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

PubMed

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

Ureteral Stent Coatings: What's Here and What's Coming

NASA Astrophysics Data System (ADS)

Razvi, Hassan

2008-09-01

Ureteral stents have become an indispensable tool to the urologist in the management of various disorders afflicting the urinary tract. While the ideal stent remains elusive, novel technical advances in stent coating technology offer the potential of enhancing stent biocompatibility and clinical application. Currently available stent coatings as well as new and emerging devices will be reviewed.

A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications

PubMed Central

Park, Jongsung; Kim, Ji-Kwan; Patil, Swati J.; Park, Jun-Kyu; Park, SuA; Lee, Dong-Weon

2016-01-01

This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm2 and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone) stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent. PMID:27271619

A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications.

PubMed

Park, Jongsung; Kim, Ji-Kwan; Patil, Swati J; Park, Jun-Kyu; Park, SuA; Lee, Dong-Weon

2016-06-02

This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm² and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone) stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent.

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

PubMed

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.

Current Status of the Application of Intracranial Venous Sinus Stenting

PubMed Central

Xu, Kan; Yu, Tiecheng; Yuan, Yongjie; Yu, Jinlu

2015-01-01

The intracranial venous sinus is an important component of vascular disease. Many diseases involve the venous sinus and are accompanied by venous sinus stenosis (VSS), which leads to increased venous pressure and high intracranial pressure. Recent research has focused on stenting as a treatment for VSS related to these diseases. However, a systematic understanding of venous sinus stenting (VS-Stenting) is lacking. Herein, the literature on idiopathic intracranial hypertension (IIH), venous pulsatile tinnitus, sinus thrombosis, high draining venous pressure in dural arteriovenous fistula (AVF) and arteriovenous malformation (AVM), and tumor-caused VSS was reviewed and analyzed to summarize experiences with VS-Stenting as a treatment. The literature review showed that satisfactory therapeutic effects can be achieved through stent angioplasty. Thus, the present study suggests that selective stent release in the venous sinus can effectively treat these diseases and provide new possibilities for treating intracranial vascular disease. PMID:26516306

Indications and applications of arterial stents for stroke prevention in atherosclerotic intracranial stenosis.

PubMed

Fields, Jeremy D; Liu, Kenneth C; Barnwell, Stanley L; Clark, Wayne M; Lutsep, Helmi L

2010-01-01

Intracranial stenosis accounts for 8-10% of all ischemic strokes in North America, a frequency slightly less than that of extracranial carotid stenosis. Among patients presenting with transient ischemic attack or stroke due to intracranial stenosis, the risk of recurrent stroke in the first year after initial symptoms is about 14%. Those with high-risk features (recent stroke and severe stenosis) have up to a 23% rate of recurrent stroke in the year after their initial event. Angioplasty with stenting has emerged as a potential treatment strategy, particularly in high-risk patients, although evidence is currently limited to uncontrolled prospective trials and retrospective case series. In this article, we critically review the clinical results supporting the use of stenting and highlight some key considerations in the application of this technology, including patient selection, procedural management, technical issues, and risk factors for complications and in-stent restenosis.

Combined use of videoendoscopy and X-ray imaging for improved monitoring of stenting application

NASA Astrophysics Data System (ADS)

Cysewska-Sobusiak, A. R.; Sowier, A.; Skrzywanek, P.

2005-09-01

The subject of this paper concerns advanced techniques of procedures and imaging used in minimally invasive surgery and in non-operable cases of the alimentary tract tumor therapy. Examples of videoendoscopy and X-ray imaging used for the application of stents (prostheses) and catheters allowing for the performance of diagnostic and endo-therapeutic procedures are described. The possibility was indicated to elaborate a new method of proceeding in tumor therapy in the patients for whom the methods used so far were ineffective. In the paper examples of combined imaging the application of metallic stents and plastic catheters allowing for the performance of diagnostic and therapeutic procedures are presented. The cases shown refer to tumor located in the esophagus and in the bile and pancreatic ducts.

Novel biliary self-expanding metal stents: indications and applications.

PubMed

Blero, Daniel; Huberty, Vincent; Devière, Jacques

2015-03-01

Endoscopic insertion of a self-expanding metal stent (SEMS) through a malignant common bile duct stricture is the first line of palliation for malignant jaundice. Patency of these stents remains a major concern. SEMS dysfunction can result from tumor ingrowth, overgrowth and/or clogging. Initial SEMS modifications involved covering the central part of the stent in order to reduce ingrowth and ultimately increase patency. Fully covered stents became available shortly after reports of their use in human patients. The potential removability and radial strength of SEMS have led to evaluation of their use in new indications including benign biliary strictures, post sphincterotomy bleeding and perforation. Other aspects of development include the addition of features such as anti-reflux valves, drug elution and spontaneous biodegradability. These aspects and their clinical implications are reviewed and discussed.

Stents for colorectal obstruction: Past, present, and future

PubMed Central

Kim, Eui Joo; Kim, Yoon Jae

2016-01-01

Since the development of uncovered self-expanding metal stents (SEMS) in the 1990s, endoscopic stents have evolved dramatically. Application of new materials and new designs has expanded the indications for enteral SEMS. At present, enteral stents are considered the first-line modality for palliative care, and numerous types of enteral stents are under development for extended clinical usage, beyond a merely palliative purpose. Herein, we will discuss the current status and the future development of lower enteral stents. PMID:26811630

Dilatation by Soehendra stent retriever is feasible and effective in multiple deployment of metallic stents to malignant hilar biliary strictures.

PubMed

Kato, Hironari; Kawamoto, Hirofumi; Noma, Yasuhiro; Sonoyama, Takayuki; Tsutsumi, Koichiro; Fujii, Masakuni; Okada, Hiroyuki; Yamamoto, Kazuhide

2013-01-01

The endoscopic management of malignant hilar biliary strictures using multiple metallic stents (MS) is technically demanding, in the initial deployment of MS and the recovery from MS occlusion with deployment of multiple plastic stents (PS). We evaluated the outcomes of the application of a Soehendra stent retriever (SSR) as a dilator of intractable strictures. Fifty-nine patients with malignant hilar biliary strictures had multiple MS inserted using a partial stent-in-stent procedure. When we encountered intractable strictures, we adopted SSR to dilate the stricture and the interstice of the MS. We evaluated the success rate of MS or PS deployment after SSR application and procedural complications. Five of 59 patients (8%) were subjected to SSR application for the initial MS deployment. MS were successfully deployed in all of these patients (100%). MS occlusion was noted in 27 patients. We applied SSR to seven patients (26%) for the deployment of multiple PS after MS occlusion. In five patients (71%), successful PS deployment was achieved after the SSR application. No complications related to dilatation using SSR occurred in any patient. SSR proved to be a potent dilator of difficult strictures in the management of malignant hilar biliary strictures.

Fatigue and durability of Nitinol stents.

PubMed

Pelton, A R; Schroeder, V; Mitchell, M R; Gong, Xiao-Yan; Barney, M; Robertson, S W

2008-04-01

Nitinol self-expanding stents are effective in treating peripheral artery disease, including the superficial femoral, carotid, and renal arteries. However, fracture occurrences of up to 50% have been reported in some stents after one year. These stent fractures are likely due to in vivo cyclic displacements. As such, the cyclic fatigue and durability properties of Nitinol-based endovascular stents are discussed in terms of an engineering-based experimental testing program. In this paper, the combined effects of cardiac pulsatile fatigue and stent-vessel oversizing are evaluated for application to both stents and stent subcomponents. In particular, displacement-controlled fatigue tests were performed on stent-like specimens processed from Nitinol microtubing. Fatigue data were collected with combinations of simulated oversizing conditions and pulsatile cycles that were identified by computer modeling of the stent that mimic in vivo deformation conditions. These data are analyzed with non-linear finite element computations and are illustrated with strain-life and strain-based constant-life diagrams. The utility of this approach is demonstrated in conjunction with 10 million cycle pulsatile fatigue tests of Cordis SMART Control((R)) Nitinol self-expanding stents to calculate fatigue safety factors and thereby predict in vivo fatigue resistance. These results demonstrate the non-linear constant fatigue-life response of Nitinol stents, whereby, contrary to conventional engineering materials, the fatigue life of Nitinol is observed to increase with increasing mean strain.

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

PubMed

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.

The current role of vascular stents.

PubMed

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.

Predictors of early stent occlusion among plastic biliary stents.

PubMed

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.

A practical method to rapidly dissolve metallic stents.

PubMed

Bradshaw, Scott H; Kennedy, Lloyd; Dexter, David F; Veinot, John P

2009-01-01

Metallic stents are commonly used in many clinical applications including peripheral vascular disease intervention, biliary obstruction, endovascular repair of aneurysms, and percutaneous coronary interventions. In the examination of vascular stent placement, it is important to determine if the stent is open or has become obstructed. This is increasingly important in the era of drug-eluting stent usage in coronary arteries. We describe a practical, rapid and cost-effective method to dissolve most metallic stents leaving the vascular and luminal tissues intact. This practical method may replace the laborious and expensive plastic embedding methods currently utilized.

Carotid Artery Stenting Using a Novel Self-Expanding Braided Nickel-Titanium Stent: Feasibility and Safety Porcine Trial

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahlhelm, Frank, E-mail: frah1@gmx.de; Kaufmann, Ralf, E-mail: ralf.kaufmann@vascomed.d; Ahlhelm, Dirk, E-mail: ahlhelmd@gmx.de

We studied the deliverability and safety of a braided, self-expanding, closed-cell nickel-titanium (NiTi) stent (E-volution, Jotec GmbH, Hechingen, Germany) especially designed for the endovascular treatment of carotid artery bifurcation stenosis with special regard to in-stent stenosis and thrombosis compared with a laser-cut reference nitinol stent in a porcine model of percutaneous vascular interventions. We aimed to assess histopathologic response in minipig carotid and subclavian arteries. Eight minipigs received a total of 42 stents: 14 reference stents and 28 E-volution stents. Eleven of the E-volution stents were additionally coated with heparin. Control angiography was obtained immediately before and after vascular interventionmore » as well as 4 weeks after the procedure. Primary endpoints were 28 days of angiographic analyses as well as histomorphometric analysis, including injury score, inflammation score, luminal diameter, vessel diameter, maximal neointimal thickness, and area of in-stent stenosis. Secondary end points were procedural success, 28-day mortality, and stent thrombosis. All stents could be delivered successfully without procedural complications, morbidity, or mortality during our observation time. As confirmed by histology, no in-stent thrombosis was observed. Compared with common carotid arteries, subclavian arteries are significantly more vulnerable to developing in-stent stenosis caused by neointima proliferation (p < 0.05). Compared with the use of 1 single stent/artery, serial application of two stents leads to a more excessive but not significantly different neointimal proliferation (p > 0.05). The E-volution stent, especially when heparin coated, is in line with the comparison to the laser-cut reference stent displaying similar results of angiographic, histologic, and histomorphometric analyses (p > 0.05). Compared with the reference laser-cut stent, the self-expanding nitinol stent (E-volution) with its advanced braiding

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

PubMed

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.

Mechanical Properties of High Entropy Alloy Al0.1CoCrFeNi for Peripheral Vascular Stent Application.

PubMed

Alagarsamy, Karthik; Fortier, Aleksandra; Komarasamy, Mageshwari; Kumar, Nilesh; Mohammad, Atif; Banerjee, Subhash; Han, Hai-Chao; Mishra, Rajiv S

2016-12-01

High entropy alloys (HEAs) are new class of metallic materials with five or more principal alloying elements. Due to this distinct concept of alloying, the HEAs exhibit unique properties compared to conventional alloys. The outstanding properties of HEAs include increased strength, superior wear resistance, high temperature stability, increased fatigue properties, good corrosion, and oxidation resistance. Such characteristics of HEAs have generated significant interest among the scientific community. However, their applications are yet to be explored. This paper discusses the mechanical behavior and microstructure of Al 0.1 CoCrFeNi HEA subjected to thermo-mechanical processing, and its potential application in peripheral vascular stent implants that are prone to high failure rates. Results show that Al 0.1 CoCrFeNi alloy possesses characteristics that compare well against currently used stent materials and it can potentially find use in peripheral vascular stent implants and extend their life-cycle.

Expandable stents.

PubMed

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

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

PubMed

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.

Magnetizable stent-grafts enable endothelial cell capture

NASA Astrophysics Data System (ADS)

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.

Magnetizable stent-grafts enable endothelial cell capture.

PubMed

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.

Correction of Stent Distortion and Overhanging Stent Struts during Left Main Bifurcation Stenting by Selective Distal Stent Cell Re-Wiring: A Novel Guidewire Approach

PubMed Central

Sabbah, Mahmoud; Kadota, Kazushige; Fuku, Yasushi; Mitsudo, Kazuaki

2015-01-01

Stent malapposition and overhanging stent struts in front of the side branch (SB) ostium are not uncommon following bifurcation stenting that might lead to stent thrombosis. We herein present 2 cases, in which optical frequency domain imaging and intravascular ultrasound effectively revealed stent malapposition and overhanging struts inside the ostium of the SB following left main coronary artery stenting. Therefore, we introduced a novel technique for rectification of these incidental findings by selective SB re-wiring through the most distal stent cell with the adjunctive help of a double lumen microcatheter. PMID:27122906

Neurovascular stent artifacts in 3D-TOF and 3D-PCMRI: Influence of stent design on flow measurement.

PubMed

Bouillot, Pierre; Brina, Olivier; Delattre, Bénédicte M A; Ouared, Rafik; Pellaton, Alain; Yilmaz, Hasan; Machi, Paolo; Lovblad, Karl-Olof; Farhat, Mohamed; Pereira, Vitor Mendes; Vargas, Maria Isabel

2018-06-12

The morphological and hemodynamic evaluations of neurovascular diseases treated with stents would benefit from noninvasive imaging techniques such as 3D time-of-flight MRI (3D-TOF) and 3D phase contrast MRI (3D-PCMRI). For this purpose, a comprehensive evaluation of the stent artifacts and their impact on the flow measurement is critical. The artifacts of a representative sample of neurovascular stents were evaluated in vitro with 3D-TOF and 3D-PCMRI sequences. The dependency of the artifacts with respect to the orientation was analyzed for each stent design as well as the impact on the flow measurement accuracy. Furthermore, the 3D-PCMRI data of four patients carrying intracranial aneurysms treated with flow diverter stents were analyzed as illustrative examples. The stent artifacts were mainly confined to the stent lumen therefore indicating the leading role of shielding effect. The influence of the stent design and its orientation with respect to the transmitting MR coils were highlighted. The artifacts impacted the 3D-PCMRI velocities mainly in the low magnitude domains, which were discarded from the analysis ensuring reliable near-stent velocities. The feasibility of in-stent flow measurements was confirmed in vivo on two patients who showed strong correlation between flow and geometric features. In two other patients, the consistency of out-of-stent velocities was verified qualitatively through intra-aneurysmal streamlines except when susceptibility artifacts occurred. The present results motivate the conception of low inductance or nonconductive stent design. Furthermore, the feasibility of near-stent 3D-PCMRI measurements opens the door to clinical applications like the post-treatment follow-up of stenoses or intracranial aneurysms. © 2018 International Society for Magnetic Resonance in Medicine.

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

PubMed Central

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

2015-01-01

A synergistic impact of research in the fields of post-angioplasty restenosis, drug-eluting stents and vascular gene therapy over the past 15 years has shaped the concept of gene-eluting stents. Gene-eluting stents hold promise of overcoming some biological and technical problems inherent to drug-eluting stent technology. As the field of gene-eluting stents matures it becomes evident that all three main design modules of a gene-eluting stent: a therapeutic transgene, a vector and a delivery system are equally important for accomplishing sustained inhibition of neointimal formation in arteries treated with gene delivery stents. This review summarizes prior work on stent-based gene delivery and discusses the main optimization strategies required to move the field of gene-eluting stents to clinical translation. PMID:26225356

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

PubMed

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.

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

PubMed

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

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

PubMed

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.

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

PubMed Central

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

2016-01-01

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. PMID:28787913

Stent selection for both biliary and pancreatic strictures caused by chronic pancreatitis: multiple plastic stents or metallic stents?

PubMed

Gupta, Rajesh; Reddy, D Nageshwar

2011-09-01

Endoscopic stenting is an effective treatment option in the management of both benign biliary strictures and pancreatic ductal strictures. Plastic stents and self-expandable metal stents have been used with variable success for the management of both benign biliary strictures and pancreatic ductal strictures caused by chronic pancreatitis. Fully covered self-expandable metal stents of improved design represent a major technological advance which has added to the endoscopic armamentarium. Both multiple plastic stents and covered self-expandable metal stents have shown promising results. However, data to support the use of self-expandable metal stents over multiple plastic stents or vice versa are still lacking.

Symptomatic stent cast.

PubMed

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

2008-02-01

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

External extension of double-J ureteral stent during pyeloplasty: inexpensive stent and non-cystoscopic removal.

PubMed

Kajbafzadeh, Abdol-Mohammad; Zeinoddini, Atefeh; Ebadi, Maryam; Heidari, Reza; Tajalli, Afshin

2014-04-01

The purpose of the study is to describe our experience with the application of externalized double-J ureteral stent (DJUS) during pyeloplasty for correction of ureteropelvic junction obstruction (UPJO) in order to avoid cystoscopy for stent removal. Pyeloplasty was performed in 523 infants with UPJO using miniature pyeloplasty technique. After removing the obstructed segment, a 3-Fr. DJUS was placed into the ureter. In order to avoid cystoscopy for the removal of the stent, a feeding tube was passed through the skin and renal pelvis via a separate stab incision, connected to the DJUS and secured to the external body surface (skin), and the pyeloplasty was completed. The feeding tube along with the stent was removed after 3-4 weeks, respectively. Postoperative follow-up visits were performed 1, 3, and 6 months after the procedure. The mean operative time was 49 min (range 41-79). Patients were discharged after 17 ± 2 h (mean ± SD). No patient experienced bladder spasm or anticholinergic administration. Forty-four patients (8.4 %) experienced minor complications including non-febrile urinary tract infections and mild hematuria. No major complication including urinoma, leakage, and stent migration or displacement was observed during the follow-up period. Stent removal was tolerated by 99.8 % of patients in an outpatient setting with minimal discomfort without performing cystoscopy. Using external DJUS along with a pyelocutaneous stent extension during pyeloplasty is a safe, feasible, and beneficial technique. This technique resulted in high success rate with minimal cost and no renal injury. The non-cystoscopic stent removal and elimination of urethral catheterization following pyeloplasty are the other advantages of this technique.

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

PubMed

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.

Clinical application of the Natural Y stent in the management of benign carinal stenosis.

PubMed

Nam, Hae-Seong; Um, Sang Won; Koh, Won-Jung; Suh, Gee Young; Chung, Man Pyo; Kwon, O Jung; Kim, Jhingook; Kim, Hojoong

2009-08-01

The Y-shaped structure of the carinal bifurcation causes difficulties in the treatment of carinal stenosis. We describe a new Y-shaped silicone stent, called the Natural Y stent. We investigated its clinical efficacy through a review of patients with benign carinal stenosis who undewent consecutive Natural Y stent placement. Between January 2004 and February 2008, 11 patients underwent ballooning, neodymium:yttrium-aluminum-garnet laser resection, or bougienation (by rigid bronchoscopy) to dilate the airway, followed by placement of the Natural Y stent. The underlying etiologies of carinal stenosis included posttuberculosis stricture in 7 patients (64%), postintubation stenosis in 2 (18%), and postoperative malacia in 2 (18%). All patients reported subjective symptomatic relief immediately after stent placement. No procedurally related deaths or immediate major complications occurred. Stent-related late complications included granulation tissue formation (64%) and mucostasis (18%, defined as > or = 50% narrowing). The median duration of overall stent placement was 439 days (range, 119 to 1729 days). The stents were successfully removed in 4 patients (36%) after a median of 409 days. The Natural Y stent provides an effective and feasible therapeutic modality in patients with benign carinal stenosis, with or without previous thoracic airway interventions.

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

PubMed

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.

Application of memory metallic stents to urinary tract disorders in pediatric patients.

PubMed

Kamata, Shinkichi; Usui, Noriaki; Kamiyama, Masafumi; Yoneda, Akihiro; Tazuke, Yuko; Ooue, Takaharu

2005-03-01

The use of memory metallic stents for the urinary tract in pediatric patients has not been reported. The authors report on 2 patients with urinary tract disorders who were successfully treated with a memory metallic stent. A thermoexpandable, nickel-titanium alloy stent was placed at the urethroureteral junction of a 4-year-old boy with ureteral stenosis associated with cloacal exstrophy for 18 months and at the urethra of a 2-year-old girl with ischuria after a repair of cloacal anomaly for 6 months. Temporary insertion of a memory metallic stent is a safe and effective alternative for organic stricture or functional obstruction of the urinary tract in pediatric patients.

[Application of (125)I seeds combined with biliary stent implantation in the treatment of malignant obstructive jaundice].

PubMed

Wang, T; Liu, S; Zheng, Y B; Song, X P; Jiang, W J; Sun, B L; Wang, L G

2016-03-23

To study the feasibility and therapeutic effect of the application of (125)I seeds combined with biliary stent implantation on the treatment of malignant obstructive jaundice. Fifty patients with malignant obstructive jaundice treated from September 2010 to February 2013 in Yantai Yuhuangding Hospital were included in this study. Among them, 24 patients received biliary stent implantation combined with (125)I seeds intraluminal brachytherapy as experimental group, and 26 were treated by biliary stent implantation as control group.The total bilirubin, direct bilirubin and tumor markers (CA-199, CA-242, CEA) before and after surgery, the biliary stent patency status was assessed, and the survival time was evaluated. The 24 patients in experimental group were implanted with 30 (125)I seeds successfully in a total of 450 seeds. Jaundice was improved greatly in both groups. The CA-199 and CA-242 after treatment in the experimental group were significantly decreased than that before treatment (P=0.003 and P=0.004). CEA was also decreased, but showed no statistical significance (P>0.05). There were no significant improvement comparing the CA-199, CA-242 and CEA before and 2 months after surgery in the control group (P>0.05). The rate of biliary stent patency was 83.3% (20/24) in the experimental group and 57.7% (15/26) in the control group (P=0.048). The mean biliary stent patency time in the experimental group was 9.84 months (range 1-15.5 months). The mean biliary stent patency time in the control group was 5.57 months (range 0.8-9 months). There was a significant difference between the two groups (P=0.018). The median survival time was 10.2 months in the experimental group and 5.4 months in the control group (P<0.05). (125)I seeds combined with biliary stent implantation can inhibit the proliferation of vascular endothelial cells and the growth of tumor effectively, and can prolong the biliary stent patency time and the survival time obviously for patients with

Double stenting with silicone and metallic stents for malignant airway stenosis.

PubMed

Matsumoto, Keitaro; Yamasaki, Naoya; Tsuchiya, Tomoshi; Miyazaki, Takuro; Kamohara, Ryotaro; Hatachi, Go; Nagayasu, Takeshi

2017-08-01

For severe malignant airway stenosis, there are several types of commercially available airway stents, and each has its own advantages and disadvantages. We herein describe the safety and efficacy of combination stenting with silicone and metallic stents for patients with extended malignant airway stenosis. Seven patients with malignant airway stenosis were treated via combination stenting with a silicone stent and a metallic stent for extended airway stenosis from the central to peripheral airways. Five patients were diagnosed with advanced esophageal cancer, two of whom had tracheoesophageal fistulas. One patient had adenoid cystic carcinoma, and another had mediastinal tumor. There were no specific complications related to the double stenting. Combination stenting with silicone and metallic stents proved to be a safe option for patients with severe, extended, and complicated malignant airway stenosis.

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.

PubMed

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 (<30%) 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).

Airway stents

PubMed Central

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

To stent or not to stent: the use of transanastomotic biliary stents in liver transplantation and patient outcomes.

PubMed

Ong, Michelle; Slater, Kellee; Hodgkinson, Peter; Dunn, Nathan; Fawcett, Jonathan

2018-06-01

There is no substantial evidence for the use of biliary stents in bile duct reconstruction during liver transplantation. A longitudinal, retrospective cohort study was performed to compare biliary complications between stented and non-stented patients between 2011 and 2015 at the Princess Alexandra Hospital, Brisbane, Australia. We found no significant difference in biliary complications between stented and non-stented groups. Stented patients were 3.31 times as likely to require subsequent intervention, mainly in the form of stent removal. These results suggest that there is limited benefit in the placement of endobiliary stents in liver transplantation. Given that this was purely an observational study, causality cannot be proven and a prospective cohort trial would be beneficial in further defining these relationships. © 2018 Royal Australasian College of Surgeons.

Behaviour of two typical stents towards a new stent evolution.

PubMed

Simão, M; Ferreira, J M; Mora-Rodriguez, J; Fragata, J; Ramos, H M

2017-06-01

This study explores the analysis of a new stent geometry from two typical stents used to treat the coronary artery disease. Two different finite element methods are applied with different boundary conditions to investigate the stenosis region. Computational fluid dynamics (CFD) models including fluid-structure interaction are used to assess the haemodynamic impact of two types of coronary stents implantation: (1) type 1-based on a strut-link stent geometry and (2) type 2-a continuous helical stent. Using data from a recent clinical stenosis, flow disturbances and consequent shear stress alterations introduced by the stent treatment are investigated. A relationship between stenosis and the induced flow fields for the two types of stent designs is analysed as well as the correlation between haemodynamics and vessel wall biomechanical factors during the initiation and development of stenosis formation in the coronary artery. Both stents exhibit a good performance in reducing the obstruction artery. However, stent type 1 presents higher radial deformation than the type 2. This deformation can be seen as a limitation with a long-term clinical impact.

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

PubMed

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 < 0.01). The radial force of the thoracic stents was greater than that of all three endovascular stents (P < 0.01). Differences in radial force depend on types of 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.

Process of prototyping coronary stents from biodegradable Fe-Mn alloys.

PubMed

Hermawan, Hendra; Mantovani, Diego

2013-11-01

Biodegradable stents are considered to be a recent innovation, and their feasibility and applicability have been proven in recent years. Research in this area has focused on materials development and biological studies, rather than on how to transform the developed biodegradable materials into the stent itself. Currently available stent technology, the laser cutting-based process, might be adapted to fabricate biodegradable stents. In this work, the fabrication, characterization and testing of biodegradable Fe-Mn stents are described. A standard process for fabricating and testing stainless steel 316L stents was referred to. The influence of process parameters on the physical, metallurgical and mechanical properties of the stents, and the quality of the produced stents, were investigated. It was found that some steps of the standard process such as laser cutting can be directly applied, but changes to parameters are needed for annealing, and alternatives are needed to replace electropolishing. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Bare metal stents, durable polymer drug eluting stents, and biodegradable polymer drug eluting stents for coronary artery disease: mixed treatment comparison meta-analysis

PubMed Central

Toklu, Bora; Amoroso, Nicholas; Fusaro, Mario; Kumar, Sunil; Hannan, Edward L; Faxon, David P; Feit, Frederick

2013-01-01

Objective To compare the efficacy and safety of biodegradable polymer drug eluting stents with those of bare metal stents and durable polymer drug eluting stents. Design Mixed treatment comparison meta-analysis of 258 544 patient years of follow-up from randomized trials. Data sources and study selection PubMed, Embase, and Central were searched for randomized trials comparing any of the Food and Drug Administration approved durable polymer drug eluting stents (sirolimus eluting, paclitaxel eluting, cobalt chromium everolimus eluting, platinum chromium everolimus eluting, zotarolimus eluting-Endeavor, and zotarolimus eluting-Resolute) or biodegradable polymer drug eluting stents, with each other or against bare metal stents. Outcomes Long term efficacy (target vessel revascularization, target lesion revascularization) and safety (death, myocardial infarction, stent thrombosis). Landmark analysis at more than one year was evaluated to assess the potential late benefit of biodegradable polymer drug eluting stents. Results From 126 randomized trials and 258 544 patient years of follow-up, for long term efficacy (target vessel revascularization), biodegradable polymer drug eluting stents were superior to paclitaxel eluting stents (rate ratio 0.66, 95% credibility interval 0.57 to 0.78) and zotarolimus eluting stent-Endeavor (0.69, 0.56 to 0.84) but not to newer generation durable polymer drug eluting stents (for example: 1.03, 0.89 to 1.21 versus cobalt chromium everolimus eluting stents). Similarly, biodegradable polymer drug eluting stents were superior to paclitaxel eluting stents (rate ratio 0.61, 0.37 to 0.89) but inferior to cobalt chromium everolimus eluting stents (2.04, 1.27 to 3.35) for long term safety (definite stent thrombosis). In the landmark analysis after one year, biodegradable polymer drug eluting stents were superior to sirolimus eluting stents for definite stent thrombosis (rate ratio 0.29, 0.10 to 0.82) but were associated with increased

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

PubMed

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.

