishna, Jayashree; Krishnanaik, Geetha B.; Nanjappa, Manjunath C.; Panneerselvam, Arunkumar

    2012-01-01

    Circumferential stent fracture is extremely uncommon, and in rare cases, it can cause stent thrombosis. Recognizing stent fracture can be difficult on conventional fluoroscopy because of poor stent radiopacity. We found that StentBoost image acquisition yields improved visibility of stent struts, enabling the identification of stent fracture and the precise positioning of new stents over previously stented segments.

  19. Stent

    Science.gov (United States)

    ... Drugs & Supplements Videos & Tools Español You Are Here: Home → Medical Encyclopedia → Stent URL of this page: //medlineplus.gov/ency/article/002303.htm Stent To use the sharing features on this page, please enable JavaScript. A stent is a tiny tube placed into a hollow structure in your ...

  20. 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.

  1. STACCATO: a novel solution to supernova photometric classification with biased training sets

    Science.gov (United States)

    Revsbech, E. A.; Trotta, R.; van Dyk, D. A.

    2018-01-01

    We present a new solution to the problem of classifying Type Ia supernovae from their light curves alone given a spectroscopically confirmed but biased training set, circumventing the need to obtain an observationally expensive unbiased training set. We use Gaussian processes (GPs) to model the supernovae's (SN's) light curves, and demonstrate that the choice of covariance function has only a small influence on the GPs ability to accurately classify SNe. We extend and improve the approach of Richards et al. - a diffusion map combined with a random forest classifier - to deal specifically with the case of biased training sets. We propose a novel method called Synthetically Augmented Light Curve Classification (STACCATO) that synthetically augments a biased training set by generating additional training data from the fitted GPs. Key to the success of the method is the partitioning of the observations into subgroups based on their propensity score of being included in the training set. Using simulated light curve data, we show that STACCATO increases performance, as measured by the area under the Receiver Operating Characteristic curve (AUC), from 0.93 to 0.96, close to the AUC of 0.977 obtained using the 'gold standard' of an unbiased training set and significantly improving on the previous best result of 0.88. STACCATO also increases the true positive rate for SNIa classification by up to a factor of 50 for high-redshift/low-brightness SNe.

  2. Computational micromechanics of bioabsorbable magnesium stents.

    Science.gov (United States)

    Grogan, J A; Leen, S B; McHugh, P E

    2014-06-01

    Magnesium alloys are a promising candidate material for an emerging generation of absorbable metal stents. Due to its hexagonal-close-packed lattice structure and tendency to undergo twinning, the deformation behaviour of magnesium is quite different to that of conventional stent materials, such as stainless steel 316L and cobalt chromium L605. In particular, magnesium exhibits asymmetric plastic behaviour (i.e. different yield behaviours in tension and compression) and has lower ductility than these conventional alloys. In the on-going development of absorbable metal stents it is important to assess how the unique behaviour of magnesium affects device performance. The mechanical behaviour of magnesium stent struts is investigated in this study using computational micromechanics, based on finite element analysis and crystal plasticity theory. The plastic deformation in tension and bending of textured and non-textured magnesium stent struts with different numbers of grains through the strut dimension is investigated. It is predicted that, unlike 316L and L605, the failure risk and load bearing capacity of magnesium stent struts during expansion is not strongly affected by the number of grains across the strut dimensions; however texturing, which may be introduced and controlled in the manufacturing process, is predicted to have a significant influence on these measures of strut performance. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Strut elaboration in strut-and-tie model

    Directory of Open Access Journals (Sweden)

    Mohammad PANJEHPOUR

    2012-12-01

    Full Text Available The Strut-and-Tie Model (STM has been incorporated into the codes and standards because of its consistency and rationality since last decade. However, it has encountered few challenges whilst its implementation. The effective compressive strength of strut has been a complex issue among researchers since emergence of STM. This review serves as a base for future developments of STM. It addresses several ways towards enhancing our understanding of strut performance in the STM. It also throws up questions for further investigation of effective compressive strength of strut in the STM. This review is confined to the evaluation of strut effectiveness factor based on the available codes and standards particularly AASHTO LRFD and ACI 318-08. According to the example given in this paper, there is sometimes a marked difference of approximately 50% between strut effectiveness factor recommended by AASHTO LRFD and ACI 318-08. More broadly, research is needed to determine which of the complicated strut effectiveness factor recommended by AASHTO LRFD and the simple one recommended by ACI 318-08 is optimum.

  4. 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.

  5. Recurrence of Subacute Stent Thrombosis and In-Stent Restenosis during Five Months after Stent Implantation in the LAD. A Case Report.

    OpenAIRE

    島田, 弘英; 大和, 眞史; 櫻井, 俊平; 疋田, 博之; 池田, 修一

    2001-01-01

    A coronary stent was deployed in the left anterior descending artery of an 82-year-old woman with unstable angina.Recurrence of subacute stent thrombosis and in-stent restenosis occurred frequently during the five months after initial stent implantation.Balloon angioplasty and cutting balloon angioplasty failed to prevent these complications,but they ceased after re-stenting in the initial stent.In this case,tissue protrusion through the stent strut, deformation of the coil stent and inadequa...

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

    Energy Technology Data Exchange (ETDEWEB)

    Bonnema, Garret T; Barton, Jennifer K [College of Optical Sciences, University of Arizona, Tucson, AZ (United States); Cardinal, Kristen O' Halloran [Biomedical and General Engineering, California Polytechnic State University (United States); Williams, Stuart K [Cardiovascular Innovation Institute, University of Louisville, Louisville, KY 40292 (United States)], E-mail: barton@u.arizona.edu

    2008-06-21

    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 {mu}m, 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.

  7. Angiographic CT: in vitro comparison of different carotid artery stents-does stent orientation matter?

    Science.gov (United States)

    Lettau, Michael; Bendszus, Martin; Hähnel, Stefan

    2013-06-01

    Our aim was to evaluate the in vitro visualization of different carotid artery stents on angiographic CT (ACT). Of particular interest was the influence of stent orientation to the angiography system by measurement of artificial lumen narrowing (ALN) caused by the stent material within the stented vessel segment to determine whether ACT can be used to detect restenosis within the stent. ACT appearances of 17 carotid artery stents of different designs and sizes (4.0 to 11.0 mm) were investigated in vitro. Stents were placed in different orientations to the angiography system. Standard algorithm image reconstruction and stent-optimized algorithm image reconstruction was performed. For each stent, ALN was calculated. With standard algorithm image reconstruction, ALN ranged from 19.0 to 43.6 %. With stent-optimized algorithm image reconstruction, ALN was significantly lower and ranged from 8.2 to 18.7 %. Stent struts could be visualized in all stents. Differences in ALN between the different stent orientations to the angiography system were not significant. ACT evaluation of vessel patency after stent placement is possible but is impaired by ALN. Stent orientation of the stents to the angiography system did not significantly influence ALN. Stent-optimized algorithm image reconstruction decreases ALN but further research is required to define the visibility of in-stent stenosis depending on image reconstruction.

  8. Insidious strut fractures in a DeBakey-Surgitool aortic valve prosthesis.

    Science.gov (United States)

    Scott, S M; Sethi, G K; Paulson, D M; Takaro, T

    1978-04-01

    Recent reports of cage wear occurring in DeBakey-Surgitool aortic valve prostheses prompted us to examine with image intensification all our patients who have had this type of prosthesis implanted. One patient, who was asymptomatic, was discovered to have a prosthesis with two fractured struts. This patient's prosthetic valve was replaced successfully with a stented porcine heterograft prosthesis. Including the valve removed from this patient, 8 DeBakey-Surgitool aortic valves with structural defects have been reported to the manufacturer. In the absence of a catastrophic event, patients with valves having fractured or worn struts may be totally asymptomatic, and routine periodic roentgenographic examination may be the only way of detecting strut wear or fracture.

  9. An ovine in vivo framework for tracheobronchial stent analysis.

    Science.gov (United States)

    McGrath, Donnacha J; Thiebes, Anja Lena; Cornelissen, Christian G; O'Shea, Mary B; O'Brien, Barry; Jockenhoevel, Stefan; Bruzzi, Mark; McHugh, Peter E

    2017-10-01

    Tracheobronchial stents are most commonly used to restore patency to airways stenosed by tumour growth. Currently all tracheobronchial stents are associated with complications such as stent migration, granulation tissue formation, mucous plugging and stent strut fracture. The present work develops a computational framework to evaluate tracheobronchial stent designs in vivo. Pressurised computed tomography is used to create a biomechanical lung model which takes into account the in vivo stress state, global lung deformation and local loading from pressure variation. Stent interaction with the airway is then evaluated for a number of loading conditions including normal breathing, coughing and ventilation. Results of the analysis indicate that three of the major complications associated with tracheobronchial stents can potentially be analysed with this framework, which can be readily applied to the human case. Airway deformation caused by lung motion is shown to have a significant effect on stent mechanical performance, including implications for stent migration, granulation formation and stent fracture.

  10. Stent Coating Integrity of Durable and Biodegradable Coated Drug Eluting Stents.

    Science.gov (United States)

    Yazdani, Saami K; Sheehy, Alexander; Pacetti, Stephen; Rittlemeyer, Brandon; Kolodgie, Frank D; Virmani, Renu

    2016-10-01

    Coatings consisting of a polymer and drug are widely used in drug-eluting stents (DES) and are essential in providing programmable drug release kinetics. Among other factors, stent coating technologies can influence blood compatibility, affect acute and sub-acute healing, and potentially trigger a chronic inflammatory response. The aim of this study was to investigate the short-term (7 and 28 days) and long-term (90 and 180 days) coating integrity of the Xience Prime Everolimus-Eluting Stent (EES), Resolute Zotarolimus-Eluting Stent (ZES), Taxus Paclitaxel-Eluting Stent (PES), and Nobori Biolimus A9-Eluting Stent (BES) in a rabbit ilio-femoral stent model. Stented arteries (n = 48) were harvested and the tissue surrounding the implanted stents digested away with an enzymatic solution. Results demonstrated that the majority of struts of EES were without any coating defects with a few struts showing minor defects. Similarly, for the ZES, most of the struts were without coating defects at all time points except at 180 days. The majority of PES demonstrated mostly webbing and uneven coating. In the BES group, the majority of strut coating showed polymer cracking. Overall, the EES and ZES had fewer coating defects than the PES and BES. Coating defects, however increase over time for the ZES, whereas the percent of coating irregularities remained constant for the EES. These results provide, for the first time, a comparison of the long-term durability of these drug-eluting stent coatings in vivo. © 2016, Wiley Periodicals, Inc.

  11. [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

  12. Magnetizable stent-grafts enable endothelial cell capture

    Energy Technology Data Exchange (ETDEWEB)

    Tefft, Brandon J. [Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States); Uthamaraj, Susheil [Division of Engineering, Mayo Clinic, Rochester, MN (United States); Harburn, J. Jonathan [School of Medicine, Pharmacy and Health, Durham University, Stockton-on-Tees (United Kingdom); Hlinomaz, Ota [Department of Cardioangiology, St. Anne' s University Hospital, Brno (Czech Republic); Lerman, Amir [Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States); Dragomir-Daescu, Dan [Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN (United States); Sandhu, Gurpreet S., E-mail: sandhu.gurpreet@mayo.edu [Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN (United States)

    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. - Highlights: • Magnetic stent-grafts were made from 2205 steel stents and polyurethane nanofibers. • Stent-grafts remained patent and formed a thin and uniform neointima when implanted. • Stent-grafts captured endothelial cells labeled with magnetic nanoparticles.

  13. MRT of carotid stents: influence of stent properties and sequence parameters on visualization of the carotid artery lumen

    International Nuclear Information System (INIS)

    Straube, T.; Wolf, S.; Alfke, K.; Jansen, O.; Flesser, A.; Deli, M.; Nabavi, A.

    2005-01-01

    Purpose: To evaluate MR artifacts of carotid artery stents and to optimize stent properties and sequence parameters. Material and Methods: Four carotid artery stents - Wallstent (mediloy), Precise (nitinol), ACCULINK (nitinol) and a stent prototype (nitinol) - were investigated in a flow model of the cervical vessels. The model was made of silicon tubing and a flow pump that produces realistic flow curves of the carotid artery. To investigate the effects of magnetic susceptibility and radiofrequency induced shielding artifacts, turbo spin echo and gradient echo sequences as well as CE-MRAs were measured. To improve the visualization of the stent lumen in a CE-MRA, flip angle as well as geometry and covering of the stent prototype were altered. Results: Susceptibility artifacts in stents of the carotid artery only influence the lumen visualization at the proximal and distal end of the braided mediloy stent. A change of stent coverings has no significant influence on radiofrequency artifacts, whereas a reduction in linking elements between stent segments and a change in diameter of stent struts improves visualization of the stent lumen. By increasing the flip angle in a CE-MRA, visualization of the stent lumen is possible in both mediloy and nitinol stents. Conclusion: The choice of stent material and changes in stent geometry as well as the optimization of the flip angle of the CE-MRA may reduce susceptibility and radiofrequency artifacts, rendering feasible the CE-MRA of a stented carotid artery. (orig.)

  14. Null-strut calculus. II. Dynamics

    International Nuclear Information System (INIS)

    Kheyfets, A.; LaFave, N.J.; Miller, W.A.

    1990-01-01

    In this paper, we continue from the preceding paper to develop a fully functional Regge calculus geometrodynamic algorithm from the null-strut-calculus construction. The developments discussed include (a) the identification of the Regge calculus analogue of the constraint and evolution equations on the null-strut lattice, (b) a description of the Minkowski solid geometry for the simplicial blocks of the null-strut lattice, (c) a description of the evolution algorithm for the geometrodynamic scheme and an analysis of its consistency, and (d) a presentation of the dynamical degrees of freedom for a simplicial hypersurface and the description of an initial-value prescription. To demonstrate qualitatively this new approach to geometrodynamics, we present the most simple application of null-strut calculus that we know of---the Friedmann cosmology using the three-boundary of a 600-cell simplicial polytope to model the simplicial hypersurface

  15. Drop Hammer Tests with Three Oleo Strut Models and Three Different Shock Strut Oils at Low Temperatures

    Science.gov (United States)

    Kranz, M

    1954-01-01

    Drop hammer tests with different shock strut models and shock strut oils were performed at temperatures ranging to -40 C. The various shock strut models do not differ essentially regarding their springing and damping properties at low temperatures; however, the influence of the different shock strut oils on the springing properties at low temperatures varies greatly.

  16. Optical coherence tomography findings after chronic total occlusion interventions: Insights from the “AngiographiC evaluation of the everolimus-eluting stent in chronic Total occlusions” (ACE-CTO) study (NCT01012869)

    Energy Technology Data Exchange (ETDEWEB)

    Sherbet, Daniel P.; Christopoulos, Georgios; Karatasakis, Aris; Danek, Barbara Anna; Kotsia, Anna; Navara, Rachita; Michael, Tesfaldet T.; Roesle, Michele; Rangan, Bavana V.; Haagen, Donald [VA North Texas Healthcare System and University of Texas Southwestern Medical Center, Dallas, TX (United States); Garcia, Santiago [Minneapolis VA Healthcare System and University of Minnesota, Minneapolis, MN (United States); Maniu, Calin [Bon Secours Health System, Suffolk, VA (United States); Pershad, Ashish [Banner Good Samaritan Medical Center, Phoenix, AZ (United States); Abdullah, Shuaib M.; Hastings, Jeffrey L.; Kumbhani, Dharam J.; Luna, Michael; Addo, Tayo; Banerjee, Subhash [VA North Texas Healthcare System and University of Texas Southwestern Medical Center, Dallas, TX (United States); Brilakis, Emmanouil S., E-mail: esbrilakis@gmail.com [VA North Texas Healthcare System and University of Texas Southwestern Medical Center, Dallas, TX (United States)

    2016-10-15

    Background: There is limited information on optical coherence tomography (OCT) findings after percutaneous coronary intervention (PCI) of chronic total occlusions (CTOs). OCT allows high resolution imaging that can enhance understanding of the vascular response after stenting of chronically occluded vessels. Methods: The Angiographic Evaluation of the Everolimus-Eluting Stent in Chronic Total Occlusions (ACE-CTO) study collected angiographic and clinical outcomes from 100 patients undergoing CTO PCI with the everolimus-eluting stent (EES). OCT was performed 8-months post stenting in 62 patients. Every third frame was analyzed throughout the course of the stented arterial segment. Lumen contours were semi-automatically traced and stent struts were manually delineated, with automatic measurement of the strut to lumen distance. Struts on the luminal side of the lumen contour were classified as malapposed if the distance to the lumen contour exceeded 0.108 mm. Results: A total of 44,450 struts in 6047 frames were analyzed, of which 4113 9.3%, 95% confidence intervals [CI] 9.0% to 9.5%) were malapposed and 1230 (2.8%, 95% CI 2.6% to 2.9%) were uncovered. Fifty-five of 62 patients (88.7%, 95% CI 78.5% to 98.4%) had at least one malapposed stent strut and 50 patients (80.7%, 95% CI 69.2% to 88.6%) had at least one uncovered stent strut. Mean strut-intimal thickness of the apposed and malapposed struts was 0.126 ± 0.140 mm and − 0.491 ± 0.440 mm, respectively. Conclusion: High rates of stent strut malapposition and incomplete stent strut coverage were observed after CTO PCI using EES, highlighting unique challenges associated with stent implantation in CTOs. - Highlights: • Percutaneous coronary intervention with drug-eluting stents for chronic total occlusion is associated with a 40% rate of binary in-stent restenosis at 8 months • Of patients who receive a drug eluting stent for a chronic total occlusion 88.7% will have stent strut malapposition and 80.7% will

  17. 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.

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

    Science.gov (United States)

    Lin, Jing; Guidoin, Robert; Du, Jia; Wang, Lu; Douglas, Graeham; Zhu, Danjie; Nutley, Mark; Perron, Lygia; Zhang, Ze; Douville, Yvan

    2016-02-16

    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.

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

    International Nuclear Information System (INIS)

    Lee, Da Un; Kim, Jae Kyu; Jung, Hye Doo; Huh, Tae Wook; Yim, Nam Yeol; Oh, Hyun jun; Choi, Soo Jin Na; Chang, Nam Kyu

    2010-01-01

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

  20. 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. Copyright © 2010 IPEM. Published by Elsevier Ltd. All rights reserved.

  1. 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.

  2. Null-strut calculus. I. Kinematics

    International Nuclear Information System (INIS)

    Kheyfets, A.; LaFave, N.J.; Miller, W.A.

    1990-01-01

    This paper describes the kinematics of null-strut calculus---a 3+1 Regge calculus approach to general relativity. We show how to model the geometry of spacetime with simplicial spacelike three-geometries (TET's) linked to ''earlier'' and ''later'' momentumlike lattice surfaces (TET * ) entirely by light rays or ''null struts.'' These three-layered lattice spacetime geometries are defined and analyzed using combinatorial formulas for the structure of polytopes. The following paper in this series describes how these three-layered spacetime lattices are used to model spacetimes in full conformity with Einstein's theory of gravity

  3. Variable volume combustor with aerodynamic support struts

    Science.gov (United States)

    Ostebee, Heath Michael; Johnson, Thomas Edward; Stewart, Jason Thurman; Keener, Christopher Paul

    2017-03-07

    The present application provides a combustor for use with a gas turbine engine. The combustor may include a number of micro-mixer fuel nozzles and a fuel injection system for providing a flow of fuel to the micro-mixer fuel nozzles. The fuel injection system may include a number of support struts supporting the fuel nozzles and providing the flow of fuel therethrough. The support struts may include an aerodynamic contoured shape so as to distribute evenly a flow of air to the micro-mixer fuel nozzles.

  4. Enhanced drug delivery capabilities from stents coated with absorbable polymer and crystalline drug

    OpenAIRE

    Carlyle, Wenda C.; McClain, James B.; Tzafriri, Abraham R.; Bailey, Lynn; Zani, Brett G.; Markham, Peter M.; Stanley, James R.L.; Edelman, Elazer R.

    2012-01-01

    Current drug eluting stent (DES) technology is not optimized with regard to the pharmacokinetics of drug delivery. A novel, absorbable-coating sirolimus-eluting stent (AC-SES) was evaluated for its capacity to deliver drug more evenly within the intimal area rather than concentrating drug around the stent struts and for its ability to match coating erosion with drug release. The coating consisted of absorbable poly-lactide-co-glycolic acid (PLGA) and crystalline sirolimus deposited by a dry-p...

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

    International Nuclear Information System (INIS)

    Maintz, David; Juergens, Kai-Uwe; Heindel, Walter; Fischbach, Roman; Wichter, Thomas; Grude, Matthias

    2003-01-01

    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.)

  6. Peri-stent aneurysm formation following a stent implant for stenotic intracranial vertebral artery dissection: a technical report of two cases successfully treated with coil embolization.

    Science.gov (United States)

    Ishimaru, Hideki; Nakashima, Kazuaki; Takahata, Hideaki; Matsuoka, Yohjiro

    2013-02-01

    Although stenting for stenotic vertebral artery dissection (VAD) improves compromised blood flow, subsequent peri-stent aneurysm (PSA) formation is not well-known. We report two cases with PSA successfully treated with coil embolization. Three patients with stenotic intracranial VAD underwent endovascular angioplasty at our institution because they had acute infarction in posterior circulation territory and clinical evidence of hemodynamic insufficiency. In two of three patients balloon angioplasty at first session failed to relieve the stenosis, and a coronary stent was implanted. Angiography immediately after stenting showed no abnormality in case 1 and minimal slit-like projection at proximal portion of the stent in case 2. Angiography obtained 16 months after the stenting revealed PSA in case 1. In case 2, angiography performed 3 months later showed that the projection at proximal portion enlarged and formed an aneurysm outside the stent. Because follow-up angiographies showed growth of the aneurysm in both cases, endovascular aneurysmal embolization was performed. We advanced a microcatheter into the aneurysm through the strut of existing stent and delivered detachable coils into the aneurysm lumen successfully in both cases. The post-procedural course was uneventful, and complete obliteration of aneurysm was confirmed on angiography in both cases. Stenting for stenotic intracranial VAD may result in delayed PSA; therefore, follow-up angiographies would be necessary after stenting for stenotic intracranial arterial dissection. Coil embolization through the stent strut would be a solution for enlarging PSA.

  7. Effects of 32P radioactive stents on in-stent restenosis in a double stent injury model of the porcine coronary arteries

    International Nuclear Information System (INIS)

    Kim, Han-Soo; Chan, Rosanna C.; Kollum, Marc; Au, Arthur; Tio, Fermin O.; Yazdi, Hamid A.; Ajani, Andrew E.; Waksman, Ron

    2001-01-01

    Background: The major limitation of coronary stenting remains in-stent restenosis, due to the development of neointimal proliferation. Radioactive stents have demonstrated the ability to reduce this proliferation in the healthy nonatherosclerotic porcine animal model. However, inhibition of tissue proliferation in the in-stent restenotic lesion in a porcine model is not well characterized. The objective of this study was to examine the efficacy and safety of the 32 P radioactive stent for the treatment of in-stent restenosis in a double stent injury model of the porcine coronaries. Methods and Materials: Eighteen coronary arteries in 9 pigs underwent nonradioactive stent (8 mm in length) implantation. Thirty days after the initial stent implantation, a 32 P radioactive stent (18 mm in length) with an activity of 0 and 18 μCi was implanted to cover the initial stent. The swine were killed 30 days after the second stent implantation. Histomorphometric analysis was performed for vessel area (VA), stent strut area (SSA), intimal area (IA), and lumen area (LA). Results: Injury scores, VA, SSA, and LA were similar among the control and radiated groups. Neointimal formation was significantly reduced after placement of radioactive stents as compared to control in both the overlapped (0.93±0.12 vs. 1.31±0.51 mm 2 , p 2 , p 32 P radioactive stents may be safe and effective in reducing neointimal formation leading to in-stent restenosis. Longer follow-up will be required to examine whether these positive findings can be maintained

  8. Stenting for curved lesions using a novel curved balloon: Preliminary experimental study.

    Science.gov (United States)

    Tomita, Hideshi; Higaki, Takashi; Kobayashi, Toshiki; Fujii, Takanari; Fujimoto, Kazuto

    2015-08-01

    Stenting may be a compelling approach to dilating curved lesions in congenital heart diseases. However, balloon-expandable stents, which are commonly used for congenital heart diseases, are usually deployed in a straight orientation. In this study, we evaluated the effect of stenting with a novel curved balloon considered to provide better conformability to the curved-angled lesion. In vitro experiments: A Palmaz Genesis(®) stent (Johnson & Johnson, Cordis Co, Bridgewater, NJ, USA) mounted on the Goku(®) curve (Tokai Medical Co. Nagoya, Japan) was dilated in vitro to observe directly the behavior of the stent and balloon assembly during expansion. Animal experiment: A short Express(®) Vascular SD (Boston Scientific Co, Marlborough, MA, USA) stent and a long Express(®) Vascular LD stent (Boston Scientific) mounted on the curved balloon were deployed in the curved vessel of a pig to observe the effect of stenting in vivo. In vitro experiments: Although the stent was dilated in a curved fashion, stent and balloon assembly also rotated conjointly during expansion of its curved portion. In the primary stenting of the short stent, the stent was dilated with rotation of the curved portion. The excised stent conformed to the curved vessel. As the long stent could not be negotiated across the mid-portion with the balloon in expansion when it started curving, the mid-portion of the stent failed to expand fully. Furthermore, the balloon, which became entangled with the stent strut, could not be retrieved even after complete deflation. This novel curved balloon catheter might be used for implantation of the short stent in a curved lesion; however, it should not be used for primary stenting of the long stent. Post-dilation to conform the stent to the angled vessel would be safer than primary stenting irrespective of stent length. Copyright © 2014 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  9. Time-dependent 3D simulations of the hemodynamics in a stented coronary artery

    International Nuclear Information System (INIS)

    Faik, Isam; Mongrain, Rosaire; Leask, Richard L; Rodes-Cabau, Josep; Larose, Eric; Bertrand, Olivier

    2007-01-01

    Stenting is becoming the major interventional cardiology procedure worldwide. However restenosis remains a major limitation to the effectiveness of stents. Alterations to the local hemodynamics in the stented segment of the artery could be a potential factor in the development of in-stent restenosis. The characterization of wall shear stress and of blood flow patterns in a stented artery is therefore necessary for a good understanding of the role of hemodynamics in the development of in-stent restenosis. We have used a time-dependent 3D numerical model of a stented coronary artery to study the characteristics of the blood flow and the shear stress distribution. Our results show that the presence of the stent produces significant secondary flow that is limited to an annulus in the near wall region. Low shear stress zones were localized in the vicinity of the struts while the tips of the struts exhibited high values of shear stress. These results support the hypothesis that local hemodynamics may affect the development of in-stent restenosis and could influence the choice of stent geometries for future stent designs

  10. Response of Balloon-Expandable Endoprosthetic Metallic Stents Subjected to Over-Expansion In Vitro

    International Nuclear Information System (INIS)

    Montague, B. J.; Kakimoto, W. M.; Arepally, A.; Razavi, M.; Dake, M. D.; Hofmann, L. V.

    2004-01-01

    We attempted to evaluate the in vitro behavior and performance of balloon-expandable endoprosthetic metallic stents subjected to over-expansion (OE). Seventy-two balloon-expandable endoprosthetic stents, representing 22 models from six manufacturers, were over- expanded in vitro. Stents were initially expanded to their maximum manufacturer- recommended diameter and then over-expanded incrementally to their endpoints. Endpoints for OE were either stent disarticulation or an inability to undergo further expansion despite balloon insufflation to maximum burst pressure. Measurements of stent dimensions were recorded at each overexpanded diameter and comparisons were made to manufacturer's specifications. A total of 288 balloon-driven expansions were performed on 72 stents. Sixteen stents were expanded to large diameters (≥ 16 mm), 20 stents underwent OE of 50% or greater. One model tended to disarticulate after OE greater than 50%. There were five models that had a tendency to disarticulate after minimal OE. Five models were resistant to OE (25% or less OE) but did not disarticulate. Nearly all stents showed some degree of foreshortening with OE, while 36 stents underwent foreshortening of 30% or more. Models that are not recommended for OE include Intrastent, Intrastent DoubleStrut, NIR Royale and Omniflex. Good candidates for OE include Intrastent DoubleStrut LD, Palmaz large, Medtronic Extra Support Biliary Plus and Medtronic Flexible Biliary. Palmaz XL remains the only model available for expansion from 20 to 28 mm in diameter. For the remaining stents, OE is possible, however, caution should be used

  11. Sensor to detect endothelialization on an active coronary stent

    Directory of Open Access Journals (Sweden)

    Coffey Arthur C

    2010-11-01

    Full Text Available Abstract Background A serious complication with drug-eluting coronary stents is late thrombosis, caused by exposed stent struts not covered by endothelial cells in the healing process. Real-time detection of this healing process could guide physicians for more individualized anti-platelet therapy. Here we present work towards developing a sensor to detect this healing process. Sensors on several stent struts could give information about the heterogeneity of healing across the stent. Methods A piezoelectric microcantilever was insulated with parylene and demonstrated as an endothelialization detector for incorporation within an active coronary stent. After initial characterization, endothelial cells were plated onto the cantilever surface. After they attached to the surface, they caused an increase in mass, and thus a decrease in the resonant frequencies of the cantilever. This shift was then detected electrically with an LCR meter. The self-sensing, self-actuating cantilever does not require an external, optical detection system, thus allowing for implanted applications. Results A cell density of 1300 cells/mm2 on the cantilever surface is detected. Conclusions We have developed a self-actuating, self-sensing device for detecting the presence of endothelial cells on a surface. The device is biocompatible and functions reliably in ionic liquids, making it appropriate for implantable applications. This sensor can be placed along the struts of a coronary stent to detect when the struts have been covered with a layer of endothelial cells and are no longer available surfaces for clot formation. Anti-platelet therapy can be adjusted in real-time with respect to a patient's level of healing and hemorrhaging risks.

  12. Refinement of a thrombectomy technique to treat acute ischemic stroke: Technical note on microcatheter advance during retrieving self expandable stent

    Energy Technology Data Exchange (ETDEWEB)

    Youn, Sung Won; Kim, Ho Kyun [Catholic Univ. of Daegu School of Medicine, Daegu (Korea, Republic of)

    2012-07-15

    Temporary stenting and thrombectomy by use of the Solitaire stent (ev3, Irvine, CA, USA) has shown prompt and successful recanalization of the acutely occluded major cerebral artery. However, even if rarely reported, inadvertent stent detachment may occur as an innate drawback and full deployment of the stent was considered to increase the risk. In our patients, the Solitaire stent did not fully unfold to prevent inadvertent detachment. Before retrieval of the stent, the tip of the microcatheter was advanced forward carefully under fluoroscopic observation until it met the presumed thrombus segment and a subtle sense of resistance was felt in the fingers guiding the stent. After retrieval, complete recanalization was achieved, and the thrombus was trapped between the tip of the microcatheter and the stent strut. We present 2 cases of successful thrombi captures by advancing a microcatheter during Solitaire stent retrieval, and we suggest that advancing the microcatheter can be a useful refinement to the thrombectomy technique for acute ischemic stroke.

  13. Mechanical properties of various z-stent designs: an endovascular stent-grafting perspective.

    Science.gov (United States)

    Bashar, Abul Hasan Muhammad; Kazui, Teruhisa; Washiyama, Naoki; Terada, Hitoshi; Yamashita, Katsushi; Haque, Mohammad E

    2003-08-01

    To comparatively assess the mechani-cal behavior of various clinically relevant Z-stent designs. A total of 16 Z-stents of original, biliary, spiral, and double-skirted designs (n=4 for each) were constructed using similar specifications for all. Stents were then evaluated for stiffness, snap opening force (SOF), flexibility, and displacement force using a novel tensiometer. Differences among the stents were determined using statistical methods. Stents explanted from dog aorta after a mean follow-up of 13 months were examined under a scanning electron microscope for surface defects. Forces required for about 50% reduction in diameter were 1.88 +/- 0.16 N, 3.81 +/- 0.21 N, 2.76 +/- 0.22 N, and 3.35 +/- 0.19 N for original, biliary, spiral, and skirted designs, respectively. Differences among the four designs were statistically significant at almost all points of measurement (P designs showed higher SOF values in the early measurements. Stents explanted from dog aorta after a mean duration of 13 months showed no obvious corrosion or breakage in the wire struts. Significant differences exist among the various Z-stent designs in terms of their mechanical properties. Understanding them should help to select the appropriate stent for a given lesion. 316L stainless steel shows a favorable long-term tissue interaction.

  14. An intriguing design concept to enhance the pulsatile fatigue life of self-expanding stents.

    Science.gov (United States)

    Hsiao, Hao-Ming; Yin, Ming-Ting

    2014-02-01

    Intravascular stenting has emerged as the primary treatment for vascular diseases and has received great attention from the medical community since its introduction two decades ago. The endovascular self-expanding stent is used to treat peripheral artery diseases; however, once implanted, these stents suffer from various cyclic motions caused by pulsatile blood pressure and daily activities. Due to this challenging environment, fatigue performance has become a critical issue for stent design. In this paper, a simple yet intriguing concept of stent design aimed at enhancing pulsatile fatigue life is investigated. The concept of this design is to shift the highly concentrated stresses/strains away from the crown and re-distribute them along the stress-free bar arm by tapering its strut width. Finite element models were developed to evaluate the mechanical integrity and pulsatile fatigue resistance of the stent to various loading conditions. Results show that the fatigue safety factor jumped to 2.5-3.0 times that of the standard stent with constant strut width. This is astonishing considering that the stent profile and scaffolding were not compromised. The findings of this paper provide an excellent approach to the optimization of future stent design to greatly improve stent fatigue performance.

  15. Computational design analysis for deployment of cardiovascular stents

    International Nuclear Information System (INIS)

    Tammareddi, Sriram; Sun Guangyong; Li Qing

    2010-01-01

    Cardiovascular disease has become a major global healthcare problem. As one of the relatively new medical devices, stents offer a minimally-invasive surgical strategy to improve the quality of life for numerous cardiovascular disease patients. One of the key associative issues has been to understand the effect of stent structures on its deployment behaviour. This paper aims to develop a computational model for exploring the biomechanical responses to the change in stent geometrical parameters, namely the strut thickness and cross-link width of the Palmaz-Schatz stent. Explicit 3D dynamic finite element analysis was carried out to explore the sensitivity of these geometrical parameters on deployment performance, such as dog-boning, fore-shortening, and stent deformation over the load cycle. It has been found that an increase in stent thickness causes a sizeable rise in the load required to deform the stent to its target diameter, whilst reducing maximum dog-boning in the stent. An increase in the cross-link width showed that no change in the load is required to deform the stent to its target diameter, and there is no apparent correlation with dog-boning but an increased fore-shortening with increasing cross-link width. The computational modelling and analysis presented herein proves an effective way to refine or optimise the design of stent structures.

  16. 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.

  17. Plastic strains during stent deployment have a critical influence on the rate of corrosion in absorbable magnesium stents.

    Science.gov (United States)

    Galvin, Emmet; Cummins, Christy; Yoshihara, Shoichiro; Mac Donald, Bryan J; Lally, Caitríona

    2017-08-01

    Magnesium stents are a promising candidate in the emerging field of absorbable metallic stents (AMSs). In this study, the mechanical and corrosion performance of dog-bone specimens and a specific stent design of a magnesium alloy, WE43, are assessed experimentally in terms of their corrosion behaviour and mechanical integrity. It is shown that plastic strains that are induced in the struts of the stent during stent deployment have a critical influence in directing subsequent corrosion behaviour within the material. In addition, the deployment and scaffolding characteristics of the magnesium stent are elucidated and contrasted with those of a commercial stainless steel stent. The magnesium stent is found to support higher levels of cyclic strain amplitude than the stainless steel stent, even prior to degradation, and this may play a role in reducing in-stent restenosis. This study provides new insights into the experimental performance of a current AMS design and material whilst demonstrating the critical influence of plastic strain on the corrosion performance and scaffolding ability of an AMS.

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

    NARCIS (Netherlands)

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

    2012-01-01

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

  19. Expandable stents.

    Science.gov (United States)

    Nesbitt, J C; Carrasco, H

    1996-05-01

    Expandable metallic stents are effective in selected patients with malignant or benign airway stenoses. When used for malignant lesions, the primary purpose of the stent is to improve the quality of life; stents are usually chosen for palliation of symptoms in recognition of the low likelihood of success for other therapy. For patients with benign stenoses, the stents provide a permanent source of structural support to alleviate the narrowed segment. The advantages of the expandable metallic stents are as follows: (1) they can be inserted through an endotracheal tube or under local anesthesia with relative simplicity under fluoroscopic guidance; (2) they do not impair the drainage of sputum because ciliary movement is not interrupted; (3) over a period of a few weeks, the meshwork is gradually covered with mucosa as the stent becomes incorporated into the airway wall; (4) ventilation usually is not impaired if the metallic mesh stent covers another nonstenosed bronchus, because the interstices of the stent are nonobstructive; and (5) they are dynamic and continue to expand over time, particularly if concurrent treatment achieves an effect on the lesion that caused stenosis. Disadvantages of the expandable stent include (1) they often are only temporarily effective for tracheobronchial stenosis due to intraluminal tumor or granulation tissue, both of which can grow between the wires; (2) they are considered permanent stents because removal is difficult; and (3) they can be poorly positioned during placement or can become displaced by progressive migration after placement, and they cannot be repositioned. A relative contraindication to insertion is an inflammatory process or infection that can predispose to granulation formation, particularly at the points of maximal contact pressure of the stent to the airway mucosa. In the presence of inflammation, it may be better to use a silicone prosthesis until the inflammatory process subsides and fibrosis occurs. Granulation

  20. Measurement of in vitro and in vivo stent geometry and deformation by means of 3D imaging and stereo-photogrammetry.

    Science.gov (United States)

    Zwierzak, Iwona; Cosentino, Daria; Narracott, Andrew J; Bonhoeffer, Philipp; Diaz, Vanessa; Fenner, John W; Schievano, Silvia

    2014-12-01

    To quantify variability of in vitro and in vivo measurement of 3D device geometry using 3D and biplanar imaging. Comparison of stent reconstruction is reported for in vitro coronary stent deployment (using micro-CT and optical stereo-photogrammetry) and in vivo pulmonary valve stent deformation (using 4DCT and biplanar fluoroscopy). Coronary stent strut length and inter-strut angle were compared in the fully deployed configuration. Local (inter-strut angle) and global (dog-boning ratio) measures of stent deformation were reported during stent deployment. Pulmonary valve stent geometry was assessed throughout the cardiac cycle by reconstruction of stent geometry and measurement of stent diameter. Good agreement was obtained between methods for assessment of coronary stent geometry with maximum disagreement of +/- 0.03 mm (length) and +/- 3 degrees (angle). The stent underwent large, non-uniform, local deformations during balloon inflation, which did not always correlate with changes in stent diameter. Three-dimensional reconstruction of the pulmonary valve stent was feasible for all frames of the fluoroscopy and for 4DCT images, with good correlation between the diameters calculated from the two methods. The largest compression of the stent during the cardiac cycle was 6.98% measured from fluoroscopy and 7.92% from 4DCT, both in the most distal ring. Quantitative assessment of stent geometry reconstructed from biplanar imaging methods in vitro and in vivo has shown good agreement with geometry reconstructed from 3D techniques. As a result of their short image acquisition time, biplanar methods may have significant advantages in the measurement of dynamic 3D stent deformation.

  1. Metallic Limus-Eluting Stents Abluminally Coated with Biodegradable Polymers: Angiographic and Clinical Comparison of a Novel Ultra-Thin Sirolimus Stent Versus Biolimus Stent in the DESTINY Randomized Trial.

    Science.gov (United States)

    Lemos, Pedro A; Abizaid, Alexandre A C; Meireles, George C; Sarmento-Leite, Rogério; Prudente, Mauricio; Cantarelli, Marcelo; Dourado, Adriano D; Mariani, Jose; Perin, Marco A; Costantini, Costantino; Costa, Ricardo A; Costa, José Ribamar; Chamie, Daniel; Campos, Carlos A; Ribeiro, Expedito

    2015-12-01

    To evaluate the outcomes of patients treated with a new drug-eluting stent formulation with low doses of sirolimus, built in an ultra-thin-strut platform coated with biodegradable abluminal coating. This study is a randomized trial that tested the main hypothesis that the angiographic late lumen loss of the novel sirolimus-eluting stent is noninferior compared with commercially available biolimus-eluting stent. A final study population comprising 170 patients with one or two de novo lesions was randomized in the ratio 2:1 for sirolimus-eluting stent or biolimus-eluting stent, respectively. The primary endpoint was 9-month angiographic in-stent late lumen loss. Adverse clinical events were prospectively collected for 1 year. After 9 months, the novel sirolimus-eluting stent was shown noninferior compared with the biolimus stent for the primary endpoint (angiographic in-stent late lumen loss: 0.20 ± 0.29 mm vs. 0.15 ± 0.20 mm, respectively; P value for noninferiority <0.001). The 1-year incidence of death, myocardial infarction, repeat revascularization, and stent thrombosis remained low and not significantly different between the groups. The present randomized trial demonstrates that the tested novel sirolimus-eluting stent was angiographically noninferior in comparison with a last-generation biolimus-eluting stent. © 2015 John Wiley & Sons Ltd.

  2. Hemodynamics in stented vertebral artery ostial stenosis based on computational fluid dynamics simulations.

    Science.gov (United States)

    Qiao, Aike; Dai, Xuan; Niu, Jing; Jiao, Liqun

    2016-01-01

    Hemodynamic factors may affect the potential occurrence of in-stent restenosis (ISR) after intervention procedure of vertebral artery ostial stenosis (VAOS). The purpose of the present study is to investigate the influence of stent protrusion length in implantation strategy on the local hemodynamics of the VAOS. CTA images of a 58-year-old female patient with posterior circulation transient ischemic attack were used to perform a 3D reconstruction of the vertebral artery. Five models of the vertebral artery before and after the stent implantation were established. Model 1 was without stent implantation, Model 2-5 was with stent protruding into the subclavian artery for 0, 1, 2, 3 mm, respectively. Computational fluid dynamics simulations based on finite element analysis were employed to mimic the blood flow in arteries and to assess hemodynamic conditions, particularly the blood flow velocity and wall shear stress (WSS). The WSS and the blood flow velocity at the vertebral artery ostium were reduced by 85.33 and 35.36% respectively after stents implantation. The phenomenon of helical flow disappeared. Hemodynamics comparison showed that stent struts that protruded 1 mm into the subclavian artery induced the least decrease in blood speed and WSS. The results suggest that stent implantation can improve the hemodynamics of VAOS, while stent struts that had protruded 1 mm into the subclavian artery would result in less thrombogenesis and neointimal hyperplasia and most likely decrease the risk of ISR.

  3. Changes in the mechanical environment of stenotic arteries during interaction with stents: computational assessment of parametric stent designs.

    Science.gov (United States)

    Holzapfel, Gerhard A; Stadler, Michael; Gasser, Thomas C

    2005-02-01

    Clinical studies have identified factors such as the stent design and the deployment technique that are one cause for the success or failure of angioplasty treatments. In addition, the success rate may also depend on the stenosis type. Hence, for a particular stenotic artery, the optimal intervention can only be identified by studying the influence of factors such as stent type, strut thickness, geometry of the stent cell, and stent-artery radial mismatch with the wall. We propose a methodology that allows a set of stent parameters to be varied, with the aim of evaluating the difference in the mechanical environment within the wall before and after angioplasty with stenting. Novel scalar quantities attempt to characterize the wall changes inform of the contact pressure caused by the stent struts, and the stresses within the individual components of the wall caused by the stent. These quantities are derived numerically and serve as indicators, which allow the determination of the correct size and type of the stent for each individual stenosis. In addition, the luminal change due to angioplasty may be computed as well. The methodology is demonstrated by using a full three-dimensional geometrical model of a postmortem specimen of a human iliac artery with a stenosis using imaging data. To describe the material behavior of the artery, we considered mechanical data of eight different vascular tissues, which formed the stenosis. The constitutive models for the tissue components capture the typical anisotropic, nonlinear and dissipative characteristics under supra-physiological loading conditions. Three-dimensional stent models were parametrized in such a way as to enable new designs to be generated simply with regard to variations in their geometric structure. For the three-dimensional stent-artery interaction we use a contact algorithm based on smooth contact surfaces of at least C-continuity, which prevents numerical problems known from standard facet-based contact

  4. Airway stents

    Science.gov (United States)

    Keyes, Colleen

    2018-01-01

    Stents and tubes to maintain the patency of the airways are commonly used for malignant obstruction and are occasionally employed in benign disease. Malignant airway obstruction usually results from direct involvement of bronchogenic carcinoma, or by extension of carcinomas occurring in the esophagus or the thyroid. External compression from lymph nodes or metastatic disease from other organs can also cause central airway obstruction. Most malignant airway lesions are surgically inoperable due to advanced disease stage and require multimodality palliation, including stent placement. As with any other medical device, stents have significantly evolved over the last 50 years and deserve an in-depth understanding of their true capabilities and complications. Not every silicone stent is created equal and the same holds for metallic stents. Herein, we present an overview of the topic as well as some of the more practical and controversial issues surrounding airway stents. We also try to dispel the myths surrounding stent removal and their supposed use only in central airways. At the end, we come to the long-held conclusion that stents should not be used as first line treatment of choice, but after ruling out the possibility of curative surgical resection or repair. PMID:29707506

  5. Coronary Stents: The Impact of Technological Advances on Clinical Outcomes.

    Science.gov (United States)

    Mennuni, Marco G; Pagnotta, Paolo A; Stefanini, Giulio G

    2016-02-01

    Percutaneous coronary interventions (PCI) were proposed in the late 1970s as an alternative to surgical coronary artery bypass grafting for the treatment of coronary artery disease. Important technological progress has been made since. Balloon angioplasty was replaced by bare metal stents, which allowed to permanently scaffold the coronary vessel avoiding acute recoil and abrupt occlusion. Thereafter, the introduction of early generation drug-eluting stents (DES) has significantly improved clinical outcomes, primarily by markedly reducing the risk of restenosis. New generation DES with thinner stent struts, novel durable or biodegradable polymer coatings, and new limus antiproliferative agents, have further improved upon the safety and efficacy profile of early generation DES. The present article aims to review the impact of technological advances on clinical outcomes in the field of PCI with coronary stents, and to provide a brief overview on clinical margins of improvement and unmet needs of available DES.

  6. Stent coverage and neointimal proliferation in bare metal stents postdilated with a Paclitaxel-eluting balloon versus everolimus-eluting stents: prospective randomized study using optical coherence tomography at 6-month follow-up.

    Science.gov (United States)

    Poerner, Tudor C; Otto, Sylvia; Gassdorf, Johannes; Nitsche, Kristina; Janiak, Florian; Scheller, Bruno; Goebel, Björn; Jung, Christian; Figulla, Hans R

    2014-12-01

    In this randomized trial, strut coverage and neointimal proliferation of a therapy of bare metal stents (BMSs) postdilated with the paclitaxel drug-eluting balloon (DEB) was compared with everolimus drug-eluting stents (DESs) at 6-month follow-up using optical coherence tomography. We hypothesized sufficient stent coverage at follow-up. A total of 105 lesions in 90 patients were treated with either XIENCE V DES (n=51) or BMS postdilated with the SeQuent Please DEB (n=54). At follow-up, comparable results on the primary optical coherence tomography end point (percentage uncovered struts 5.64±9.65% in BMS+DEB versus 4.93±9.29% in DES; P=0.366) were found. Thus, BMS+DEB achieved the prespecified noninferiority margin of 5% uncovered struts versus DES (difference between treatment means, 0.71%; one-sided upper 95% confidence interval, 4.14%; noninferiority P=0.04). Optical coherence tomography analysis showed significantly more global neointimal proliferation in the BMS+DEB group (15.7±7.8 versus 11.0±5.2 mm(3) proliferation volume/cm stent length; P=0.002). No significant focal in-stent stenosis analyzed with angiography (percentage diameter stenosis at follow-up, 22.8±11.9 versus 16.9±10.4; P=0.014) and optical coherence tomography (peak local area stenosis, 39.5±13.8% versus 36.8±15.6%; P=0.409) was found. Good stent strut coverage of >94% was found in both therapy groups. Despite greater suppression of global neointimal growth in DES, both DES and BMS+DEB effectively prevented clinically relevant focal restenosis at 6-month follow-up. http://www.clinicaltrials.gov. Unique identifier: NCT01056744. © 2014 American Heart Association, Inc.

  7. Automated peroperative assessment of stents apposition from OCT pullbacks.

    Science.gov (United States)

    Dubuisson, Florian; Péry, Emilie; Ouchchane, Lemlih; Combaret, Nicolas; Kauffmann, Claude; Souteyrand, Géraud; Motreff, Pascal; Sarry, Laurent

    2015-04-01

    This study's aim was to control the stents apposition by automatically analyzing endovascular optical coherence tomography (OCT) sequences. Lumen is detected using threshold, morphological and gradient operators to run a Dijkstra algorithm. Wrong detection tagged by the user and caused by bifurcation, struts'presence, thrombotic lesions or dissections can be corrected using a morphing algorithm. Struts are also segmented by computing symmetrical and morphological operators. Euclidian distance between detected struts and wall artery initializes a stent's complete distance map and missing data are interpolated with thin-plate spline functions. Rejection of detected outliers, regularization of parameters by generalized cross-validation and using the one-side cyclic property of the map also optimize accuracy. Several indices computed from the map provide quantitative values of malapposition. Algorithm was run on four in-vivo OCT sequences including different incomplete stent apposition's cases. Comparison with manual expert measurements validates the segmentation׳s accuracy and shows an almost perfect concordance of automated results. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Dynamic testing of airplane shock-absorbing struts

    Science.gov (United States)

    Langer, P; Thome, W

    1932-01-01

    Measurement of perpendicular impacts of a landing gear with different shock-absorbing struts against the drum testing stand. Tests were made with pneumatic shock absorbers having various degrees of damping, liquid shock absorbers, steel-spring shock absorbers and rigid struts. Falling tests and rolling tests. Maximum impact and gradual reduction of the impacts in number and time in the falling tests. Maximum impact and number of weaker impacts in rolling tests.

  9. In-situ investigation of stress conditions during expansion of bare metal stents and PLLA-coated stents using the XRD sin(2)ψ-technique.

    Science.gov (United States)

    Kowalski, Wolfgang; Dammer, Markus; Bakczewitz, Frank; Schmitz, Klaus-Peter; Grabow, Niels; Kessler, Olaf

    2015-09-01

    Drug eluting stents (DES) consist of platform, coating and drug. The platform often is a balloon-expandable bare metal stent made of the CoCr alloy L-605 or stainless steel 316 L. The function of the coating, typically a permanent polymer, is to hold and release the drug, which should improve therapeutic outcome. Before implantation, DES are compressed (crimped) to allow implantation in the human body. During implantation, DES are expanded by balloon inflation. Crimping, as well as expansion, causes high stresses and high strains locally in the DES struts, as well as in the polymer coating. These stresses and strains are important design criteria of DES. Usually, they are calculated numerically by finite element analysis (FEA), but experimental results for validation are hardly available. In this work, the X-ray diffraction (XRD) sin(2)ψ-technique is applied to in-situ determination of stress conditions of bare metal L-605 stents, and Poly-(L-lactide) (PLLA) coated stents. This provides a realistic characterization of the near-surface stress state and a validation option of the numerical FEA. XRD-results from terminal stent struts of the bare metal stent show an increasing compressive load stress in tangential direction with increasing stent expansion. These findings correlate with numerical FEA results. The PLLA-coating also bears increasing compressive load stress during expansion. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    Douglas, Gillian; Van Kampen, Erik; Hale, Ashley B; McNeill, Eileen; Patel, Jyoti; Crabtree, Mark J; Ali, Ziad; Hoerr, Robert A; Alp, Nicholas J; Channon, Keith M

    2013-11-01

    Understanding endothelial cell repopulation post-stenting and how this modulates in-stent restenosis is critical to improving arterial healing post-stenting. We used a novel murine stent model to investigate endothelial cell repopulation post-stenting, comparing the response of drug-eluting stents with a primary genetic modification to improve endothelial cell function. Endothelial cell repopulation was assessed en face in stented arteries in ApoE(-/-) mice with endothelial-specific LacZ expression. Stent deployment resulted in near-complete denudation of endothelium, but was followed by endothelial cell repopulation, by cells originating from both bone marrow-derived endothelial progenitor cells and from the adjacent vasculature. Paclitaxel-eluting stents reduced neointima formation (0.423 ± 0.065 vs. 0.240 ± 0.040 mm(2), P = 0.038), but decreased endothelial cell repopulation (238 ± 17 vs. 154 ± 22 nuclei/mm(2), P = 0.018), despite complete strut coverage. To test the effects of selectively improving endothelial cell function, we used transgenic mice with endothelial-specific overexpression of GTP-cyclohydrolase 1 (GCH-Tg) as a model of enhanced endothelial cell function and increased NO production. GCH-Tg ApoE(-/-) mice had less neointima formation compared with ApoE(-/-) littermates (0.52 ± 0.08 vs. 0.26 ± 0.09 mm(2), P = 0.039). In contrast to paclitaxel-eluting stents, reduced neointima formation in GCH-Tg mice was accompanied by increased endothelial cell coverage (156 ± 17 vs. 209 ± 23 nuclei/mm(2), P = 0.043). Drug-eluting stents reduce not only neointima formation but also endothelial cell repopulation, independent of strut coverage. In contrast, selective targeting of endothelial cell function is sufficient to improve endothelial cell repopulation and reduce neointima formation. Targeting endothelial cell function is a rational therapeutic strategy to improve vascular healing and decrease neointima formation after stenting.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Cheng-Hung [Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou, Chang Gung University College of Medicine, Tao-Yuan, Taiwan (China); Department of Mechanical Engineering, Chang Gung University, Tao-Yuan, Taiwan (China); Jhong, Guan-Heng [Graduate Institute of Medical Mechatronics, Chang Gung University, Tao-Yuan, Taiwan (China); Hsu, Ming-Yi; Wang, Chao-Jan [Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital, Linkou, Tao-Yuan, Taiwan (China); Liu, Shih-Jung, E-mail: shihjung@mail.cgu.edu.tw [Department of Mechanical Engineering, Chang Gung University, Tao-Yuan, Taiwan (China); Hung, Kuo-Chun [Division of Cardiology, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou, Chang Gung University College of Medicine, Tao-Yuan, Taiwan (China)

    2014-05-28

    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 < 0.01). The maximal stress on the vessels was significantly higher at bifurcation angle <70° than at angle ≧70° (P < 0.05). The maximal stress on the vessels was negatively correlated with bifurcation angle (P < 0.01). Stresses at the bifurcation ostium may cause arterial wall injury and restenosis, especially at small bifurcation angles. These finding highlight the effect of force-induced mechanical stress at coronary artery bifurcation stenting, and potential mechanisms of in-stent restenosis, along with their relationship with bifurcation angle.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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 < 0.01). The maximal stress on the vessels was significantly higher at bifurcation angle <70° than at angle ≧70° (P < 0.05). The maximal stress on the vessels was negatively correlated with bifurcation angle (P < 0.01). Stresses at the bifurcation ostium may cause arterial wall injury and restenosis, especially at small bifurcation angles. These finding highlight the effect of force-induced mechanical stress at coronary artery bifurcation stenting, and potential mechanisms of in-stent restenosis, along with their relationship with bifurcation angle.

  13. Efficacy and safety of catheter-based radiofrequency renal denervation in stented renal arteries.

    Science.gov (United States)

    Mahfoud, Felix; Tunev, Stefan; Ruwart, Jennifer; Schulz-Jander, Daniel; Cremers, Bodo; Linz, Dominik; Zeller, Thomas; Bhatt, Deepak L; Rocha-Singh, Krishna; Böhm, Michael; Melder, Robert J

    2014-12-01

    In selected patients with hypertension, renal artery (RA) stenting is used to treat significant atherosclerotic stenoses. However, blood pressure often remains uncontrolled after the procedure. Although catheter-based renal denervation (RDN) can reduce blood pressure in certain patients with resistant hypertension, there are no data on the feasibility and safety of RDN in stented RA. We report marked blood pressure reduction after RDN in a patient with resistant hypertension who underwent previous stenting. Subsequently, radiofrequency ablation was investigated within the stented segment of porcine RA, distal to the stented segment, and in nonstented RA and compared with stent only and untreated controls. There were neither observations of thrombus nor gross or histological changes in the kidneys. After radiofrequency ablation of the nonstented RA, sympathetic nerves innervating the kidney were significantly reduced, as indicated by significant decreases in sympathetic terminal axons and reduction of norepinephrine in renal tissue. Similar denervation efficacy was found when RDN was performed distal to a renal stent. In contrast, when radiofrequency ablation was performed within the stented segment of the RA, significant sympathetic nerve ablation was not seen. Histological observation showed favorable healing in all arteries. Radiofrequency ablation of previously stented RA demonstrated that RDN provides equally safe experimental procedural outcomes in a porcine model whether the radiofrequency treatment is delivered within, adjacent, or without the stent struts being present in the RA. However, efficacious RDN is only achieved when radiofrequency ablation is delivered to the nonstented RA segment distal to the stent. © 2014 American Heart Association, Inc.

  14. Stent placement of gastroenteric anastomoses formed by magnetic compression.

    Science.gov (United States)

    Cope, C; Clark, T W; Ginsberg, G; Habecker, P

    1999-01-01

    To evaluate the use of stents for prolonging the patency of gastroenteric anastomoses (GEA) induced by magnet compression. Rare earth magnets were inserted perorally and serially in 15 dogs so as to mate across the gastric and jejunal walls. After magnet excretion, the resulting GEA was identified endoscopically, dilated (n = 1), and stented with bare (n = 2) or partially covered (n = 6) flared 10-mm or 12-mm Z stents. The GEA was followed at 2-4-week intervals for patency; malfunctioning shunts were irrigated, or dilated with angioplasty balloons. Gross and histologic examination of the anastomotic tissues was performed in 14 animals. Magnet pairs were excreted in 5-7 days. Of the 19 magnet placements in 15 animals, stent placement was not possible because of early GEA closure (n = 6), failure to locate (n = 2), pancreatic abscess (n = 1), and magnet perforation with peritonitis (n = 1). Estimated duration of GEA patency was 19 days after balloon dilation, 40-64 days with bare Z stents, and 58-147 days (mean, 90 days) with partially covered Z stents. Shunt function was commonly hindered by bezoars. Stent narrowing or occlusion was caused by tissue overgrowth through bare stents (n = 2), between covered stent struts and through partially detached membrane (n = 2). Serious morbidity (n = 2) was due to malpositioned magnets across the pancreas in one animal and gastric perforation in the other. One dog was euthanized because of unsuspected kidney infection. Partially covered stents significantly extend the anatomic patency rate of magnetic GEA to 7 weeks or more. Functional patency is frequently impaired by bezoars. Ongoing improvements in covered stent design should provide longer-term GEA patency.