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

PubMed Central

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

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

PubMed

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.

Therapeutic efficacy and stent patency of transhepatic portal vein stenting after surgery

PubMed Central

Jeon, Ung Bae; Kim, Chang Won; Kim, Tae Un; Choo, Ki Seok; Jang, Joo Yeon; Nam, Kyung Jin; Chu, Chong Woo; Ryu, Je Ho

2016-01-01

AIM To evaluate portal vein (PV) stenosis and stent patency after hepatobiliary and pancreatic surgery, using abdominal computed tomography (CT). METHODS Percutaneous portal venous stenting was attempted in 22 patients with significant PV stenosis (> 50%) - after hepatobiliary or pancreatic surgery - diagnosed by abdominal CT. Stents were placed in various stenotic lesions after percutaneous transhepatic portography. Pressure gradient across the stenotic segment was measured in 14 patients. Stents were placed when the pressure gradient across the stenotic segment was > 5 mmHg or PV stenosis was > 50%, as observed on transhepatic portography. Patients underwent follow-up abdominal CT and technical and clinical success, complications, and stent patency were evaluated. RESULTS Stent placement was successful in 21 patients (technical success rate: 95.5%). Stents were positioned through the main PV and superior mesenteric vein (n = 13), main PV (n = 2), right and main PV (n = 1), left and main PV (n = 4), or main PV and splenic vein (n = 1). Patients showed no complications after stent placement. The time between procedure and final follow-up CT was 41-761 d (mean: 374.5 d). Twenty stents remained patent during the entire follow-up. Stent obstruction - caused by invasion of the PV stent by a recurrent tumor - was observed in 1 patient in a follow-up CT performed after 155 d after the procedure. The cumulative stent patency rate was 95.7%. Small in-stent low-density areas were found in 11 (55%) patients; however, during successive follow-up CT, the extent of these areas had decreased. CONCLUSION Percutaneous transhepatic stent placement can be safe and effective in cases of PV stenosis after hepatobiliary and pancreatic surgery. Stents show excellent patency in follow-up abdominal CT, despite development of small in-stent low-density areas. PMID:27956806

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

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Stent-induced coronary artery stenosis characterized by multimodal nonlinear optical microscopy

NASA Astrophysics Data System (ADS)

Wang, Han-Wei; Simianu, Vlad; Locker, Mattew J.; Cheng, Ji-Xin; Sturek, Michael

2011-02-01

We demonstrate for the first time the applicability of multimodal nonlinear optical (NLO) microscopy to the interrogation of stented coronary arteries under different diet and stent deployment conditions. Bare metal stents and Taxus drug-eluting stents (DES) were placed in coronary arteries of Ossabaw pigs of control and atherogenic diet groups. Multimodal NLO imaging was performed to inspect changes in arterial structures and compositions after stenting. Sum frequency generation, one of the multimodalities, was used for the quantitative analysis of collagen content in the peristent and in-stent artery segments of both pig groups. Atherogenic diet increased lipid and collagen in peristent segments. In-stent segments showed decreased collagen expression in neointima compared to media. Deployment of DES in atheromatous arteries inhibited collagen expression in the arterial media.

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.

PubMed

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 < 0.001). G2-DES were associated with a similar risk of 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 < 0.001), but not with G2-DES compared with BMS (OR: 1.01; 95% CI: 0.32 to 3.25; p = 0.98). In a large cohort of unselected patients undergoing coronary 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.

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

PubMed

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.

A systematic review of biodegradable biliary stents: promising biocompatibility without stent removal.

PubMed

Siiki, Antti; Sand, Juhani; Laukkarinen, Johanna

2018-05-18

Biodegradable self-expanding stents are an emerging alternative to standard biliary stents as the development of endoscopic insertion devices advances. The aim was to systematically review the existing literature on biodegradable biliary stents. In-vivo studies on the use of biodegradable stents in the biliary duct were systematically reviewed from 1990 to 2017. Despite extensive research on the biocompatibility of stents, the experience so far on their clinical use is limited. A few favorable reports have recently been presented on endoscopically and percutaneously inserted self-expanding biodegradable polydioxanone stents in benign biliary strictures. Another potential indication appears to be postcholecystectomy leak of the cystic duct. The main benefit of biodegradable stents is that stent removal can be avoided. The biocompatibility of the current biodegradable stent materials, most prominently polydioxanone, is well documented. In the few studies currently available, biodegradable stents are reported to be feasible and safe, also in humans. The initial results of the endoscopic use of these stents in benign biliary stricture management and for treating postcholecystectomy bile leaks are promising. Further controlled studies on long-term clinical results and cost-effectiveness are needed.

Low symptomatic premature stent occlusion of multiple plastic stents for benign biliary strictures: comparing standard and prolonged stent change intervals.

PubMed

Lawrence, Christopher; Romagnuolo, Joseph; Payne, K Mark; Hawes, Robert H; Cotton, Peter B

2010-09-01

Benign biliary strictures are typically managed endoscopically whereby an increasing size or number of plastic stents is placed at ERCP. Stents are often changed every 3 to 4 months based on the known median patency of a single biliary stent, but patency data for multiple biliary stents are lacking. To assess the incidence of occlusion-free survival of multiple plastic biliary stents and the rate of premature occlusion if left in longer than 6 months. Retrospective. Tertiary-care medical center (Charleston, SC). Consecutive patients who received multiple plastic stents for benign nonhilar biliary strictures from 1994 to 2008 were identified. Exchange of multiple plastic biliary stents within 6 months (group 1) or 6 months or longer (group 2) after placement. Symptomatic stent occlusion. Seventy-nine patients with nonhilar extrahepatic benign biliary stricture underwent 125 ERCPs with multiple plastic biliary stents. Stents were scheduled for removal/exchange within 6 months in 52 patients (86 ERCPs) compared with after 6 months in 22 patients (26 ERCPs). The median interval between multiple stent placement and removal/exchange was 90 days for group 1 and 242 days for group 2. Premature stent occlusion occurred in 4 of 52 (7.7%) patients in group 1 versus 1 of 22 (4.5%) in group 2, with significantly longer occlusion-free survival in group 2 (log-rank P < .0001). Retrospective study at a single tertiary referral center. Multiple plastic biliary stents for benign nonhilar strictures were associated with a low rate of premature symptomatic stent occlusion at more than 6 months and a longer occlusion-free survival. Copyright 2010 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

Novel application of an established technique for removing a knotted ureteric stent.

PubMed

Tempest, Heidi; Turney, Ben; Kumar, Sunil

2011-04-13

This report describes a case whereby a ureteric stent became knotted during removal and lodged within the upper ureter. The authors describe a novel minimally invasive technique to remove the knotted ureteric stent using the holmium laser.

Delivery of large biopharmaceuticals from cardiovascular stents: a review

PubMed Central

Takahashi, Hironobu; Letourneur, Didier; Grainger, David W.

2008-01-01

This review focuses on the new and emerging large-molecule bioactive agents delivered from stent surfaces in drug-eluting stents (DES) to inhibit vascular restenosis in the context of interventional cardiology. New therapeutic agents representing proteins, nucleic acids (small interfering RNAs and large DNA plasmids), viral delivery vectors and even engineered cell therapies require specific delivery designs distinct from traditional smaller molecule approaches on DES. While small molecules are currently the clinical standard for coronary stenting, extension of the DES to other lesion types, peripheral vasculature and non-vasculature therapies will seek to deliver an increasingly sophisticated armada of drug types. This review describes many of the larger molecule and biopharmaceutical approaches reported recently for stent-based delivery with the challenges associated with formulating and delivering these drug classes compared to the current small molecule drugs. It also includes perspectives on possible future applications that may improve safety and efficacy and facilitate diversification of the DES to other clinical applications. PMID:17929968

Clinical Application of Fully Covered Self-Expandable Metal Stents in the Treatment of Bronchial Fistula.

PubMed

Cao, Ming; Zhu, Qiang; Wang, Wei; Zhang, Tian Xiao; Jiang, Min Zhong; Zang, Qi

2016-09-01

Background The study was designed to access the feasibility, safety, and efficacy of fully covered self-expandable metal stents in the treatment of bronchial fistula. Methods Clinical data of nine patients (seven males and two females) who were treated with placement of tracheobronchial or bronchial fully covered self-expandable metal stents from August 2005 to November 2011 were analyzed retrospectively. Among these patients, seven were diagnosed with bronchopleural fistula, one with tracheopleural fistula, and one with left main bronchoesophageal fistula. Eight had accompanying thoracic empyema. The fistula orifices ranged from 3.5 mm to 25 mm in diameter. All patients received topical anesthesia. L-shaped stents were placed in six patients and I-shaped stents in three under fluoroscopic guidance. After stent placement, patients with empyema were treated with pleural lavage. Results Stent placement in the tracheobronchial tree was successful in all patients, without procedure-related complications. The operating time was 5 to 16 minutes. A small amount of bubble overflowed from the intrathoracic drainage tube of only one patient. In the other patients, the bubble in the intrathoracic drainage tube disappeared immediately or angiography showed no overflow of contrast agent from the fistula orifice. The effective rate of fistula orifice closure after stent placement was 100%, with 88.9% rated as excellent. One patient coughed the stent out 5 days after placement and hence a new stent was placed. Among the patients with empyema, one died of septicemia arising from empyema on day 8 and another died of brain metastases of lung cancer 6 months after stent insertion with persistent empyema. In the other six patients, empyema resolved after 2 to 5 months (cure rate 75%). Seven patients were followed up for 3 to 36 months. During follow-up, one stent was removed 8 months after implantation due to difficult expectoration, without recurrent empyema. The remaining

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

NASA Astrophysics Data System (ADS)

Jiang, Yongfei; Zhang, Jun; Zhao, Wanhua

2016-05-01

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

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

PubMed

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

2014-06-01

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

Expandable metal stents for endoscopic bilateral stent-within-stent placement for malignant hilar biliary obstruction.

PubMed

Chahal, Prabhleen; Baron, Todd H

2010-01-01

Placement of biliary stents is effective for palliation of unresectable hilar malignant biliary obstruction. However, when bilateral self-expandable metal stents (SEMSs) are used, placement can be technically challenging. In many studies, side-by-side placement is performed, although it is unclear whether this is the most anatomical and functional approach. We sought to assess the technical feasibility and effectiveness of deploying bilateral SEMSs with a stent-within-stent approach using commercially available stents with a large cell width. Retrospective study. Tertiary care medical center. Patients with malignant biliary hilar obstruction referred for endoscopic palliation of obstructive jaundice. Technical success, ie, successful bilateral SEMS placement across the stricture; functional success, ie, decrease in pretreatment bilirubin level; early and late complications; and stent patency. Bilateral biliary drainage was attempted and successfully established in 21 patients with malignant hilar obstruction (15 men, 6 women; mean age 63.7 [standard deviation 13.9] years), resulting in clinical improvement of obstructive symptoms. Median follow-up was 6.14 months (interquartile range 3.5-9.5 months). There were 1 (5%) early and 7 (33%) late stent occlusions that required endoscopic reintervention. The 30-day mortality rate was 10% (2 deaths). Retrospective study of a series of cases treated at a tertiary care center by expert endoscopists. This simple technique was performed by using an open-cell expandable metal stent is technically feasible and easy and allows bilateral placement of SEMSs in patients with unresectable hilar malignancy. 2010 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

Novel application of an established technique for removing a knotted ureteric stent

PubMed Central

Tempest, Heidi; Turney, Ben; Kumar, Sunil

2011-01-01

This report describes a case whereby a ureteric stent became knotted during removal and lodged within the upper ureter. The authors describe a novel minimally invasive technique to remove the knotted ureteric stent using the holmium laser. PMID:22701009

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

PubMed

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 < .0001). After 4 months, anastomosis was functionally patent in all cases. However, elastic fibers remained interrupted in all 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.

Application of self-expandable metal stents for ureteroileal anastomotic strictures: long-term results.

PubMed

Liatsikos, Evangelos N; Kagadis, George C; Karnabatidis, Dimitrios; Katsanos, Konstantinos; Papathanassiou, Zafiria; Constantinides, Constantinos; Perimenis, Petros; Nikiforidis, George C; Stolzenburg, Jens-Uwe; Siablis, Dimitrios

2007-07-01

We report our long-term experience with the management of benign ureteroileal anastomotic strictures using self-expandable metal stents. A total of 16 male and 2 female patients with a mean+/-SD age of 72+/-7 years (range 66 to 78) with benign fibrotic strictures at the site of ureteroileal anastomosis underwent implantation of self-expandable metal stents with a nominal diameter of 6 to 8 mm. A total of 24 ureteroileal conduits were treated. The external nephrostomy tubes were removed after fluoroscopic validation of ureteral patency. Patients were followed with blood biochemistry, ultrasonography, urography and/or virtual endoscopy. Retrograde external-internal catheter insertion through the cutaneous stoma was performed in cases of recalcitrant stricture. The technical success rate of ureteroileal stricture crossing and stenting was 100% (24 of 24 cases). Mean followup was 21 months (range 7 to 50). The clinical success rate during the immediate post-stenting period was 70.8% (17 of 24 cases). The 1 and 4-year primary patency rates were 37.8% and 22.7%, respectively. Secondary interventions included repeat balloon dilation in 15 ureters, of which 8 also underwent subsequent coaxial stent placement. The 1 and 4-year secondary patency rates were 64.8% and 56.7%, respectively. Except in 2 patients who died external-internal Double-J catheters continued to be inserted retrograde in 6 ureteroileal conduits. They are periodically exchanged to prevent mucous inspissation and stent encrustation. Metal stents served as the definitive treatment for stricture in more than half of the cases, whereas in the remainder the stents allowed the uncomplicated and regular exchange of Double-J catheters in retrograde fashion. This combined, less invasive treatment for ureteroileal anastomotic strictures may help patients avoid surgical revision and preserve quality of life.

Treatment of central venous in-stent restenosis with repeat stent deployment in hemodialysis patients.

PubMed

Ronald, James; Davis, Bradley; Guevara, Carlos J; Pabon-Ramos, Waleska M; Smith, Tony P; Kim, Charles Y

2017-05-15

To report patency rates for stent deployment for treatment of in-stent stenosis of the central veins of the chest in hemodialysis patients. A retrospective analysis was performed on 29 patients who underwent 35 secondary percutaneous transluminal stent (PTS) deployments for in-stent stenosis within the central veins that were refractory to angioplasty and ipsilateral to a functioning hemodialysis access (in-stent PTS group). For comparison, patency data were acquired for 47 patients who underwent 78 successful percutaneous transluminal angioplasty (PTA) procedures for in-stent stenosis (in-stent PTA group) and 55 patients who underwent 55 stent deployments within native central vein stenosis refractory to angioplasty (native vein PTS group). The 3-, 6-, and 12-month primary lesion patency for the in-stent PTS group was 73%, 57%, and 32%, respectively. The 3-, 6-, and 12-month primary patency for the in-stent PTA group was 70%, 38%, and 17% and for the native vein PTS group was 78%, 57%, and 26%, which were similar to the in-stent PTS group (p = 0.20 and 0.41, respectively). The 3-, 6-, and 12-month secondary access patency was 91%, 73%, and 65% for the in-stent PTS group. Sub-analysis of the in-stent PTS group revealed no difference in primary (p = 0.93) or secondary patency rates (p = 0.27) of bare metal stents (n = 23) compared with stent grafts (n = 12). Stent deployment for central vein in-stent stenosis refractory to angioplasty was associated with reasonable patency rates, which were similar to in-stent PTA and native vein PTS.

Fatigue and In Vivo Validation of a Peritoneum-Lined Self-Expanding Nitinol Stent-Graft

PubMed Central

Bastijanic, Jennifer M.; Etscheidt, Jordan; Sattiraju, Mallika; Bonsignore, Craig; Kopchok, George; White, Rodney; Sarac, Timur P.

2014-01-01

Purpose To assess the fatigue and in vivo performance of a new stent-graft incorporating bovine peritoneum lining that is designed for application in peripheral vascular occlusive disease. Methods Bovine peritoneum-lined stent-grafts were subjected to accelerated in vitro pulsatile fatigue and axial/torsional fatigue testing designed to simulate 10 years of physiological strain on the devices. At specified times the devices were evaluated for stent fracture, suture failure, or tissue tearing. Seven dogs underwent bilateral common iliac artery (CIA) balloon angioplasty injury with unilateral placement of the peritoneum-lined stent-graft. Angiography and intravascular ultrasound were performed prior to treatment, after treatment, and prior to sacrifice at 30 days. Vessels were perfusion fixed and histologically evaluated at 5 regions: above stent, proximal stent, mid stent, distal stent, and below stent. Results No evidence of stent, suture, or tissue failure was present during or after pulsatile and axial/torsional fatigue testing. At 30±0.3 days after implantation, all vessels were patent. The average lumen area at explantation across stented vessels was 25.45 mm2. Lumen areas tended to be reduced above (23.57 mm2) and below (24.17 mm2) the stent. Lumen areas were consistent across stented regions at explantation (proximal stent 27.80 mm2, mid stent 25.88 mm2, and distal stent 25.81 mm2). The mean neointimal area in peritoneum-lined stents was 2.02±1.52 mm2, with a neointima:media ratio of 1.03±0.50. These values were significantly lower in the above and below stent areas than in the stented regions, but there was no difference in either measure within the proximal, mid, or distal stent. Conclusion The custom-designed peritoneum-lined stent-graft is promising for clinical peripheral applications due to its ability to resist relevant long-term physiological stresses and outstanding short-term patency rates in canine implantations. PMID:25290804

iStent trabecular micro-bypass stent for open-angle glaucoma

PubMed Central

Le, Kim; Saheb, Hady

2014-01-01

Trabecular micro-bypass stents, commonly known as iStents, are micro-invasive glaucoma surgery (MIGS) devices used to treat open-angle glaucoma. Like other MIGS procedures that enhance trabecular outflow, the iStent lowers intraocular pressure (IOP) by creating a direct channel between the anterior chamber and Schlemm’s canal. iStents are typically implanted at the time of phacoemulsification for patients with open-angle glaucoma and visually significant cataracts. This review summarizes the published data regarding the efficacy, safety, and cost considerations of trabecular micro-bypass stents. Most studies found statistically significant reductions in mean IOP and ocular medication use after combined phacoemulsification with single or double iStent implantation. The devices were found to be very safe, with a safety profile similar to that of cataract surgery. Complications were infrequent, with the most common complications being temporary stent obstruction or malposition, which resolved with observation or secondary procedures. Future studies are needed to evaluate long-term outcomes, patient satisfaction, cost effectiveness, and expanded indications. PMID:25284980

Development of Biliary and Enteral Stents by the Korean Gastrointestinal Endoscopists

PubMed Central

Shim, Chan Sup; Kim, Jin Hong; Bok, Gene Hyun

2016-01-01

Stenting in the gastrointestinal tract is a common procedure used for palliation of obstruction in the enteral and biliary tract. Today, stenting of malignant and benign strictures is performed at almost every major tertiary hospital in Korea. Moreover, Korea has become a major global supplier of cutting edge technology in the field of self-expanding metal stents. However, the history of stenting in Korea is relatively short and was far behind that of other nations such as Japan and Germany. The authors are humbled and gratified to have been able to observe the development and application of these stents in Korea, first hand. In this article, the authors review the overall history of stenting with a specific focus on the development of stenting in Korea. The development of esophageal, gastroduodenal, biliary, and colonic stents in Korea are reviewed in this article from a chronological and historical point of view, and a personal account of some of the significant moments of stent development in Korea are described. PMID:26956192

[Clinical application of a fully covered self-expandable metallic stent in treatment of airway fistula].

PubMed

Zhu, Qiang; Zang, Qi; Jiang, Zhong-min; Wang, Wei; Cao, Ming

2013-06-01

To assess the feasibility, safety and efficacy of the use of a fully covered self-expandable stent for the treatment of airway fistula. From August 2005 to November 2011, 9 patients underwent treatment by the introduction of a tracheo-bronchial or bronchial fully covered self-expandable metallic stent. There were 7 males and 2 females, aged from 28-65 years with a mean of 46 years. In this group, 7 cases were diagnosed as bronchopleural fistula, 1 case as tracheopleural fistula, 1 case as broncho-esophageal fistula, 8 cases with thoracic empyema. The fistula orifices were from 3.5-25.0 mm in diameter with a mean 8.4 mm. All patients received topical anesthesia, and L-shaped stent was placed in 6 patients and I-shaped stent in 3 patients under fluoroscopic guidance. After the stent placement, the patients with empyema were treated with continual irrigation of the empyema cavity. Stent placement in the tracheo-bronchial tree was technically successful in all patients, without procedure-related complications. The operating time was from 5-16 minutes, mean time (10 ± 4) minutes. Except for 1 patient, immediate closure of the airway fistula was achieved in the other patients after the procedure, as shown by the immediate cessation of bubbling in the chest drain system or the contrast examination. In this study, 1 patient coughed the inserted stent out due to irritable cough on the 5th day and had to receive repositioning of a new stent. Among the patients who were with empyema, 1 patient died of septicemia on the 8th day and 1 patient died of brain metastases from lung cancer 6 months after the stent insertion with empyema not cured, the other 6 patients' empyema healed from 2-5 months, mean time 3.7 months. Seven patients were followed from 3 to 36 months with a median of 13.5 months. During follow-up, 1 stent was removed from a patient 8 months after the stent implantation without empyema recurred. The remaining patient presented good tolerability to the existence of

Cross-cultural application of the Korean version of Ureteral Stent Symptoms Questionnaire.

PubMed

Park, Jinsung; Shin, Dong Wook; You, Changhee; Chung, Kyung Jin; Han, Deok Hyun; Joshi, Hrishi B; Park, Hyung Keun

2012-11-01

We validated the Korean version of the Ureteral Stent Symptoms Questionnaire (USSQ) in patients with an indwelling ureteral stent. Linguistic validation of the original USSQ was performed through a standard process including translation, back translation, and pilot study. A total of 65 patients who underwent ureteroscopic surgery were asked to complete the Korean USSQ as well as EuroQOL (male and female), the International Prostate Symptom Score (male), and Urogenital Distress Inventory-6 (female). Patients were evaluated at weeks 1 and 2 after stent placement and at week 4 after removal. Sixty-four healthy subjects without a ureteral stent were also asked to complete the Korean USSQ once. The psychometric properties of the questionnaire were analyzed. Internal consistencies (Cronbach α coefficients: 0.73-0.83) and test-retest reliability (Spearman correlation coefficient: ≥0.6) were satisfactory for urinary symptom, body pain, general health, and work performance domains. Most USSQ domains showed moderate correlations with each other. Convergent validity determined by correlation between other instruments and corresponding USSQ domain was satisfactory. Sensitivity to change and discriminant validity were also good in most domains (P<0.01). Only a small proportion of the study population had an active sexual life, with the stent in situ, limiting its analysis. The Korean version of the USSQ is a reliable and valid instrument that can be self-administered by Korean patients with a ureteral stent in the clinical and research settings. Further clinical studies in the Korean settings would be useful to provide robust data on sensitivity to change.

Forgotten CBD stent (102 months) with stone-stent complex: A case report.

PubMed

Barai, Varsha; Hedawoo, Jagadish; Changole, Sanjay

2017-01-01

Choledocholithiasis is presence of stone in Common bile duct (CBD) which can be treated by endoscopy or surgery [1]. Retained foreign bodies like stents forms a nidus for stone formation resulting in pain, fever, jaundice. 60 years female patient admitted in surgery ward with features of cholangitis with computed tomography showing cholangitic abscess with dilated common bile duct and sludge around stent in situ. Stone was found at proximal end of stent during surgery. Stents may remain without complications or may migrate, and rarely form nidus for stone formation. If kept for long time they lead to bacterial proliferation, biofilm formation and precipitation of calcium bilirubinate presenting as fever, pain, jaundice. Stent-stone complex can be treated endoscopically and surgically [6,7]. As stent can cause stone formation, infection and other complications, timely removal of stent should advised. III-effects of stent in-situ should be explained, record should be maintained [8] and patient should be advised regular follow up and stent removal after 6 weeks. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Management of endoscopic biliary stenting for choledocholithiasis: Evaluation of stent-exchange intervals.

PubMed

Tohda, Gen; Dochin, Masaki

2018-01-16

To evaluate the best management of plastic stents in patients with choledocholithiasis who were unfit for endoscopic stone removal or surgery. Between April 2007 and September 2017, 87 patients (median age 83.7 years) with symptomatic choledocholithiasis were treated with insertion of 7-Fr plastic stents because complete endoscopic stone retrieval was difficult, and their general condition was not suitable for surgery. Seventy of these patients agreed to regular stent management and stent exchange was carried out at every 6 mo (Group A, n = 35) or every 12 mo (Group B, n = 35). The remaining 17 patients did not accept regular stent exchange, and stents were replaced when clinical symptoms appeared (Group C). We evaluated the frequency of biliary complication and stent patency rate during follow-up periods. The patency rate of biliary plastic stents was 91.4% at 6 mo (Group A) and 88.6% at 12 mo (Group B), respectively. Acute cholangitis occurred in 2.9% of Group A patients and in 8.6% of Group B patients. In Group C, median stent patency was 16.3 mo, and stent exchange was carried out in 70.6% of cases because of acute cholangitis or obstructive jaundice. Although a high incidence of acute cholangitis occurred, there was no biliary-related mortality. Plastic stent exchange at 12-mo intervals is considered a safe procedure for patients with choledocholithiasis. Long-term biliary stenting increases biliary complications, but it can be an acceptable option for select patients who are medically unfit for further invasive procedures.

[Stents in urology].

PubMed

Mattei, A; Danuser, H

2003-04-01

Ureteral stents are employed in the upper and urethral stents in the lower urinary tract for restitution or maintenance of urinary drainage. Placement of ureteral stents is indicated as an adjuvant measure prior to extracorporal disintegration (ESWL) of large kidney stones to insure urinary drainage and enhance expulsion of fragments and disintegrate. Also, obstruction by very small urinary tract stones that are not treatable by ESWL because they cannot be localized can be relieved by placement of a double-J-stent with immediate elimination of colic. If the cause of urinary tract obstruction is external ureteral compression (retroperitoneal mass), placement of a special tumor stent is one possibility. This, however, has the danger of becoming reobstructed with detritus and blockage of the drainage holes in the stent. In these cases the essential drainage along the stent is blocked by the mass. Therefore, a percutaneous nephrostomy providing direct drainage is easier to control and preferable. Obstructive pyelonephritis is an absolute indication for drainage of the upper urinary tract with a double-J-stent, or even better by percutaneous nephrostomy. If pyeloureteral or ureteral stenoses of the upper urinary tract are opened endoscopically, then the double-J-stent serves to maintain and insure drainage until the new lumen is reepithelialized. In patients with prostatic hyperplasia who no longer respond to medical treatment and who are not candidates for more invasive surgical treatment, a stent can be placed in the prostatic urethra under local anesthesia as a last resort. This procedure is seldom used but, in view of the satisfactory long-term results, it provides a true alternative to bladder drainage by transurethral catheter or percutaneous cystostomy. The same stents may be used in the bulbar urethra to reduce restricture rates following endoscopic treatment of strictures.

Establishing an endovascular carotid stent program.

PubMed

Raabe, Rod; Chong, Brian

2004-12-01

FDA approval of carotid stent and distal protection devices has transformed carotid artery stenting (CAS) from an investigational procedure to a practical application. Recent approval by the Center for Medicare Services (CMS) has ensured that CAS will be a part of everyday practice throughout the country. To establish a competitive endovascular carotid stent program, one needs to develop an effective strategy. The key to success is substance and service. A high-quality clinical program with excellent communication between the patient and referring physician is essential. You must first get access to the patient by establishing a clinical practice. As a radiologist, you have the advantage of gaining access by identifying appropriate patients through noninvasive vascular labs, CTA, and MRA. An algorithm-driven evaluation and treatment protocol with good pre- and postoperative care, along with a quality assurance program, will ensure that your carotid stent program has substance and delivers optimal service. With good planning, you will have a firm clinical foundation for treatment of carotid artery stenosis in your community. Putting all of the ingredients together will ensure a successful carotid endovascular program.

Impact of loop-tail ureteral stents on ureteral stent-related symptoms immediately after ureteroscopic lithotripsy: Comparison with pigtail ureteral stents

PubMed Central

Inoue, Takaaki; Muguruma, Kouei; Murota, Takashi; Kinoshita, Hidefumi; Matsuda, Tadashi

2017-01-01

Purpose To evaluate urination-related quality of life (QoL) in patients with an indwelling ureteral stent immediately after ureteroscopic lithotripsy (URSL) for upper urinary calculi. We compared the effects of loop-tail and pigtail ureteral stents on urination-related QoL. Materials and Methods Of 135 patients who underwent URSL between May 2014 and March 2015 at our hospital, we retrospectively analyzed the records of 70 patients (42 men, 28 women; median age, 63 years) in whom the stent tail was positioned inside the bladder without crossing the midline and who completed the core lower urinary tract symptoms score (CLSS) questionnaire pre- and postoperatively. Results There were significant differences in incomplete emptying (p=0.048) and bladder pain (p=0.041) between patients with loop-tail versus pigtail ureteral stents after URSL. In the multivariate analysis, stent type had a stronger association with incomplete emptying (p=0.022) and bladder pain (p=0.018) than age, sex, body mass index, stent side, operation time, diameter of ureteral access sheath, and stent type. Conclusions Patients with loop-tail ureteral stents had better urination-related QoL in the immediate post-URSL stage than patients with pigtail stents. PMID:29124244

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

PubMed

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.

Very late stent thrombosis in a bare-metal stent, 9 years after implantation.

PubMed

Almasswary, Adel A

2009-06-01

Very late bare-metal stent thrombosis occurring beyond one year after stenting is uncommon. We report a case of bare-metal stent thrombosis presenting as acute myocardial infarction. The patient's stent was implanted 9 years ago, however, he was not adherent to his antiplatelet therapy (aspirin). This case highlights the importance of antiplatelet therapy in patients with stents even many years after implantation.

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

PubMed

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

2015-11-01

The most common causes of in-stent restenosis (ISR) are intimal hyperplasia and stent under expansion. The purpose of this study was to use intravascular ultrasound (IVUS) to compare the ISR mechanisms of bare metal stents (BMS), first-generation drug-eluting stents (DES), and second-generation DES. There were 298 ISR lesions including 52 BMS, 73 sirolimus-eluting stents, 52 paclitaxel-eluting stents, 16 zotarolimus-eluting stents, and 105 everolimus-eluting stent. Mean patient age was 66.6 ± 1.1 years, 74.2% were men, and 48.3% had diabetes mellitus. BMS restenosis presented later (70.0 ± 66.7 months) with more intimal hyperplasia compared with DES (BMS 58.6 ± 15.5%, first-generation DES 52.6 ± 20.9%, second-generation DES 48.2 ± 22.2%, p = 0.02). Although reference lumen areas were similar in BMS and first- and second-generation DES, restenotic DES were longer (BMS 21.8 ± 13.5 mm, first-generation DES 29.4 ± 16.1 mm, second-generation DES 32.1 ± 18.7 mm, p = 0.003), and stent areas were smaller (BMS 7.2 ± 2.4 mm(2), first-generation DES 6.1 ± 2.1 mm(2), second-generation DES 5.7 ± 2.0 mm(2), p <0.001). Stent fracture was seen only in DES (first-generation DES 7 [5.0%], second-generation DES 8 [7.4%], p = 0.13). In conclusion, restenotic first- and second-generation DES were characterized by less neointimal hyperplasia, smaller stent areas, longer stent lengths, and more stent fractures than restenotic BMS. Copyright © 2015 Elsevier Inc. All rights reserved.

A new polymer-free drug-eluting stent with nanocarriers eluting sirolimus from stent-plus-balloon compared with bare-metal stent and with biolimus A9 eluting stent in porcine coronary arteries.

PubMed

Takimura, Celso K; Galon, Micheli Z; Gutierrez, Paulo S; Sojitra, Prakash; Vyas, Ashwin; Doshi, Manish; Lemos, Pedro A

2015-04-01

Permanent polymers in first generation drug-eluting stent (DES) have been imputed to be a possible cause of persistent inflammation, remodeling, malapposition and late stent thrombosis. We aim to describe the in vivo experimental result of a new polymer-free DES eluting sirolimus from stent-plus-balloon (Focus np stent, Envision Scientific) compared with a bare-metal stent (BMS) (Amazonia CroCo, Minvasys) and with a biolimus A9 eluting stent (Biomatrix, Biosensors). In 10 juvenile pigs, 23 coronary stents were implanted in the coronary arteries (8 Amazonia CroCo, 8 Focus np, and 7 Biomatrix). At 28-day follow-up, optical coherence tomography (OCT) and histology were used to evaluate neointimal hyperplasia and healing response. According to OCT analysis, Focus np stents had a greater lumen area and less neointimal hyperplasia response than BMS and Biomatrix had. Histomorphometry results showed less neointimal hyperplasia in Focus np than in BMS. Histology showed a higher fibrin deposition in Biomatrix stent compared to Focus np and BMS. The new polymer-free DES with sirolimus eluted from stent-plus-balloon demonstrated safety and reduced neointimal proliferation compared with the BMS and Biomatrix stents at 28-day follow-up in this porcine coronary model. This new polymer-free DES is promising and warrants further clinical studies.

[Feasibility and possibility of Inoue stent graft for thoracic aortic aneurysms].

PubMed

Marui, Akira; Kimura, Takeshi; Tazaki, Junichi; Sakata, Ryuzo; Inoue, Kanji

2011-01-01

Open surgical repair is a traditional treatment for patients with thoracic aortic aneurysms. Despite recent advances in surgical techniques and anesthetic management, the surgical repair of thoracic aortic aneurysms is still associated with significant mortality and morbidity. Endovascular aneurysm repair of thoracic aortic aneurysms is emerging as an alternative method for repair in selected patients. Although endovascular stent grafting is less invasive than open surgical repair, involvement of branch vessels and precipitous curvature of the aortic arch limits the application of stent grafting. Inoue stent graft system consists of soft nitinol ring-type stent which enables very flexible stent graft, and it can well comply with the precipitous curvature of the aortic arch. The system also provides a stent graft with a side branch to manage the left subclavian artery. This system does not require the surgical revascularization of the left subclavian artery. In this report, we show the feasibility and possibility of Inoue stent graft system to manage the aortic arch aneurysm.

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

PubMed

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.

Time Sequence Evaluation of Biliary Stent Occlusion by Dissection Analysis of Retrieved Stents.

PubMed

Kwon, Chang-Il; Gromski, Mark A; Sherman, Stuart; Easler, Jeffrey J; El Hajj, Ihab I; Watkins, James; Fogel, Evan L; McHenry, Lee; Lehman, Glen A

2016-08-01

Multiple factors can affect the occlusion of plastic stents. Previous data demonstrate that side holes may induce more biofilm formation probably via microturbulence and bile flow disturbances that could lead to occlusion. These results, however, have not been replicated in subsequent clinical studies with different methods. The objective of this study is to evaluate the physical characteristics of plastic stent occlusion over time. This is a plastic stent sequential analysis study. Biliary stents removed via ERCP from February 24, 2015, to June 2, 2015, were included. One hundred and forty-eight retrieved straight-type plastic stents were longitudinally cut by a custom-made cutting device. These dissected stents were then evaluated in detail with regard to the location of stent occlusion and the stent patency period. Location of stent occlusive debris was the primary outcome in this study. Biofilm formations and occlusions by debris were sequentially but separately tallied. Biofilm formations were initially seen around the side hole areas within 30 days and spread to the entire stent by 60 days. Then, occlusion process by debris was mainly initiated by 80 days and progressed to full occlusion by median of 90 days. Although some occlusions were also observed around the side hole areas within 30 days, affected areas were more widely observed after biofilm formation. This study is the first to attempt to describe the distribution of stent occlusions over time. These observations may help guide future stent development.

Late peripheral stent thrombosis due to stent fracture, vigorous exercise and hyporesponsiveness to clopidogrel.

PubMed

Linnemann, Birgit; Thalhammer, Axel; Wolf, Zsuzsanna; Tirneci, Vanessa; Vogl, Thomas J; Edelgard Lindhoff-Last, And

2012-03-01

Late peripheral arterial stent thrombosis usually occurs due to haemodynamically relevant in-stent restenosis. However, late stent thrombosis may be multicausal. We report here the well-documented case of a 69-year-old man with acute thrombosis of the stented superficial femoral artery after a long-distance bicycle tour. Catheter-directed thrombolysis revealed a residual stenosis located at a stent fracture site. In addition, platelet function tests revealed an inadequate platelet response to clopidogrel. In conclusion, stent fracture, strenuous exercise and hyporesponsiveness to clopidogrel may have contributed to the development of late peripheral stent thrombosis.

Percutaneous stent placement for the treatment of malignant biliary obstruction: nitinol versus elgiloy stents.

PubMed

Zurstrassen, Charles Edouard; Bitencourt, Almir Galvão Vieira; Guimaraes, Marcos Duarte; Cavalcante, Aline Cristine Barbosa Santos; Tyng, Chiang Jeng; Amoedo, Mauricio Kauark; Matsushita Junior, João Paulo Kawaoka; Szklaruk, Janio; Marchiori, Edson; Chojniak, Rubens

2017-01-01

This study aimed to compare two self-expanding stents, a nitinol stent and an elgiloy stent, both placed percutaneously, in terms of their efficacy in palliating inoperable malignant biliary obstruction. We retrospectively investigated 99 patients with unresectable malignant biliary obstruction treated with percutaneous placement of a self-expanding metallic stent at our institution between May 2007 and January 2010. Serum bilirubin and liver enzyme levels were measured before and 30 days after stenting. For all procedures using elgiloy or nitinol stents, stent occlusion and patient survival rates were calculated using Kaplan-Meyer analysis. All of the patients showed clinical improvement after stent placement, with no difference between the two groups. In both groups, the occlusion-free survival rate was 67% at 30 days, 37% at 90 days, 25% at 180 days, and 10% at 360 days, with no significant difference in relation to the type of stent. The two stents evaluated showed comparable efficacy for the percutaneous treatment of unresectable biliary malignancy, with good clinical results.

Direct stenting with a combined intravascular ultrasound-coronary stent delivery platform: a feasibility trial.

PubMed

Eeckhout, Eric; Berger, Alexandre; Roguelov, Christan; Lyon, Xavier; Imsand, Christophe; Fivaz-Arbane, Malika; Girod, Grégoire; De Benedetti, Edoardo

2003-08-01

IVUS is considered as the most accurate tool for the assessment of optimal stent deployment. Direct stenting has shown to be a safe, efficient, and resource-saving procedure in selected patients. In a prospective 1-month feasibility trial, a new combined IVUS-coronary stent delivery platform (Josonics Flex, Jomed, Helsingborn, Sweden) was evaluated during direct stenting in consecutive patients considered eligible for direct stenting. The feasibility endpoint was successful stent deployment without any clinical adverse event, while the efficacy endpoint was strategic adaptation according to standard IVUS criteria for optimal stent deployment at the intermediate phase (after a result considered angiographically optimal) and at the end of the intervention (after optimization according to IVUS standards). A total of 16 patients were successfully treated with this device without any major clinical complication. At the intermediate phase, optimal stent deployment was achieved in four patients only, while at the end only one patient had nonoptimal IVUS stent deployment. In particular, the minimal in-stent cross-section area increased from 6.3 +/- 1.2 to 8.3 +/- 2.5 mm(2). These preliminary data demonstrate the feasibility of direct stenting with a combined IVUS-stent catheter in selected patients and confirm the results from larger randomized trials on the impact of IVUS on strategic adaptations during coronary stent placement. Copyright 2003 Wiley-Liss, Inc.

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

PubMed

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.

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.

PubMed

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.

High single-session success rate of endoscopic bilateral stent-in-stent placement with modified large cell Niti-S stents for malignant hilar biliary obstruction.

PubMed

Kogure, Hirofumi; Isayama, Hiroyuki; Nakai, Yousuke; Tsujino, Takeshi; Matsubara, Saburo; Yashima, Yoko; Ito, Yukiko; Hamada, Tsuyoshi; Takahara, Naminatsu; Miyabayashi, Koji; Mizuno, Suguru; Mohri, Dai; Kawakubo, Kazumichi; Sasaki, Takashi; Yamamoto, Natsuyo; Hirano, Kenji; Sasahira, Naoki; Tada, Minoru; Koike, Kazuhiko

2014-01-01

Endoscopic bilateral self-expandable metallic stent (SEMS) placement in a stent-in-stent method for malignant hilar biliary obstruction is technically challenging. Technical difficulties in the initial placement and reinterventions for stent occlusion are disadvantages inherent to this stent-in-stent method. We previously reported the feasibility of Niti-S large cell D-type biliary stents (LCD). This multicenter prospective consecutive study evaluated the efficacy of bilateral SEMS placement using modified LCD with large and uniform cells, a slimmer delivery system and high radial force. From July 2010 to June 2011, 26 consecutive patients with unresectable malignant hilar biliary obstruction underwent endoscopic bilateral placement of modified LCD in a stent-in-stent method at three tertiary hospitals. Ten patients had gallbladder cancer, eight had cholangiocarcinoma, four had lymph node metastasis, two had intrahepatic cholangiocarcinoma, and two had liver metastasis. Single-session and final technical success rate was 96% and 100%, respectively. Functional success rate was 89%. Stent occlusion occurred in 11 patients (42%) because of sludge (n = 7) or tumor ingrowth (n = 4). Endoscopic bilateral reintervention was technically easy and successful: six patients had stent clearance by balloon sweeping and five had plastic stent placement. According to Kaplan-Meier analysis, median survival and stent patency were 220 days and 157 days, respectively. Modified LCD achieved a high technical success rate both in the initial stent-in-stent placement and in bilateral reinterventions in patients with malignant hilar biliary obstruction. © 2013 The Authors. Digestive Endoscopy © 2013 Japan Gastroenterological Endoscopy Society.

A new polymer-free drug-eluting stent with nanocarriers eluting sirolimus from stent-plus-balloon compared with bare-metal stent and with biolimus A9 eluting stent in porcine coronary arteries

PubMed Central

Galon, Micheli Z.; Gutierrez, Paulo S.; Sojitra, Prakash; Vyas, Ashwin; Doshi, Manish; Lemos, Pedro A.

2015-01-01

Background Permanent polymers in first generation drug-eluting stent (DES) have been imputed to be a possible cause of persistent inflammation, remodeling, malapposition and late stent thrombosis. We aim to describe the in vivo experimental result of a new polymer-free DES eluting sirolimus from stent-plus-balloon (Focus np stent, Envision Scientific) compared with a bare-metal stent (BMS) (Amazonia CroCo, Minvasys) and with a biolimus A9 eluting stent (Biomatrix, Biosensors). Methods In 10 juvenile pigs, 23 coronary stents were implanted in the coronary arteries (8 Amazonia CroCo, 8 Focus np, and 7 Biomatrix). At 28-day follow-up, optical coherence tomography (OCT) and histology were used to evaluate neointimal hyperplasia and healing response. Results According to OCT analysis, Focus np stents had a greater lumen area and less neointimal hyperplasia response than BMS and Biomatrix had. Histomorphometry results showed less neointimal hyperplasia in Focus np than in BMS. Histology showed a higher fibrin deposition in Biomatrix stent compared to Focus np and BMS. Conclusions The new polymer-free DES with sirolimus eluted from stent-plus-balloon demonstrated safety and reduced neointimal proliferation compared with the BMS and Biomatrix stents at 28-day follow-up in this porcine coronary model. This new polymer-free DES is promising and warrants further clinical studies. PMID:25984451

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

PubMed

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 < .001) and less bilateral femoral access (55% vs 100%; P < .001). Two patients in the single-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.

Sensor to detect endothelialization on an active coronary stent

PubMed Central

2010-01-01

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. PMID:21050471

Mechanical Characteristics of Composite Knitted Stents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tokuda, Takanori, E-mail: tkdtknr@gmail.com; Shomura, Yuzo; Tanigawa, Noboru

2009-09-15

We used metal wires and fibers to fabricate a composite knitted stent and then compare the mechanical characteristics of this stent with those of a pure metallic stent of the same construction in order to develop a stent that offers a comparable degree of expandability as metallic stents but can be used for highly curved lesions that cannot be treated using metallic stents. We fabricated two types of composite knitted stent (N-Z stents), using nitinol wire with a diameter of 0.12 mm and polypara-phenylene-benzobisoxazole (PBO) multifilament fiber (Zyron AS; Toyobo, Osaka, Japan). Stents were knitted into a cylindrical shape usingmore » the same textile pattern as a Strecker stent. Two loop lengths (L) of nitinol wire were used in the N-Z stents: L = 1.84 mm (N-Z stent L = 1.84) and L = 2.08 mm (N-Z stent L = 2.08). For the sake of comparison, we fabricated a metallic stent of nitinol using the same textile pattern (N-N stent L = 1.92). We applied a radial compression force diametrically to each stent and applied a bending force diametrically at the free end of a stent with one end fixed in order to evaluate the relationship between stent elasticity and load values. In addition, we macroscopically evaluated the generation of kinks when the stent was bent 180{sup o}. The radial compressive force when the stent diameter was reduced by 53% was 6.44 N in the case of N-Z stent L = 1.84, 6.14 N in the case of N-Z stent L = 2.08, and 4.96 N in the case of N-N stent L = 1.92 mm. The composite stent had a radial compressive force higher than that of a metallic stent. The restoring force to longitudinal direction at a 90{sup o} bending angle was 0.005 N for N-Z stent L = 1.84, 0.003 N for N-Z stent L = 2.08, and 0.034 N for N-N stent L = 1.92. The restoring force of the composite stent was significantly lower. Finally, the composite stent generated no definitive kinks at a bending angle of 180{sup o}, regardless of loop length. However, the N-N stent clearly produced kinks

Silicone-covered biodegradable magnesium-stent insertion in the esophagus: a comparison with plastic stents.

PubMed

Zhu, Yue-Qi; Yang, Kai; Edmonds, Laura; Wei, Li-Ming; Zheng, Reila; Cheng, Ruo-Yu; Cui, Wen-Guo; Cheng, Ying-Sheng

2017-01-01

We determined the feasibility of, and tissue response to silicone-covered biodegradable magnesium- and plastic-stent insertion into the esophagus in rabbits. The mechanical compression-recovery characteristics and degradation behaviors of the magnesium stent were investigated in vitro . A total of 45 rabbits were randomly divided into a magnesium- ( n = 15) and a plastic- ( n = 15) stent group, and underwent stent insertion into the lower third of the esophagus under fluoroscopic guidance; a control group ( n = 15) did not undergo the intervention. Esophagography was performed at 1, 2, and 4 weeks. Five rabbits in each group were euthanized at each time point for histological examination. Silicone-covered magnesium stents showed similar radial force to plastic stents ( p > 0.05). The magnesium stents degraded rapidly in an acidic solution, but 90.2% ± 3.1% of the residual mass was maintained after a 2-week degradation in a solution with a pH of 4.0. All stent insertions were well tolerated. Magnesium stents migrated in six rabbits (one at 1 week, one at 2 weeks and four at 4 weeks), and plastic stents migrated in three rabbits (one at 2 weeks and two at 4 weeks; p > 0.05). Esophageal wall remodeling (thinner epithelial and smooth muscle layers) was similar in both stented groups ( p > 0.05), and the esophagus wall was found to be significantly thinner in the stented groups than in the control group ( p < 0.05). Esophageal injury and collagen deposition following stent insertion were similar and did not differ from the control group ( p > 0.05). Esophageal silicone-covered magnesium stents provided reliable support for at least 2 weeks, with acceptable migration rates and without causing severe injury or tissue reaction compared with plastic stents.

Silicone-covered biodegradable magnesium-stent insertion in the esophagus: a comparison with plastic stents

PubMed Central

Zhu, Yue-Qi; Yang, Kai; Edmonds, Laura; Wei, Li-Ming; Zheng, Reila; Cheng, Ruo-Yu; Cui, Wen-Guo; Cheng, Ying-Sheng

2016-01-01

Background: We determined the feasibility of, and tissue response to silicone-covered biodegradable magnesium- and plastic-stent insertion into the esophagus in rabbits. Methods: The mechanical compression–recovery characteristics and degradation behaviors of the magnesium stent were investigated in vitro. A total of 45 rabbits were randomly divided into a magnesium- (n = 15) and a plastic- (n = 15) stent group, and underwent stent insertion into the lower third of the esophagus under fluoroscopic guidance; a control group (n = 15) did not undergo the intervention. Esophagography was performed at 1, 2, and 4 weeks. Five rabbits in each group were euthanized at each time point for histological examination. Results: Silicone-covered magnesium stents showed similar radial force to plastic stents (p > 0.05). The magnesium stents degraded rapidly in an acidic solution, but 90.2% ± 3.1% of the residual mass was maintained after a 2-week degradation in a solution with a pH of 4.0. All stent insertions were well tolerated. Magnesium stents migrated in six rabbits (one at 1 week, one at 2 weeks and four at 4 weeks), and plastic stents migrated in three rabbits (one at 2 weeks and two at 4 weeks; p > 0.05). Esophageal wall remodeling (thinner epithelial and smooth muscle layers) was similar in both stented groups (p > 0.05), and the esophagus wall was found to be significantly thinner in the stented groups than in the control group (p < 0.05). Esophageal injury and collagen deposition following stent insertion were similar and did not differ from the control group (p > 0.05). Conclusions: Esophageal silicone-covered magnesium stents provided reliable support for at least 2 weeks, with acceptable migration rates and without causing severe injury or tissue reaction compared with plastic stents. PMID:28286555

An Update to Hepatobiliary Stents

PubMed Central

Moy, Brian T.; Birk, John W.

2015-01-01

Endoscopic stent placement is a common primary management therapy for benign and malignant biliary strictures. However, continuous use of stents is limited by occlusion and migration. Stent technology has evolved significantly over the past two decades to reduce these problems. The purpose of this article is to review current guidelines in managing malignant and benign biliary obstructions, current endoscopic techniques for stent placement, and emerging stent technology. What began as a simple plastic stent technology has evolved significantly to include uncovered, partially covered, and fully covered self-expanding metal stents (SEMS) as well as magnetic, bioabsorbable, drug-eluting, and antireflux stents.1 PMID:26357636

Management of occluded metal stents in malignant biliary obstruction: similar outcomes with second metal stents compared to plastic stents

PubMed Central

Shah, Tilak; Desai, Svetang; Haque, Mahfuzul; Dakik, Hassan; Fisher, Deborah

2013-01-01

Background Covered or uncovered self expandable metallic stents (SEMS) placed in patients with malignant biliary obstruction can occlude in 19–40%, but optimal management is unclear. Aim We sought to summarize current evidence regarding management of occluded SEMS in patients with malignant biliary obstruction. Methods Two investigators independently searched Pubmed, Embase, and Web of Science using pre-defined search criteria, and reviewed bibliographies of included studies. Data were independently abstracted by two investigators, and analyzed using RevMan. We compared strategies of second SEMS versus plastic stents with respect to the following outcomes: rate of second stent re-occlusion, duration of second stent patency, and survival. Results Ten retrospective studies met inclusion criteria for the systematic review. Management options described were placement of an uncovered SEMS (n=125), covered SEMS (n=106), plastic stent (n=135), percutaneous biliary drain (n=7), mechanical cleaning (n=18), or microwave coagulation (n=7). Relative risk of re-occlusion was not significantly different in patients with second SEMS compared to plastic stents (RR 1.24, 95% CI 0.92, 1.67, I2= 0, p 0.16). Duration of second stent patency was not significantly different between patients who received second SEMS versus plastic stents (weighted mean difference 0.46, 95% CI −0.30, 1.23, I2=83%). Survival was not significantly different among patients who received plastic stents versus SEMS (weighted mean difference −1.13, 95% CI −2.33, 0.07, I2 86%, p 0.07). Conclusions Among patients with malignant biliary obstruction and occluded SEMS, available evidence suggests a strategy of placing a plastic stent may be as effective as second SEMS. Limitations of these findings were that all studies were retrospective and heterogeneity between studies was detected for two of the outcomes. PMID:22732833

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

PubMed

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

2017-05-15

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. 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. 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). 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.

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

PubMed Central

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

Biodegradable airway stents in infants - Potential life-threatening pitfalls.

PubMed

Sztanó, B; Kiss, G; Márai, K; Rácz, G; Szegesdi, I; Rácz, K; Katona, G; Rovó, L

2016-12-01

The solution of severe tracheobronchial obstructions in early childhood means a great challenge. Biodegradable stents were intended to be a minimally invasive temporary solution which may decrease the number of interventions and limit the possible complications of stenting procedures. However, our first experiences have brought out a new, - especially in childhood - potentially life-threatening complication of this concept. Five SX-ELLA biodegradable polydioxanone stents was applied in three patients because of severe tracheobronchial obstruction: congenital tracheomalacia (7 day-old), acquired tracheomalacia (10 month-old), and congenital trachea-bronchomalacia (10 month-old). The breathing of all children improved right after the procedure. We observed degradation of the stent from the 5th postoperative week which resulted in large intraluminar fragments causing significant airway obstruction: one patient died of severe pneumonia, the other baby required urgent bronchoscopy to remove the obstructing 'foreign body' from the trachea. In the third case repeated stent placements successfully maintained the tracheal lumen. Polydioxanone stents may offer an alternative to metallic or silastic stents for collapse or external compression of the trachea in children; however, large decaying fragments mean a potential risk especially in the small size pediatric airway. The fragmentation of the stent, which generally starts in the 4-6 postoperative weeks, may create large sharp pieces. These may be anchored to the mucosa and covered by crust leading to obstruction. As repeated interventions are required, we do not consider the application of biodegradable stents unambiguously advantageous. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Stenting for symptomatic vertebral artery stenosis: The Vertebral Artery Ischaemia Stenting Trial.

PubMed

Markus, Hugh S; Larsson, Susanna C; Kuker, Wilhelm; Schulz, Ursula G; Ford, Ian; Rothwell, Peter M; Clifton, Andrew

2017-09-19

To compare in the Vertebral Artery Ischaemia Stenting Trial (VIST) the risks and benefits of vertebral angioplasty and stenting with best medical treatment (BMT) alone for symptomatic vertebral artery stenosis. VIST was a prospective, randomized, open-blinded endpoint clinical trial performed in 14 hospitals in the United Kingdom. Participants with symptomatic vertebral stenosis ≥50% were randomly assigned (1:1) to vertebral angioplasty/stenting plus BMT or to BMT alone with randomization stratified by site of stenosis (extracranial vs intracranial). Because of slow recruitment and cessation of funding, recruitment was stopped after 182 participants. Follow-up was a minimum of ≥1 year for each participant. Three patients did not contribute any follow-up data and were excluded, leaving 91 patients in the stent group and 88 in the medical group. Mean follow-up was 3.5 (interquartile range 2.1-4.7) years. Of 61 patients who were stented, stenosis was extracranial in 48 (78.7%) and intracranial in 13 (21.3%). No periprocedural complications occurred with extracranial stenting; 2 strokes occurred during intracranial stenting. The primary endpoint of fatal or nonfatal stroke occurred in 5 patients in the stent group vs 12 in the medical group (hazard ratio 0.40, 95% confidence interval 0.14-1.13, p = 0.08), with an absolute risk reduction of 25 strokes per 1,000 person-years. The hazard ratio for stroke or TIA was 0.50 ( p = 0.05). Stenting in extracranial stenosis appears safe with low complication rates. Large phase 3 trials are required to determine whether stenting reduces stroke risk. ISRCTN95212240. This study provides Class I evidence that for patients with symptomatic vertebral stenosis, angioplasty with stenting does not reduce the risk of stroke. However, the study lacked the precision to exclude a benefit from stenting. Copyright © 2017 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

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

PubMed

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.