  15. A new method of thermal protection by opposing jet for a hypersonic aeroheating strut

    Science.gov (United States)

    Qin, Jiang; Ning, Dongpo; Feng, Yu; Zhang, Junlong; Feng, Shuo; Bao, Wen

    2017-06-01

    This paper presents the numerical investigation of thermal protection of scramjet strut by opposing jet in supersonic stream of Mach number 6 with a hydrogen fueled scramjet strut model using CFD software. Simulation results indicate that when a small amount of fuel is injected from the nose of the strut, the bow shock is pushed away from the strut, and the heat flux is reduced in the strut, especially at the leading edge. Opposing jet forms a recirculation region near the nozzle so that the strut is covered with low temperature fuel and separated from free stream. An appropriate total pressure ratio can be used to reduce not only aerodynamic heating but also the drag of strut. It is therefore concluded that thermal protection of scramjet strut by opposing jet is one of the promising ways to protect scramjet strut in high enthalpy stream.

  16. Use of flow-diverting stents as salvage treatment following failed stent-assisted embolization of intracranial aneurysms.

    Science.gov (United States)

    Heiferman, Daniel M; Billingsley, Joshua T; Kasliwal, Manish K; Johnson, Andrew K; Keigher, Kiffon M; Frudit, Michel E; Moftakhar, Roham; Lopes, Demetrius K

    2016-07-01

    Flow-diverting stents, including the Pipeline embolization device (PED) and Silk, have been beneficial in the treatment of aneurysms previously unable to be approached via endovascular techniques. Recurrent aneurysms for which stent-assisted embolization has failed are a therapeutic challenge, given the existing intraluminal construct with continued blood flow into the aneurysm. We report our experience using flow-diverting stents in the repair of 25 aneurysms for which stent-assisted embolization had failed. Nineteen (76%) of these aneurysms at the 12-month follow-up showed improved Raymond class occlusion, with 38% being completely occluded, and all aneurysms demonstrated decreased filling. One patient developed a moderate permanent neurologic deficit. Appropriate stent sizing, proximal and distal construct coverage, and preventing flow diverter deployment between the previously deployed stent struts are important considerations to ensure wall apposition and prevention of endoleak. Flow diverters are shown to be a reasonable option for treating previously stented recurrent cerebral aneurysms. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  17. Bioabsorbable Stent Quo Vadis: A Case for Nano-Theranostics

    Science.gov (United States)

    Gundogan, Buket; Tan, Aaron; Farhatnia, Yasmin; Alavijeh, Mohammad S.; Cui, Zhanfeng; Seifalian, Alexander M.

    2014-01-01

    Percutaneous coronary intervention (PCI) is one of the most commonly performed invasive medical procedures in medicine today. Since the first coronary balloon angioplasty in 1977, interventional cardiology has seen a wide array of developments in PCI. Bare metal stents (BMS) were soon superseded by the revolutionary drug-eluting stents (DES), which aimed to address the issue of restenosis found with BMS. However, evidence began to mount against DES, with late-stent thrombosis (ST) rates being higher than that of BMS. The bioabsorbable stent may be a promising alternative, providing vessel patency and support for the necessary time required and thereafter degrade into safe non-toxic compounds which are reabsorbed by the body. This temporary presence provides no triggers for ST, which is brought about by non-endothelialized stent struts and drug polymers remaining in vivo for extended periods of time. Likewise, nano-theranostics incorporated into a bioabsorbable stent of the future may provide an incredibly valuable single platform offering both therapeutic and diagnostic capabilities. Such a stent may allow delivery of therapeutic particles to specific sites thus keeping potential toxicity to a minimum, improved ease of tracking delivery in vivo by embedding imaging agents, controlled rate of therapy release and protection of the implanted therapy. Indeed, nanocarriers may allow an increased therapeutic index as well as offer novel post-stent implantation imaging and diagnostic methods for atherosclerosis, restenosis and thrombosis. It is envisioned that a nano-theranostic stent may well form the cornerstone of future stent designs in clinical practice. PMID:24672583

  18. Irradiated strut allografts for reconstructing tumour defects: how effective?

    International Nuclear Information System (INIS)

    Astrid Lobo Gajiwala; Manish Agarwal; Ajay Puri; Cynthia D Lima

    2008-01-01

    Full text: Allografts are biological options for reconstructing large bone defects. We report our experience with 87 irradiated (25 kGy of gamma radiation) strut allografts used in various defects following tumour surgery. Reconstruction in 35 full segment defects involved 22 full segment allografts used alone, 4 allograft prosthetic composites (APC) and 9 allografts combined with a vascularized fibula. Twelve partial segment defects were reconstructed with allograft struts (including 2 APC). Full segment allograft struts (mainly fibulae) were used in 40 contained post-curettage defects. The cases were studied for time to incorporation and complications. The follow-up ranged from 12 to 72 months. Of the 26 full segment defects where allograft alone or APC was used, 2 were lost to follow-up, 5 died before incorporation and 3 grafts were removed (2 infection and 1 local recurrence). Six united primarily at 2-4 years. Seven patients with non union were autografted at both junctions resulting in 6 unions. One patient had early plate breakage and refused further treatment. One allograft fractured after union after autografting. Two of 4 APC also united. In contrast, the 9 allograft-vascularized fibula combinations showed unambiguous incorporation between 5-9 months with only one junction requiring bone grafting. Of the 12 partial segment struts, barring one removed for infection, 11 have completely incorporated. Thirty one out of 40 struts placed within contained post curettage defects have incorporated (2 removed for infection and seven lost to follow-up). There were total 6 infections (7%) 4 of which occurred 1-2 years after surgery. Irradiated full segment struts alone incorporate poorly and are best used combined with a live fibula. Irradiated full and partial segment allografts used inside contained defects give consistently good results. Frozen grafts seem to incorporate faster and better than lyophilised grafts. (Author)

  19. Advantages of novel BioMimeTM Sirolimus Eluting Coronary Stent system. Moving towards biomimicry.

    Science.gov (United States)

    Upendra, K; Sanjeev, B

    2012-02-01

    Since the first reported use of percutaneous transluminal coronary angioplasty (PTCA), advancements in interventional cardiology arena have been fast paced. Within the last ten years, these developments have been exponential. Developers & clinicians are fast adapting from the learning curve awarded by the time course of DES evolution. In that light BioMimeTM Sirolimus Eluting Coronary Stent comes as a fresh thought in taking stents towards a biomimicry concept. The stent is built on an ultra-low strut thickness (65 µm) cobalt chromium stent platform, using an intelligent hybrid of close and open cells allowing for morphology mediated expansion, employs a well known anti-proliferative - Sirolimus that elutes from a biodegradable co-polymer formulation in 30 days and ensures high coating integrity and low coating thickness of 2 µm. The resultant stent demonstrates almost 100% endothelialization at 30 days in preclinical model and zero percent MACE >18 months in the primary efficacy and safety clinical study.

  20. Strut fracture in a Bjork-Shiley aortic valve prosthesis.

    Science.gov (United States)

    Lifschultz, B D; Donoghue, E R

    1985-10-01

    Strut fracture can be a life-threatening adverse effect of mechanical prosthetic heart valves. This complication has occurred in the DeBakey, the Beall, the Cooley-Cutter and, most recently, the Bjork-Shiley valves. We report the case of a 35-year-old man who died suddenly 16 months after a 60 degree Bjork-Shiley Convexo-Concave heart valve prosthesis was inserted in the aortic position. At autopsy, the two welded attachments of the valve's outlet strut had fractured. The valve's tilting disc was found in his abdominal aorta.

  1. Design and Manufacture of Structurally Efficient Tapered Struts

    Science.gov (United States)

    Brewster, Jebediah W.

    2009-01-01

    Composite materials offer the potential of weight savings for numerous spacecraft and aircraft applications. A composite strut is just one integral part of the node-to-node system and the optimization of the shut and node assembly is needed to take full advantage of the benefit of composites materials. Lockheed Martin designed and manufactured a very light weight one piece composite tapered strut that is fully representative of a full scale flight article. In addition, the team designed and built a prototype of the node and end fitting system that will effectively integrate and work with the full scale flight articles.

  2. Development of tissue-engineered self-expandable aortic stent grafts (Bio stent grafts) using in-body tissue architecture technology in beagles.

    Science.gov (United States)

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

    2015-02-01

    In this study, we aimed to describe the development of tissue-engineered self-expandable aortic stent grafts (Bio stent graft) using in-body tissue architecture technology in beagles and to determine its mechanical and histological properties. The preparation mold was assembled by insertion of an acryl rod (outer diameter, 8.6 mm; length, 40 mm) into a self-expanding nitinol stent (internal diameter, 9.0 mm; length, 35 mm). The molds (n = 6) were embedded into the subcutaneous pouches of three beagles for 4 weeks. After harvesting and removing each rod, the excessive fragile tissue connected around the molds was trimmed, and thus tubular autologous connective tissues with the stent were obtained for use as Bio stent grafts (outer diameter, approximately 9.3 mm in all molds). The stent strut was completely surrounded by the dense collagenous membrane (thickness, ∼150 µm). The Bio stent graft luminal surface was extremely flat and smooth. The graft wall of the Bio stent graft possessed an elastic modulus that was almost two times higher than that of the native beagle abdominal aorta. This Bio stent graft is expected to exhibit excellent biocompatibility after being implanted in the aorta, which may reduce the risk of type 1 endoleaks or migration. © 2014 Wiley Periodicals, Inc.

  3. Enhanced drug delivery capabilities from stents coated with absorbable polymer and crystalline drug.

    Science.gov (United States)

    Carlyle, Wenda C; McClain, James B; Tzafriri, Abraham R; Bailey, Lynn; Zani, Brett G; Markham, Peter M; Stanley, James R L; Edelman, Elazer R

    2012-09-28

    Current drug eluting stent (DES) technology is not optimized with regard to the pharmacokinetics of drug delivery. A novel, absorbable-coating sirolimus-eluting stent (AC-SES) was evaluated for its capacity to deliver drug more evenly within the intimal area rather than concentrating drug around the stent struts and for its ability to match coating erosion with drug release. The coating consisted of absorbable poly-lactide-co-glycolic acid (PLGA) and crystalline sirolimus deposited by a dry-powder electrostatic process. The AC-SES demonstrated enhanced drug stability under simulated use conditions and consistent drug delivery balanced with coating erosion in a porcine coronary implant model. The initial drug burst was eliminated and drug release was sustained after implantation. The coating was absorbed within 90 days. Following implantation into porcine coronary arteries the AC-SES coating is distributed in the surrounding intimal tissue over the course of several weeks. Computational modeling of drug delivery characteristics demonstrates how distributed coating optimizes the load of drug immediately around each stent strut and extends drug delivery between stent struts. The result was a highly efficient arterial uptake of drug with superior performance to a clinical bare metal stent (BMS). Neointimal thickness (0.17±0.07 mm vs. 0.28±0.11 mm) and area percent stenosis (22±9% vs. 35±12%) were significantly reduced (pstent implantation in an overlap configuration in porcine coronary arteries. Inflammation was significantly reduced in the AC-SES compared to the BMS at both 30 and 90 days after implantation. Biocompatible, rapidly absorbable stent coatings enable the matching of drug release with coating erosion and provide for the controlled migration of coating material into tissue to reduce vicissitudes in drug tissue levels, optimizing efficacy and reducing potential toxicity. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Long range node-strut analysis of trabecular bone microarchitecture

    DEFF Research Database (Denmark)

    Schmah, Tanya; Marwan, Norbert; Thomsen, Jesper Skovhus

    2011-01-01

    PURPOSE: We present a new morphometric measure of trabecular bone microarchitecture, called mean node strength (NdStr), which is part of a newly developed approach called long range node-strut analysis. Our general aim is to describe and quantify the apparent "latticelike" microarchitecture of th...

  5. Optical Coherence Tomography Findings in Patients With Stent Thrombosis.

    Science.gov (United States)

    Cuesta, Javier; Rivero, Fernando; Bastante, Teresa; García-Guimaraes, Marcos; Antuña, Paula; Alvarado, Teresa; Navarrete, Gonzalo; Benedicto, Amparo; Alfonso, Fernando

    2017-12-01

    Stent thrombosis (ST) is a rare but potentially serious complication. Optical coherence tomography (OCT) provides high-resolution images and additional information to angiography in the study of this event. Prospective study of patients with ST undergoing reintervention with OCT imaging. The study included a total of 40 consecutive patients with ST. Mean age was 69 ± 13 years and 83% were male. Early ST (≤ 30 days) was observed in 16 patients and late ST (> 30 days) in 24 patients. Stent thrombosis occurred in 17 bare-metal stents and 23 drug-eluting stents. In 34 patients (85%), adequate OCT images were obtained at the time of the ST. The predominant mechanism in early ST was stent malapposition (39%). In late ST, high frequencies of uncovered (46%) and malapposed struts (17%) were observed, especially in patients with drug-eluting stents. Furthermore, the presence of neoatherosclerosis was very high (67%) in patients with late ST. After intervention, improvements were observed in malapposition length and the amount of residual thrombus. OCT allows identification of the underlying mechanisms potentially involved in ST. This imaging modality is helpful in guiding reintervention in these patients, which improves the area and length of malapposition, as well as the maximal residual thrombus area. Copyright © 2017 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

  6. 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.

  7. Evaluating the interaction of a tracheobronchial stent in an ovine in-vivo model.

    Science.gov (United States)

    McGrath, Donnacha J; Thiebes, Anja Lena; Cornelissen, Christian G; O'Brien, Barry; Jockenhoevel, Stefan; Bruzzi, Mark; McHugh, Peter E

    2018-04-01

    Tracheobronchial stents are used to restore patency to stenosed airways. However, these devices are associated with many complications such as stent migration, granulation tissue formation, mucous plugging and stent strut fracture. Of these, granulation tissue formation is the complication that most frequently requires costly secondary interventions. In this study a biomechanical lung modelling framework recently developed by the authors to capture the lung in-vivo stress state under physiological loading is employed in conjunction with ovine pre-clinical stenting results and device experimental data to evaluate the effect of stent interaction on granulation tissue formation. Stenting is simulated using a validated model of a prototype covered laser-cut tracheobronchial stent in a semi-specific biomechanical lung model, and physiological loading is performed. Two computational methods are then used to predict possible granulation tissue formation: the standard method which utilises the increase in maximum principal stress change, and a newly proposed method which compares the change in contact pressure over a respiratory cycle. These computational predictions of granulation tissue formation are then compared to pre-clinical stenting observations after a 6-week implantation period. Experimental results of the pre-clinical stent implantation showed signs of granulation tissue formation both proximally and distally, with a greater proximal reaction. The standard method failed to show a correlation with the experimental results. However, the contact change method showed an apparent correlation with granulation tissue formation. These results suggest that this new method could be used as a tool to improve future device designs.

  8. Chemico-physical characterisation and in vivo biocompatibility assessment of DLC-coated coronary stents.

    Science.gov (United States)

    Castellino, Micaela; Stolojan, Vlad; Virga, Alessandro; Rovere, Massimo; Cabiale, Karine; Galloni, Marco R; Tagliaferro, Alberto

    2013-01-01

    The vast majority of stent thrombosis occurs in the acute and sub-acute phases and is more common in patients with acute coronary syndromes, due to the thrombotic milieu where stent struts are positioned. Stent thrombosis is likely due to incomplete tissue coverage of metallic stents as the contact between metallic stents and blood elements may lead to platelet adhesion and trigger vessel thrombosis. If a stent is covered after 7 days, the risk that it will be found uncovered at later stages is very low (DLC) coatings, deposited by physical vapour deposition, promote rapid endothelisation of coronary stent devices, with very low platelets activation, reducing thrombotic clots. We relate these behaviours to the surface and bulk material properties of the DLC films, subjected to a comprehensive chemico-physical characterisation using several techniques (X-ray photoelectron spectroscopy, atomic force microscopy, field-emission scanning electron microscope, transmission electron microscopy combined with electron energy loss spectroscopy, Raman and dispersive X-ray spectroscopy). In vivo studies, conducted on 24 pigs, have shown complete endothelisation after 7 days, with no fibrin mesh and with only rare monocytes scattered on the endothelial layer while 30 and 180 days tests have shown reduced inflammatory activation and a complete stabilisation of the vessel healing, with a minimal neointimal proliferation. The integral and permanent DLC film coating improves haemo- and bio-compatibility and leads to an excellent early vessel healing of the stent whilst the extremely thin strut thickness reduces the amount of late neointima and consequently the risk of late restenosis. These data should translate into a reduced acute and sub-acute stent thrombosis.

  9. Computational simulation of multi-strut central lobed injection of hydrogen in a scramjet combustor

    Directory of Open Access Journals (Sweden)

    Gautam Choubey

    2016-09-01

    Full Text Available Multi-strut injection is an approach to increase the overall performance of Scramjet while reducing the risk of thermal choking in a supersonic combustor. Hence computational simulation of Scramjet combustor at Mach 2.5 through multiple central lobed struts (three struts have been presented and discussed in the present research article. The geometry and model used here is slight modification of the DLR (German Aerospace Center scramjet model. Present results show that the presence of three struts injector improves the performance of scramjet combustor as compared to single strut injector. The combustion efficiency is also found to be highest in case of three strut fuel injection system. In order to validate the results, the numerical data for single strut injection is compared with experimental result which is taken from the literature.

  10. 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

  11. Improved Hypersonic Inlet Performance Using Validated Strut Compression Designs

    Science.gov (United States)

    Bulman, M. J.; Stout, P. W.; Fernandez, R.

    1997-01-01

    Aerojet is currently executing two Strutjet propulsion contracts: one a Rocket Based Combined Cycle (RBCC) engine for a NASA-Marshall Space Flight Center (MSFC) Advanced Reusable Transportation Technology (ARTT) program, the second a Dual Mode Ram/Scramjet engine for a USAF Wright Laboratories Storable Fuel Scramjet Flow Path Concepts program. The engines employed in both programs operate at supersonic and low hypersonic speeds and use inlets employing forebody external and sidewall compression. Aerojet has developed and validated a successful design methodology applicable to these inlet types. Design features include an integrated vehicle forebody, external side compression struts, strut sidewall and throat bleed, a throat shock trap, and variable geometry internal contraction. Computation Fluid Dynamic (CFD) predictions and test data show these inlets allow substantially increased flow turning angles over other designs. These increased flow turning angles allow shorter and lighter engines than current designs, which in turn enables higher performing vehicles with broad operating characteristics. This paper describes the designs of two different inlets evaluated by the NASA-MSFC and USAF programs, discusses the results of wind tunnel tests performed by NASA-Lewis Research Center, and provides correlations of test data with CFD predictions. Parameters of interest include low Mach number starting capability, start sensitivity as a function of back pressure at various contraction ratios, flow turning angles, strut and throat bleed effects, and pressure recovery at various Mach numbers.

  12. Vascular stents: Coupling full 3-D with reduced-order structural models

    International Nuclear Information System (INIS)

    Avdeev, I; Shams, M

    2010-01-01

    Self-expanding nitinol stents are used to treat peripheral arterial disease. The peripheral arteries are subjected to a combination of mechanical forces such as compression, torsion, bending, and contraction. Most commercially available peripheral self-expanding stents are composed of a series of sub-millimeter V-shaped struts, which are laser-cut from a nitinol tube and surface-treated for better fatigue performance. The numerical stent models must accurately predict location and distribution of local stresses and strains caused by large arterial deformations. Full 3-D finite element non-linear analysis of an entire stent is computationally expensive to the point of being prohibitive, especially for longer stents. Reduced-order models based on beam or shell elements are fairly accurate in capturing global deformations, but are not very helpful in predicting stent failure. We propose a mixed approach that combines the full 3-D model and reduced-order models. Several global-local, full 3-D/reduced-order finite element models of a peripheral self-expanding stent were validated and compared with experimental data. The kinematic constraint method used to couple various elements together was found to be very efficient and easily applicable to commercial FEA codes. The proposed mixed models can be used to accurately predict stent failure based on realistic (patient-specific), non-linear kinematic behavior of peripheral arteries.

  13. Nonlinear process in the mode transition in typical strut-based and cavity-strut based scramjet combustors

    Science.gov (United States)

    Yan, Li; Liao, Lei; Huang, Wei; Li, Lang-quan

    2018-04-01

    The analysis of nonlinear characteristics and control of mode transition process is the crucial issue to enhance the stability and reliability of the dual-mode scramjet engine. In the current study, the mode transition processes in both strut-based combustor and cavity-strut based combustor are numerically studied, and the influence of the cavity on the transition process is analyzed in detail. The simulations are conducted by means of the Reynolds averaged Navier-Stokes (RANS) equations coupled with the renormalization group (RNG) k-ε turbulence model and the single-step chemical reaction mechanism, and this numerical approach is proved to be valid by comparing the predicted results with the available experimental shadowgraphs in the open literature. During the mode transition process, an obvious nonlinear property is observed, namely the unevenly variations of pressure along the combustor. The hysteresis phenomenon is more obvious upstream of the flow field. For the cavity-strut configuration, the whole flow field is more inclined to the supersonic state during the transition process, and it is uneasy to convert to the ramjet mode. In the scram-to-ram transition process, the process would be more stable, and the hysteresis effect would be reduced in the ram-to-scram transition process.

  14. Toxic vessel reaction to an absorbable polymer-based paclitaxel-eluting stent in pig coronary arteries.

    Science.gov (United States)

    Jabara, Refat; Chronos, Nicolas; Tondato, Fernando; Conway, Damian; Molema, Warner; Park, Kenneth; Mabin, Tom; King, Spencer; Robinson, Keith

    2006-08-01

    The goal of this study was to evaluate a new drug-eluting stent (DES) comprising a bioabsorbable polymer eluting a moderate dose of paclitaxel in a clinically relevant animal model. Although DES limit restenosis, adverse vascular pathologies and toxicities continue to be of major concern. Optimization of DES components, especially completely absorbable polymers, may reduce these toxicities. Bare-metal (BM), absorbable polymer coating only (POLY), and polymer-based paclitaxel-eluting (PACL) stents were implanted in porcine coronary arteries using intravascular ultrasound (IVUS) to optimize stent apposition. The dose density of paclitaxel was 0.30-0.35 mcg/mm2, with in vitro elution studies demonstrating a gradual elution over 6-8 weeks. The animals were terminated at 1 week, 1 month and 3 months. Histopathologic and histomorphometric analyses were perform. The arteries with PACL showed extensive smooth muscle cell necrosis at 1 week and poor apposition of stent struts at 1 month (malapposition measured as gap width between strut and internal elastic lamina), with greater gap width compared to the BM and POLY groups (0.22 mm +/- 0.02 vs. 0.03 mm +/- 0.02 and 0.02 mm +/- 0.01, respectively; p stent malapposition and late neointimal thickening. Since the therapeutic window for paclitaxel may be narrower than currently inferred, thorough preclinical testing coupled with the polymer development process for stents eluting paclitaxel is needed.

  15. Yield Strength Testing in Human Cadaver Nasal Septal Cartilage and L-Strut Constructs.

    Science.gov (United States)

    Liu, Yuan F; Messinger, Kelton; Inman, Jared C

    2017-01-01

    To our knowledge, yield strength testing in human nasal septal cartilage has not been reported to date. An understanding of the basic mechanics of the nasal septum may help surgeons decide how much of an L-strut to preserve and how much grafting is needed. To determine the factors correlated with yield strength of the cartilaginous nasal septum and to explore the association between L-strut width and thickness in determining yield strength. In an anatomy laboratory, yield strength of rectangular pieces of fresh cadaver nasal septal cartilage was measured, and regression was performed to identify the factors correlated with yield strength. To measure yield strength in L-shaped models, 4 bonded paper L-struts models were constructed for every possible combination of the width and thickness, for a total of 240 models. Mathematical modeling using the resultant data with trend lines and surface fitting was performed to quantify the associations among L-strut width, thickness, and yield strength. The study dates were November 1, 2015, to April 1, 2016. The factors correlated with nasal cartilage yield strength and the associations among L-strut width, thickness, and yield strength in L-shaped models. Among 95 cartilage pieces from 12 human cadavers (mean [SD] age, 67.7 [12.6] years) and 240 constructed L-strut models, L-strut thickness was the only factor correlated with nasal septal cartilage yield strength (coefficient for thickness, 5.54; 95% CI, 4.08-7.00; P cadaver nasal septal cartilage, L-strut thickness was significantly associated with yield strength. In a bonded paper L-strut model, L-strut thickness had a more important role in determining yield strength than L-strut width. Surgeons should consider the thickness of potential L-struts when determining the amount of cartilaginous septum to harvest and graft. NA.

  16. TIDES-ACS Trial: comparison of titanium-nitride-oxide coated bio-active-stent to the drug (everolimus)-eluting stent in acute coronary syndrome. Study design and objectives.

    Science.gov (United States)

    Colkesen, E B; Eefting, F D; Rensing, B J; Suttorp, M J; Ten Berg, J M; Karjalainen, P P; Van Der Heyden, J A

    2015-02-01

    Drug-eluting stents (DES), delivering antiproliferative drugs from a durable polymer, have shown to reduce in-stent restenosis after percutaneous coronary intervention (PCI) compared to bare-metal stents (BMS). However, they have been associated with a hypersensitivity reaction, delayed healing, and incomplete endothelialization, which may contribute to an increased risk of late stent thrombosis. Consequently, a prolonged duration of dual antiplatelet therapy (DAPT) is needed, with an increased risk of bleeding complication. A number of stent technologies are being developed in an attempt to modify late thrombotic events and DAPT duration. The Optimax™ stent is such a novel, next generation bioactive stent (BAS), in which a thicker layer of titanium-nitride-oxide coating is inserted over the stent struts. The rationale of this is to obtain more efficient and rapid vascular healing at the site of the stent implantation. The aim of TIDES-ACS Trial is to compare clinical outcome in patients presenting with ACS, treated with PCI using Optimax-BAS versus Synergy™-EES. Second objective is to explore whether the Optimax™-BAS use is superior compared with Synergy™-EES use with respect of hard end points (cardiac death, myocardial infarction [MI] and major bleeding). A prospective, randomized, multicenter trial (ClinicalTrials.gov Identifier: NCT02049229), will be conducted in interventional centres in Finland (six centres), France (five centres) and Holland (two centres), including a total of 1800 patients.

  17. Six-strut arrangements for cartesian movements of mirrors

    International Nuclear Information System (INIS)

    Noll, T.; Zeschke, Th.; Reichardt, G.; Lammert, H.; Gudat, W.

    2001-01-01

    At BESSY a new six-strut arrangement for general small travel mirror adjustment mechanisms has been developed. This patented (Patent DE 10042802.5) arrangement allows very simple movements in all six linear and rotational degrees of freedom. The movements of the mirror are simply determined by moving either one drive, or up to three drives by the same amount. The first mirror adjustment systems of this design is successfully in operation since the start of BESSY II. Their performance and reliability is very satisfactory. This contribution will present the concepts

  18. Portal WEB 2.0. utilizando Framework Struts

    OpenAIRE

    Palacín Mateo, Manuel

    2007-01-01

    El propósito de este proyecto es la implementación de un portal interactivo de contactos utilizando las tecnologías J2EE mediante Struts y siguiendo la tendencia Web 2.0. Previo a esta implementación se ha hecho una valoración del mercado actual de los portales de contactos y se han evaluado los servicios que ofrecen para posteriormente añadirlos a la demostración tecnológica. Tras esto se ha explicado lo que es la tendencia Web 2.0. Finalmente se han evaluado las diferentes opciones o tec...

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

    DEFF Research Database (Denmark)

    Sabaté, Manel; Windecker, Stephan; Iñiguez, Andres

    2015-01-01

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

  20. Randomized comparison of a sirolimus-eluting Orsiro stent with a biolimus-eluting Nobori stent in patients treated with percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Jensen, Lisette Okkels; Thayssen, Per; Maeng, Michael

    2015-01-01

    BACKGROUND: Third-generation coronary drug-eluting stents (DES) with biodegradable polymers have been designed to improve safety and efficacy. We designed a large scale registry-based randomized clinical trial to compare 2 third-generation DES: a thin strut, cobalt-chromium DES with silicon carbide......-coating releasing sirolimus from a biodegradable polymer (O-SES, Orsiro; Biotronik, Bülach, Switzerland) with the stainless steel biodegradable polymer biolimus-eluting Nobori stents (N-BES, Nobori; Terumo, Tokyo, Japan) in an all-comer patient population. DESIGN: The multicenter SORT OUT VII trial (NCT01879358...... will be used. An event rate of 6.5% is assumed in each stent group. With a sample size of 1,157 patients in each treatment arm, a 2-group large-sample normal approximation test of proportions with a 1-sided 5% significance level will have 90% power to detect noninferiority of the O-SES compared with the N...

  1. Flow Velocities After Carotid Artery Stenting: Impact of Stent Design. A Fluid Dynamics Study in a Carotid Artery Model with Laser Doppler Anemometry

    International Nuclear Information System (INIS)

    Greil, Oliver; Kleinschmidt, Thomas; Weiss, Wolfgang; Wolf, Oliver; Heider, Peter; Schaffner, Silvio; Gianotti, Marc; Schmid, Thomas; Liepsch, Dieter; Berger, Hermann

    2005-01-01

    Purpose. To study the influence of a newly developed membrane stent design on flow patterns in a physiologic carotid artery model. Methods. Three different stents were positioned in silicone models of the carotid artery: a stainless steel stent (Wall-stent), a nitinol stent (SelfX), and a nitinol stent with a semipermeable membrane (MembraX). To increase the contact area of the membrane with the vessel wall, another MembranX model was modified at the outflow tract. The membrane consists of a biocompatible silicone-polyurethane copolymer (Elast-Eon) with a pore size of 100 μm. All stents were deployed across the bifurcation and the external carotid artery origin. Flow velocity measurements were performed with laser Doppler anemometry (LDA), using pulsatile flow conditions (Re = 220; flow 0.39 l/min; flow rate ratio ICA:ECA = 70:30) in hemodynamically relevant cross-sections. The hemodynamic changes were analyzed by comparing velocity fluctuations of corresponding flow profiles. Results. The flow rate ratio ICA:ECA shifted significantly from 70/30 to 73.9/26.1 in the MembraX and remained nearly unchanged in the SelfX and Wallstent. There were no changes in the flow patterns at the inflow proximal to the stents. In the stent no relevant changes were found in the SelfX. In the Wallstent the separation zone shifted from the orifice of the ICA to the distal end of the stent. Four millimeters distal to the SelfX and the Wallstent the flow profile returned to normal. In the MembraX an increase in the central slipstreams was found with creation of a flow separation distal to the stent. With a modification of the membrane this flow separation vanished. In the ECA flow disturbances were seen at the inner wall distal to the stent struts in the SelfX and the Wallstent. With the MembraX a calming of flow could be observed in the ECA with a slight loss of flow volume. Conclusions. Stent placement across the carotid artery bifurcation induces alterations of the physiologic flow

  2. High-resolution 3D X-ray imaging of intracranial nitinol stents

    International Nuclear Information System (INIS)

    Snoeren, Rudolph M.; With, Peter H.N. de; Soederman, Michael; Kroon, Johannes N.; Roijers, Ruben B.; Babic, Drazenko

    2012-01-01

    To assess an optimized 3D imaging protocol for intracranial nitinol stents in 3D C-arm flat detector imaging. For this purpose, an image quality simulation and an in vitro study was carried out. Nitinol stents of various brands were placed inside an anthropomorphic head phantom, using iodine contrast. Experiments with objects were preceded by image quality and dose simulations. We varied X-ray imaging parameters in a commercially interventional X-ray system to set 3D image quality in the contrast-noise-sharpness space. Beam quality was varied to evaluate contrast of the stents while keeping absorbed dose below recommended values. Two detector formats were used, paired with an appropriate pixel size and X-ray focus size. Zoomed reconstructions were carried out and snapshot images acquired. High contrast spatial resolution was assessed with a CT phantom. We found an optimal protocol for imaging intracranial nitinol stents. Contrast resolution was optimized for nickel-titanium-containing stents. A high spatial resolution larger than 2.1 lp/mm allows struts to be visualized. We obtained images of stents of various brands and a representative set of images is shown. Independent of the make, struts can be imaged with virtually continuous strokes. Measured absorbed doses are shown to be lower than 50 mGy Computed Tomography Dose Index (CTDI). By balancing the modulation transfer of the imaging components and tuning the high-contrast imaging capabilities, we have shown that thin nitinol stent wires can be reconstructed with high contrast-to-noise ratio and good detail, while keeping radiation doses within recommended values. Experimental results compare well with imaging simulations. (orig.)

  3. Carotid Angioplasty and Stenting

    Science.gov (United States)

    Carotid angioplasty and stenting Overview Carotid angioplasty (kuh-ROT-id AN-jee-o-plas-tee) and stenting ... to better see and examine the blood vessels. Food and medications You'll receive instructions on what ...

  4. The OCT-ORION Study: A Randomized Optical Coherence Tomography Study Comparing Resolute Integrity to Biomatrix Drug-Eluting Stent on the Degree of Early Stent Healing and Late Lumen Loss.

    Science.gov (United States)

    Lee, Stephen W L; Tam, Frankie C C; Lam, Simon C C; Kong, Shun-Ling; Shea, Catherine P; Chan, Kelvin K W; Wong, Michael K L; Chan, Michael P H; Wong, Anthony Y T; Yung, Arthur S Y; Lam, Yui-Ming; Zhang, Lei-Wei; Wu, Karl K Y; Mintz, Gary S; Maehara, Akiko

    2018-04-01

    Durable polymers used in drug-eluting stents are considered a potential cause of hypersensitivity inflammatory response adversely affecting stent healing. Using a sequential follow-up with optical coherence tomography, we compared the differences in healing profiles of 2 drug-eluting stents with a biodegradable or durable polymer. Sixty patients with multivessel disease were prospectively enrolled to receive both study stents, which were randomly assigned to 2 individual vessels, a Resolute Integrity zotarolimus-eluting stent with a durable BioLinx polymer and a BioMatrix NeoFlex Biolimus A9-eluting stent with a biodegradable polylactic acid polymer. Optical coherence tomography was performed at baseline, then in 5 randomly assigned monthly groups at 2 to 6 months, and at 9 months in all patients. The primary end point was the difference in optical coherence tomography strut coverage at 9 months. Key secondary end points included angiographic late lumen loss and composite major adverse cardiac events (cardiac death, myocardial infarction, target lesion revascularization, and definite or probable stent thrombosis) at 9 months. Resolute Integrity zotarolimus-eluting stent showed significantly better strut coverage than BioMatrix NeoFlex Biolimus A9-eluting stent at 2 to 6 months ( P <0.001) and less variance of percent coverage at 9 months, 99.7% (interquartile range, 99.1-100) versus 99.6% (interquartile range, 96.8-99.9; difference, 0.10; 95% confidence interval, 0.00-1.05; P <0.001). No significant difference was observed in major adverse cardiac events or angiographic end points. Despite having a durable polymer, Resolute Integrity zotarolimus-eluting stent exhibited better strut coverage than BioMatrix NeoFlex Biolimus A9-eluting stent having a biodegradable polymer; both showed similar antiproliferative efficacy. This novel, longitudinal, sequential optical coherence tomography protocol using each patient as own control could achieve conclusive results in small

  5. Magnetic stents retain nanoparticle-bound antirestenotic drugs transported by lipid microbubbles.

    Science.gov (United States)

    Räthel, T; Mannell, H; Pircher, J; Gleich, B; Pohl, U; Krötz, F

    2012-05-01

    Coating coronary stents with antirestenotic drugs revolutionized interventional cardiology. We developed a system for post-hoc drug delivery to uncoated stents. We coupled rapamycin or a chemically similar fluorescent dye to superparamagnetic nanoparticles. The antiproliferative activity of rapamycin coupled to nanoparticles was confirmed in vitro in primary porcine vascular cells. The particles were then incorporated into lipid based microbubbles. Commercially available stents were made magnetizable by nickel plating and used to induce strong field gradients in order to capture magnetic microbubbles from flowing liquids when placed in an external magnetic field. Nanoparticle bound Rapamycin dose dependently inhibited cell proliferation in vitro. Magnetic microcbubbles carrying coated nanoparticles were caught by magnets placed external to a flow-through tube. Plating commercial stents with nickel resulted in increased deposition at stent struts and allowed for widely increased distance of external magnets. Deposition depended on circulation time and velocity and distance of magnets. Deposited microbubbles were destroyed by ultrasound and delivered their cargo to targeted sites. Drugs can be incorporated into nanoparticle loaded microbubbles and thus be delivered to magnetizable stents from circulating fluids by applying external magnetic fields. This technology could allow for post-hoc drug coating of already implanted vascular stents.

  6. Development of AISI 316L stainless steel coronary stent

    Science.gov (United States)

    García-López, Erika; Siller, Héctor R.; Rodríguez, Ciro A.

    2018-02-01

    Coronary stents are manufactured through a sequence of processes and each step demands the process control to assure surface quality. This study is focused on the influence of laser cutting parameters and electropolishing on average surface roughness and back wall dross percentage for fiber laser cutting of AISI 316L coronary struts. A preliminary test and a design of experiments (DOE) were implemented to determine the limiting cutting conditions and the effect of these parameters on quality indicators. Preliminary results identify four cutting zones from a non-cut zone to a burned zone, in a frequency range between 1000 and 1500 Hz and a peak power between 160 to 180 W for clean cuts. From the DOE results, several interactions between factors were observed; however, a laser frequency of 1000 to 1500 Hz and a cutting speed of 250 mm/min minimize the backwall dross percentage and the surface roughness to values less than 2% and 0.9 μm, respectively. After the laser conditions selection, coronary stents were manufactured and electropolished to reduce the surface roughness on the strut edge. Electropolishing results indicate a surface roughness reduction from 0.9 μm to 0.3 μm after 300 s of electropolishing time.

  7. Investigation of mixing characteristics in strut injectors using modal decomposition

    Science.gov (United States)

    Soni, Rahul Kumar; De, Ashoke

    2018-01-01

    Effect of a large-scale vortical structure on mixing and spreading of a shear layer is numerically investigated. Two strut configurations, namely, straight and tapered struts at two convective Mach numbers (Mc = 1.4 and 0.37) for two jet heights (0.6 and 1 mm) are investigated. The hydrogen jet is injected through a two-dimensional slot in oncoming coflow at Mach 2. An excellent agreement between simulated and experimental data is witnessed, whereas the instantaneous data reveal the presence of various large-scale structures in the flow field. From the instantaneous field, it becomes apparent that both the geometries have different vortical breakdown locations. It is also noticed that an early onset of vortex breakdown manifests itself into the mixing layer thickness enhancement, the effect of which is reflected in overall mixing characteristics. It becomes evident that the shear strength plays an important role in the near field mixing. The higher shear strength promotes the generation of large vortices. The analysis shows that the SS-0.6 case offers highest mixing efficiency being dominated by relatively large-scale structures. Eigenmodes obtained through Proper Orthogonal Decomposition (POD) confirm the presence of dominating structures and shed light into the series of events involved in vortex pairing/merging and breakdown. Dynamic modal decomposition also strengthens the observation made through the POD.

  8. [Strut fracture of a convex-concave 60 degree Björk-Shiley mitral valve prosthesis 5 years after implantation--metallurgic analysis of the prosthesis strut].

    Science.gov (United States)

    Lemke, B; Rathmann, J; Wiebe, V; Witzel, U

    1991-08-01

    Acute mechanical failure of prosthetic heart valves is rare, but associated with high mortality when occurring. For convexo-concave Björk-Shiley prostheses only fractures of the outlet strut are reported. We present a case of lethal mechanical complication 5 years after implantation. By additional metallurgic analysis we were able to identify a sequential course of the outlet strut fracture. This could lead to new approaches for early detection of this complication.

  9. Fuel/Air Mixing Characteristics of Strut Injections for Scramjet Combustor Applications (Postprint)

    Science.gov (United States)

    2008-08-01

    regions, and drag will be increased, as suggested by Povinelli .26 Both the total pressure recovery and mixing efficiency for the forward-swept strut are...Experimental Study of Cavity-Strut Combustion in Supersonic Flow,” AIAA Paper 2007-5394, 2007. 26. Povinelli , L.A., “Aerodynamic Drag and Fuel Spreading

  10. Stress analysis of two-dimensional cellular materials with thick cell struts

    International Nuclear Information System (INIS)

    Lim, Do Hyung; Kim, Han Sung; Kim, Young Ho; Kim, Yoon Hyuk; Al-Hassani, S.T.S.

    2008-01-01

    Finite element analyses (FEA) were performed to thoroughly validate the collapse criteria of cellular materials presented in our previous companion paper. The maximum stress (von-Mises stress) on the cell strut surface and the plastic collapse stress were computed for two-dimensional (2D) cellular materials with thick cell struts. The results from the FEA were compared with those from theoretical criteria of authors. The FEA results were in good agreement with the theoretical results. The results indicate that when bending moment, axial and shear forces are considered, the maximum stress on the strut surface gives significantly different values in the tensile and compressive parts of the cell wall as well as in the two loading directions. Therefore, for the initial yielding of ductile cellular materials and the fracture of brittle cellular materials, in which the maximum stress on the strut surface is evaluated, it is necessary to consider not only the bending moment but also axial and shear forces. In addition, this study shows that for regular cellular materials with the identical strut geometry for all struts, the initial yielding and the plastic collapse under a biaxial state of stress occur not only in the inclined cell struts but also in the vertical struts. These FEA results support the theoretical conclusion of our previous companion paper that the anisotropic 2D cellular material has a truncated yield surface not only on the compressive quadrant but also on the tensile quadrant

  11. 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

  12. Investigation of strut-ramp injector in a Scramjet combustor: Effect of strut geometry, fuel and jet diameter on mixing characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Soni, Rahul Kumar; De, Ashoke De [Indian Institute of Technology Kanpur, Kanpur (India)

    2017-03-15

    The strut-based injector has been found to be one of the most promising injector designs for a supersonic combustor, offering enhanced mixing of fuel and air. The mixing and flow field characteristics of the straight (SS) and Tapered strut (TS), with fixed ramp angle and height at free stream Mach number 2 in conjunction with fuel injection at Mach 2.3 have been investigated numerically and reported. In the present investigation, hydrogen (H{sub 2}) and ethylene (C{sub 2}H{sub 4}) are injected in oncoming supersonic flow from the back of the strut, where jet to free stream momentum ratio is maintained at 0.79 and 0.69 for H2 and C{sub 2}H{sub 4}, respectively. The predicted wall static pressure and species mole fractions at various downstream locations are compared with the experimental data for TS case with 0.6 mm jet diameter and found to be in good agreement. Further, the effect of jet diameter and strut geometry on the near field mixing in strut ramp configuration is discussed for both the fuels. The numerical results are assessed based on various parameters for the performance evaluation of different strut ramp configurations. The SS configuration for both the injectant has been found to be an optimum candidate; also it is observed that for higher jet diameter larger combustor length is required to achieve satisfactory near field mixing.

  13. A Dedicated Z-Stent for Acquired Saber-Sheath Tracheobronchomalacia

    International Nuclear Information System (INIS)

    Kishi, Kazushi; Fujimoto, Hisashi Kobayashi; Sonomura, Tetsuo; Uetani, Kosaku; Nishida, Norifumi; Ohata, Masahiro; Sato, Morio; Yamada, Ryusaku

    1997-01-01

    The tracheobronchial lumen has a continuous horseshoe arch morphology. We formed Z-stents accordingly to support the weakened cartilagenous portions. With this type of stent we treated a patient with acquired saber-sheath type tracheobronchomalacia (TBM), Rayl's type II, Johnson's grade III, whose condition was aggravated even under positive end expiratory pressure (PEEP) therapy. The patient improved gradually. No immediate complication was observed. Bronchofiberscopic examination revealed that the tracheobronchial arcade was closely strut-braced and showed no expiratory collapse. Six months later, when the patient was intubated due to asthmatic attacks, tissue ingrowth through the stent was found and removed. There was no recurrence of TBM. The patient died 2 years later of pneumoconiosis

  14. Serial assessment by optical coherence tomography of early and late vascular responses after implantation of an absorbable-coating Sirolimus-Eluting stent (from the first-in-human DESSOLVE I trial).

    Science.gov (United States)

    Attizzani, Guilherme F; Bezerra, Hiram G; Ormiston, John; Wang, Wei; Donohoe, Dennis; Wijns, William; Costa, Marco A

    2013-11-15

    The initial enthusiasm caused by the potent antirestenotic effect of early generation drug-eluting stents was recently plagued by concerns regarding their safety profile. Investigators worldwide were stimulated, therefore, to seek for improvement in drug-eluting stent technology, such as eliminating their permanent polymer blamed for vascular inflammation and delayed healing. Optical coherence tomography (OCT) assessments of stent-vessel interactions are used as a surrogate for vessel healing after DES implantation. Herewith, we report serial OCT assessments of vascular reactions to the implantation of a novel absorbable polymer sirolimus-eluting stent (MiStent). In total, 30 patients were included. At 4-, 6-, and 8-month follow-up, different groups of 10 patients underwent OCT imaging, whereas all the patients had OCT assessments scheduled at 18-month follow-up. A total of 13,569 stent struts were analyzed. Low rates of uncovered (14.34 ± 15.35%, 6.62 ± 10.93%, 3.51 ± 2.87%, and 0.84 ± 1.15%, respectively, p stent struts coupled with thin and increasingly homogenous neointimal proliferation were demonstrated. Neointimal area increased from 4- to 8-month follow-up (0.46 ± 0.29 and 1.12 ± 0.73 mm(2), respectively, p stent struts (8.8%, 3.1%, 0.3%, and 0%, respectively, p absorbable polymer sirolimus-eluting stent-vessel interactions up to 18-month follow-up. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Analytical prediction of the unsteady lift on a rotor caused by downstream struts

    Science.gov (United States)

    Taylor, A. C., III; Ng, W. F.

    1987-01-01

    A two-dimensional, inviscid, incompressible procedure is presented for predicting the unsteady lift on turbomachinery blades caused by the upstream potential disturbance of downstream flow obstructions. Using the Douglas-Neumann singularity superposition potential flow computer program to model the downstream flow obstructions, classical equations of thin airfoil theory are then employed, to compute the unsteady lift on the upstream rotor blades. The method is applied to a particular geometry which consists of a rotor, a downstream stator, and downstream struts which support the engine casing. Very good agreement between the Douglas-Neumann program and experimental measurements was obtained for the downstream stator-strut flow field. The calculations for the unsteady lift due to the struts were in good agreement with the experiments in showing that the unsteady lift due to the struts decays exponentially with increased axial separation of the rotor and the struts. An application of the method showed that for a given axial spacing between the rotor and the strut, strut-induced unsteady lift is a very weak function of the axial or circumferential position of the stator.

  16. Noninvasive inductive stent heating: alternative approach to prevent instent restenosis?

    Science.gov (United States)

    Floren, Michael G; Günther, Rolf W; Schmitz-Rode, Thomas

    2004-05-01

    extensive necrosis area around the stent. Treatment time and stent temperature were optimized in further tests. Selective noninvasive energy transfer to coronary stainless steel stents by inductive heating is possible within a wide range of power. By thermal conduction, vital cells close to the stent struts can be affected. The frequency of 200 kHz turned out to be favorable. There is still room for further optimization of energy dosage with regard to material and stent design, to induce controlled cell death. The method has potential to serve as an alternative approach for prevention of instent restenosis.

  17. Quantitative analysis of the side-branch orifice after bifurcation stenting using en-face processing of OCT images: a comparison between Xience V and Resolute Integrity stents.

    Science.gov (United States)

    Minami, Yoshiyasu; Wang, Zhao; Aguirre, Aaron D; Lee, Stephen; Uemura, Shiro; Soeda, Tsunenari; Vergallo, Rocco; Raffel, Owen C; Barlis, Peter; Itoh, Tomonori; Lee, Hang; Fujimoto, James; Jang, Ik-Kyung

    2016-01-01

    Methods for intravascular assessment of the side-branch (SB) orifice after stenting are not readily available. The aim of this study was to assess the utility of an en-face projection processing for optical coherence tomography (OCT) images for SB evaluation. Measurements of the SB orifice obtained using en-face OCT images were validated using a phantom model. Linear regression modeling was applied to estimated area measurements made on the en-face images. The SB orifice was then analyzed in 88 patients with bifurcation lesions treated with either Xience V (everolimus-eluting stent) or Resolute Integrity [zotarolimus-eluting stent (ZES)]. The SB orifice area (A) and the area obstructed by struts (B) were calculated, and the %open area was evaluated as (A-B)/A*100. Linear regression modeling demonstrated that the observed departures of the intercept and slope were not significantly different from 0 (-0.12 ± 0.22, P=0.59) and 1 (1.01 ± 0.06, R(2)=0.88, P=0.87), respectively. In cases without SB dilatation, the %open area was significantly larger in the everolimus-eluting stent group (n=25) than in the ZES group [n=32; 89.2% (83.7-91.3) vs. 84.3% (78.9-87.8), P=0.04]. A significant difference in %open area between cases with and those without SB dilatation was demonstrated in the ZES group [91.4% (86.1-94.0) vs. 84.3% (78.9-87.8), P=0.04]. The accuracy of SB orifice measurement on an en-face OCT image was validated using a phantom model. This novel approach enables quantitative evaluation of the differences in SB orifice area free from struts among different stent types and different treatment strategies in vivo.

  18. The SYNERGY biodegradable polymer everolimus eluting coronary stent: Porcine vascular compatibility and polymer safety study.

    Science.gov (United States)

    Wilson, Gregory J; Marks, Angela; Berg, Kimberly J; Eppihimer, Michael; Sushkova, Natalia; Hawley, Steve P; Robertson, Kimberly A; Knapp, David; Pennington, Douglas E; Chen, Yen-Lane; Foss, Aaron; Huibregtse, Barbara; Dawkins, Keith D

    2015-11-15

    SYNERGY is a novel platinum chromium alloy stent that delivers abluminal everolimus from an ultrathin poly-lactide-co-glycide (PLGA) biodegradable polymer. This study evaluated the in vivo degradation of the polymer coating, everolimus release time course, and vascular compatibility of the SYNERGY stent. SYNERGY stents were implanted in arteries of domestic swine. Devices were explanted at predetermined time points (up to 120 days) and the extent of PLGA coating or everolimus remaining on the stents was quantified. Everolimus levels in the arterial tissue were also evaluated. A pathological analysis on coronary arteries of single and overlapping stents was performed at time points between 5 and 270 days. PLGA bioabsorption began immediately after implantation, and drug release was essentially complete by 90 days; PLGA absorption was substantially complete by 120 days (>90% of polymer was absorbed) leaving a bare metal SYNERGY stent. Vascular response was similar among SYNERGY and control stents (bare metal, polymer-only, and 3× polymer-only). Mild increases in para-strut fibrin were seen for SYNERGY at an early time point with no significant differences in all other morphological and morphometric parameters through 270 days or endothelial function (eNOS immunostaining) at 90 or 180 days. Inflammation was predominantly minimal to mild for all device types. In a swine model, everolimus was released by 90 days and PLGA bioabsorption was complete shortly thereafter. The SYNERGY stent and its biodegradable polymer, even at a 3× safety margin, demonstrated vascular compatibility similar to bare metal stent controls. © 2015 Wiley Periodicals, Inc.

  19. Modified nasolacrimal duct stenting

    International Nuclear Information System (INIS)

    Tian Min; Jin Mei; Chen Huanjun; Li Yi

    2008-01-01

    Objective: Traditional nasolacrimal duct stenting possesses some shortcoming including difficulty of pulling ball head guide wire from the nasal cavity with turbinate hypertrophy and nasal septal deviation. The new method of nose-oral tube track establishment can overcome the forementioned and increase the successful rate. Methods: 5 F catheter and arterial sheath were modified to be nasolacrimal duct stent delivery device respectively. Antegrade dacryocystography was taken firstly to display the obstructed site and followed by the modified protocol of inserting the guide wire through nasolacrimal duct and nasal cavity, and establishing the stent delivery track for retrograde stent placement. Results: 5 epiphora patients with failure implantation by traditional method were all succeeded through the modified stenting (100%). During 6-mouth follow-up, no serious complications and reocclusion occurred. Conclusion: The establishment of eye-nose-mouth-nose of external nasal guide wire track can improve the successful rate of nasolacrimal duct stenting. (authors)

  20. 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...

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

    Directory of Open Access Journals (Sweden)

    Teeuwen Koen

    2012-12-01

    tomography is performed in the first 60 randomized patients at 9 months to assess neointima thickness, percentage of neointima coverage, and stent strut malapposition and coverage. Personnel blinded to the allocated treatment will review all angiographic and optical coherence assessments. Secondary clinical endpoints include major adverse cardiac events, clinically driven target vessel revascularization, target vessel failure and stent thrombosis to 5-year clinical follow-up. An independent clinical event committee blinded to the allocated treatment will review all clinical events. Trial registration Clinical Trials.gov: NCT01516723. Patient recruitment started in February 2012.

  2. Beam Shear Design According to Eurocode 2 - Limitations for the Concrete Strut Inclinations

    DEFF Research Database (Denmark)

    Hagsten, Lars German; Hestbech, Lars; Fisker, Jakob

    2011-01-01

    and are presented. These beams are all designed to fail in shear and the shear reinforcement is designed for different values of the concrete strut inclinations (cot θ varies from 1.5 to 3.4). These tests indicate a clear connection between the values of the concrete strut inclinations and crack width in the SLS......The beam shear design method adopted in Eurocode 2 is based on a lower bound plastic solution. This method is combined with limitations on the concrete strut inclination, θ. These limitations are introduced to ensure acceptable crack width in the SLS. 7 full scale beams have been tested....... In cases where larger crack widths (w > 0.4 mm) can be accepted, larger values of the concrete strut inclinations can be chosen. This will lead to less shear reinforcements. The results are also compared with analytical analysis based on energy methods. At the SLS the beams are expected to be cracked...

  3. Study on durability and reliability of strut type suspension noise based on experimental methods

    International Nuclear Information System (INIS)

    Kim, Gu Gyong; Kang, Sung Su; Lee, Yong Jun; Park, Soon Cheol; Jung, Won Wook

    2012-01-01

    When cars are released from the factory, strut noises are very small and therefore it is difficult to perceive them. As the use time and travel distance increase, however, strut noises get larger so as to cause users much uneasiness. The noises generated at the field include engine noises and flow noises and therefore it is difficult to clearly discern the noises generated from struts. This study developed a test method which can reproduce field strut noises in the lab. Using the newly developed noise evaluation test, this study analyzed the effects that insulator performance degradation and failure can have on car noises. The study also confirmed that the insulator durability test by the simple back-and-forth motion cannot completely reflect the state of the parts failure in the field. Based on this, the study also confirmed that field noises can be reproduced through a durability test that considers heat aging

  4. Asymptomatic Strut Fracture in DeBakey-Surgitool Aortic Valves: Incidence, Management, and Metallurgic Aspects

    OpenAIRE

    Von Der Emde, Jürgen; Eberlein, Ulrich; Breme, Jürgen

    1990-01-01

    From August 1971 through November 1972, we implanted 62 Model 2 DeBakey-Surgitool aortic valve prostheses in 62 patients, 4 of whom later had clinically asymptomatic strut fractures. In 1 case, the patient died suddenly, and autopsy revealed detachment of the ball-cage; in each of the other 3 cases, fractures of 2 struts close to the base of the prosthesis were diagnosed fluoroscopically, and the patients underwent successful reoperation. The interval between implantation and reoperation rang...

  5. Outlet strut fracture and leaflet escape of Bjork-Shiley convexo-concave valve.

    Science.gov (United States)

    Uchino, Gaku; Yoshida, Hideo; Sakoda, Naoya; Hattori, Shigeru; Kawabata, Takuya; Saiki, Munehiro; Fujita, Yasufumi; Yunoki, Keiji; Hisamochi, Kunikazu; Mine, Yoshinari

    2017-06-01

    Prosthetic valve fracture is a serious complication and may arise in patient post-valve replacement. We experienced an outlet strut fracture and leaflet escape of a Bjork-Shiley convexo-concave valve. We performed an emergency redo mitral valve replacement and successfully retrieved the fractured strut and escaped leaflet from superficial femoral artery and the abdominal aorta. The patient showed an uneventful postoperative recovery.

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

    International Nuclear Information System (INIS)

    Han, Dong-Wook; Lee, Jun Jae; Jung, Duk-Young; Park, Jong-Chul; Hyon, Suong-Hyu

    2009-01-01

    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-ε-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.

  7. 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.

  8. StentBoost Visualization for the Evaluation of Coronary Stent Expansion During Percutaneous Coronary Interventions

    OpenAIRE

    Cura, Fernando; Albertal, Mariano; Candiello, Alfonsina; Nau, Gerardo; Bonvini, Victor; Tricherri, Hernan; Padilla, Lucio T.; Belardi, Jorge A.

    2013-01-01

    Introduction Inadequate stent implantation is associated with stent thrombosis and restenosis. StentBoost can enhance stent visualization and evaluate stent expansion. Currently, there are limited comparison studies between StentBoost and intravascular ultrasound (IVUS). We aimed to test the correlation and agreement between IVUS and StentBoost measurements. Methods From December 2010 to December 2011, 38 patients (54 stents) were analyzed using IVUS and StentBoost. Minimal stent diameter and...