Biomechanical analysis on stent materials used as cardiovascular implants

NASA Astrophysics Data System (ADS)

Kumar, Vasantha; Ramesha, C. M.; Sajjan, Sudheer S.

2018-04-01

Atherosclerosis is the most common cause of death in the world, accounting for 48% of all deaths in the world. Atherosclerosis, also known as coronary artery disease occurs when excess cholesterol attaches itself to the walls of blood vessels. Coronary stent implantation is one of the most important procedures to treating coronary artery disease such atherosclerosis. Due to its efficiency, flexibility and simplicity, the use of coronary stents procedures has increased rapidly. In order to have better output of stent implantation, it is needed to study and analyze the biomechanical behavior of this device before manufacturing and put into use. Biomaterials are commonly used for medical application in cardiovascular stent implantation. A biomaterial is a non-viable material used as medical implant, so it is intended to interact with biological system. In this paper, an explicit dynamic analysis is used for analyzing the biomechanical behavior of cardiovascular stent by using finite element analysis tool, ABAQUS 6.10. Results showed that a best suitable biomaterial for cardiovascular stent implants, which exhibits an outstanding biocompatibility and biomechanical characteristics will be aimed at which will be quite useful to the human beings worldwide.

The conical stent in coronary artery improves hemodynamics compared with the traditional cylindrical stent.

PubMed

Yu, Yi; Zhou, Yujie; Ma, Qian; Jia, Shuo; Wu, Sijing; Sun, Yan; Liu, Xiaoli; Zhao, Yingxin; Liu, Yuyang; Shi, Dongmei

2017-01-15

This study sought to explore the efficacy of the conical stent implantation in the coronary artery by comparing the effects of cylindrical and conical stents on wall shear stress (WSS) and velocity of flow and fractional flow reserve (FFR). The traditional cylindrical stent currently used in the percutaneous coronary intervention (PCI) has a consistent diameter, which does not match the physiological change of the coronary artery. On the contrary, as a new patent, the conical stent with tapering lumen is consistent with the physiological change of vascular diameter. However, the effect of the conical stent implantation on the coronary hemodynamics remains unclear. The coronary artery, artery stenosis and two stent models were established by Solidworks software. All models were imported into the computational fluid dynamics (CFD) software ANSYS ICEM-CFD to establish the fluid model. After the boundary conditions were set, CFD analysis was proceeded to compare the effects of two stent implantation on the change of WSS, velocity of flow and FFR. Hemodynamic indexes including FFR, blood flow velocity distribution (BVD) and WSS were improved by either the cylindrical or the conical stent implantation. However, after the conical stent implantation, the change of FFR seemed to be slower and more homogenous; the blood flow velocity was more appropriate without any obvious blood stagnation and direction changes; the WSS after the conical stent implantation was uniform from the proximal to distal side of the stent. Compared with the cylindrical stent, the conical stent implantation in the coronary artery can make the changes of vascular hemodynamic more closer to the physiological condition, which can reduce the incidence of intra-stent restenosis and thrombosis, thus making it more suitable for PCI therapy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

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

PubMed

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.

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

PubMed Central

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

2016-01-01

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

Meta-Analysis of Stenting versus Non-Stenting for the Treatment of Ureteral Stones

PubMed Central

Wang, Hai; Man, Libo; Li, Guizhong; Huang, Guanglin; Liu, Ning; Wang, Jianwei

2017-01-01

Background and aim Ureteroscopic lithotripsy (URL) and extracorporeal shock wave lithotripsy (ESWL) are two widely used methods for the treatment of ureteral stones. The need for ureteral stenting during these procedures is controversial. In this meta-analysis, we evaluated the benefits and disadvantages of ureteral stents for the treatment of ureteral stones. Methods Databases including PubMed, Embase and Cochrane library were selected for systematic review of randomized controlled trials (RCTs) comparing outcomes with or without stenting during URL and ESWL. Meta-analysis was performed using RevMan 5.3 and STATA 13.0 software. Results We identified 22 RCTs comparing stenting and non-stenting. The stented group was associated with longer operation time (WMD: 4.93; 95% CI: 2.07 to 7.84; p < 0.001), lower stone-free rate (OR: 0.55; 95% CI: 0.34 to 0.89; p = 0.01). In terms of complications, the incidence of hematuria (OR: 3.68; 95% CI: 1.86 to 7.29; p < 0.001), irritative urinary symptoms (OR: 4.40; 95% CI: 2.19 to 9.10; p < 0.001), urinary infection (OR: 2.23; 95% CI: 1.57 to 3.19; p < 0.001), and dysuria (OR: 3.90; 95% CI: 2.51 to 6.07; p < 0.001) were significantly higher in the stented group. No significant differences in visual analogue score (VAS), stricture formation, fever, or hospital stay were found between stenting and non-stenting groups. The risk of unplanned readmissions (OR: 0.63; 95% CI: 0.41 to 0.97; p = 0.04) was higher in the non-stented group. Conclusions Our analysis showed that stenting failed to improve the stone-free rate, and instead, it resulted in additional complications. However, ureteral stents are valuable in preventing unplanned re-hospitalization. Additional randomized controlled trials are still required to corroborate our findings. PMID:28068364

Percuflex Helical Ureteral Stents Significantly Reduce Patient Analgesic Requirements Compared to Control Stents.

PubMed

Chew, Ben H; Rebullar, Karla A; Harriman, David; McDougall, Elspeth; Paterson, Ryan F; Lange, Dirk

2017-12-01

Ureteral stent symptoms are experienced by the majority of patients with ureteral stents. No one stent or technology has shown a clear advantage. The Helical™ stent, a spirally cut stent made of proprietary Percuflex™ material, was designed to conform to the shape of the ureter and better accommodate patient movement. We prospectively sought to compare unscheduled visits, analgesic use, and pain scores in patients who received a Percuflex Helical ureteral stent following ureteroscopy compared to a historical control group. Fifteen (n = 15) patients undergoing ureteroscopy for the treatment of kidney stones were consented for study. A Percuflex Helical ureteral stent was inserted after treating the urinary stone. The historical control group consisted of 30 patients, from a previous (ketorolac eluting) ureteral stent study utilizing the same protocol and clinical monitoring forms, who received a regular Percuflex ureteral stent. The control patients were matched by age and sex. The primary study outcome was to compare unscheduled visits. Secondary outcomes included comparison of Visual Pain Analog Scale (VPAS) scores and analgesic use between the two groups. There were no differences in the gender, age, BMI, or stone characteristics between groups. Both groups underwent retrograde ureteroscopy using holmium:YAG laser lithotripsy and stone fragmentation. There was a significant reduction in the amount of analgesics required in the Helical stent group (4.4 ± 7.99 mg morphine equivalents) compared to controls (16.75 ± 18.31 mg, p = 0.0035) to achieve similar VPAS scores. There was no difference in unscheduled visits (20%) or VPAS scores (13.84 ± 13.68 helical vs 14.29 ± 11.58 control, p = 0.7910) between groups. Patients who received a Percuflex Helical ureteral stent required significantly fewer analgesics than those who received a Percuflex stent and both had equivalent pain scores.

In vitro hemocompatibility and cytocompatibility of dexamethasone-eluting PLGA stent coatings

NASA Astrophysics Data System (ADS)

Zhang, Jiang; Liu, Yang; Luo, Rifang; Chen, Si; Li, Xin; Yuan, Shuheng; Wang, Jin; Huang, Nan

2015-02-01

Drug-eluting stents (DESs) have been an important breakthrough for interventional cardiology applications since 2002. Though successful in reducing restenosis, some adverse clinical problems still emerged, which were mostly caused by the bare-metal stents and non-biodegradable polymer coatings, associated with the delayed endothelialization process. In this study, dexamethasone-loaded poly (lactic-co-glycolic acid) (PLGA) coatings were developed to explore the potential application of dexamethasone-eluting stents. Dexamethasone-eluting PLGA stents were prepared using ultrasonic atomization spray method. For other tests like stability and cytocompatibility and hemocompatibility tests, dexamethasone loaded coatings were deposited on 316L SS wafers. Fourier transform-infrared spectroscopy (FT-IR) results demonstrated that there was no chemical reaction between PLGA and dexamethasone. The balloon expansion experiment and surface morphology observation suggested that the stent coatings were smooth and uniform, and could also withstand the compressive and tensile strains imparted without cracking after stent expansion. The drug release behavior in vitro indicated that dexamethasone existed burst release within 1 day, but it presented linear release characteristics after 6 days. In vitro platelets adhesion, activation test and APTT test were also done, which showed that after blending dexamethasone into PLGA, the hemocompatibility was improved. Besides, dexamethasone and dexamethasone-loaded PLGA coatings could significantly inhibit the attachment and proliferation of smooth muscle cells.

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

PubMed

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.

Stent thrombosis with drug-eluting and bare-metal stents: evidence from a comprehensive network meta-analysis.

PubMed

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

Bioabsorbable coronary stents--are these the next big thing in coronary angioplasty?

PubMed

Balla, Sudarshan; Aggarwal, Kul; Nistala, Ravi

2010-06-01

The role of percutaneous coronary intervention (PCI) in the treatment of coronary artery disease has grown at an astronomical pace. Drug eluting stents (DES) offer advantages over bare metal stents (BMS) such as reduction in early in-stent restenosis rates. However, they have disadvantages like from increased late stent thrombosis when compared with BMS. Furthermore, recent data suggest endothelial dysfunction in the DES stented segments of the arteries. Currently, bioabsorbable stents are under development to avert the complications of DES such as stent thrombosis via degradation of the stent over time. The hypothetical advantage of leaving behind a natural vessel and restoring vasoreactivity may be the almost normal physiology which can be achieved after an intervention with a stent. The ABSORB and the PROGRESS AMS are two of the recent clinical trials that have looked at the outcomes of using bioabsorbable stents. So far, data from these and other studies has yielded mixed results in terms of angiographic and clinical outcomes. Newer stents such as REVA and WHISPER are presently being tested in preclinical and clinical trials. The landscape for bioabsorbable stents is constantly evolving through continued improvisation on existing technology and emergence of new technology. Large scale randomized trials are still needed with adequate long term follow-up for safety and benefits to have mainstream application in coronary artery disease, bioabsorbable stents are a promising innovation in the field of PCI. We review some of the patents and the data that is emerging on bioabsorbable stents in addition to currently ongoing clinical trials.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, Hwan-Hoon, E-mail: chungmic@korea.ac.kr; Lee, Seung Hwa; Cho, Sung Bum

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 sixmore » 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.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2000-11-15

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.

Advances in drug eluting stents – focus on the Endeavor® zotarolimus stent

PubMed Central

Bridges, Jonathan; Cutlip, Donald

2009-01-01

Coronary artery disease remains one of the leading causes of death in the United States. Over the last 30 years, the development of coronary artery angioplasty and stenting has drastically reduced mortality during acute coronary syndromes while also reducing symptoms of chronic coronary artery disease. Unfortunately, the placement of stents in a coronary artery can be complicated by in-stent thrombosis or restenosis. In 2003–2004, a new generation of stents was introduced to the market with the goal of reducing the rate of restenosis. These stents, called drug eluting stents (DES), are coated with a pharmacological agent designed to reduce the neointimal hyperplasia associated with restenosis. Within a year, approximately 80% of all percutaneous coronary interventions performed within the US involved placement of a DES. In 2006, a controversy arose about the possibility of a statistically significant increased risk of acute stent thrombosis associated with DES especially when used for an “off label” indication. This risk was attributed to delayed endothelization. This controversy has led to a reduction in the use of DES along with longer use of dual platelet inhibition with aspirin and clopidogrel. Recently Medtronic introduced a new DES to the market called the Endeavor® stent – a zotarolimus eluting stent. PMID:22915908

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

PubMed

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.

Fabrication of Small Caliber Stent-grafts Using Electrospinning and Balloon Expandable Bare Metal Stents.

PubMed

Uthamaraj, Susheil; Tefft, Brandon J; Jana, Soumen; Hlinomaz, Ota; Kalra, Manju; Lerman, Amir; Dragomir-Daescu, Dan; Sandhu, Gurpreet S

2016-10-26

Stent-grafts are widely used for the treatment of various conditions such as aortic lesions, aneurysms, emboli due to coronary intervention procedures and perforations in vasculature. Such stent-grafts are manufactured by covering a stent with a polymer membrane. An ideal stent-graft should have a biocompatible stent covered by a porous, thromboresistant, and biocompatible polymer membrane which mimics the extracellular matrix thereby promoting injury site healing. The goal of this protocol is to manufacture a small caliber stent-graft by encapsulating a balloon expandable stent within two layers of electrospun polyurethane nanofibers. Electrospinning of polyurethane has been shown to assist in healing by mimicking native extracellular matrix, thereby promoting endothelialization. Electrospinning polyurethane nanofibers on a slowly rotating mandrel enabled us to precisely control the thickness of the nanofibrous membrane, which is essential to achieve a small caliber balloon expandable stent-graft. Mechanical validation by crimping and expansion of the stent-graft has shown that the nanofibrous polyurethane membrane is sufficiently flexible to crimp and expand while staying patent without showing any signs of tearing or delamination. Furthermore, stent-grafts fabricated using the methods described here are capable of being implanted using a coronary intervention procedure using standard size guide catheters.

Fabrication of Small Caliber Stent-grafts Using Electrospinning and Balloon Expandable Bare Metal Stents

PubMed Central

Uthamaraj, Susheil; Tefft, Brandon J.; Jana, Soumen; Hlinomaz, Ota; Kalra, Manju; Lerman, Amir; Dragomir-Daescu, Dan; Sandhu, Gurpreet S.

2016-01-01

Stent-grafts are widely used for the treatment of various conditions such as aortic lesions, aneurysms, emboli due to coronary intervention procedures and perforations in vasculature. Such stent-grafts are manufactured by covering a stent with a polymer membrane. An ideal stent-graft should have a biocompatible stent covered by a porous, thromboresistant, and biocompatible polymer membrane which mimics the extracellular matrix thereby promoting injury site healing. The goal of this protocol is to manufacture a small caliber stent-graft by encapsulating a balloon expandable stent within two layers of electrospun polyurethane nanofibers. Electrospinning of polyurethane has been shown to assist in healing by mimicking native extracellular matrix, thereby promoting endothelialization. Electrospinning polyurethane nanofibers on a slowly rotating mandrel enabled us to precisely control the thickness of the nanofibrous membrane, which is essential to achieve a small caliber balloon expandable stent-graft. Mechanical validation by crimping and expansion of the stent-graft has shown that the nanofibrous polyurethane membrane is sufficiently flexible to crimp and expand while staying patent without showing any signs of tearing or delamination. Furthermore, stent-grafts fabricated using the methods described here are capable of being implanted using a coronary intervention procedure using standard size guide catheters. PMID:27805589

Endoscopic dacryocystorhinostomy without silicone stent.

PubMed

Yeon, Je Yeob; Shim, Woo Sub

2012-06-01

In nasolacrimal duct (NLD) obstruction patients that undergo endoscopic dacryocystorhinostomy (DCR), creation of a patent rhinostomy with adequate epithelialization can be accomplished without a stent. However, in common canalicular obstruction patients, a silicone stent seems to have a beneficial role and to bear more favorable results. The aim of this study was to evaluate the surgical outcome of endoscopic DCR without the use of a silicone stent. In all, 36 patients (41 eyes) who underwent endoscopic DCR were enrolled in this study. The patients were classified into a DCR with silicone stent group and a DCR without silicone stent group. Then each of the groups was subdivided into common canalicular obstruction group and NLD obstruction group. Surgical outcomes were evaluated by postoperative symptom improvement and patency of the rhinostomy under nasal endoscopic exam. The epiphora was improved in 84.2% of the silicone stent group and 81.8% of the non-silicone stent group. Categorized by the level of obstruction, in common canalicular obstruction, the success rate was 84.5% (11/13) in the silicone stent group and 57.1% (4/7) in the no stent group. In NLD obstruction, the success rate was 83.0% (5/6) in the silicone stent group and 93.3% (14/15) in the no stent group.

Predictive factors for the failure of endoscopic stent-in-stent self-expandable metallic stent placement to treat malignant hilar biliary obstruction.

PubMed

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.

Fabrication of a silver particle-integrated silicone polymer-covered metal stent against sludge and biofilm formation and stent-induced tissue inflammation

PubMed Central

Lee, Tae Hoon; Jang, Bong Seok; Jung, Min Kyo; Pack, Chan Gi; Choi, Jun-Ho; Park, Do Hyun

2016-01-01

To reduce tissue or tumor ingrowth, covered self-expandable metal stents (SEMSs) have been developed. The effectiveness of covered SEMSs may be attenuated by sludge or stone formation or by stent clogging due to the formation of biofilm on the covering membrane. In this study, we tested the hypothesis that a silicone membrane containing silver particles (Ag-P) would prevent sludge and biofilm formation on the covered SEMS. In vitro, the Ag-P-integrated silicone polymer-covered membrane exhibited sustained antibacterial activity, and there was no definite release of silver ions from the Ag-P-integrated silicone polymer membrane at any time point. Using a porcine stent model, in vivo analysis demonstrated that the Ag-P-integrated silicone polymer-covered SEMS reduced the thickness of the biofilm and the quantity of sludge formed, compared with a conventional silicone-covered SEMS. In vivo, the release of silver ions from an Ag-P-integrated silicone polymer-covered SEMS was not detected in porcine serum. The Ag-P-integrated silicone polymer-covered SEMS also resulted in significantly less stent-related bile duct and subepithelium tissue inflammation than a conventional silicone polymer-covered SEMS. Therefore, the Ag-P-integrated silicone polymer-covered SEMS reduced sludge and biofilm formation and stent-induced pathological changes in tissue. This novel SEMS may prolong the stent patency in clinical application. PMID:27739486

Fabrication of a silver particle-integrated silicone polymer-covered metal stent against sludge and biofilm formation and stent-induced tissue inflammation.

PubMed

Lee, Tae Hoon; Jang, Bong Seok; Jung, Min Kyo; Pack, Chan Gi; Choi, Jun-Ho; Park, Do Hyun

2016-10-14

To reduce tissue or tumor ingrowth, covered self-expandable metal stents (SEMSs) have been developed. The effectiveness of covered SEMSs may be attenuated by sludge or stone formation or by stent clogging due to the formation of biofilm on the covering membrane. In this study, we tested the hypothesis that a silicone membrane containing silver particles (Ag-P) would prevent sludge and biofilm formation on the covered SEMS. In vitro, the Ag-P-integrated silicone polymer-covered membrane exhibited sustained antibacterial activity, and there was no definite release of silver ions from the Ag-P-integrated silicone polymer membrane at any time point. Using a porcine stent model, in vivo analysis demonstrated that the Ag-P-integrated silicone polymer-covered SEMS reduced the thickness of the biofilm and the quantity of sludge formed, compared with a conventional silicone-covered SEMS. In vivo, the release of silver ions from an Ag-P-integrated silicone polymer-covered SEMS was not detected in porcine serum. The Ag-P-integrated silicone polymer-covered SEMS also resulted in significantly less stent-related bile duct and subepithelium tissue inflammation than a conventional silicone polymer-covered SEMS. Therefore, the Ag-P-integrated silicone polymer-covered SEMS reduced sludge and biofilm formation and stent-induced pathological changes in tissue. This novel SEMS may prolong the stent patency in clinical application.

Future developments in biliary stenting

PubMed Central

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

[Stent-assisted recanalization of femoropopliteal arterial occlusive disease. Influence of stent design on patency rates].

PubMed

Treitl, M; Reiser, M F; Treitl, K M

2016-03-01

Despite enormous technical progress the results of endovascular treatment of the femoropopliteal vasculature are unsatisfactory and its role is still controversially discussed. In the past decade numerous new stent designs have come onto the market but it is unclear whether they have benefits with respect to patency rates. Comparison of published data on patency rates and target lesion revascularization rates after use of different stent designs in the femoropopliteal vasculature. Analysis of 25 published studies and registries from 2006 to 2015 for classical open-cell stents, interwoven stents and partially or fully covered stents. The published data are heterogeneous and comparative studies for different stent designs are completely missing. Over the past decade the patency rates after femoropopliteal stenting could be improved. According to available data stenting of short lesions < 5 cm does not show any benefit compared to isolated balloon angioplasty. Primary stenting is now recommended for intermediate and longer lesions > 6.4 cm. Due to the heterogeneity of published data a clear benefit for a specific stent design is not obvious; however, data for interwoven stents are promising and show a tendency towards improved patency, at least for certain lesions. Randomized controlled comparative trials are needed to confirm this result.

Biliary and pancreatic stenting: Devices and insertion techniques in therapeutic endoscopic retrograde cholangiopancreatography and endoscopic ultrasonography

PubMed Central

Mangiavillano, Benedetto; Pagano, Nico; Baron, Todd H; Arena, Monica; Iabichino, Giuseppe; Consolo, Pierluigi; Opocher, Enrico; Luigiano, Carmelo

2016-01-01

Stents are tubular devices made of plastic or metal. Endoscopic stenting is the most common treatment for obstruction of the common bile duct or of the main pancreatic duct, but also employed for the treatment of bilio-pancreatic leakages, for preventing post- endoscopic retrograde cholangiopancreatography pancreatitis and to drain the gallbladder and pancreatic fluid collections. Recent progresses in techniques of stent insertion and metal stent design are represented by new, fully-covered lumen apposing metal stents. These stents are specifically designed for transmural drainage, with a saddle-shape design and bilateral flanges, to provide lumen-to-lumen anchoring, reducing the risk of migration and leakage. This review is an update of the technique of stent insertion and metal stent deployment, of the most recent data available on stent types and characteristics and the new applications for biliopancreatic stents. PMID:26862364

Process for making electroformed stents

DOEpatents

Hines, Richard A.

2000-02-01

This invention is directed to an expandable stent useful for implantation into an artery or the like. The stents are made using electroforming techniques in which an electrically-conductive mandrel is coated with a suitable resist material, after which the resist is exposed to an appropriate light pattern and frequency so as to form a stent pattern in the resist. The mandrel is then electroplated with a suitable stent material. The mandrel is etched away once a sufficient layer of stent material is deposited, leaving a completed stent.

Open-cell vs. Closed-cell Stent Design Differences in Blood Flow Velocities after Carotid Stenting

PubMed Central

Pierce, Damon S.; Rosero, Eric B; Modrall, J Gregory; Adams-Huet, Beverley; Valentine, R James; Clagett, G Patrick; Timaran, Carlos H

2009-01-01

Objective The differential effect of stent design, i.e. open-cell vs. closed-cell configuration, on carotid velocities detected by duplex ultrasonography (DUS) has not been established. To identify possible stent design differences in carotid velocities, we analyzed our experience with DUS obtained before and immediately after CAS. Methods In a series of 141 CAS procedures performed over a 3 year period, data from the first postinterventional DUS and carotid angiograms were evaluated for each patient. Peak systolic velocities (PSV), end-diastolic velocities (EDV), and internal carotid artery-to-common carotid artery (ICA-CCA) PSV ratios were compared according to stent design. Differences in carotid velocities were analyzed using nonparametric statistical tests. Results Completion angiogram revealed successful revascularization and less that 30% residual stenosis in each case. The 30-day stroke-death rate in this series was 1.6% and was unrelated to stent type. Postintervention DUS was obtained a median of 5 days after CAS (interquartile range [IQR], 1–25 days). Closed-cell stents were used in 41 cases (29%) and open-cell stents in 100 cases (71%). The median PSV was significantly higher for closed-cell stents (122cm/s; IQR, 89–143cm/s) than for open-cell stents (95.9cm/s; IQR, 77.–123) (P=.007). Median EDV (36 vs. 29 cm/s; P=.006) and median ICA-CCA PSV ratio (1.6 vs. 1.1; P=.017) were also significantly higher for closed-cell stents. 45% of closed-cell stents had carotid velocities that exceeded the threshold of 50% stenosis by DUS criteria for a nonstented artery compared to 26% of open-cell stents (P=.04). In fact, closed cell-stents had a 2.2-fold increased risk of yielding abnormally elevated carotid velocities after CAS compared with open-cell stents (odds ratio, 2.2; 95% confidence interval, 1.02–4.9). Conclusions Carotid velocities are disproportionately elevated after CAS with closed-cell stents compared with open-cell stents, which suggests that

Drug eluting biliary stents to decrease stent failure rates: A review of the literature

PubMed Central

Shatzel, Joseph; Kim, Jisoo; Sampath, Kartik; Syed, Sharjeel; Saad, Jennifer; Hussain, Zilla H; Mody, Kabir; Pipas, J Marc; Gordon, Stuart; Gardner, Timothy; Rothstein, Richard I

2016-01-01

Biliary stenting is clinically effective in relieving both malignant and non-malignant obstructions. However, there are high failure rates associated with tumor ingrowth and epithelial overgrowth as well as internally from biofilm development and subsequent clogging. Within the last decade, the use of prophylactic drug eluting stents as a means to reduce stent failure has been investigated. In this review we provide an overview of the current research on drug eluting biliary stents. While there is limited human trial data regarding the clinical benefit of drug eluting biliary stents in preventing stent obstruction, recent research suggests promise regarding their safety and potential efficacy. PMID:26839648

Optical stent inspection of surface texture and coating thickness

NASA Astrophysics Data System (ADS)

Bermudez, Carlos; Laguarta, Ferran; Cadevall, Cristina; Matilla, Aitor; Ibañez, Sergi; Artigas, Roger

2017-02-01

Stent quality control is a critical process. Coronary stents have to be inspected 100% so no defective stent is implanted into a human body. We have developed a high numerical aperture optical stent inspection system able to acquire both 2D and 3D images. Combining a rotational stage, an area camera with line-scan capability and a triple illumination arrangement, unrolled sections of the outer, inner, and sidewalls surfaces are obtained with high resolution. During stent inspection, surface roughness and coating thickness uniformity is of high interest. Due to the non-planar shape of the surface of the stents, the thickness values of the coating need to be corrected with the 3D surface local slopes. A theoretical model and a simulation are proposed, and a measurement with white light interferometry is shown. Confocal and spectroscopic reflectometry showed to be limited in this application due to stent surface roughness. Due to the high numerical aperture of the optical system, only certain parts of the stent are in focus, which is a problem for defect detection, specifically on the sidewalls. In order to obtain fully focused 2D images, an extended depth of field algorithm has been implemented. A comparison between pixel variance and Laplacian filtering is shown. To recover the stack image, two different methods are proposed: maximum projection and weighted intensity. Finally, we also discuss the implementation of the processing algorithms in both the CPU and GPU, targeting real-time 2-Million pixel image acquisition at 50 frames per second.

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

PubMed

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.

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

PubMed

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.

Predictive factors for the failure of endoscopic stent-in-stent self-expandable metallic stent placement to treat malignant hilar biliary obstruction

PubMed Central

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

2017-01-01

AIM To investigate the factors predictive of failure when placing a second biliary self-expandable metallic stents (SEMSs). METHODS 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. RESULTS 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. CONCLUSION A large angle was identified as a predictive factor for failure of stent-in-stent SEMS placement. PMID:28974893

[Numerical modeling of shape memory alloy vascular stent's self-expandable progress and "optimized grid" of stent].

PubMed

Xu, Qiang; Liu, Yulan; Wang, Biao; He, Jin

2008-10-01

Vascular stent is an important medical appliance for angiocardiopathy. Its key deformation process is the expandable progress of stent in the vessel. The important deformation behaviour corresponds to two mechanics targets: deformation and stress. This paper is devoted to the research and development of vascular stent with proprietary intellectual property rights. The design of NiTinol self-expandable stent is optimized by means of finite element software. ANSYS is used to build the finite element simulation model of vascular stent; the molding material is NiTinol shape memory alloy. To cope with the factors that affect the structure of stent, the shape of grid and so on, the self-expanding process of Nitinol stent is simulated through computer. By making a comparison between two kinds of stents with similar grid structure, we present a new concept of "Optimized Grid" of stent.