  9. Predictors of early stent occlusion among plastic biliary stents.

    Science.gov (United States)

    Khashab, Mouen A; Kim, Katherine; Hutfless, Susan; Lennon, Anne Marie; Kalloo, Anthony N; Singh, Vikesh K

    2012-09-01

    A major disadvantage of plastic biliary stents is their short patency rates. The aim of this study was to identify predictors of early stent occlusion among patients receiving conventional plastic biliary stents. Early stent occlusion was defined as worsening cholestatic liver test results of a severity sufficiently significant to warrant ERCP with stent exchange prior to the planned stent exchange, or as symptoms of cholangitis. The association of cumulative stent diameter, demographics, stricture location, procedure indication, Charlson comorbidity index, history of prior early stent occlusion, presence of gallbladder, and performance of sphincteromy with the occurrence of early stent occlusion was studied using logistic regression and multivariate analysis. Our patient cohort comprised 343 patients (mean age 59.3 years) who underwent 561 ERCP procedures with the placement of one or more plastic biliary stents (mean number of stents per procedure 1.2, mean total diameter of stents per procedure 12 Fr). Early stent occlusion occurred in 73 (13 %) procedures. Female gender was protective against early stent occlusion (adjusted OR 0.54, 95 % CI 0.32-0.90, p = 0.02), while hilar stricture location was independently associated with a significantly increased risk of early stent occlusion (adjusted OR 3.41, 95 % CI 1.68-6.90, p = 0.0007). Early occlusion of conventional biliary stents occurred in 13 % of cases. While female gender decreased the risk of early stent occlusion, hilar stricture location was a significant predictor of early stent occlusion. Our results suggest that physicians should consider early elective stent exchange in patients with hilar strictures.

  10. 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. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  11. Prospective, multi-center evaluation of a silicon carbide coated cobalt chromium bare metal stent for percutaneous coronary interventions: Two-year results of the ENERGY Registry

    International Nuclear Information System (INIS)

    Erbel, Raimund; Eggebrecht, Holger; Roguin, Ariel; Schroeder, Erwin; Philipp, Sebastian; Heitzer, Thomas; Schwacke, Harald; Ayzenberg, Oded; Serra, Antonio; Delarche, Nicolas; Luchner, Andreas; Slagboom, Ton

    2014-01-01

    Background: Novel bare metal stents with improved stent design may become a viable alternative to drug-eluting stents in certain patient groups, particularly, when long-term dual antiplatelet therapy should be avoided. Purpose: The ENERGY registry aimed to assess the safety and benefits of a cobalt–chromium thin strut bare metal stent with a passive coating in a large series of patients under real-world conditions. Methods and materials: This prospective registry recruited 1016 patients with 1074 lesions in 48 centers from April to November 2010. The primary endpoint was the rate of major adverse cardiac events (MACEs), a composite of cardiac death, myocardial infarction and clinically driven target lesion revascularization. Results: More than half of the lesions (61.0%) were type A/B1 lesions, mean lesion length was 14.5 ± 6.5 mm and mean reference vessel diameter 3.2 ± 0.5 mm. MACE rates at 6, 12 and 24 months were 4.9%, 8.1% and 9.4%, target lesion revascularization rates 2.8%, 4.9% and 5.4% and definite stent thrombosis rates 0.5%, 0.6% and 0.6%. Subgroups showed significant differences in baseline and procedural characteristics which did not translate into significantly different clinical outcomes. Specifically, MACE rates at 24 months were 13.5% in diabetics, 8.6% in small stents and 9.6% in acute coronary syndrome patients. Conclusion: The population of ENERGY reflects real-world conditions with bare metal stents being mainly used in simple lesions. In this setting, percutaneous coronary intervention using a cobalt–chromium thin strut bare metal stent with a passive coating showed very good results up to 24 months. (ClinicalTrials.gov:NCT01056120) Summary for annotated table of contents: The ENERGY international registry evaluated the safety and benefits of a cobalt–chromium thin strut bare metal stent with passive coating in 1016 patients under real-world conditions until 2 years. Results were encouraging with a low composite rate of cardiac death

  12. Prospective, multi-center evaluation of a silicon carbide coated cobalt chromium bare metal stent for percutaneous coronary interventions: Two-year results of the ENERGY Registry

    Energy Technology Data Exchange (ETDEWEB)

    Erbel, Raimund, E-mail: erbel@uk-essen.de [Department of Cardiology, University of Duisburg-Essen, Essen (Germany); Eggebrecht, Holger [Cardioangiological Center Bethanien (CCB), Frankfurt (Germany); Roguin, Ariel [Department of Cardiology, Rambam Medical Center, Haifa (Israel); Schroeder, Erwin [Division of Cardiovascular Medicine, Cliniques Universitaires de Mont-Godinne, Yvoir (Belgium); Philipp, Sebastian [Department Internal Medicine/Cardiology, Elbe Klinikum Stade, Stade (Germany); Heitzer, Thomas [Department of Cardiology, Heart Center Dortmund, Dortmund (Germany); Schwacke, Harald [Department of Internal Medicine, Diakonissen-Stiftungs- Krankenhaus Speyer (Germany); Ayzenberg, Oded [The Heart Institute, Kaplan Medical Center, Rehovot (Israel); Serra, Antonio [Servicio de Cardiología, Hospital de la Santa Creu i Sant Pau, Barcelona, España (Spain); Delarche, Nicolas [Cardiology unit, Pau General Hospital, Pau (France); Luchner, Andreas [Department of Internal Medicine/Cardiology, Universitätsklinikum Regensburg (Germany); Slagboom, Ton [Department of Cardiology, Onze Lieve Vrouwe Gasthuis, Amsterdam (Netherlands)

    2014-11-15

    Background: Novel bare metal stents with improved stent design may become a viable alternative to drug-eluting stents in certain patient groups, particularly, when long-term dual antiplatelet therapy should be avoided. Purpose: The ENERGY registry aimed to assess the safety and benefits of a cobalt–chromium thin strut bare metal stent with a passive coating in a large series of patients under real-world conditions. Methods and materials: This prospective registry recruited 1016 patients with 1074 lesions in 48 centers from April to November 2010. The primary endpoint was the rate of major adverse cardiac events (MACEs), a composite of cardiac death, myocardial infarction and clinically driven target lesion revascularization. Results: More than half of the lesions (61.0%) were type A/B1 lesions, mean lesion length was 14.5 ± 6.5 mm and mean reference vessel diameter 3.2 ± 0.5 mm. MACE rates at 6, 12 and 24 months were 4.9%, 8.1% and 9.4%, target lesion revascularization rates 2.8%, 4.9% and 5.4% and definite stent thrombosis rates 0.5%, 0.6% and 0.6%. Subgroups showed significant differences in baseline and procedural characteristics which did not translate into significantly different clinical outcomes. Specifically, MACE rates at 24 months were 13.5% in diabetics, 8.6% in small stents and 9.6% in acute coronary syndrome patients. Conclusion: The population of ENERGY reflects real-world conditions with bare metal stents being mainly used in simple lesions. In this setting, percutaneous coronary intervention using a cobalt–chromium thin strut bare metal stent with a passive coating showed very good results up to 24 months. (ClinicalTrials.gov:NCT01056120) Summary for annotated table of contents: The ENERGY international registry evaluated the safety and benefits of a cobalt–chromium thin strut bare metal stent with passive coating in 1016 patients under real-world conditions until 2 years. Results were encouraging with a low composite rate of cardiac death

  13. Spectral Imaging for Intracranial Stents and Stent Lumen.

    Science.gov (United States)

    Weng, Chi-Lun; Tseng, Ying-Chi; Chen, David Yen-Ting; Chen, Chi-Jen; Hsu, Hui-Ling

    2016-01-01

    Application of computed tomography for monitoring intracranial stents is limited because of stent-related artifacts. Our purpose was to evaluate the effect of gemstone spectral imaging on the intracranial stent and stent lumen. In vitro, we scanned Enterprise stent phantom and a stent-cheese complex using the gemstone spectral imaging protocol. Follow-up gemstone spectral images of 15 consecutive patients with placement of Enterprise from January 2013 to September 2014 were also retrospectively reviewed. We used 70-keV, 140-keV, iodine (water), iodine (calcium), and iodine (hydroxyapatite) images to evaluate their effect on the intracranial stent and stent lumen. Two regions of interest were individually placed in stent lumen and adjacent brain tissue. Contrast-to-noise ratio was measured to determine image quality. The maximal diameter of stent markers was also measured to evaluate stent-related artifact. Two radiologists independently graded the visibility of the lumen at the maker location by using a 4-point scale. The mean of grading score, contrast/noise ratio and maximal diameter of stent markers were compared among all modes. All results were analyzed by SPSS version 20. In vitro, iodine (water) images decreased metallic artifact of stent makers to the greatest degree. The most areas of cheese were observed on iodine (water) images. In vivo, iodine (water) images had the smallest average diameter of stent markers (0.33 ± 0.17mm; P stent lumen (160.03 ±37.79; P stent-related artifacts of Enterprise and enhance contrast of in-stent lumen. Spectral imaging may be considered a noninvasive modality for following-up patients with in-stent stenosis.

  14. Percutaneous Ureteral stent insertion

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Yup; Sung, Dong Wook; Choi, Woo Suk; Lee, Dong Ho; Ko, Young Tae; Lee, Sun Wha; Lim, Jae Hoon [Kyung Hee University Hospital, Seoul (Korea, Republic of)

    1990-10-15

    Percutaneous ureteral stent insertion is a treatment of permanent or temporary urinary diversion to maintain continuity and function of the obstructed and injured ureter. We performed 31 cases of percutaneous double pig tall ureteral stent insertion in 21 patients, included 13 patients with malignant ureteral obstruction and eight patients with injured ureter as well as benign inflammatory stricture. Satisfactory resulted was obtained in all patients but one, who need percutaneous nephrostomy on week later for urinary diversion. No significant complication was encountered. The authors concluded that percutaneous ureteral stent insertion, an interventional procedure alternative to urologic retrograde method, is an effective method for urinary diversion.

  15. Comparison of the Absorbable Polymer Sirolimus-Eluting Stent (MiStent) to the Durable Polymer Everolimus-Eluting Stent (Xience) (from the DESSOLVE I/II and ISAR-TEST-4 Studies).

    Science.gov (United States)

    Lansky, Alexandra J; Kastrati, Adnan; Edelman, Elazer R; Parise, Helen; Ng, Vivian G; Ormiston, John; Wijns, William; Byrne, Robert A

    2016-02-15

    We compared the outcomes of a novel, thin-strut, cobalt-chromium, absorbable, polymer sirolimus-eluting stent (APSES; MiStent) to the durable polymer cobalt-chromium everolimus-eluting stent (EES; Xience). A propensity-matched analysis was performed comparing data from the DES With Sirolimus and a Bioabsorbable Polymer for the Treatment of Patients With De Novo Lesions in the Native Coronary Arteries (DESSOLVE) I and II studies, evaluating the APSES to the EES arm of the Intracoronary Stenting and Angiographic Results: Test Efficacy of 3 Limus-Eluting Stents-4 study. Target lesion failure (TLF) and its components were evaluated at 12 months and annually to 3 years; 805 patients (APSES = 153; EES = 652) were included with propensity matching in 204 patients (APSES = 102; EES = 102). APSES compared with EES had lower TLF at 1 year (3.0% vs 8.0%, p = 0.12) driven by a difference in target lesion revascularization (TLR; 1% vs 6%, p = 0.05), with no difference in target vessel myocardial infarction (p = 0.56) or stent thrombosis (p = 0.31). At 3 years, TLF (5.0% vs 12.5%, p = 0.07) and TLR (2.0% vs 8.4%, p = 0.04) remained lower with APSES. By landmark analysis, there was no significant difference in TLF between 1 and 3 years (p = 0.36). In conclusion, in a propensity-matched analysis, the APSES demonstrated reduced clinically indicated TLR rates at 1 and 3 years compared with the durable polymer EES, with minimal accrual of events between 1 and 3 years. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Asymptomatic strut fracture in DeBakey-Surgitool aortic valves: incidence, management, and metallurgic aspects.

    Science.gov (United States)

    Von Der Emde J, J; Eberlein, U; Breme J, J

    1990-01-01

    From August 1971 through November 1972, we implanted 62 Model 2 DeBakey-Surgitool aortic valve prostheses in 62 patients, 4 of whom later had clinically asymptomatic strut fractures. In 1 case, the patient died suddenly, and autopsy revealed detachment of the ball-cage; in each of the other 3 cases, fractures of 2 struts close to the base of the prosthesis were diagnosed fluoroscopically, and the patients underwent successful reoperation. The interval between implantation and reoperation ranged from 11 months to 16 years, 9 months. In 1 patient, retrospective study of chest radiographs revealed that the fracture had been present for 2(1/2) years. Larger valves (>/= A6) were affected significantly more often than smaller ones. We performed metallurgic analysis of 1 prosthesis: results revealed strut wear from fatigue cracking and secondary abrasion. Strut fracture was also promoted by suspension of the cage at right angles to the prosthetic ring and by use of a pyrolytic carbon ball in a titanium cage (i.e., an occluder harder than its holder). Patients with DeBakey-Surgitool aortic valve prostheses should undergo annual radiologic examinations to enable early detection of strut fractures. Prophylactic valve replacement is not indicated.

  17. Improvement and Application of the Softened Strut-and-Tie Model

    Science.gov (United States)

    Fan, Guoxi; Wang, Debin; Diao, Yuhong; Shang, Huaishuai; Tang, Xiaocheng; Sun, Hai

    2017-11-01

    Previous experimental researches indicate that reinforced concrete beam-column joints play an important role in the mechanical properties of moment resisting frame structures, so as to require proper design. The aims of this paper are to predict the joint carrying capacity and cracks development theoretically. Thus, a rational model needs to be developed. Based on the former considerations, the softened strut-and-tie model is selected to be introduced and analyzed. Four adjustments including modifications of the depth of the diagonal strut, the inclination angle of diagonal compression strut, the smeared stress of mild steel bars embedded in concrete, as well as the softening coefficient are made. After that, the carrying capacity of beam-column joint and cracks development are predicted using the improved softened strut-and-tie model. Based on the test results, it is not difficult to find that the improved softened strut-and-tie model can be used to predict the joint carrying capacity and cracks development with sufficient accuracy.

  18. 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

    2012-01-01

    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....

  19. Combined stent implantation and embolization with liquid 2-polyhydroxyethyl methacrylate for treatment of experimental canine wide-necked aneurysms

    Energy Technology Data Exchange (ETDEWEB)

    Klisch, J.; Zitt, J.; Schumacher, M. [Section of Neuroradiology, University of Freiburg (Germany); Schellhammer, F. [Department of Radiology, University of Cologne, Cologne (Germany); Scheufler, K.M. [Department of Neurosurgery, University of Freiburg (Germany); Pagenstecher, A. [Department of Neuropathology, University of Freiburg, Freiburg (Germany); Nagursky, H. [Department of Oral and Maxillofacial Surgery, University of Freiburg, Freiburg (Germany)

    2002-06-01

    The purpose of the study was the evaluation of 2-polyhydroxyethyl methacrylate (2-P-HEMA) for endovascular liquid embolization of experimental side-wall aneurysms following stent protection in a canine model. The swelling behaviour and polymerization characteristics of 2-P-HEMA in different solutions were investigated in vitro. Different methods for applications were tested in a latex aneurysm model under pulsatile flow conditions. Twenty broad-based carotid side-wall aneurysms were microsurgically produced in five dogs. Four weeks after surgery self-expandable nitinol stents were placed, covering the orifice of the aneurysms. 2-P-HEMA was injected via a microcatheter, which was positioned through the meshwork of the stent. Control angiography was performed immediately after treatment and after 1, 6 and 9 months. In-vivo stent placement succeeded in all but one case. Two aneurysms occluded spontaneously after stent placement. Combined embolization of 17 aneurysms using a stent and 2-P-HEMA was performed. Eleven aneurysms could be primarily completely occluded (65%). A small remaining neck was evident in six aneurysms. Efflux of 2-P-HEMA during the process of embolization was observed in seven aneurysms, due to an excess volume of 2-P-HEMA. The excessive 2-P-HEMA led to significant vessel stenosis in two cases. Two carotid arteries (three treated aneurysms) occluded after 1 month, due to insufficient anticoagulation management. Histological examination of embolized aneurysms revealed no foreign-body or inflammatory reaction. A smooth neo-intimal layer covered the stented vessel segment. Liquid embolization of side-wall aneurysms with 2-P-HEMA is technically feasible. Embolotherapy of aneurysms with liquid agents still has the risk that embolic material will exit even when it is stent-protected. To avoid this problem, stents with smaller strut diameter and/or additional balloon-protection are required. The inert 2-P-HEMA seems to be a promising agent for combining

  20. Percutaneous placement of ureteral stent

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Hyup; Park, Jae Hyung; Han, Joon Koo; Han, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1990-12-15

    Antegrade placement of ureteral stents has successfully achieved in 41 of 46 ureters. When it was difficult to advance ureteral stents through the lesion, it was facilitated by retrograde guide-wire snare technique through urethra. Complications associated with the procedure were non-function of ureteral stent by occlusion, upward migration,and spontaneous fracture of ureteral stent. These complications were managed by percutaneous nephrostomy and removal of ureteral stents by guide-wire snare technique and insertion of a new ureteral stent. While blood cell in urine was markedly increased in about 50% of patients following the procedure.

  1. A few insights into the nature of classical and quantum gravity via null-strut calculus

    International Nuclear Information System (INIS)

    Kheyfets, Arkady

    1989-01-01

    Null-strut calculus is a 3 + 1 formulation of standard Regge calculus, wherein the dynamics of 3-geometry is propagated in time along light rays, or 'null struts'. However, just as Regge calculus is a discrete and geometric tool for the description of Einstein's theory of gravitation, so too NSC offers itself as a discrete and geometric tool for the description of Einstein's spacetime as the dynamics of discrete spacelike 3-geometries in time, or discrete geometrodynamics. It has for its objectives to provide a discrete model of a 3 + 1 split of spacetime into space plus time, while in so doing to preserve and illuminate the geometric content of Einstein's theory of gravity. The feature of 'light-cone-produced duality' is central to null-strut calculus. This paper will capitalise on this feature, and will attempt to provide some insights into the nature of classical and quantum gravity. (Author)

  2. Drug eluting stents and modern stent technologies for in-stent restenosis.

    Science.gov (United States)

    Werner, Martin

    2017-08-01

    The implantation of metallic stents has become a standard procedure to improve the outcome after angioplasty of peripheral vessels. However, the occurrence of in-stent restenosis is hampering the long-term efficacy of these procedures and is associated with re-occurrence of symptoms. The optimal treatment modality for in-stent-restenosis in the peripheral vasculature is not well examined. This review discusses the existing evidence for the treatment of in-stent restenosis with drug eluting stents and modern stent technologies.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  4. 基于 Struts 框架的软件实训系统%Software Training System Based on Struts Architecture

    Institute of Scientific and Technical Information of China (English)

    龚雄兴; 宁彬; 袁磊

    2012-01-01

      基于Struts框架的软件实训系统主要是利用Web技术实现软件实训实践过程的网络化、信息化。文章分析了以 Struts 框架为技术基础的软件实训系统的设计与实现,改进了该系统应用及维护中的安全控制和中文请求响应设计,以更符合建设软件实训系统的现实需求。%  Software training system mainly uses Web technique to realize cyberization and informatization of teaching process on software training. Based on Struts architecture, it analyzes the design and realization of the software training system. Then safety control and response to Chinese language during the application are improved.

  5. Survival following fracture of strut from mitral prosthesis with disc translocation.

    Science.gov (United States)

    McEnany, M T; Wheeler, E O; Austen, W G

    1979-07-01

    Mechanical complications of prosthetic valves are increasingly rare. The acute, catastrophic nature of the symptoms associated with massive transvalvular regurgitation preclude survival except with immediate operation. In the patient described herein, two weld fractures of a Björk-Shiley mitral prosthetic strut led to displacement of the valve occluder into the left atrium. The patient survived reoperation, following which the strut was detected radiologically in the left ventricular free wall. A slow, limited recovery resulted from his 5 preoperative hours of deep shock and coma. No complication attributable to the retained ventricular foreign body has been identified.

  6. A fractured inferior vena cava filter strut migrating to the left pulmonary artery

    Directory of Open Access Journals (Sweden)

    Tamer Hudali

    2015-01-01

    Full Text Available Inferior vena cava filters are increasingly used in patients with recurrent venous thromboembolism who are contraindicated to anticoagulation. Migration of a broken strut to the pulmonary artery is a very rare complication of these filters. We report the case of an 83-year-old female who experienced this complication with the migratory strut remaining in the same position for years. This case provides evidence that such filters probably have higher rates of complications than what has been thought that remain asymptomatic. The indications and the management of complications of such devices need to be studied further.

  7. Future developments in biliary stenting

    Science.gov (United States)

    Hair, Clark D; Sejpal, Divyesh V

    2013-01-01

    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. PMID:23837001

  8. Renal PTA stenting

    International Nuclear Information System (INIS)

    Tsetis, D.

    2012-01-01

    Full text: Renal artery stenosis (RAS) is a common condition that may lead to hypertension, progressive renal dysfunction and cardiovascular morbidity. Catheter-based therapy for symptomatic, haemodynamically significant, RAS has become the preferred method of revascularization. Balloon angioplasty has been the traditional treatment of choice for fibromuscular dysplasia, however stents are increasingly used for the treatment of atheromatous lesions; in many cases-such as in ostial lesions-, direct stenting is strongly indicated. Despite the increased use of endovascular therapy for renal artery stenosis, there is still controversy regarding the optimal management and the net benefit of this treatment. Several randomized trials of balloon angioplasty or stenting for renal artery stenosis compared with medical therapy alone have been conducted, however these could not show definite advantage of endovascular therapy. Problems encountered with those trials include enrollment of small number of patients, frequent crossover from medical to interventional therapy compromising the intention-to-treat results, or selection of patients that are not expected to show clear benefit. The Angioplasty and Stenting for Renal Artery Lesions (ASTRAL) is the most important of these trials; however, it,s study design was faulty and therefore did not provide conclusive evidence to answer the question of whether angioplasty and stenting or medical therapy is the best treatment for haemodynamically significant RAS. All expectations are now focused on the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial which was designed to answer the same question, and its methodologies took into consideration the weaknesses of the ASTRAL trial. Regarding stent device itself, it seems that the optimal design is probably a stainless steel, laser cut, open-cells stent mounted on a rapid exchange delivery balloon catheter compatible with 0.014-in and 0.018-in guidewire. As a future

  9. Optical Coherence Tomography Substudy of A Prospective Multicenter Randomized Post-Market Trial to Assess the Safety and Effectiveness of the Firehawk™ Rapamycin Target Eluting Cobalt Chromium Coronary Stent System for the Treatment of Atherosclerotic Lesions: TARGET All Comers.

    Science.gov (United States)

    Baumbach, Andreas; Lansky, Alexandra J; Onuma, Yoshi; Asano, Taku; Johnson, Thomas; Anderson, Richard; Kiemeneij, Ferdinand; Zheng, Ming; Van Royen, Niels; Slagboom, Ton; Vlachojannis, Georg; Xu, Bo; Serruys, Patrick; Wijns, William

    2018-06-12

    Durable polymer drug-eluting stents (DP DES) may contribute to persistent inflammation, delayed endothelial healing and subsequent late DES thrombosis. The aim of this Optical Coherence Tomography (OCT) sub-study was to compare healing and neointimal coverage of a novel bioabsorbable polymer sirolimus-eluting stent (FIREHAWK®) (BP DES) versus the DP DES (XIENCE) at 90 days in an all comers patient population. The TARGET All Comers study is a prospective multicenter randomised post-market trial of 1656 patients randomised 1:1 to FIREHAWK or XIENCE at 21 centers in 10 European countries. The TARGET OCT sub-study enrolled 36 consecutive patients with 52 lesions at 6 centers proficient in OCT. Follow-up OCT was performed at 3 months or prior to revascularisation when occurring before the 3-month window. The substudy was designed for non-inferiority of the primary endpoint of neointimal thickness. At follow-up, the mean neointimal thickness by OCT (52 lesions, Firehawk, n=24; Xience, n=28), was not significantly different between groups (Firehawk 75.5μm vs Xience V 82.3 μm) meeting the primary endpoint of non-inferiority (Pnoninferiority<0.001). The percentage of stent strut coverage was high in both groups (strut level: 99.9% ± 0.3 vs 100% ± 0.1, p=0.26), and the proportion of malapposed struts (1.0±1.6% vs. 1.2±2.0%, p=0.51) was low in both groups. Based on OCT, the FIREHAWK BP DES has a similar healing response 3 months after implantation compared to the DP DES, with near complete strut coverage, moderate neointima formation and minimal strut malapposition.

  10. Excessive strut wear allowing ball-poppet embolization in a DeBakey-Surgitool aortic valve prosthesis.

    Science.gov (United States)

    Sutherland, R D; Guynes, W A; Nichols, C T; Martinez, H E

    1982-01-01

    Excessive cage strut wear allowing ball-poppet embolization caused the sudden death of a 47 year old lady in whom a DeBakey-Surgitool aortic prosthesis had been implanted nine years earlier. Patients with this type of prosthesis should have periodic valvular cine fluoroscopy with image intensification to allow visualization of significant strut wear or fracture, and appropriate prosthetic valve replacement.

  11. 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

  12. Heterogeneous Intravascular Ultrasound Findings of Stent Thrombosis

    OpenAIRE

    Morofuji, Toru; Inaba, Shinji; Aisu, Hiroe; Takahashi, Kayo; Saito, Makoto; Higashi, Haruhiko; Yoshii, Toyofumi; Sumimoto, Takumi

    2017-01-01

    Objective The underlying mechanisms of stent thrombosis are not completely understood. Methods We experienced 12 definite stent thrombosis cases (1 early, 1 late, and 10 very late) at our hospital from July 2011 to April 2016 and evaluated the possible causes of stent thrombosis by intravascular ultrasound (IVUS). Results Five different potential morphological causes of stent thrombosis (neoatherosclerosis, stent malapposition, stent fracture, edge dissection, and stent underexpansion) were d...

  13. An effective simplified model of composite compression struts for partially-restrained steel frame with reinforced concrete infill walls

    Science.gov (United States)

    Sun, Guohua; Chuang-Sheng, Walter Yang; Gu, Qiang; DesRoches, Reginald

    2018-04-01

    To resolve the issue regarding inaccurate prediction of the hysteretic behavior by micro-based numerical analysis for partially-restrained (PR) steel frames with solid reinforced concrete (RC) infill walls, an innovative simplified model of composite compression struts is proposed on the basis of experimental observation on the cracking distribution, load transferring mechanism, and failure modes of RC infill walls filled in PR steel frame. The proposed composite compression struts model for the solid RC infill walls is composed of α inclined struts and main diagonal struts. The α inclined struts are used to reflect the part of the lateral force resisted by shear connectors along the frame-wall interface, while the main diagonal struts are introduced to take into account the rest of the lateral force transferred along the diagonal direction due to the complicated interaction between the steel frame and RC infill walls. This study derives appropriate formulas for the effective widths of the α inclined strut and main diagonal strut, respectively. An example of PR steel frame with RC infill walls simulating simulated by the composite inclined compression struts model is illustrated. The maximum lateral strength and the hysteresis curve shape obtained from the proposed composite strut model are in good agreement with those from the test results, and the backbone curve of a PR steel frame with RC infill walls can be predicted precisely when the inter-story drift is within 1%. This simplified model can also predict the structural stiffness and the equivalent viscous damping ratio well when the inter-story drift ratio exceeds 0.5%.

  14. Valve-Like and Protruding Calcified Intimal Flap Complicating Common Iliac Arteries Kissing Stenting

    Directory of Open Access Journals (Sweden)

    George S. Georgiadis

    2015-01-01

    Full Text Available Endovascular therapy for iliac artery chronic total occlusions is nowadays associated with low rates of procedure-related complications and improved clinical outcomes, and it is predominantly used as first-line therapy prior to aortobifemoral bypass grafting. Herein, we describe the case of a patient presenting with an ischemic left foot digit ulcer and suffering complex aortoiliac lesions, who received common iliac arteries kissing stents, illustrating at final antegrade and retrograde angiograms the early recognition of a blood flow obstructing valve-like calcified intimal flap protruding through the stent struts, which was obstructing antegrade but not retrograde unilateral iliac arterial axis blood flow. The problem was resolved by reconstructing the aortic bifurcation at a more proximal level. Completion angiogram verified normal patency of aorta and iliac vessels. Additionally, a severe left femoral bifurcation stenosis was also corrected by endarterectomy-arterioplasty with a bovine patch. Postintervention ankle brachial pressure indices were significantly improved. At the 6-month and 2-year follow-up, normal peripheral pulses were still reported without intermittent claudication suggesting the durability of the procedure. Through stent-protruding calcified intimal flap, is a very rare, but existing source of antegrade blood flow obstruction after common iliac arteries kissing stents.

  15. Diagnostic accuracy of 64-slice multidetector CT for detection of in-stent restenosis in an unselected, consecutive patient population

    Energy Technology Data Exchange (ETDEWEB)

    Haraldsdottir, Sigurdis, E-mail: sigurdisha@gmail.com [Boston Medical Center, 72 East Concord Street (Evans 124), Boston, MA, 02118 (United States); Gudnason, Thorarinn, E-mail: thorgudn@landspitali.is [Landspitali University Hospital, Hringbraut, 101 Reykjavik (Iceland); Sigurdsson, Axel F., E-mail: axelfsig@landspitali.is [Landspitali University Hospital, Hringbraut, 101 Reykjavik (Iceland); Gudjonsdottir, Jonina, E-mail: jonina@rd.is [Rontgen Domus Medica, Egilsgata 3, 101 Reykjavik (Iceland); Lehman, Sam J., E-mail: slehman@partners.org [Massachusetts General Hospital, 165 Cambridge Street, Suite 400, Boston, MA 02114 (United States); Eyjolfsson, Kristjan, E-mail: kristey@landspitali.is [Landspitali University Hospital, Hringbraut, 101 Reykjavik (Iceland); Scheving, Sigurpall S., E-mail: sigurpal@landspitali.is [Landspitali University Hospital, Hringbraut, 101 Reykjavik (Iceland); Gibson, C. Michael, E-mail: mgibson@perfuse.org [Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02115 (United States); Hoffmann, Udo, E-mail: uhoffmann@partners.org [Massachusetts General Hospital, 165 Cambridge Street, Suite 400, Boston, MA 02114 (United States); Jonsdottir, Birna, E-mail: birna@rd.is [Rontgen Domus Medica, Egilsgata 3, 101 Reykjavik (Iceland); Andersen, Karl, E-mail: andersen@landspitali.is [Landspitali University Hospital, Hringbraut, 101 Reykjavik (Iceland)

    2010-11-15

    Objectives: To investigate the diagnostic accuracy of 64-slice multidetector computed tomography (64-CT) for detection of in-stent restenosis (ISR) in an unselected, consecutive patient population. Background: Detection of in-stent restenosis by cardiac CT would be a major advance for the evaluation of patients suspected of having ISR. However, the diagnostic accuracy of current generation 64-CT in this context is not fully established. Methods: We conducted a prospective study on patients with stable angina or acute coronary syndrome with no prior history of coronary artery disease. Six months after percutaneous coronary intervention (PCI) with stent placement they underwent a 64-CT scan (Toshiba Multi-Slice Aquilion 64) and consequently a repeat coronary angiography for comparison. Cardiac CT data sets were analyzed for the presence of in-stent restenosis by two independent expert readers blinded to the coronary angiographic data. Results: Ninety-three patients with a total of 140 stents were evaluated. Males comprised 82% of the study group and the mean age was 63 {+-} 10 years. The mean time from PCI to the repeat coronary angiography was 208 {+-} 37 days and the mean time from 64-CT to repeat coronary angiography was 3.7 {+-} 4.9 days. The restenosis rate according to coronary angiography was 26%. Stent diameter, strut thickness, heart rate and body mass index (BMI) significantly affected image quality. The sensitivity, specificity, positive and negative predictive values of 64-CT for detection of in-stent restenosis were 27%, 95%, 67% and 78%, respectively. Conclusions: Current generation, 64-slice CT, remains limited in its ability to accurately detect in-stent restenosis.

  16. 78 FR 73997 - Airworthiness Directives; Various Aircraft Equipped with Wing Lift Struts

    Science.gov (United States)

    2013-12-10

    ...-0023; Directorate Identifier 96-CE-072-AD; Amendment 39-17688; AD 99-01-05 R1] RIN 2120-AA64... Administration (FAA), DOT. ACTION: Final rule. SUMMARY: We are revising Airworthiness Directive (AD) 99-01-05 for certain aircraft equipped with wing lift struts. AD 99-01-05 required repetitively inspecting the wing...

  17. Design of squat shear walls using continuous strut-and-tie resistant models

    International Nuclear Information System (INIS)

    Santos, S.H. de C; Silva, R.E. da

    1993-01-01

    A new approach is presented for designing squat shear walls, subjected to seismic loading. In this approach, the strut-and-tie resistant models, proposed by Schlaich et al., are generalized in order to analyze continuous fields of compression and tension stresses. The application of the presented methodology is illustrated through numerical examples. (author)

  18. Vena Cava Filter Retrieval with Aorto-Iliac Arterial Strut Penetration.

    Science.gov (United States)

    Holly, Brian P; Gaba, Ron C; Lessne, Mark L; Lewandowski, Robert J; Ryu, Robert K; Desai, Kush R; Sing, Ronald F

    2018-05-03

    To evaluate the safety and technical success of inferior vena cava (IVC) filter retrieval in the setting of aorto-iliac arterial strut penetration. IVC filter registries from six large United States IVC filter retrieval practices were retrospectively reviewed to identify patients who underwent IVC filter retrieval in the setting of filter strut penetration into the adjacent aorta or iliac artery. Patient demographics, implant duration, indication for placement, IVC filter type, retrieval technique and technical success, adverse events, and post procedural clinical outcomes were identified. Arterial penetration was determined based on pre-procedure CT imaging in all cases. The IVC filter retrieval technique used was at the discretion of the operating physician. Seventeen patients from six US centers who underwent retrieval of an IVC filter with at least one strut penetrating either the aorta or iliac artery were identified. Retrieval technical success rate was 100% (17/17), without any major adverse events. Post-retrieval follow-up ranging from 10 days to 2 years (mean 4.6 months) was available in 12/17 (71%) patients; no delayed adverse events were encountered. Findings from this series suggest that chronically indwelling IVC filters with aorto-iliac arterial strut penetration may be safely retrieved.

  19. Self-oscillations of aircraft landing gear shock-strut at considerable non-linear friction

    Directory of Open Access Journals (Sweden)

    Б.М. Шифрин

    2004-01-01

    Full Text Available  The report considers self-oscillations at ε >1. The previous works were dedicated to the elastic frictional L.G. shock strut oscillations, the mathematical model of which is a non-linear differential equation with low ε parameter of its right-hand part.

  20. 78 FR 3356 - Airworthiness Directives; Various Aircraft Equipped With Wing Lift Struts

    Science.gov (United States)

    2013-01-16

    ...) of this AD, inspect the wing lift strut forks for cracks using magnetic particle procedures, such as... for Non-destructive Testing, or MIL-STD-410. (i) If no external corrosion is found on any wing lift..., the surface should be sanded or polished smooth before testing to assure a consistent and smooth...

  1. Euler Strut: A Mechanical Analogy for Dynamics in the Vicinity of a Critical Point

    Science.gov (United States)

    Bobnar, Jaka; Susman, Katarina; Parsegian, V. Adrian; Rand, Peter R.; Cepic, Mojca; Podgornik, Rudolf

    2011-01-01

    An anchored elastic filament (Euler strut) under an external point load applied to its free end is a simple model for a second-order phase transition. In the static case, a load greater than the critical load causes a Euler buckling instability, leading to a change in the filament's shape. The analysis of filament dynamics with an external point…

  2. Characterization of a hydro-pneumatic suspension strut with gas-oil emulsion

    Science.gov (United States)

    Yin, Yuming; Rakheja, Subhash; Yang, Jue; Boileau, Paul-Emile

    2018-06-01

    The nonlinear stiffness and damping properties of a simple and low-cost design of a hydro-pneumatic suspension (HPS) strut that permits entrapment of gas into the hydraulic oil are characterized experimentally and analytically. The formulation of gas-oil emulsion is studied in the laboratory, and the variations in the bulk modulus and mass density of the emulsion are formulated as a function of the gas volume fraction. An analytical model of the HPS is formulated considering polytropic change in the gas state, seal friction, and the gas-oil emulsion flows through orifices and valves. The model is formulated considering one and two bleed orifices configurations of the strut. The measured data acquired under a nearly constant temperature are used to identify gas volume fraction of the emulsion, and friction and flow discharge coefficients as functions of the strut velocity and fluid pressure. The results suggested that single orifice configuration, owing to high fluid pressure, causes greater gas entrapment within the oil and thus significantly higher compressibility of the gas-oil emulsion. The model results obtained under different excitations in the 0.1-8 Hz frequency range showed reasonably good agreements with the measured stiffness and damping properties of the HPS strut. The results show that the variations in fluid compressibility and free gas volume cause increase in effective stiffness but considerable reduction in the damping in a highly nonlinear manner. Increasing the gas volume fraction resulted in substantial hysteresis in the force-deflection and force-velocity characteristics of the strut.

  3. Anatomical variations and morphometric study of the optic strut and the anterior clinoid process

    Directory of Open Access Journals (Sweden)

    Eldan Kapur

    2012-05-01

    Full Text Available The optic strut and the anterior clinoid process represent bony structures that are closely related to anatomically and clinically significant elements such as the cavernous sinus, the internal carotid artery, the optic nerve and the pituitary gland. The objective of our study was to quantify dimensions of the optic strut and anterior clinoid process, and to determine variations in positions and forms of these structures. A descriptive anatomical study was performed on 200 dry human skulls. We analyzed dimensions and variations in position of the optic strut, dimensions of the anterior clinoid process as well as the incidence and forms of the caroticoclinoid foramen. The average thickness of the optic strut on skulls belonging to males was 3 mm and 2.8 mm on those belonging to females. The optic strut was most commonly attached to the anterior two fifths on the lower side of the anterior clinoid process. On the male skulls the average width of the anterior clinoid process was 9.4 mm (right and 9.1 mm (left. Its length was 9.9 and 9.3 mm. On female skulls the average width of the process was 8.7 mm (right and 8.3 mm (left, while the length measured 9.3 mm on the right and 8.9 mm on the opposite side. In our sample, a complete caroticoclinoid foramen appeared in 4.25%, a contact form in 2.75%. At last, an incomplete form of the foramen was observed in 9.75%. The anatomic variations of the investigated structures must be considered during the approaches to the cavernous sinus and neurovascular elements of the sellar region.

  4. A prospective, multicenter, post marketing surveillance study to evaluate the safety and effectiveness of the Superia-Sirolimus Eluting Coronary Stent System (SSECSS) implanted during routine clinical practice in India.

    Science.gov (United States)

    Chandra, Praveen; Kumar, Tarun

    2014-01-01

    A prospective, multicenter, post marketing surveillance study to evaluate the safety and effectiveness of the Superia-Sirolimus Eluting Coronary Stent System (SSECSS) implanted during routine clinical practice in India. 1. To study the MACE and in stent and In-segment Loss at Six Months (in a pre selected group of 50 patients). 1. Clinical and procedural success. This is a prospective, open label, single-arm, multicenter (16 sites), post marketing observational study enrolling patients implanted with Superia-Sirolimus Eluting Coronary Stent (SSECS) in routine clinical practice in India. A total of 200 Patients of coronary Artery Disease (CAD) implanted with Superia-Sirolimus Eluting Coronary Stent (SSECS) were enrolled. Clinical assessments were done at 30 days, 180 days and at 1, 2 years either telephonically or office visit. A cohort of 50 pre-selected patients were followed up for angiographic evaluation at 180 days. MACE at 12 month of follow up was 1.71%.Late lumen loss, in segment was 0.14 and in stent was 0.10 mm at 6 month of follow-up. TLR was required only in 2 patients. Superia stent is as safe as other biodegradable polymer stent in the market and time has come for biodegradable polymer stent with thin struts. Copyright © 2014 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

  5. 'Stent in a stent'--an alternative technique for removing partially covered stents following sleeve gastrectomy complications.

    Science.gov (United States)

    Vasilikostas, Georgios; Sanmugalingam, Nimalan; Khan, Omar; Reddy, Marcus; Groves, Chris; Wan, Andrew

    2014-03-01

    Endoscopic stenting is a relatively new technique for the treatment of post sleeve gastrectomy complications. Partially covered stents are used in this method to minimise the risk of migration but they are associated with difficulties with removal. Patients requiring emergency stenting following sleeve gastrectomy underwent insertion of a partially covered metallic stent. One month later, if the stent was not easily removable, a fully covered overlapping stent was inserted and the patient was readmitted 2 weeks later for removal of both stents. Four patients required stenting following sleeve gastrectomy leaks, and one patient required stenting for a stricture. In these cases, a 'stent in a stent' technique was used for removal. This technique allows the safe removal of partially covered stents inserted following sleeve gastrectomy complications.

  6. Angioplasty and stent placement - carotid artery

    Science.gov (United States)

    ... medlineplus.gov/ency/article/002953.htm Angioplasty and stent placement - carotid artery To use the sharing features ... to remove plaque buildup ( endarterectomy ) Carotid angioplasty with stent placement Description Carotid angioplasty and stenting (CAS) is ...

  7. The Effect of Stent Cell Geometry on Carotid Stenting Outcomes

    Energy Technology Data Exchange (ETDEWEB)

    Alparslan, Burcu, E-mail: burcu.alparslan@gmail.com [Yozgat State Hospital, Radiology Clinic (Turkey); Nas, Omer Fatih, E-mail: omerfatihnas@gmail.com [Uludag University Faculty of Medicine, Department of Radiology (Turkey); Eritmen, Ulku Turpcu, E-mail: drulkutur@hotmail.com.tr [Special Eregli Anatolia Hospital, Radiology Clinic (Turkey); Duran, Selcen, E-mail: selcenduran16@hotmail.com [Yerkoy State Hospital, Neurology Clinic (Turkey); Ozkaya, Guven, E-mail: ozkaya@uludag.edu.tr [Uludag University Faculty of Medicine, Department of Biostatistics (Turkey); Hakyemez, Bahattin, E-mail: bhakyemez@uludag.edu.tr [Uludag University Faculty of Medicine, Department of Radiology (Turkey)

    2016-04-15

    PurposeThe aim of this study was to investigate the effect of stent cell geometry on midterm results of carotid artery stenting (CAS).Materials and MethodOne hundred fifty-five patients underwent CAS between February 2010 and December 2012. Ninety-one open- and 84 closed-cell stents were used in this non-randomized, retrospective study. Periprocedural complications were defined as the ones happened during the procedure or within 30 days afterwards. Starting from the 6th month after the procedure, in-stent restenosis was detected with multidetector computed tomography angiography and classified into four groups from focal restenosis to occlusion.ResultsEleven complications were encountered in the periprocedural period (four on the open- and seven on the closed-cell group). Total complication rate was 6.3 % (11/175). No significant difference was detected in terms of periprocedural complications between two groups (p = 0.643). There was statistically significant difference between stent design groups in regard to radiological findings (p = 0.002). Sixteen of open-cell stents and three of closed-cell stents had focal restenosis. One closed-cell stent had diffuse proliferative restenosis and one open-cell stent had total occlusion.ConclusionIn-stent restenosis was more common in open-cell stent group, which have larger free cell area than closed-cell stents. Although our radiologic findings promote us to use closed-cell design if ‘possible’, no difference was detected in terms of clinical outcomes.

  8. Early experience with the multilayer aneurysm repair stent in the endovascular treatment of trans/infragenicular popliteal artery aneurysms: a mixed bag.

    Science.gov (United States)

    Thakar, Tejal; Chaudhuri, Arindam

    2013-06-01

    To present a preliminary experience using a multilayer flow-modulating stent for trans/infragenicular popliteal endovascular aneurysm repair. Five men (mean age 76 years, range 62-86) with 6 popliteal artery aneurysms (PAAs) measuring 22 to 39 mm in diameter (mean 30) underwent endovascular repair using the Cardiatis Multilayer Aneurysm Repair System (MARS) between June and August 2011. Radiological assessments post procedure using duplex ultrasonography and biplanar knee radiographs (additional contrast studies as necessary) sought evidence of aneurysm exclusion, graft patency, and preservation of branches and runoff vessels. Technical success was achieved in each case. There was one symptomatic stent occlusion requiring thrombectomy at 4 days, with reocclusion, and one leak via the stent struts into the sac with no branch outflow identified. Two further symptomatic stent occlusions were identified within a 6-week follow-up period, totaling 3 occlusions among the 6 devices deployed. No firm conclusion can be reached on the efficacy of the MARS in PAAs due to the inherent limitations of this small series, although a 50% thrombosis rate is a poor outcome. The risk of early thrombosis in flow-modulating stents deployed in the popliteal artery exists, as it does with earlier generation stent-grafts. Larger prospective trials and the influence of more aggressive antithrombotic/anticoagulant therapy should be considered to enable accurate evaluation of this device in popliteal artery aneurysms.

  9. Self-expandable metalic endotracheal stent

    International Nuclear Information System (INIS)

    Do, Young Soo; Cho, Dae Soon; Cho, Kyung Ja; Lee, Young Soo; Lee, Mi Jae

    1993-01-01

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

  10. Self-expandable metalic endotracheal stent

    Energy Technology Data Exchange (ETDEWEB)

    Do, Young Soo; Cho, Dae Soon; Cho, Kyung Ja; Lee, Young Soo; Lee, Mi Jae [Korea Cancer Center Hospital, Seoul (Korea, Republic of)

    1993-01-01

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

  11. The degradation and transport mechanism of a Mg-Nd-Zn-Zr stent in rabbit common carotid artery: A 20-month study.

    Science.gov (United States)

    Zhang, Jian; Li, Haiyan; Wang, Wu; Huang, Hua; Pei, Jia; Qu, Haiyun; Yuan, Guangyin; Li, Yongdong

    2018-03-15

    Mg-based stent is a promising candidate of the next generation fully degradable vascular stents. The latest progress includes the CE approval of the Magmaris ® WE43 based drug eluting stent. However, so far, the long term (more than 1 year implantation) in vivo degradation and the physiological effects caused by the degradation products were still unclear. In this study, a 20 month observation was carried out after the bare Mg-Nd-Zn-Zr (abbr. JDBM) stent prototype was implanted into the common carotid artery of New Zealand white rabbit in order to evaluate its safety, efficacy and especially degradation behavior. The degradation of the main second phase Mg 12 Nd was also studied. Results showed that the bare JDBM stent had good safety and efficacy with a complete re-endothelialization within 28 days. The JDBM stent struts were mostly replaced in situ by degradation products in 4 month. The important finding was that the volume and Ca concentration of the degradation products decreased in the long term, eliminating the clinicians' concern of possible vessel calcification. In addition, the alloying elements Mg and Zn in the stent could be safely metabolized as continuous enrichment in any of the main organs were not detected although Nd and Zr showed an abrupt increase in spleen and liver after 1 month implantation. Collectively, the long term in vivo results showed the rapid re-endothelialization of JDBM stent and the long term safety of the degradation products, indicating its great potential as the backbone of the fully degradable vascular stent. Mg-based stent is a promising candidate of the next generation fully degradable stents, especially after the recent market launch of one of its kind (Magmaris). However the fundamental question about the long term degradation and metabolic mechanism of Mg-based stent and its degradation products remain unanswered. We implanted our patented Mg-Nd-Zn-Zr bare stent into the common carotid artery of rabbits and

  12. A Zr-based bulk metallic glass for future stent applications: Materials properties, finite element modeling, and in vitro human vascular cell response.

    Science.gov (United States)

    Huang, Lu; Pu, Chao; Fisher, Richard K; Mountain, Deidra J H; Gao, Yanfei; Liaw, Peter K; Zhang, Wei; He, Wei

    2015-10-01

    Despite the prevalent use of crystalline alloys in current vascular stent technology, new biomaterials are being actively sought after to improve stent performance. In this study, we demonstrated the potential of a Zr-Al-Fe-Cu bulk metallic glass (BMG) to serve as a candidate stent material. The mechanical properties of the Zr-based BMG, determined under both static and cyclic loadings, were characterized by high strength, which would allow for the design of thinner stent struts to improve stent biocompatibility. Finite element analysis further complemented the experimental results and revealed that a stent made of the Zr-based BMG was more compliant with the beats of a blood vessel, compared with medical 316L stainless steel. The Zr-based BMG was found to be corrosion resistant in a simulated body environment, owing to the presence of a highly stable ZrO2-rich surface passive film. Application-specific biocompatibility studies were conducted using human aortic endothelial cells and smooth muscle cells. The Zr-Al-Fe-Cu BMG was found to support stronger adhesion and faster coverage of endothelial cells and slower growth of smooth muscle cells than 316L stainless steel. These results suggest that the Zr-based BMG could promote re-endothelialization and potentially lower the risk of restenosis, which are critical to improve vascular stent implantation integration. In general, findings in this study raised the curtain for the potential application of BMGs as future candidates for stent applications. Vascular stents are medical devices typically used to restore the lumen of narrowed or clogged blood vessel. Despite the clinical success of metallic materials in stent-assisted angioplasty, post-surgery complications persist due to the mechanical failures, corrosion, and in-stent restenosis of current stents. To overcome these hurdles, strategies including new designs and surface functionalization have been exercised. In addition, the development of new materials with

  13. 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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Numerical methods for polyline-to-point-cloud registration with applications to patient-specific stent reconstruction.

    Science.gov (United States)

    Lin, Claire Yilin; Veneziani, Alessandro; Ruthotto, Lars

    2018-03-01

    We present novel numerical methods for polyline-to-point-cloud registration and their application to patient-specific modeling of deployed coronary artery stents from image data. Patient-specific coronary stent reconstruction is an important challenge in computational hemodynamics and relevant to the design and improvement of the prostheses. It is an invaluable tool in large-scale clinical trials that computationally investigate the effect of new generations of stents on hemodynamics and eventually tissue remodeling. Given a point cloud of strut positions, which can be extracted from images, our stent reconstruction method aims at finding a geometrical transformation that aligns a model of the undeployed stent to the point cloud. Mathematically, we describe the undeployed stent as a polyline, which is a piecewise linear object defined by its vertices and edges. We formulate the nonlinear registration as an optimization problem whose objective function consists of a similarity measure, quantifying the distance between the polyline and the point cloud, and a regularization functional, penalizing undesired transformations. Using projections of points onto the polyline structure, we derive novel distance measures. Our formulation supports most commonly used transformation models including very flexible nonlinear deformations. We also propose 2 regularization approaches ensuring the smoothness of the estimated nonlinear transformation. We demonstrate the potential of our methods using an academic 2D example and a real-life 3D bioabsorbable stent reconstruction problem. Our results show that the registration problem can be solved to sufficient accuracy within seconds using only a few number of Gauss-Newton iterations. Copyright © 2017 John Wiley & Sons, Ltd.

  15. A prospective evaluation of the safety and efficacy of the TAXUS Element paclitaxel-eluting coronary stent system for the treatment of de novo coronary artery lesions: Design and statistical methods of the PERSEUS clinical program

    Directory of Open Access Journals (Sweden)

    Wehrenberg Scott

    2010-01-01

    Full Text Available Abstract Background Paclitaxel-eluting stents decrease angiographic and clinical restenosis following percutaneous coronary intervention compared to bare metal stents. TAXUS Element is a third-generation paclitaxel-eluting stent which incorporates a novel, thinner-strut, platinum-enriched metal alloy platform. The stent is intended to have enhanced radiopacity and improved deliverability compared to other paclitaxel-eluting stents. The safety and efficacy of the TAXUS Element stent are being evaluated in the pivotal PERSEUS clinical trials. Methods/Design The PERSEUS trials include two parallel studies of the TAXUS Element stent in single, de novo coronary atherosclerotic lesions. The PERSEUS Workhorse study is a prospective, randomized (3:1, single-blind, non-inferiority trial in subjects with lesion length ≤28 mm and vessel diameter ≥2.75 mm to ≤4.0 mm which compares TAXUS Element to the TAXUS Express2 paclitaxel-eluting stent system. The Workhorse study employs a novel Bayesian statistical approach that uses prior information to limit the number of study subjects exposed to the investigational device and thus provide a safer and more efficient analysis of the TAXUS Element stent. PERSEUS Small Vessel is a prospective, single-arm, superiority trial in subjects with lesion length ≤20 mm and vessel diameter ≥2.25 mm to Discussion The TAXUS PERSEUS clinical trial program uses a novel statistical approach to evaluate whether design and metal alloy iterations in the TAXUS Element stent platform provide comparable safety and improved procedural performance compared to the previous generation Express stent. PERSEUS trial enrollment is complete and primary endpoint data are expected in 2010. PERSEUS Workhorse and Small Vessel are registered at http://www.clinicaltrials.gov, identification numbers NCT00484315 and NCT00489541.

  16. Investigations on the Influence of the In-Stream Pylon and Strut on the Performance of a Scramjet Combustor

    Directory of Open Access Journals (Sweden)

    Hao Ouyang

    2014-01-01

    Full Text Available The influence of the in-stream pylon and strut on the performance of scramjet combustor was experimentally and numerically investigated. The experiments were conducted with a direct-connect supersonic model combustor equipped with multiple cavities. The entrance parameter of combustor corresponds to scramjet flight Mach number 4.0 with a total temperature of 947 K. The research results show that, compared with the scramjet combustor without pylon and strut, the wall pressure and the thrust of the scramjet increase due to the improvement of mixing and combustion effect due to the pylon and strut. The total pressure loss caused by the strut is considerable whereas pylon influence is slight.

  17. The Transport of Mass, Energy, and Entropy in Cryogenic Support Struts for Engineering Design

    Science.gov (United States)

    Elchert, J. P.

    2012-01-01

    Engineers working to understand and reduce cryogenic boil-off must solve a variety of transport problems. An important class of nonlinear problems involves the thermal and mechanical design of cryogenic struts. These classic problems are scattered about the literature and typically require too many resources to obtain. So, to save time for practicing engineers, the author presents this essay. Herein, a variety of new, old, and revisited analytical and finite difference solutions of the thermal problem are covered in this essay, along with commentary on approach and assumptions. This includes a few thermal radiation and conduction combined mode solutions with a discussion on insulation, optimum emissivity, and geometrical phenomenon. Solutions to cooling and heat interception problems are also presented, including a discussion of the entropy generation. The literature on the combined mechanical and thermal design of cryogenic support struts is reviewed with an introduction to the associated numerical methods.

  18. Bioresorbable scaffold -fourth revolution or failed revolution: Is low scaffold strut thickness the wrong target?

    Directory of Open Access Journals (Sweden)

    Sundeep Mishra

    2017-11-01

    Full Text Available Bioresorbable scaffold (BRS technology has currently fallen into disrepute because of inordinately high risk of scaffold thrombosis and post-procedure myocardial infarction. Low tensile and radial strengths of polymeric BRS contributing to improper strut embedment have been identified as major correlates of poor outcomes following BRS implantation. Magnesium has a better tensile/radial strength compared with polymeric BRS but it is still far lower than cobalt-chromium. Newers innovations utilizing alteration in polymer composition and orientation or even newer polymers have focused on attempts to reduce strut thickness but may have little effect on tensile/radial strength of finished product and therefore may not impact the BRS outcome on long run. Currently, newer generation BRS usage may be restricted to suitable low risk younger patients with proper vessel preparation and application of technique.

  19. Bioresorbable scaffold -fourth revolution or failed revolution: Is low scaffold strut thickness the wrong target?

    Science.gov (United States)

    Mishra, Sundeep

    Bioresorbable scaffold (BRS) technology has currently fallen into disrepute because of inordinately high risk of scaffold thrombosis and post-procedure myocardial infarction. Low tensile and radial strengths of polymeric BRS contributing to improper strut embedment have been identified as major correlates of poor outcomes following BRS implantation. Magnesium has a better tensile/radial strength compared with polymeric BRS but it is still far lower than cobalt-chromium. Newers innovations utilizing alteration in polymer composition and orientation or even newer polymers have focused on attempts to reduce strut thickness but may have little effect on tensile/radial strength of finished product and therefore may not impact the BRS outcome on long run. Currently, newer generation BRS usage may be restricted to suitable low risk younger patients with proper vessel preparation and application of technique. Copyright © 2017 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

  20. 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 ...

  1. Indications for stenting during thrombolysis

    DEFF Research Database (Denmark)

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

    2013-01-01

    of a stent in this position is the treatment of choice facilitating the venous flow into an unobstructed outflow tract either from the femoral vein or the deep femoral vein or both. The stent, made of stainless steel or nitinol, has to be self-expandable and flexible with radial force to overcome...... the challenges in this low-pressure system. The characteristics of the anatomy with external compression and often a curved vein segment with diameter difference make stent placement necessary. Ballooning alone has no place in this area. The proportion of inserted stents varies in the published materials...

  2. The effect of struts on the radiation diagram of Cassegrain antennas

    International Nuclear Information System (INIS)

    Henriques, L.M.D.

    1981-09-01

    This work presents a study on the effect of subreflector support members of Cassegrain antennas using the theory of scattering by cylinders structures. Expression for the surface current densities and arbitrary cross sections cylinders are developed, and the components for the scattered field are obtained. Using these results we analyse the effect of the struts on the gain reduction, and the rise of maximum side-lobe level. The final results obtained are then compared to other approximate theories. (author)

  3. The stenting strategy of drug-eluting stents for coronary artery disease in patients on dialysis

    Directory of Open Access Journals (Sweden)

    Hiroshi Fujita

    2014-12-01

    Full Text Available Background: Reports regarding the relationship between the length and diameter of implanted drug-eluting stents and clinical and angiographic outcomes in dialysis patients are limited. Aim: We investigated the efficiency of drug-eluting stents for coronary artery disease in patients on dialysis from the viewpoint of stent sizing. Methods: Sirolimus-eluting stents were implanted in 88 lesions and bare metal stents were implanted in 43 lesions. We compared stenting strategy, major adverse cardiac events, and angiographic results between sirolimus-eluting stent and bare metal stent groups. Results: Stent diameter was smaller and stent length was longer in the sirolimus-eluting stent group than in the bare metal stent group in our routine practices. There was no significant between-group difference in late diameter loss. Rates of angiographic restenosis and target lesion revascularization were significantly higher in the sirolimus-eluting stent group than in the bare metal stent group. Although stent length was significantly longer and stent diameter was smaller in the sirolimus-eluting stent group, sirolimus-eluting stents did not improve the subsequent clinical and angiographic results compared with bare metal stents in dialysis patients. Conclusion: In dialysis patients, a longer length and/or smaller diameter sirolimus-eluting stent implantation was associated with high rates of restenosis and target lesion revascularization compared with bare metal stents.

  4. Strut fracture of Björk-Shiley convexo-concave valve in Japan--risk of small valve size--.

    Science.gov (United States)

    Watarida, S; Shiraishi, S; Nishi, T; Imura, M; Yamamoto, Y; Hirokawa, R; Fujita, M

    2001-08-01

    The Björk-Shiley convexo-concave (BSCC) prosthetic valve was introduced in 1979. Between 1979 and 1986, approximately 86,000 BSCC valves were implanted. By December 31, 1994, 564 complete strut fractures had been reported to the manufacture. We experienced a case of an outlet strut fracture and investigated the risk of BSCC prosthetic valve fractures in Japan. To investigate the risk factor of a strut fracture in Japan, we investigated published cases of strut fractures. Between 1979 and 1986, 2021 BSCC valves were implanted in Japan. By January 31, 2000, 11 complete strut fractures of 60-degree BSCC valves including our case had occurred. The patients were eight males and three females. The average age at valve replacement was 42.4+/-8.1 years, and nine of eleven (81.8%) were patients valve fractured was 47.7+/-6.4 years, and eight of eleven (72.7%) were patients valve were 27 mm (n=5) (45.5%), 29 mm (n=3) (27.2%), and 31 mm (n=3) (27.2%). Four patients died and seven patients survived. Although only 11 BSCC valve struts fractured and statistical analysis could not be performed, our findings suggest that the high risk group for a strut fracture in Japan is young male patients with a mitral valve, >= 27 mm in size with BSCC models manufactured before March 1982. When following-up patients with BSCC models manufactured before March 1982, the possibility of a strut fracture in all BSCC valve sizes should be kept in mind.

  5. Dedicated bifurcation stents

    Directory of Open Access Journals (Sweden)

    Ajith Ananthakrishna Pillai

    2012-03-01

    Full Text Available Bifurcation percutaneous coronary intervention (PCI is still a difficult call for the interventionist despite advancements in the instrumentation, technical skill and the imaging modalities. With major cardiac events relate to the side-branch (SB compromise, the concept and practice of dedicated bifurcation stents seems exciting. Several designs of such dedicated stents are currently undergoing trials. This novel concept and pristine technology offers new hope notwithstanding the fact that we need to go a long way in widespread acceptance and practice of these gadgets. Some of these designs even though looks enterprising, the mere complex delivering technique and the demanding knowledge of the exact coronary anatomy makes their routine use challenging.

  6. Suggesting alternatives for reinforced concrete deep beams by reinforcing struts and ties

    Directory of Open Access Journals (Sweden)

    Saleem Abdul-Razzaq Khattab

    2017-01-01

    Full Text Available This paper studied reinforcing struts and ties in deep beams based on the Strut-and-Tie Model (STM of ACI 318M-14. The study contained testing 9 simply supported specimens, divided into 3 groups. The difference between the groups was the loading type which was 2-concentrated forces, 1-concentrated force and uniformly distributed load. Each group contained three specimens; the first specimens in each group were conventional deep beams as references which had a length of 1400 mm, a height of 400 mm and a width of 150 mm. The second specimens were the same as references in dimensions, but with removing shoulders. In addition, only the paths of struts & ties of STM were reinforced in the second specimens as compression and tension members, respectively. The third specimens were the frames that took their dimensions from STM of ACI 318M-14. From the experimental work, it is found that the proposed frames were good alternatives for the references despite the small loss in ultimate capacity. However, these proposed frames already carried loads greater than the factored design loads of STM. In comparison with the references, these proposed frames provided 41-51% reduction in weight, 4-27% reduction in cost besides providing front side area about 46-55%.

  7. Stent tunnel technique to save thrombosed native hemodialysis fistula with extensive venous aneurysm

    Directory of Open Access Journals (Sweden)

    Rabellino M

    2017-07-01

    Full Text Available Martin Rabellino,1 Guillermo J Rosa-Diez,2 Sergio A Shinzato,1 Pablo Rodriguez,1 Oscar A Peralta,1 Maria S Crucelegui,2 Rosario Luxardo,2 Agustina Heredia-Martinez,2 Mariela I Bedini-Rocca,2 Ricardo D García-Mónaco1 1Department of Angiography and Endovascular Therapy, 2Department of Nephrology, Hospital Italiano de Buenos Aires, Buenos Aires, Argentina Introduction and purpose: The increasing number of patients undergoing hemodialysis and the limited number of access sites have resulted in an increasing number of techniques to maintain vascular access for hemodialysis. Thrombosed arteriovenous (AV fistulas with large venous aneurysms have poor treatment results, with both endovascular and surgical techniques, leading to a high rate of definitive AV access loss. The purpose of this study was to review the feasibility and initial results of this novel endovascular treatment of thrombosed AV fistulas with large venous aneurysms.Materials and methods: A novel endovascular treatment technique of inserting nitinol auto-expandable uncovered stents stretching through the whole puncture site area, thus creating a tunnel inside the thrombus, was retrospectively analyzed and described.Results: A total of 17 stents were placed in 10 hemodialysis fistulas, with a mean venous coverage length of 17.8 cm. In all the cases, 100% technical success was achieved, with complete restoration of blood flow in all patients. There were no procedure-related complications. The mean follow-up was 167 days (range 60–420 days, with a primary and assisted patency of 80% and 100%, respectively. No multiple trans-stent struts-related complications were observed. Three stent fractures were diagnosed with plain films at the site of puncture without consequence in the venous access permeability.Conclusion: The “stent tunnel technique” is a feasible, safe and effective alternative to salvage native hemodialysis access, thus extending the function of the venous access with

  8. First-in-human evaluation of a bioabsorbable polymer-coated sirolimus-eluting stent: imaging and clinical results of the DESSOLVE I Trial (DES with sirolimus and a bioabsorbable polymer for the treatment of patients with de novo lesion in the native coronary arteries).

    Science.gov (United States)

    Ormiston, John; Webster, Mark; Stewart, James; Vrolix, Mathias; Whitbourn, Robert; Donohoe, Dennis; Knape, Charlene; Lansky, Alexandra; Attizzani, Guilherme F; Fitzgerald, Peter; Kandzari, David E; Wijns, William

    2013-10-01

    This first-in-human multicenter study sought to examine prospectively the safety and efficacy of a new, cobalt chromium thin-strut, coronary absorbable polymer-coated, sirolimus-eluting stent. Bioabsorbable polymers on drug-eluting stents may lower the long-term risks of inflammation, delayed healing, and adverse events. We enrolled patients with symptomatic coronary artery disease with stable or unstable angina pectoris and >50% diameter stenosis, amenable to coverage with a ≤23-mm long stent in a vessel 2.5 to 3.5 mm in diameter. All patients received dual antiplatelet therapy after implantation. Patients, in groups of 10, underwent repeat angiography, intravascular ultrasound, and optical coherence tomography at 4, 6, or 8 months, and all patients were seen or contacted at 18 months of follow-up. The median (range) in-stent late lumen loss (LLL) was 0.03 mm (-0.22 to 0.21 mm), 0.10 mm (-0.03 to 1.2 mm), and 0.08 mm (-0.01 to 0.28 mm), at 4, 6, and 8 months, respectively. At 18 months, the median in-stent LLL was 0.08 mm (-0.30 to 0.46 mm). On optical coherence tomography, the proportion of uncovered stent struts decreased from a median of 7.3% (range 0.4% to 46.3%) at 4 months to 0% (range: 0% to 3.4%) at 18 months. The percentage of neointimal volume obstruction by intravascular ultrasound increased from a median of 5.3% to 9.1% between 4 and 6 months and remained nearly unchanged thereafter through 18 months of follow-up. The only recorded major adverse cardiac event was a myocardial infarction. At 18 months of follow-up, this absorbable polymer-coated, cobalt chromium sirolimus-eluting stent was associated with a low and stable in-stent LLL, complete strut coverage, and no stent thrombosis. (First-In-Human Trial of the MiStent Drug-Eluting Stent [DES] in Coronary Artery Disease [DESSOLVE-I]; NCT01247428). Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  9. Randomized comparison of sirolimus eluting, and biolimus eluting bioresorbable polymer stents

    DEFF Research Database (Denmark)

    Andreasen, Lene N; Holm, Niels R; Balleby, Ida R

    2018-01-01

    -inferiority (Δ = 0.60 mm2) of the Orsiro DES to the Nobori DES for the primary endpoint of mean extra stent lumen (ESL) i.e. vessel lumen outside the stent at 13-month follow-up. We randomized 124 patients to Orsiro (n = 60) or Nobori (n = 64). Due to a difference in the one-sided 95%-confidence interval of 0.......26 mm2, but increased to 0.82 mm2 after appropriate log-transformation, it could not be rejected that Orsiro exceeded the non-inferiority limit. Testing for superiority, Orsiro had a significantly larger mean ESL at follow-up (Orsiro: 0.11 mm2 [0.02;0.30] mm2, Nobori: 0.03 mm2 [0.00;0.17] mm2, P = 0.......04). Stent strut coverage was, Orsiro: 97.6 % [93.8;99.4]%, and Nobori: 96.3 % [90.5;98,6]% (P = 0.13). Conclusion: Orsiro DES had a significantly larger mean ESL at follow-up and it could not be excluded that Orsiro exceeded the limit for non-inferiority. Nobori DES had a more heterogeneous distribution...

  10. Intravascular stent graft with polyurethane and metallic stent: experimental study

    International Nuclear Information System (INIS)

    Do, Young Soo; Lee, Won Jae; Kim, Boo Kyung Han; Park, Jae Hyung; Lee, Hak Jong; Lee, Sang Hyun; Kim, Sung Hyun; Kim, Jong Won; Ha, Jongwon

    1997-01-01

    To evaluate the usefulness of a new model of the stent graft, and of tissue response related to placement of the stent graft. The stent graft was constructed from polyurethane (Pellethane) graft and Hanaro stent(12mm in diameter, 45mm in length, 10 bends). A stent grafts was inserted into the lower thoracic aorta in each of six adult mongrel dogs(body weight, 12-16kg). At one, two, four, and six months, follow-up studies of angiography and spiral CT angiography were preformed to evaluate wascular patency, vascular stenosis, and thrombus formation. Two dogs were sacrificed at 1month, 2months, and 6months after insertion of the stent graft and macroscopic, light microscopic, and scanning electron microscopic examinations of the aortic segment including the stent graft were performed to evaluate intimal hyperplasia, endothelial growth to the graft, and thrombus formation. During follow-up at one, two, four, and six months, angiography or spiral CT angiography showed 20-100% luminal stenosis or occlusion of the lower thoracic aorta by the thrombus and perigraft leaks in three dogs(50%), and collateral vessels caused by occlusion of the aorta in two (33.3%). On gross examination, there were thrombi of 1-5mm thickness at the graft portions in all dogs, and this thickness gradually increased. The mean thickness of intimal hyperplasia at the stent portion gradually increased from 120μm to 227μm and the mean thickness of intimal hyperplasia at the graft portion from 93μm to 914μm. This thickness was greater at the graft portion than at the stent portion. Scanning electron microscopy showed elliptical endothelial lining on the neointimal surfaces at each end of the graft. Thrombi caused stenosis or occlusion of the stent graft. In order for such a graft to be ideal, further study is needed

  11. Stent fabric fatigue of grafts supported by Z-stents versus ringed stents: an in vitro buckling test.

    Science.gov (United States)

    Lin, Jing; Wang, Lu; Guidoin, Robert; Nutley, Mark; Song, Ge; Zhang, Ze; Du, Jia; Douville, Yvan

    2014-03-01

    Stent-grafts externally fitted with a Z-shaped stents were compared to devices fitted with ringed stents in an in vitro oscillating fatigue machine at 200 cycles per minute and a pressure of 360 mmHg for scheduled durations of up to 1 week. The devices fitted with Z-stents showed a considerably lower endurance limit to buckling compared to the controls. The contact between the apexes of adjacent Z-stents resulted in significant damage to the textile scaffolds and polyester fibers due to the sharp angle of the Z-stents. The ringed stents did not cause any fraying in the textile scaffolds.

  12. Percutaneous biliary drainage and stenting

    International Nuclear Information System (INIS)

    Totev, M.

    2012-01-01

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

  13. A Prospective, Multicenter Study of a Novel Mesh-Covered Carotid Stent: The CGuard CARENET Trial (Carotid Embolic Protection Using MicroNet).

    Science.gov (United States)

    Schofer, Joachim; Musiałek, Piotr; Bijuklic, Klaudija; Kolvenbach, Ralf; Trystula, Mariusz; Siudak, Zbigniew; Sievert, Horst

    2015-08-17

    This study sought to evaluate the feasibility of the CGuard Carotid Embolic Protective Stent system-a novel thin strut nitinol stent combined with a polyethylene terephthalate mesh covering designed to prevent embolic events from the target lesion in the treatment of carotid artery lesions in consecutive patients suitable for carotid artery stenting. The risk of cerebral embolization persists throughout the carotid artery stenting procedure and remains during the stent healing period. A total of 30 consecutive patients (age 71.6 ± 7.6 years, 63% male) meeting the conventional carotid artery stenting inclusion criteria were enrolled in 4 centers in Germany and Poland. The primary combined endpoint was the procedure success of the CGuard system and the number and volume of new lesions on the ipsilateral side assessed by diffusion-weighted magnetic resonance imaging at 48 h post-procedure and at 30 days. The secondary endpoint was 30-day major adverse cardiac or cerebrovascular events (death, stroke, or myocardial infarction). Protection devices were used in all procedures. Procedure success was 100%, with 0% procedural complications. The 30-day major adverse cardiac or cerebrovascular events rate was 0%. New ipsilateral ischemic lesions at 48 h occurred in 37.0% of patients and the average lesion volume was 0.039 ± 0.08 cm(3). The 30-day diffusion-weighted magnetic resonance imaging showed complete resolution of all but 1 periprocedural lesion and only 1 new minor (0.116 cm(3)) lesion in relation to the 48-h scan. The use of the CGuard system in patients undergoing carotid artery stenting is feasible. In addition, the benefit of using CGuard may extend throughout the stent healing period. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  14. Endotracheal expandable metallic stent placement in dogs

    Energy Technology Data Exchange (ETDEWEB)

    Sawada, S; Tanabe, Y; Fujiwara, Y; Koyama, T; Tanigawa, N; Kobayashi, M; Katsube, Y; Nakamura, H [Tottori Univ. School of Medicine, Yonago (Japan). Dept. of Radiology Research Inst. for Microbial Diseases, Osaka (Japan). Dept. of Radiology

    1991-01-01

    Various types of Gianturco zig-zag wire stent were implanted into the tracheas of 4 dogs to define the suitable characteristics of the endotracheal wire stent in these animals. These stents were constructed of 0.45, and 0.33 mm stainless steel wire. The diameter of the fully expanded stents was 3 cm and their lengths were 2, 3, and 4 cm. The 2 cm stent constructed of 0.33 mm wire showed minimum pathologic changes of the trachea of the dog compared to the other stents, and at the same time had a complete covering of ciliated columnar epithelium over the stent surface. (orig.).

  15. First-in-man randomised comparison of the BuMA Supreme biodegradable polymer sirolimus-eluting stent versus a durable polymer zotarolimus-eluting coronary stent: the PIONEER trial.

    Science.gov (United States)

    von Birgelen, Clemens; Asano, Taku; Amoroso, Giovanni; Aminian, Adel; Brugaletta, Salvatore; Vrolix, Mathias; Hernandez-Antolín, Rosana; van de Harst, Pim; Iñiguez, Andres; Janssens, Luc; Smits, Pieter C; Wykrzykowska, Joanna J; Ribeiro, Vasco Gama; Pereira, Hélder; da Silva, Pedro Canas; Piek, Jan J; Onuma, Yoshinobu; Serruys, Patrick W; Sabaté, Manel

    2018-04-20

    A second iteration of a sirolimus-eluting stent (SES) that has a biodegradable PLGA polymer coating with an electrografting base layer on a thin-strut (80 µm) cobalt-chromium platform (BuMA Supreme; SINOMED, Tianjin, China) has been developed. This first-in-man trial aimed to assess the efficacy and safety of the novel device. This randomised, multicentre, single-blinded, non-inferiority trial compared the BuMA Supreme SES versus a contemporary durable polymer zotarolimus-eluting stent (ZES) in terms of angiographic in-stent late lumen loss (LLL) at nine-month follow-up as the primary endpoint. A total of 170 patients were randomly allocated to treatment with either SES (n=83) or ZES (n=87). At nine-month angiographic follow-up, in-stent LLL was 0.29±0.33 mm in the SES group and 0.14±0.37 mm in the ZES group (pnon-inferiority=0.45). The in-stent percent diameter stenosis and the binary restenosis rate of the two treatment arms were similar (19.2±12.0% vs. 16.1±12.6%, p=0.09, and 3.3% vs. 4.4%, p=1.00, respectively). At 12-month clinical follow-up, there was no difference between treatment arms with regard to the device-oriented composite clinical endpoint (4.9% vs. 5.7%; p=0.72). The PIONEER trial did not meet its primary endpoint in terms of in-stent LLL at nine-month follow-up. However, this result did not translate into any increase in restenosis rate or impairment in 12-month clinical outcomes.

  16. Anterior debridement and fusion followed by posterior pedicle screw fixation in pyogenic spondylodiscitis: autologous iliac bone strut versus cage.

    Science.gov (United States)

    Pee, Yong Hun; Park, Jong Dae; Choi, Young-Geun; Lee, Sang-Ho

    2008-05-01

    An anterior approach for debridement and fusion with autologous bone graft has been recommended as the gold standard for surgical treatment of pyogenic spondylodiscitis. The use of anterior foreign body implants at the site of active infection is still a challenging procedure for spine surgeons. Several authors have recently introduced anterior grafting with titanium mesh cages instead of autologous bone strut in the treatment of spondylodiscitis. The authors present their experience of anterior fusion with 3 types of cages followed by posterior pedicle screw fixation. They also compare their results with the use of autologous iliac bone strut. The authors retrospectively reviewed the cases of 60 patients with pyogenic spondylodiscitis treated by anterior debridement between January 2003 and April 2005. Fusion using either cages or iliac bone struts was performed during the same course of anesthesia followed by posterior fixation. Twenty-three patients underwent fusion with autologous iliac bone strut, and 37 patients underwent fusion with 1 of the 3 types of cages. The infections resolved in all patients, as noted by normalization of their erythrocyte sedimentation rates and C-reactive protein levels. Patients in both groups were evaluated in terms of their preoperative and postoperative clinical and imaging findings. Single-stage anterior debridement and cage fusion followed by posterior pedicle screw fixation can be effective in the treatment of pyogenic spondylodiscitis. There was no difference in clinical and imaging outcomes between the strut group and cage group except for the subsidence rate. The subsidence rate was higher in the strut group than in the cage group. The duration until subsidence was also shorter in the strut group than in the cage group.

  17. Preliminary Report of Carotid Artery Stenting Using a Tapered Stent

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Chang Woo; Kim, Dong Hyun; Hong, Seung; Jeong; Kim, Young Suk; Byun, Joo Nam; Oh, Jae Hee [Dept. of Radiology, Chosun University College of Medicine, Gwangju (Korea, Republic of); Ahn, Seong Hwan [Dept. of Neurology, Chosun University College of Medicine, Gwangju (Korea, Republic of)

    2011-10-15

    To analyze the results of carotid artery stenting using a tapered stent and to evaluate the effectiveness of the tapered stent compared to previously reported studies using non-tapered stents. From October 2008 to August 2010, elective carotid artery stenting using a tapered stent was attempted in 39 lesions from 36 consecutive patients. Post-procedural complications were evaluated by neurologic symptoms and magnetic resonance imaging. Restenosis or occlusion was evaluated by carotid Doppler ultrasound and computerized tomography with angiography. Newly developed neurologic symptoms were evaluated clinically. The self-expandable tapered stent was placed across the carotid artery stenosis. A total stroke was noted in 3 patients, while a major stroke was noted in 1 patient. On diffusion weighted imaging, new lesions were observed in 15 patients, but 13 patients were clinically silent. Follow-up imaging studies were performed in the 13 clinically silent lesions, and no evidence of restenosis or occlusion was found any of the 13 lesions. During clinical follow-up in 34 lesions from 31 patients, there were newly developed neurological symptoms in only 1 patient.

  18. Radial force measurement of endovascular stents: Influence of stent design and diameter.

    Science.gov (United States)

    Matsumoto, Takuya; Matsubara, Yutaka; Aoyagi, Yukihiko; Matsuda, Daisuke; Okadome, Jun; Morisaki, Koichi; Inoue, Kentarou; Tanaka, Shinichi; Ohkusa, Tomoko; Maehara, Yoshihiko

    2016-04-01

    Angioplasty and endovascular stent placement is used in case to rescue the coverage of main branches to supply blood to brain from aortic arch in thoracic endovascular aortic repair. This study assessed mechanical properties, especially differences in radial force, of different endovascular and thoracic stents. We analyzed the radial force of three stent models (Epic, E-Luminexx and SMART) stents using radial force-tester method in single or overlapping conditions. We also analyzed radial force in three thoracic stents using Mylar film testing method: conformable Gore-TAG, Relay, and Valiant Thoracic Stent Graft. Overlapping SMART stents had greater radial force than overlapping Epic or Luminexx stents (P stents was greater than that of all three endovascular stents (P stents, site of deployment, and layer characteristics. In clinical settings, an understanding of the mechanical characteristics, including radial force, is important in choosing a stent for each patient. © The Author(s) 2015.

  19. Optical Coherence Tomography Guided Percutaneous Coronary Intervention With Nobori Stent Implantation in Patients With Non-ST-Segment-Elevation Myocardial Infarction (OCTACS) Trial

    DEFF Research Database (Denmark)

    Antonsen, Lisbeth; Thayssen, Per; Maehara, Akiko

    2015-01-01

    (s). A final OCT was performed in case of reintervention. Six-month OCT follow-up was available in 85 patients. Twenty-three (46%) OCT-guided patients had additional postdilation or stenting. The percentage of acutely malapposed struts was substantially lower in the OCT-guided group (3.4% [interquartile range......, 0.3-7.6] versus 7.8% [interquartile range, 2.3-19.4]; Pinterquartile range, 1.2-9.8] versus 9.0% [interquartile range, 5.5-14.5], P

  20. STRESS-DEFORMED STATE OF A STRUT-FRAMED CRANE GIRDER

    Directory of Open Access Journals (Sweden)

    Kh. M. Muselemov

    2017-01-01

    Full Text Available Objectives. The aim of the present work is to study the influence of design parameters on the stress-deformed state of a sprengel crane girder; to compile the tables and corresponding graphs illustrating changes in internal force factors in the characteristic cross-sections of the system elements under consideration. The article describes the study of the stress-deformed state (SDS of a metal strut-framed crane girder.Methods. Numerical methods of analysis based on the use of the Green's function are used during solving this problem. A dimensionless parameter is introduced, depending on which the tables and graphs are constructed. According to the known algorithm, the calculations of internal force factors in the sections of the considered construction are performed.Results. Depending on the dimensionless parameter characterising the geometry and physical features of the system, tables of bending moments and transverse forces are compiled. According to these tables, the appropriate graphs are plotted in order to choose easily the optimal design parameters.Conclusion. The dependence of the moments and transverse forces on the dimensionless parameter k was found, the corresponding graphs were plotted and the metal costs for the girders were calculated. The minimum values of the moments and transverse forces are established to take place when the dimensionless parameter k values are close to zero. The most economical was a strut-framed crane girder having k = 0.0001. The most uneconomical had k = 0.05 and k =∞. Eventually, the sprengel girders were found to be more profitable as compared to conventional crane girders. In the examples considered in the article, the metal savings amounted up to 14%. The presented methodology allows the calculation and designing of strut-framed crane girders with two racks to be carried out. 

  1. Meta-Analysis of Randomized Clinical Trials Comparing Biodegradable Polymer Drug-Eluting Stent to Second-Generation Durable Polymer Drug-Eluting Stents.

    Science.gov (United States)

    El-Hayek, Georges; Bangalore, Sripal; Casso Dominguez, Abel; Devireddy, Chandan; Jaber, Wissam; Kumar, Gautam; Mavromatis, Kreton; Tamis-Holland, Jacqueline; Samady, Habib

    2017-03-13

    The authors sought to perform a meta-analysis of randomized clinical trials (RCTs) comparing the safety and efficacy of biodegradable polymer drug-eluting stents (BP-DES) to second-generation durable polymer drug-eluting stents (DP-DES). Prior meta-analyses have established the superiority of BP-DES over bare-metal stents and first-generation DP-DES; however, their advantage compared with second-generation DP-DES remains controversial. The authors searched PubMed and Scopus databases for RCTs comparing BP-DES to the second-generation DP-DES. Outcomes included target vessel revascularization (TVR) as efficacy outcome and cardiac death, myocardial infarction (MI), and definite or probable stent thrombosis (ST) as safety outcomes. In addition, we performed landmark analysis for endpoints beyond 1 year of follow-up and a subgroup analysis based on the stent characteristics. The authors included 16 RCTs comprising 19,886 patients in the meta-analysis. At the longest available follow-up (mean duration 26 months), we observed no significant differences in TVR (p = 0.62), cardiac death (p = 0.46), MI (p = 0.98), or ST (risk ratio: 0.83, 95% confidence interval: 0.64 to 1.09; p = 0.19). Our landmark analysis showed that BP-DES were not associated with a reduction in the risk of very late ST (risk ratio: 0.87, 95% confidence interval: 0.49 to 1.53; p = 0.62). Similar outcomes were seen regardless of the eluting drug (biolimus vs. sirolimus), the stent platform (stainless steel vs. alloy), the kinetics of polymer degradation or drug release (6 months), the strut thickness of the BP-DES (thin 100 μm), or the DAPT duration (≥6 months vs. ≥12 months). BP-DES have similar safety and efficacy profiles to second-generation DP-DES. Published by Elsevier Inc.

  2. [Coronary stents: 30 years of medical progress].

    Science.gov (United States)

    Silvain, Johanne; Cayla, Guillaume; Collet, Jean-Philippe; Fargeot, Catherine; Montalescot, Gilles

    2014-03-01

    The history of interventional cardiology has been marked by several technologic revolutions since the late 1970s. The first key step was the use of inflatable balloon angioplasty as an alternative to CABG surgery for coronary revascularization, followed by intracoronary delivery of bare metal stent (BMS) and drug eluting stents (DES) to drastically reduce intracoronary restenosis observed with BMS. Improved stents platforms and polymers (absorbable or biocompatible) led to a dramatic reduction in the rate of late stent thrombosis. Self-expanding stents are now available to improve stent a position especially in acute myocardial infarction. The emergence of new fully bioabsorbable stents that can be combined with antiproliferative drugs is the ongoing revolution. A new generation of stents is continuously improving and likely to become the ideal stent for coronary revascularization in the near future. © 2014 médecine/sciences – Inserm.

  3. Experimental study on combustion modes and thrust performance of a staged-combustor of the scramjet with dual-strut

    Science.gov (United States)

    Yang, Qingchun; Chetehouna, Khaled; Gascoin, Nicolas; Bao, Wen

    2016-05-01

    To enable the scramjet operate in a wider flight Mach number, a staged-combustor with dual-strut is introduced to hold more heat release at low flight Mach conditions. The behavior of mode transition was examined using a direct-connect model scramjet experiment along with pressure measurements. The typical operating modes of the staged-combustor are analyzed. Fuel injection scheme has a significant effect on the combustor operating modes, particularly for the supersonic combustion mode. Thrust performances of the combustor with different combustion modes and fuel distributions are reported in this paper. The first-staged strut injection has a better engine performance in the operation of subsonic combustion mode. On the contrast, the second-staged strut injection has a better engine performance in the operation of supersonic combustion mode.

  4. Stenting of major airway constriction

    International Nuclear Information System (INIS)

    Wu Xiaomei

    2002-01-01

    Objective: To investigate the correlated issues in the stenting treatment of major airway constriction. Methods: Nineteen cases of major airway stenting procedure were studied retrospectively. The clinical choice of stents of different advantages or deficiencies were discussed. The importance of intravenous anesthesia supporting, life-parameters monitoring during the procedures and the prevention of complications were analysed. Results: Under intravenous and local anesthesia, 19 Wallstents had been successively placed and relieved 19 cases of major airway constrictions due to malignant or benign diseases (15 of tumors, 3 of tuberculosis, 1 of tracheomalacia). Intravenous anesthesia and life-parameters monitoring had made the procedures more safe and precise. Conclusions: Major airway stenting is an reliable method for relieving tracheobronchial stenosis; and intravenous anesthesia supporting and life-parameters monitoring guarantee the satisfactions of procedures

  5. [Minor strut fracture of the Björk-Shiley mitral valve].

    Science.gov (United States)

    Sugita, T; Yasuda, R; Watarida, S; Onoe, M; Tabata, R; Mori, A

    1990-06-01

    In May, 1982, a 49-year-old man underwent mitral valve replacement (MVR) in our hospital with a 31 mm Björk-Shiley prosthesis for mitral regurgitation. He had been doing well until his episode of palpitation and dyspnea of sudden onset, and was transferred to our ICU with severe cardiogenic shock in Aug, 1986. Chest X-ray film revealed pulmonary edema and breakage of the valve with migration of the disc and the minor strut of the prosthesis. He was operated upon 5 hours after the onset of his complaints. The minor strut was removed from the left upper pulmonary vein and mitral valve re-replacement was done with a 29 mm Björk-Shiley Monostrut valve. The disc which had dislocated into the abdominal aorta was also recovered on the twenty-third post operative day. His postoperative course was uneventful. Immediate diagnosis and subsequent re-operation is absolute indication for rescue from acute cardiac failure due to mechanical failure of any prosthetic valve.

  6. Strut and tie modeling for RC short beams with corroded stirrups

    Directory of Open Access Journals (Sweden)

    Ahmed K. El-Sayed

    Full Text Available Corrosion of steel reinforcement is one of the major problems that shorten the service life of reinforced concrete (RC structures. Steel stirrups, due to their location as an outer reinforcement, are more susceptible to corrosion problems and damage. However, there is limited research work in the literature on the effects of stirrup corrosion on the shear strength of RC beams. This paper attempts to evaluate analytically the residual shear strength of RC short beams with corrosion-damaged stirrups. The shear strength of short or deep beams are generally determined using the strut and tie model. The corrosion effects were implemented in the model to make it capable of predicting the residual shear capacity of RC beams with corroded stirrups. The effect of corrosion is implemented considering the reduction in geometry of the concrete cross section due to spalling and reduction in effective compressive strength of concrete due to corrosion cracks. The proposed strut and tie model which accounts for the corrosion effects was verified using the experimental data available in the literature, and good agreement was found.

  7. Ignition and Flame Stabilization of a Strut-Jet RBCC Combustor with Small Rocket Exhaust

    Directory of Open Access Journals (Sweden)

    Jichao Hu

    2014-01-01

    Full Text Available A Rocket Based Combined Cycle combustor model is tested at a ground direct connected rig to investigate the flame holding characteristics with a small rocket exhaust using liquid kerosene. The total temperature and the Mach number of the vitiated air flow, at exit of the nozzle are 1505 K and 2.6, respectively. The rocket base is embedded in a fuel injecting strut and mounted in the center of the combustor. The wall of the combustor is flush, without any reward step or cavity, so the strut-jet is used to make sure of the flame stabilization of the second combustion. Mass flow rate of the kerosene and oxygen injected into the rocket is set to be a small value, below 10% of the total fuel when the equivalence ratio of the second combustion is 1. The experiment has generated two different kinds of rocket exhaust: fuel rich and pure oxygen. Experiment result has shown that, with a relative small total mass flow rate of the rocket, the fuel rich rocket plume is not suitable for ignition and flame stabilization, while an oxygen plume condition is suitable. Then the paper conducts a series of experiments to investigate the combustion characteristics under this oxygen pilot method and found that the flame stabilization characteristics are different at different combustion modes.

  8. Hierarchical tailoring of strut architecture to control permeability of additive manufactured titanium implants

    International Nuclear Information System (INIS)

    Zhang, Z.; Jones, D.; Yue, S.; Lee, P.D.; Jones, J.R.; Sutcliffe, C.J.; Jones, E.

    2013-01-01

    Porous titanium implants are a common choice for bone augmentation. Implants for spinal fusion and repair of non-union fractures must encourage blood flow after implantation so that there is sufficient cell migration, nutrient and growth factor transport to stimulate bone ingrowth. Additive manufacturing techniques allow a large number of pore network designs. This study investigates how the design factors offered by selective laser melting technique can be used to alter the implant architecture on multiple length scales to control and even tailor the flow. Permeability is a convenient parameter that characterises flow, correlating to structure openness (interconnectivity and pore window size), tortuosity and hence flow shear rates. Using experimentally validated computational simulations, we demonstrate how additive manufacturing can be used to tailor implant properties by controlling surface roughness at a microstructual level (microns), and by altering the strut ordering and density at a mesoscopic level (millimetre). Highlights: • Experimentally validated permeability prediction tools for hierarchical implants. • Randomised structures form preferential flow channels with stronger shear flows. • Hierarchical strut structures allow independent tailoring of flow and pore size

  9. Hierarchical tailoring of strut architecture to control permeability of additive manufactured titanium implants

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z. [Department of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ (United Kingdom); Jones, D. [School of Engineering, University of Liverpool, Brownlow Hill, Liverpool, L69 3GH (United Kingdom); Yue, S. [Manchester X-ray Imaging Facility, School of Materials, The University of Manchester, Oxford Road, M13 9PL (United Kingdom); Lee, P.D., E-mail: peter.lee@manchester.ac.uk [Manchester X-ray Imaging Facility, School of Materials, The University of Manchester, Oxford Road, M13 9PL (United Kingdom); Jones, J.R. [Department of Materials, Imperial College London, South Kensington Campus, London, SW7 2AZ (United Kingdom); Sutcliffe, C.J. [School of Engineering, University of Liverpool, Brownlow Hill, Liverpool, L69 3GH (United Kingdom); Jones, E. [Department of Advanced Technology, Stryker Orthopaedics, Raheen Business Park, Limerick (Ireland)

    2013-10-15

    Porous titanium implants are a common choice for bone augmentation. Implants for spinal fusion and repair of non-union fractures must encourage blood flow after implantation so that there is sufficient cell migration, nutrient and growth factor transport to stimulate bone ingrowth. Additive manufacturing techniques allow a large number of pore network designs. This study investigates how the design factors offered by selective laser melting technique can be used to alter the implant architecture on multiple length scales to control and even tailor the flow. Permeability is a convenient parameter that characterises flow, correlating to structure openness (interconnectivity and pore window size), tortuosity and hence flow shear rates. Using experimentally validated computational simulations, we demonstrate how additive manufacturing can be used to tailor implant properties by controlling surface roughness at a microstructual level (microns), and by altering the strut ordering and density at a mesoscopic level (millimetre). Highlights: • Experimentally validated permeability prediction tools for hierarchical implants. • Randomised structures form preferential flow channels with stronger shear flows. • Hierarchical strut structures allow independent tailoring of flow and pore size.

  10. Three-Dimensional Printing of Hollow-Struts-Packed Bioceramic Scaffolds for Bone Regeneration.

    Science.gov (United States)

    Luo, Yongxiang; Zhai, Dong; Huan, Zhiguang; Zhu, Haibo; Xia, Lunguo; Chang, Jiang; Wu, Chengtie

    2015-11-04

    Three-dimensional printing technologies have shown distinct advantages to create porous scaffolds with designed macropores for application in bone tissue engineering. However, until now, 3D-printed bioceramic scaffolds only possessing a single type of macropore have been reported. Generally, those scaffolds with a single type of macropore have relatively low porosity and pore surfaces, limited delivery of oxygen and nutrition to surviving cells, and new bone tissue formation in the center of the scaffolds. Therefore, in this work, we present a useful and facile method for preparing hollow-struts-packed (HSP) bioceramic scaffolds with designed macropores and multioriented hollow channels via a modified coaxial 3D printing strategy. The prepared HSP scaffolds combined high porosity and surface area with impressive mechanical strength. The unique hollow-struts structures of bioceramic scaffolds significantly improved cell attachment and proliferation and further promoted formation of new bone tissue in the center of the scaffolds, indicating that HSP ceramic scaffolds can be used for regeneration of large bone defects. In addition, the strategy can be used to prepare other HSP ceramic scaffolds, indicating a universal application for tissue engineering, mechanical engineering, catalysis, and environmental materials.

  11. Determination of Strain Rate Sensitivity of Micro-struts Manufactured Using the Selective Laser Melting Method

    Science.gov (United States)

    Gümrük, Recep; Mines, R. A. W.; Karadeniz, Sami

    2018-03-01

    Micro-lattice structures manufactured using the selective laser melting (SLM) process provides the opportunity to realize optimal cellular materials for impact energy absorption. In this paper, strain rate-dependent material properties are measured for stainless steel 316L SLM micro-lattice struts in the strain rate range of 10-3 to 6000 s-1. At high strain rates, a novel version of the split Hopkinson Bar has been developed. Strain rate-dependent materials data have been used in Cowper-Symonds material model, and the scope and limit of this model in the context of SLM struts have been discussed. Strain rate material data and the Cowper-Symonds model have been applied to the finite element analysis of a micro-lattice block subjected to drop weight impact loading. The model output has been compared to experimental results, and it has been shown that the increase in crush stress due to impact loading is mainly the result of strain rate material behavior. Hence, a systematic methodology has been developed to investigate the impact energy absorption of a micro-lattice structure manufactured using additive layer manufacture (SLM). This methodology can be extended to other micro-lattice materials and configurations, and to other impact conditions.

  12. Biodegradable polymer sirolimus-eluting stents versus durable polymer everolimus-eluting stents for primary percutaneous coronary revascularisation of acute myocardial infarction.

    Science.gov (United States)

    Pilgrim, Thomas; Piccolo, Raffaele; Heg, Dik; Roffi, Marco; Tüller, David; Vuilliomenet, André; Muller, Olivier; Cook, Stéphane; Weilenmann, Daniel; Kaiser, Christoph; Jamshidi, Peiman; Khattab, Ahmed A; Taniwaki, Masanori; Rigamonti, Fabio; Nietlispach, Fabian; Blöchlinger, Stefan; Wenaweser, Peter; Jüni, Peter; Windecker, Stephan

    2016-12-10

    Our aim was to compare the safety and efficacy of a novel, ultrathin strut, biodegradable polymer sirolimus-eluting stent (BP-SES) with a thin strut, durable polymer everolimus-eluting stent (DP-EES) in a pre-specified subgroup of patients with acute ST-segment elevation myocardial infarction (STEMI) enrolled in the BIOSCIENCE trial. The BIOSCIENCE trial is an investigator-initiated, single-blind, multicentre, randomised non-inferiority trial (NCT01443104). Randomisation was stratified according to the presence or absence of STEMI. The primary endpoint, target lesion failure (TLF), is a composite of cardiac death, target vessel myocardial infarction, and clinically indicated target lesion revascularisation within 12 months. Between February 2012 and May 2013, 407 STEMI patients were randomly assigned to treatment with BP-SES or DP-EES. At one year, TLF occurred in seven (3.4%) patients treated with BP-SES and 17 (8.8%) patients treated with DP-EES (RR 0.38, 95% CI: 0.16-0.91, p=0.024). Rates of cardiac death were 1.5% in the BP-SES group and 4.7% in the DP-EES group (RR 0.31, 95% CI: 0.08-1.14, p=0.062); rates of target vessel myocardial infarction were 0.5% and 2.6% (RR 0.18, 95% CI: 0.02-1.57, p=0.082), respectively, and rates of clinically indicated target lesion revascularisation were 1.5% in the BP-SES group versus 2.1% in the DP-EES group (RR 0.69, 95% CI: 0.16-3.10, p=0.631). There was no difference in the risk of definite stent thrombosis. In this pre-specified subgroup analysis, BP-SES was associated with a lower rate of target lesion failure at one year compared to DP-EES in STEMI patients. These findings require confirmation in a dedicated STEMI trial.

  13. Stent migration after right ventricular outflow tract stenting in the severe cyanotic Tetralogy of Fallot case

    Directory of Open Access Journals (Sweden)

    Tamaki Hayashi

    2017-01-01

    Full Text Available We report our experience with a stent migration after right ventricle outflow tract stenting and converted to patent ductus arteriosus stenting in Tetralogy of Fallot (TOF with severe infundibular stenosis. Finally, the patient achieved to TOF repair, and the migrated stent was removed without any complication.

  14. The quantification of hemodynamic parameters downstream of a Gianturco Zenith stent wire using newtonian and non-newtonian analog fluids in a pulsatile flow environment.

    Science.gov (United States)

    Walker, Andrew M; Johnston, Clifton R; Rival, David E

    2012-11-01

    Although deployed in the vasculature to expand vessel diameter and improve blood flow, protruding stent struts can create complex flow environments associated with flow separation and oscillating shear gradients. Given the association between magnitude and direction of wall shear stress (WSS) and endothelial phenotype expression, accurate representation of stent-induced flow patterns is critical if we are to predict sites susceptible to intimal hyperplasia. Despite the number of stents approved for clinical use, quantification on the alteration of hemodynamic flow parameters associated with the Gianturco Z-stent is limited in the literature. In using experimental and computational models to quantify strut-induced flow, the majority of past work has assumed blood or representative analogs to behave as Newtonian fluids. However, recent studies have challenged the validity of this assumption. We present here the experimental quantification of flow through a Gianturco Z-stent wire in representative Newtonian and non-Newtonian blood analog environments using particle image velocimetry (PIV). Fluid analogs were circulated through a closed flow loop at physiologically appropriate flow rates whereupon PIV snapshots were acquired downstream of the wire housed in an acrylic tube with a diameter characteristic of the carotid artery. Hemodynamic parameters including WSS, oscillatory shear index (OSI), and Reynolds shear stresses (RSS) were measured. Our findings show that the introduction of the stent wire altered downstream hemodynamic parameters through a reduction in WSS and increases in OSI and RSS from nonstented flow. The Newtonian analog solution of glycerol and water underestimated WSS while increasing the spatial coverage of flow reversal and oscillatory shear compared to a non-Newtonian fluid of glycerol, water, and xanthan gum. Peak RSS were increased with the Newtonian fluid, although peak values were similar upon a doubling of flow rate. The introduction of the

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

    Directory of Open Access Journals (Sweden)

    Chang-Il Kwon

    2016-03-01

    Full Text Available 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.

  16. Angioplasty and stent placement - carotid artery - discharge

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000235.htm Angioplasty and stent placement - carotid artery - discharge To use the sharing ... the hospital. You may have also had a stent (a tiny wire mesh tube) placed in the ...

  17. Angioplasty and stent placement - peripheral arteries - discharge

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000234.htm Angioplasty and stent placement - peripheral arteries - discharge To use the sharing ... peripheral artery). You may have also had a stent placed. To perform the procedure: Your doctor inserted ...

  18. Angioplasty and stent placement - peripheral arteries

    Science.gov (United States)

    ... medlineplus.gov/ency/article/007393.htm Angioplasty and stent placement - peripheral arteries To use the sharing features ... inside the arteries and block blood flow. A stent is a small, metal mesh tube that keeps ...

  19. Management of stent dislodgment in coarctoplasty of aorta with three overlapping self-expandable nitinol stents.

    Science.gov (United States)

    Ghazi, Payam; Haji-Zeinali, Ali-Mohammad

    2010-01-01

    We describe a case of native coarctation of aorta managed with three self-expandable nitinol stents. After balloon pre-dilation, the first and second stents were dislodged. The coarcted area was successfully treated with the third stent overlapped with the previous stents. During follow up (30 months), the patient was free of complications. It seems that implantation of multiple overlapping self-expandable stents in aortic coarctation patients, if needed, is safe and possible.

  20. Compression and contact area of anterior strut grafts in spinal instrumentation: a biomechanical study.

    Science.gov (United States)

    Pizanis, Antonius; Holstein, Jörg H; Vossen, Felix; Burkhardt, Markus; Pohlemann, Tim

    2013-08-26

    Anterior bone grafts are used as struts to reconstruct the anterior column of the spine in kyphosis or following injury. An incomplete fusion can lead to later correction losses and compromise further healing. Despite the different stabilizing techniques that have evolved, from posterior or anterior fixating implants to combined anterior/posterior instrumentation, graft pseudarthrosis rates remain an important concern. Furthermore, the need for additional anterior implant fixation is still controversial. In this bench-top study, we focused on the graft-bone interface under various conditions, using two simulated spinal injury models and common surgical fixation techniques to investigate the effect of implant-mediated compression and contact on the anterior graft. Calf spines were stabilised with posterior internal fixators. The wooden blocks as substitutes for strut grafts were impacted using a "pressfit" technique and pressure-sensitive films placed at the interface between the vertebral bone and the graft to record the compression force and the contact area with various stabilization techniques. Compression was achieved either with posterior internal fixator alone or with an additional anterior implant. The importance of concomitant ligament damage was also considered using two simulated injury models: pure compression Magerl/AO fracture type A or rotation/translation fracture type C models. In type A injury models, 1 mm-oversized grafts for impaction grafting provided good compression and fair contact areas that were both markedly increased by the use of additional compressing anterior rods or by shortening the posterior fixator construct. Anterior instrumentation by itself had similar effects. For type C injuries, dramatic differences were observed between the techniques, as there was a net decrease in compression and an inadequate contact on the graft occurred in this model. Under these circumstances, both compression and the contact area on graft could only

  1. Effect of compressive force on aeroelastic stability of a strut-braced wing

    Science.gov (United States)

    Sulaeman, Erwin

    2002-01-01

    Recent investigations of a strut-braced wing (SBW) aircraft show that, at high positive load factors, a large tensile force in the strut leads to a considerable compressive axial force in the inner wing, resulting in a reduced bending stiffness and even buckling of the wing. Studying the influence of this compressive force on the structural response of SBW is thus of paramount importance in the early stage of SBW design. The purpose of the this research is to investigate the effect of compressive force on aeroelastic stability of the SBW using efficient structural finite element and aerodynamic lifting surface methods. A procedure is developed to generate wing stiffness distribution for detailed and simplified wing models and to include the compressive force effect in the SBW aeroelastic analysis. A sensitivity study is performed to generate response surface equations for the wing flutter speed as functions of several design variables. These aeroelastic procedures and response surface equations provide a valuable tool and trend data to study the unconventional nature of SBW. In order to estimate the effect of the compressive force, the inner part of the wing structure is modeled as a beam-column. A structural finite element method is developed based on an analytical stiffness matrix formulation of a non-uniform beam element with arbitrary polynomial variations in the cross section. By using this formulation, the number of elements to model the wing structure can be reduced without degrading the accuracy. The unsteady aerodynamic prediction is based on a discrete element lifting surface method. The present formulation improves the accuracy of existing lifting surface methods by implementing a more rigorous treatment on the aerodynamic kernel integration. The singularity of the kernel function is isolated by implementing an exact expansion series to solve an incomplete cylindrical function problem. A hybrid doublet lattice/doublet point scheme is devised to reduce

  2. Metglas-Elgiloy bi-layer, stent cell resonators for wireless monitoring of viscosity and mass loading

    KAUST Repository

    Viswanath, Anupam

    2012-12-21

    This paper presents the design and evaluation of magnetoelastic sensors intended for wireless monitoring of tissue accumulation in peripheral artery stents. The sensors are fabricated from 28 μm thick foils of magnetoelastic 2826MB Metglas™, an amorphous Ni-Fe alloy. The sensor layer consists of a frame and an active resonator portion. The frame consists of 150 μm wide struts that are patterned in the same wishbone array pattern as a 12 mm × 1.46 mm Elgiloy stent cell. The active portion is a 10 mm long symmetric leaf shape and is anchored to the frame at mid length. The active portion nests within the stent cell, with a uniform gap separating the two. A gold-indium eutectic bonding process is used to bond Metglas™ and Elgiloy foils, which are subsequently patterned to form bi-layer resonators. The response of the sensor to viscosity changes and mass loading that precede and accompany artery occlusion is tested in vitro. The typical sensitivity to viscosity of the fundamental, longitudinal resonant frequency at 361 kHz is 427 ppm cP -1 over a 1.1-8.6 cP range. The sensitivity to mass loading is typically between 63000 and 65000 ppm mg-1 with the resonant frequency showing a reduction of 8.1% for an applied mass that is 15% of the unloaded mass of the sensor. This is in good agreement with the theoretical response. © 2013 IOP Publishing Ltd.

  3. Metglas-Elgiloy bi-layer, stent cell resonators for wireless monitoring of viscosity and mass loading

    KAUST Repository

    Viswanath, Anupam; Green, Scott Ryan; Kosel, Jü rgen; Gianchandani, Yogesh B.

    2012-01-01

    This paper presents the design and evaluation of magnetoelastic sensors intended for wireless monitoring of tissue accumulation in peripheral artery stents. The sensors are fabricated from 28 μm thick foils of magnetoelastic 2826MB Metglas™, an amorphous Ni-Fe alloy. The sensor layer consists of a frame and an active resonator portion. The frame consists of 150 μm wide struts that are patterned in the same wishbone array pattern as a 12 mm × 1.46 mm Elgiloy stent cell. The active portion is a 10 mm long symmetric leaf shape and is anchored to the frame at mid length. The active portion nests within the stent cell, with a uniform gap separating the two. A gold-indium eutectic bonding process is used to bond Metglas™ and Elgiloy foils, which are subsequently patterned to form bi-layer resonators. The response of the sensor to viscosity changes and mass loading that precede and accompany artery occlusion is tested in vitro. The typical sensitivity to viscosity of the fundamental, longitudinal resonant frequency at 361 kHz is 427 ppm cP -1 over a 1.1-8.6 cP range. The sensitivity to mass loading is typically between 63000 and 65000 ppm mg-1 with the resonant frequency showing a reduction of 8.1% for an applied mass that is 15% of the unloaded mass of the sensor. This is in good agreement with the theoretical response. © 2013 IOP Publishing Ltd.

  4. Plastic biliary stents for malignant biliary diseases

    NARCIS (Netherlands)

    Huibregtse, Inge; Fockens, Paul

    2011-01-01

    Plastic biliary endoprostheses have not changed much since their introduction more than 3 decades ago. Although their use has been challenged by the introduction of metal stents, plastic stents still remain commonly used. Much work has been done to improve the problem of stent obstruction but

  5. Therapies targeting inflammation after stent implantation.

    Science.gov (United States)

    Okura, Hiroyuki; Takagi, Tsutomu; Yoshida, Kiyoshi

    2013-07-01

    Since the introduction of coronary vessel scaffold by metallic stent, percutaneous coronary intervention has become widely performed all over the world. Although drug-eluting stent technology has further decrease the incidence of in-stent restenosis, there still remaining issues related to stent implantation. Vessel inflammation is one of the causes that may be related to stent restenosis as well as stent thrombosis. Therefore, systemic therapies targeting inflammation emerged as adjunctive pharmacological intervention to improve outcome. Statins, corticosteroids, antiplatelets, and immunosuppresive or anti-cancer drugs are reported to favorably impact outcome after bare-metal stent implantation. In type 2 diabetic patients, pioglitazone may be the most promising drug that can lower neointimal proliferation and, as a result, lower incidence of restenosis and target lesion revascularization. On the other hand, several new stent platforms that might decrease inflammatory response after drug-eluting stent implantation have been introduced. Because durable polymer used in the first generation drug-eluting stents are recognized to be responsible for unfavorable vessel response, biocompatible or bioabsorbable polymer has been introduce and already used clinically. Furthermore, polymer-free drug-eluting stent and bioresorbable scaffold are under investigation. Although vessel inflammation may be reduced by using these new drug-eluting stents or scaffold, long-term impact needs to be investigated further.

  6. Incidence and predictors of coronary stent thrombosis

    DEFF Research Database (Denmark)

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

    2013-01-01

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

  7. 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 stent...

  8. 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 to...

  9. Metallic ureteral stents in malignant ureteral obstruction: clinical factors predicting stent failure.

    Science.gov (United States)

    Chow, Po-Ming; Hsu, Jui-Shan; Huang, Chao-Yuan; Wang, Shuo-Meng; Lee, Yuan-Ju; Huang, Kuo-How; Yu, Hong-Jheng; Pu, Yeong-Shiau; Liang, Po-Chin

    2014-06-01

    To provide clinical outcomes of the Resonance metallic ureteral stent in patients with malignant ureteral obstruction, as well as clinical factors predicting stent failure. Cancer patients who have received Resonance stents from July 2009 to March 2012 for ureteral obstruction were included for chart review. Stent failure was detected by clinical symptoms, image studies, and renal function tests. Survival analysis for stent duration was used to estimate patency rate and factors predicting stent failure. A total of 117 stents were inserted successfully into 94 ureteral units in 79 patients. There were no major complications. These stents underwent survival analysis and proportional hazard regression. The median duration for the stents was 5.77 months. In multivariate analysis, age (P=0.043), preoperative serum creatinine level (P=0.0174), and cancer type (P=0.0494) were significant factors associated with stent failure. Cancer treatment before and after stent insertion had no effect on stent duration. Resonance stents are effective and safe in relieving malignant ureteral obstructions. Old age and high serum creatinine level are predictors for stent failure. Stents in patients with lower gastrointestinal cancers have longer functional duration.

  10. Bi-directional evolutionary structural optimization for strut-and-tie modelling of three-dimensional structural concrete

    Science.gov (United States)

    Shobeiri, Vahid; Ahmadi-Nedushan, Behrouz

    2017-12-01

    This article presents a method for the automatic generation of optimal strut-and-tie models in reinforced concrete structures using a bi-directional evolutionary structural optimization method. The methodology presented is developed for compliance minimization relying on the Abaqus finite element software package. The proposed approach deals with the generation of truss-like designs in a three-dimensional environment, addressing the design of corbels and joints as well as bridge piers and pile caps. Several three-dimensional examples are provided to show the capabilities of the proposed framework in finding optimal strut-and-tie models in reinforced concrete structures and verifying its efficiency to cope with torsional actions. Several issues relating to the use of the topology optimization for strut-and-tie modelling of structural concrete, such as chequerboard patterns, mesh-dependency and multiple load cases, are studied. In the last example, a design procedure for detailing and dimensioning of the strut-and-tie models is given according to the American Concrete Institute (ACI) 318-08 provisions.

  11. Experimental investigation on combustion performance of cavity-strut injection of supercritical kerosene in supersonic model combustor

    Science.gov (United States)

    Sun, Ming-bo; Zhong, Zhan; Liang, Jian-han; Wang, Hong-bo

    2016-10-01

    Supersonic combustion with cavity-strut injection of supercritical kerosene in a model scramjet engine was experimentally investigated in Mach 2.92 facility with the stagnation temperatures of approximately 1430 K. Static pressure distribution in the axial direction was determined using pressure transducers installed along the centerline of the model combustor top walls. High speed imaging camera was used to capture flame luminosity and combustion region distribution. Multi-cavities were used to and stabilize the combustion in the supersonic combustor. Intrusive injection by thin struts was used to enhance the fuel-air mixing. Supercritical kerosene at temperatures of approximately 780 K and various pressures was prepared using a heat exchanger driven by the hot gas from a pre-burner and injected at equivalence ratios of approximately 1.0. In the experiments, combustor performances with different strut injection schemes were investigated and compared to direct wall injection scheme based on the measured static pressure distributions, the specific thrust increments and the images obtained by high-speed imaging camera. The experimental results showed that the injection by thin struts could obtain an enhanced mixing in the field but could not acquire a steady flame when mixing field cannot well match cavity separation region. There is no significant difference on performance between different schemes since the unsteady intermittent and oscillating flame leads to no actual combustion efficiency improvement.

  12. Hierarchical tailoring of strut architecture to control permeability of additive manufactured titanium implants.

    Science.gov (United States)

    Zhang, Z; Jones, D; Yue, S; Lee, P D; Jones, J R; Sutcliffe, C J; Jones, E

    2013-10-01

    Porous titanium implants are a common choice for bone augmentation. Implants for spinal fusion and repair of non-union fractures must encourage blood flow after implantation so that there is sufficient cell migration, nutrient and growth factor transport to stimulate bone ingrowth. Additive manufacturing techniques allow a large number of pore network designs. This study investigates how the design factors offered by selective laser melting technique can be used to alter the implant architecture on multiple length scales to control and even tailor the flow. Permeability is a convenient parameter that characterises flow, correlating to structure openness (interconnectivity and pore window size), tortuosity and hence flow shear rates. Using experimentally validated computational simulations, we demonstrate how additive manufacturing can be used to tailor implant properties by controlling surface roughness at a microstructual level (microns), and by altering the strut ordering and density at a mesoscopic level (millimetre). Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Nonlinear mode interaction in equal-leg angle struts susceptible to cellular buckling.

    Science.gov (United States)

    Bai, L; Wang, F; Wadee, M A; Yang, J

    2017-11-01

    A variational model that describes the interactive buckling of a thin-walled equal-leg angle strut under pure axial compression is presented. A formulation combining the Rayleigh-Ritz method and continuous displacement functions is used to derive a system of differential and integral equilibrium equations for the structural component. Solving the equations using numerical continuation reveals progressive cellular buckling (or snaking) arising from the nonlinear interaction between the weak-axis flexural buckling mode and the strong-axis flexural-torsional buckling mode for the first time-the resulting behaviour being highly unstable. Physical experiments conducted on 10 cold-formed steel specimens are presented and the results show good agreement with the variational model.

  14. Coronary and peripheral stenting in aorto-ostial protruding stents: The balloon assisted access to protruding stent technique.

    Science.gov (United States)

    Helmy, Tarek A; Sanchez, Carlos E; Bailey, Steven R

    2016-03-01

    Treatment of aorto-ostial in-stent restenosis lesions represents a challenge for interventional cardiologists. Excessive protrusion of the stent into the aorta may lead to multiple technical problems, such as difficult catheter reengagement of the vessel ostium or inability to re-wire through the stent lumen in repeat interventions. We describe a balloon assisted access to protruding stent technique in cases where conventional coaxial engagement of an aorto-ostial protruding stent with the guide catheter or passage of the guide wire through the true lumen is not feasible. This technique is applicable both in coronary and peripheral arteries. © 2015 Wiley Periodicals, Inc.