Experimental models of tracheobronchial stenoses: a useful tool for evaluating airway stents.

PubMed

Marquette, C H; Mensier, E; Copin, M C; Desmidt, A; Freitag, L; Witt, C; Petyt, L; Ramon, P

1995-09-01

Stent implantation is a conservative alternative to open operation for treating benign tracheobronchial strictures. Most of the presently available stents were primarily designed for endovascular use. Their respiratory use entails a risk of iatrogenic complications. From a scientific and from an ethical point of view these risks justify preclinical evaluation of new respiratory stents in experimental models of central airway stenoses. Therefore, an attempt was made to develop such models in piglets and adult minipigs. Tracheal stenoses were obtained by creating first a segmental tracheomalacia through extramucosal resection of cartilaginous arches. The fibrous component of the stenoses was then obtained through bronchoscopic application of a caustic agent causing progressive deep mucosal and submucosal injury. Stenoses of the main bronchi were created by topical application of the caustic agent only. These models demonstrated the typical features of benign fibromalacic tracheobronchial stenoses with constant recurrence after mechanical dilation. Preliminary experiments showed that short-term problems of tolerance of stent prototypes are easily demonstrable in these models. These experimental models, which simulate quite realistically human diseases, offer the opportunity to perfect new tracheobronchial stents specifically designed for respiratory use and to evaluate their long-term tolerance before their use in humans.

Magnetoelastic galfenol as a stent material for wirelessly controlled degradation rates.

PubMed

DeRouin, Andrew; Guillory, Roger; He, Weilue; Frost, Megan; Goldman, Jeremy; Ong, Keat Ghee

2018-03-23

The gold standard of care for coronary artery disease, a leading cause of death for in the world, is balloon angioplasty in conjunction with stent deployment. However, implantation injuries and long-term presence of foreign material often promotes significant luminal tissue growth, leading to a narrowing of the artery and severely restricted blood flow. A promising method to mitigate this process is the use of biodegradable metallic stents, but thus far they have either degraded too slowly (iron) or disappeared prematurely (magnesium). The present work investigates the use of a unique type of magnetic material, galfenol (iron-gallium), for postoperative wireless control of stent degradation rates. Due to its magnetoelastic property, galfenol experiences longitudinal micron-level elongations when exposed to applied magnetic fields, allowing generation of a microstirring effect that affect its degradation behavior. In vitro indirect cytotoxicity tests on primary rat aortic smooth muscle cells indicated that galfenol byproducts must be concentrated approximately seven times from collected 60 day degradation medium to cause ∼15% of death from all cells. Surface and cross-sectional characterization of the material indicate that galfenol (Fe 80 Ga 20 ) degradation rates (∼0.55% per month) are insufficient for stenting applications. While this material may not be ideal for comprising the entire stent, there is potential for use in combination with other materials. Furthermore, the ability to control degradation rates postimplantation opens new possibilities for biodegradable stents; additional magnetoelastic materials should be investigated for use in stenting applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc.

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

PubMed

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.

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

PubMed

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.

Stent-protected carotid angioplasty using a membrane stent: a comparative cadaver study.

PubMed

Müller-Hülsbeck, Stefan; Gühne, Albrecht; Tsokos, Michael; Hüsler, Erhard J; Schaffner, Silvio R; Paulsen, Friedrich; Hedderich, Jürgen; Heller, Martin; Jahnke, Thomas

2006-01-01

To evaluate the performance of a prototype membrane stent, MembraX, in the prevention of acute and late embolization and to quantify particle embolization during carotid stent placement in human carotid explants in a proof of concept study. Thirty human carotid cadaveric explants (mild stenoses 0-29%, n = 23; moderate stenoses 30-69%, n = 3; severe stenoses 70-99%, n = 2) that included the common, internal and external carotid arteries were integrated into a pulsatile-flow model. Three groups were formed according to the age of the donors (mean 58.8 years; sample SD 15.99 years) and randomized to three test groups: (I) MembraX, n = 9; (II) Xpert bare stent, n = 10; (III) Xpert bare stent with Emboshield protection device, n = 9. Emboli liberated during stent deployment (step A), post-dilatation (step B), and late embolization (step C) were measured in 100 microm effluent filters. When the Emboshield was used, embolus penetration was measured during placement (step D) and retrieval (step E). Late embolization was simulated by compressing the area of the stented vessel five times. Absolute numbers of particles (median; >100 microm) caught in the effluent filter were: (I) MembraX: A = 7, B = 9, C = 3; (II) bare stent: A = 6.5, B = 6, C = 4.5; (III) bare stent and Emboshield: A = 7, B = 7, C.=.5, D = 8, E = 10. The data showed no statistical differences according to whether embolic load was analyzed by weight or mean particle size. When summing all procedural steps, the Emboshield caused the greatest load by weight (p = 0.011) and the largest number (p = 0.054) of particles. On the basis of these limited data neither a membrane stent nor a protection device showed significant advantages during ex vivo carotid angioplasty. However, the membrane stent seems to have the potential for reducing the emboli responsible for supposed late embolization, whereas more emboli were observed when using a protection device. Further studies are necessary and warranted.

Stent-Protected Carotid Angioplasty Using a Membrane Stent: A Comparative Cadaver Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mueller-Huelsbeck, Stefan, E-mail: muehue@rad.uni-kiel.de; Guehne, Albrecht; Tsokos, Michael

2006-08-15

Purpose. To evaluate the performance of a prototype membrane stent, MembraX, in the prevention of acute and late embolization and to quantify particle embolization during carotid stent placement in human carotid explants in a proof of concept study. Methods. Thirty human carotid cadaveric explants (mild stenoses 0-29%, n = 23; moderate stenoses 30-69%, n = 3; severe stenoses 70-99%, n = 2) that included the common, internal and external carotid arteries were integrated into a pulsatile-flow model. Three groups were formed according to the age of the donors (mean 58.8 years; sample SD 15.99 years) and randomized to three testmore » groups: (I) MembraX, n 9; (II) Xpert bare stent, n = 10; (III) Xpert bare stent with Emboshield protection device, n = 9. Emboli liberated during stent deployment (step A), post-dilatation (step B), and late embolization (step C) were measured in 100 {mu}m effluent filters. When the Emboshield was used, embolus penetration was measured during placement (step D) and retrieval (step E). Late embolization was simulated by compressing the area of the stented vessel five times. Results. Absolute numbers of particles (median; >100 {mu}m) caught in the effluent filter were: (I) MembraX: A = 7, B = 9, C = 3; (II) bare stent: A 6.5, B = 6, C = 4.5; (III) bare stent and Emboshield: A = 7, B = 7, C.=.5, D = 8, E = 10. The data showed no statistical differences according to whether embolic load was analyzed by weight or mean particle size. When summing all procedural steps, the Emboshield caused the greatest load by weight (p 0.011) and the largest number (p = 0.054) of particles. Conclusions. On the basis of these limited data neither a membrane stent nor a protection device showed significant advantages during ex vivo carotid angioplasty. However, the membrane stent seems to have the potential for reducing the emboli responsible for supposed late embolization, whereas more emboli were observed when using a protection device. Further studies are

Functional Nanoarchitectures For Enhanced Drug Eluting Stents

NASA Astrophysics Data System (ADS)

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.

Nitinol stents in the treatment of benign proximal tracheal stenosis or tracheomalacia.

PubMed

Isa, A Y; Macandie, C; Irvine, B W

2006-01-01

Nitinol stents have been used in the treatment of benign tracheal stenosis. A retrospective review of five patients treated at Stobhill Hospital over the last six and a half years is presented. Age at presentation ranged from 17 to 76 years. The minimum follow-up period was 23 months and the maximum was 78 months. All our patients were successfully decannulated, with none requiring recannulation. Four patients developed granulation tissue related to the stent at intervals ranging from three weeks to 41 months post stenting. Topical mitomycin C application has been useful after resection of granulations using the carbon dioxide (CO2) laser. Stent migration occurred in one patient three weeks after insertion. Nitinol stents are easy to insert and effective in the treatment of tracheal stenosis, but can have associated morbidity. Their use should be considered carefully, as insertion should be regarded as permanent. Publications reporting experience and outcome with the use of Nitinol stents in the trachea are reviewed.

Fourth update on CT angiography of coronary stents: in vitro evaluation of 24 novel stent types.

PubMed

Hickethier, Tilman; Wenning, Justus; Doerner, Jonas; Maintz, David; Michels, Guido; Bunck, Alexander C

2017-01-01

Background Non-invasive evaluation of coronary stent patency by coronary computed tomography angiography (cCTA) remains challenging. Multiple studies showed that CT technology but also individual stent design strongly influence the assessability of coronary stents by cCTA. Purpose To expand the available data on cCTA characteristics of coronary stents by 24 novel types to help interpreting examinations of patients after stent placement and selecting which stents are suitable for assessment by cCTA. Material and Methods Twenty-four novel coronary stents (17 cobalt-chromium, six stainless-steel, one platinum-chromium) were examined in a coronary phantom. Standard cCTA parameters with stent-specific algorithms were used. Image quality was quantified for each stent using established parameters (in-stent attenuation alteration and visible lumen diameter). Results Most stents (n = 14) showed lumen visibilities of 45-55%. No severe restriction of lumen visibility (>60%) was found. The majority of stents (n = 13) caused only small intraluminal attenuation deviations and no severe alterations (>20%) were found. When grouped by manufacturing material, no significant differences were found between cobalt-chromium and stainless-steel with identical mean visible diameters (1.52 ± 0.17 mm vs. 1.52 ± 0.13 mm) and comparable attenuation alterations (35.04 ± 16.56 HU vs. 21.25 ± 14.60 HU). The only platinum-chromium stent showed a smaller visible diameter (1.23 mm) and higher attenuation alteration (41.70 HU), but was also deemed to be assessable by cCTA. Conclusion All 24 novel evaluated stents are eligible for non-invasive evaluation by cCTA without significant differences between cobalt-chromium and stainless-steel stents. This updated catalogue of CT appearances of current coronary stents may serve as reference when taking care of patients with stents in need of coronary imaging.

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

PubMed

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.

Double Y-stenting for tracheobronchial stenosis.

PubMed

Oki, Masahide; Saka, Hideo

2012-12-01

The purpose of the present study was to evaluate the feasibility, efficacy and safety of the double Y-stenting technique, by which silicone Y-stents are placed on both the main carina and another peripheral carina, for patients with tracheobronchial stenosis. Under general anaesthesia, using rigid and flexible bronchoscopes, a Dumon™ Y-stent (Novatech, La Ciotat, France) was first placed on the primary right or secondary left carina followed by another Y-stent on the main carina so as to insert the bronchial limb of the stent into the first Y-stent. Patients who underwent double Y-stent placement during 3 yrs and 1 month in a single centre were retrospectively reviewed. In the study period, 93 patients underwent silicone stent placement and 12 (13%) underwent double Y-stent placement (11 for right and one for left bronchus). A combination of Y-stents, 14 × 10 × 10 mm and 16 × 13 × 13 mm in outer diameter, were most frequently used. Dyspnoea was relieved in all patients. Six out of seven patients with supplemental oxygen before stent placement could be discharged without supplemental oxygen. Median survival after stenting was 94.5 days. One pneumothorax and one granuloma formation occurred. Double Y-stent placement for patients with tracheobronchial stenosis was technically feasible, effective and acceptably safe.

Learning from the Cardiologists and Developing Eluting Stents Targeting the Mtor Pathway for Pulmonary Application; A Future Concept for Tracheal Stenosis

PubMed Central

Zarogoulidis, Paul; Darwiche, Kaid; Tsakiridis, Kosmas; Teschler, Helmut; Yarmus, Lonny; Zarogoulidis, Konstantinos; Freitag, Lutz

2014-01-01

Tracheal stenosis due to either benign or malignant disease is a situation that the pulmonary physicians and thoracic surgeons have to cope in their everyday clinical practice. In the case where tracheal stenosis is caused due to malignancy mini-interventional interventions with laser, apc, cryoprobe, balloon dilation or with combination of more than one equipment and technique can be used. On the other hand, in the case of a benign disease such as; tracheomalacia the clinician can immediately upon diagnosis proceed to the stent placement. In both situations however; it has been observed that the stents induce formation of granuloma tissue in both or one end of the stent. Therefore a frequent evaluation of the patient is necessary, taking also into account the nature of the primary disease. Evaluation methodologies identifying different types and extent of the trachea stenosis have been previously published. However; we still do not have an effective adjuvant therapy to prevent granuloma tissue formation or prolong already treated granuloma lesions. There have been proposed many mechanisms which induce the abnormal growth of the local tissue, such as; local pressure, local stress, inflammation and vascular endothelial growth factor overexpression. Immunomodulatory agents inhibiting the mTOR pathway are capable of inhibiting the inflammatory cascade locally. In the current mini-review we will try to present the current knowledge of drug eluting stents inhibiting the mTOR pathway and propose a future application of these stents as a local anti-proliferative treatment. PMID:24454525

Learning from the Cardiologists and Developing Eluting Stents Targeting the Mtor Pathway for Pulmonary Application; A Future Concept for Tracheal Stenosis.

PubMed

Zarogoulidis, Paul; Darwiche, Kaid; Tsakiridis, Kosmas; Teschler, Helmut; Yarmus, Lonny; Zarogoulidis, Konstantinos; Freitag, Lutz

2013-08-26

Tracheal stenosis due to either benign or malignant disease is a situation that the pulmonary physicians and thoracic surgeons have to cope in their everyday clinical practice. In the case where tracheal stenosis is caused due to malignancy mini-interventional interventions with laser, apc, cryoprobe, balloon dilation or with combination of more than one equipment and technique can be used. On the other hand, in the case of a benign disease such as; tracheomalacia the clinician can immediately upon diagnosis proceed to the stent placement. In both situations however; it has been observed that the stents induce formation of granuloma tissue in both or one end of the stent. Therefore a frequent evaluation of the patient is necessary, taking also into account the nature of the primary disease. Evaluation methodologies identifying different types and extent of the trachea stenosis have been previously published. However; we still do not have an effective adjuvant therapy to prevent granuloma tissue formation or prolong already treated granuloma lesions. There have been proposed many mechanisms which induce the abnormal growth of the local tissue, such as; local pressure, local stress, inflammation and vascular endothelial growth factor overexpression. Immunomodulatory agents inhibiting the mTOR pathway are capable of inhibiting the inflammatory cascade locally. In the current mini-review we will try to present the current knowledge of drug eluting stents inhibiting the mTOR pathway and propose a future application of these stents as a local anti-proliferative treatment.

Endoscopic management of malignant biliary obstruction by means of covered metallic stents: primary stent placement vs. re-intervention.

PubMed

Kida, M; Miyazawa, S; Iwai, T; Ikeda, H; Takezawa, M; Kikuchi, H; Watanabe, M; Imaizumi, H; Koizumi, W

2011-12-01

Recent progress in chemotherapy has prolonged the survival of patients with malignant biliary strictures, leading to increased rates of stent occlusion. Occlusion of covered metallic stents now occurs in about half of all patients with malignant biliary strictures. The removal of metallic stents followed by placement of a second stent has been attempted, but outcomes remain controversial. The aim of the current study was to evaluate the effectiveness and safety of the primary placement and secondary placement (re-intervention) of covered metallic stents and to assess the feasibility and safety of stent removal. The study included 186 patients with unresectable malignant biliary strictures who underwent primary stent placement between October 2001 and March 2010.  Covered biliary self-expandable metal stents (SEMSs) were removed in 39 of these patients, and 36 underwent re-intervention. The patency times, occlusion rates of the first stent and re-intervention, success rates of stent removal, and complications were investigated. Covered SEMSs were placed in 186 patients. The median patency time of the first stent was 352 days. Stent occlusion occurred in 48.9 % of the patients and was mainly caused by debris or food residue (37 %), dislocation (19 %), and migration with hyperplasia (19 %). Stent removal was attempted in 50 patients and was successful without complication in 39 (78 %). Most of the patients in whom stent removal was unsuccessful had migration with hyperplasia. The median patency time of the second stent was 263 days. The stent patency time did not significantly differ between the first and the second stent. Covered SEMSs could be safely removed at the time of stent occlusion. Patency rates were similar for initial stent placement and re-intervention. © Georg Thieme Verlag KG Stuttgart · New York.

The applicability of using straight ureteral stents for the treatment of ureteral stones in presumably non-compliant patients.

PubMed

Mydlo, J H; Streater, S

2001-01-01

There have been many reports describing the complications of retained ureteral stents following stone treatment. We wanted to evaluate the practicality of definitive treatment of poorly compliant patients who present with ureteral stones using a straight stent connected to a urethral catheter alone and compared these to patients treated with double-J stents alone. We treated 23 patients (12 in group I and 11 patients in group II) who had a ureteral stone of 6 mm or less, with an indwelling straight stent and a double-J stent, respectively, while on oral antibiotics. We followed these patients 1 week later with an abdominal X-ray prior to removing the stent. Eleven patients in group I and 9 patients in group II passed their stones spontaneously. Three patients required surgical intervention with a ureterscope and laser lithotripsy. There were no cases of infection or pyelonephritis. Although each of the straight-stent-treated patients returned to our clinic for follow-up, only 5 of the 11 double-J stent patients returned for follow-up. The remaining 6 patients had to be contacted to remind them that they still had an internal stent. Although technologic advances now allow many urologists to definitively treat ureteral stones, some urologists may lack the proper equipment and/or assistance to treat the stone at the time of presentation, or may deal with non-compliant patients. Therefore, in these certain circumstances, treatment of small ureteral stones in non-compliant patients using a straight stent connected to a leg bag, as either definitive or initial treatment, may be of practical use and avoid the risk of retained double-J ureteral stents. Copyright 2001 S. Karger AG, Basel

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

PubMed Central

Guan, Ying; Wang, Lu; Lin, Jing; King, Martin W.

2016-01-01

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. PMID:28773781

Mechanical properties of different airway stents.

PubMed

Ratnovsky, Anat; Regev, Noa; Wald, Shaily; Kramer, Mordechai; Naftali, Sara

2015-04-01

Airway stents improve pulmonary function and quality of life in patients suffering from airway obstruction. The aim of this study was to compare main types of stents (silicone, balloon-dilated metal, self-expanding metal, and covered self-expanding metal) in terms of their mechanical properties and the radial forces they exert on the trachea. Mechanical measurements were carried out using a force gauge and specially designed adaptors fabricated in our lab. Numerical simulations were performed for eight different stent geometries, inserted into trachea models. The results show a clear correlation between stent diameter (oversizing) and the levels of stress it exerts on the trachea. Compared with uncovered metal stents, metal stents that are covered with less stiff material exert significantly less stress on the trachea while still maintaining strong contact with it. The use of such stents may reduce formation of mucosa necrosis and fistulas while still preventing stent migration. Silicone stents produce the lowest levels of stress, which may be due to weak contact between the stent and the trachea and can explain their propensity for migration. Unexpectedly, stents made of the same materials exerted different stresses due to differences in their structure. Stenosis significantly increases stress levels in all stents. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

[Stents in iliac vascular changes].

PubMed

Gross-Fengels, W; Friedmann, G; Fischbach, R; Erasmi, H; Bulling, B

1991-01-01

The results of 79 iliac stent placements in 64 patients are reported. The technical success rate was 96%. The systolic pressure gradient dropped from 44 mmHg before to 2.8 mmHg after stent placement. This differed significantly as compared to a group treated by conventional PTA (gradient 5.8 mmHg). The cumulative patency after 18-20 months was 90%. Angiographic controls up to 19 months after "stenting" demonstrated only one secondary stent occlusion. Iliac stents therefore are a very valuable supplement to classic PTA.

Biodegradable metals for cardiovascular stents: from clinical concerns to recent Zn - alloys

PubMed Central

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

2016-01-01

Metallic stents are commonly used to promote revascularization and maintain patency of plaqued or damaged arteries following balloon angioplasty. To mitigate the long-term side effects associated with corrosion-resistant stents (i.e. chronic inflammation and late stage thrombosis), a new generation of so-called “bioabsorbable” stents is currently being developed. The bioabsorbable coronary stents will corrode and be absorbed by the artery after completing their task as vascular scaffolding. Research spanning the last two decades has focused on biodegradable polymeric, iron-based, and magnesium-based stent materials. The inherent mechanical and surface properties of metals make them more attractive stent material candidates than their polymeric counterparts. Unfortunately, iron produces a voluminous, retained oxide product in the arterial wall, whereas magnesium and its alloys corrode too rapidly. A third class of metallic bioabsorbable materials that are based on zinc has been introduced in the last few years. As summarized in this contribution, this new zinc-based class of materials demonstrates the potential for an absorbable metallic stent with the mechanical and biodegradation characteristics required for optimal stent performance. They appear to be free of flaws that limit the application of iron- and magnesium-based alloys, and polymers. This review compares bioabsorbable materials and summarizes progress towards bioabsorbable stents. It emphasizes on current understanding of physiological and biological benefits of zinc and its biocompatibility. Finally, the review provides an outlook on challenges in designing zinc-based stents of optimal mechanical properties and biodegradation rate. PMID:27094868

Evaluation of balloon withdrawal forces with bare-metal stents, compared with Taxus and Cypher drug-eluting coronary stents: balloon, stent and polymer interactions.

PubMed

Turk, Marvee; Gupta, Vishal; Fischell, Tim A

2010-03-01

There have been reports of serious complications related to difficulty removing the deflated Taxus stent delivery balloon after stent deployment. The purpose of this study was to determine whether the Taxus SIBS polymer was "sticky" and associated with an increase in the force required to remove the stent delivery balloon after stent deployment, using a quantitative, ex-vivo model. Balloon-polymer-stent interactions during balloon withdrawal were measured with the Taxus Liberté, Liberté bare-metal stent (BMS; no polymer = control), the Cordis Cypher drug-eluting stent (DES; PEVA/PBMA polymer) and the BX Velocity (no polymer). We quantitatively measured the force required to remove the deflated stent delivery balloon from each of these stents in simulated vessels at 37 degrees C in a water bath. Balloon withdrawal forces were measured in straight (0 degree curve), mildly curved (20 degree curve) and moderately curved (40 degree curve) simulated vessel segments. The average peak force required to remove the deflated balloon catheter from the Taxus Liberté DES, the Liberté BMS, the Cypher DES, and the Bx Velocity BMS were similar in straight segments, but were much greater for the Taxus Liberté in the moderately curved segments (1.4 lbs vs. 0.11 lbs, 0.11 lbs and 0.12 lbs, respectively; p < 0.0001). The SIBS polymer of the Taxus Liberté DES appears to be "sticky" and is associated with high forces required to withdraw the deflated balloon from the deployed stent in curved segments. This withdrawal issue may help to explain the clinical complications that have been reported with this device.

Computational fluid dynamics analysis of balloon-expandable coronary stents: influence of stent and vessel deformation.

PubMed

Martin, David M; Murphy, Eoin A; Boyle, Fergal J

2014-08-01

In many computational fluid dynamics (CFD) studies of stented vessel haemodynamics, the geometry of the stented vessel is described using non-deformed (NDF) geometrical models. These NDF models neglect complex physical features, such as stent and vessel deformation, which may have a major impact on the haemodynamic environment in stented coronary arteries. In this study, CFD analyses were carried out to simulate pulsatile flow conditions in both NDF and realistically-deformed (RDF) models of three stented coronary arteries. While the NDF models were completely idealised, the RDF models were obtained from nonlinear structural analyses and accounted for both stent and vessel deformation. Following the completion of the CFD analyses, major differences were observed in the time-averaged wall shear stress (TAWSS), time-averaged wall shear stress gradient (TAWSSG) and oscillatory shear index (OSI) distributions predicted on the luminal surface of the artery for the NDF and RDF models. Specifically, the inclusion of stent and vessel deformation in the CFD analyses resulted in a 32%, 30% and 31% increase in the area-weighted mean TAWSS, a 3%, 7% and 16% increase in the area-weighted mean TAWSSG and a 21%, 13% and 21% decrease in the area-weighted mean OSI for Stents A, B and C, respectively. These results suggest that stent and vessel deformation are likely to have a major impact on the haemodynamic environment in stented coronary arteries. In light of this observation, it is recommended that these features are considered in future CFD studies of stented vessel haemodynamics. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

Proximal protection with hybrid stent, a safer combination for carotid artery stenting against carotid endarterectomy?

PubMed

Gürkaş, E; Ak, F; Orhan, G; Bozkurt, E; Ulusoy, E K

2015-12-01

Carotid revascularization is an established theurapeutic modality in preventing stroke and death among patients with severe carotid stenosis. Although carotid endarterectomy remains as the primary option, carotid stenting is accepted as an alternative for patients with high risk for carotid endarterectomy. Recently published reports have better results with proximal protection devices when compared with distal protection devices. These studies have revealed less microembolic signals and less periprocedural new ischemic lesions on diffusion weighted magnetic resonance imaging. Stent choice may be also important for these procedures as open cell stent design has advantage of better flexibility whereas closed cell systems have an advantage of better scaffolding. Hybrid stents which are composed of open cells in the proximal and distal part and closed cells in the middle may carry both advantages. The aim of this study is to demonstrate whether combination of proximal protection devices with hybrid stents can be a safe alternative for carotid stenting in terms of periprocedural and 30-day outcomes. Here we retrospectively evaluated 68 symptomatic carotid stenosis patients undergoing carotid stenting with hybrid stent (Cristallo Ideale®, Invatec s.r.l., Medtronic, Italy) and proximal protection device (MO.MA®, Invatec s.r.l., Medtronic, Italy). Our results showed only 1 minor stroke in the periprocedural period and during the first 30-day after stenting, with no death or myocardial infarction. Although our case number is not large, we propose that carotid stenting may be safer with utilization of proximal protection system and hybrid type carotid stents.

Ureteral Stents. New Materials and Designs

NASA Astrophysics Data System (ADS)

Monga, Manoj

2008-09-01

Issues of stent migration and challenges of stent placement can be addressed adequately with current stent designs and materials, and an emphasis on precision in technique. Future changes in ureteral stents will need to maintain the current standard that has been set with existing devices in these regards. In contrast, new advances are sorely needed in encrustation and infection associated with ureteral stents. The main target for future development in ureteral stent materials lies in a biodegradable stent that degrades either on demand or degrades reliably within one-month with predictable degradation patterns that do not predispose to urinary obstruction, discomfort or need for secondary procedures. The main target for future development in ureteral stent design is improved patient comfort.

Automated measurement of stent strut coverage in intravascular optical coherence tomography

NASA Astrophysics Data System (ADS)

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.

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.

PubMed

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.

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

PubMed

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.

A novel balloon assisted two-stents telescoping technique for repositioning an embolized stent in the pulmonary conduit.

PubMed

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.

Composite self-expanding bioresorbable prototype stents with reinforced compression performance for congenital heart disease application: Computational and experimental investigation.

PubMed

Zhao, Fan; Xue, Wen; Wang, Fujun; Liu, Laijun; Shi, Haoqin; Wang, Lu

2018-08-01

Stents are vital devices to treat vascular stenosis in pediatric patients with congenital heart disease. Bioresorbable stents (BRSs) have been applied to reduce challenging complications caused by permanent metal stents. However, it remains almost a total lack of BRSs with satisfactory compression performance specifically for children with congenital heart disease, leading to importantly suboptimal effects. In this work, composite bioresorbable prototype stents with superior compression resistance were designed by braiding and annealing technology, incorporating poly (p-dioxanone) (PPDO) monofilaments and polycaprolactone (PCL) multifilament. Stent prototype compression properties were investigated. The results revealed that novel composite prototype stents showed superior compression force compared to the control ones, as well as recovery ability. Furthermore, deformation mechanisms were analyzed by computational simulation, which revealed bonded interlacing points among yarns play an important role. This research presents important clinical implications in bioresorbable stent manufacture and provides further study with an innovative stent design. Copyright © 2018 Elsevier Ltd. All rights reserved.

Frequency of occurrence of urinary tract infection in double j stented versus non-stented renal transplant recipients.

PubMed

Shohab, Durre; Khawaja, Athar; Atif, Emad; Jamil, Imran; Ali, Iftikhar; Akhter, Saeed

2015-01-01

Prophylactic ureteric stenting in renal transplant recipients prevents major surgical complications such as ureteric leak and obstruction on the one hand while, on the other hand, it is associated with complications like urinary tract infections (UTI), hematuria, stent migration, stent encrustation and forgotten stents. UTI is documented to be most common complication associated with double J (DJ) stent. In this retrospective observational study involving 157 patients, we compared the frequency of occurrence of UTI in DJ-stented versus non-stented renal transplant recipients. The study patients had undergone renal transplantation, with or without DJ-stenting, between January 2007 and June 2012. The mean age of the study subjects was 34.01 ± 14.63 years. The patients were followed-up for one year post-transplantation with regular evaluation, including detailed assessment, complete blood picture, renal function tests, routine urine examination and cultures. Data were collected through chart and electronic record review. Of a total of 157 patients, 61 (38.85%) developed UTI, including 30 of 74 stented patients (40.54%) and 31 of 83 non-stented renal transplant recipients (37.34%). Relative risk was calculated to be 1.08. The mean serum creatinine at the end of one year was 1.47 mg/dL in DJ-stented patients and 1.36 mg/dL in nonstented patients. Our study suggests that there is no significant difference in the frequency of UTI between DJ-stented and non-stented renal transplant recipients.

Everolimus-eluting stents in interventional cardiology

PubMed Central

Townsend, Jacob C; Rideout, Phillip; Steinberg, Daniel H

2012-01-01

Bare metal stents have a proven safety record, but limited long-term efficacy due to in-stent restenosis. First-generation drug-eluting stents successfully countered the restenosis rate, but were hampered by concerns about their long-term safety. Second generation drug-eluting stents have combined the low restenosis rate of the first generation with improved long-term safety. We review the evolution of drug-eluting stents with a focus on the safety, efficacy, and unique characteristics of everolimus-eluting stents. PMID:22910420

Biodegradable-polymer drug-eluting stents vs. bare metal stents vs. durable-polymer drug-eluting stents: a systematic review and Bayesian approach network meta-analysis.

PubMed

Kang, Si-Hyuck; Park, Kyung Woo; Kang, Do-Yoon; Lim, Woo-Hyun; Park, Kyung Taek; Han, Jung-Kyu; Kang, Hyun-Jae; Koo, Bon-Kwon; Oh, Byung-Hee; Park, Young-Bae; Kandzari, David E; Cohen, David J; Hwang, Seung-Sik; Kim, Hyo-Soo

2014-05-01

The aim of this study was to compare the safety and efficacy of biodegradable-polymer (BP) drug-eluting stents (DES), bare metal stents (BMS), and durable-polymer DES in patients undergoing coronary revascularization, we performed a systematic review and network meta-analysis using a Bayesian framework. Study stents included BMS, paclitaxel-eluting (PES), sirolimus-eluting (SES), endeavor zotarolimus-eluting (ZES-E), cobalt-chromium everolimus-eluting (CoCr-EES), platinium-chromium everolimus-eluting (PtCr-EES), resolute zotarolimus-eluting (ZES-R), and BP biolimus-eluting stents (BP-BES). After a systematic electronic search, 113 trials with 90 584 patients were selected. The principal endpoint was definite or probable stent thrombosis (ST) defined according to the Academic Research Consortium within 1 year. Biodegradable polymer-biolimus-eluting stents [OR, 0.56; 95% credible interval (CrI), 0.33-0.90], SES (OR, 0.53; 95% CrI, 0.38-0.73), CoCr-EES (OR, 0.34; 95% CrI, 0.23-0.52), and PtCr-EES (OR, 0.31; 95% CrI, 0.10-0.90) were all superior to BMS in terms of definite or probable ST within 1 year. Cobalt-chromium everolimus-eluting stents demonstrated the lowest risk of ST of all stents at all times after stent implantation. Biodegradable polymer-biolimus-eluting stents was associated with a higher risk of definite or probable ST than CoCr-EES (OR, 1.72; 95% CrI, 1.04-2.98). All DES reduced the need for repeat revascularization, and all but PES reduced the risk of myocardial infarction compared with BMS. All DESs but PES and ZES-E were superior to BMS in terms of ST within 1 year. Cobalt-chromium everolimus-eluting stents was safer than any DES even including BP-BES. Our results suggest that not only the biodegradability of polymer, but the optimal combination of stent alloy, design, strut thickness, polymer, and drug all combined determine the safety of DES.

Comparison of intraluminal radiofrequency ablation and stents vs. stents alone in the management of malignant biliary obstruction.

PubMed

Cui, Wei; Wang, Yu; Fan, Wenzhe; Lu, Mingjian; Zhang, Yingqiang; Yao, Wang; Li, Jiaping

2017-11-01

To retrospectively evaluate the added benefit of adding intraluminal radiofrequency ablation (RFA) to biliary metal stent placement for patients with malignant biliary obstruction (MBO). From November 2013 to December 2015, 89 patients with MBO who had undergone percutaneous intraluminal RFA and stent placement (RFA-stent group, n = 50) or stent placement only (stent group, n = 39) were included. Outcomes were compared according to the type of tumour: cholangiocarcinoma or non-cholangiocarcinoma. Primary and secondary stent patency (PSP, SSP) were significantly higher for the RFA-stent group than the stent group (PSP: 7.0 months vs. 5.0 months, p = 0.006; SSP: 10.0 months vs. 5.6 months, p < 0.001), with overall survival being comparable (5.0 months vs. 4.7 months, p = 0.068). In subgroup analysis, RFA-stent showed significant PSP benefits compared to stent alone in patients with cholangiocarcinoma (7.4 months vs. 4.3 months; p = 0.009), but with comparable outcomes in patients with non-cholangiocarcinoma (6.3 months vs. 5.2 months; p = 0.266). The SSP was improved in both subgroups (cholangiocarcinoma, 12.6 months vs. 5.0 months, p < 0.001; non-cholangiocarcinoma, 10.3 months vs. 5.5 months, p = 0.013). Technical success and clinical success were not significantly different between the two groups. The rate of complication was higher for the RFA-stent group, but tolerable when compared to the stent group. Although survival was comparable between the groups, RFA-stent confers therapeutic benefits to patients with MBO in terms of stent patency compared to stent placement alone, especially in those with cholangiocarcinoma.

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

PubMed

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.

Stent Design Affects Femoropopliteal Artery Deformation.

PubMed

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.

Long-term outcomes and risk factors of biliary stent dysfunction after endoscopic double stenting for malignant biliary and duodenal obstructions.

PubMed

Matsumoto, Kazuyuki; Kato, Hironari; Tsutsumi, Koichiro; Mizukawa, Sho; Yabe, Syuntaro; Seki, Hiroyuki; Akimoto, Yutaka; Uchida, Daisuke; Tomoda, Takeshi; Yamamoto, Naoki; Horiguchi, Shigeru; Kuwaki, Kenji; Okada, Hiroyuki

2017-07-01

Few reports describe the endoscopic double-stenting procedure for malignant biliary and duodenal obstructions. We evaluated the clinical outcomes from double stenting, and analyzed the risk factors for biliary stent dysfunction following double stenting. Eighty-one patients who underwent endoscopic double stenting for malignant biliary and duodenal obstructions were retrospectively analyzed. We determined the stent dysfunction rate and the biliary stent dysfunction risk factors, and analyzed the endoscopic reintervention results. Overall survival time and survival time following double stenting were 365 (38-1673) days and 73 (20-954) days, respectively. After double stenting, the 3-month and 6-month duodenal stent dysfunction rates were 14% and 41%, respectively. Reintervention technical success rate was 100% (10/10), and mean gastric outlet obstruction scoring system scores improved from 0.7 to 2.4 points (P < 0.001). The 3-month and 6-month biliary stent dysfunction rates were 26% and 41%, respectively. The reintervention technical and clinical success rates were 95% (20/21) and 81% (17/21), respectively. Risk factors for biliary stent dysfunction following double stenting were events associated with duodenal stent dysfunction (odds ratio [OR], 11.1; 95% confidence interval [CI], 2.09-87.4; P = 0.0044) and the biliary stent end's location (OR, 6.93; 95% CI, 1.37-40.2; P = 0.0019). Some patients had stent dysfunction irrespective of the survival period after double stenting. Endoscopic reintervention was technically feasible and clinically effective even after double stenting. Duodenal stent dysfunction and biliary stent end's location were risk factors for biliary stent dysfunction. © 2017 Japan Gastroenterological Endoscopy Society.

Validation of an image registration and segmentation method to measure stent graft motion on ECG-gated CT using a physical dynamic stent graft model

NASA Astrophysics Data System (ADS)

Koenrades, Maaike A.; Struijs, Ella M.; Klein, Almar; Kuipers, Henny; Geelkerken, Robert H.; Slump, Cornelis H.

2017-03-01

The application of endovascular aortic aneurysm repair has expanded over the last decade. However, the long-term performance of stent grafts, in particular durable fixation and sealing to the aortic wall, remains the main concern of this treatment. The sealing and fixation are challenged at every heartbeat due to downward and radial pulsatile forces. Yet knowledge on cardiac-induced dynamics of implanted stent grafts is sparse, as it is not measured in routine clinical follow-up. Such knowledge is particularly relevant to perform fatigue tests, to predict failure in the individual patient and to improve stent graft designs. Using a physical dynamic stent graft model in an anthropomorphic phantom, we have evaluated the performance of our previously proposed segmentation and registration algorithm to detect periodic motion of stent grafts on ECG-gated (3D+t) CT data. Abdominal aortic motion profiles were simulated in two series of Gaussian based patterns with different amplitudes and frequencies. Experiments were performed on a 64-slice CT scanner with a helical scan protocol and retrospective gating. Motion patterns as estimated by our algorithm were compared to motion patterns obtained from optical camera recordings of the physical stent graft model in motion. Absolute errors of the patterns' amplitude were smaller than 0.28 mm. Even the motion pattern with an amplitude of 0.23 mm was measured, although the amplitude of motion was overestimated by the algorithm with 43%. We conclude that the algorithm performs well for measurement of stent graft motion in the mm and sub-mm range. This ultimately is expected to aid in patient-specific risk assessment and improving stent graft designs.

Comparison of Flow Characteristics of Novel Three-Dimensional Printed Ureteral Stents Versus Standard Ureteral Stents in a Porcine Model.

PubMed

Del Junco, Michael; Yoon, Renai; Okhunov, Zhamshid; Abedi, Garen; Hwang, Christina; Dolan, Benjamin; Landman, Jaime

2015-09-01

We compared the flow characteristics of novel three-dimensional (3D) printed ureteral stents with four conventional double-pigtail stents in an ex vivo porcine model. In six ex vivo porcine urinary systems with kidneys and ureters intact, we deployed a 5F occlusion catheter in an interpolar calix. We tested each system with antegrade irrigation with a 0.9% saline bag placed 35 cm above the renal pelvis. We evaluated four standard stents (6F Universa® Soft, 7F Percuflex,™ 7/10F Applied Endopyelotomy, 8.5F Filiform Double Pigtail) and compared them with a 9F 3D printed prototype stent. For each stent, we measured the total, extraluminal, and intraluminal flow rates. The mean total flow rates for 3D printed stents were significantly higher than the 6F, 7F, and 7/10F stents (P<0.05). No significant difference was seen in the total flow rate for the 3D printed stent and the 8.5F stent. The mean extraluminal flow rates for the 3D stents were similar to those of 7F stents, but significantly lower than 6F stents (P<0.001) and 8.5F stents (P<0.05) and higher than 7/10F stents (P<0.001). The mean intraluminal flow rates for the 3D printed stents were significantly higher than the 6F, 7F, 7/10F, and 8.5F stents (P<0.05). In this pilot study, 3D printed stents manifested a mean total flow rate comparable to the flow rates of contemporary stents. Continued advances in technology and material may permit functionally feasible 3D printed ureteral stents.

Current Status of Biliary Metal Stents

PubMed Central

Nam, Hyeong Seok; Kang, Dae Hwan

2016-01-01

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

Stenting versus non-stenting following uncomplicated ureteroscopic lithotripsy: Comparsion and evaluation of symptoms.

PubMed

Savić, Slaviša; Vukotić, Vinka; Lazić, Miodrag; Savić, Nataša

2016-09-01

Currently, ureterorenoscopic (URS) stone fragmentation and removal is the treatment of choice for managing ureteral stones, especially mid and distal ones and is advocated as initial management of ureteric stones. The aim of this work was to evaluate the symptoms, necessity, potential benefits and adverse effects of ureteral stent placement after uncomplicated ureteroscopic lithotripsy. This retrospective-prospective study evaluated a total of 125 patients who had underwent ureteroscopic lithotripsy (URSL). The patients were divided into two groups: stented (59 patients) and unstented (controls, 66 patients). The outcomes measured and compared between the two groups included: stone free rate, postoperative patient pain validated by scale, lower urinary tract symptoms (LUTS), the need for unplanned hospital care, stent related complications, and functional recovery in the form return to normal physical activities. A successful outcome, defined as being stonefree after 12 weeks, was achieved in all 125 (100%) patients. The stone-free rate showed no significant differences between the two groups. LUTS was frequent complaint in the stented group, with statistically significant difference in the domain of frequency/urgency (p = 0.0314). There was a statistically significant difference between the groups in the mean operative time and mean hospitalization time, mean pain visual analog scale (VAS) score and in the use of nonnarcotic analgesic. On the day of the surgery and until postoperative day 3 (POD 3) and postoperative day 5 (POD 5), the pain score was much higher among stented patients than among the controls (p = 0.0001) and non-narcotic analgesic use (p = 0.001) was frequently required in the stented group. Routine placement of ureteral stent after URSL is not mandatory and may be associated with stent side effects. Uncomplicated URSL is safe without stent placement after the treatment.

Configuration affects parallel stent grafting results.

PubMed

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

Reintervention for stent occlusion after bilateral self-expandable metallic stent placement for malignant hilar biliary obstruction.

PubMed

Inoue, Tadahisa; Naitoh, Itaru; Okumura, Fumihiro; Ozeki, Takanori; Anbe, Kaiki; Iwasaki, Hiroyasu; Nishie, Hirotada; Mizushima, Takashi; Sano, Hitoshi; Nakazawa, Takahiro; Yoneda, Masashi; Joh, Takashi

2016-11-01

Endoscopic reintervention for stent occlusions following bilateral self-expandable metallic stent (SEMS) placement for malignant hilar biliary obstruction (MHBO) is challenging, and time to recurrent biliary obstruction (RBO) of the revisionary stent remains unclear. We aimed to clarify a suitable reintervention method for stent occlusions following bilateral SEMS placement for MHBO. Between 2002 and 2014, 52 consecutive patients with MHBO who underwent endoscopic reintervention for stent occlusion after bilateral SEMS placement were enrolled at two university hospitals and one tertiary care referral center. We retrospectively evaluated the technical and functional success rates of the reinterventions, and the time to RBO of the revisionary stents. Technical and functional success rates of the reinterventions were 92% (48/52) and 90% (43/48), respectively. Univariate analysis did not determine any significant predictive factors for technical and functional failures. Median time to RBO of the revisionary stents was 68 days. Median time to RBO was significantly longer for revisionary SEMS placement than for plastic stent placement (131 days vs 47 days, respectively; log-rank test, P = 0.005). Revisionary SEMS placement was the only independent factor that was significantly associated with a longer time to RBO of the revisionary stent in the multivariate Cox proportional hazards analysis (hazard ratio 0.37; 95% confidence interval 0.14-0.95; P = 0.039). Revisionary SEMS placement is a suitable endoscopic reintervention method for stent occlusion following bilateral SEMS placement from the perspective of time to RBO of the revisionary stent. © 2016 Japan Gastroenterological Endoscopy Society.

Clinical outcomes and stent thrombosis following off-label use of drug-eluting stents.

PubMed

Win, Htut K; Caldera, Angel E; Maresh, Kelly; Lopez, John; Rihal, Charanjit S; Parikh, Manish A; Granada, Juan F; Marulkar, Sachin; Nassif, Deborah; Cohen, David J; Kleiman, Neal S

2007-05-09

Clinical trials that have excluded patients at high risk for cardiac events have led to commercial labeling approval of drug-eluting stents; nevertheless, such high-risk patients commonly undergo stent placement in clinical practice. The degree to which they experience cardiac events at a higher rate than non-high-risk patients is unclear. To assess the rates of major adverse cardiac events during the index admission and 1 year after the implantation of drug-eluting stents in patients with high-risk angiographic and clinical features. From July 2004 to September 2005, consecutive patients who underwent attempted stent placement at 42 different hospitals throughout the United States were enrolled in a prospective multicenter registry. We analyzed outcomes of 3323 patients who received at least 1 drug-eluting stent for a reason other than acute ST-segment elevation myocardial infarction. The study population was divided into 2 groups based on presence of at least 1 of 9 off-label characteristics based on the current US Food and Drug Administration-approved indications for sirolimus- and paclitaxel-eluting stents. The composite clinical outcomes of death, myocardial infarction, or target vessel revascularization during the index admission and death, myocardial infarction, or target lesion revascularization at 1 year were evaluated. Of the 3323 patients, 1817 (54.7%) had at least 1 off-label characteristic. During the index hospitalization, the composite clinical outcome occurred in 198 (10.9%) of patients in the off-label group and 76 (5.0%) of patients in the on-label group (adjusted odds ratio, 2.32; 95% confidence interval [CI], 1.75-3.07; P<.001). At 1 year, the composite clinical outcome occurred more often in the off-label group compared with the on-label group; 309 (17.5%) vs 131 (8.9%) (adjusted hazard ratio [HR], 2.16; 95% CI, 1.74-2.67; P<.001). Stent thrombosis also occurred more frequently among patients in the off-label group during the initial

Comparison of closed-cell and hybrid-cell stent designs in carotid artery stenting: clinical and procedural outcomes

PubMed Central

Tatli, Ersan; Vatan, Mehmet Bulent; Agac, Mustafa Tarik; Gunduz, Huseyin; Akdemir, Ramazan; Kilic, Harun

2017-01-01

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. PMID:28798784

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

PubMed

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.

Clinical experience in coronary stenting with the Vivant Z Stent.

PubMed

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.

Coronary In-Stent Restenosis: Assessment with Corrected Coronary Opacification Difference across Coronary Stents Measured with CT Angiography.

PubMed

Gao, Yang; Lu, Bin; Hou, Zhi Hui; Yu, Fang Fang; Yin, Wei Hua; Wang, Zhi Qiang; Wu, Yong Jian; Mu, Chao Wei; Meinel, Felix G; McQuiston, Andrew D; Schoepf, U Joseph

2015-05-01

To determine whether changes in coronary opacification normalized to the aorta (corrected coronary opacification [CCO]) across stents can help identify in-stent restenosis (ISR) severity with use of invasive coronary angiography as the standard of reference. This study was approved by the institutional review board, and the requirement to obtain informed consent was waived. The authors retrospectively analyzed 106 patients (88 men, 18 women; mean age, 59.6 years ± 10.4; age range, 36-84 years) who had previously undergone stent implantation within 3 months of coronary computed tomographic (CT) angiography. Attenuation values in the coronary lumen were measured proximal and distal to the stents and normalized to the descending aorta. The CCO difference across the stent was compared with the severity of ISR. One-way analysis of variance least significant difference was used for comparison. A total of 141 stents were assessed. Seventy-six stents were normally patent, 18 had ISR of less than 50%, 28 had ISR of 50%-99%, and 19 were fully occluded. The median CCO differences in the four groups were 0.078, 0.163, 0.346, and 0.606, respectively. There was no significant difference between stents with an ISR of at least 50% and those with total occlusion (P = .056), although the other groups had significant differences at pairwise comparison (P < .01 for all). For stents smaller than 3 mm in diameter, the median CCO differences in the four groups were 0.086, 0.136, 0.390, and 0.471, respectively. The CCO differences across normal stents and stents with ISR of less than 50% were significantly less than those across stents with an ISR of at least 50% and those with total occlusion (P < .01 for all). There were no significant differences between stents with no ISR and those with an ISR of less than 50% (P = .821) and between stents with an ISR of at least 50% and those with an ISR of 100% (P = .836). The CCO difference across coronary stents is related to ISR severity in

Comparison of Recanalization and In-Stent Stenosis Between the Low-Profile Visualized Intraluminal Support Stent and Enterprise Stent-Assisted Coiling for 254 Intracranial Aneurysms.

PubMed

Feng, Xin; Qian, Zenghui; Liu, Peng; Zhang, Baorui; Wang, Luyao; Guo, Erkang; Wen, Xiaolong; Xu, Wenjuan; Jiang, Chuhan; Wu, Zhongxue; Li, Youxiang; Liu, Aihua

2018-01-01

To compare the rates of recanalization and in-stent stenosis between the Enterprise (EP) and low-profile visualized intraluminal support (LVIS) stent deployments for intracranial aneurysms (IAs), and the factors associated therein. Between June 2014 and July 2016, 142 patients with a total of 161 IAs were treated by LVIS stent-assisted coiling and 111 patients with a total of 142 IAs were treated by EP stent-assisted coiling at our institution. Procedure-related complications, angiographic follow-up results, and clinical outcomes were analyzed statistically. The rates of initially complete and near-complete IA occlusion immediately after the procedure were similar in the LVIS and EP groups (94.3% vs. 89.9%; P = 0.275). On follow-up, complete and near-complete occlusion rates and recanalization rates were also similar in the 2 groups (96.6% vs. 92.1%; P =0.330 and 8.0% vs. 13.5%; P = 0.245, respectively). On logistic regression analysis, a higher size ratio (SR) was significantly associated with the recanalization of aneurysms in the EP group, but not in the LVIS group. The rate of moderate to severe in-stent stenosis was lower in the LVIS group (10.2%) than in the EP group (16.8%), but the difference was not statistically significant (P = 0.198). Our data show acceptable rates of complete and near-complete occlusion with both the LVIS and EP stents. LVIS stents were associated with lower rates of recanalization and in-stent stenosis, but the difference was not significant. Higher SR (≥2) was a significant predictor of recanalization in IAs treated with EP stents, but not in those treated with LVIS stents. Copyright © 2017. Published by Elsevier Inc.

Fluoroscopic Placement of Double-Pigtail Ureteral Stents

PubMed Central

Chen, Gregory L.

2001-01-01

Purpose: Double-pigtail ureteral stent is placed cystoscopically after ureteroscopy. We describe a technique for fluoroscopic placement of ureteral stents and demonstrate its use in a non-randomized prospective study. Materials and methods: Double-pigtail stents were placed either fluoroscopically or cystoscopically in 121 consecutive patients. In the fluoroscopic method, the stent was placed over a guide wire using a stent pusher without the use of cystoscopy. Conversely, stents were placed through the working channel of the cystoscope under vision. The procedure, stent length, width, type, method, ureteral dilation, and use of a retrieval string were noted. Results: A wide range of stent sizes were used. The success with fluoroscopic placement of double-pigtail ureteral stents was 100% (89 of 89 cases). No stents migrated or required replacement. Stents were placed after ureteroscopic laser lithotripsy (53/89) and ureteroscopic tumor treatment (22/89). Cystoscopic visualization was used in 32 additional procedures requiring precise control (15 ureteral strictures and nine retrograde endopyelotomy). Conclusions: The fluoroscopic placement of ureteral stents is a safe and simple technique with a very high success rate. We have used cystoscopic placement only after incisional procedures such as retrograde endopyelotomy, stricture or ureterotomy. PMID:18493562

Dynamic Y stent fractures in crescentic tracheobronchomalacia.

PubMed

Popilevsky, Frida; Al-Ajam, Mohammad R; Ly, Vanthanh; Sanchez, Lisette Delgado; Cutaia, Michael

2012-07-01

Endobronchial stents have been used occasionally to treat benign conditions such as tracheobronchomalacia (TBM). This report describes a unique case of a patient with crescentic TBM in whom Dynamic Y stent was placed on 2 separate occasions to control symptoms and resulted in identical posterior wall stent fractures within a year of stent placement, both times. A silicone Y stent was substituted for the dynamic stent, and it has been effective in controlling symptoms for 9 months without complications. A literature review of cases of fractured Dynamic Y stents is made and factors affecting the choice of stent type for crescentic TBM are explored.

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

PubMed

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.

The application of ink-jet technology for the coating and loading of drug-eluting stents.

PubMed

Tarcha, Peter J; Verlee, Donald; Hui, Ho Wah; Setesak, Jeff; Antohe, Bogdan; Radulescu, Delia; Wallace, David

2007-10-01

The combination of drugs with devices, where locally delivered drugs elute from the device, has demonstrated distinct advantages over therapies involving systemic or local drugs and devices administered separately. Drug-eluting stents are most notable. Ink jet technology offers unique advantages for the coating of very small medical devices with drugs and drug-coating combinations, especially in cases where the active pharmaceutical agent is very expensive to produce and wastage is to be minimized. For medical devices such as drug-containing stents, the advantages of ink-jet technology result from the controllable and reproducible nature of the droplets in the jet stream and the ability to direct the stream to exact locations on the device surfaces. Programmed target deliveries of 100 microg drug, a typical dose for a small stent, into cuvettes gave a standard deviation (SD) of dose of 0.6 microg. Jetting on coated, uncut stent tubes exhibited 100% capture efficiency with a 1.8 microg SD for a 137 microg dose. In preliminary studies, continuous jetting on stents can yield efficiencies up to 91% and coefficients of variation as low as 2%. These results indicate that ink-jet technology may provide significant improvement in drug loading efficiency over conventional coating methods.

A new thermal shape memory Ti-Ni alloy stent covered with silicone.

PubMed

Nakamura, T; Shimizu, Y; Ito, Y; Matsui, T; Okumura, N; Takimoto, Y; Ariyasu, T; Kiyotani, T

1992-01-01

An attempt was made to develop an airway stent for nonsurgical transluminal implantation using a bronchofiberscope. The stent is composed of a single wire with a diameter of 0.5 mm. The wire is made of thermal shape memory titanium nickel alloy, with a transition temperature of 25-30 degrees C. To avoid direct contact between the metal and the tissue, the wire is covered with a 300 microns thick coating of silicone. The stent is horseshoe shaped in cross-section. It is 15 mm in outer transverse diameter and 40 mm long. Ten stents were implanted in 10 dogs whose tracheal cartilages had been previously broken. The stents were first cooled in ice water to reduce their diameter and then inserted into the target site. The wire was warmed to body temperature and recovered its initial shape within 10 sec. The dogs were killed for examination between 1 week and 6 months after implantation. All the stents were located at the implantation sites and were patent. Tissue reactions, such as ulceration and granulation formation, were less severe than in those with previously implanted non-silicone covered stents. Microscopic observation showed that the wires became gradually covered with epithelium within 2 months. This transluminal technique for preserving airway patency shows promise for clinical application.

Stent implantation into the tracheo-bronchial system in rabbits: histopathologic sequelae in bare metal vs. drug-eluting stents.

PubMed

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.

Cost-utility analysis of stenting versus endarterectomy in the International Carotid Stenting Study.