  15. Free fibular strut graft in neglected femoral neck fractures in adult

    Directory of Open Access Journals (Sweden)

    Azam Md Quamar

    2009-01-01

    Full Text Available Background: Neglected femoral neck fracture in adults still poses a formidable challenge. Existing treatment options varies from osteotomy (with or without graft to osteosynthesis using various implants and grafting techniques (muscle pedicle, vascularized, and nonvascularized fibula. The aim of this study was to assess outcome of nonvascularized fibular strut graft and cancellous screw fixation in neglected femoral neck fractures in the younger age group. Materials and Methods: Medical records of 32 patients of neglected femoral neck fracture, in the age group of 22-45 years (mean 37.8 years, operated between May 1994 to December 2001, were retrospectively reviewed. After the application of inclusion and exclusion criteria, 28 patients having three years minimum follow-up (mean 4.6 years were included. Delay between injury and operation varied from four weeks to 42 weeks (mean 16.4 weeks. Closed reduction was achieved in 17 patients; open reduction through Watson-Jones anterolateral approach was performed in the remaining 15 patients in whom closed reduction failed. The fracture was transfixed with three parallel guide wires. Appropriate sized cannulated lag screw (7 mm was then inserted in two of the wires. Selection of the third guide wire for fibula depended on the space available in both anteroposterior and lateral view. Results: Satisfactory bony union was obtained in 25 patients, of whom in four cases, the union occurred in 10-20° (mean 15° of varus. Nonunion occurred in three patients (9.37%, and aseptic necrosis occurred in another six patients (18.75%. Of the 25 patients where union was achieved, five patients showed excellent results; 14 good and six had poor functional result, as evaluated using modified Anglen criteria. Conclusion: Nonvascularized fibular strut graft along with cancellous screws provides a dependable and technically less-demanding alternative procedure for neglected femoral neck fractures in young adults. Fibula

  16. Experimental absorbable stent permits airway remodeling.

    Science.gov (United States)

    Liu, Kuo-Sheng; Liu, Yun-Hen; Peng, Yi-Jie; Liu, Shih-Jung

    2011-02-01

    Despite metallic and silicone stents being effective in treating various airway lesions, many concerns still remain. A bioresorbable stent that scaffolds the airway lumen and dissolves after the remodeling process is completed has advantages over metallic and silicone stents. We designed and fabricated a new mesh-type bioresorbable stent with a backbone of polycaprolactone (PCL), and evaluated its safety and biocompatibility in a rabbit trachea model. The PCL stent was fabricated by a laboratory-made microinjection molding machine. In vitro mechanical strength of the PCL stents was tested and compared to that of commercial silicone stents. The bioresorbable stents were surgically implanted into the cervical trachea of New Zealand white rabbits (n=6). Animals received bronchoscopic examination at 1, 2, 4, 8, and 12 weeks after surgery. Histological examination was completed to evaluate the biocompatibility of the stents. No animals died during the period of study. Distal stent migration was noted in 1 rabbit. In-stent secretion accumulation was found in 2 rabbits. Histological examination showed intact ciliated epithelium and marked leukocyte infiltration in the submucosa of the stented area at 10 and 28 weeks. Stent degradation was minimal, and the mechanical strength was well preserved at the end of 33 weeks. These preliminary findings showed good safety and biocompatibility of the new PCL stent when used in the airway remodeling. PCL could be a promising bioresorbable material for stent design if prolonged degradation time is required. Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  17. Long-term efficacy and safety of biodegradable-polymer biolimus-eluting stents: main results of the Basel Stent Kosten-Effektivitäts Trial-PROspective Validation Examination II (BASKET-PROVE II), a randomized, controlled noninferiority 2-year outcome trial.

    Science.gov (United States)

    Kaiser, Christoph; Galatius, Soeren; Jeger, Raban; Gilgen, Nicole; Skov Jensen, Jan; Naber, Christoph; Alber, Hannes; Wanitschek, Maria; Eberli, Franz; Kurz, David J; Pedrazzini, Giovanni; Moccetti, Tiziano; Rickli, Hans; Weilenmann, Daniel; Vuillomenet, André; Steiner, Martin; Von Felten, Stefanie; Vogt, Deborah R; Wadt Hansen, Kim; Rickenbacher, Peter; Conen, David; Müller, Christian; Buser, Peter; Hoffmann, Andreas; Pfisterer, Matthias

    2015-01-06

    Biodegradable-polymer drug-eluting stents (BP-DES) were developed to be as effective as second-generation durable-polymer drug-eluting stents (DP-DES) and as safe >1 year as bare-metal stents (BMS). Thus, very late stent thrombosis (VLST) attributable to durable polymers should no longer appear. To address these early and late aspects, 2291 patients presenting with acute or stable coronary disease needing stents ≥3.0 mm in diameter between April 2010 and May 2012 were randomly assigned to biolimus-A9-eluting BP-DES, second-generation everolimus-eluting DP-DES, or thin-strut silicon-carbide-coated BMS in 8 European centers. All patients were treated with aspirin and risk-adjusted doses of prasugrel. The primary end point was combined cardiac death, myocardial infarction, and clinically indicated target-vessel revascularization within 2 years. The combined secondary safety end point was a composite of VLST, myocardial infarction, and cardiac death. The cumulative incidence of the primary end point was 7.6% with BP-DES, 6.8% with DP-DES, and 12.7% with BMS. By intention-to-treat BP-DES were noninferior (predefined margin, 3.80%) compared with DP-DES (absolute risk difference, 0.78%; -1.93% to 3.50%; P for noninferiority 0.042; per protocol P=0.09) and superior to BMS (absolute risk difference, -5.16; -8.32 to -2.01; P=0.0011). The 3 stent groups did not differ in the combined safety end point, with no decrease in events >1 year, particularly VLST with BP-DES. In large vessel stenting, BP-DES appeared barely noninferior compared with DP-DES and more effective than thin-strut BMS, but without evidence for better safety nor lower VLST rates >1 year. Findings challenge the concept that durable polymers are key in VLST formation. http://www.clinicaltrials.gov. Unique identifier: NCT01166685. © 2014 American Heart Association, Inc.

  18. Microvascular stent anastomosis using N-fibroin stents: feasibility, ischemia time, and complications.

    Science.gov (United States)

    Smeets, Ralf; Vorwig, Oliver; Wöltje, Michael; Gaudin, Robert; Luebke, Andreas M; Beck-Broichsitter, Benedicta; Rheinnecker, Michael; Heiland, Max; Grupp, Katharina; Gröbe, Alexander; Hanken, Henning

    2016-05-01

    To evaluate a novel microvascular anastomosis technique using N-fibroin stents. Cylinder stents of 1 mm diameter and 5 mm length were fabricated using N-fibroin from silkworms. In 22 rats, aortas were dissected, and the stent was inserted into the two ends of the aorta and fixed using methylmethacrylate. Stent anastomosis was successful in 21 (96%) rats. The mean ischemia time was 7.4 minutes, significantly shorter than the 15.9 minutes in the control group with conventional sutures (P stent anastomosis cases, and marked host rejection was evident at the stent anastomosis sites. Around the stents, thrombi were frequent (52%). Our study demonstrated the basic feasibility of stent anastomosis using N-fibroin stents and reduced ischemia time. However, thrombus formation, frequent and severe abdominal infections, and heavy host rejection remain critical issues. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Endoscopic stent suture fixation for prevention of esophageal stent migration during prolonged dilatation for achalasia treatment.

    Science.gov (United States)

    Rieder, E; Asari, R; Paireder, M; Lenglinger, J; Schoppmann, S F

    2017-04-01

    The aim of this study is to compare endoscopic stent suture fixation with endoscopic clip attachment or the use of partially covered stents (PCS) regarding their capability to prevent stent migration during prolonged dilatation in achalasia. Large-diameter self-expanding metal stents (30 mm × 80 mm) were placed across the gastroesophageal junction in 11 patients with achalasia. Stent removal was scheduled after 4 to 7 days. To prevent stent dislocation, endoscopic clip attachment, endoscopic stent suture fixation, or PCS were used. The Eckardt score was evaluated before and 6 months after prolonged dilatation. After endoscopic stent suture fixation, no (0/4) sutured stent migrated. When endoscopic clips were used, 80% (4/5) clipped stents migrated (p = 0.02). Of two PCS (n = 2), one migrated and one became embedded leading to difficult stent removal. Technical adverse events were not seen in endoscopic stent suture fixation but were significantly correlated with the use of clips or PCS (r = 0.828, p = 0.02). Overall, 72% of patients were in remission regarding their achalasia symptoms 6 months after prolonged dilatation. Endoscopic suture fixation of esophageal stents but not clip attachment appears to be the best method of preventing early migration of esophageal stents placed at difficult locations such as at the naive gastroesophageal junction. © The Authors 2017. Published by Oxford University Press on behalf of International Society for Diseases of the Esophagus. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  20. Angulated Stents-A Novel Stent Improvisation to Manage Difficult Post-tuberculosis Bronchial Stenosis.

    Science.gov (United States)

    Tay, Chee Kiang; Jeong, Byeong-Ho; Kim, Hojoong

    2017-10-18

    Post-tuberculosis bronchostenosis (PTBS), a complication of endobronchial tuberculosis is currently treated by bronchial stenting. However, in cases of angulated bronchial stenoses, difficulty is often encountered in stent insertion and maintenance, resulting in stent migration, granulation tissue overgrowth, and restenosis. To accommodate the angulated alignment of the stenosis, we devised an "angulated stent"-a novel improvisation of the conventional stent via splicing and suturing to achieve a resultant angulated shape. A retrospective review was undertaken to evaluate the performance of this stent. Among 283 PTBS patients who underwent interventional bronchoscopy at our center from 2004 to 2014, 21 were treated with at least one angulated stent. Clinical outcomes, including the stenting duration were investigated. After a median follow-up of 26 months, stent removal was successful in 7 (33.3%) out of 21 patients. In patients managed with angulated stents, the median duration to stent change or eventual removal was longer than those treated with straight tube stents (392 days vs. 86 days; p < 0.05). Angulated stents are a feasible treatment option in patients with angulated PTBS by reducing complications and prolonging the stent-changing interval.

  1. Primary and revision efficacy of cross-wired metallic stents for endoscopic bilateral stent-in-stent placement in malignant hilar biliary strictures.

    Science.gov (United States)

    Lee, T H; Moon, J H; Kim, J H; Park, D H; Lee, S S; Choi, H J; Cho, Y D; Park, S H; Kim, S J

    2013-01-01

    Endoscopic bilateral drainage for inoperable malignant hilar biliary strictures (HBS) using metal stents is considered to be technically difficult. Furthermore, endoscopic revision of bilateral stenting after occlusion can be challenging. This study was performed to evaluate the long-term efficacy of endoscopic bilateral stent-in-stent placement of cross-wired metallic stents in high-grade malignant HBS and planned endoscopic bilateral revision. A total of 84 patients with inoperable high-grade malignant HBS were enrolled from three academic tertiary referral centers. Two cross-wired metal stents were inserted using a bilateral stent-in-stent placement method. Bilateral endoscopic revision was also performed during follow-up using either identical metal stents or plastic stents. The main outcome measurements were technical and functional success, complications, stent patency, and endoscopic revision efficacy. The technical and clinical success rates of endoscopic bilateral stent-in-stent placement of cross-wired metallic stents were 95.2% (80/84) and 92.9% (78/84), respectively. Median patency (range) and survival were 238 days (10-429) and 256 days (10-1130), respectively. Obstruction of primary bilateral stents occurred in 30.8% (24/78) of patients with functionally successful stent placement. The technical and clinical success rates of planned bilateral endoscopic revision for occluded stents were 83.3% (20/24) and 79.2% (19/24), respectively. For revision, bilateral metallic stents were placed in 11 patients (55.0%); the remaining patients received plastic stents. Palliative endoscopic bilateral stent-in-stent placement of cross-wired metallic stents was effective in patients with inoperable HBS. Revision endoscopic bilateral stenting may be feasible and successful in cases where the primary deployed metal stents are occluded. © Georg Thieme Verlag KG Stuttgart · New York.

  2. Endobronchial Occlusion Stent: A Preliminary Experimental Study

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yo Won; Jeong, Woo Kyoung; Lee, Seoung Hoon; Heo, Jeong Nam; Jeon, Seok Chol [Hanyang University College of Medicine, Seoul (Korea, Republic of); Ko, Gi Young; Song, Ho Young [University of Ulsan College of Medicine, Ulsan (Korea, Republic of)

    2010-04-15

    To evaluate the safety and the technical feasibility of the use of an endobronchial occlusion stent and to get preliminary data for the development of the optimal material required for endobronchial occlusions. A commercialized, self-expandable tracheobronchial stent was modified; one half had a polyurethane cover with an occluded end and the other half was uncovered with a flaring configuration. The occluded end was placed such that it would face the distal lung. Under fluoroscopic guidance, seven stents were placed at the lower lobar bronchus in 6 mini-pigs. The bronchial obstruction was examined immediately after stent placement. Chest radiographs were taken at days 1, 7, 14, and 28 after stent placement and the removed airways from two, two, one, and one mini-pigs sacrificed on corresponding days were examined for the maintenance of bronchial obstruction. Stents were successfully placed and induced the immediate bronchial obstruction in all mini-pigs. Five of seven airways with occlusion stents maintained an obstruction until the mini-pigs were sacrificed. Proximal stent migration occurred in two mini-pigs (29%), and pulmonary consolidations were observed distal to four of the stents (57%). The placement of an endobronchial occlusion stent and the obstruction of targeted bronchi seem to be feasible, but an add-on check valve should be considered to prevent stent migration and obstructive pneumonia

  3. Outlet strut fracture of Björk-Shiley convexo-concave valves: can valve-manufacturing characteristics explain the risk?

    Science.gov (United States)

    Omar, R Z; Morton, L S; Beirne, M; Blot, W J; Lawford, P V; Hose, R; Taylor, K M

    2001-06-01

    Björk-Shiley 60 degrees convexo-concave prosthetic heart valves (Shiley, Inc, Irvine, Calif, a subsidiary of Pfizer, Inc) continue to be a concern for approximately 35,000 nonexplanted patients worldwide, with approximately 600 events reported to the manufacturer to date. Fractures of the outlet struts of the valves began to appear in the early 1980s and have continued to the present, but their causes are only partially understood. A matched case-control study was conducted evaluating manufacturing records for 52 valves with outlet strut fractures and 248 control subjects matched for age at implantation, valve size, and valve position. In addition to the risk factors recognized as determinants of outlet strut fracture, the United Kingdom case-control study has observed 7- to 9-fold increased risk with performance of multiple hook deflection tests. This test was performed more than once, usually after rework on the valve. Six valves in this study underwent multiple hook deflection tests, of which 4 experienced an outlet strut fracture. Cracks and further rework were noted for these valves. Significant associations were also observed between outlet strut fracture and disc-to-strut gap measurements taken before the attachment of the sewing ring. It is our view that a combination of factors related to valve design, manufacturing process, and patient characteristics are responsible for outlet strut fractures of Björk-Shiley convexo-concave valves. Multiple hook deflection tests have emerged as a potential new risk factor for outlet strut fracture in both The Netherlands and the United Kingdom. This factor appears to be correlated with the presence of other abnormalities. A further study is needed to investigate the factors correlated with multiple hook deflection tests. On confirmation of risk, the presence of multiple hook deflection tests may be added to equations, quantifying the risk of outlet strut fracture for comparison against risk of mortality and serious

  4. A comparative evaluation of early stent occlusion among biliary conventional versus wing stents.

    Science.gov (United States)

    Khashab, Mouen A; Hutfless, Susan; Kim, Katherine; Lennon, Anne Marie; Canto, Marcia I; Jagannath, Sanjay B; Okolo, Patrick I; Shin, Eun Ji; Singh, Vikesh K

    2012-06-01

    Conventional plastic stents with a lumen typically have limited patency. The lumenless wing stent was engineered to overcome this problem. The objective of this study was to compare the incidence of early stent occlusion (symptomatic occlusion/cholangitis necessitating re-insertion within 90 days) for wing stents and conventional plastic stents. Patients with biliary pathology treated with plastic biliary stenting during the period 2003-2009 comprised the study cohort. Patients who had at least one biliary wing stent placed comprised the wing stent group, whereas patients who underwent only conventional stent plastic placement comprised the conventional stent group. Patients were stratified by indication: benign biliary strictures (group 1), malignant biliary strictures (group 2), or benign biliary non-stricture pathology (group 3). The association of stent type with the occurrence of primary outcome by indication was analyzed by use of multivariable logistic regression. Three-hundred and forty-six patients underwent 612 ERCP procedures with placement of plastic biliary stent(s). On multivariate analysis, early stent occlusion did not differ between the wing and conventional groups in groups 1, 2, and 3. Among patients who achieved primary outcome in group 2, significantly fewer patients in the wing group had cholangitis (6.7% vs. 39.1%, P = 0.03). Among patients who achieved primary outcome in group 3, significantly fewer patients in the wing group had cholangitis (10% vs. 50%, P = 0.03). Early stent occlusion was similar for wing stents and conventional plastic stents. Wing stents, however, were associated with a lower incidence of cholangitis in patients with malignant biliary obstruction and benign non-stricturing biliary pathology.

  5. Predictors of stent dysfunction after self-expandable metal stent placement for malignant gastric outlet obstruction: tumor ingrowth in uncovered stents and migration of covered stents.

    Science.gov (United States)

    Hori, Yasuki; Naitoh, Itaru; Hayashi, Kazuki; Ban, Tesshin; Natsume, Makoto; Okumura, Fumihiro; Nakazawa, Takahiro; Takada, Hiroki; Hirano, Atsuyuki; Jinno, Naruomi; Togawa, Shozo; Ando, Tomoaki; Kataoka, Hiromi; Joh, Takashi

    2017-10-01

    Endoscopic metallic stenting is widely accepted as a palliation therapy for malignant gastric outlet obstruction (GOO). However, the predictors of stent dysfunction have not been clarified. We aimed to evaluate the predictors, especially tumor ingrowth in uncovered self-expandable metallic stents (U-SEMS) and migration of covered self-expandable metallic stents (C-SEMS), which are the main causes related to the stent characteristics. In this multicenter retrospective study, we compared patients with U-SEMS and C-SEMS in terms of clinical outcomes, and predictors of stent dysfunction. In total, 252 patients (126 with U-SEMS and 126 with C-SEMS) were enrolled. There were no significant differences in technical success, clinical success, GOO score, or time to stent dysfunction. Tumor ingrowth was significantly more frequent in U-SEMS (U-SEMS, 11.90% vs. C-SEMS, 0.79%; p = 0.002), and stent migration was significantly more frequent for C-SEMS (C-SEMS, 8.73% vs. U-SEMS, 0.79%; p = 0.005). Karnofsky performance status (p = 0.04), no presence of ascites (p = 0.02), and insufficient (stent expansion (p = 0.003) were significantly associated with tumor ingrowth in U-SEMS. Meanwhile, a shorter stent length (p = 0.05) and chemotherapy (p = 0.03) were predictors of C-SEMS migration. Both U-SEMS and C-SEMS are effective with comparable patencies. Tumor ingrowth and stent migration are the main causes of stent dysfunction for U-SEMS and C-SEMS, respectively. With regard to stent dysfunction, U-SEMS might be a good option for patients receiving chemotherapy, while C-SEMS with longer stents for patients in good condition. (Clinical trial registration number: UMIN000024059).

  6. 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.

  7. A method to determine the kink resistance of stents and stent delivery systems according to international standards

    Directory of Open Access Journals (Sweden)

    Brandt-Wunderlich Christoph

    2016-09-01

    Full Text Available The kink behavior of vascular stents is of particular interest for clinicians, stent manufacturers and regulatory as a kinked stent generates a lumen loss in the stented vessel and can lead to in-stent restenosis. In this study methods to determine the kink resistance of stents and stent delivery systems according to the ISO 25539-2 and FDA guidance no. 1545 were presented. The methods are applicable for balloon expandable stents as well as for self-expanding stents and determine the lumen loss and residual diameter change dependent on the specific bending radius.

  8. 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.

  9. Long-term results after carotid artery stenting. Restenosis after carotid artery stenting using self-expandable stent

    International Nuclear Information System (INIS)

    Matsumoto, Yasushi; Furui, Eisuke; Tsuboi, Ken; Takahashi, Akira; Ezura, Masayuki

    2008-01-01

    Carotid artery stenting has emerged as an acceptable treatment alternative in patients with carotid artery stenosis. Although early clinical results of carotid artery stenting have shown promise, long, term clinical results remain less certain. We report the frequency, management, and clinical results of in-stent restenosis after carotid artery stenting using a self-expandable stent. Between August 1998 and September 2004, 80 carotid artery stenting procedures in 78 patients were performed. We evaluated 76 of the 80 procedures in 75 of the 78 patients treated during this period who had a minimum 6-month clinical and imaging (ultrasound and/or magnetic resonance angiography) follow-up. Recurrent stenosis (≥50%) after carotid artery stenting occurred in 3 (3.9%) patients. The recurrent stenosis occurred within one year after the procedure in all cases. The low rate of in-stent restenosis using self-expandable stent suggested that carotid artery stenting may be an effective alternative treatment for carotid artery stenosis, but more data of long-term follow-up are required. (author)

  10. Comparative Computed Flow Dynamic Analysis of Different Optimization Techniques in Left Main Either Provisional or Culotte Stenting.

    Science.gov (United States)

    Rigatelli, Gianluca; Dell'Avvocata, Fabio; Zuin, Marco; Giatti, Sara; Duong, Khanh; Pham, Trung; Tuan, Nguyen Si; Vassiliev, Dobrin; Daggubati, Ramesh; Nguyen, Thach

    2017-12-01

    Provisional and culotte are the most commonly used techniques in left main (LM) stenting. The impact of different post-dilation techniques on fluid dynamic of LM bifurcation has not been yet investigated. The aim of this study is to evaluate, by means of computational fluid dynamic analysis (CFD), the impact of different post-dilation techniques including proximal optimization technique (POT), kissing balloon (KB), POT-Side-POT and POT-KB-POT, 2-steps Kissing (2SK) and Snuggle Kissing balloon (SKB) on flow dynamic profile after LM provisional or culotte stenting. We considered an LM-LCA-LCX bifurcation reconstructed after reviewing 100 consecutive patients (mean age 71.4 ± 9.3 years, 49 males) with LM distal disease. The diameters of LAD and LCX were modelled according to the Finnet's law as following: LM 4.5 mm, LAD 3.5 mm, LCX 2.75 mm, with bifurcation angle set up at 55°. Xience third-generation stent (Abbot Inc., USA) was reconstructed and virtually implanted in provisional/cross-over and culotte fashion. POT, KB, POT-side-POT, POT-KB-POT, 2SK and SKB were virtually applied and analyzed in terms of the wall shear stress (WSS). Analyzing the provisional stenting, the 2SK and KB techniques had a statistically significant lower impact on the WSS at the carina, while POT seemed to obtain a neutral effect. In the wall opposite to the carina, the more physiological profile has been obtained by KB and POT with higher WSS value and smaller surface area of the lower WSS. In culotte stenting, at the carina, POT-KB-POT and 2SK had a very physiological profile; while at the wall opposite to the carina, 2SK and POT-KB-POT decreased significantly the surface area of the lower WSS compared to the other techniques. From the fluid dynamic point of view in LM provisional stenting, POT, 2SK and KB showed a similar beneficial impact on the bifurcation rheology, while in LM culotte stenting, POT-KB-POT and 2SK performed slightly better than the other techniques, probably

  11. Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters

    International Nuclear Information System (INIS)

    Chung, Hwan-Hoon; Lee, Seung Hwa; Cho, Sung Bum; Park, Hong Suk; Kim, Young Sik; Kang, Byung Chul; Frisoli, Joan K.; Razavi, Mahmood K.

    2008-01-01

    The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30-40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15 weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted

  12. 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.

  13. 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.

  14. Stent Design Affects Femoropopliteal Artery Deformation.

    Science.gov (United States)

    MacTaggart, Jason; Poulson, William; Seas, Andreas; Deegan, Paul; Lomneth, Carol; Desyatova, Anastasia; Maleckis, Kaspars; Kamenskiy, Alexey

    2018-03-23

    Poor durability of femoropopliteal artery (FPA) stenting is multifactorial, and severe FPA deformations occurring with limb flexion are likely involved. Different stent designs result in dissimilar stent-artery interactions, but the degree of these effects in the FPA is insufficiently understood. To determine how different stent designs affect limb flexion-induced FPA deformations. Retrievable markers were deployed into n = 28 FPAs of lightly embalmed human cadavers. Bodies were perfused and CT images were acquired with limbs in the standing, walking, sitting, and gardening postures. Image analysis allowed measurement of baseline FPA foreshortening, bending, and twisting associated with each posture. Markers were retrieved and 7 different stents were deployed across the adductor hiatus in the same limbs. Markers were then redeployed in the stented FPAs, and limbs were reimaged. Baseline and stented FPA deformations were compared to determine the influence of each stent design. Proximal to the stent, Innova, Supera, and SmartFlex exacerbated foreshortening, SmartFlex exacerbated twisting, and SmartControl restricted bending of the FPA. Within the stent, all devices except Viabahn restricted foreshortening; Supera, SmartControl, and AbsolutePro restricted twisting; SmartFlex and Innova exacerbated twisting; and Supera and Viabahn restricted bending. Distal to the stents, all devices except AbsolutePro and Innova exacerbated foreshortening, and Viabahn, Supera, Zilver, and SmartControl exacerbated twisting. All stents except Supera were pinched in flexed limb postures. Peripheral self-expanding stents significantly affect limb flexion-induced FPA deformations, but in different ways. Although certain designs seem to accommodate some deformation modes, no device was able to match all FPA deformations.

  15. Acute ST-Elevation Myocardial Infarction after Coronary Stent Fracture.

    Science.gov (United States)

    Rafighdust, Abbasali; Eshraghi, Ali

    2015-10-27

    The invention of the drug-eluting stent (DES) has brought about revolutionary changes in the field of interventional cardiology. In the DES era, in-stent restenosis has declined but new issues such as stent thrombosis have emerged. One of the emerging paradigms in the DES era is stent fracture. There are reports about stent fracture leading to in-stent restenosis or stent thrombosis. Most of these reports concern the Sirolimus-eluting stent. The present case is a representation of a Biolimus-eluting stent fracture. We introduce a 64-year-old male patient, for whom the BioMatrix stent was deployed in the right coronary artery. Five months after the implantation, he experienced acute myocardial infarction, with stent fracture leading to stent thrombosis being the causative mechanism. Another DES (Cypher) was used to manage this situation, and the final result was good.

  16. Causes and prevention of in-stent restenosis of vertebral artery origin after stenting

    International Nuclear Information System (INIS)

    Zhao Huipin; Li Shenmao; Zhang Guangping

    2010-01-01

    Vertebral artery stenosis is an important cause of posterior circulation stroke. Vertebral artery stenosis most commonly occurs at its origin site. In recent years, balloon angioplasty and stent implantation have been widely employed in the treatment of vertebral artery origin stenosis. However, the long term outcome of stent implantation is affected by in-stent restenosis. Multiple contributory factors have been identified, but clear understanding of the overall underlying mechanism remains an enigma. With the development of pathophysiology, prevention and treatment methods of in-stent restenosis have been improved. In recent years, drug-eluting stents, radioactive stents and magnetic stents have been widely applied. To some extent, these stents and drug therapy can solve the problem of restenosis. This article aims to review the clinical application and the up-to-date research progresses in preventing and managing vertebral artery origin restenosis. (authors)

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

    NARCIS (Netherlands)

    Klomp, M.

    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

  18. Research on shock wave characteristics in the isolator of central strut rocket-based combined cycle engine under Ma5.5

    Science.gov (United States)

    Wei, Xianggeng; Xue, Rui; Qin, Fei; Hu, Chunbo; He, Guoqiang

    2017-11-01

    A numerical calculation of shock wave characteristics in the isolator of central strut rocket-based combined cycle (RBCC) engine fueled by kerosene was carried out in this paper. A 3D numerical model was established by the DES method. The kerosene chemical kinetic model used the 9-component and 12-step simplified mechanism model. Effects of fuel equivalence ratio, inflow total temperature and central strut rocket on-off on shock wave characteristics were studied under Ma5.5. Results demonstrated that with the increase of equivalence ratio, the leading shock wave moves toward upstream, accompanied with higher possibility of the inlet unstart. However, the leading shock wave moves toward downstream as the inflow total temperature rises. After the central strut rocket is closed, the leading shock wave moves toward downstream, which can reduce risks of the inlet unstart. State of the shear layer formed by the strut rocket jet flow and inflow can influence the shock train structure significantly.

  19. [Late outlet strut fracture of an aortic Björk-Shiley and embolization of the prosthetic disc].

    Science.gov (United States)

    Brochet, E; Bougis de Brux, M A; Assayag, P; Benacin, Y; Gamerman, G; Guerot, C; Valère, P E

    1988-09-01

    A new case of late fracture of an outlet strut in a convexo-concave Björk-Shiley valve is reported. The fracture occurred 6 years after aortic implantation of the valve and was responsible for aorto-iliac embolization by the prosthetic disc and death of the patient from cardiogenic shock. This not uncommon complication of the Björk-Shiley valve prosthesis is usually ascribed to the relative fragility of its outlet strut welded to the metallic ring and subjected to strong pressures. Although most cases were observed within the first two years of prosthetic valve insertion, and mainly with valves manufactured in 1981 and 1982, our case and a few others demonstrate the possibility of late rupture. Cardiologists must be aware of this possible complication, since in some favourable cases it can be diagnosed at an early stage and the patient's life can be saved by an emergency operation.

  20. Structural FEM analysis of the strut-to-fuselage joint of a two-seat composite aircraft

    International Nuclear Information System (INIS)

    Vargas-Rojas, Erik; Camarena-Arellano, Diego; Hernández-Moreno, Hilario

    2014-01-01

    An analysis of a strut-to-fuselage joint is realized in order to evaluate the zones with a high probability of failure by means of a safety factor. The whole section is analyzed using the Finite Element Method (FEM) so as to estimate static resistance behavior, therefore it is necessary a numerical mock-up of the section, the mechanical properties of the Carbon-Epoxy (C-Ep) material, and to evaluate the applied loads. Results of the analysis show that the zones with higher probability of failure are found around the wing strut and the fuselage joint, with a safety factor lower than expected in comparison with the average safety factor used on aircrafts built mostly with metals

  1. Ununited fracture neck of femur treated with closed reduction and internal fixation with cancellous screw and fibular strut graft

    Directory of Open Access Journals (Sweden)

    Singh Daria

    2006-01-01

    Full Text Available Background: Ununited fracture neck of femur in young adults has been tackled in various ways. Methods: Twenty five patients of ununited fracture neck of femur in age group 21-55 years were treated by closed reduction, cancellous screw fixation and fibular strut graft and followed up for 2-6 years. Time gap between injury and operation was 6 weeks to 58 weeks. Five cases were previously fixed with various fixation devices. Results: Osseous union was achieved in 24 cases with average time of 18.16 weeks. Main complication encountered in follow-up was avascular necrosis of femoral head, others were joint stiffness and shortening. Functional end results were good to excellent in 24 cases. Conclusion: Closed reduction with internal fixation by cancellous screw and fibular strut grafting is easy and useful procedure.

  2. Comparison of self-expandable and balloon-expanding stents for hybrid ductal stenting in hypoplastic left heart complex.

    Science.gov (United States)

    Goreczny, Sebastian; Qureshi, Shakeel A; Rosenthal, Eric; Krasemann, Thomas; Nassar, Mohamed S; Anderson, David R; Morgan, Gareth J

    2017-07-01

    We aimed to compare the procedural and mid-term performance of a specifically designed self-expanding stent with balloon-expandable stents in patients undergoing hybrid palliation for hypoplastic left heart syndrome and its variants. The lack of specifically designed stents has led to off-label use of coronary, biliary, or peripheral stents in the neonatal ductus arteriosus. Recently, a self-expanding stent, specifically designed for use in hypoplastic left heart syndrome, has become available. We carried out a retrospective cohort comparison of 69 neonates who underwent hybrid ductal stenting with balloon-expandable and self-expanding stents from December, 2005 to July, 2014. In total, 43 balloon-expandable stents were implanted in 41 neonates and more recently 47 self-expanding stents in 28 neonates. In the balloon-expandable stents group, stent-related complications occurred in nine patients (22%), compared with one patient in the self-expanding stent group (4%). During follow-up, percutaneous re-intervention related to the ductal stent was performed in five patients (17%) in the balloon-expandable stent group and seven patients (28%) in self-expanding stents group. Hybrid ductal stenting with self-expanding stents produced favourable results when compared with the results obtained with balloon-expandable stents. Immediate additional interventions and follow-up re-interventions were similar in both groups with complications more common in those with balloon-expandable stents.

  3. Forgotten Ureteral Stents: An Avoidable Morbidity

    International Nuclear Information System (INIS)

    Murtaza, B.; Alvi, S.

    2016-01-01

    Objective: To assess the clinical presentation of forgotten ureteral stents and highlight the etiological factors resulting in the retention of these stents. Study Design: Observational study. Place and Duration of Study: Department of Urology, Armed Forces Institute of Urology, Rawalpindi, from January 2010 to Jun 2011. Methodology: Thirty-eight patients, with forgotten ureteral stents, retained for more than 6 months duration, were enrolled. A detailed evaluation was performed, along with the questions regarding the patients' opinion about the ureteral stents. They were specially asked whether they knew about the stents or were they formally informed regarding the stents. Subsequently, the patients were managed according to their clinical condition. Results: The male to female ratio was 2.1:1 aged 23 - 69 years, mean being 40.24 ± 12.59 years. The time of presentation after the ureteral stenting was 7 - 180 months (mean = 28.89 ± 33.435 years). Seven patients (18.4 percentage) reported with chronic kidney disease, including ESRD in two cases. Recurrent UTI was seen in 28 cases (73.6 percentage), calculus formed over the stents in 20 cases (52.6 percentage), and stent fragmented in 5 patients (13.1 percentage). Majority of patients, (n = 23, 60.5 percentage), were not even aware of the placement of these stents while 8 (21.0 percentage) knew but were reluctant about its removal. In 3 cases (7.8 percentage), the relatives knew about the stent but never informed the patients. The stent had been removed in 2 cases (5.2 percentage), but the other broken fragment was missed. One case (2.6 percentage) each had a misconception about the permanent placement of the stents like cardiac stents and regarding degradation of the stents in situ. Conclusion: Forgotten ureteral stents produce clinical features ranging from recurrent UTI to ESRD. This preventable urological complication is primarily due to the unawareness or ignorance of the patients and their relatives

  4. Fracture and embolization of a Celect inferior vena cava filter strut to the liver: A Case Report

    Energy Technology Data Exchange (ETDEWEB)

    Kim, So Hee; Song, Yun Gyu [Dept. of Radiology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon (Korea, Republic of)

    2017-07-15

    Inferior vena cava (IVC) filters are typically used for prophylaxis against pulmonary embolism. A new version of the Günther Tulip filter, the Celect IVC filter was introduced in April 2007. To the best of our knowledge, there are no reports commenting on Celect IVC filter fracture and fragment embolization to liver. We report a case in which the strut of the Celect IVC filter embolized to the liver.

  5. Role of jet spacing and strut geometry on the formation of large scale structures and mixing characteristics

    Science.gov (United States)

    Soni, Rahul Kumar; De, Ashoke

    2018-05-01

    The present study primarily focuses on the effect of the jet spacing and strut geometry on the evolution and structure of the large-scale vortices which play a key role in mixing characteristics in turbulent supersonic flows. Numerically simulated results corresponding to varying parameters such as strut geometry and jet spacing (Xn = nDj such that n = 2, 3, and 5) for a square jet of height Dj = 0.6 mm are presented in the current study, while the work also investigates the presence of the local quasi-two-dimensionality for the X2(2Dj) jet spacing; however, the same is not true for higher jet spacing. Further, the tapered strut (TS) section is modified into the straight strut (SS) for investigation, where the remarkable difference in flow physics is unfolded between the two configurations for similar jet spacing (X2: 2Dj). The instantaneous density and vorticity contours reveal the structures of varying scales undergoing different evolution for the different configurations. The effect of local spanwise rollers is clearly manifested in the mixing efficiency and the jet spreading rate. The SS configuration exhibits excellent near field mixing behavior amongst all the arrangements. However, in the case of TS cases, only the X2(2Dj) configuration performs better due to the presence of local spanwise rollers. The qualitative and quantitative analysis reveals that near-field mixing is strongly affected by the two-dimensional rollers, while the early onset of the wake mode is another crucial parameter to have improved mixing. Modal decomposition performed for the SS arrangement sheds light onto the spatial and temporal coherence of the structures, where the most dominant structures are found to be the von Kármán street vortices in the wake region.

  6. Fracture and embolization of a Celect inferior vena cava filter strut to the liver: A Case Report

    International Nuclear Information System (INIS)

    Kim, So Hee; Song, Yun Gyu

    2017-01-01

    Inferior vena cava (IVC) filters are typically used for prophylaxis against pulmonary embolism. A new version of the Günther Tulip filter, the Celect IVC filter was introduced in April 2007. To the best of our knowledge, there are no reports commenting on Celect IVC filter fracture and fragment embolization to liver. We report a case in which the strut of the Celect IVC filter embolized to the liver

  7. Self-Expandable Metal Stents and Trans-stent Light Delivery: Are Metal Stents and Photodynamic Therapy Compatible?

    Science.gov (United States)

    Wang, Luo-Wei; Li, Li-Bo; Li, Zhao-Shen; Chen, Yang K; Hetzel, Fred W.; Huang, Zheng

    2008-01-01

    Background and Objectives: Obstructive non-small cell lung cancer and obstructive esophageal cancer are US FDA approved indications of photodynamic therapy (PDT). The usefulness of PDT for the treatment of cholangiocarcinoma is currently under clinical investigation. Endoscopic stenting for lumen restoration is a common palliative intervention for those indications. It is important to assess whether self-expandable metal stents are compatible with trans-stent PDT light delivery. Study Design/Materials and Methods: Direct effects of various components of metal biliary (n = 2), esophageal (n = 2), and bronchial (n = 1) stents on PDT light transmittance and distribution were examined using a point or linear light source (630 or 652 nm diode laser). Resected pig biliary duct and esophageal wall tissues were used to examine the feasibility of PDT light delivery through the fully expanded metal stents. Results: While using a point light source, the metal components (thread and joint) of the stent could cause a significant shadow effect. The liner material (polytetrafluoroethylene or polyurethane) could cause various degrees of light absorption. When the stent was covered with a thin layer of biliary duct and esophageal tissues containing all wall layers, the shadow effect could be mitigated due to tissue scattering. Conclusions: This study clearly demonstrates that it is feasible to combine stenting and PDT for the treatment of luminal lesions. PDT light dose should be adjusted to counteract the reduction of light transmittance caused by the metal and liner materials of stent. PMID:18951422

  8. Serial 5-Year Evaluation of Side Branches Jailed by Bioresorbable Vascular Scaffolds Using 3-Dimensional Optical Coherence Tomography: Insights From the ABSORB Cohort B Trial (A Clinical Evaluation of the Bioabsorbable Everolimus Eluting Coronary Stent System in the Treatment of Patients With De Novo Native Coronary Artery Lesions).

    Science.gov (United States)

    Onuma, Yoshinobu; Grundeken, Maik J; Nakatani, Shimpei; Asano, Taku; Sotomi, Yohei; Foin, Nicolas; Ng, Jaryl; Okamura, Takayuki; Wykrzykowska, Joanna J; de Winter, Robbert J; van Geuns, Robert-Jan; Koolen, Jacques; Christiansen, Evald; Whitbourn, Robert; McClean, Dougal; Smits, Pieter; Windecker, Stephan; Ormiston, John A; Serruys, Patrick W

    2017-09-01

    The long-term fate of Absorb bioresorbable vascular scaffold (Abbott Vascular, Santa Clara, CA) struts jailing side branch ostia has not been clarified. We therefore evaluate serially (post-procedure and at 6 months, 1, 2, 3, and 5 years) the appearance and fate of jailed Absorb bioresorbable vascular scaffold struts. We performed 3-dimensional optical coherence tomographic analysis of the ABSORB Cohort B trial (A Clinical Evaluation of the Bioabsorbable Everolimus Eluting Coronary Stent System in the Treatment of Patients With De Novo Native Coronary Artery Lesions) up to 5 years using a novel, validated cut-plane analysis method. We included 29 patients with a total of 85 side branch ostia. From the 12 ostia which could be assessed in true serial fashion, 7 showed a pattern of initial decrease in the ostial area free from struts, followed by an increase in strut-free ostial area toward the end of the 5 years of follow-up. In a repeated-measures analysis with time as fixed variable and ostial area free from struts as dependent variable, we showed a numeric decrease in the estimated ostial area free from struts from 0.75 mm 2 (baseline) to 0.68 mm 2 (first follow-up visit at 6 months or 1 year) and 0.63 mm 2 (second follow-up visit at 2 or 3 years). However, from the second visit to the 5-year follow-up visit, there was a statistically significant increase from 0.63 to 0.89 mm 2 ( P =0.001). Struts overlying an ostium divided the ostium into compartments, and the number of these compartments decreased over time. This study showed that in most cases, the side branch ostial area free from struts initially decreased. However, with full scaffold bioresorption, the ostial area free from scaffold increased between 2 to 3 years and 5 years in the vast majority of patients. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00856856. © 2017 American Heart Association, Inc.

  9. Prevention of stent thrombosis: challenges and solutions

    Science.gov (United States)

    Reejhsinghani, Risheen; Lotfi, Amir S

    2015-01-01

    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. PMID:25657588

  10. A Stewart isolator with high-static-low-dynamic stiffness struts based on negative stiffness magnetic springs

    Science.gov (United States)

    Zheng, Yisheng; Li, Qingpin; Yan, Bo; Luo, Yajun; Zhang, Xinong

    2018-05-01

    In order to improve the isolation performance of passive Stewart platforms, the negative stiffness magnetic spring (NSMS) is employed to construct high static low dynamic stiffness (HSLDS) struts. With the NSMS, the resonance frequencies of the platform can be reduced effectively without deteriorating its load bearing capacity. The model of the Stewart isolation platform with HSLDS struts is presented and the stiffness characteristic of its struts is studied firstly. Then the nonlinear dynamic model of the platform including both geometry nonlinearity and stiffness nonlinearity is established; and its simplified dynamic model is derived under the condition of small vibration. The effect of nonlinearity on the isolation performance is also evaluated. Finally, a prototype is built and the isolation performance is tested. Both simulated and experimental results demonstrate that, by using the NSMS, the resonance frequencies of the Stewart isolator are reduced and the isolation performance in all six directions is improved: the isolation frequency band is increased and extended to a lower-frequency level.

  11. The indications and donor-site morbidity of tibial cortical strut autografts in the management of defects in long bones.

    Science.gov (United States)

    Lauthe, O; Soubeyrand, M; Babinet, A; Dumaine, V; Anract, P; Biau, D J

    2018-05-01

    Aims The primary aim of this study was to determine the morbidity of a tibial strut autograft and characterize the rate of bony union following its use. Patients and Methods We retrospectively assessed a series of 104 patients from a single centre who were treated with a tibial strut autograft of > 5 cm in length. A total of 30 had a segmental reconstruction with continuity of bone, 27 had a segmental reconstruction without continuity of bone, 29 had an arthrodesis and 18 had a nonunion. Donor-site morbidity was defined as any event that required a modification of the postoperative management. Union was assessed clinically and radiologically at a median of 36 months (IQR, 14 to 74). Results Donor-site morbidity occurred in four patients (4%; 95% confidence interval (CI) 1 to 10). One patient had a stress fracture of the tibia, which healed with a varus deformity, requiring an osteotomy. Two patients required evacuation of a haematoma and one developed anterior compartment syndrome which required fasciotomies. The cumulative probability of union was 90% (95% CI 80 to 96) at five years. The type of reconstruction (p = 0.018), continuity of bone (p = 0.006) and length of tibial graft (p = 0.037) were associated with the time to union. Conclusion The tibial strut autograft has a low risk of morbidity and provides adequate bone stock for treating various defects of long bones. Cite this article: Bone Joint J 2018;100-B:667-74.

  12. Ventilation Inception and Washout, Scaling, and Effects on Hydrodynamic Performance of a Surface Piercing Strut

    Science.gov (United States)

    Harwood, Casey; Young, Yin Lu; Ceccio, Steven

    2014-11-01

    High-lift devices that operate at or near a fluid free surface (such as surface-piercing or shallowly-submerged propellers and hydrofoils) are prone to a multiphase flow phenomenon called ventilation, wherein non-condensable gas is entrained in the low-pressure flow, forming a cavity around the body and dramatically altering the global hydrodynamic forces. Experiments are being conducted at the University of Michigan's towing tank using a canonical surface-piercing strut to investigate atmospheric ventilation. The goals of the work are (i) to gain an understanding of the dominant physics in fully wetted, partially ventilated, and fully ventilated flow regimes, (ii) to quantify the effects of governing dimensionless parameters on the transition between flow regimes, and (iii) to develop scaling relations for the transition between flow regimes. Using theoretical arguments and flow visualization techniques, new criteria are developed for classifying flow regimes and transition mechanisms. Unsteady transition mechanisms are described and mapped as functions of the governing non-dimensional parameters. A theoretical scaling relationship is developed for ventilation washout, which is shown to adequately capture the experimentally-observed washout boundary. This material is based upon work supported by the National Science Foundation Graduate Student Research Fellowship under Grant No. DGE 1256260. Support also comes from the Naval Engineering Education Center (Award No. N65540-10-C-003).

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

    International Nuclear Information System (INIS)

    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; Park, Hyungkeun

    2006-01-01

    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.)

  14. Genous endothelial progenitor cell-capturing stent system: a novel stent technology

    NARCIS (Netherlands)

    Klomp, Margo; Beijk, Marcel A. M.; de Winter, Robbert J.

    2009-01-01

    Drug-eluting stents have been demonstrated to significantly reduce clinical and angiographic restenosis in patients with coronary artery disease compared with bare-metal stents. Intuitively, however, a prohealing approach for the prevention of in-stent restenosis by promoting accelerated

  15. 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.

  16. PulmoStent : In Vitro to In Vivo Evaluation of a Tissue Engineered Endobronchial Stent

    NARCIS (Netherlands)

    Thiebes, Anja Lena; Kelly, Nicola; Sweeney, Caoimhe A.; McGrath, Donnacha J.; Clauser, Johanna; Kurtenbach, Kathrin; Gesche, Valentine N.; Chen, Weiluan; Kok, Robbert Jan; Steinseifer, Ulrich; Bruzzi, Mark; O’Brien, Barry J.; McHugh, Peter E.; Jockenhoevel, Stefan; Cornelissen, Christian G.

    Currently, there is no optimal treatment available for end stage tumour patients with airway stenosis. The PulmoStent concept aims on overcoming current hurdles in airway stenting by combining a nitinol stent with a nutrient-permeable membrane, which prevents tumour ingrowth. Respiratory epithelial

  17. 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.)

  18. Complication after self expandable metallic stent for esophageal cancer

    International Nuclear Information System (INIS)

    Nagahama, Takeshi; Maruyama, Michio; Kato, Kiyomi; Shinoura, Hiroshi; Hasegawa, Kumi; Takashima, Itaru; Ebuchi, Masakazu

    2003-01-01

    Major complications after placement of esophageal stent and airway stent were reviewed and evaluated. Four patients, including two patients with perforations and two patients with fistula formation, developed major complications after placement of a self expandable metallic stent. Two patients underwent additional radiation to improve stricture after stent placement. In one patient, stent placement was selected to improve esophageal stricture that occurred after radical radiation therapy. In one patient, migration of stent into the lesion caused a perforation. It can be concluded that additional radiation after stent placement increases the risk of complication. Stent migration also can lead to the risk of perforation. (author)

  19. The current role of vascular stents.

    Science.gov (United States)

    Busquet, J

    1993-09-01

    The limitations of percutaneous balloon angioplasty have favoured the development and the use of vascular endoprostheses or stents. These thin-walled metal devices maintain after expansion, an optimal and constant diameter for the vascular lumen. Restenosis, dissection, abrupt closure, residual stenosis or re-opened total occlusion represent appropriate indications for stenting. A large experience with non-coronary application of stents is currently available in iliac, femoro-popliteal and renal arteries, aorta, large veins.

  20. Management of JJ stent-related symptoms.

    Science.gov (United States)

    Papatsoris, Athanasios; Dellis, Athanasios; Daglas, George; Sanguedolce, Francesco

    2014-01-01

    Ureteric JJ stents are inserted in numerous pa- tients as a routine procedure. Nevertheless, the ideal JJ stent that does not cause any lower urinary tract symptoms has not been developed yet. Even special validated ques- tionnaires have been used for the assessment of JJ stent-related symtoms. For the management of such symtoms usually alpha-blockers are admin- istered. Also, studies have examined the efficacy and safety of anticholinergics and calcium channel blo- ckers. In this article we review the literature upon the management of JJ stent-related symptoms.

  1. Configuration affects parallel stent grafting results.

    Science.gov (United States)

    Tanious, Adam; Wooster, Mathew; Armstrong, Paul A; Zwiebel, Bruce; Grundy, Shane; Back, Martin R; Shames, Murray L

    2018-05-01

    A number of adjunctive "off-the-shelf" procedures have been described to treat complex aortic diseases. Our goal was to evaluate parallel stent graft configurations and to determine an optimal formula for these procedures. This is a retrospective review of all patients at a single medical center treated with parallel stent grafts from January 2010 to September 2015. Outcomes were evaluated on the basis of parallel graft orientation, type, and main body device. Primary end points included parallel stent graft compromise and overall endovascular aneurysm repair (EVAR) compromise. There were 78 patients treated with a total of 144 parallel stents for a variety of pathologic processes. There was a significant correlation between main body oversizing and snorkel compromise (P = .0195) and overall procedural complication (P = .0019) but not with endoleak rates. Patients were organized into the following oversizing groups for further analysis: 0% to 10%, 10% to 20%, and >20%. Those oversized into the 0% to 10% group had the highest rate of overall EVAR complication (73%; P = .0003). There were no significant correlations between any one particular configuration and overall procedural complication. There was also no significant correlation between total number of parallel stents employed and overall complication. Composite EVAR configuration had no significant correlation with individual snorkel compromise, endoleak, or overall EVAR or procedural complication. The configuration most prone to individual snorkel compromise and overall EVAR complication was a four-stent configuration with two stents in an antegrade position and two stents in a retrograde position (60% complication rate). The configuration most prone to endoleak was one or two stents in retrograde position (33% endoleak rate), followed by three stents in an all-antegrade position (25%). There was a significant correlation between individual stent configuration and stent compromise (P = .0385), with 31

  2. Device-specificity of vascular healing following implantation of bioresorbable vascular scaffolds and bioabsorbable-polymer metallic drugeluting stents in human coronary arteries. The ESTROFA OCT BVS vs. BP-DES study.

    Science.gov (United States)

    de la Torre Hernandez, Jose Maria; Gonzalo, Nieves; Otaegui, Imanol; Rumoroso, Jose R; Gutiérrez, Hipólito; Alfonso, Fernando; Marti, Gerard; Serrador Frutos, Ana; Brugaletta, Salvatore; Gomez Menchero, Antonio; Garcia Camarero, Tamara; Biagioni, Corina; Escaned, Javier

    2018-06-12

    We sought to compare vascular healing with bioresorbable everolimus-eluting vascular scaffolds (BVS) and drug-eluting stents with bioabsorbable polymers (BP-DES) at 6 and 12 months implanted both in same patients. Multicenter and prospective study including patients with at least two comparable lesions to treat. In every patient both BVS and BP-DES (Synergy™, Orsiro™ or Biomatrix Flex™) were implanted by lesion randomization. Patients included were evaluated with optical coherence tomography at 6 or 12 months (2:1). Finally, 68 patients had examination at 6 months and 27 patients at 12 months. Uncovered struts rates at 6 months were 1.7±3.2% for BVS and 5.3±5.6% for BP-DES (p=0.0001) and at 12 months 0.48±0.72% and 4.8±5% respectively (p=0.001). Rates of strut malapposition were significantly lower with BVS. There was no significant intra-patient correlation BP-DES / BVS for endpoints. Evaginations were more frequent and larger with BVS. Discontinuities in BVS were observed in 19.4% at 6 months and 14.3% at 12 months. Vascular healing with BVS and BP-DES could be more device-specific than patient-specific. At follow-up, BVS presented less uncovered or non-apposed struts than BP-DES but more frequent and larger evaginations. Discontinuities in BVS were relatively frequent at both time points.

  3. Endovascular AAA exclusion: will stents with hooks and barbs prevent stent-graft migration?

    Science.gov (United States)

    Malina, M; Lindblad, B; Ivancev, K; Lindh, M; Malina, J; Brunkwall, J

    1998-11-01

    To investigate if stents with hooks and barbs will improve stent-graft fixation in the abdominal aorta. Sixteen- to 24-mm-diameter Dacron grafts were deployed inside cadaveric aortas. The grafts were anchored by stents as in endovascular abdominal aortic aneurysm repair. One hundred thirty-seven stent-graft deployments were carried out with modified self-expanding Z-stents with (A) no hooks and barbs (n = 75), (B) 4 5-mm-long hooks and barbs (n = 39), (C) 8 10-mm-long, strengthened hooks and barbs (n = 19), or (D) hooks only (n = 4). Increasing longitudinal traction was applied to determine the displacement force needed to extract the stent-grafts. The radial force of the stents was measured and correlated to the displacement force. The median (interquartile range) displacement force needed to extract grafts anchored by stent A was 2.5 N (2.0 to 3.4), stent B 7.8 N (7.4 to 10.8), and stent C 22.5 N (17.1 to 27.9), p barbs added anchoring strength. During traction, the weaker barbs were distorted or caused intimal tears. The stronger barbs engaged the entire aortic wall. The radial force of the stents had no impact on fixation, while aortic calcification and graft oversizing had marginal effects. Stent barbs and hooks increased the fixation of stent-grafts tenfold, while the radial force of stents had no impact. These data may prove important in future endograft development to prevent stent-graft migration after aneurysm exclusion.

  4. Predictive Factors of In-Stent Restenosis in Renal Artery Stenting: A Retrospective Analysis

    International Nuclear Information System (INIS)

    Vignali, Claudio; Bargellini, Irene; Lazzereschi, Michele; Cioni, Roberto; Petruzzi, Pasquale; Caramella, Davide; Pinto, Stefania; Napoli, Vinicio; Zampa, Virna; Bartolozzi, Carlo

    2005-01-01

    Purpose. To retrospectively evaluate the role of clinical and procedural factors in predicting in-stent restenosis in patients with renovascular disease treated by renal artery stenting. Methods. From 1995 to 2002, 147 patients underwent renal artery stenting for the treatment of significant ostial atherosclerotic stenosis. Patients underwent strict clinical and color-coded duplex ultrasound follow-up. Ninety-nine patients (111 stents), with over 6 months of continuous follow-up (mean 22±12 months, range 6-60 months), were selected and classified according to the presence (group A, 30 patients, 32 lesions) or absence (group B, 69 patients, 79 lesions) of significant in-stent restenosis. A statistical analysis was performed to identify possible preprocedural and procedural predictors of restenosis considering the following data: sex, age, smoking habit, diabetes mellitus, hypertension, serum creatinine, cholesterol and triglyceride levels, renal artery stenosis grade, and stent type, length and diameter. Results. Comparing group A and B patients (χ 2 test), a statistically significant relation was demonstrated between stent diameter and length and restenosis: the risk of in-stent restenosis decreased when the stent was ≥6 mm in diameter and between 15 and 20 mm in length. This finding was confirmed by multiple logistic regression analysis. Stent diameter and length were proved to be significantly related to in-stent restenosis also when evaluating only patients treated by Palmaz stent (71 stents). Conclusion. Although it is based on a retrospective analysis, the present study confirms the importance of correct stent selection in increasing long-term patency, using stents of at least 6 mm in diameter and with a length of approximately 15-20 mm

  5. Structural Analysis of Shipping Casks, Vol. 9. Energy Absorption Capabilities of Plastically Deformed Struts Under Specified Impact Loading Conditions (Thesis)

    International Nuclear Information System (INIS)

    Davis, F.C.

    2001-01-01

    The purpose of this investigation was to determine the energy absorption characteristics of plastically deformed inclined struts under impact loading. This information is needed to provide a usable method by which designers and analysts of shipping casks for radioactive or fissile materials can determine the energy absorption capabilities of external longitudinal fins on cylindrical casks under specified impact conditions. A survey of technical literature related to experimental determination of the dynamic plastic behavior of struts revealed no information directly applicable to the immediate problem, especially in the impact velocity ranges desired, and an experimental program was conducted to obtain the needed data. Mild-steel struts with rectangular cross sections were impacted by free-falling weights dropped from known heights. These struts or fin specimens were inclined at five different angles to simulate different angles of impact that fins on a shipping cask could experience under certain accident conditions. The resisting force of the deforming strut was measured and recorded as a function of time by using load cells instrumented with resistance strain gage bridges, signal conditioning equipment, an oscilloscope, and a Polaroid camera. The acceleration of the impacting weight was measured and recorded as a function of time during the latter portion of the testing program by using an accelerometer attached to the drop hammer, appropriate signal conditioning equipment, the oscilloscope, and the camera. A digital computer program was prepared to numerically integrate the force-time and acceleration-time data recorded during the tests to obtain deformation-time data. The force-displacement relationships were then integrated to obtain values of absorbed energy with respect to deformation or time. The results for various fin specimen geometries and impact angles are presented graphically, and these curves may be used to compute the energy absorption capacity of

  6. 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.

  7. The effect of stent coating on stent deliverability: direct randomised comparison of drug eluting and bare metal stents using the same stent platform.

    Science.gov (United States)

    Siminiak, Tomasz; Link, Rafał; Wołoszyn, Maciej; Kałmucki, Piotr; Baszko, Artur

    2012-01-01

    There is certain experimental and clinical evidence indicating that the covering of bare metal stents (BMS) with drug eluting polymers to produce drug eluting stents (DES) results in increased stent stiffness and modifies the mechanical properties of the stent platform. In addition, it has been speculated that the mechanical performance of DES, compared to BMS, may be related to the type of polymer used to cover stents. We aimed at evaluating the deliverability of DES with a lactate based biodegradable polymer and BMS in patients with stable coronary artery disease in a prospective randomised study. One hundred eleven consecutive patients (age: 36-77, mean 58.8 years) scheduled for routine angioplasty due to stable coronary disease were randomised to receive BMS (Chopin II(TM), Balton, Poland) or paclitaxel eluting stent (Chopin Luc(TM), Balton, Poland) using the same metal platform. Only patients scheduled for angioplasty using the direct implantation technique of a single stent were randomised. The exclusion criteria included patients 〉 80 years, multivessel disease and reference diameter of the target vessel 〉 3.5 mm. In the BMS group (n = 55; 35 males and 20 females), the mean diameter of implanted stents was 3.09 ± 0.40 and the mean length was 11.37 ± 2.80, whereas in the DES group (n = 56; 34 males and 22 females) the mean stent sizes were 3.02 ± 0.34 and 17.90 ± 7.38 mm, respectively (p 〉 0.05 for length). The groups did not significantly differ regarding the frequency of stent implantation to particular coronary vessels. The direct stenting technique was attempted and failed, leading to the stents' implantation after predilatation in five patients in the BMS group and six patients in the DES group. Failure of stent implantation and subsequent implantation of another stent type was observed in no BMS patients and in one DES patient (NS). Although stent covering with lactate based drug eluting polymer may increase its stiffness, it does not affect

  8. 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.

  9. The forgotten ureteric JJ stent and its prevention: a prospective audit of the value of a ureteric stent logbook.

    Science.gov (United States)

    Thomas, A Z; Casey, R G; Grainger, R; McDermott, T; Flynn, R; Thornhill, J A

    2007-01-01

    Temporary ureteric stent insertion is an integral part of modern endo-urological practice. Delayed stent removal or forgotten stents are associated with increased patient morbidity and complications which are often difficult to manage. We prospectively audited our ureteric stent insertion and removal logbook system to determine the value and effectiveness of our stent follow-up. Over a 1-year period, 210 ureteric stents were inserted in our urological unit. Of these, 47 (22.4%) patients were unaccounted as having their stents removed within the stent logbooks. One patient was lost to follow-up and re-presented with stent encrustation 10 months later. Our results in this audit suggest that our system of ureteric stent follow-up is not effective. We have now introduced a new system that we feel is a safer and a satisfactory alternative to the stent logbooks. This includes a patient education leaflet and removal date scheduling prior to discharge from hospital.

  10. [The Predictive Factors of Stent Failure in the Treatment of Malignant Extrinsc Ureteral Obstruction Using Internal Ureteral Stents].

    Science.gov (United States)

    Matsuura, Hiroshi; Arase, Shigeki; Hori, Yasuhide; Tochigi, Hiromi

    2017-12-01

    In this study, we retrospectively reviewed the experiences at our single institute in the treatment of malignant extrinsic ureteral obstruction (MUO) using ureteral stents to investigate the clinical outcomes and the predictive factors of stent failure. In 52 ureters of 38 patients who had radiologically significant hydronephrosis due to MUO, internal ureteral stents (The BARD(R) INLAY(TM) ureteral stent set) were inserted. The median follow-up interval after the initial stent insertion was 124.5 days (4-1,120). Stent failure occurred in 8 ureters (15.4%) of the 7 patients. The median interval from the first stent insertion to stent failure was 88 days (1-468). A Cox regression multivariate analysis showed that the significant predictors of stent failure were bladder invasion. Based on the possibility of stent failure, the adaptation of the internal ureteral stent placement should be considered especially in a patient with MUO combined with bladder invasion.

  11. Monte Carlo Investigation on the Effect of Heterogeneities on Strut Adjusted Volume Implant (SAVI) Dosimetry

    Science.gov (United States)

    Koontz, Craig

    Breast cancer is the most prevalent cancer for women with more than 225,000 new cases diagnosed in the United States in 2012 (ACS, 2012). With the high prevalence, comes an increased emphasis on researching new techniques to treat this disease. Accelerated partial breast irradiation (APBI) has been used as an alternative to whole breast irradiation (WBI) in order to treat occult disease after lumpectomy. Similar recurrence rates have been found using ABPI after lumpectomy as with mastectomy alone, but with the added benefit of improved cosmetic and psychological results. Intracavitary brachytherapy devices have been used to deliver the APBI prescription. However, inability to produce asymmetric dose distributions in order to avoid overdosing skin and chest wall has been an issue with these devices. Multi-lumen devices were introduced to overcome this problem. Of these, the Strut-Adjusted Volume Implant (SAVI) has demonstrated the greatest ability to produce an asymmetric dose distribution, which would have greater ability to avoid skin and chest wall dose, and thus allow more women to receive this type of treatment. However, SAVI treatments come with inherent heterogeneities including variable backscatter due to the proximity to the tissue-air and tissue-lung interfaces and variable contents within the cavity created by the SAVI. The dose calculation protocol based on TG-43 does not account for heterogeneities and thus will not produce accurate dosimetry; however Acuros, a model-based dose calculation algorithm manufactured by Varian Medical Systems, claims to accurately account for heterogeneities. Monte Carlo simulation can calculate the dosimetry with high accuracy. In this thesis, a model of the SAVI will be created for Monte Carlo, specifically using MCNP code, in order to explore the affects of heterogeneities on the dose distribution. This data will be compared to TG-43 and Acuros calculated dosimetry to explore their accuracy.

  12. 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.

  13. Stent placement for esophageal strictures : an update

    NARCIS (Netherlands)

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

    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

  14. Incidence of definite stent thrombosis or in-stent restenosis after drug-eluting stent implantation for treatment of coronary in-stent restenosis. From western denmark heart registry

    DEFF Research Database (Denmark)

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

    2012-01-01

    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...

  15. Direct coronary stenting in reducing radiation and radiocontrast consumption

    International Nuclear Information System (INIS)

    Caluk, Jasmin; Osmanovic, Enes; Barakovic, Fahir; Kusljugic, Zumreta; Terzic, Ibrahim; Caluk, Selma; Sofic, Amela

    2010-01-01

    Coronary stenting is the primary means of coronary revascularization. There are two basic techniques of stent implantation: stenting with balloon predilatation of stenosis and stenting without predilatation (direct stenting). Limiting the time that a fluoroscope is activated and by appropriately managing the intensity of the applied radiation, the operator limits radiation in the environment, and this saves the exposure to the patient and all personnel in the room. Nephrotoxicity is one of the most important properties of radiocontrast. The smaller amount of radiocontrast used also provides multiple positive effects, primarily regarding the periprocedural risk for the patients with the reduced renal function. The goal of the study was to compare fluoroscopy time, the amount of radiocontrast, and expenses of material used in direct stenting and in stenting with predilatation. In a prospective study, 70 patients with coronary disease were randomized to direct stenting, or stenting with predilatation. Fluoroscopy time and radiocontrast use were significantly reduced in the directly stented patients in comparison to the patients stented with balloon-predilatation. The study showed a significant reduction of expenses when using a direct stenting method in comparison to stenting with predilatation. If the operator predicts that the procedure can be performed using direct stenting, he is encouraged to do so. Direct stenting is recommended for all percutaneous coronary interventions when appropriate conditions have been met. If direct stenting has been unsuccessful, the procedure can be converted to predilatation

  16. Stent Graft in Managing Juxta-Renal Aortoiliac Occlusion

    International Nuclear Information System (INIS)

    Prabhudesai, V.; Mitra, K.; West, D. J.; Dean, M. R. E.

    2003-01-01

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

  17. Basic Knowledge about Metal Stent Development

    Directory of Open Access Journals (Sweden)

    Seok Jeong

    2016-03-01

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

  18. 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.

  19. External stent for repair of secondary tracheomalacia.

    Science.gov (United States)

    Johnston, M R; Loeber, N; Hillyer, P; Stephenson, L W; Edmunds, L H

    1980-09-01

    Tracheomalacia was created in anesthetized piglets by submucosal resection of 3 to 5 tracheal cartilages. Measurements of airway pressure and flow showed that expiratory airway resistance is maximal at low lung volumes and is significantly increased by creation of the malacic segment. Cervical flexion increases expiratory airway resistance, whereas hyperextension of the neck reduces resistance toward normal. External stenting of the malacic segment reduces expiratory airway resistance, and the combination of external stenting and hyperextension restores airway resistance to normal except at low lung volume. Two patients with secondary tracheomalacia required tracheostomy and could not be decannulated after the indication for the tracheostomy was corrected. Both were successfully decannulated after external stenting of the malacic segment with rib grafts. Postoperative measurements of expiratory pulmonary resistance show a marked decrease from preoperative measurements. External stenting of symptomatic tracheomalacia reduces expiratory airway resistance by supporting and stretching the malacic segment and is preferable to prolonged internal stenting or tracheal resection.

  20. 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.

  1. Classic crush and DK crush stenting techniques.

    Science.gov (United States)

    Zhang, Jun-Jie; Chen, Shao-Liang

    2015-01-01

    Clinical data have supported the advantages of the double kissing (DK) crush technique, which consists of stenting the side branch (SB), balloon crush, first kissing, stenting the main vessel (MV) and final kissing balloon inflation, for complex coronary bifurcation lesions compared to other stenting techniques. Careful rewiring from the proximal cell of the MV stent to make sure the wire is in the true lumen of the SB stent is key to acquiring optimal angiographic results. Balloon anchoring from the MV, alternative inflation and each kissing inflation using large enough non-compliant balloons at high pressure, and the proximal optimisation technique are mandatory to improve both angiographic and clinical outcomes. Stratification of a given bifurcation lesion is recommended before decision making.

  2. Plastic Biliary Stent Migration During Multiple Stents Placement and Successful Endoscopic Removal Using Intra-Stent Balloon Inflation Technique: A Case Report and Literature Review.

    Science.gov (United States)

    Calcara, Calcedonio; Broglia, Laura; Comi, Giovanni; Balzarini, Marco

    2016-02-05

    Late migration of a plastic biliary stent after endoscopic placement is a well known complication, but there is little information regarding migration of a plastic stent during multiple stents placement. A white man was hospitalized for severe jaundice due to neoplastic hilar stenosis. Surgical eligibility appeared unclear on admission and endoscopy was carried out, but the first stent migrated proximally at the time of second stent insertion. After failed attempts with various devices, the migrated stent was removed successfully through cannulation with a dilation balloon. The migration of a plastic biliary stent during multiple stents placement is a possible complication. In this context, extraction can be very complicated. In our patient, cannulation of a stent with a dilation balloon was the only effective method.

  3. Upper Gastrointestinal Stent Insertion in Malignant and Benign Disorders

    Science.gov (United States)

    Kang, Hyoun Woo

    2015-01-01

    Upper gastrointestinal (GI) stents are increasingly being used to manage upper GI obstructions. Initially developed for palliative treatment of esophageal cancer, upper GI stents now play an emerging role in benign strictures of the upper GI tract. Because recurrent obstruction and stent-related complications are common, new modifications of stents have been implemented. Self-expandable metal stents (SEMS) have replaced older plastic stents. In addition, newly designed SEMS have been developed to prevent complications. This review provides an overview of the various types, indications, methods, complications, and clinical outcomes of upper GI stents in a number of malignant and benign disorders dividing the esophagus and gastroduodenum. PMID:26064817

  4. Stent insertion in patients with malignant biliary obstruction: problems of the Hanaro stent

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Jae Hyun; Seong, Chang Kyu; Shin, Tae Beom; Kim, Yong Joo [School of Medicine, Kyungpook National Univ., Daegu (Korea, Republic of); Jung, Gyoo Sik [School of Medicine, Kosin National Univ., Pusan (Korea, Republic of); Park, Byeung Ho [School of Medicine, Donga National Univ., Pusan (Korea, Republic of)

    2002-07-01

    To investigate the problems of the Hanaro stent (Solco Intermed, Seoul, Korea) when used in the palliative treatment of patients with inoperable malignant biliary obstruction. Between January 2000 and May 2001, the treatment of 46 patients with malignant biliary obstruction involved percutaneous placement of the Hanaro stent. Five patients encountered problems during removal of the stent's introduction system. The causes of obstruction were pancreatic carcinoma (n=2), cholangiocarcinoma (n=2), and gastric carcinoma with biliary invasion (n=1). In one patient, percutaneous transhepatic cholangiography and stent insertion were performed as a one-step procedure, while the others underwent conventional percutaneous transhepatic biliary drainage for at least two days prior to stent insertion. A self-expandable Hanaro stent, 8-10 mm in deameter and 50-100 mm in lengh, and made from a strand of nitinol wire, was used in all cases. Among the five patients who encountered problems, breakage of the olive tip occourred in three, upward displacement of the stent in two, and improper expansion of the distal portion of the stent, unrelated with the obstruction site, in one. The broken olive tip was pushed to the duodenum in two cases and to the peripheral intrahepatic duct in one. Where the stent migrated during withdrawal of its introduction system, an additional stent was inserted. In one case, the migrated stent was positioned near the liver capsule and the drainage catheter could not be removed. Although the number of patients in this study was limited, some difficulties were encountered in withdrawing the stent's introduction system. To prevent the occurrence of this unusual complication, the stent should be appropriately expansile, and shape in the olive tip should be considered.

  5. Self-expandable metallic stents vs. plastic stents for endoscopic biliary drainage in hepatocellular carcinoma.

    Science.gov (United States)

    Chung, Kwang Hyun; Lee, Sang Hyub; Park, Jin Myung; Lee, Jae Min; Ahn, Dong-Won; Ryu, Ji Kon; Kim, Yong-Tae

    2015-06-01

    The patency of self-expandable metallic stents (SEMS) is known to be better than plastic stents in the palliation of malignant biliary obstruction. However, data are scarce for obstructive jaundice caused by hepatocellular carcinoma (HCC). This study aimed to compare SEMSs and plastic stents for the palliation of obstructive jaundice in unresectable HCC. A total of 96 patients who underwent endoscopic retrograde biliary drainage with SEMSs or plastic stents were included in this retrospective analysis. The rate of successful biliary drainage, adverse events, stent patency duration, and patient survival were compared between the SEMS (n = 36) and plastic stent (n = 60) groups. The rate of successful biliary drainage was similar between the SEMS and plastic stent groups (25/36 [69.4 %] vs. 39/60 [65.0 %]; P = 0.655). Adverse events occurred in 6 patients (16.7 %) in the SEMS group and 13 patients (21.7 %) in the plastic stent group (P = 0.552). The median patency duration was also similar between the two groups (60 vs. 68 days; P = 0.396). The median patient survival was longer in the plastic stent group than in the SEMS group (123 vs. 48 days; P = 0.005). SEMSs were not superior to plastic stents for the palliation of malignant biliary obstruction in HCC with regard to successful drainage, stent patency, and adverse events. Patient survival was better in the plastic stent group. Given the lower cost, plastic stents could be a favorable option for malignant biliary obstruction caused by HCC. © Georg Thieme Verlag KG Stuttgart · New York.

  6. Clinical outcomes with the STENTYS self-apposing coronary stent in patients presenting with ST-segment elevation myocardial infarction: two-year insights from the APPOSITION III (A Post-Market registry to assess the STENTYS self-exPanding COronary Stent In AcuTe MyocardIal InfarctiON) registry.

    Science.gov (United States)

    Lu, Huangling; Grundeken, Maik J; Vos, Nicola S; IJsselmuiden, Alexander J J; van Geuns, Robert-Jan; Wessely, Rainer; Dengler, Thomas; La Manna, Alessio; Silvain, Johanne; Montalescot, Gilles; Spaargaren, René; Tijssen, Jan G P; Amoroso, Giovanni; de Winter, Robbert J; Koch, Karel T

    2017-08-04

    The APPOSITION III registry evaluated the feasibility and performance of the STENTYS self-apposing stent in an ST-segment elevation myocardial infarction (STEMI) population. This novel self-apposing stent device lowers stent strut malapposition rates and therefore carries the potential to prevent stent undersizing during primary percutaneous coronary intervention (PCI) in STEMI patients. To date, no long-term data are available using this device in the setting of STEMI. We aimed to evaluate the long-term clinical outcomes of the APPOSITION III registry. This was an international, prospective, multicentre post-marketing registry. The study population consisted of 965 STEMI patients. The primary endpoint, major adverse cardiac events (MACE), was defined as the composite of cardiac death, recurrent target vessel myocardial infarction (TV-MI), and clinically driven target lesion revascularisation (CD-TLR). At two years, MACE occurred in 11.2%, cardiac death occurred in 2.3%, TV-MI occurred in 2.3% and CD-TLR in 9.2% of patients. The two-year definite stent thrombosis (ST) rate was 3.3%. Incremental event rates between one- and two-year follow-up were 1.0% for TV-MI, 1.8% for CD-TLR, and 0.5% for definite ST. Post-dilation resulted in significantly reduced CD-TLR and ST rates at 30-day landmark analyses. Results were equivalent between the BMS and PES STENTYS subgroups. This registry revealed low rates of adverse events at two-year follow-up, with an incremental ST rate as low as 0.5% in the second year, demonstrating that the self-apposing technique is feasible in STEMI patients on long-term follow-up while using post-dilatation.

  7. The Björk-Shiley 70 degree convexo-concave prosthesis strut fracture problem (present state of information).

    Science.gov (United States)

    Ostermeyer, J; Horstkotte, D; Bennett, J; Huysmans, H; Lindblom, D; Olin, C; Orinius, E; Semb, G

    1987-04-01

    Between June 1980 and June 1983 4028 Björk-Shiley 70 degree convexo-concave prosthetic heart valves were distributed and implanted in Australia, Canada, Europe and South Africa. As of March 1986, a total of 52 outlet strut fractures (1.29%; 70% CL: 1.1%-1.5%) have been reported from 29 implant institutions in 12 countries. The majority (82.7%) occurred in Europe. Intervals between implantation and fracture were 13 days to 45.3 months (mean: 18.4 months; 70% CL: 16.6 months-20.1 months). The mortality rate after strut fracture was 78.7% (70% CL: 72.5%-84.9%). Upon stratification of the fracture by valve sizes and types it becomes evident that 75% (70% CL: 68.8%-81.2%) of all fractures are related to the sizes 29 mm to 33 mm (which virtually represent the same valve size) and predominantly to mitral valves (p less than 0.01). The large valves again have been stratified into two subsets, namely those fabricated from flanges originally machined as Björk-Shiley 60 degree convexo-concave valves (group I) and later produced valves machined initially to 70 degree specifications (group II). In group I the fracture rate was 5.2% (70% CL: 4.2%-6.2%) versus 1.6% (70% CL: 1.1%-2.1%) in group II (p less than 0.01), which identifies the group I 29 mm-33 mm Björk-Shiley 70 degree convexo-concave valves as the highest risk group for strut fracture. The rates are based upon all available information as of March 16, 1986.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Biodegradable magnesium-alloy stent:current situation in research

    International Nuclear Information System (INIS)

    Chen Hua; Zhao Xianxian

    2011-01-01

    In recent years, permanent metal stents are employed in the majority of interventional therapies; nevertheless, such kind of stents carries the problems of thrombosis and restenosis. Therefore, the biodegradable magnesium alloy stent has become the focus of attention. Theoretically, it has overcome the problems caused by permanent metal stents, so it is the development direction to use the biodegradable magnesium alloy in future. The authors believe that biodegradable magnesium alloy stents will be widely used in interventional procedures for many diseases. (authors)

  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......, the aneurysm had healed in the Nevo, but was still present in the Cypher stented segment. We hypothesize that aneurysm formation was induced by sirolimus and the polymer of the implanted stents, and that subsequent healing was possible in the Nevo stent after degradation of the polymer....

  10. Diseño e implementación de una tienda electrónica mediante STRUTS y SOAP

    OpenAIRE

    López Valladolid, Carmen Rocío

    2009-01-01

    Gracias al uso de Internet como medio de comunicación, las aplicaciones Web han cobrado una gran importancia y su uso se ha hecho muy común. Esta fuerte demanda de aplicaciones Web ha hecho que hayan nacido una serie de frameworks que facilitan su desarrollo. Este texto presenta una aplicación Web estándar implementada con Struts, uno de los frameworks OpenSource con más aceptación de los disponibles en el mercado para el desarrollo de aplicaciones Web. Esta aplicación se completa con una int...

  11. Simultaneous stent expansion/balloon deflation technique to salvage failed balloon remodeling.

    Science.gov (United States)

    Ladner, Travis R; He, Lucy; Davis, Brandon J; Froehler, Michael T; Mocco, J

    2016-04-01

    Herniation, with possible embolization, of coils into the parent vessel following aneurysm coiling remains a frequent challenge. For this reason, balloon or stent assisted embolization remains an important technique. Despite the use of balloon remodeling, there are occasions where, on deflation of the balloon, some coils, or even the entire coil mass, may migrate. We report the successful use of a simultaneous adjacent stent deployment bailout technique in order to salvage coil prolapse during balloon remodeling in three patients. Case No 1 was a wide neck left internal carotid artery bifurcation aneurysm, measuring 9 mm×7.9 mm×6 mm with a 5 mm neck. Case No 2 was a complex left superior hypophyseal artery aneurysm, measuring 5.3 mm×4 mm×5 mm with a 2.9 mm neck. Case No 3 was a ruptured right posterior communicating artery aneurysm, measuring 4 mm×4 mm×4.5 mm with a 4 mm neck. This technique successfully returned the prolapsed coil mass into the aneurysm sac in all cases without procedural complications. The closed cell design of the Enterprise VRD (Codman and Shurtleff Inc, Raynham, Massachusetts, USA) makes it ideal for this bailout technique, by allowing the use of an 0.021 inch delivery catheter (necessary for simultaneous access) and by avoiding the possibility of an open cell strut getting caught on the deflated balloon. We hope this technique will prove useful to readers who may find themselves in a similar predicament. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  12. Endoscopic bilateral stent-in-stent placement for malignant hilar obstruction using a large cell type stent.

    Science.gov (United States)

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

    2016-12-01

    Bilateral stent-in-stent (SIS) self-expandable metal stent placement is technically challenging for palliation of unresectable malignant hilar obstruction. In the SIS technique, the uniform large cell type biliary stent facilitates contralateral stent deployment through the mesh of the first metallic stent. This study aimed to assess the technical success and clinical effectiveness of this technique with a uniform large cell type biliary stent. Thirty-one patients who underwent bilateral SIS placement using a large cell type stent were reviewed retrospectively. All patients showed malignant hilar obstruction (Bismuth types II, III, IV) with different etiologies. Sixteen (51.6%) patients were male. The mean age of the patients was 67.0+/-14.0 years. Most patients were diagnosed as having hilar cholangiocarcinoma (58.1%) and gallbladder cancer (29.0%). Technical success rate was 83.9%. Success was achieved more frequently in patients without masses obstructing the biliary confluence (MOC) than those with MOC (95.2% vs 60.0%, P=0.03). Functional success rate was 77.4%. Complications occurred in 29.0% of the patients. These tended to occur more frequently in patients with MOC (50.0% vs 19.0%, P=0.11). Median time to recurrent biliary obstruction was 188 days and median survival was 175 days. The large cell type stent can be used efficiently for bilateral SIS placement in malignant hilar obstruction. However, the risk of technical failure increases in patients with MOC, and caution is needed to prevent complications for these patients.

  13. Partially Covered Metal Stents May Not Prolong Stent Patency Compared to Uncovered Stents in Unresectable Malignant Distal Biliary Obstruction

    Science.gov (United States)

    Kim, Jae Yun; Ko, Gyu Bong; Lee, Tae Hoon; Park, Sang-Heum; Lee, Yun Nah; Cho, Young Sin; Jung, Yunho; Chung, Il-Kwun; Choi, Hyun Jong; Cha, Sang-Woo; Moon, Jong Ho; Cho, Young Deok; Kim, Sun-Joo

    2017-01-01

    Background/Aims Controversy still exists regarding the benefits of covered self-expandable metal stents (SEMSs) compared to uncovered SEMSs. We aimed to compare the patency and stent-related adverse events of partially covered SEMSs (PC-SEMSs) and uncovered SEMSs in unresectable malignant distal biliary obstruction. Methods A total of 134 patients who received a PC-SEMS or uncovered SEMS for palliation of unresectable malignant distal biliary obstruction were reviewed retrospectively. The main outcome measures were stent patency, stent-related adverse events, and overall survival. Results The median stent patency was 118 days (range, 3 to 802 days) with PC-SEMSs and 105 days (range, 2 to 485 days) with uncovered SEMSs (p=0.718). The overall endoscopic revision rate due to stent dysfunction was 36.6% (26/71) with PC-SEMSs and 36.5% (23/63) with uncovered SEMSs (p=0.589). Tumor ingrowth was more frequent with uncovered SEMSs (4.2% vs 19.1%, p=0.013), but migration was more frequent with PC-SEMSs (11.2% vs 1.5%, p=0.04). The incidence of stent-related adverse events was 2.8% (2/71) with PC-SEMSs and 9.5% (6/63) with uncovered SEMSs (p=0.224). The median overall survival was 166 days with PC-SEMSs and 168 days with uncovered SEMSs (p=0.189). Conclusions Compared to uncovered SEMSs, PC-SEMSs did not prolong stent patency in unresectable malignant distal biliary obstruction. Stent migration was more frequent with PC-SEMSs. However, tumor ingrowth was less frequent with PC-SEMSs compared to uncovered SEMSs. PMID:28208003

  14. Flexibility and trackability of laser cut coronary stent systems.

    Science.gov (United States)

    Szabadíts, Péter; Puskás, Zsolt; Dobránszky, János

    2009-01-01

    Coronary stents are the most important supports in present day cardiology. Flexibility and trackability are two basic features of stents. In this paper, four different balloon-expandable coronary stent systems were investigated mechanically in order to compare their suitability. The coronary stent systems were assessed by measurements of stent flexibility as well as by comparison of forces during simulated stenting in a self-investigated coronary vessel model. The stents were cut by laser from a single tube of 316L stainless steel or L-605 (CoCr) cobalt chromium alloy. The one-and four-point bending tests were carried out to evaluate the stent flexibility E x I (Nmm(2)), under displacement control in crimped and expanded configurations. The flexibility of stents would be rather dependent on the design than on raw material. In general a more flexible stent needs lower tracking force during the implantation. The L-605 raw material stents need lower track force to pass through in the vessel model than the 316L raw material stents. The sort and long stents passed through the curved vessel model in different ways. The long stents nestled to the vessel wall at the outer arc and bent, while the short stents did not bend in the curve, only the delivery systems bent.

  15. Tracheal obstruction caused by an expandable metallic stent: a case of successful removal of the stent.

    Science.gov (United States)

    Okuyama, Hiroomi; Kubota, Akio; Kawahara, Hisayoshi; Oue, Takaharu; Nose, Satoko; Ihara, Toshiyuki

    2005-07-01

    We report a case of tracheal obstruction caused by an expandable metallic stent. A 3-month-old girl with severe tracheomalacia had a placement of a Palmaz stent. At 3 years of age, she developed progressive dyspnea. The CT scan showed tracheal obstruction caused by granulation tissue over the stent. At operation, the stent was found to have penetrated the posterior tracheal wall. Under partial cardiopulmonary bypass, the stent was removed along with the membranous wall of the trachea, and the trachea was reconstructed using slide tracheoplasty. Tracheal obstruction is one of the serious complications caused by an expandable metallic stent. Direct open approach to the trachea under cardiopulmonary bypass is thought to be a safe way to manage this problem.

  16. TOKYO criteria 2014 for transpapillary biliary stenting.

    Science.gov (United States)

    Isayama, Hiroyuki; Hamada, Tsuyoshi; Yasuda, Ichiro; Itoi, Takao; Ryozawa, Shomei; Nakai, Yousuke; Kogure, Hirofumi; Koike, Kazuhiko

    2015-01-01

    It is difficult to carry out meta-analyses or to compare the results of different studies of biliary stents because there is no uniform evaluation method. Therefore, a standardized reporting system is required. We propose a new standardized system for reporting on biliary stents, the 'TOKYO criteria 2014', based on a consensus among Japanese pancreatobiliary endoscopists. Instead of stent occlusion, we use recurrent biliary obstruction, which includes occlusion and migration. The time to recurrent biliary obstruction was estimated using Kaplan-Meier analysis with the log-rank test. We can evaluate both plastic and self-expandable metallic stents (uncovered and covered). We also propose specification of the cause of recurrent biliary obstruction, identification of complications other than recurrent biliary obstruction, indication of severity, measures of technical and clinical success, and a standard for clinical care. Most importantly, the TOKYO criteria 2014 allow comparison of biliary stent quality across studies. Because blocked stents can be drained not only using transpapillary techniques but also by an endoscopic ultrasonography-guided transmural procedure, we should devise an evaluation method that includes transmural stenting in the near future. © 2014 The Authors. Digestive Endoscopy © 2014 Japan Gastroenterological Endoscopy Society.

  17. Experimental use of new absorbable tracheal stent.

    Science.gov (United States)

    Schopf, Luciano F; Fraga, José Carlos; Porto, Rodrigo; Santos, Luis A; Marques, Douglas R; Sanchez, Paulo R; Meyer, Fabíola S; Ulbrich, Jane M

    2017-11-16

    Silicone and metallic stents are not effective in children with tracheobronchial stenosis or tracheomalacia. Herein, we aimed to evaluate the clinical manifestations and histological reaction of rabbit trachea to the presence of a new poly(lactic-co-glycolic acid) with polyisoprene (PLGA/PI) polymer absorbable stent. Fourteen adult white rabbits (weight, 3.0-3.5kg) were randomly assigned to three groups: Group I (n=6): PLGA/PI spiral stent; Group II (n=6): PLGA/PI fragment; and Group III (n=2): controls. After a longitudinal incision on three cervical tracheal rings, the stents and fragments were inserted into the trachea and fixed onto the lateral wall with nonabsorbable sutures. The stented group showed significantly more stridor at rest (p=0.0041), agitation (p=0.014), and use of accessory muscles (p=0.0002) and required more emergency endoscopies than the fragment group. Further, it showed significantly more remarkable histological inflammatory damage than the fragment and control groups (p=0.002). The new PLGA/PI polymeric stent implanted into the trachea of rabbits caused more clinical manifestations and histologically verified inflammatory reaction than the PLGA/PI polymeric fragment. Future studies should be aimed at reducing the stent-wall thickness. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. 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.

  19. Stent underexpansion in angiographic guided percutaneous coronary intervention, despite adjunctive balloon post-dilatation, in drug eluting stent era

    Directory of Open Access Journals (Sweden)

    Mehrdad Taherioun

    2014-01-01

    Full Text Available BACKGROUND: Stent underexpansion is the most powerful predictor of long-term stent patency and clinical outcome. The purpose of this study was to evaluate the incidence and predictors of stent underexpansion despite adjunctive post-dilatation with non-compliant balloon. METHODS: After elective coronary stent implantation and adjunctive post-dilatation with non-compliant balloon and optimal angiographic result confirmed by the operator, intravascular ultrasound (IVUS was performed for all the treated lesions. If the treated lesions fulfilled the IVUS criteria, they are considered as the optimal stent group; if not, they are considered as the suboptimal group. RESULTS: From 50 patients enrolled in this study 39 (78% had optimal stent deployment and 11 (22% had suboptimal stent deployment. In the suboptimal group 7 (14% had underexpansion, 2 (4% malposition, and 2 (4% had asymmetry. There were no stent edge dissections detected by IVUS. We did not find any correlation between lesion calcification, ostial lesions, stent length, and stent underexpansion. Stent diameter ≤ 2.75 mm had a strong correlation with stent underexpansion. CONCLUSION: Despite adjunctive post-dilatation with noncompliant balloon, using a relatively small stent diameter was a strong predictor for underexpansion. IVUS guided percutaneous coronary intervention (PCI may be considered for drug eluting stent (DES implantation in relatively small vessels.   Keywords: Stent, Percutaneous Coronary Intervention, Ultrasound, Post-dilatation 

  20. Stent-assisted angioplasty for intracranial atherosclerosis

    International Nuclear Information System (INIS)

    Nakahara, Toshinori; Sakamoto, Shigeyuki; Hamasaki, Osamu; Sakoda, Katsuaki

    2002-01-01

    We report on two patients with intracranial atherosclerosis of the carotid artery or vertebral artery treated with stent-assisted angioplasty. Both patients have severe intracranial atherosclerosis (>70%) with refractory symptoms despite optimal medical treatment. In both patients, a coronary balloon-expandable stent was successfully placed using a protective balloon technique without procedural complications. The patients were asymptomatic and neurologically intact at a mean clinical follow-up of 13 months. Follow-up angiograms did not show restenosis 3 or 4 months after procedure, respectively. Stent-assisted angioplasty for intracranial atherosclerosis in the elective patient has proven effective, with an acceptable low rate of morbidity and mortality. (orig.)

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    the randomised BASKET-PROVE trial (sirolimus-eluting stent vs. everolimus-eluting stent vs. bare metal stent in large-vessel stenting). The primary endpoint was the combined two-year rate of cardiovascular death or non-fatal myocardial infarction (MI). Secondary endpoints were each component of the primary...... implantation in large vessels was associated with a reduction in both TVR and the combined endpoint consisting of cardiovascular death/MI. Thus, DES use improves both efficacy and safety. These findings support the use of DES in NSTE-ACS patients....

  2. Treatment of Post-Stent Gastroesophageal Reflux by Anti-Reflux Z-Stent

    International Nuclear Information System (INIS)

    Davies, Roger Philip; Kew, Jacqueline; Byrne, Peter D.

    2000-01-01

    Severe symptoms of heartburn and retrosternal pain consistent with gastro-esophageal reflux (GER) developed in a patient following placement of a conventional self-expanding 16-24-mm-diameter x 12-cm-long esophageal stent across the gastroesophageal junction to treat an obstructing esophageal carcinoma. A second 18-mm-diameter x 10-cm-long esophageal stent with anti-reflux valve was deployed coaxially and reduced symptomatic GER immediately. Improvement was sustained at 4-month follow-up. An anti-reflux stent can be successfully used to treat significant symptomatic GER after conventional stenting

  3. [Developments in percutaneous coronary intervention and coronary stents].

    Science.gov (United States)

    Simsek, C; Daemen, J; Zijlstra, F

    2014-01-01

    In The Netherlands, more than 30.000 patients undergo a percutaneous coronary intervention every year, during which a coronary stent implantation will be performed in 90% of the cases. It is estimated that more than 5 million coronary stent implantations will be performed worldwide this year. While these numbers are impressive, however, coronary stents still have as a limitation the possibility of stent thrombosis. This has been and is an important stimulus for the development of both coronary stents, from a bare metal stent via a drug eluting stent to the present-day development of bio-absorbable stents, and anti-platelet drugs,from acenocoumarol to thieropyridines. The possibility of shortening the period of use of this powerful medication by developing new kinds of non-thrombogenic stents would, for example, make it possible to achieve significant reductions in subsequent bleeding during (dental) procedures.

  4. Covered duodenal self-expandable metal stents prolong biliary stent patency in double stenting: The largest series of bilioduodenal obstruction.

    Science.gov (United States)

    Hori, Yasuki; Naitoh, Itaru; Hayashi, Kazuki; Kondo, Hiromu; Yoshida, Michihiro; Shimizu, Shuya; Hirano, Atsuyuki; Okumura, Fumihiro; Ando, Tomoaki; Jinno, Naruomi; Takada, Hiroki; Togawa, Shozo; Joh, Takashi

    2018-03-01

    Endoscopic biliary and duodenal stenting (DS; double stenting) is widely accepted as a palliation therapy for malignant bilioduodenal obstruction. The aim of the current study was to investigate the patency and adverse events of duodenal and biliary stents in patients with DS. Patients who underwent DS from April 2004 to March 2017 were analyzed retrospectively with regard to clinical outcomes and predictive factors of recurrent biliary and duodenal obstruction (recurrent biliary obstruction [RBO] and recurrent duodenal obstruction [RDO]). A total of 109 consecutive patients was enrolled. Technical success of DS was achieved in 108 patients (99.1%). Symptoms due to biliary and duodenal obstruction were improved in 89 patients (81.7%). RBO occurred in 25 patients (22.9%) and RDO in 13 (11.9%). The median times to RBO and RDO from DS were 87 and 76 days, respectively. Placement of a duodenal uncovered self-expandable metal stent (U-SEMS) was significantly associated with RBO in the multivariable analysis (P = 0.007). Time to RBO was significantly longer in the duodenal covered self-expandable metal stent group than in the U-SEMS group (P = 0.003). No predictive factors of RDO were detected, and duodenal stent type was not associated with the time to RDO (P = 0.724). Double stenting was safe and effective for malignant bilioduodenal obstruction. Duodenal U-SEMS is a risk factor for RBO. The covered self-expandable metal stent is the preferred type of duodenal SEMS in patients with DS (Clinical trial registration number: UMIN000027606). © 2017 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

  5. Stent Fracture and Reocclusion After Placement of a Single Self-Expanding Stent in the Common Iliac Artery and Endovascular Treatment

    International Nuclear Information System (INIS)

    Higashiura, Wataru; Sakaguchi, Shoji; Morimoto, Kengo; Kichikawa, Kimihiko

    2008-01-01

    We present a case of fracture of a single self-expanding stent placed in the common iliac artery (CIA). An 80-year-old woman underwent placement of a self-expanding stent for CIA occlusion. Stent fracture and reocclusion were detected after 18 months. Successful revascularization was achieved using a stent-in-stent maneuver. The possibility of stent fracture with reocclusion should be considered following treatment with a single self-expanding stent for CIA occlusion.

  6. Functional Self-Expandable Metal Stents in Biliary Obstruction

    Science.gov (United States)

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

    2013-01-01

    Biliary stents are widely used not only for palliative treatment of malignant biliary obstruction but also for benign biliary diseases. Each plastic stent or self-expandable metal stent (SEMS) has its own advantages, and a proper stent should be selected carefully for individual condition. To compensate and overcome several drawbacks of SEMS, functional self-expandable metal stent (FSEMS) has been developed with much progress so far. This article looks into the outcomes and defects of each stent type for benign biliary stricture and describes newly introduced FSEMSs according to their functional categories. PMID:24143314

  7. Biomimicry, vascular restenosis and coronary stents.

    Science.gov (United States)

    Schwartz, R S; van der Giessen, W J; Holmes, D R

    1998-01-01

    Biomimicry is in its earliest stages and is being considered in the realm of tissue engineering. If arterial implants are to limit neointimal thickening, purely passive structures cannot succeed. Bioactivity must be present, either by pharmacologic intervention or by fabricating a 'living stent' that contains active cellular material. As tissue engineering evolves, useful solutions will emerge from applying this knowledge directly to vascular biologic problems resulting from angioplasty, stenting, and vascular prosthesis research.

  8. Nasolacrimal Polyurethane Stent: Complications with CT Correlation

    International Nuclear Information System (INIS)

    Pinto, Isabel T.; Paul, Laura; Grande, Carlos

    1998-01-01

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

  9. Hemi-Intravascular Stenting for Supermicrosurgical Anastomosis

    OpenAIRE

    Kensuke Tashiro, MD; Shuji Yamashita, MD; Mitsunaga Narushima, MD; Isao Koshima, MD; Shimpei Miyamoto, MD

    2017-01-01

    Background:. Although supermicrosurgical anastomosis is a widely known reconstructive microsurgical technique, it is difficult to perform. To expand the clinical use of supermicrosurgery, we used hemi-intravascular stenting (hemi-IVaS), which is performed by inserting an intravascular stent into one side of the vessel. We conducted lymphaticovenular anastomosis, free perforator flap transfer, and fingertip replantation with supermicrosurgical anastomosis using hemi-IVaS technique and examined...

  10. Renal artery stent angioplasty for renovascular hypertension

    International Nuclear Information System (INIS)

    Li Gang; Li Haiqing; Wang Lin

    2005-01-01

    Objective: To evaluate the therapeutic results of expandable stent for treatment of atherosclerotic renovascular obstructive disease. Methods: 15 patients (10 men and 5 women, 41-75 years old; mean age, 52 years) with renal arterial hypertension underwent renal stent angioplasty including renal arterial stenosis 89%(n=13) and fully obstruction without function in 2, of which 2 patients had bilateral involvement. The stenotic range of all arterial segments showed 60% to 90% width of the normal arterial diameter. 16 stents were implanted under the guidance of fluoroscopy. The most of stents implanted were Palmaz (n=12, 75%) with regular clinical and angiographic follow up. Results: Technical success (residual stenosis <30%) was achieved in all patients without serious complication. During the follow-up (6-15 months; mean, 8 ± 4 months), hypertension was improved in 9 patients and cured in 4 patients with a total benefit of 86% and no efficacy in 2(13%). The average systolic blood pressure decreased from 27.12 ± 3.09 kPa to 18.62 ± 3.12 kPa and the average diastolic blood pressure decreased from 17.73 ± 1.92 kPa to 11.12 ± 2.43 kPa after stent treatment (P<0.05). Serum creatinine remained stable in 60% (n=9) patients with improvement in 33% (n=5) and worsened in 6% (n=1) patients. Follow-up angiography was performed in all patients with 1 case of a restenosis. 6 months after expanding through stent by using balloon, the two follow up angiographies showed a stable restenosis about 20%. Conclusions: Percutaneous transluminal stent placement is highly beneficial for patients who had renal arterial obstructive disease. The success of stent angioplasty of complete obstructive renal arteries reveals wide prospects for interventional method. (authors)

  11. Outcomes of the single-stent versus kissing-stents technique in asymmetric complex aortoiliac bifurcation lesions.

    Science.gov (United States)

    Suh, Yongsung; Ko, Young-Guk; Shin, Dong-Ho; Kim, Jung-Sun; Kim, Byeong-Keuk; Choi, Donghoon; Hong, Myeong-Ki; Jang, Yangsoo

    2015-07-01

    This study investigated the outcomes of single-stent vs kissing-stents techniques in asymmetric complex aortoiliac bifurcation (ACAB) lesions. We retrospectively investigated 80 consecutive patients (69 males, 66.6 ± 8.7 years) treated with a single stent and 30 patients (26 males, 67.1 ± 7.7 years) treated with kissing stents for ACAB between January 2005 and December 2012 from a single-center cohort. A ACAB lesion was defined as a symptomatic unilateral common iliac artery stenosis (>50%) combined with intermediate stenosis (30%-50%) in the contralateral common iliac artery ostium. The primary end point was the primary patency of the ACAB. The baseline clinical characteristics did not differ significantly between the single-stent and the kissing-stents group. Technical success was achieved in all patients. The single-stent group required fewer stents (1.3 ± 0.5 vs 2.3 ± 0.8; P stent group (3%) required bailout kissing stents because of plaque shift to the contralateral side. The major complication rates were 8% in single-stent vs 13% in the kissing-stent group, which was similar (P = .399). At 3 years, the single-stent and kissing-stents group had similar rates of primary patency (89% vs 87%; P = .916) and target lesion revascularization-free survival (93% vs 87%; P = .462). The single-stent technique in ACAB was safe and showed midterm outcomes comparable with those of kissing stents. Considering the benefits, such as fewer stents, less bilateral femoral access, and the availability of contralateral access for future intervention, the single-stent technique may be an advantageous treatment option in ACAB. Copyright © 2015 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

  12. Ureteral stent discomfort: Etiology and management

    Directory of Open Access Journals (Sweden)

    Ricardo Miyaoka

    2009-01-01

    Full Text Available Objectives : To review the evidence-based literature on the causes, characteristics, and options to manage double J stent-related symptoms. Methods : We performed a Medline database assessment on papers that investigated the prevalence, mechanisms, risk factors, bothersome and management of double-J stent-related symptoms. Articles in English were reviewed and summarized. Results : Stent-related symptoms have a high prevalence and may affect over 80% of patients. They include irritative voiding symptoms including frequency, urgency, dysuria, incomplete emptying; flank and suprapubic pain; incontinence, and hematuria. Assessment tools are important to determine their intensity and allow for comparisons between different points in the timeline. The Urinary Stent Symptom Questionnaire (USSQ is the most proper tool used for this purpose. Management should be focused on the prevention and management of symptoms. In this sense, research has focused on new materials and stent designs that would be more compatible to the physiologic properties of the urinary tract and medications that can ameliorate the sensitivity and motor response of the bladder. Conclusions : Stent-related symptoms are very common in the Urological clinical setting. It is of major importance for the urologist to understand their physiopathology and to be familiar with ways to avoid or manage them.

  13. 4D phase contrast flow imaging for in-stent flow visualization and assessment of stent patency in peripheral vascular stents – A phantom study

    International Nuclear Information System (INIS)

    Bunck, Alexander C.; Jüttner, Alena; Kröger, Jan Robert; Burg, Matthias C.; Kugel, Harald; Niederstadt, Thomas; Tiemann, Klaus; Schnackenburg, Bernhard; Crelier, Gerard R.

    2012-01-01

    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

  14. 4D phase contrast flow imaging for in-stent flow visualization and assessment of stent patency in peripheral vascular stents--a phantom study.

    Science.gov (United States)

    Bunck, Alexander C; Jüttner, Alena; Kröger, Jan Robert; Burg, Matthias C; Kugel, Harald; Niederstadt, Thomas; Tiemann, Klaus; Schnackenburg, Bernhard; Crelier, Gerard R; Heindel, Walter; Maintz, David

    2012-09-01

    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. 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. 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). 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. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  15. Coronary artery aneurysm after stent implantation: acute and long-term results after percutaneous treatment with a stent graft.

    Science.gov (United States)

    Rubartelli, Paolo; Terzi, Giacomo; Borgo, Lorenzo; Giachero, Corinna

    2002-03-01

    A patient with unstable angina was treated with elective Palmaz-Schatz stent implantation on a focal stenosis of the left circumflex artery. One year later, a large (13 mm in diameter) coronary artery aneurysm was diagnosed at angiography in the stented site. Intravascular ultrasound examination confirmed the presence of a true aneurysm located at the proximal end of the stent. The aneurysm was successfully treated with a Jostent Graft (Jomed Implantate) consisting of two slotted tube stainless steel stents supporting a polytetrafluoroethylene tube. The stent graft was implanted under intravascular ultrasound guidance. The 18-month angiographic follow-up showed good patency of the stent graft and complete exclusion of the aneurysm.

  16. XIENCE V everolimus-eluting coronary stent system: a novel second generation drug-eluting stent

    NARCIS (Netherlands)

    Beijk, Marcel A. M.; Piek, Jon J.

    2007-01-01

    Drug-eluting stents (DES) have been shown to be safe and significantly reduce clinical events and angiographic restenosis in the percutaneous treatment of coronary artery disease. Currently, three DES have been approved in Europe and Northern America: the sirolimus-eluting stent (SES), the

  17. Nitinol Esophageal Stents: New Designs and Clinical Indications

    International Nuclear Information System (INIS)

    Strecker, Ernst-Peter; Boos, Irene; Vetter, Sylvia; Strohm, Michael; Domschke, Sigurd

    1996-01-01

    Purpose: To evaluate the clinical use of covered and noncovered, knitted nitinol stents in patients presenting new stent indications. Methods: Self-expandable, knitted nitinol stents were implanted in four patients for treatment of dysphagia. In two patients who had malignant strictures and had esophago-respiratory fistulae and in one patient with an esophagocutaneous fistula, polytetrafluoroethylene (PTFE)-covered stents were implanted. One patient received a noncovered stent, but a retrograde approach through a percutaneous endoscopic gastrostomy (PEG) fistula had to be chosen for recanalization of an esophageal occlusion. Two patients received stents for treatment of benign strictures. Results: Recanalization of the stricture and stent implantation were performed under fluoroscopic control without any procedure-related morbidity or mortality. Dysphagia improved in all patients and the esophageal fistulae could be sealed off by covered stents. During a maximum follow-up of 18 months, there was no stent migration or esophageal perforation. Complications observed were stent stenosis due to food impaction (1/4) and benign stent stenosis (2/2). Most complications could be treated by the interventional radiologist. Conclusion: Self-expandable, covered Nitinol stents provide an option for the treatment of dysphagia combined with esophageal fistulae. In combination with interventional radiology techniques, even complex strictures are accessible. For benign strictures, the value of stent treatment has not yet been proven

  18. Risk Factors for Migration, Fracture, and Dislocation of Pancreatic Stents

    Directory of Open Access Journals (Sweden)

    Yoshiaki Kawaguchi

    2015-01-01

    Full Text Available Aim. To analyze the risk factors for pancreatic stent migration, dislocation, and fracture in chronic pancreatitis patients with pancreatic strictures. Materials and Methods. Endoscopic stent placements (total 386 times were performed in 99 chronic pancreatitis patients with pancreatic duct stenosis at our institution between April 2006 and June 2014. We retrospectively examined the frequency of stent migration, dislocation, and fracture and analyzed the patient factors and stent factors. We also investigated the retrieval methods for migrated and fractured stents and their success rates. Results. The frequencies of stent migration, dislocation, and fracture were 1.5% (5/396, 0.8% (3/396, and 1.2% (4/396, respectively. No significant differences in the rates of migration, dislocation, or fracture were noted on the patient factors (etiology, cases undergoing endoscopic pancreatic sphincterotomy, location of pancreatic duct stenosis, existence of pancreatic stone, and approach from the main or minor papilla and stent factors (duration of stent placement, numbers of stent placements, stent shape, diameter, and length. Stent retrieval was successful in all cases of migration. In cases of fractured stents, retrieval was successful in 2 of 4 cases. Conclusion. Stent migration, fracture, and dislocation are relatively rare, but possible complications. A good understanding of retrieval techniques is necessary.

  19. New expandable metallic stents: An experimental study in vessels of dogs

    International Nuclear Information System (INIS)

    Song, Ho Young; Lee, Jung Min; Chung, Jin Young; Chung, Gyung Ho; Kim, Bog Yi; Kuh, Ja Houng

    1992-01-01

    Three-types of expandable metallic stents were constructed to evaluate the differences between the stents: one, formed in a cylindrical zigzag pattern wth stainless steel wire (Gianturco stent), another, made by coating the Gianturco stent with silicone rubber (Silicone stent), the third, made by coating the Gianturco stent with 24 carat gold (Gold stent) for tissue acceptance. A total of 69 stents (each 23 stents of Gianturco, Silicone, and Gold stents) of 8-12 mm in diameter and 20 mm long were placed into normal abdominal aorta, inferior vena cava and lilac artery of nine adults dogs for 2 weeks to 11 months. It was more difficult to introduce Silicone stent into an introducing sheath than Gianturco or Gold stent due to the thickness of silicone rubber. Four Gianturco stents and three Silicone stents showed migration but Gold stent did not. Luminal narrowing or occlusion was noted in 3 Silicone stents. In 2 Gianturco stents, and in 1 Gold stent. Neointimal proliferation over the stent wires was more rapid and even in Gold stent than Silicone or Gianturco stent. Although further study is needed, Gold stent seems to be better than Gianturco or Silicone stent as an endovascular graft material

  20. New expandable metallic stents: An experimental study in vessels of dogs

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ho Young; Lee, Jung Min; Chung, Jin Young; Chung, Gyung Ho; Kim, Bog Yi; Kuh, Ja Houng [Chunbuk National University Medical School, Chunju (Korea, Republic of)

    1992-07-15

    Three-types of expandable metallic stents were constructed to evaluate the differences between the stents: one, formed in a cylindrical zigzag pattern wth stainless steel wire (Gianturco stent), another, made by coating the Gianturco stent with silicone rubber (Silicone stent), the third, made by coating the Gianturco stent with 24 carat gold (Gold stent) for tissue acceptance. A total of 69 stents (each 23 stents of Gianturco, Silicone, and Gold stents) of 8-12 mm in diameter and 20 mm long were placed into normal abdominal aorta, inferior vena cava and lilac artery of nine adults dogs for 2 weeks to 11 months. It was more difficult to introduce Silicone stent into an introducing sheath than Gianturco or Gold stent due to the thickness of silicone rubber. Four Gianturco stents and three Silicone stents showed migration but Gold stent did not. Luminal narrowing or occlusion was noted in 3 Silicone stents. In 2 Gianturco stents, and in 1 Gold stent. Neointimal proliferation over the stent wires was more rapid and even in Gold stent than Silicone or Gianturco stent. Although further study is needed, Gold stent seems to be better than Gianturco or Silicone stent as an endovascular graft material.

  1. Intravascular imaging comparison of two metallic limus-eluting stents abluminally coated with biodegradable polymers: IVUS and OCT results of the DESTINY trial.

    Science.gov (United States)

    Costa, J Ribamar; Chamié, Daniel; Abizaid, Alexandre A C; Ribeiro, Expedito; Meireles, George C; Prudente, Maurício; Campos, Carlos A; Castro, Juliana P; Costa, Ricardo; Lemos, Pedro A

    2017-02-01

    We sought to compare, by means of IVUS and OCT imaging, the performance of a novel sirolimus-eluting drug-eluting stent (DES) with biodegradable polymer (Inspiron™) to the Biomatrix™ DES. From the DESTINY trial, a total of 70 randomized patients (2:1) were enrolled in the IVUS substudy (Inspiron™, n = 46; Biomatrix™: n = 20) while 25 patients were evaluated with OCT (Inspiron™, n = 19; Biomatrix™: n = 06) at 9-month follow-up. The main endpoints were % of neointimal tissue obstruction (IVUS) and neointimal stut coverage (OCT) at 9 months. Patients treated with both DES had very little NIH formation at 9 months either by IVUS (% of NIH obstruction of 4.9 ± 4.1 % with Inspiron™ vs. 2.7 ± 2.9 % with Biomatrix™, p = 0.03) or by OCT (neointimal thickness of 144.2 ± 72.5 µm Inspiron™ vs. 115.0 ± 53.9 µm with Biomatrix™, p = 0.45). Regarding OCT strut-level assessment, again both devices showed excellent 9-month performance, with high rates of strut coverage (99.49 ± 1.01 % with Inspiron™ vs. 97.62 ± 2.21 % with Biomatrix™, p < 0.001) and very rare malapposition (0.29 ± 1.06 % with Inspiron™ vs. 0.53 ± 0.82 % with Biomatrix™, p = 0.44). Patients with any uncovered struts were more frequently identified in the Biomatrix™ group (9.78 ± 7.13 vs. 2.29 ± 3.91 %, p < 0.001). In the present study, midterm IVUS and OCT evaluations showed that both new generation DES with biodegradable polymer were effective in terms of suppressing excessive neointimal response, with very high rates of apposed and covered struts, suggesting a consistent and benign healing pattern.

  2. 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......-coated sirolimus-eluting stent in a population-based setting....

  3. Comparison of Single Ti6Al4V Struts Made Using Selective Laser Melting and Electron Beam Melting Subject to Part Orientation

    Directory of Open Access Journals (Sweden)

    Volker Weißmann

    2017-03-01

    Full Text Available The use of additive manufacturing technologies to produce lightweight or functional structures is widespread. Especially Ti6Al4V plays an important role in this development field and parts are manufactured and analyzed with the aim to characterize the mechanical properties of open-porous structures and to generate scaffolds with properties specific to their intended application. An SLM and an EBM process were used respectively to fabricate the Ti6Al4V single struts. For mechanical characterization, uniaxial compression tests and hardness measurements were conducted. Furthermore, the struts were manufactured in different orientations for the determination of the mechanical properties. Roughness measurements and a microscopic characterization of the struts were also carried out. Some parts were characterized following heat treatment (hot isostatic pressing. A functional correlation was found between the compressive strength and the slenderness ratio (λ as well as the equivalent diameter (d and the height (L of EBM and SLM parts. Hardness investigations revealed considerable differences related to the microstructure. An influence of heat treatment as well as of orientation could be determined. In this work, we demonstrate the influence of the fabrication quality of single struts, the roughness and the microstructure on mechanical properties as a function of orientation.

  4. Stent-in-Stent Technique for the Treatment of Proximal Bronchial Restenosis after Insertion of Metallic Stents: A Report of Two Cases

    Directory of Open Access Journals (Sweden)

    Benjamin Bondue

    2016-01-01

    Full Text Available Endoscopic treatment of a bronchial restenosis previously treated by insertion of a partially covered self-expandable metallic stent (SEMS can be difficult. Classically, after recanalization of the bronchus, the stent is removed and replaced by a more adapted one. We report on two cases of proximal bronchial restenosis treated by insertion of an additional stent inside the lumen of the previously inserted stent using the stent-in-stent (SIS technique. The indications for the initial stent were malignancy in Patient 1 and posttransplant bronchial stenosis in Patient 2. Restenosis occurred at the proximal end of the stent within months in both cases. Stent removal and insertion of a new stent were considered, but this option was discarded because of an excessive risk of bronchial perforation and preference towards an alternative approach. In both cases, a second customized SEMS was placed using the SIS technique after ablation of the proximal end stenosis of the stent by argon plasma coagulation and/or dilation with a balloon. Recanalization of the bronchus was achieved in both cases without complications. The SIS technique is a valuable alternative to removal of SEMS in case of proximal bronchial restenosis.

  5. Study on the application of big cup membranate stent on restenosis after stenting for carcinoma of esophago cardia

    International Nuclear Information System (INIS)

    Wang Xiuping; Yao Zhongqiang; Liu Jian; Zhang Yan

    2007-01-01

    Objective: To evaluate the clinical value of self-designed big cup membranate stent on restenosis after stenting for carcinoma of esophago-cardia. Methods: 12 cases of restenosis after stenting for carcinoma of esophago-cardia were involved in the study. Self-designed big cup membranate stent made by Nanjing Weichuang Company (the length of the cup was 3.5 cm)was placed into the constricted stent under guidance of fluoroscopy. Clinical effect, restenosis, and complications were observed during followed up. Results: All the 12 cases of big cup membranat stent placement went along smoothly without indigitation of the cup of the stent. Follow-up of 1.5-8 months showed that 2 cases developed severe restenosis on the big cup of the stem, resulting in third grade difficult deglutition. Among them, one occurred 1 month after stenting, caused by hyperplasia of large amount of granulation tissue; another occurred 6 months after stenting, caused by growth of tumor tissue. 3 cases developed mild to moderate restenosis, 2.3-7 months (mean: 4.6 months) after stenting, with result of first grade difficult deglutition. The remaining 7 cases (mean 5.6 months follow-up) did not have difficulty during deglutition. Conclusions: Application of big cup membranate stent on restenosis after stenting for carcinoma of esophago-cardia can effectively prevent the stent from moving downwards and thus lower down the rate of restenosis, and postpone the occurrence of restenosis. (authors)

  6. [Cost-effectiveness trial of self-expandable metal stents and plastic biliary stents in malignant biliary obstruction].