PubMed

Morris, Stephen; Patel, Nishma V; Dobson, Joanna; Featherstone, Roland L; Richards, Toby; Luengo-Fernandez, Ramon; Rothwell, Peter M; Brown, Martin M

2016-06-01

The International Carotid Stenting Study was a multicenter randomized trial in which patients with symptomatic carotid artery stenosis were randomly allocated to treatment by carotid stenting or endarterectomy. Economic evidence comparing these treatments is limited and inconsistent. We compared the cost-effectiveness of stenting versus endarterectomy using International Carotid Stenting Study data. We performed a cost-utility analysis estimating mean costs and quality-adjusted life years per patient for both treatments over a five-year time horizon based on resource use data and utility values collected in the trial. Costs of managing stroke events were estimated using individual patient data from a UK population-based study (Oxford Vascular Study). Mean costs per patient (95% CI) were US$10,477 ($9669 to $11,285) in the stenting group (N = 853) and $9669 ($8835 to $10,504) in the endarterectomy group (N = 857). There were no differences in mean quality-adjusted life years per patient (3.247 (3.160 to 3.333) and 3.228 (3.150 to 3.306), respectively). There were no differences in adjusted costs between groups (mean incremental costs for stenting versus endarterectomy $736 (95% CI -$353 to $1826)) or adjusted outcomes (mean quality-adjusted life years gained -0.010 (95% CI -0.117 to 0.097)). The incremental net monetary benefit for stenting versus endarterectomy was not significantly different from zero at the maximum willingness to pay for a quality-adjusted life year commonly used in the UK. Sensitivity analyses showed little uncertainty in these findings. Economic considerations should not affect whether patients with symptomatic carotid stenosis undergo stenting or endarterectomy. © 2016 World Stroke Organization.

Investigation on the potential of thulium-fibre-laser irradiation for in-stent tissue ablation (Conference Presentation)

NASA Astrophysics Data System (ADS)

Sroka, Ronald; Frank, Johannes; Reichenberger, Frank; Behr, J.; Gesierich, Wolfgang

2017-04-01

Granulation and tumor regrowth in the area of bronchi stent implants may result in restenosis. It had been shown that by means of Thulium-Fibre-Laser (TFL) a controlled ablation and reduction of the tissue within the stent could be performed. When using Nd:YAG irradiation there is risk for explosive flames, burns of fibre and stent, ruptures of stent meshes as well as perforation of stent and cover. Therefore it was the aim to investigate the safety margin when using TFL. Four different types of clinical used stents (with/without cover) were fixed to pig trachea tissue. Irradiation was performed by fibre assisted TFL-1940nm-laser irradiation while laser power, light application duration and distance, as well as oxygen percentage and contamination were varied. In case of Nitinol-stents rupture were observed at power levels >=7W or distances of <5mm, oxygen conc. of 40% result in increased flame appearance. Polyurethan-covers were ruptured at each variable, flame appeared at 5W. Silicon-stents were destroyed at power levels of about 5W and distances of <5mm and additionally 30%-oxygen or contamination either by blood or soot result in increased appearance of burns and flames. Based upon these observations in clinical TFL-irradiation the distance should >=5 mm and the power level should be <=6W. Furthermore the oxygen conc. should not exceed 30% and short term continuous irradiation of less than 15s exposition should be considered. In case of Silicon-stents light application on contaminated area should be avoided.

Customized Hinged Covered Metallic Stents for the Treatment of Benign Main Bronchial Stenosis.

PubMed

Han, Xinwei; Al-Tariq, Quazi; Zhao, Yanle; Li, Lei; Cheng, Zhe; Wang, Huaqi; Liu, Chao; Jiao, Dechao; Wu, Gang

2017-08-01

To address the limitations of silicone stents, we designed a hinged self-expandable covered metallic stent. The aim of this study was to evaluate the safety and efficacy of the customized stents in clinical applications. This was a retrospective analysis. Under conscious sedation and local anesthesia, the stents were implanted or removed by interventional radiologists, with fluoroscopic guidance. Of 24 patients with benign main bronchial stenosis, stents were successfully placed in 21 (87.5%). The low-pressure balloon before dilation failed in 1 case (4.17%) of left main bronchial cicatricial stenosis. In 2 other cases (8.33%), stent placement was abandoned. Stents were successfully removed between 29 and 103 days after the procedure. After stent removal, the follow-up lasted for at least 12 months. Restenosis occurred only in 1 case (4.55%) owing to bronchial collapse 3 days after stent removal. Dyspnea occurred in another case (4.55%) at 2 months after retrieval; recurrence was confirmed using bronchoscopy, leading to a left pneumonectomy. The described procedure is safe and easy to be performed and avoids the use of intubation, bronchoscopy, and general anesthesia. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

High-definition computed tomography for coronary artery stent imaging: a phantom study.

PubMed

Yang, Wen Jie; Chen, Ke Min; Pang, Li Fang; Guo, Ying; Li, Jian Ying; Zhang, Huang; Pan, Zi Lai

2012-01-01

To assess the performance of a high-definition CT (HDCT) for imaging small caliber coronary stents (≤ 3 mm) by comparing different scan modes of a conventional 64-row standard-definition CT (SDCT). A cardiac phantom with twelve stents (2.5 mm and 3.0 mm in diameter) was scanned by HDCT and SDCT. The scan modes were retrospective electrocardiography (ECG)-gated helical and prospective ECG-triggered axial with tube voltages of 120 kVp and 100 kVp, respectively. The inner stent diameters (ISD) and the in-stent attenuation value (AV(in-stent)) and the in-vessel extra-stent attenuation value (AV(in-vessel)) were measured by two observers. The artificial lumen narrowing (ALN = [ISD - ISD(measured)]/ISD) and artificial attenuation increase between in-stent and in-vessel (AAI = AV(in-stent) - AV(in-vessel)) were calculated. All data was analyzed by intraclass correlation and ANOVA-test. The correlation coefficient of ISD, AV(in-vessel) and AV(in-stent) between the two observers was good. The ALNs of HDCT were statistically lower than that of SDCT (30 ± 5.7% versus 35 ± 5.4%, p < 0.05). HDCT had statistically lower AAI values than SDCT (15.7 ± 81.4 HU versus 71.4 ± 90.5 HU, p < 0.05). The prospective axial dataset demonstrated smaller ALN than the retrospective helical dataset on both HDCT and SDCT (p < 0.05). Additionally, there were no differences in ALN between the 120 kVp and 100 kVp tube voltages on HDCT (p = 0.05). High-definition CT helps improve measurement accuracy for imaging coronary stents compared to SDCT. HDCT with 100 kVp and the prospective ECG-triggered axial technique, with a lower radiation dose than 120 kVp application, may be advantageous in evaluating coronary stents with smaller calibers (≤ 3 mm).

One Year Outcomes of 101 BeGraft Stent Grafts used as Bridging Stents in Fenestrated Endovascular Repairs.

PubMed

Spear, Rafaelle; Sobocinski, Jonathan; Hertault, Adrien; Delloye, Matthieu; Azzauiu, Richard; Fabre, Dominique; Haulon, Stéphan

2018-04-01

To evaluate the outcomes of the second generation BeGraft balloon expandable covered stent Graft System (Bentley InnoMed, Hechingen, Germany) implanted as bridging stent grafts during fenestrated endovascular aortic repair (FEVAR) of complex aneurysms. This was a single centre prospective study including all consecutive patients treated by FEVAR performed with second generation BeGraft stent grafts as bridging stents. Demographics of patients, diameter and length of the bridging stent grafts, technical success, re-interventions, occlusions, post-operative events, and imaging (Cone Beam CT and/or CT scan, and contrast enhanced ultrasound) were prospectively collected in an electronic database. Duplex ultrasound was performed before discharge and at 6 month follow-up. At 1 year, patients were evaluated clinically and by imaging (CT and ultrasound). Between November 2015 and September 2016, 39 consecutive patients (one woman) were treated with custom made fenestrated endografts (2-5 fenestrations) for complex aneurysms or type 1 endoleak after EVAR, using a variety of bridging stents including the BeGraft. All 101 BeGraft stent grafts were successfully delivered and deployed. There was no in hospital mortality. Early fenestration patency rate was 99% (96/97); the sole target vessel post-operative occlusion was secondary to a dissection of the renal artery distal to the stent. Complementary stenting was unsuccessful in recovering renal artery patency; bilateral renal stent occlusion was observed in the same patient on a CT scan performed 2 months after the procedure. He required post-operative dialysis. No additional renal impairment was observed. During follow-up (median 13 months [11-15]), all fenestrations stented with BeGraft stent grafts remained patent (95/97, 98%). One type 1b endoleak was detected and treated (2.6%). BeGraft stent grafts used as bridging stents during FEVAR are associated with favourable outcomes at 1 year follow-up. Long-term follow-up is

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

PubMed

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.

Prospective Evaluation of Two iStent® Trabecular Stents, One iStent Supra® Suprachoroidal Stent, and Postoperative Prostaglandin in Refractory Glaucoma: 4-year Outcomes.

PubMed

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

Design and fabrication of novel polymeric biodegradable stents for small caliber blood vessels by computer-aided wet-spinning.

PubMed

Puppi, D; Pirosa, A; Lupi, G; Erba, P A; Giachi, G; Chiellini, F

2017-06-07

Biodegradable stents have emerged as one of the most promising approaches in obstructive cardiovascular disease treatment due to their potential in providing mechanical support while it is needed and then leaving behind only the healed natural vessel. The aim of this study was to develop polymeric biodegradable stents for application in small caliber blood vessels. Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (PHBHHx), a renewable microbial aliphatic polyester, and poly(ε-caprolactone), a synthetic polyester approved by the US Food and Drug Administration for different biomedical applications, were investigated as suitable polymers for stent development. A novel manufacturing approach based on computer-aided wet-spinning of a polymeric solution was developed to fabricate polymeric stents. By tuning the fabrication parameters, it was possible to develop stents with different morphological characteristics (e.g. pore size and wall thickness). Thermal analysis results suggested that material processing did not cause changes in the molecular structure of the polymers. PHBHHx stents demonstrated great radial elasticity while PCL stents showed higher axial and radial mechanical strength. The developed stents resulted able to sustain proliferation of human umbilical vein endothelial cells within two weeks of in vitro culture and they showed excellent results in terms of thromboresistivity when in contact with human blood.

Foam-rubber stents for skin grafts.

PubMed

Larson, P O

1990-09-01

A variety of stents are used to immobilize skin grafts and to hold them firmly to the recipient site. Tie-down stents, the most common type, are constructed from bulky, sterile dressing and are overtied with suture material. These stents are often cumbersome to apply. As an alternative, stents made from foam-rubber pads (Reston, 3M Company, St. Paul, MN) were stapled over skin grafts. These stents could be applied quickly, and they maintain continuous, uniform pressure on the immobilized grafts.

Fixation of silicone stents in the subglottic trachea: preventing stent migration using a fixation apparatus.

PubMed

Miwa, Keisuke; Takamori, Shinzo; Hayashi, Akihiro; Fukunaga, Mari; Shirouzu, Kazuo

2004-12-01

Silicone stents are widely used to treat benign or malignant airway stenosis. However, since straight silicone stents placed into the subglottic trachea to treat stenosis display a high risk of migration, novel approaches are required. The present report outlines our method of external fixation for silicone stents in the subglottic trachea. This technique utilizes a fixation apparatus, is readily performed, and may help to overcome the hesitation seen in placing silicone stents for subglottic tracheal stenosis.

Initial experience with a new biodegradable airway stent in children: Is this the stent we were waiting for?

PubMed

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.

Effect on Intimal Hyperplasia of Dexamethasone Released from Coated Metal Stents Compared with Non-Coated Stents in Canine Femoral Arteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strecker, Ernst-Peter; Gabelmann, Andreas; Boos, Irene

1998-11-15

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

The Incidence and Risk Factors of In-Stent Restenosis for Vertebrobasilar Artery Stenting.

PubMed

Zheng, Dai; Mingyue, Zhu; Wei, Shi; Min, Li; Wanhong, Chen; Qiliang, Dai; Yongjun, Jiang; Xinfeng, Liu

2018-02-01

In-stent restenosis (ISR) remains a challenge for vertebrobasilar artery stenting (VBAS). We aimed to investigate the incidence and risk factors of ISR. This was a retrospective study. From July 28, 2005, to July 30, 2015, patients who received VBAS with an angiographic follow-up time of 6 to 12 months after surgery were enrolled. The clinical and angiographic issues were recorded and analyzed. In total, 283 patients with 335 stents were incorporated into the study. Vertebral ostial lesions accounted for 73.4% (246/335) of the lesions. During the follow-up period, 58 patients with 60 stents experienced ISR (>50%). Stepwise logistic regression analysis showed that the degree of residual stenosis, stent diameter, and alcohol consumption were independent predictors of ISR. Our study demonstrated the incidence and risk factors of ISR after VBAS. This retrospective study with the largest cohort to date provided insight into the occurrence of ISR after VBAS. Copyright © 2017 Elsevier Inc. All rights reserved.

Internal stenting in malignant biliary obstruction.

PubMed

Cowling, M G; Adam, A N

2001-03-01

Internal stenting in inoperable malignant biliary obstruction plays an important role in patient management. Surgical bypass may still be undertaken where there is also duodenal obstruction, though the need for gastroenterostomy may be reduced with the increasing use of metallic stents for the relief of malignant gastric outlet obstruction. Stents may be placed endoscopically or percutaneously, though in most centers the endoscopic route is usually tried first, with the percutaneous route being reserved for endoscopic failures. Plastic and self-expanding metallic biliary stents are available, each with its own advantages and disadvantages. In general, longer periods of patency are observed with metallic stents, though they are more expensive. Plastic stents can be changed endoscopically relatively easily when they have blocked, and in practice it is common for plastic stents to be inserted via this route for initial biliary drainage. If there is prolonged survival thereafter, many workers insert a metallic stent in an attempt to reduce the number of interventions required. If the percutaneous route is being employed, the histologic diagnosis has been confirmed, and the malignancy is inoperable, our practice is to use a self-expanding metallic stent, as the delivery system is relatively small and subsequent occlusion less likely.

Percutaneous intraductal radiofrequency ablation for treatment of biliary stent occlusion: A preliminary result.

PubMed

Xia, Ning; Gong, Ju; Lu, Jian; Chen, Zhi-Jin; Zhang, Li-Yun; Wang, Zhong-Min

2017-03-14

To assess the feasibility and effectiveness of a novel application of percutaneous intraductal radiofrequency (RF) for the treatment of biliary stent obstruction. We specifically report a retrospective study presenting the results of percutaneous intraductal RF in patients with biliary stent occlusion. A total of 43 cases involving biliary stent obstruction were treated by placing an EndoHPB catheter and percutaneous intraductal RF was performed to clean stents. The stent patency was evaluated by cholangiography and follow-up by contrast enhanced computed tomography or ultrasound after the removal of the drainage catheter. Following the procedures, of the 43 patients, 40 survived and 3 died with a median survival of 80.5 (range: 30-243) d. One patient was lost to follow-up. One patient had the stent patent at the time of last follow-up. Two patients with stent blockage at 35 d and 44 d after procedure underwent percutaneous transhepatic drain insertion only. The levels of bilirubin before and after the procedure were 128 ± 65 μmol/L and 63 ± 29 μmol/L, respectively. There were no related complications (haemorrhage, bile duct perforation, bile leak or pancreatitis) and all patients' stent patency was confirmed by cholangiography after the procedure, with a median patency time of 107 (range: 12-180) d. This preliminary clinical study demonstrated that percutaneous intraductal RF is safe and effective for the treatment of biliary stent obstruction, increasing the duration of stent patency, although randomized controlled trials are needed to confirm the effectiveness of this approach.

Percutaneous intraductal radiofrequency ablation for treatment of biliary stent occlusion: A preliminary result

PubMed Central

Xia, Ning; Gong, Ju; Lu, Jian; Chen, Zhi-Jin; Zhang, Li-Yun; Wang, Zhong-Min

2017-01-01

AIM To assess the feasibility and effectiveness of a novel application of percutaneous intraductal radiofrequency (RF) for the treatment of biliary stent obstruction. METHODS We specifically report a retrospective study presenting the results of percutaneous intraductal RF in patients with biliary stent occlusion. A total of 43 cases involving biliary stent obstruction were treated by placing an EndoHPB catheter and percutaneous intraductal RF was performed to clean stents. The stent patency was evaluated by cholangiography and follow-up by contrast enhanced computed tomography or ultrasound after the removal of the drainage catheter. RESULTS Following the procedures, of the 43 patients, 40 survived and 3 died with a median survival of 80.5 (range: 30-243) d. One patient was lost to follow-up. One patient had the stent patent at the time of last follow-up. Two patients with stent blockage at 35 d and 44 d after procedure underwent percutaneous transhepatic drain insertion only. The levels of bilirubin before and after the procedure were 128 ± 65 μmol/L and 63 ± 29 μmol/L, respectively. There were no related complications (haemorrhage, bile duct perforation, bile leak or pancreatitis) and all patients’ stent patency was confirmed by cholangiography after the procedure, with a median patency time of 107 (range: 12-180) d. CONCLUSION This preliminary clinical study demonstrated that percutaneous intraductal RF is safe and effective for the treatment of biliary stent obstruction, increasing the duration of stent patency, although randomized controlled trials are needed to confirm the effectiveness of this approach. PMID:28348491

Effect of Covered Metallic Stents Compared With Plastic Stents on Benign Biliary Stricture Resolution

PubMed Central

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 < .001). Given the prespecified noninferiority margin of −15%, the

Subintimal Recanalization of Occluded Stents: The Substent Technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Diamantopoulos, Athanasios, E-mail: adiamant@upatras.gr; Katsanos, Konstantinos; Spiliopoulos, Stavros

2013-08-01

PurposeApplication of metal stents is complicated by neointimal hyperplasia leading to vessel restenosis and reocclusion. Treatment options in cases presenting with complete occlusion of the stented segment and recurrent critical limb ischemia (CLI) are limited. We present the option of the subintimal/substent technique in dealing with occluded stents.MethodsThe study included patients presenting with recurrent CLI due to impaired blood flow as a result of complete occlusion of previously inserted metal stents and unsuccessful intraluminal crossing of the lesion via either the antegrade or retrograde approach. In these cases, crossing the occlusion through the subintimal/substent plane was attempted. Primary end pointsmore » included technical success, safety of the procedure, clinical improvement, and limb salvage, while secondary end points were patient survival, primary patency, and vessel restenosis rates at 1-year follow-up. Study end points were calculated by Kaplan-Meier survival analysis.ResultsBetween July 2006 and October 2011, a total of 14 patients (mean age 69.14 {+-} 12.59 years, 12 men) were treated with the substent technique and included in the analysis. Technical success rate was 85.71 % (12 of 14), with a total lesion length of 193.57 {+-} 90.78 mm. The mean occluded stented segment length was 90.21 {+-} 44.34 mm. In 10 (83.33 %) of 12 cases, a new stent had to be placed by the side of the old occluded one, while the remaining two cases (16.67 %) were treated only with balloon angioplasty. No serious adverse events were noted during the immediate postprocedural period. All successfully treated patients improved clinically. Estimated limb salvage was 90.9 %, and patient survival rate was 90.0 % at 1 year's follow-up. Primary patency was 45.50 % and vessel restenosis 77.30 %.ConclusionSubintimal recanalization of occluded metal stents through the substent plane is a valuable alternative treatment option, especially in patients with recurrent CLI

Covered metal stent or multiple plastic stents for refractory pancreatic ductal strictures in chronic pancreatitis: a systematic review.

PubMed

Shen, Yonghua; Liu, Mingdong; Chen, Min; Li, Yunhong; Lu, Ying; Zou, Xiaoping

2014-01-01

Refractory chronic pancreatitis has been proposed as a challenge for endoscopists following routine single plastic stenting. However, data on the efficacy and safety of further endoscopic stenting are still controversial. The current systematic review aimed to assess the efficacy and safety of placement of fully covered self-expandable metal stent (FCSEMS) and multiple plastic stents. Databases including MEDLINE, EMBASE, the Cochrane Library, CBM, CNKI, VIP, and WANFANG Database were used to search relevant trials. Published studies were assessed by using well-defined inclusion and exclusion criteria. The process was independently performed by two investigators. A total of 5 studies provided data of 80 patients. Forest plots and publication bias were not carried out because few studies were relevant and screened studies were all case series. The technical success rate was 100% both in placement of FCSEMS and multiple plastic stents. The functional success rate after placement of FCSEMS was 100%, followed by multiple plastic stents (94.7%). Complications occurred 26.2% after FCSEMS placement, which was not described in detail in multiple plastic stents. The stent migration rate was 8.2% for FCSEMS and 10.5% for multiple plastic stents. Reintervention rate was 9.8% for FCSEMS and 15.8% for multiple plastic stents. Pain improvement rate was 85.2% for FCSEMS and 84.2% for multiple plastic stents. FCSEMS appeared to be no significant difference with multiple plastic stents in treatment of refractory chronic pancreatitis. We need to develop more investigations. Copyright © 2014 IAP and EPC. Published by Elsevier B.V. All rights reserved.

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

PubMed

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

2014-01-01

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

Covered Balloon-Expanding Stents in Airway Stenosis.

PubMed

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 (P<0.05). Self-reported respiratory symptoms improved in 14 patients (78%, P<0.05). Radiographic improvement post Atrium iCAST stent 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.

[The application of Y-shaped self-expandable covered metal stents in the thoracostomach-airway fistula: a single center, 11 years experience].

PubMed

Fang, Yi; Li, Tengfei; Han, Xinwei; Wu, Gang; Ren, Jianzhuang; Ren, Kewei; Lu, Huibin; Zhang, Quanhui; Li, Zongming

2015-08-01

To investigate the clinical feasibility and efficacy of Y-shaped self-expandable covered metal stents (Y-stents) in the management of thoracostomach-airway fistula. Retrospective analysis was performed for 108 patients treated for thoracostomach-airway fistula with Y-shaped self-expandable coated metal stents between April 2003 and October 2014. Y-stents were designed based on the dimensions of trachea and bronchus and sites of the fistula and then were inserted under DSA monitoring. There were 65 cases with single big Y-stent placement, 26 cases with single small Y-stent placement, 23 cases with double Y-stents placement, and 1 case with 3 Y-stents placement. Stent implantation was successfully accomplished with single manipulation in all patients. Complete occlusion of the fistula was obtained in 104 patients after the primary manipulation, and 4 patients required a secondary manipulation where a double Y-stents was inserted because of failure of primary manipulate. Ninety-two patients completed the follow-up , while 16 were lost. Fifty-nine patients died while 33 were alive with marked improvement in their quality of life. The placement of Y-stents can effectively occlude the thoracostomach-airway fistula in patients who had had the esophageal tumors resected. The technique is not only feasible but reliable to improve the quality of life of the patients.

Impact of stent length on clinical outcomes of first-generation and new-generation drug-eluting stents.

PubMed

Konishi, Hirokazu; Miyauchi, Katsumi; Dohi, Tomotaka; Tsuboi, Shuta; Ogita, Manabu; Naito, Ryo; Kasai, Takatoshi; Tamura, Hiroshi; Okazaki, Shinya; Isoda, Kikuo; Daida, Hiroyuki

2016-04-01

The aim of this study is to compare first- and new-generation drug-eluting stents (DESs) which are implanted in long lesion. Stent length is known to be a predictor of adverse events after percutaneous coronary intervention (PCI), even with the first-generation DESs. The introduction of new-generation DESs has reduced the rates of adverse clinical events. However, the impact of stent length on long-term clinical outcomes is not well known. A total of 1181 consecutive patients who underwent PCI using either a first-generation DES (n = 885) or a new-generation DES (n = 296) between 2004 and 2011 were investigated. In each of the stent groups, the patients were divided into two groups by stent length (>32 and ≤32 mm) and compared. During the follow-up period, the incidence of major adverse cardiac events (MACEs) was significantly higher for patients with long stents implanted than with short stents (P < 0.01; log-rank test) in the first-generation DES group. However, there was no difference in the incidence of MACEs between the long- and short-stent groups in the new-generation DES group (P = 0.24; log-rank test). On multivariate Cox regression analysis, stent length was not associated with adverse events in the new-generation DES groups [hazard ratio (HR) 0.87; 95 % confidence interval (95 % CI) 0.71-1.04; P = 0.14]. Implanted stent length was significantly associated with a higher risk of MACEs in patients who received first-generation DESs, but not in patients who received the new-generation DESs.

Ex-vivo assessment of anchoring force of covered biflanged metal stent and covered self-expandable metal stent for interventional EUS.

PubMed

Tonozuka, Ryosuke; Yunoki, Shunji; Itoi, Takao; Sofuni, Atsushi; Tsuchiya, Takayoshi; Ishii, Kentaro; Tanaka, Reina; Honjo, Mitsuyoshi; Mukai, Shuntaro; Fujita, Mitsuru; Yamamoto, Kenjiro; Asai, Yasutsugu; Matsunami, Yukitoshi; Kurosawa, Takashi; Kojima, Hiroyuki; Nagakawa, Yuichi; Nagakawa, Yoshiyasu

2018-06-05

EUS-guided transmural drainage (EUS-TD) using a covered biflanged metal stent (CBFMS) and a conventional tubular biliary covered self-expandable metal stent (CSEMS) has recently been performed by EUS experts. However, appropriate traction force of the sheath to prevent the migration during stent deployment is well unknown. Herein, we assessed the anchoring force (AF) of the distal flange in CBFMSs and CSEMSs. The AFs of 4 CBFMSs (Stents AX, NG, PL, and SX) and 6 CSEMSs (Stents BF, BP, EG, HN, SP, and WF) were compared in an ex vivo setting. We assessed the AF produced by each stent using an EUS-TD model and an EUS-guided hepaticogastrostomy (EUS-HGS) model consisting of sheet-shaped specimens of the stomach, gelatin gel, and gelatin tubes. For CBFMSs, the maximum AF of Stent AX was significantly higher than those of Stents PL and SX (P < 0.05) in the porcine model. In the gelatin series, all stents except Stent NG showed a nearly similar AF. For CSEMSs, Stents HN, EG, BF, and WF showed gradual AF elevation in the porcine stomach. Stents SP and BP showed a lower AF than the other 4 stents. For the gelatin setting, the maximum AF of Stents HN, EG, and WF were higher than those of the other stents regardless of the type of specimens. The significance of the AF and traction distance according to the property of various CBFMSs and CSEMSs could be elucidated using ex-vivo models. This article is protected by copyright. All rights reserved.

Multifaceted prospects of nanocomposites for cardiovascular grafts and stents

PubMed Central

Vellayappan, Muthu Vignesh; Balaji, Arunpandian; Subramanian, Aruna Priyadarshini; John, Agnes Aruna; Jaganathan, Saravana Kumar; Murugesan, Selvakumar; Supriyanto, Eko; Yusof, Mustafa

2015-01-01

Cardiovascular disease is the leading cause of death across the globe. The use of synthetic materials is indispensable in the treatment of cardiovascular disease. Major drawbacks related to the use of biomaterials are their mechanical properties and biocompatibility, and these have to be circumvented before promoting the material to the market or clinical setting. Revolutionary advancements in nanotechnology have introduced a novel class of materials called nanocomposites which have superior properties for biomedical applications. Recently, there has been a widespread recognition of the nanocomposites utilizing polyhedral oligomeric silsesquioxane, bacterial cellulose, silk fibroin, iron oxide magnetic nanoparticles, and carbon nanotubes in cardiovascular grafts and stents. The unique characteristics of these nanocomposites have led to the development of a wide range of nanostructured copolymers with appreciably enhanced properties, such as improved mechanical, chemical, and physical characteristics suitable for cardiovascular implants. The incorporation of advanced nanocomposite materials in cardiovascular grafts and stents improves hemocompatibility, enhances antithrombogenicity, improves mechanical and surface properties, and decreases the microbial response to the cardiovascular implants. A thorough attempt is made to summarize the various applications of nanocomposites for cardiovascular graft and stent applications. This review will highlight the recent advances in nanocomposites and also address the need of future research in promoting nanocomposites as plausible candidates in a campaign against cardiovascular disease. PMID:25897223

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

PubMed

Tsutsumi, Koichiro; Kato, Hironari; Tomoda, Takeshi; Matsumoto, Kazuyuki; Sakakihara, Ichiro; Yamamoto, Naoki; Noma, Yasuhiro; Sonoyama, Takayuki; Okada, Hiroyuki; Yamamoto, Kazuhide

2012-12-07

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

Fluoroscopically guided placement of self-expandable metallic stents and stent-grafts in the treatment of acute malignant colorectal obstruction.