    Science.gov (United States)

    Daróczi, Tímea; Bor, Renáta; Fábián, Anna; Szabó, Ella; Farkas, Klaudia; Bálint, Anita; Czakó, László; Rutka, Mariann; Szűcs, Mónika; Milassin, Ágnes; Molnár, Tamás; Szepes, Zoltán

    2016-02-14

    Self-expandable metal and plastic stents can be applied in the palliative endoscopic treatment of patients with unresectable malignant biliary obstruction. The use of metal stentsis recommended if the patient's life expectancy is more than four months. To compare the therapeutic efficacy and cost-effectiveness of metal and plastic stents in the treatment of malignant biliary obstruction. The authors retrospectively enrolled patients who received metal (37 patients) or plastic stent (37 patients). The complication rate, stent patency and cumulative cost of treatment were assessed in the two groups. The complication rate of metal stents was lower (37.84% vs. 56.76%), but the stent patency was higher compared with plastic stents (19.11 vs. 8.29 weeks; p = 0.0041). In the plastic stent group the frequency of hospitalization of patients in context with stent complications (1.18 vs. 2.32; p = 0.05) and the necessity of reintervention for stent dysfunction (17 vs. 27; p = 0.033) were substantially higher. In this group multiple stent implantation raised the stent patency from 7.68 to 10.75 weeks. There was no difference in the total cost of treatment of malignant biliary obstruction between the two groups (p = 0.848). Considering the cost of treatment and the burden of patients the authors recommend self-expandable metal sten timplantation if the life expectancy of patients is more than two months. In short survival cases multiple plastic stent implantation is recommended.

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

    LENUS (Irish Health Repository)

    Ali, Mohammed

    2011-08-01

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

  8. Forgotten ureteral stents: Risk factors, complications and management

    African Journals Online (AJOL)

    A.Y. Abdelaziz

    2018-02-07

    Feb 7, 2018 ... Preoperative non-contrast spiral CT abdomen and pelvis showed encrustations on the stent in 23.5% of patients ... Despite their advantages, ureteral stents are not without possible morbidity. ..... A model to quantify encrusta-.

  9. Successful Expansion of an Underexpanded Stent by Rotational Atherectomy

    Science.gov (United States)

    Vales, Lori; Coppola, John; Kwan, Tak

    2013-01-01

    The current routine use of intracoronary stents in percutaneous coronary intervention (PCI) has significantly reduced rates of restenosis, compared with balloon angioplasty alone. On the contrary, small post-stenting luminal dimensions due to undilatable, heavily calcified plaques have repeatedly been shown to significantly increase the rates of in-stent restenosis. Rotational atherectomy of lesions is an alternative method to facilitate PCI and prevent underexpansion of stents, when balloon angioplasty fails to successfully dilate a lesion. Stentablation, using rotational atherectomy to expand underexpanded stents deployed in heavily calcified plaques, has also been reported. We report a case via the transradial approach of rotational-atherectomy–facilitated PCI of in-stent restenosis of a severely underexpanded stent due to a heavily calcified plaque. We review the literature and suggest rotational atherectomy may have a role in treating a refractory, severely underexpanded stent caused by a heavily calcified plaque through various proposed mechanisms. PMID:24436587

  10. Hemodynamic comparison of stent configurations used for aortoiliac occlusive disease

    NARCIS (Netherlands)

    Groot Jebbink, Erik; Mathai, Varghese; Boersen, Johannes Thomas; Sun, Chao; Slump, Cornelis H.; Goverde, Peter C.J.M.; Versluis, Michel; Reijnen, Michel M.P.J.

    Background Endovascular treatment of aortoiliac occlusive disease entails the use of multiple stents to reconstruct the aortic bifurcation. Different configurations have been applied and geometric variations exist, as quantified in previous work. Other studies concluded that specific stent geometry

  11. Technological Advances in Stent Therapies: a Year in Review.

    Science.gov (United States)

    Raffoul, Jad; Nasir, Ammar; Klein, Andrew J P

    2018-04-07

    Stent technology has rapidly evolved since the first stainless steel bare metal stents with substantial developments in scaffolding, polymer, drug choice, drug delivery, and elution mechanisms. Most recently, there has been the evolution of bioabsorbable vascular scaffolds, potentially eliminating the need for long-term foreign object retention. These rapid developments have led to an ever-expanding selection of new stents, making the choice of which to use in which patient challenging. Operators must balance potential short- and long-term clinical ramifications, namely stent thrombosis, in-stent restenosis, target lesion revascularization, and target lesion failure. In this review, we hope to provide insight for interventional cardiologists on the details of stent technology and how this impacts outcomes, stent selection, and duration of dual-antiplatelet therapy duration post drug-eluting stent implantation.

  12. Three-dimensional strutted graphene grown by substrate-free sugar blowing for high-power-density supercapacitors

    Science.gov (United States)

    Wang, Xuebin; Zhang, Yuanjian; Zhi, Chunyi; Wang, Xi; Tang, Daiming; Xu, Yibin; Weng, Qunhong; Jiang, Xiangfen; Mitome, Masanori; Golberg, Dmitri; Bando, Yoshio

    2013-12-01

    Three-dimensional graphene architectures in the macroworld can in principle maintain all the extraordinary nanoscale properties of individual graphene flakes. However, current 3D graphene products suffer from poor electrical conductivity, low surface area and insufficient mechanical strength/elasticity; the interconnected self-supported reproducible 3D graphenes remain unavailable. Here we report a sugar-blowing approach based on a polymeric predecessor to synthesize a 3D graphene bubble network. The bubble network consists of mono- or few-layered graphitic membranes that are tightly glued, rigidly fixed and spatially scaffolded by micrometre-scale graphitic struts. Such a topological configuration provides intimate structural interconnectivities, freeway for electron/phonon transports, huge accessible surface area, as well as robust mechanical properties. The graphene network thus overcomes the drawbacks of presently available 3D graphene products and opens up a wide horizon for diverse practical usages, for example, high-power high-energy electrochemical capacitors, as highlighted in this work.

  13. Numerical analysis and design optimization of supersonic after-burning with strut fuel injectors for scramjet engines

    Science.gov (United States)

    Candon, M. J.; Ogawa, H.

    2018-06-01

    Scramjets are a class of hypersonic airbreathing engine that offer promise for economical, reliable and high-speed access-to-space and atmospheric transport. The expanding flow in the scramjet nozzle comprises of unburned hydrogen. An after-burning scheme can be used to effectively utilize the remaining hydrogen by supplying additional oxygen into the nozzle, aiming to augment the thrust. This paper presents the results of a single-objective design optimization for a strut fuel injection scheme considering four design variables with the objective of maximizing thrust augmentation. Thrust is found to be augmented significantly owing to a combination of contributions from aerodynamic and combustion effects. Further understanding and physical insights have been gained by performing variance-based global sensitivity analysis, scrutinizing the nozzle flowfields, analyzing the distributions and contributions of the forces acting on the nozzle wall, and examining the combustion efficiency.

  14. Heat transfer in a compact tubular heat exchanger with application to the engine struts of the national aerospace plane

    International Nuclear Information System (INIS)

    Olsen, D.A.

    1991-01-01

    The authors constructed an apparatus to measure heat transfer coefficients in compact heat exchangers which are candidate cooling jackets for the engine struts of the National Aerospace Plane. This paper reports measurements on a tube specimen heat exchanger. The heat exchanger consisted of 20 nickel tubes (2 mm OD, 1 mm ID, 15.2 cm heated length), brazed to a 3 mm thick nickel plate. The tubes lay parallel to one another, 3.8 mm on-center separation. The heat exchanger was heated on one side in a radiative furnace at heat fluxes of 3.4 to 54 W/cm 2 over a normal area of 7.8 cm by 15.2 cm. The coolant fluid was helium gas at Reynolds numbers of 3000 to 35 000 and 3.50 MPa pressure. For high heat flux and low

  15. Metallic Stents for Tracheobronchial Pathology Treatment

    International Nuclear Information System (INIS)

    Serrano, Carolina; Laborda, Alicia; Lozano, Juan M.; Caballero, Hugo; Sebastián, Antonio; Lopera, Jorge; Gregorio, Miguel Ángel de

    2013-01-01

    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

  16. Metallic stents for tracheobronchial pathology treatment.

    Science.gov (United States)

    Serrano, Carolina; Laborda, Alicia; Lozano, Juan M; Caballero, Hugo; Sebastián, Antonio; Lopera, Jorge; de Gregorio, Miguel Ángel

    2013-12-01

    To present the 7-year experience of the treatment of benign and malignant tracheobronchial stenoses using metallic stents. 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. 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. 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.

  17. 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.

  18. Broken Esophageal Stent Successfully Treated by Interventional Radiology Technique

    International Nuclear Information System (INIS)

    Zelenak, Kamil; Mistuna, Dusan; Lucan, Jaroslav; Polacek, Hubert

    2010-01-01

    Esophageal stent fractures occur quite rarely. A 61-year-old male patient was previously treated for rupture of benign stenosis, occurring after dilatation, by implanting an esophageal stent. However, a year after implantation, the patient suffered from dysphagia caused by the broken esophageal stent. He was treated with the interventional radiology technique, whereby a second implantation of the esophageal stent was carried out quite successfully.

  19. Risk of stent thrombosis among bare-metal stents, first-generation drug-eluting stents, and second-generation drug-eluting stents: results from a registry of 18,334 patients.

    Science.gov (United States)

    Tada, Tomohisa; Byrne, Robert A; Simunovic, Iva; King, Lamin A; Cassese, Salvatore; Joner, Michael; Fusaro, Massimiliano; Schneider, Simon; Schulz, Stefanie; Ibrahim, Tareq; Ott, Ilka; Massberg, Steffen; Laugwitz, Karl-Ludwig; Kastrati, Adnan

    2013-12-01

    This study sought to compare the risk of stent thrombosis among patients treated with bare-metal stents (BMS), first-generation drug-eluting stents (G1-DES), and second-generation drug-eluting stents (G2-DES) for a period of 3 years. In patients undergoing coronary stenting, there is a scarcity of long-term follow-up data on cohorts large enough to compare rates of stent thrombosis across the stent generations. A total of 18,334 patients undergoing successful coronary stent implantation from 1998 to 2011 at 2 centers in Munich, Germany, were included in this study. Patients were stratified into 3 groups according to treatment with BMS, G1-DES, and G2-DES. The cumulative incidence of definite stent thrombosis at 3 years was 1.5% with BMS, 2.2% with G1-DES, and 1.0% with G2-DES. On multivariate analysis, G1-DES compared with BMS showed a significantly higher risk of stent thrombosis (odds ratio [OR]: 2.05; 95% confidence interval [CI]: 1.47 to 2.86; p stent thrombosis compared with BMS (OR: 0.82; 95% CI: 0.56 to 1.19; p = 0.30). Beyond 1 year, the risk of stent thrombosis was significantly increased with G1-DES compared with BMS (OR: 4.72; 95% CI: 2.01 to 11.1; p stenting, compared with BMS, there was a significant excess risk of stent thrombosis at 3 years with G1-DES, driven by an increased risk of stent thrombosis events beyond 1 year. G2-DES were associated with a similar risk of stent thrombosis compared with BMS. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  20. Migrated esophageal stent posing a challenge for ventilation

    Directory of Open Access Journals (Sweden)

    Nita D'souza

    2017-01-01

    Full Text Available Self-expandable esophageal stents are being commonly used for palliative treatment in advanced esophageal cancer patients to relieve dysphagia, prevent tracheoesophageal fistula, and facilitate symptomatic betterment. The modern covered stents reduce the ingrowth of the tumor but have seen an increase in the incidence of stent migrations. We report a rather complicated presentation of an esophageal stent for esophageal dilatation and a challenging management of a difficult tracheostomy.

  1. Strut fracture with Björk-Shiley 70 degrees convexo-concave valve. An international multi-institutional follow-up study.

    Science.gov (United States)

    Ericsson, A; Lindblom, D; Semb, G; Huysmans, H A; Thulin, L I; Scully, H E; Bennett, J G; Ostermeyer, J; Grunkemeier, G L

    1992-01-01

    Between 1980 and 1983, 831 Björk-Shiley 70 degrees convexo-concave prosthetic heart valves were implanted at five institutions in Sweden, Germany. The Netherlands, and Canada. As of January 1991, there were 34 outlet strut fractures occurring from 0.2 to 10.1 years (median = 4.6 years) after implantation. In addition, there were 28 sudden, unexplained deaths. The mortality after strut fracture was 84%. The mortality after emergency valve replacement for strut fracture was 50%. The 10-year actuarial fracture rate (standard error) was 10.5 (2.4)% for large (29-33 mm) valves vs. 3.3 (1.2)% for 21-27 mm valves (P less than 0.001). Within valve size groups, fracture rates for aortic and mitral valves were similar. Cox regression analysis found only valve size to be significantly associated with strut fracture. There is a further subgrouping of the valves according to the manufacturer: group I are the earlier large 29-33 mm) valves; group II are the later large valves; group III are the small size (21-27 mm) valves. The risk of strut fracture was highest in group I (12.3% at 10 years) with an approximatively constant hazard (1.4% per year). A comparison was made with a statistical model incorporating all cases reported to the manufacturer. This model estimates fracture rates approximately 63%-73% of those found in the present study. These findings lead us to recommend that group I patients should be considered for elective reoperation on an individual basis, giving careful attention to risk factors and contraindications.

  2. Nasolacrimal Stenting: Toward Improving Outcomes with a Simple Modification of the Song Stent

    International Nuclear Information System (INIS)

    Lanciego, Carlos; Miguel, Silvia De; Padilla, Manuel; Perea, Miguel; Rodriguez-Merlo, Rufo; Garcia-Garcia, Lorenzo

    2006-01-01

    The purpose of this study was to evaluate, in a prospective, single-center study, the effectiveness of Song's polyurethane stents, modified 'in-house,' in the percutaneous management of epiphora. Patients (n = 170; age range 18-83, mean = 64; 50 male, 120 female) with severe epiphora had the modified stents inserted (183 eyes/195 stents) to treat unilateral/bilateral and complete/partial obstruction of the nasolacrimal system. The etiology of the obstruction was idiopathic in 119 cases (61%) and chronic dacryocystitis in 76 (39%). The set designed by Song was used in all patients but modified by us such that the extreme end is cone-shaped. The original technique was slightly modified by us and the procedure was conducted on an outpatient basis. The initial technical success rate of stent placement was 97%. Resolution of epiphora was complete in 180 eyes and partial in 3. On follow-up (mean = 18 months; range: 2 days to 24 months), 165 of 195 stents (85%) remained patent. Primary patency rates at follow-up were 86%, 84%, 84%, and 79% in the first 6 months, second and third 6 months, and the present (24 months), respectively. Stents became obstructed in 30 patients, but all but 2 were easily withdrawn and 20 of these patients remained asymptomatic for a mean of 14 months (secondary patency of 67%). Following stent removal, the withdrawn stent was replaced with a new stent in the same intervention on 14 occasions. In another six cases, patency was re-established without the need of a second stent. The procedure is simple and safe, both in stent insertion as well as in mechanical de-blocking and withdrawal when occluded. Success was >80 % in the short term (1-year follow-up). Stenting failure does not preclude other treatment because with the modification that we had introduced, the extreme end of the stent becomes more accessible to mechanical de-blocking, withdrawal, and relocation. The levels of primary and secondary patencies are promising and warrant more

  3. Temporary stenting and retrieval of the self-expandable, intracranial stent in acute middle cerebral artery occlusion

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Sang Hyun; Chung, Tae-Sub [Yonsei University College of Medicine, Department of Radiology, Gangnam Severance Hospital, Seoul (Korea); Lee, Kyung-Yul [Yonsei University College of Medicine, Department of Neurology, Gangnam Severance Hospital, Seoul (Korea); Hong, Chang Ki; Kim, Chang-Hyun [Yonsei University College of Medicine, Department of Neurosurgery, Gangnam Severance Hospital, Seoul (Korea); Kim, Byung Moon; Kim, Dong Ik [Yonsei University College of Medicine, Department of Radiology, Seoul (Korea)

    2009-08-15

    We describe our experience in which a retrievable Enterprise stent was used as a temporary recanalization and embolectomy device in an acute middle cerebral artery (MCA) occlusion after urgent stenting for ipsilateral carotid artery stenosis. (orig.)

  4. Percutaneous transhepatic self-expanding metal stents for palliation ...

    African Journals Online (AJOL)

    Stent occlusion occurred in 4 patients (8%) within a week as result of stent migration (n=3) or presumed biliary sludge (n=1); 2 (4%) stents occluded between 7 days and 1 month. Four patients (8%) died during hospital admission due to pre-existing biliary sepsis (n=3) and pneumonia (n=1). Nine patients developed ...

  5. 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

  6. Covered Balloon-Expanding Stents in Airway Stenosis.

    Science.gov (United States)

    Majid, Adnan; Kheir, Fayez; Chung, Jey; Alape, Daniel; Husta, Bryan; Oh, Scott; Folch, Erik

    2017-04-01

    The balloon-expanding stents are widely available but rarely described for use within the tracheobronchial tree. This report describes our experience with these stents in airway stenosis particularly as a lobar salvage therapy. This was a retrospective review of all records in which the balloon-expanding stents were used at a tertiary medical center. Ages, sex, location of stenosis, etiology of stenosis, stent size, duration of stent placement and associated interventions for airway stenosis were recorded. Patient's self-reported respiratory symptoms, dyspnea scale, and radiographic imaging at baseline and after stent placement were also reported. Twenty-one Atrium iCAST stents were inserted in 18 patients with malignant and benign airway disease. The median age was 69.5 years (interquartile range, 53.5 to 74). Most stents (n=20, 95%) were deployed in the lobar airways. There was a significant improvement in the modified Medical Research Council dyspnea scale from median of 3 to 2 (Pstent placement was achieved in 15 patients (83%). No deaths were related to airway stenting complications. Adverse events related to stents included migration (n=2, 9.5%), granulation tissue formation (n=2, 9.5%) and mucus plugging (n=1, 4.8%). Lobar stenting with balloon-expanding metallic stents appears feasible, safe and improves symptoms as well as radiographic atelectasis in patients with lobar airway stenosis in this small case series. Larger studies are needed to confirm this observation and to address long-term safety.

  7. A scanning electron microscopic study of biliary stent materials

    NARCIS (Netherlands)

    van Berkel, A. M.; van Marle, J.; van Veen, H.; Groen, A. K.; Huibregtse, K.

    2000-01-01

    Clogging of biliary stents remains an important problem. In vitro studies have shown less sludge formation in Teflon stents. Recently, clinical studies with Teflon stents have produced contradictory results. The aim of this study was to investigate whether the surface properties of the

  8. New techniques for stenting severely strictured or occluded ureters

    Energy Technology Data Exchange (ETDEWEB)

    Mygind, T; Dorph, S; Nielsen, H; Nielsen, L

    1985-11-01

    Percutaneous stenting of the severely strictured ureter is facilitated by catheterization through a rigid curved tube leading through the kidney. Alternatively, bidirectional traction tensioning of a guide wire pulled through the entire urinary tract permits antegrade dilatation and stent drainage. Complete occlusion near the ureteric orifice may be bypassed by transureteral puncture of the bladder followed by stent insertion.

  9. Mechanical Behavior of Fully Expanded Commercially Available Endovascular Coronary Stents

    OpenAIRE

    Tambaca, Josip; Canic, Suncica; Kosor, Mate; Fish, R. David; Paniagua, David

    2011-01-01

    The mechanical behavior of endovascular coronary stents influences their therapeutic efficacy. Through computational studies, researchers can analyze device performance and improve designs. We developed a 1-dimensional finite element method, net-based algorithm and used it to analyze the effects of radial loading and bending in commercially available stents. Our computational study included designs modeled on the Express, Cypher, Xience, and Palmaz stents.

  10. Malignant biliary obstruction: percutaneous use of self-expandable stents

    NARCIS (Netherlands)

    Laméris, J. S.; Stoker, J.; Nijs, H. G.; Zonderland, H. M.; Terpstra, O. T.; van Blankenstein, M.; Schütte, H. E.

    1991-01-01

    A total of 83 self-expandable metallic stents were placed percutaneously in 69 patients for palliation of malignant biliary obstruction. Stent diameter was 1 cm; length, 3.5-10.5 cm. Of the 41 patients with common bile duct obstruction, 27 died 0.2-12 months (median, 3.2 months) after stent

  11. Welded tracheal stent removal in a child under cardiopulmonary bypass.

    Science.gov (United States)

    Kao, S C; Chang, W K; Pong, M W; Cheng, K W; Chan, K H; Tsai, S K

    2003-08-01

    Metallic tracheal stents have been used in the treatment of paediatric tracheomalacia for more than a decade. We describe a case in which critical airway obstruction occurred during removal of a welded tracheal stent using a rigid bronchoscope under general anaesthesia. Life-saving cardiopulmonary bypass was instituted urgently, and the welded stent was then removed successfully by directly opening the trachea.

  12. Role of Montgomery T-tube stent for laryngotracheal stenosis.

    Science.gov (United States)

    Prasanna Kumar, Saravanam; Ravikumar, Arunachalam; Senthil, Kannan; Somu, Lakshman; Nazrin, Mohd Ismail

    2014-04-01

    To identify the indications, complications and outcome of patients of LTS managed with Montgomery T-tube stenting and review the current literature about the role of stenting in LTS. Retrospective chart reviews of 39 patients of laryngotracheal stenosis managed by T-tube stenting for temporary or definitive treatment during the period 2004-2011 were considered. The data on indications for stenting, type of stent, problems/complications of stenting, duration of stenting, additional intervention and outcome of management were collected, tabulated and analyzed. Of the 51 cases of laryngotracheal stenosis 39 patients were treated by Montgomery T-tube stenting. There was no mortality associated with the procedure or stenting. 82% of the patients were successfully decannulated. The problems and complications encountered were crusting within the tube in 44% and granulation at the subglottis in 33%. Two patients had complication due to T-tube itself: One patient developed tracheomalacia and the other had stenosis at both ends of the T-tube. Stenting still has a role in management of inoperable or in some deadlock situations where resection anastomosis is not feasible. It is easier to introduce the stent and to maintain it. Complications are minor and can be managed easily. It is safe for long term use. We emphasize that the treating surgeon needs to use prudence while treating stenosis using stents. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  13. Invention of a nasolacrimal stent retrieval hook

    International Nuclear Information System (INIS)

    Kim, Tae Hyung; Kim, Yeong Kyun; Park, Sang Soo; Song, Ho Young

    1997-01-01

    To evaluate the clinical usefulness of a nasolacrimal stent retrieval hook The retrieval hook consisted of two parts, a hook and pusher. The head of the hook part was made of 0.7mm stainless steel wire and was question mark-shaped, while the body of this part was constructed by soldering together four stainless steel pipes ranging in thickness from 1.25 to 3.5mm, serially. The pusher part was made of two plastic tubes and was designed in such a way that the hook grasped the stent tightly. The device was used to remove 46 stents in 40 patients, and tested for 1) average number of trials;2) success rate;and 3) average time of the procedure. The average number of trials, success rate, and average time taken to remove the stent was 4.7, 91%, and 1.8 minutes, respectively. In the removal of nasolacrimal stents, the retrieval hook was easy to use, useful and effective

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

    Science.gov (United States)

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

    2016-03-01

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

  15. Anchoring barbs and balloon expandable stents: what is the risk of perforation and failed stent deployment?

    Science.gov (United States)

    Bown, M J; Harrison, G J; How, T V; Brennan, J A; Fisher, R K; Vallabhaneni, S R; McWilliams, R G

    2012-09-01

    Balloon expandable stents may on occasion be deployed in close proximity to the anchoring barbs of endovascular grafts. The aim of this study was to determine the risk and effect of balloon perforation by anchoring barbs and to assess whether these risks are different if the balloon is protected by a covered stent mounted upon it. A bench-top model was developed to mimic the penetration of anchoring barbs into the lumen of medium sized blood vessels. The model allowed variation of angle and depth of vessel penetration. Both bare balloons and those with covered stents mounted upon them were tested in the model to determine whether there was a risk of perforation and which factors increased or decreased this risk. All combinations of barb angle and depth caused balloon perforation but this was most marked when the barb was placed perpendicular to the long axis of the balloon. When the deployment of covered stents was attempted balloon perforation occurred in some cases but full stent deployment was achieved in all cases where the perforation was in the portion of the balloon covered by the stent. The only situation in which stent deployment failed was where the barb was intentionally placed in the uncovered portion of the balloon. This resulted in only partial deployment of the stent. Balloon rupture is a distinct possibility when deploying balloon-expandable stents in close proximity to anchoring barbs. Care should be taken in this circumstance to ensure that the barb is well away from the uncovered portion of the balloon. Copyright © 2012 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

  16. Intraluminal Radioactive Stent Compared with Covered Stent Alone for the Treatment of Malignant Esophageal Stricture

    International Nuclear Information System (INIS)

    Wang Zhongmin; Huang Xunbo; Cao Jun; Huang Gang; Chen Kemin; LIu Yu; Liu Fenju

    2012-01-01

    Objective: This study was designed to compare the clinical effectiveness of intraluminal radioactive stent loaded with iodine-125 seeds implantation versus covered stent alone insertion in patients with malignant esophageal stricture. Methods: We studied two groups of patients with malignant esophageal stricture. Group A comprised 28 patients (19 men and 9 women) who underwent intraluminal radioactive stent loaded with iodine-125 seeds implantation and were followed prospectively. Group B comprised 30 patients (18 men and 12 women) who had previously received covered stent alone insertion; these patients were evaluated retrospectively. There was no crossover between the two groups during follow-up. Informed consent was obtained from each patient, and our institutional review board approved the study. The dysphagia score, overall survival rates, complication rates, and reintervention rates were compared in the two groups. Results: There were no significant differences between the two groups in terms of baseline characteristics. Stent placement was technically successful and well tolerated in all patients. The dysphagia score was improved in both groups after stent placement. The median survival was significantly longer in group A than in group B: 11 versus 4.9 months, respectively (P < 0.001). The complications of chest pain, esophageal reflux, and stent migration was more frequent in group B, but this difference did not reach statistical significance. There was no statistical difference in reintervention between two groups. Conclusions: Intraluminal radioactive stent loaded with iodine-125 seeds implantation was a feasible and practical management in treating malignant esophageal stricture and was superior to covered stent alone insertion, as measured by survival.

  17. The impact of precise robotic lesion length measurement on stent length selection: ramifications for stent savings.

    Science.gov (United States)

    Campbell, Paul T; Kruse, Kevin R; Kroll, Christopher R; Patterson, Janet Y; Esposito, Michele J

    2015-09-01

    Coronary stent deployment outcomes can be negatively impacted by inaccurate lesion measurement and inappropriate stent length selection (SLS). We compared visual estimate of these parameters to those provided by the CorPath 200® Robotic PCI System. Sixty consecutive patients who underwent coronary stent placement utilizing the CorPath System were evaluated. The treating physician assessed orthogonal images and provided visual estimates of lesion length and SLS. The robotic system was then used for the same measures. SLS was considered to be accurate when visual estimate and robotic measures were in agreement. Visual estimate SLSs were considered to be "short" or "long" if they were below or above the robotic-selected stents, respectively. Only 35% (21/60) of visually estimated lesions resulted in accurate SLS, whereas 33% (20/60) and 32% (19/60) of the visually estimated SLSs were long and short, respectively. In 5 cases (8.3%), 1 less stent was placed based on the robotic lesion measurement being shorter than the visual estimate. Visual estimate assessment of lesion length and SLS is highly variable with 65% of the cases being inaccurately measured when compared to objective measures obtained from the robotic system. The 32% of the cases where lesions were visually estimated to be short represents cases that often require the use of extra stents after the full lesion is not covered by 1 stent [longitudinal geographic miss (LGM)]. Further, these data showed that the use of the robotic system prevented the use of extra stents in 8.3% of the cases. Measurement of lesions with robotic PCI may reduce measurement errors, need for extra stents, and LGM. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Initial experience with a new biodegradable airway stent in children: Is this the stent we were waiting for?

    Science.gov (United States)

    Antón-Pacheco, Juan L; Luna, Carmen; García, Enrique; López, María; Morante, Rocío; Tordable, Cristina; Palacios, Alba; de Miguel, Mónica; Benavent, Isabel; Gómez, Andrés

    2016-06-01

    To report our experience with a new type of biodegradable airway stent in the setting of severe tracheobronchial obstruction in children. We conducted a retrospective and prospective (since June 2014) study of pediatric patients with severe airway obstruction treated with biodegradable stents in our institution between 2012 and 2015. The following data were collected: demographics, indication for stenting, bronchoscopic findings, insertion technique complications, clinical outcome, stent related complications, re-stenting, and time of follow-up. Thirteen custom-made polydioxanone stents were placed in four infants (mean age, 4 months) with severe tracheobronchial obstruction: tracheomalacia (two patients), bronchomalacia (1), and diffuse tracheal stenosis (1). All the stents were bronchoscopically inserted uneventfully. Immediate and maintained clinical improvement was observed in every case. No major stent related complications have occurred and only mild or moderate granulation tissue was observed during surveillance bronchoscopy. Two patients required repeated stenting as expected. All the patients are alive and in a good respiratory condition with a follow-up ranging from 5 to 40 months. Biodegradable airway stents seem to be safe, effective, and cause fewer complications than other types of stents. They can be an alternative to the classic metallic or plastic stents for severe tracheal stenosis or malacia in small children. More experience is needed in order to establish the definite clinical criteria for their use in pediatric patients. Pediatr Pulmonol. 2016;51:607-612. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  19. Prospective Multicenter Study on the Challenges Inherent to Using Large Cell-Type Stents for Bilateral Stent-in-Stent Placement in Patients with Inoperable Malignant Hilar Biliary Obstruction.

    Science.gov (United States)

    Yang, Min Jae; Kim, Jin Hong; Hwang, Jae Chul; Yoo, Byung Moo; Lee, Sang Hyub; Ryu, Ji Kon; Kim, Yong-Tae; Woo, Sang Myung; Lee, Woo Jin; Jeong, Seok; Lee, Don Haeng

    2018-06-22

    Although endoscopic bilateral stent-in-stent placement is challenging, many recent studies have reported promising outcomes regarding technical success and endoscopic reintervention. This study aimed to evaluate the technical feasibility of stent-in-stent placement using large cell-type stents in patients with inoperable malignant hilar biliary obstruction. Forty-three patients with inoperable malignant hilar biliary obstruction from four academic centers were prospectively enrolled from March 2013 to June 2015. Bilateral stent-in-stent placement using two large cell-type stents was successfully performed in 88.4% of the patients (38/43). In four of the five cases with technical failure, the delivery sheath of the second stent became caught in the hook-cross-type vertex of the large cell of the first stent, and subsequent attempts to pass a guidewire and stent assembly through the mesh failed. Functional success was achieved in all cases with technical success. Stent occlusion occurred in 63.2% of patients (24/38), with a median patient survival of 300 days. The median stent patency was 198 days. The stent patency rate was 82.9%, 63.1%, and 32.1% at 3, 6, and 12 months, respectively. Endoscopic re-intervention was performed in 14 patients, whereas 10 underwent percutaneous drainage. Large cell-type stents for endoscopic bilateral stent-in-stent placement showed acceptable functional success and stent patency when technically successful. However, the technical difficulty associated with the entanglement of the second stent delivery sheath in the hook-cross-type vertex of the first stent may preclude large cell-type stents from being considered as a dedicated standard tool for stent-in-stent placement.

  20. Stent placement for tracheal stenosis in patients with esophageal cancer

    International Nuclear Information System (INIS)

    Takagi, Keigo; Hata, Yoshinobu; Sasamoto, Shuichi; Takahashi, Shoji; Sato, Fumitomo; Tamaki, Kazuyoshi; Goto, Hidenori; Yuasa, Rena

    2011-01-01

    Tracheal invasion including tracheal bifurcation due to esophageal cancer can sometimes cause serious complications of the airway, but such cases sometimes improve quickly following chemoradiation treatment. The absolute indications for stent replacement in the airway for this disorder and the optimal choice of stent are herein discussed. Between 1992 and 2010, 28 patients with airway stenosis, including 7 patients with esophago-tracheal fistula, were treated by placement of various stents; namely, 12 patients received Dumon stents, 3 patients had Dynamic stents, 10 patients were given Ultraflex stents, while 3 other patients were treated without the use of stents. Severe dyspnea in the supine position was observed, which mainly originated from invasion to the membranous portion of the trachea. Airway patency was maintained after stent replacement, although the median survival time of such cases was only 4 months. Three patients with severe dyspnea who could lie in a supine position recovered after undergoing chemoradiation treatment without stent replacement. No cases of stent removal were observed after chemoradiation treatment. Chemoradiation treatment for esophageal cancer was found to be effective for the management of airway disturbances, and thus the absolute indications for stent replacement are restricted to patients who cannot lie in a supine position due to severe impairment of ventilation during radiation therapy, as well as patients presenting with tracheobroncho-esophageal fistula. Concerning stent selection, a metal stent should be the first choice for tracheal stenosis due to its ease of insertion, because there is no substantial difference between silicone and metal stents regarding the treatment of tracheal stenosis. However, it is important to note that a silicone Y stent is useful for the treatment of tracheal bifurcation. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2002-04-01

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

  2. Temporary urethral covered stent - third year of experience

    International Nuclear Information System (INIS)

    Stojanovis, V.; Maksimovis, H.; Markovis, B.; Markovis, Z.

    2006-01-01

    Full text: In October 2003, a new generation of urethral stents ALLIUM, produced in Israel, were used at the Department of Interventional Radiology, CCS, in 18 patients with chronic stricture of bulbar urethra. The indications for insertion were determined according to well-known and recognized therapeutical protocols. The stent is made of nitinol wire with polyurethane cover. It is inserted under local anesthesia by a special self-expandable system that may be fixed or flexible. The stents we used were 3-6 cm long and 28 Fr wide. Radioscopic-assisted insertion was performed over formerly placed metal guide. Prior to insertion, balloon-catheter dilatation of stricture matching the stent width was carried out. Pre-insertion urethrotomy was performed in one case. The insertion technique is simple, presupposing the knowledge of older generations of techniques of urethral dilatation and insertion of self-expandable stents. The follow-up of results was done according to a priori established protocol including the following: UCG, uroflowmetry and interview with patients. Due to stent migration, the 'stent over stent' technique was applied in one case, while reposition by balloon-catheter outward traction was performed in two cases of caudal migration. No irritative discomforts were reported in the first 4 months after stent dwelling. Uroflowmetric controls verified at least four times better results than before the insertion. Given it is the question of covered stent, there is no possibility of proliferative secondary lumen obstruction. On account of soft structure and conic shape of posterior part of stent, no lesions of the external urethral sphincter were manifested. The stent is simply withdrawn after 6 months by outward traction using the forceps at the time when the stent construction turns into soft and straight wire. The first clinical experiences are very favorable and ALLIUM stent may be expected to be the stent of choice for chronic bulbar strictures

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

    International Nuclear Information System (INIS)

    Lee, Byung Hee; Kim, Kie Hwan; Chin, Soo Yil

    1998-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Byung Hee; Kim, Kie Hwan; Chin, Soo Yil [Korea Cancer Center Hospital, Seoul (Korea, Republic of)

    1998-09-01

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

  5. Effect of Covered Metallic Stents Compared With Plastic Stents on Benign Biliary Stricture Resolution

    Science.gov (United States)

    Coté, Gregory A.; Slivka, Adam; Tarnasky, Paul; Mullady, Daniel K.; Elmunzer, B. Joseph; Elta, Grace; Fogel, Evan; Lehman, Glen; McHenry, Lee; Romagnuolo, Joseph; Menon, Shyam; Siddiqui, Uzma D.; Watkins, James; Lynch, Sheryl; Denski, Cheryl; Xu, Huiping; Sherman, Stuart

    2017-01-01

    IMPORTANCE Endoscopic placement of multiple plastic stents in parallel is the first-line treatment for most benign biliary strictures; it is possible that fully covered, self-expandable metallic stents (cSEMS) may require fewer endoscopic retrograde cholangiopancreatography procedures (ERCPs) to achieve resolution. OBJECTIVE To assess whether use of cSEMS is noninferior to plastic stents with respect to stricture resolution. DESIGN, SETTING, AND PARTICIPANTS Multicenter (8 endoscopic referral centers), open-label, parallel, randomized clinical trial involving patients with treatment-naive, benign biliary strictures (N = 112) due to orthotopic liver transplant (n = 73), chronic pancreatitis (n = 35), or postoperative injury (n = 4), who were enrolled between April 2011 and September 2014 (with follow-up ending October 2015). Patients with a bile duct diameter less than 6 mm and those with an intact gallbladder in whom the cystic duct would be overlapped by a cSEMS were excluded. INTERVENTIONS Patients (N = 112) were randomized to receive multiple plastic stents or a single cSEMS, stratified by stricture etiology and with endoscopic reassessment for resolution every 3 months (plastic stents) or every 6 months (cSEMS). Patients were followed up for 12 months after stricture resolution to assess for recurrence. MAIN OUTCOMES AND MEASURES Primary outcome was stricture resolution after no more than 12 months of endoscopic therapy. The sample size was estimated based on the noninferiority of cSEMS to plastic stents, with a noninferiority margin of −15%. RESULTS There were 55 patients in the plastic stent group (mean [SD] age, 57 [11] years; 17 women [31%]) and 57 patients in the cSEMS group (mean [SD] age, 55 [10] years; 19 women [33%]). Compared with plastic stents (41/48, 85.4%), the cSEMS resolution rate was 50 of 54 patients (92.6%), with a rate difference of 7.2% (1-sided 95% CI, −3.0% to ∞; P stents was rejected. The mean number of ERCPs to achieve resolution

  6. Stenting of the SFA - indications, techniques,

    International Nuclear Information System (INIS)

    Rieger, J.; Treitl, M.; Reiser, M.; Ruppert, V.

    2006-01-01

    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.) [de

  7. Metallic stent and stereotactic conformal radiotherapy for hilar cholangiocarcinoma

    International Nuclear Information System (INIS)

    Li Yu; Wang Ning; Tian Qihe; Guo Zhanwen; Zhang Haibo; Song Liyan

    2005-01-01

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

  8. Scintigraphic examinations after stent implantation in central airways

    International Nuclear Information System (INIS)

    Richter, W.S.; Kettner, B.I.; Munz, D.L.

    1998-01-01

    Endotracheal and endobronchial stent implantation has been developed as an effective treatment of benign and malignant airway stenosis and of tracheo- or bronchoesophageal fistulas. The selection of the stent type depends on the kind and site of disease. Chest X-ray and bronchoscopy are the procedures of choice for monitoring of stent position, structure, and function. However, with scintigraphic methods the effects of stent implantation on pulmonary ventilation and perfusion can be assessed non-invasively. The validation of the effect of a stent implantation on mucociliary and tussive clearance remains to be elucidated. (orig.) [de

  9. Complications of esophageal stenting after radiotherapy and brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Yorozu, Atsunori; Dokiya, Takushi; Ogita, Mikio; Kutuki, Shoji; Oki, Yosuke [National Second Hospital of Tokyo (Japan)

    1997-11-01

    The purpose of our study was to evaluate safety and complications of stenting after radiotherapy and brachytherapy. Fifteen of 21 patients showed improvement of dysphagia by stenting. But 6 of 21 patients had perforation or massive bleeding relating to stents. The risk for perforation or hemorrhage appears to be even higher in patients who have previously undergone radical radiotherapy and brachytherapy within one month before stenting. Stenting at 6 months or more after radical radiotherapy seems to be an effective and safe method of long-lasting palliation for severe dysphagia with recurrent esophageal cancer. (author)

  10. 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

  11. In vitro stent lumen visualisation of various common and newly developed femoral artery stents using MR angiography at 1.5 and 3 tesla.

    Science.gov (United States)

    Syha, R; Ketelsen, D; Kaempf, M; Mangold, S; Sixt, S; Zeller, T; Springer, F; Schick, F; Claussen, C D; Brechtel, K

    2013-02-01

    To evaluate stent lumen assessment of various commonly used and newly developed stents for the superficial femoral artery (SFA) using MR angiography (MRA) at 1.5 and 3 T. Eleven nitinol stents and one cobalt-chromium stent were compared regarding stent lumen visualisation using a common three-dimensional MRA sequence. Maximum visible stent lumen width and contrast ratio were analysed in three representative slices for each stent type. A scoring system for lumen visualisation was applied. Nitinol stents showed significantly better performance than the cobalt chromium stent (P stent lumen ranged between 43.4 and 95.5 %, contrast ratio between 7.2 and 110.6 %. Regarding both field strengths, seven of the nitinol stents were classified as "suitable". Three nitinol stents were "limited", and one nitinol stent and the cobalt chromium stent were "not suitable". Intraluminal loss of signal and artefacts of most of the SFA stents do not markedly limit assessment of stent lumen by MRA at 1.5 and 3 T. MRA can thus be considered a valid technique for detection of relevant in-stent restenosis. Applied field strength does not strongly influence stent lumen assessment in general, but proper choice of field strength might be helpful.

  12. Prospective Evaluation of Two iStent® Trabecular Stents, One iStent Supra® Suprachoroidal Stent, and Postoperative Prostaglandin in Refractory Glaucoma: 4-year Outcomes.

    Science.gov (United States)

    Myers, Jonathan S; Masood, Imran; Hornbeak, Dana M; Belda, Jose I; Auffarth, Gerd; Jünemann, Anselm; Giamporcaro, Jane Ellen; Martinez-de-la-Casa, Jose M; Ahmed, Iqbal Ike K; Voskanyan, Lilit; Katz, L Jay

    2018-03-01

    This study evaluates long-term outcomes of two trabecular micro-bypass stents, one suprachoroidal stent, and postoperative prostaglandin in eyes with refractory open angle glaucoma (OAG). Prospective ongoing 5-year study of 80 eligible subjects (70 with 4-year follow-up) with OAG and IOP ≥ 18 mmHg after prior trabeculectomy and while taking 1-3 glaucoma medications. Subjects received two iStent ® trabecular micro-bypass stents, one iStent Supra ® suprachoroidal stent, and postoperative travoprost. Postoperative IOP was measured with medication and annually following medication washouts. Performance was measured by the proportion of eyes with ≥ 20% IOP reduction on one medication (the protocol-specified prostaglandin) versus preoperative medicated IOP (primary outcome); and the proportion of eyes with postoperative IOP ≤ 15 and ≤ 18 mmHg on one medication (secondary outcome). Additional clinical and safety data included medications, visual field, pachymetry, gonioscopy, adverse events, visual acuity, and slit-lamp and fundus examinations. Preoperatively, mean medicated IOP was 22.0 ± 3.1 mmHg on 1.2 ± 0.4 medications, and mean unmedicated IOP was 26.4 ± 2.4 mmHg. Postoperatively, among eyes without later cataract surgery, mean medicated IOP at all visits through 48 months was ≤ 13.7 mmHg (≥ 37% reduction), and annual unmedicated IOP was ≤ 18.4 mmHg (reductions of ≥ 30% vs. preoperative unmedicated IOP and ≥ 16% vs. preoperative medicated IOP). At all postoperative visits among eyes without additional surgery or medication, ≥ 91% of eyes had ≥ 20% IOP reduction on one medication versus preoperative medicated IOP. At month 48, 97 and 98% of eyes achieved IOP ≤ 15 and ≤ 18 mmHg, respectively, on one medication. Six eyes required additional medication, no eyes required additional glaucoma surgery, and safety measurements were favorable throughout follow-up. IOP control was achieved safely with two

  13. 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.

  14. [Treatment of tracheobronchomalacia with expandable metallic stents].

    Science.gov (United States)

    Antón-Pacheco Sánchez, J; García Vázquez, A; Cuadros García, J; Cano Novillo, I; Villafruela Sanz, M; Berchi García, F J

    2002-10-01

    Tracheomalacia is an unfrequent disease that causes tracheal collapse during breathing. It is generally associated to esophageal atresia, but cases of primary tracheomalacia and others secondary to extrinsic compression, have also been described. Spontaneous resolution is generally the rule and only a few cases need surgical treatment. When this therapy fails or is not indicated for any reason, endoluminal tracheobronchial stents may be used. We have treated two patients with four expandable metallic stents: one had severe tracheomalacia associated to esophageal atresia and the other tracheobronchomalacia secondary to cardiomegaly. Results have been good in both cases.

  15. The interventional treatment with two stents in malignant hilar obstruction

    International Nuclear Information System (INIS)

    Gao Kun; Dai Dingke; Zhao Renyou; Qian Xiaojun

    2006-01-01

    Objective: To evaluate the methodology of interventional treatment with two stents in malignant hilar obstructions. Methods: Retrospectively analyzing the two stents, interventional management of unresectable malignant hilar obstruction in 22 patients included unilateral and bilateral puncture routes for placing 'T' shape stent set and 'Y' shape stent set, respectively; together with recording the related complications. Results: The overall technical success rate was 100%, without severe complication. The total serum bilirubin reduced from (337.9 + 81.7) μmol/L before procedure to (129.1 + 51.1) μmol/L after the stent placement. Stent obstruction was found in 8 cases at 6 months; 5 cases by the time of 6-12 months and only 2 cases after 1 year. Conclusion: The method of two stents interventional treatment is a safe and useful management for malignant hilar obstructions. (authors)

  16. A Case of Late Femoral Pseudoaneurysm Caused by Stent Disconnection

    International Nuclear Information System (INIS)

    Rivolta, Nicola; Fontana, Federico; Piffaretti, Gabriele; Tozzi, Matteo; Carrafiello, Gianpaolo

    2010-01-01

    We present the case of a late superficial femoral artery stent disconnection causing an asymptomatic pseudoaneurysm successfully treated with a stent-graft. A 67-year-old female was referred to our department for evaluation of claudication of the left lower limb and was diagnosed to have a total occlusion of the superficial femoral artery. Three nitinol stents were used to revascularize this artery. At 48 months, duplex-ultrasonography control revealed the presence of a 45-mm saccular femoral dilatation; X-rays and CT angiography showed fractures of the proximal stents and the presence of a pseudoaneurysm at the site of the distal stents disconnection. The pseudoaneurysm was excluded using two stent-grafts. We conclude that patients and surgeons should be aware of structural complications with all stents. Rigorous follow-up controls should be mandatory. Endovascular repair proved to be feasible and durable to manage a previous endovascular procedure.

  17. 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...

  18. Role of stents and laser therapy in biliary strictures

    Science.gov (United States)

    Chennupati, Raja S.; Trowers, Eugene A.

    2001-05-01

    The most frequent primary cancers causing malignant obstructive jaundice were pancreatic cancer (57%), hilar biliary cancer (19% including metastatic disease), nonhilar biliary cancer (14%) and papillary cancer (10%). Endoscopic stenting has widely replaced palliative surgery for malignant biliary obstruction because of its lower risk and cost. Self-expandable metal stents are the preferred mode of palliation for hilar malignancies. Plastic stents have a major role in benign biliary strictures. Major complications and disadvantages associated with metallic stents include high cost, cholangitis. malposition, migration, unextractability, and breakage of the stents, pancreatitis and stent dysfunction. Dysfunction due to tumor ingrowth can be relieved by thermal methods (argon plasma coagulator therapy). We present a concise review of the efficacy of metallic stents for palliation of malignant strictures.

  19. Colorectal Stenting in Malignant Large Bowel Obstruction: The Learning Curve

    Directory of Open Access Journals (Sweden)

    D. Williams

    2011-01-01

    Full Text Available Aim. Self-expanding metal stents (SEMSs are increasingly used for the palliation of metastatic colorectal cancer and as a bridge to surgery for obstructing tumours. This case series analyses the learning curve and changes in practice of colorectal stenting over a three year period. Methods. A study of 40 patients who underwent placement of SEMS for the management of colorectal cancer. Patients spanned the learning curve of a single surgeon endoscopist. Results. Technical success rates increased from 82% initially, using an average of 1.7 stents per procedure, to a 94% success rate where all patients were stented using a single stent. There has been a change in practice from elective palliative stenting toward emergency preoperative stenting. Conclusion. There is a steep learning curve for the use of SEMS in the management of malignant colorectal bowel obstruction. We suggest that at least 20 cases are required for an operator to be considered experienced.

  20. Results of the new nitinol self-expandable stents for distal biliary structures

    NARCIS (Netherlands)

    Smits, M.; Huibregtse, K.; Tytgat, G.

    1995-01-01

    The nitinol stent is a self-expandable spiral stent made of nickel-titanium alloy. We performed a pilot study to evaluate the method of stent insertion and stent efficacy. Twenty-eight patients with irresectable malignancy had nitinol stents inserted for obstructive jaundice due to distal biliary

  1. Endoscopic stenting in bile duct cancer increases liver volume.

    Science.gov (United States)

    Lee, Chang Hun; Kim, Seong Hun; Kim, In Hee; Kim, Sang Wook; Lee, Soo Teik; Kim, Dae Ghon; Yang, Jae Do; Yu, Hee Chul; Cho, Baik Hwan; Lee, Seung Ok

    2014-09-01

    Objective evaluation tools for assessing the effectiveness of stenting in palliative treatment of malignant biliary obstruction are not satisfactory. Effects of biliary stenting on liver volume change have never been studied. We aimed to use volumetry to analyze liver volume changes after endoscopic stenting in bile duct cancer according to the location and number of stents. Retrospective review. University hospital. Patients with a diagnosis of hilar or distal bile duct cancer and who underwent biliary metal stenting. ERCP with self-expandable metal stent placement. Liver volume change after biliary stenting and its comparison according to the location (hilar vs distal common bile duct) and number (hilar bilateral vs hilar unilateral). There were 60 patients; 31 were treated for hilar bile duct cancer (13 for bilateral stent and 18 for unilateral stent) and 29 for distal bile duct cancer. Overall mean follow-up duration was 11.7 ± 4.9 weeks. Liver volume increased 17.4 ± 24.1%. The rate of liver growth was rapid during the early period from 4 to 8 weeks. Stenting in hilar bile duct cancer tended to increase liver volume more than distal biliary stents (22.5% vs 11.9%, P = .091). In hilar bile duct cancer, unilateral and bilateral stents showed similar liver volume increases (20.1% and 25.8%, respectively; P = .512). Single center, retrospective. Biliary stenting markedly increased liver volume in both hilar and distal bile duct cancer. Our data suggest that liver volume assessment could be a useful tool for evaluating stent efficacy. Copyright © 2014 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

  2. Multidisciplinary approach to carotid stenting.

    Science.gov (United States)

    Mak, C S; Chambers, B R; Clark, D J; Molan, M; Brooks, M; Roberts, N; Fell, G; Roberts, A K; New, G; Donnan, G A

    2011-11-01

    Stroke neurologists, vascular surgeons, interventional neuroradiologists and interventional cardiologists have embraced carotid angioplasty and stenting (CAS) because of potential advantages over carotid endarterectomy (CEA). At Austin Health, a multidisciplinary neuro-interventional group was formed to standardise indications and facilitate training. The aims of this study were to describe our organisational model and to determine whether 30-day complications and early outcomes were similar to those of major trials. A clinical protocol was developed to ensure optimal management. CAS was performed on patients with high medical risk for CEA, with technically difficult anatomy for CEA, or who were randomised to CAS in a trial. From October 2003 to May 2008, 47 patients (34 male, mean age 71.5) underwent CAS of 50 carotid arteries. Forty-three cases had ipsilateral carotid territory symptoms within the previous 12 months. The main indications for CAS were high risk for CEA (n= 17) and randomised to CAS (n= 21). Interventionists were proctored in 27 cases. The procedural success rate was 94% with two cases abandoned because of anatomical problems and one because of on-table angina. Hypotension requiring vasopressor therapy occurred in 12 cases (24%). The duration of follow up was one to 44 months (mean 6.8 months). The 30-day rate of peri-procedural stroke or death was 6% and the one-year rate of peri-procedural stroke or death or subsequent ipsilateral stroke was 10.6%. Restenosis occurred in 13% (all asymptomatic). A multidisciplinary approach is a useful strategy for initiating and sustaining a CAS programme. © 2011 The Authors. Internal Medicine Journal © 2011 Royal Australasian College of Physicians.

  3. The Role Of Inflammation In Stent Restenosis More Than 1 Year Afetr Drug Eluting Stent Implantation

    Directory of Open Access Journals (Sweden)

    Hasan Shemirani

    2011-09-01

    Full Text Available Background: In stent restenosis (ISR following endovascular interventions is the main limitation of their long-term success. Despite advances have been made during recent years to decrease restenosis, it remains a challenging clinical problem.The aim of this study was to evaluate the relationship between angiographic coronary in stent restenosis, inflammation after successful stent implantation. Methods: This study included 78 patients, 35year old and higher who underwent coronary angiography more than 1 year after drug-eluting stent (DES implantation because of symptoms suggestive ischemia. Patients were divided into ISR group (case and patent stent group (control according to angiography results. For all patients blood lipids and high sensitivity C-Reactive Protein (hsCRP were measured simultaneously. Results: Age, sex, hypertension, current smoking, and lipid profile other than High Density Lipoprotein (HDL-C of patients in the case and control groups were similar .However, HDL-C < 40mg/L was more prevalent with ISR (66.7% vs. 30.8%, p=0.002. The hsCRP level was 2.98±2.06 mg/L in the case group and 2.50±1.80 mg/L in the control group. There were no significant differences in mean hsCRP concentration between the two groups (p=0.14, however mean hsCRP level was significantly higher in men of case group than control group (3.35mg/L vs. 2.21mg/L, p<0.05. Conclusion: This study demonstrates that in men but not in women inflammation may be a predictor of in stent restenosis more than 1 year after drug eluting stent implantation. Also, high-density lipoprotein (HDL probably has protective effect against stent restenosis.

  4. Overtime evaluation of the vascular HEALing process after everolimus-eluting stent implantation by optical coherence tomography. The HEAL-EES study

    Energy Technology Data Exchange (ETDEWEB)

    Otsuki, Shuji; Brugaletta, Salvatore, E-mail: sabrugal@clinic.ub.es; Sabaté, Manel; Shiratori, Yoshitaka; Gomez-Monterrosas, Omar; Scalone, Giancarla; Romero-Villafañe, Sebastian; Hernández-Enríquez, Marco; Freixa, Xavier; Martín-Yuste, Victoria; Masotti, Mónica

    2016-06-15

    Purpose: Second-generation drug-eluting stent (DES) have shown a better safety and efficacy as compared to first generation DES due to an improved vascular healing process. This process has not been so far evaluated in vivo in an overtime fashion by optical coherent tomography (OCT). We sought to evaluate the vascular healing process after everolimus-eluting stent (EES) implantation at 6, 9 and 12 months, by OCT. Methods: Consecutive 36 patients undergoing percutaneous coronary intervention with EES were randomized 1:1:1 to receive OCT imaging at 6 (group A), 9 (group B) or 12-month follow-up (group C). One patient from group C was excluded because of target lesion revascularization at 1-month, whereas 5 patients withdraw the informed consent. Finally, 30 patients were analyzed. Results: Neointimal thickness was not different between 3 groups (group A: 99.50 [94.06–127.79] μm, group B: 107.26 [83.48–133.59] μm, group C: 127.67 [102.51–138.49] μm; p = 0.736). Although the percentage of “uncovered struts” was significantly higher in group A as compared to the other groups (8.0% vs. 4.4% vs. 2.9%, respectively; p = 0.180), the ratio of uncovered to total struts per section < 30% was similar between 3 groups (0.3% vs. 0.3% vs. 0%, respectively; p = 1.000). Conclusion: Healing process following EES implantation seems almost completed at 6-month follow-up. These data, which need to be confirmed in a larger study, may support the decision to shorten dual antiplatelet therapy. - Highlights: • Healing process following everolimus-eluting stent implantation is complete at 6-month • There are no difference in RUTTS > 30% between 6, 9 and 12 months analyses. • This finding may support to shorten dual antiplatelet therapy in this context.

  5. Mechanical Properties of Metallic Stents: How Do These Properties Influence the Choice of Stent for Specific Lesions?

    International Nuclear Information System (INIS)

    Dyet, John F.; Watts, William G.; Ettles, Duncan F.; Nicholson, Anthony A.

    2000-01-01

    Purpose: To assess selected balloon-expandable and self-expanding stents for radial force, flexibility, radio-opacity, and trackability, and to relate these physical characteristics to potential indications for placement.Methods: Force-strain curves were plotted for each stent and the force required to produce 50% luminal narrowing was recorded. The ability of the stent to show elastic recoil following deformation was also noted. Flexibility was measured by bending the stents against a force transducer and recording the force required per degree of flexion. Radio-opacity was measured by comparing each stent against a standard aluminum step wedge. Trackability was measured by testing the ability of the stent on its delivery system to track over angles of 90 deg. and 60 deg. Results: The balloon-expandable stents showed greater radial strength and radio-opacity but, apart from the AVE Iliac Bridge stent, showed poorer flexibility and trackability. The self-expanding stents showed less radial force but were able to re-expand following deformity. They were generally more flexible and had better trackability but lower radio-opacity.Conclusion: There is no stent which exhibits all the ideal properties required and therefore the interventionist will need to keep a range of stents available if all lesions are to be addressed

  6. Covered stent placement for the treatment of malignant superior vena cava syndrome: Is unilateral covered stenting and effective?

    International Nuclear Information System (INIS)

    Cho, Young Hoon; Gwon, Dong Il; Ko, Gi Young; Ko, Heung Kyu; Kim, Jin Hyoung; Shin, Ji Hoon; Yoon, Hyun Ki; Sung, Kyu Bo

    2014-01-01

    To evaluate the safety and efficacy of unilateral covered stent placement in patients with malignant superior vena cava (SVC) syndrome. Between October 2008 and November 2012, expanded polytetrafluoroethylene-covered stent placement for malignant SVC syndrome was performed in 40 consecutive patients (35 men and five women; mean age, 61.4 years; range, 35-81 years). All covered stents were unilaterally placed within the SVC or across the venous confluence when needed to relieve venous obstruction and prevent tumor overgrowth, regardless of patency of contralateral brachiocephalic veins. Stent placement was technically successful in all patients. There were no major complications. Of the 37 patients symptomatic prior to stent placement, 34 (92%) experienced complete symptomatic relief 1-8 days after stent placement. Of the 29 patients who underwent covered stent placement across the venous confluence, nine patients had patent contralateral brachiocephalic veins prior to stent placement. However, no sign of SVC obstruction or contralateral upper extremity venous thrombosis was observed during the follow-up period. Kaplan-Meier analysis revealed median patient survival of 163 days. Stent occlusion occurred in four (10%) of 40 patents. Cumulative stent patency rates at 1, 3, 6, and 12 months were 95%, 92%, 86%, and 86%, respectively. Unilateral covered stent placement appears to be a safe and effective method for treating malignant SVC syndrome, despite the location of SVC occlusion.

  7. Covered stent placement for the treatment of malignant superior vena cava syndrome: Is unilateral covered stenting and effective?

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Young Hoon; Gwon, Dong Il; Ko, Gi Young; Ko, Heung Kyu; Kim, Jin Hyoung; Shin, Ji Hoon; Yoon, Hyun Ki; Sung, Kyu Bo [Dept. of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of)

    2014-02-15

    To evaluate the safety and efficacy of unilateral covered stent placement in patients with malignant superior vena cava (SVC) syndrome. Between October 2008 and November 2012, expanded polytetrafluoroethylene-covered stent placement for malignant SVC syndrome was performed in 40 consecutive patients (35 men and five women; mean age, 61.4 years; range, 35-81 years). All covered stents were unilaterally placed within the SVC or across the venous confluence when needed to relieve venous obstruction and prevent tumor overgrowth, regardless of patency of contralateral brachiocephalic veins. Stent placement was technically successful in all patients. There were no major complications. Of the 37 patients symptomatic prior to stent placement, 34 (92%) experienced complete symptomatic relief 1-8 days after stent placement. Of the 29 patients who underwent covered stent placement across the venous confluence, nine patients had patent contralateral brachiocephalic veins prior to stent placement. However, no sign of SVC obstruction or contralateral upper extremity venous thrombosis was observed during the follow-up period. Kaplan-Meier analysis revealed median patient survival of 163 days. Stent occlusion occurred in four (10%) of 40 patents. Cumulative stent patency rates at 1, 3, 6, and 12 months were 95%, 92%, 86%, and 86%, respectively. Unilateral covered stent placement appears to be a safe and effective method for treating malignant SVC syndrome, despite the location of SVC occlusion.

  8. Metallic stents provide better QOL than plastic stents in patients with stricture of unresectable advanced esophageal cancer

    International Nuclear Information System (INIS)

    Ohta, Kazuki; Nagahara, Akihito; Iijima, Katsuyori

    2006-01-01

    The aim of this study was to elucidate the utility and safety of treatment with esophageal stents (plastic and metallic stents) for unresectable advanced esophageal cancer. Between 1992 and 2002, 14 cases of unresectable advanced esophageal cancer were treated with esophageal stents (the plastic stent group, 7 cases; and the metallic stent group, 7 cases). Of these, 10 cases had a history of chemotherapy and or radiotherapy. An improvement in oral intake and performance status (PS), survival time, periods at home, and adverse events were compared between the two groups. After stenting, oral intake and PS were significantly improved in the metallic stent group. Follow-up at home was possible in 71.4%. There was no significant difference in survival or duration of time at home between the two groups. All adverse events were controllable and there was no difference between the two groups. Stenting not only improved oral intake and PS but also allowed a stay at home, resulting in a marked improvement in patients' quality of life (QOL). Stenting was performed safely even in cases with a history of radiotherapy. There was no difference in survival, ratios of staying at home, and safety between the two groups, but QOL was significantly improved in the metallic stent group. These outcomes indicate that placement of metallic stents should be actively considered to treat stricture due to advanced esophageal cancer. (author)

  9. 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. © 2014 Wiley Periodicals, Inc.

  10. Stent Thrombosis is the Primary Cause of ST-Segment Elevation Myocardial Infarction following Coronary Stent Implantation

    DEFF Research Database (Denmark)

    Kristensen, Søren Lund; Galløe, Anders M; Thuesen, Leif

    2014-01-01

    Background: The widespread use of coronary stents has exposed a growing population to the risk of stent thrombosis, but the importance in terms of risk of ST-segment elevation myocardial infarctions (STEMIs) remains unclear. Methods: We studied five years follow-up data for 2,098 all-comer patients...... treated with coronary stents in the randomized SORT OUT II trial (mean age 63.6 yrs. 74.8% men). Patients who following stent implantation were readmitted with STEMI were included and each patient was categorized ranging from definite-to ruled-out stent thrombosis according to the Academic Research...... Consortium definitions. Multivariate logistic regression was performed on selected covariates to assess odds ratios (ORs) for definite stent thrombosis. Results: 85 patients (4.1%), mean age 62.7 years, 77.1% men, were admitted with a total of 96 STEMIs, of whom 60 (62.5%) had definite stent thrombosis...

  11. Predictive factors for the failure of endoscopic stent-in-stent self-expandable metallic stent placement to treat malignant hilar biliary obstruction.

    Science.gov (United States)

    Sugimoto, Mitsuru; Takagi, Tadayuki; Suzuki, Rei; Konno, Naoki; Asama, Hiroyuki; Watanabe, Ko; Nakamura, Jun; Kikuchi, Hitomi; Waragai, Yuichi; Takasumi, Mika; Sato, Yuki; Hikichi, Takuto; Ohira, Hiromasa

    2017-09-14

    To investigate the factors predictive of failure when placing a second biliary self-expandable metallic stents (SEMSs). This study evaluated 65 patients with an unresectable malignant hilar biliary obstruction who were examined in our hospital. Sixty-two of these patients were recruited to the study and divided into two groups: the success group, which consisted of patients in whom a stent-in-stent SEMS had been placed successfully, and the failure group, which consisted of patients in whom the stent-in-stent SEMS had not been placed successfully. We compared the characteristics of the patients, the stricture state of their biliary ducts, and the implemented endoscopic retrograde cholangiopancreatography (ERCP) procedures between the two groups. The angle between the target biliary duct stricture and the first implanted SEMS was significantly larger in the failure group than in the success group. There were significantly fewer wire or dilation devices (ERCP catheter, dilator, or balloon catheter) passing the first SEMS cell in the failure group than in the success group. The cut-off value of the angle predicting stent-in-stent SEMS placement failure was 49.7 degrees according to the ROC curve (sensitivity 91.7%, specificity 61.2%). Furthermore, the angle was significantly smaller in patients with wire or dilation devices passing the first SEMS cell than in patients without wire or dilation devices passing the first SEMS cell. A large angle was identified as a predictive factor for failure of stent-in-stent SEMS placement.

  12. Scintigraphic examinations after stent implantation in central airways; Szintigraphische Untersuchungen bei Stents in den zentralen Atemwegen

    Energy Technology Data Exchange (ETDEWEB)

    Richter, W.S.; Kettner, B.I.; Munz, D.L. [Klinik und Poliklinik fuer Nuklearmedizin, Universitaetsklinikum Charite, Medizinische Fakulteat der Humboldt-Univ. zu Berlin (Germany)

    1998-03-01

    Endotracheal and endobronchial stent implantation has been developed as an effective treatment of benign and malignant airway stenosis and of tracheo- or bronchoesophageal fistulas. The selection of the stent type depends on the kind and site of disease. Chest X-ray and bronchoscopy are the procedures of choice for monitoring of stent position, structure, and function. However, with scintigraphic methods the effects of stent implantation on pulmonary ventilation and perfusion can be assessed non-invasively. The validation of the effect of a stent implantation on mucociliary and tussive clearance remains to be elucidated. (orig.) [Deutsch] Die endotracheale und -bronchiale Stentimplantation wurde in den letzten Jahren als effektive Massnahme bei benignen und malignen Stenosen der Atemwege, drohendem Atemwegsverschluss und bei tracheo- bzw. bronchooesophagealen Fisteln eingefuehrt. Der gewaehlte Stenttyp richtet sich nach dem Implantationsort und den krankheitsbedingten Veraenderungen. Zum Monitoring von Lage, Struktur und Funktion eines Stents dienen Thoraxroentgenaufnahmen und die Bronchoskopie. Nuklearmedizinische Verfahren koennen nicht-invasiv den Effekt der Stenteinlage auf Lungenventilation und -perfusion belegen. Die Validierung des Effekts einer Stentimplantation auf die mukoziliaere und tussive Clearance steht noch aus. (orig.)

  13. Creation of individual ideally shaped stents using multi-slice CT: in vitro results from the semi-automatic virtual stent (SAVS) designer

    International Nuclear Information System (INIS)

    Hyodoh, Hideki; Katagiri, Yoshimi; Hyodoh, Kazusa; Akiba, Hidenari; Hareyama, Masato; Sakai, Toyohiko

    2005-01-01

    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. (orig.)

  14. Stent implantation into the tracheo-bronchial system in rabbits: histopathologic sequelae in bare metal vs. drug-eluting stents.

    Science.gov (United States)

    Sigler, Matthias; Klötzer, Julia; Quentin, Thomas; Paul, Thomas; Möller, Oliver

    2015-12-01

    Stent implantation into the tracheo-bronchial system may be life-saving in selected pediatric patients with otherwise intractable stenosis of the upper airways. Following implantation, significant tissue proliferation may occur, requiring re-interventions. We sought to evaluate the effect of immunosuppressive coating of the stents on the extent of tissue proliferation in an animal model. Bare metal and sirolimus-coated stents (Bx Sonic and Cypher Select, Johnson & Johnson, Cordis) were implanted into non-stenotic lower airways of New Zealand white rabbits (weight 3.1 to 4.8 kg). Three stents with sirolimus coating and six bare metal stents could be analyzed by means of histology and immunohistochemistry 12 months after implantation. On a macroscopic evaluation, all stents were partially covered with a considerable amount of whitish tissue. Histologically, these proliferations contained fiber-rich connective tissue and some fibromuscular cells without significant differences between both stent types. The superficial tissue layer was formed by typical respiratory epithelium and polygonal cells. Abundant lymphocyte infiltrations and moderate granulocyte infiltrations were found in both groups correspondingly, whereas foreign-body reaction was more pronounced around sirolimus-eluting stents. After stent implantation in the tracheo-bronchial system of rabbits, we found tissue reactions comparable to those seen after stent implantation into the vascular system. There was no difference between coated and uncoated stents with regard to quality and quantity of tissue proliferation. We found, however, a significantly different inflammatory reaction with a more pronounced foreign-body reaction in sirolimus-coated stents. In our small series, drug-eluting stents did not exhibit any benefit over bare metal stents in an experimental setting.

  15. 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.)

  16. Covered stent to exclude intravascular thrombus.

    Science.gov (United States)

    Liistro, Francesco; Stankovic, Goran; Di Mario, Carlo; Montorfano, Matteo; Briguori, Carlo; Colombo, Antonio

    2002-04-01

    To describe the utility of stent-graft implantation to avoid distal embolization from a large thrombus-containing lesion. A 67-year-old man was evaluated for recent onset of disabling left leg claudication. Angiography disclosed a mobile lobular mass occluding the left common iliac artery; irregular staining suggested an atherothrombotic lesion. Through a percutaneous ipsilateral access and an 8-F sheath, a balloon-expandable Jostent peripheral stent-graft was positioned with the distal edge immediately proximal to the internal iliac artery ostium. A prominent "waist" at the center of the balloon confirmed entrapment of the thrombotic mass. Completion angiography showed an optimal result with no residual stenosis or evidence of distal embolization. At 6-month follow-up, the patient was asymptomatic with angiographically documented luminal patency and no evidence of in-stent stenosis. Stent-graft implantation appears a viable treatment alternative for thrombus-containing lesions, particularly when the thrombotic material is localized or is in a large vessel.

  17. Hemi-Intravascular Stenting for Supermicrosurgical Anastomosis

    Directory of Open Access Journals (Sweden)

    Kensuke Tashiro, MD

    2017-11-01

    Conclusions:. Hemi-IVaS could be a useful alternative to conventional intravascular stenting techniques and is also effective for supermicrosurgical perforator-to-perforator anastomosis. Further studies are needed to improve the success rate and to explore its other possible utilizations in supermicrosurgery.

  18. 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.

  19. Oesphageal Stenting for palliation of malignant mesothelioma

    Directory of Open Access Journals (Sweden)

    Rahamim Joseph

    2008-01-01

    Full Text Available Abstract Dyspahgia in patients with malignant mesothelioma is usually due to direct infiltration of the eosophagus by the tumour. It can be distressing for the patient and challenging for the physician to treat. We describe three cases in which this condition has been successfully palliated with self expanding esophageal stents.

  20. Comparison of Tongue-in-Groove and Columellar Strut on Rotation and Projection in Droopy Nasal Tip: Contribution of a Cap Graft.

    Science.gov (United States)

    Demir, Uygar Levent

    2018-05-01

    Underrotation of the nasal tip with narrow nasolabial angle is a common nasal deformity that leads to a long nose appearance, named drooping nose. In these patients, there are various techniques described to correct droopy tip and to achieve a desirable nasal tip rotation such as lateral crural steal, lateral crural overlay, tongue-ingroove, columellar strut graft, tip rotation sutures, cephalic trimming, and others. In this study, the effects of tongue-in-groove (TIG) and columellar strut graft (CS) and the contribution of cap graft on nasal tip rotation and projection were evaluated. Twenty-eight consecutive patients who underwent open approach rhinoplasty by the same senior author (ULD) between January 2015 and December 2016 with the diagnosis of septonasal deformity and droopy nasal tip were included. In 9 of these patients nasal tip was constructed with strut graft, in 6 patients with both strut and cap grafts, in 6 patients with TIG technique and in 7 patients with both TIG and cap graft. Standardized right lateral images were taken preoperatively and 6 months postoperatively to use for further assessments. The nasal tip rotation was evaluated by measuring nasolabial angle (NLA) and the nasal projection (NP) was evaluated by using the Goode method. Finally, the postoperative values of NLA and NP at the 6th month were compared with preoperative recorded values in between groups. Each group showed increase at nasal projection; however, significance was present only in CS graft and TIG groups (P=0.011 and P=0.027 relatively). Each 4 groups showed significant increase in nasal tip rotation. In addition, the comparison of percent changes between preoperative and postoperative NP and NLA revealed no difference (P=0.56 and P=0.431 relatively). In conclusion, the authors argued that TIG and CS graft techniques are both reliable methods to correct droopy nasal tip and using additional cap graft over dome area when required is safe and useful.

  1. Funzionalizzazione della mandibola dopo ricostruzione con lembo libero rivascolarizzato di fibula "single strut". Al di là del deficit di verticalità.

    OpenAIRE

    Gessaroli, Manlio

    2009-01-01

    Obiettivi: Valutare la modalità  più efficace per la riabilitazione funzionale del limbo libero di fibula "single strut", dopo ampie resezioni per patologia neoplastica maligna del cavo orale. Metodi: Da una casistica di 62 ricostruzioni microvascolari con limbo libero di fibula, 11 casi sono stati selezionati per essere riabilitati mediante protesi dentale a supporto implantare. 6 casi sono stati trattati senza ulteriori procedure chirurgiche ad eccezione dell'implantologia (gruppo 1), a...

  2. Risk factors for proximal migration of biliary tube stents.

    Science.gov (United States)

    Kawaguchi, Yoshiaki; Ogawa, Masami; Kawashima, Yohei; Mizukami, Hajime; Maruno, Atsuko; Ito, Hiroyuki; Mine, Tetsuya

    2014-02-07

    To analyze the risk factors for biliary stent migration in patients with benign and malignant strictures. Endoscopic stent placement was performed in 396 patients with bile duct stenosis, at our institution, between June 2003 and March 2009. The indications for bile duct stent implantation included common bile duct stone in 190 patients, malignant lesions in 112, chronic pancreatitis in 62, autoimmune pancreatitis in 14, trauma in eight, surgical complications in six, and primary sclerosing cholangitis (PSC) in four. We retrospectively examined the frequency of stent migration, and analyzed the patient factors (disease, whether endoscopic sphincterotomy was performed, location of bile duct stenosis and diameter of the bile duct) and stent characteristics (duration of stent placement, stent type, diameter and length). Moreover, we investigated retrieval methods for migrated stents and their associated success rates. The frequency of tube stent migration in the total patient population was 3.5%. The cases in which tube stent migration occurred included those with common bile duct stones (3/190; 1.6%), malignant lesions (2/112; 1.8%), chronic pancreatitis (4/62; 6.5%), autoimmune pancreatitis (2/14; 14.3%), trauma (1/8; 12.5%), surgical complications (2/6; 33.3%), and PSC (0/4; 0%). The potential risk factors for migration included bile duct stenosis secondary to benign disease such as chronic pancreatitis and autoimmune pancreatitis (P = 0.030); stenosis of the lower bile duct (P = 0.031); bile duct diameter > 10 mm (P = 0.023); duration of stent placement > 1 mo (P = 0.007); use of straight-type stents (P stents (P stents was successful in all cases. The grasping technique, using a basket or snare, was effective for pig-tailed or thin and straight stents, whereas the guidewire cannulation technique was effective for thick and straight stents. Migration of tube stents within the bile duct is rare but possible, and it is important to determine the risk factors

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

    International Nuclear Information System (INIS)

    Maintz, D.; Fallenberg, E. M.; Heindel, W.; Fischbach, R.; Grude, M.

    2003-01-01

    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

  4. Comparison of Self-Expanding Polyethylene Terephthalate and Metallic Stents Implanted in Porcine Iliac Arteries

    International Nuclear Information System (INIS)

    Wilczek, Krzysztof; Scheerder, Ivan de; Wang Kai; Verbeken, Eric; Piessens, Jan

    1996-01-01

    Purpose: Comparison of the biocompatibility of self-expanding polyethylene terephthalate (PET) stents with self-expanding metallic stents (Wallstents). Methods: Diameter- and length-matched PET stents and Wallstents were symmetrically implanted in the paired iliac arteries of 13 crossbred domestic swine. Stent deployment was studied angiographically and with intravascular ultrasound immediately after stent implantation. The angiographic stented lumen diameter was measured using quantitative vessel analysis before, immediately after stenting, and at 6-week follow-up. Cross-section histopathology and area morphometry were performed. Results: Immediately poststenting, intravascular ultrasound revealed proximal dislocation of 5 of the 13 PET stents, whereas all metal stents were firmly embedded at the implantation site. At 6-week follow-up, three of the remaining PET stents were totally or subtotally occluded by organized thrombus, whereas all metal stents were patent. Compared with immediately poststenting, the angiographic lumen diameter within the five remaining PET stents was reduced by 30%, and that of the metallic stents was virtually unaltered (p < 0.02). This observation was confirmed by postmortem morphometry, wherein the PET-stented vessel segments a diameter stenosis of 40% was measured vs only 9% in the metallic stents (p < 0.0001). Conclusion: PET-stent deployment is difficult to control due to the lack of radiopacity of this stent. PET stents seem to be more thrombogenic and lead to significantly more neointimal proliferation than metallic stents

  5. 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.

  6. Self-made Palmaz stent: an experimental swine model study

    International Nuclear Information System (INIS)

    He Shicheng; Teng Gaojun; Guo Jinhe; Fang Wen

    2000-01-01

    Objective: To investigate the histologic changes and physicochemical stability of self-made Palmaz stent placed in swine arteries. Methods: The self-made Palmaz stent was made of 316L stainless steel wire. Nine stents were respectively placed within internal carotid, renal and iliac arteries of six pigs. Pigs were euthanized at intervals of 0.5, 1 and 3 months respectively and angiography were performed. Immediately followed by light and electro scanning microscopy for the stent zones. Results: All stents were successfully implanted in the target arteries and were patent shown in the angiographic examination immediately after the stent placement. Eight stents (8/9) remained patent at the time before euthanasia. No migration of stent were shown in the follow-up angiography. Light and electron scanning microscopy showed that the surface of the stents was covered by a thin layer of endothelial cells 2 weeks after the procedure and completely covered after 4 weeks. No inflammation occurred. Conclusions: The self-made Palmaz stent has good physicochemical stability and histocompatibility with easy placement, rather long term patency, histopathologic stability and thus the promising for clinical application

  7. Factors leading to tracheobronchial self-expandable metallic stent fracture.

    Science.gov (United States)

    Chung, Fu-Tsai; Lin, Shu-Min; Chen, Hao-Cheng; Chou, Chun-Liang; Yu, Chih-Teng; Liu, Chien-Ying; Wang, Chun-Hua; Lin, Horng-Chyuan; Huang, Chien-Da; Kuo, Han-Pin

    2008-11-01

    This retrospective study was to determine factors that contribute to self-expandable metallic stent fracture in patients with tracheobronchial disease. From 2001 to 2006, 139 patients (age, 62.1 +/- 15.4 years; range, 23-87 years) with benign (n = 62) and malignant (n = 77) tracheobronchial disease received 192 Ultraflex (Boston Scientific, Natick, Mass) self-expandable metallic stents (98 in patients with benign disease and 94 in patients with malignant disease). Seventeen fractured self-expandable metallic stents were found; the incidence was 12.2% (17/139 patients) among patients with tracheobronchial disease. Tortuous airway (odds ratio, 4.06; 95% confidence interval, 1.04-18.34; P = .04) independently predicted self-expandable metallic stent fracture. Most self-expandable metallic stent fractures (64.7%, 11/17) were detected 500 to 1000 days after self-expandable metallic stent implantation. Clinical presentations for patients with fractured self-expandable metallic stents included dyspnea exacerbation (70.6%, 12/17) and cough (23.5%, 4/17). Self-expandable metallic stent fracture is not uncommon in patients with tracheobronchial disease. Tortuous airway is an independent predictor for it. Although management of the fractured self-expandable metallic stent in our study was feasible and safe, self-expandable metallic stents should be restricted to a more select population.

  8. Surgical stent for dental implant using cone beam CT images

    International Nuclear Information System (INIS)

    Choi, Hyung Soo; Kim, Gyu Tae; Choi, Yong Suk; Hwang, Eui Hwan

    2010-01-01

    The purpose of this study is to develop a surgical stent for dental implant procedure that can be easily applied and affordable by using cone beam computerized tomography (CBCT). Aluminum, Teflon-PFA (perfluoroalkoxy), and acetal (polyoxymethylene plastic) were selected as materials for the surgical stent. Among these three materials, the appropriate material was chosen using the CBCT images. The surgical stent, which could be easily placed into an oral cavity, was designed with chosen material. CBCT images of the new surgical stent on mandible were obtained using Alphard-3030 dental CT system (Asahi Roentgen Co., Ltd., Kyoto, Japan). The point of insertion was prescribed on the surgical stent with the multiplanar reconstruction software of OnDemand3D (CyberMed Inc., Seoul, Korea). Guide holes were made at the point of insertion on the surgical stent using newly designed guide jig. CBCT scans was taken for the second time to verify the accuracy of the newly designed surgical stent. Teflon-PFA showed radiologically excellent image characteristics for the surgical stent. High accuracy and reproducibility of implantation were confirmed with the surgical stent. The newly designed surgical stent can lead to the accurate implantation and achieve the clinically predictable result.

  9. An experimental study on expandable endovascular metallic stents in dogs

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ho Young; Kim, Hak Nam [Chonbuk National University College of Medicine, Chonju (Korea, Republic of)

    1990-12-15

    We constructed an expandable endovascular metallic stent in the same way as Giamturco did. Experiments were made to test the ability of these stents to be used in the vessels. A total of 20 stents were passed through a 8.5 French teflon sheath into the normal abdominal aorta. IVC, and iliac artery of four adult dogs for 4 weeks to 12 weeks; 8 stents (10 mm in diameter fully expanded and 20 mm in length) in the abnormal aorta, 7 stents (12 mm/20 mm) in the IVC, and 5 stents (8 mm/20 mm) in the iliac artery. All but two stents showed no migration, and one complete occlusion occurred in right iliac artery of a dog. Histologically, stents wires were covered by neo-intimal proliferation. The side branches of the main vessels remained patent, even stent wires across their orifices. These metallic stents may be used as an endovascular graft material in the nonsurgical treatment of several forms of vascular disease.

  10. Expandable metallic stent: experimental and clinical experience in tracheobronchial tree

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ho Young; Lee, Sang Young; Chung, Jin Young; Han, Young Min; Kim, Jong Soo; Choi, Ki Chul; Hong, Ki Whan; Rhee, Yang Kun [Chonbuk National University Medical School, Jeonju (Korea, Republic of)

    1991-05-15

    To maintain or reestablish an adequate airway in a patient with tracheobronchial narrowing coming from various causes, we constructed self-expanding metallic stents the same way Gianturco did, using them in 2 patients after an experimental study with rabbits. Twenty stents (10mm in diameter fully expanded and 20mm in length) were introduced into the trachea or bronchi of 10 Newzealand rabbits (weight, 2.5-3.0kg) through a 8.5 French Teflon sheath. No difficulties were encountered in the placement of the stents. At follow-up (4-12 weeks), no stent showed migration. Three rabbits died of pneumonia or bronchial perforation. Histologically, mucosal inflammation was noted at the sites of stent placement, and stent wires were covered by proliferated epithelium with intact cilia. During the last 4 months, 2 stents were used in 2 patients, one in a patient with endobronchial tuberculosis (3.0cm in length and 1.0cm in diameter fully expanded) and the other (3.0cm in length and 1.5cm in diameter) in a patient with a subglottic mass. In both patients the stents were successfully placed. Just after the placement of the stents dyspnea subsided in both patients, and there was no mortality or morbidity. These stents seem to be effective in the treatment of tracheobronchial stenosis, tracheomalacia, and airway collapse following tracheal reconstruction.

  11. Design Investigation on Applicable Mesh Structures for Medical Stent Applications

    Science.gov (United States)

    Asano, Shoji; He, Jianmei

    2017-11-01

    In recent years, utilization of medical stents is one of effective treatments for stenosis and occlusion occurring in a living body’s lumen indispensable for maintenance of human life such as superficial femoral artery (SFA) occlusion. However, there are concerns about the occurrence of fatigue fractures caused by stress concentrations, neointimal hyperplasia and the like due to the shape structure and the manufacturing method in the conventional stents, and a stent having high strength and high flexibility is required. Therefore, in this research, applicable mesh structures for medical stents based on the design concepts of high strength, high flexibility are interested to solve various problem of conventional stent. According to the shape and dimensions of SFA occlusion therapy stent and indwelling delivery catheter, shape design of the meshed stent are performed using 3-dimensional CAD software Solid Works first. Then analytical examination on storage characteristics and compression characteristics of such mesh structure applied stent models were carried out through finite element analysis software ANSYS Workbench. Meshed stent models with higher strength and higher flexibility with integral molding are investigated analytically. It was found that the storage characteristics and compression characteristics of meshed stent modles are highly dependent on the basic mesh shapes with same surface void ratio. Trade-off relationship between flexibility and storage characteristics is found exited, it is required to provide appropriate curvatures during basic mesh shape design.

  12. Expandable metallic stent: experimental and clinical experience in tracheobronchial tree

    International Nuclear Information System (INIS)

    Song, Ho Young; Lee, Sang Young; Chung, Jin Young; Han, Young Min; Kim, Jong Soo; Choi, Ki Chul; Hong, Ki Whan; Rhee, Yang Kun

    1991-01-01

    To maintain or reestablish an adequate airway in a patient with tracheobronchial narrowing coming from various causes, we constructed self-expanding metallic stents the same way Gianturco did, using them in 2 patients after an experimental study with rabbits. Twenty stents (10mm in diameter fully expanded and 20mm in length) were introduced into the trachea or bronchi of 10 Newzealand rabbits (weight, 2.5-3.0kg) through a 8.5 French Teflon sheath. No difficulties were encountered in the placement of the stents. At follow-up (4-12 weeks), no stent showed migration. Three rabbits died of pneumonia or bronchial perforation. Histologically, mucosal inflammation was noted at the sites of stent placement, and stent wires were covered by proliferated epithelium with intact cilia. During the last 4 months, 2 stents were used in 2 patients, one in a patient with endobronchial tuberculosis (3.0cm in length and 1.0cm in diameter fully expanded) and the other (3.0cm in length and 1.5cm in diameter) in a patient with a subglottic mass. In both patients the stents were successfully placed. Just after the placement of the stents dyspnea subsided in both patients, and there was no mortality or morbidity. These stents seem to be effective in the treatment of tracheobronchial stenosis, tracheomalacia, and airway collapse following tracheal reconstruction

  13. Gianturco-Rösch Z stents in tracheobronchial stenoses.

    Science.gov (United States)

    Petersen, B D; Uchida, B T; Barton, R E; Keller, F S; Rösch, J

    1995-01-01

    To evaluate expandable metallic Gianturco-Rösch Z (GRZ) stents for treatment of benign and malignant tracheobronchial stenoses. Six patients, ages 45-73 years, were treated for severe dyspnea with placement of GRZ stents. Three patients had benign tracheal lesions (one tracheomalacia, two postoperative) and received uncovered GRZ stents. Three patients had malignant stenoses at the level of the carina; one received an uncovered stent and the other two received silicone-covered GRZ stents. Two patients with benign lesions responded well to stent placement. One was asymptomatic for a year and then was lost to follow-up; the other improved substantially but died of end-stage lung disease 5 months after stent placement. A third patient with a benign high tracheal lesion did poorly; symptoms recurred secondary to inferior migration of a stent, which was removed surgically at 4 months. All patients with malignant lesions improved symptomatically after stent placement and remained without significant dyspnea until death (from 1 to 6 months). Expandable GRZ stents are promising devices for treatment of benign lesions and offer effective palliation of malignant tracheobronchial stenoses.

  14. [Drug-eluting stent thrombosis and its pharmacological prevention].

    Science.gov (United States)

    Pershukov, I V; Batyraliev, T A

    2007-01-01

    The problem of drug eluting stents (DES) safety has been actively discussed throughout 2006 because of increase of frequency of development of late stent thromboses which were noted during almost 2 years after stenting. In December 2006 US Food and Drug Administration (FDA) advisory panel acknowledged increase of development of late stent thrombosis. At the same time FDA accepted new definition of stent-thrombosis suggested by the Academic Research Consortium. According to this definition thrombosis can be definite, probable and possible. Any unexplained death before end of follow-up in a trial should be considered thrombosis related. Recalculation of thrombosis rate using this definition caused pronounced increase of this parameter in previously conducted trials. Thrombosis rate rose from 0,6 to 3,3% for bare metal stents, from 0,8 to 3,6% for sirolimus eluting stents and from 1,3 to 3,5% for paclitaxel eluting stents. Professional cardiological and angiographical societies (ACC, AHA, SCAI) responding to FDA advisory panel published their proofs and vision of the problem of stent thrombosis. In February 2007 ACC, AHA, SCAI, American College of Surgeons and Association of Dentists published scientific bulletin in which described preventive measures aimed at lowering of risk of thrombosis development. This document contains strict recommendation to continue double antithrombotic therapy with aspirin and clopidogrel for 12 months after implantation of DES or abandonment of the use of this type of stents when long term double antithrombotic therapy is not possible.

  15. Three-dimensional strutted graphene grown by substrate-free sugar blowing for high-power-density supercapacitors

    Science.gov (United States)

    Wang, Xuebin; Zhang, Yuanjian; Zhi, Chunyi; Wang, Xi; Tang, Daiming; Xu, Yibin; Weng, Qunhong; Jiang, Xiangfen; Mitome, Masanori; Golberg, Dmitri; Bando, Yoshio

    2013-01-01

    Three-dimensional graphene architectures in the macroworld can in principle maintain all the extraordinary nanoscale properties of individual graphene flakes. However, current 3D graphene products suffer from poor electrical conductivity, low surface area and insufficient mechanical strength/elasticity; the interconnected self-supported reproducible 3D graphenes remain unavailable. Here we report a sugar-blowing approach based on a polymeric predecessor to synthesize a 3D graphene bubble network. The bubble network consists of mono- or few-layered graphitic membranes that are tightly glued, rigidly fixed and spatially scaffolded by micrometre-scale graphitic struts. Such a topological configuration provides intimate structural interconnectivities, freeway for electron/phonon transports, huge accessible surface area, as well as robust mechanical properties. The graphene network thus overcomes the drawbacks of presently available 3D graphene products and opens up a wide horizon for diverse practical usages, for example, high-power high-energy electrochemical capacitors, as highlighted in this work. PMID:24336225

  16. Unilateral versus bilateral stent insertion for malignant hilar biliary obstruction.

    Science.gov (United States)

    Chang, Gang; Xia, Feng-Fei; Li, Hong-Fu; Niu, Su; Xu, Yuan-Shun

    2017-11-01

    To determine the clinical efficiency and long-term outcomes between unilateral and bilateral stent insertion in patients with malignant hilar biliary obstruction. From August 2012 to February 2016, 63 consecutive patients with malignant hilar biliary obstruction were treated with unilateral or bilateral stent insertion at our center. The bilateral stents were inserted using the side-by-side technique. The clinical efficiency and long-term outcomes were compared between the two groups. Unilateral and bilateral stent insertions were successfully performed in 31 of 33 and 27 of 30 patients, respectively (P = 0.912). No procedure-related complication occurred. Clinical success was achieved in 29 of 31 patients in the unilateral stent group and in 26 of 27 patients in the bilateral stent group (P = 0.637). During the follow-up, re-obstruction of stent occurred in five patients in the unilateral stent group and in three patients in the bilateral stent group (P = 0.58). The significant differences were not observed in the stent patency time (368 vs. 387 days, P = 0.685) and survival (200 vs. 198 days, P = 0.751) between two groups. Based on the univariate and multivariate analyses, the independent risk factors for decreasing the survival time included higher Eastern Cooperative Oncology Group performance status (P = 0.018), higher alanine aminotransferase level (P = 0.009), and absence of anticancer treatment after stent insertion (P = 0.002). Compared to bilateral stent insertion for malignant hilar biliary obstruction, unilateral stent insertion can provide comparable clinical efficiency and long-term outcomes.

  17. Numerical investigations of the mechanical properties of braided vascular stents.

    Science.gov (United States)

    Fu, Wenyu; Xia, Qixiao; Yan, Ruobing; Qiao, Aike

    2018-01-01

    Braided stents, such as Pipeline Embolization Device (PED; ev3 Neurovascular, Irvine, CA, USA), are commonly used to treat cerebral aneurysms. However, little information is available on the compression and bending characteristics of such stents. This paper investigates how geometrical parameters of braided stents influence their radial compression and bending characteristics. Six groups of braided stent models with different braiding angles, numbers of wires and wire diameters are constructed. Parametric analyses of these models are conducted using Abaqus/Explicit software. The numerical results of a finite element analysis are validated by comparison with data of theoretical analysis. The results show that the radial stiffness is not uniform along the longitudinal direction of the stent. When the braiding angle increases from 30° to 75°, the minimum radial deformation decreases from 0.85 mm to 0.0325 mm (at a pressure of 500 Pa, for 24 braided wires). When the wire diameter increases from 0.026 mm to 0.052 mm, the minimum radial deformation decreases from 0.65 mm to 0.055 mm (at a pressure of 500 Pa and a braiding angle of 60°, for 24 braided wires). Frictions don't affect stent diameter and its axial length when braided stent is crimping, but the friction must be considered when it is related to the radial pressure required for compression the braided stent. Compared with commonly used intracranial stents, a braided stent with geometrical parameters close to PED stent has a smaller radial stiffness but a considerably greater longitudinal flexibility. The results of this analysis of braided stents can help in the design and selection of flow diverter stents for clinical treatment of cerebral aneurysms.

  18. 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

  19. 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.

  20. Ferromagnetic Bare Metal Stent for Endothelial Cell Capture and Retention.

    Science.gov (United States)

    Uthamaraj, Susheil; Tefft, Brandon J; Hlinomaz, Ota; Sandhu, Gurpreet S; Dragomir-Daescu, Dan

    2015-09-18

    Rapid endothelialization of cardiovascular stents is needed to reduce stent thrombosis and to avoid anti-platelet therapy which can reduce bleeding risk. The feasibility of using magnetic forces to capture and retain endothelial outgrowth cells (EOC) labeled with super paramagnetic iron oxide nanoparticles (SPION) has been shown previously. But this technique requires the development of a mechanically functional stent from a magnetic and biocompatible material followed by in-vitro and in-vivo testing to prove rapid endothelialization. We developed a weakly ferromagnetic stent from 2205 duplex stainless steel using computer aided design (CAD) and its design was further refined using finite element analysis (FEA). The final design of the stent exhibited a principal strain below the fracture limit of the material during mechanical crimping and expansion. One hundred stents were manufactured and a subset of them was used for mechanical testing, retained magnetic field measurements, in-vitro cell capture studies, and in-vivo implantation studies. Ten stents were tested for deployment to verify if they sustained crimping and expansion cycle without failure. Another 10 stents were magnetized using a strong neodymium magnet and their retained magnetic field was measured. The stents showed that the retained magnetism was sufficient to capture SPION-labeled EOC in our in-vitro studies. SPION-labeled EOC capture and retention was verified in large animal models by implanting 1 magnetized stent and 1 non-magnetized control stent in each of 4 pigs. The stented arteries were explanted after 7 days and analyzed histologically. The weakly magnetic stents developed in this study were capable of attracting and retaining SPION-labeled endothelial cells which can promote rapid healing.

  1. In vitro pharmacokinetics of sirolimus-coated stent for tracheal stenosis

    African Journals Online (AJOL)

    Further increases in sirolimus: PLGA ratio did not improve stent drug loading. A slow release of ... tracheal stent can damage the airway mucosa, and cause .... Figure 3: Cumulative drug release from sirolimus-coated stents. DISCUSSION.

  2. Comparison of diamond-like carbon-coated nitinol stents with or without polyethylene glycol grafting and uncoated nitinol stents in a canine iliac artery model

    Science.gov (United States)

    Kim, J H; Shin, J H; Shin, D H; Moon, M-W; Park, K; Kim, T-H; Shin, K M; Won, Y H; Han, D K; Lee, K-R

    2011-01-01

    Objective Neointimal hyperplasia is a major complication of endovascular stent placement with consequent in-stent restenosis or occlusion. Improvements in the biocompatibility of stent designs could reduce stent-associated thrombosis and in-stent restenosis. We hypothesised that the use of a diamond-like carbon (DLC)-coated nitinol stent or a polyethylene glycol (PEG)-DLC-coated nitinol stent could reduce the formation of neointimal hyperplasia, thereby improving stent patency with improved biocompatibility. Methods A total of 24 stents were implanted, under general anaesthesia, into the iliac arteries of six dogs (four stents in each dog) using the carotid artery approach. The experimental study dogs were divided into three groups: the uncoated nitinol stent group (n = 8), the DLC-nitinol stent group (n = 8) and the PEG-DLC-nitinol stent group (n = 8). Results The mean percentage of neointimal hyperplasia was significantly less in the DLC-nitinol stent group (26.7±7.6%) than in the nitinol stent group (40.0±20.3%) (p = 0.021). However, the mean percentage of neointimal hyperplasia was significantly greater in the PEG-DLC-nitinol stent group (58.7±24.7%) than in the nitinol stent group (40.0±20.3%) (p = 0.01). Conclusion Our findings indicate that DLC-coated nitinol stents might induce less neointimal hyperplasia than conventional nitinol stents following implantation in a canine iliac artery model; however, the DLC-coated nitinol stent surface when reformed with PEG induces more neointimal hyperplasia than either a conventional or DLC-coated nitinol stent. PMID:21325363

  3. Retreatment of recanalized aneurysms after Y-stent-assisted coil embolization with double enterprise stents: case report and systematic review of the literature.

    Science.gov (United States)

    Kono, Kenichi; Shintani, Aki; Terada, Tomoaki

    2014-01-01

    It is necessary to consider possibility of recanalization and retreatment after coil embolization for cerebral aneurysms. There is concern that retreatment for recanalized aneurysms after Y-stent-assisted coil embolization may be difficult because of double stents, especially in Y-stents with double closed-cell stents owing to narrowed structures. However, no detailed reports of retreatment after Y-stent have been reported. Between July 2010 and June 2013, we treated four aneurysms with Y-stent-assisted coil embolization using Enterprise closed-cell stents. Recanalization occurred in one case (25%), and retreatment was performed. We easily navigated a microcatheter into the target portions of the aneurysm through the Y-stent and occluded the aneurysm with coils. Additionally, by systematically searching in PubMed, we found 105 cases of Y-stent-assisted coil embolization using Enterprise stents or Neuroform stents with more than 6 months of follow-up. Among them, retreatment was performed in 10 cases (9.5%). There were no significant differences in retreatment rates among different stent combinations (P=0.91; Fisher's exact test). In conclusion, navigation of a microcatheter into the aneurysm through the Y-stent with double Enterprise stents was feasible, and retreatment rates after Y-stent-assisted coiling may not depend on stent combinations.

  4. Comparison of closed-cell and hybrid-cell stent designs in carotid artery stenting: clinical and procedural outcomes

    Directory of Open Access Journals (Sweden)

    Ersan TatlI

    2017-05-01

    Full Text Available Introduction: Carotid artery stenting (CAS is a promising alternative to surgery in high-risk patients. However, the impact of stent cell design on outcomes in CAS is a matter of continued debate. Aim : To compare the periprocedural and clinical outcomes of different stent designs for CAS with distal protection devices. Material and methods : All CAS procedures with both closed- and hybrid-cell stents performed at our institution between February 2010 and December 2015 were analyzed retrospectively. Adverse events were defined as death, major stroke, minor stroke, transient ischemic attack and myocardial infarction. Periprocedural and 30-day adverse events and internal carotid artery (ICA vasospasm rates were compared between the closed-cell and hybrid-cell stent groups. Results : The study included 234 patients comprising 146 patients with a closed-cell stent (Xact stent, Abbott Vascular (mean age: 68.5 ±8.6; 67.1% male and 88 patients with a hybrid-cell stent (Cristallo Ideale, Medtronic (mean age: 67.2 ±12.8; 68.2% male. There was no significant difference between the groups with respect to periprocedural or 30-day adverse event rates. While there was no difference in terms of tortuosity index between the groups, there was a higher procedural ICA vasospasm rate in the closed-cell stent group (35 patients, 23% compared with the hybrid-cell stent group (10 patients, 11% (p = 0.017. Conclusions : The results of this study showed no significant difference in the clinical adverse event rates after CAS between the closed-cell stent group and the hybrid-cell stent group. However, procedural ICA vasospasm was more common in the closed-cell stent group.

  5. Novel 3D-CT evaluation of carotid stent volume: greater chronological expansion of stents in patients with vulnerable plaques.

    Science.gov (United States)

    Itami, Hisakazu; Tokunaga, Koji; Okuma, Yu; Hishikawa, Tomohito; Sugiu, Kenji; Ida, Kentaro; Date, Isao

    2013-09-01

    Although self-expanding carotid stents may dilate gradually, the degrees of residual stenosis have been quantified by the NASCET criteria, which is too simple to reflect the configuration of the stented artery. We measured the volumes of the stent lumens chronologically by 3D-CT in patients after carotid artery stenting (CAS), and analyzed the correlations between the volume change and medical factors. Fourteen patients with carotid artery stenosis were treated using self-expanding, open-cell stents. All patients underwent preoperative plaque MRI (magnetization-prepared rapid acquisition gradient-echo, MPRAGE) and chronological 3D-CT examinations of their stents immediately after their placement and 1 day, 1 week, and 1 month after the procedure. The volume of the stent lumen was measured using a 3D workstation. The correlations between stent volume and various factors including the presence of underlying diseases, plaque characteristics, and the results of the CAS procedure were analyzed. Stent volume gradually increased in each case and had increased by 1.04-1.55 (mean, 1.25)-fold at 1 postoperative month. The presence of underlying medical diseases, plaque length, the degree of residual stenosis immediately after CAS, and plaque calcification did not have an impact on the change in stent volume. On the other hand, the stent volume increase was significantly larger in the patients with vulnerable plaques that demonstrated high MPRAGE signal intensity (P stent volume. Self-expanding stents in carotid arteries containing vulnerable plaques expand significantly more than those without such plaques in a follow-up period.

  6. 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.

  7. Stent thrombosis with drug-eluting and bare-metal stents: evidence from a comprehensive network meta-analysis.

    Science.gov (United States)

    Palmerini, Tullio; Biondi-Zoccai, Giuseppe; Della Riva, Diego; Stettler, Christoph; Sangiorgi, Diego; D'Ascenzo, Fabrizio; Kimura, Takeshi; Briguori, Carlo; Sabatè, Manel; Kim, Hyo-Soo; De Waha, Antoinette; Kedhi, Elvin; Smits, Pieter C; Kaiser, Christoph; Sardella, Gennaro; Marullo, Antonino; Kirtane, Ajay J; Leon, Martin B; Stone, Gregg W

    2012-04-14

    The relative safety of drug-eluting stents and bare-metal stents, especially with respect to stent thrombosis, continues to be debated. In view of the overall low frequency of stent thrombosis, large sample sizes are needed to accurately estimate treatment differences between stents. We compared the risk of thrombosis between bare-metal and drug-eluting stents. For this network meta-analysis, randomised controlled trials comparing different drug-eluting stents or drug-eluting with bare-metal stents currently approved in the USA were identified through Medline, Embase, Cochrane databases, and proceedings of international meetings. Information about study design, inclusion and exclusion criteria, sample characteristics, and clinical outcomes was extracted. 49 trials including 50,844 patients randomly assigned to treatment groups were analysed. 1-year definite stent thrombosis was significantly lower with cobalt-chromium everolimus eluting stents (CoCr-EES) than with bare-metal stents (odds ratio [OR] 0·23, 95% CI 0·13-0·41). The significant difference in stent thrombosis between CoCr-EES and bare-metal stents was evident as early as 30 days (OR 0·21, 95% CI 0·11-0·42) and was also significant between 31 days and 1 year (OR 0·27, 95% CI 0·08-0·74). CoCr-EES were also associated with significantly lower rates of 1-year definite stent thrombosis compared with paclitaxel-eluting stents (OR 0·28, 95% CI 0·16-0·48), permanent polymer-based sirolimus-eluting stents (OR 0·41, 95% CI 0·24-0·70), phosphorylcholine-based zotarolimus-eluting stents (OR 0·21, 95% CI 0·10-0·44), and Resolute zotarolimus-eluting stents (OR 0·14, 95% CI 0·03-0·47). At 2-year follow-up, CoCr-EES were still associated with significantly lower rates of definite stent thrombosis than were bare-metal (OR 0·35, 95% CI 0·17-0·69) and paclitaxel-eluting stents (OR 0·34, 95% CI 0·19-0·62). No other drug-eluting stent had lower definite thrombosis rates compared with bare

  8. Endeavour zotarolimus-eluting stent reduces stent thrombosis and improves clinical outcomes compared with cypher sirolimus-eluting stent : 4-year results of the PROTECT randomized trial

    NARCIS (Netherlands)

    Wijns, William; Steg, Ph. Gabriel; Mauri, Laura; Kurowski, Volkhard; Parikh, Keyur; Gao, Runlin; Bode, Christoph; Greenwood, John P.; Lipsic, Erik; Alamgir, Farqad; Rademaker-Havinga, Tessa; Boersma, Eric; Radke, Peter; van Leeuwen, Frank; Camenzind, Edoardo

    2014-01-01

    Aims To compare the long-term clinical safety between two drug-eluting stents with different healing characteristics in the Patient Related Outcomes with Endeavour (E-ZES) vs. Cypher (C-SES) Stenting Trial (PROTECT). At 3 years, there was no difference in the primary outcome of definite or probable

  9. Treatment of hilar cholangiocarcinoma with inserting biliary double stents

    International Nuclear Information System (INIS)

    Jia Guangzhi; Zhang Zidong; Wang Xuejing; Yin Hua; Li Jianming

    2004-01-01

    Objective: To investigate the inserting technique of biliary double stents in treating hilar cholangiocarcinoma. Methods: 6 patients with hilar cholangiocarcinoma (Bismuth IV) were treated by percutaneous transhepatic insertion of biliary stents. Double stents were inserted in each patient. Different inserting methods were adopted according to the branch angles formed by left and right hepatic ducts. Results: The jaundice of all patients alleviated or disappeared obviously after stent implantation. The average difference between post-and pre-operation in the serum total bilirubin level was (104 ± 29) μmol/L (P<0.01). Stent obstruction was found in 2 cases after 4 and 6 months respectively. Conclusion: Double stents implantation is effective for the treatment of hilar cholangiocarcinoma. Beware of the angulation between main hepatic duct and adopting different inserting methods. (authors)

  10. 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.

  11. Esophageal stent migration can lead to intestinal obstruction

    Science.gov (United States)

    Karatepe, Oguzhan; Acet, Ersin; Altiok, Merih; Battal, Muharrem; Adas, Gokhan; Karahan, Servet

    2009-01-01

    Background: Self-expanding metallic stents are the devices of choice in the treatment of malign or benign strictures of the 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 operations and esophageal stent applications, was admitted to our emergency department with a 48-hour history of abdominal pain, nausea and vomiting. An emergency laparotomy was performed and the migrated stent causing 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. PMID:22666672

  12. Percutaneous antegrade ureteric stent removal using a rigid alligator forceps.

    LENUS (Irish Health Repository)

    Given, M F

    2008-12-01

    To evaluate the safety and efficacy of percutaneous antegrade ureteric stent removal using a rigid alligator forceps. Twenty patients were included in our study. Indications for ureteric stent insertion included stone disease (n = 7), malignancy (n = 8) and transplant anastomotic strictures (n = 5). Stent retrieval was carried out for proximal stent placement\\/migration in seven patients and encrustation in the remaining 13. Twenty-two stents were successfully retrieved in 20 patients. There was one technical failure (5%). There were no major complications. We had four minor complications, which included nephrostomy site pain (n = 2), periprocedural sepsis (n = 1) and a small urinoma (n = 1). All patients settled with conservative management. Percutaneous radiologically guided antegrade ureteric stent removal with an alligator forceps is safe and effective, particularly when initial surgical removal has failed.

  13. Post-biliary sphincterotomy bleeding despite covered metallic stent deployment

    Directory of Open Access Journals (Sweden)

    Gianfranco Donatelli

    2016-05-01

    Full Text Available Objectives: Several endoscopic techniques have been proposed for the management of post-sphincterotomy bleeding. Lately, self-expandable metal stents deployment has gained popularity especially as a rescue therapy when other endoscopic techniques fail. Methods-results: We report the case report of a massive post-sphincterotomy bleeding in a patient with a self-expandable metal stent in the biliary tree. Despite the presence of a correctly positioned self-expandable metal stent, a new endoscopic session was required to control the bleeding. Conclusions: Self-expandable metal stent may be useful to manage post-endoscopic sphincterotomy bleeding. However, up to now there is no specifically designed self-expandable metal stent for such complication. Large new designed self-expandable metal stent may be a useful tool for biliary endoscopist.

  14. Influence of a pressure gradient distal to implanted bare-metal stent on in-stent restenosis after percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Jensen, Lisette Okkels; Thayssen, Per; Thuesen, Leif

    2007-01-01

    pullback recording in the entire length of the artery. METHODS AND RESULTS: In 98 patients with angina pectoris, 1 de novo coronary lesion was treated with a bare-metal stent. After stent implantation, pressure wire measurements (P(d)=mean hyperemic coronary pressure and P(a)=mean aortic pressure) were......-stent restenosis after 9 months. CONCLUSIONS: A residual abnormal P(d)/P(a) distal to a bare-metal stent was an independent predictor of in-stent restenosis after implantation of a coronary bare-metal stent. Udgivelsesdato: 2007-Dec-11......BACKGROUND: Fractional flow reserve predicts cardiac events after coronary stent implantation. The aim of the present study was to assess the 9-month angiographic in-stent restenosis rate in the setting of optimal stenting and a persisting gradient distal to the stent as assessed by a pressure wire...

  15. 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.

  16. A comparison of clinical efficacy between covered stent-grafts and bare stents in transjuglar in-trahepatic portosystemic shunt

    International Nuclear Information System (INIS)

    Jiang Yongbin; Zhang Xitong; Zhang Wei; Xia Yonghui; Liang Songnian; Xu Ke

    2010-01-01

    Objective: To compare the clinical efficacy between covered stent and uncovered stent in transjuglar in-trahepatic portosystemic shunt (TIPS). Methods: Thirty patients with liver cirrhosis (portal hypertension), who received TIPS, were retrospectively studied. All patients were divided into two groups covered-stent group (n=20) and uncovered-stent group (n=10). For each patient, portal pressure was measured before and after operation, and the patency of shunt was evaluated by color Doppler ultrasound after operation. The mortality, recurrent bleeding rate and incidence of hepatic encephalopathy were analyzed by Fisher exact probability test. Results: The TIPS treatment was successful in all patients, the portal pressure in the covered-stent group reduced from (3.78 ± 0.50)kPa to (2.13 ± 0.44) kPa and that of the uncovered-stent group reduced from (3.67 ± 0.48)kPA TO (2.13 ± 0.35)kPa. Twenty-six cases were postoperatively followed-up (17 cases in covered-stent group, 9 cases in uncovered-stent group). the follow-up period varied from 7 days to 62 months (median follow-up period was 23 months). Thirteen patients died of upper gastrointestinal bleeding and hepatic failure. The difference of mortality between covered-stent group (8/17) and uncovered-stent group (5/17) and the uncovered-stent group (3/9) was not different too (P>0.05). The incidence of hepatic encephalopathy in the covered-stent group (4/17) was not different from that of the uncovered-stent group (2/9) (P>0.05). The patency rates of 6 months and 12 months reached 100% in the covered-stent group, which were higher than those in the uncovered-stent group 77.8% (7/9) and 55.6%(5/9) (P<0.05). Conclusions: The patency rate of shunt at 12 months after TIPS was higher in the covered-stent group than the uncovered-stent group, while the mortality, recurrent bleeding rate and incidence of hepatic encephalopathy were not significantly different between the two groups. (authors)

  17. Revisiting the tethered ureteral stents in children: a novel modification.

    Science.gov (United States)

    Kajbafzadeh, Abdol-Mohammad; Nabavizadeh, Behnam; Keihani, Sorena; Hosseini Sharifi, Seyed Hossein

    2015-06-01

    To propose a simple noninvasive method for ureteral stent retrieval using an extraction string sutured to the skin in children. A retrospective chart review was performed to gather relevant data from December 2005 to February 2013. After the surgeries, if indicated, a tethered double-J stent was placed in the ureter. A 5-0 non-absorbable Prolene stitch was used as an extraction string passing through the urethra and was sutured to subcoronal skin in boys or inner surface of labia majora in girls. For stent removal, a small amount of 2 % lidocaine jelly was pushed into the urethra 5 min before the procedure. The string was then pulled by continuous and gentle force until the entire stent was out. The suture was then cut to release the stent. No sedation or anesthesia was needed. A total of 378 double-J stents with extraction strings were inserted for a total of 325 patients (61.2 % male). Of the 53 patients with bilateral ureteral stents, one male patient (1.88 %) experienced early stent protrusion from urethral meatus. Two of 272 patients (0.73 %) with unilateral ureteral stent (one male and one female) encountered the same problem. All other stents were extracted successfully using the extraction string without any complications. No upward stent migration or suture site reaction was encountered. This method is a safe, easy-to-use, feasible and noninvasive alternative for cystoscopic stent removal with high success rate and minimal complications. This can lead to considerable saving in time and costs for patients, families and healthcare system.

  18. [Evaluation of stents in treating childhood benign esophageal strictures].

    Science.gov (United States)

    Reinshagen, K; Kähler, G; Manegold, B C; Waag, K-L

    2009-01-01

    Esophageal stenting is a popular of treatment of esophageal strictures in adults. It has also been described for children with benign strictures who did not respond to standard dilatation therapy. The aim of the study was to evaluate weather esophageal stents could be used safely and effectively in the treatment of benign esophageal strictures in children. From 1993 to 2005 stenting therapy was performed in 12 children with complicated esophageal strictures. Etiologies of the strictures were caustic burns in 9 patients, postoperative strictures due to complicated esophageal atresia in 2 patients and iatrogenic esophageal injury in 1 patient. Esophageal silicon tubi, covered retrievable expandable nitinol and plastic stents were placed endoscopically. The clinical course and the long term follow up were evaluated retrospectively The stents and tubi were placed in all patients without complications and were later removed successfully. 6 patients were treated with a self expanding plastic stent. The plastic stents showed a distinct tendency to migrate but in 5/6 patients esophageal stricture was treated successfully. 3 patients were treated by a covered self expanding nitinol stent. No migration occurred. One patient was asymptomatic after therapy, one required further dilatation therapy and the third had esophageal resection. 3 patients were treated by esophageal tubi. 2 patients required surgery in the follow up, one patient is asymptomatic. The use of stenting devices in children to treat benign esophageal strictures is safe and efficient. The self expanding plastic stents had the best long term results but required high compliance of parents and children due to the tendency of stent migration. Self expanding nitinol stents are more traumatic at the extraction procedure and are useful in patients with low compliance. Recurrence of strictures occurred most often after esophageal tubi possibly due to the lack of radial expansion.

  19. 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....

  20. Endoscopically placed nitinol stents for pediatric tracheal obstruction.

    Science.gov (United States)

    Prasad, Mukesh; Bent, John P; Ward, Robert F; April, Max M

    2002-11-11

    To provide preliminary clinical data regarding endoscopically placed nitinol stents for children with tracheal obstruction as a temporizing measure to allow for trach tube decannulation while awaiting growth to allow for tracheal resection. This case series describes the experiences of two children (ages 5 and 15) who were dependent upon tracheotomy because of acquired tracheal obstruction. Both patients had combined tracheomalacia and tracheal stenosis. After failing tracheoplasty with rib graft augmentation both patients suffered from extensive tracheal disease, which was too long to allow for immediate tracheal resection. Endoscopic placement of nitinol stents in the obstructed tracheal segment using fluoroscopic guidance. All tracheotomy tubes were removed immediately after successful stent deployment with the patient still under general anesthesia. Four stents were placed in total. The first patient's initial stent was too narrow and was, therefore, removed and replaced at a later date with a larger diameter stent. The second patient experienced distal migration of his initial stent requiring stent removal and replacement at a later date. Both patients remain successfully decannulated (follow-up, 25 and 26 months) and are currently living more normal lives as they grow and await tracheal resection. Preliminary use of nitinol stents for pediatric tracheal obstruction has enabled successful decannulation in two children with complicated airways. Our results with this series of patients suggest that nitinol stents can be safely used in children as a temporizing measure until tracheal resection can be safely performed. With this approach children can live free from the hassles of trach care, social isolation and peer ridicule. Limited pediatric experience exists in the literature about nitinol stents. Thus, our experience with stent selection and placement will help others avoid problems encountered in this initial series. Copyright 2002 Elsevier Science Ireland