PubMed

Kim, Honsoul; Kim, Seung Hyoung; Choi, Sun Young; Lee, Kwang-Hun; Won, Jong Yoon; Lee, Do Yun; Lee, Jong Tae

2008-12-01

To evaluate the technical feasibility and clinical effectiveness of fluoroscopically guided placement of self-expandable metallic stents and stent-grafts for acute malignant colorectal obstruction. Radiologic images and clinical reports of 42 patients (22 men, 20 women; age range, 28-93 years; median age, 65.5 years) who underwent fluoroscopically guided colorectal stent insertion without endoscopic assistance for acute malignant obstruction were reviewed retrospectively. Eighteen patients received bare stents as a bridge to surgery. Twenty-four patients received 27 insertions of either a bare stent (n = 15) or a stent-graft (n = 12) for palliation. The obstruction was located in the rectum (n = 8), sigmoid (n = 17), descending colon (n = 8), splenic flexure (n = 3), and transverse colon (n = 6). Clinical success, defined as more than 50% dilatation of the stent with subsequent symptomatic improvement, was achieved in 41 of the 42 patients (98%). No major procedure-related complications occurred. Minor complications occurred in eight of the 45 procedures (18%). No perioperative mortalities occurred within 1 month after surgery. In the palliative group, the median stent patency was 62 days (range, 0-1,014 days). There was no statistically significant difference in stent patency between the bare stents (range, 0-855 days; median, 68 days) and stent-grafts (range, 1-1,014 days; median, 81 days). Fluoroscopically guided placement of self-expandable metallic stents and stent-grafts for the relief of acute malignant colorectal obstruction was technically feasible without endoscopic assistance-even in lesions proximal to the splenic flexure and transverse colon-and clinically effective in both bridge to surgery and palliative management.

[Experimental study of an intratracheal stent made of shape memory alloy].

PubMed

Yoshimura, M; Tsugawa, C; Tsubota, N

1994-11-01

To develop a new prosthesis for treating tracheal stenosis and tracheobronchomalacia, we examined the usefulness of an intratracheal stent made of shape memory alloy (SMA), a titanium-nickel alloy composed of 50% of each metal. At its recovery temperature (37 degrees C), the SMA stent was designed to recall the memorized shape of a coil with a diameter of 5 or 6 mm and a length of 10 mm. For the present experiment, it was transformed to a smaller coil 3 mm in diameter at a low temperature (-50 degrees C) and then loaded into the prosthesis introducer tube. An experimental model of potentially fatal tracheomalacia was made surgically by cutting and fracturing the tracheal cartilages of rabbits and tracheal collapse was confirmed by rigid bronchoscope. The introducer tube with the SMA stent was inserted and then the prosthesis was advanced into the collapsed segment of the trachea using the stent pusher. The SMA stent warmed bo body temperature and recovered its memorized shape after 1-2 min. In 3 out of 8 rabbits, follow-up bronchoscopy performed at 6, 8, and 10 months after implantation revealed satisfactory patency of the SMA stent and the trachea. After follow-up, 3 animals were sacrificed for histological observation, which showed little proliferation of granulation tissue and no dislocation of the SMA stent from the malacic portion. The remaining 5 rabbits have been followed for 18-24 months and are doing well. We conclude that the SMA stent maintains good tracheal patency, causes little reaction in the tracheal wall, and is easy to handle. Thus, it shows the potential for clinical application.

Surface modification of esophageal stent materials by a polyethylenimine layer aiming at anti-cancer function.

PubMed

Zhang, Kun; Bai, Yuxin; Wang, Xiaofeng; Li, Qian; Guan, Fangxia; Li, Jingan

2017-08-01

Esophageal cancer is difficult to cure globally and possesses high mortality rate, and it is generally accepted that palliative care such as stent implantation is the main therapy method for esophageal cancer in later period. However, the restenosis caused by tumor cells and inflammatory cells seriously interferes the stent clinical application and limits its long-term services. To solve this problem, series of drug delivery stents were developed and proven rather effective in the early stage of implantation, but more serious restenosis occurred after the drug delivery was over, which endangered the patients' life. Therefore, endowing the esophageal stent continuous anti-cancer function become an ideal strategy for inhibiting the restenosis. In this contribution, the functional layer composed of polydopamine (PDA) and Poly-ethylenimine (PEI) with series of molecular weights (MW, 1.8 × 10 3 , 1 × 10 4 , 2.5 × 10 4 and 7 × 10 4  Da) were fabricated onto the esophageal stent material 317L stainless steel (317L SS) surface. The surface characterization including amine quantitative, atomic force microscopy (AFM) and water contact angle measurement indicated successful preparation of the PDA/PEI layer. The Eca109 cells culture results proved that the PDA/PEI layers significantly improve Eca109 cells apoptosis and necrosis, suggesting excellent anti-cancer function. In addition, we also found that the anti-cancer function of the PDA/PEI layers was positively correlated to the immobilized PEIs' MW. All the results demonstrated the potential application of the PDA/PEI layers on the surface modification of esophageal stent for continuous anti-cancer function. It is generally accepted that the restenosis caused by tumor cells seriously interferes the esophageal stent clinical application. Thus, endowing the esophageal stent continuous anti-cancer function is the ideal strategy for inhibiting the restenosis. In this work, we fabricated functional layers

Outcomes of spot stenting versus long stenting after intentional subintimal approach for long chronic total occlusions of the femoropopliteal artery.

PubMed

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

2015-03-01

This study sought to compare the outcomes of spot stenting versus long stenting after intentional subintimal approach for long femoropopliteal chronic total occlusions (CTO). The optimal stenting strategy following the subintimal recanalization of long femoropopliteal chronic total occlusions has not been investigated. A total of 196 limbs in 163 patients, implanted with bare nitinol stents after subintimal approach in long femoropopliteal occlusions (lesion length 25 ± 8 cm), were retrospectively analyzed. The primary patency was compared between spot stenting (n = 129) and long stenting (n = 67). Baseline characteristics and immediate procedural results were similar between groups. Adjusted-primary patency (47% vs. 77%, p < 0.001) and adjusted-freedom from target lesion revascularization (52% vs. 84%, p < 0.001) at 2 years were significantly lower in the long stenting group than in the spot stenting group. The incidence of stent fracture, fracture type, and restenosis pattern did not differ between groups. Long stenting was an independent predictor of restenosis (hazard ratio [HR]: 2.0) along with other risk factors such as nonuse of clopidogrel (HR: 3.3) or cilostazol (HR: 2.2), small stent diameter (HR: 0.6), poor run-off (HR: 1.9), and post-procedural ankle-brachial index (HR: 0.1). Compared with spot stenting after adjustment using inverse probability of treatment weighting, long stenting, especially involving the P2 or P3 segment of the popliteal artery, was independently associated with 7.5-fold increases in restenosis risk (p < 0.001). The primary patency was significantly higher with spot stenting than with long stenting following subintimal approach for long femoropopliteal chronic total occlusions. The risk of restenosis was especially higher when long stenting was extended to the distal popliteal artery. Copyright © 2015 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Retreatment of recanalized aneurysms after Y-stent-assisted coil embolization with double enterprise stents: case report and systematic review of the literature.

PubMed

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.

Angioplasty and stent placement - carotid artery

MedlinePlus

... 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 ...

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

PubMed

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.

Application of Y-shaped, coated self-expandable metallic stents for anastomotic stenosis after gastrojejunostomy (Billroth II).

PubMed

Li, Teng-Fei; Wu, Gang; Han, Xin-Wei; Shui, Shao-Feng; Ren, Jian-Zhuang; Li, Zhen; Ren, Ke-Wei

2017-01-01

Anastomotic stenosis is an infrequent but life-threatening complication after gastrojejunostomy (Billroth II). Tubular or single tubular stents have limited efficacy due to the particular anatomy. To assess the feasibility of a Y-shaped, fully-coated, self-expandable, metallic stent (SEMS) for anastomotic stenosis after gastrojejunostomy (Billroth II). Between January 2008 and August 2014, 14 patients (10 with gastric carcinoma and four with duodenal ulcers) had anastomotic stenoses following Billroth II reconstructions. Eight patients with gastric cancer had tumor recurrence near the anastomosis; two had benign strictures. The four duodenal ulcer patients had benign stenoses. An integrated Y-shaped, fully coated SEMS was designed to accord with the anatomy of residual gastrojejunal anastomotic strictures. Fourteen stents were inserted under fluoroscopic control. Follow-up was at 1, 3, 9, and 12 months, and then annually. All 14 stents were inserted successfully at the first attempt with a technical success rate of 100%. After stenting, abdominal symptoms resolved in all patients. All patients were followed up for 4-27 months (mean, 13.9 months). One of the eight recurrent cases died of multiple tumor metastases and liver failure after 7 months, without obstruction symptoms. In all six patients with benign anastomotic stenosis, the stents were removed successfully without complication and with no evidence of restenosis based on clinical evaluation and imaging. A Y-shaped, fully-coated SEMS proved to be a feasible and minimally invasive procedure for treating anastomotic stenosis after gastrojejunostomy (Billroth II). © The Foundation Acta Radiologica 2016.

In vitro stent lumen visualisation of various common and newly developed femoral artery stents using MR angiography at 1.5 and 3 tesla.

PubMed

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 < 0.05) at 1.5 and 3 T. Maximum visible 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.

Self-Expandable Metallic Stent Placement in Malignant Gastric Outlet Obstruction: A Comparison Between 2 Brands of Stents.

PubMed

Ye, Bing-Wei; Lee, Kuei-Chuan; Hsieh, Yun-Cheng; Li, Chung-Pin; Chao, Yee; Hou, Ming-Chih; Lin, Han-Chieh

2015-07-01

Malignant gastric outlet obstruction is a late complication of intraabdominal malignancy. Self-expandable metallic stent placement has been a safe palliative treatment to relieve obstructive symptoms. We aimed to assess the efficacy and safety of metallic stents in our patients and analyzed the clinical outcome of different brands. Seventy-one patients with inoperable gastric outlet obstruction receiving WallFlex enteral stents (WallFlex group) or Bonastents (Bonastent group) since April 2010 were analyzed retrospectively. The overall technical and clinical success rates of stent placement were 100% and 93%, respectively. The baseline characteristics and clinical outcomes including procedure-related complications, restenosis, and reintervention rates were comparable between the 2 groups. However, the Bonastent group had a higher rate of stent fracture than the WallFlex group (13.3% vs 0%, P = 0.03). The mean duration of overall stent patency was 132.7 days. The mean duration of survival was 181.9 days. Resumption of regular diet or low residual diet at day 7 after stent insertion predicted stent patency (hazard ratio [HR]: 0.28, P = 0.01). Cancer with gastric origin (HR: 0.25, P = 0.045) and poststent chemotherapy (HR: 0.38, P = 0.006) predicted lower mortality; however, peritoneal carcinomatosis (HR: 3.09, P = 0.04) correlated with higher mortality. Metallic stent placement is a safe and effective method for relieving gastric outlet obstruction. Except higher rate of stent fracture in the Bonastent group, there is no significant difference in clinical outcomes between the Bonastent group and the WallFlex group.

Comparison of retrievable stents and permanent stents for Budd-Chiari syndrome due to obstructive inferior vena cava.

PubMed

Bi, Yonghua; Chen, Hongmei; Ding, Penxu; Ren, Jianzhuang; Han, Xinwei

2018-05-30

To compare long-term outcomes of retrievable stents and permanent stents for BCS due to long-segment obstructive IVC. Between July 2000 and August 2016, 42 patients with BCS due to long-segment obstructive IVC were treated with retrievable stents (RS) and 41 patients were treated with permanent stents (PS). The retrievable stents was removed eventually after thrombus disappeared. Patients were subsequently followed-up by color Doppler sonography or CT scanning. All retrievable stent placements were successfully, and 37 retrievable stents were retrieved 8 to 29 days later. Forty-two stents were implanted in PS Group. One failure retrieval of retrievable stents occurred, and two failures of cannulations were found in PS Group. Two deaths may procedure-related and died from acute pulmonary thromboembolism perioperatively. One patient developed acute cerebral infarction and recovered after treatment. In PS Group, minor complications were found in 3 patients. The length of IVC lesion segment, length and thickness of IVC thrombus decreased significantly, and diameter of retrocaval IVC and diaphragm IVC increased significantly in both groups. During follow up, 3 patients died from liver failure in RS Group and 2 patients died in PS Group. RS Group showed a significantly higher primary patency rate than PS Group. Cumulative 1-, 3-, and 5-year secondary patency rates were 95.2%, 89.6%, 89.6% in RS Group, and 100%, 96.6%, 96.6% in PS Group (p= 0.7109). Retrievable stents is effective for BCS due to long-segment obstructive IVC, with a higher primary patency rate. This article is protected by copyright. All rights reserved.

Novel 3D-CT evaluation of carotid stent volume: greater chronological expansion of stents in patients with vulnerable plaques.

PubMed

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 < 0.05). A 3D-CT examination is useful for precisely measuring stent volume. Self-expanding stents in carotid arteries containing vulnerable plaques expand significantly more than those without such plaques in a follow-up period.

Flow diverter effect of LVIS stent on cerebral aneurysm hemodynamics: a comparison with Enterprise stents and the Pipeline device.

PubMed

Wang, Chao; Tian, Zhongbin; Liu, Jian; Jing, Linkai; Paliwal, Nikhil; Wang, Shengzhang; Zhang, Ying; Xiang, Jianping; Siddiqui, Adnan H; Meng, Hui; Yang, Xinjian

2016-07-02

The aim of this study was to quantify the effect of the new Low-profile Visualized Intraluminal Support (LVIS®D) device and the difference of fluid diverting effect compared with the Pipeline device and the Enterprise stent using computational fluid dynamics (CFD). In this research, we simulated three aneurysms constructed from 3D digital subtraction angiography (DSA). The Enterprise, LVIS and the Pipeline device were virtually conformed to fit into the vessel lumen and placed across the aneurysm orifice. Computational fluid dynamics analysis was performed to compare the hemodynamic differences such as WSS, Velocity and Pressure among these stents. Control referred to the unstented model, the percentage of hemodynamic changes were all compared to Control. A single LVIS stent caused more wall shear stress reduction than double Enterprise stents (39.96 vs. 30.51 %) and velocity (23.13 vs. 18.64 %). Significant reduction in wall shear stress (63.88 %) and velocity (46.05 %) was observed in the double-LVIS stents. A single Pipeline showed less reduction in WSS (51.08 %) and velocity (37.87 %) compared with double-LVIS stent. The double-Pipeline stents resulted in the most reduction in WSS (72.37 %) and velocity (54.26 %). Moreover, the pressure increased with minuscule extent after stenting, compared with the unstented model. This is the first study analyzing flow modifications associated with LVIS stents. We found that the LVIS stent has certain hemodynamic effects on cerebral aneurysms: a single LVIS stent caused more flow reductions than the double-Enterprise stent but less than a Pipeline device. Nevertheless, the double-LVIS stent resulted in a better flow diverting effect than a Pipeline device.

Stent-assisted coiling of intracranial aneurysms using LEO stents: long-term follow-up in 153 patients.

PubMed

Sedat, Jacques; Chau, Yves; Gaudart, Jean; Sachet, Marina; Beuil, Stephanie; Lonjon, Michel

2018-02-01

Coiling associated with placement of a self-expandable intracranial stent has improved the treatment of intracranial wide-necked aneurysms. Little is known, however, about the durability of this treatment. The purpose of this report is to present our experience with the LEO stent and to evaluate the complications, effectiveness, and long-term results of this technique. We analyzed the records of 155 intracranial unruptured aneurysms that were treated by stent-assisted coiling with a LEO stent between 2008 and 2012. Procedural, early post-procedural, and delayed complications were recorded. Clinical and angiographic follow-up of patients was conducted over a period of at least 36 months. No procedural mortality was observed. One-month morbidity was observed in 14 out of 153 patients (9,15%). One hundred thirty-eight patients (with 140 aneurysms) had clinical and angiographic follow-up for more than 36 months. No aneurysm rupture was observed during follow-up. Four patients presented an intra-stent stenosis at 8 months, and 6 patients who had an early recurrence were retreated. Final results showed 85% complete occlusion, 13% neck remnants, and 2% stable incomplete occlusion. Stent-assisted coiling with the LEO stent is a safe and effective treatment for unruptured intracranial aneurysms. The long-term clinical outcomes with the LEO stent are excellent with a high rate of complete occlusion that is stable over time.

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

PubMed

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/

A review of the iStent® trabecular micro-bypass stent: safety and efficacy

PubMed Central

Wellik, Sarah R; Dale, Elizabeth A

2015-01-01

There is a significant demand for procedures that can effectively treat glaucoma with low risk and good visual outcomes. To fill this void, procedures termed “minimally invasive glaucoma surgery”, are gaining in popularity. This review will focus on the safety and efficacy of one such minimally invasive glaucoma surgery procedure, the trabecular micro-bypass stent. This stent is intended to lower intraocular pressure by directly cannulating Schlemm’s canal and thereby enhancing aqueous outflow. Recent randomized controlled trials and case series have demonstrated the micro-bypass stent to be a relatively safe procedure, with limited complications and no serious adverse sequelae. The most common complication across all studies was stent obstruction or malposition, which generally did not result in any adverse outcome in vision or pressure control. In addition, increased rates of hypotony, choroidal hemorrhage, or infection were not seen with the micro-bypass stent in comparison to cataract surgery alone. PMID:25931808

Exclusion of Atherosclerotic Plaque from the Circulation Using Stent-Grafts: Alternative to Carotid Stenting with a Protection Device?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peynircioglu, Bora, E-mail: borapeynir@gmail.com; Geyik, Serdar; Yavuz, Kivilcim

2007-09-15

Purpose. To retrospectively assess the feasibility, safety, and clinical mid-term outcome of patients undergoing carotid artery stenting with stent-grafts. Methods. Over a 4 year period stent-grafts were used in the endovascular treatment of symptomatic internal carotid artery stenosis in 12 patients (2 women, 10 men, aged 47-83 (mean 64) years). Protection devices were not used. Possible microembolic complications were evaluated by magnetic resonance imaging (MRI) examinations of the brain before and the day after the procedure in all patients. Mean follow-up was 22 months (range 1-42 months), by Doppler ultrasonography and conventional angiography as well as clinical examination .Results. Themore » technical success rate was 100%. A total of 13 coronary stent-grafts were used. The mean stenosis rate (in terms of diameter) was 85% and the mean length of stent-grafts used was 20.9 mm. The mean diameter to which the stent-grafts were dilated was 4.66 mm. In-hospital complications occurred in 1 patient who suffered a minor femoral access hematoma that did not require transfusion or surgical decompression. Post-stenting diffusion-weighted MRI revealed several ipsilateral silent microemboli in only 1 case, which was completely asymptomatic. Two patients had a major stroke after 2 years of follow-up. Restenosis was found in 2 patients who underwent successful balloon dilatation followed by placement of a self-expandable bare stent within the stent-grafts. Conclusions. Stent-grafts may prevent microembolic complications during stenting of atherosclerotic carotid lesions in selected cases, offering immediate exclusion of the atherosclerotic lesion from the circulation by pressing the plaque against the vessel wall. Comparative, randomized studies in larger series of patients are needed with carotid-dedicated stent-graft designs.« less

Stent Thrombosis With Drug-Eluting Stents and Bioresorbable Scaffolds: Evidence From a Network Meta-Analysis of 147 Trials.

PubMed

Kang, Si-Hyuck; Chae, In-Ho; Park, Jin-Joo; Lee, Hak Seung; Kang, Do-Yoon; Hwang, Seung-Sik; Youn, Tae-Jin; Kim, Hyo-Soo

2016-06-27

This study sought to perform a systematic review and network meta-analysis to compare the relative safety and efficacy of contemporary DES and BVS. To improve outcomes of patients undergoing percutaneous coronary revascularization, there have been advances in the design of drug-eluting stents (DES), including the development of drug-eluting bioresorbable vascular scaffolds (BVS). Prospective, randomized, controlled trials comparing bare-metal stents (BMS), paclitaxel-eluting stents (PES), sirolimus-eluting stents (SES), Endeavor zotarolimus-eluting stents (E-ZES), cobalt-chromium (CoCr) everolimus-eluting stents (EES), platinum-chromium (PtCr)-EES, biodegradable polymer (BP)-EES, Resolute zotarolimus-eluting stents (R-ZES), BP biolimus-eluting stents (BP-BES), hybrid sirolimus-eluting stents (H [Orsiro]-SES), polymer-free sirolimus- and probucol-eluting stents, or BVS were searched in online databases. The primary endpoint was definite or probable stent thrombosis at 1 year. A total of 147 trials including 126,526 patients were analyzed in this study. All contemporary DES were superior to BMS and PES in terms of definite or probable stent thrombosis at 1 year. CoCr-EES, PtCr-EES, and H-SES were associated with significantly lower risk than BVS. CoCr-EES and H-SES were superior to SES and BP-BES. The risk of myocardial infarction was significantly lower with H-SES than with BVS. There were no significant differences regarding all-cause or cardiac mortality. Contemporary devices including BVS showed comparably low risks of repeat revascularization. Contemporary DES, including biocompatible DP-DES, BP-DES, and polymer-free DES, showed a low risk of definite or probable stent thrombosis at 1 year. BVS had an increased risk of device thrombosis compared with CoCr-EES, PtCr-EES, and H-SES. Data from extended follow-up are warranted to confirm the long-term safety of contemporary coronary devices. Copyright © 2016 American College of Cardiology Foundation. Published by

A Mechanobiological model for damage-induced growth in arterial tissue with application to in-stent restenosis

NASA Astrophysics Data System (ADS)

Fereidoonnezhad, B.; Naghdabadi, R.; Sohrabpour, S.; Holzapfel, G. A.

In-stent restenosis (ISR) is one of the main drawbacks of stent implementation which limits the long-term success of the procedure. Morphological changes occurring within the arterial wall due to stent-induced mechanical injury are a major cause for activation of vascular smooth muscle cells (VSMCs), and the subsequent development of ISR. Considering the theory of volumetric mass growth and adopting a multiplicative decomposition of the deformation gradient into an elastic part and a growth part, we present a mechanobiological model for ISR. An evolution equation is developed for mass growth of the neointima, in which the activation of VSMCs due to stent-induced damage (injury) and the proliferation rate of the activated cells are considered. By introducing the mass evolution into the mass balance equation, we obtain the evolution of the growth tensor over time. The model is implemented in a finite element code and the procedure of angioplasty is simulated, whereby the features of the proposed growth model are illustrated.

Investigation of adverse events associated with an off-label use of arterial stents and CE-marked iliac vein stents in the iliac vein: insights into developing a better iliac vein stent.

PubMed

Shida, Takuya; Umezu, Mitsuo; Iwasaki, Kiyotaka

2018-06-01

We analyzed the adverse events associated with an off-label use of arterial stents and CE-marked iliac vein stents for the treatment of iliac venous thromboembolism and investigated their relationships with the anatomical features of the iliac vein, to gain insights into the development of a better iliac vein stent. Reports of adverse events following the use of stents in the iliac vein were retrieved from the Manufacturer and User Facility Device Experience (MAUDE) database that contain suspected device-associated complications reported to the Food and Drug Administration. Data from 2006 to 2016 were investigated. The literature analysis was also conducted using PubMed, Cochrane Library, EMBASE, and Web of Science focusing on English articles published up to 4 October 2016. The analysis of 88 adverse events from the MAUDE database and 182 articles from the literature revealed that a higher number of adverse events had been reported following the use of arterial stents in the iliac vein compared to CE-marked iliac vein stents. While stent migration and shortening were reported only for the arterial stents, stent fracture and compression occurred regardless of the stent type, even though a vein does not pulsate. A study of the anatomical features of the iliac vein implies that bending, compression, and kink loads are applied to the iliac vein stents in vivo. For designing, developing, and pre-clinical testing of stents intended for use in the iliac vein, the above mechanical load environments induced by the anatomical features should be considered.

Acute ST-Elevation Myocardial Infarction after Coronary Stent Fracture.

PubMed

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.

Relation of Nickel Allergy with in-Stent Restenosis in Patients Treated with Cobalt Chromium Stents.

PubMed

Aliağaoğlu, Cihangir; Turan, Hakan; Erden, Ismail; Albayrak, Hülya; Ozhan, Hakan; Başar, Cengiz; Gürlevik, Zehra; Alçelik, Ayşegül

2012-11-01

In-stent restenosis (ISR) is the major limitation of percutaneous coronary stenting procedure. The elements like nickel, chromate and molybdenum are known to cause contact allergy. Hypersensitivity reaction, against these metal ions, may be one of the reasons of ISR. Cobalt chromium coronary stents, which are increasingly being used in percutaneous coronary interventions, have more nickel amount than the stainless steel stents. We aimed to investigate the association between nickel hypersensitivity reaction and ISR in patients treated with cobalt chromium coronary stents. Epicutaneous patch tests for nickel were applied to 31 patients who had undergone elective cobalt chromium coronary stent implantation and had ISR in control angiogram. Thirty patients, without ISR, were included as the control group. Patch test results and other clinical variables were compared. There was no statistically significant difference of the mean age, sex, body mass index, rate of hypercholesterolemia, diabetes, hypertension and smoking between the patients with and without ISR. All other lesion characteristics were similar in the 2 groups. According to the patch test results, 7 patients had nickel contact allergy. All of these patients were in the ISR group, which was statistically significant (p<0.006). Patients treated with cobalt chromium coronary stents and had ISR were found to have significantly more nickel allergy than the control group. Nickel allergy may play role in restenosis pathophysiology.

Serial Versus Direct Dilation of Small Diameter Stents Results in a More Predictable and Complete Intentional Transcatheter Stent Fracture: A PICES Bench Testing Study.

PubMed

Crystal, Matthew A; Morgan, Gareth J; Danon, Saar; Gray, Robert G; Gruenstein, Daniel H; Gordon, Brent M; Goldstein, Bryan H

2018-01-01

Balloon-expandable stents, implanted in infants and children with congenital heart disease (CHD), often require redilation to match somatic growth. Small diameter stents may eventually require longitudinal surgical transection to prevent iatrogenic vascular stenosis. Intentional transcatheter stent fracture (TSF) is an emerging alternative approach to stent transection, but little is known about the optimal stent substrate and best protocol to improve the likelihood of successful TSF. Bench testing was performed with a stent dilation protocol. After recording baseline characteristics, stents were serially or directly dilated using ultra-high-pressure balloons (UHPB) until fracture occurred or further stent dilation was not possible. Stent characteristics recorded were as follows: cell design, metallurgy, mechanism, and uniformity of fracture. Stents tested included bare-metal coronary stents, premounted small diameter stents, and ePTFE-covered small diameter premounted stents. Ninety-four stents representing 9 distinct models were maximally dilated, with 80 (85%) demonstrating evidence of fracture. Comprehensive fracture details were recorded in 64 stents: linear and complete in 34/64 stents (53.1%), linear and incomplete in 9/64 stents (14.1%), transverse/complex and complete in 6/64 stents (9.4%), and transverse/complex and incomplete in 15/64 stents (23.4%). Stent fracture was not accomplished in some stent models secondary to significant shortening, i.e., "napkin-ring" formation. Serial dilation resulted in evidence of fracture in 62/67 (92.5%) stents compared with 18/27 (66.7%) stents in the direct dilation group (p = 0.003). Intentional TSF is feasible in an ex vivo model. Serial dilation more reliably expanded the stent and allowed for ultimate stent fracture, whereas direct large diameter dilation of stents was more likely to generate a "napkin-ring" configuration, which may be more resistant to fracture. In vivo animal and human testing is necessary to

The impact of precise robotic lesion length measurement on stent length selection: ramifications for stent savings.

PubMed

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.

Hemodynamics of 8 different configurations of stenting for bifurcation aneurysms.

PubMed

Kono, K; Terada, T

2013-10-01

SACE is performed for complex aneurysms. There are several configurations of stent placement for bifurcation aneurysms. We investigated hemodynamics among 8 different configurations of stent placement, which may relate to the recanalization rate. We created a silicone block model of a patient-specific asymmetric bifurcation aneurysm. Enterprise closed-cell stents were deployed in the model as various configurations. 3D images of these stents were obtained by micro-CT. We performed CFD simulations for a no-stent model and 8 stent models: a single stent from a proximal vessel to a right or left distal vessel, a horizontal stent, a kissing-Y stent with a uniformly narrowed structure, a nonoverlapping-Y stent, a virtual-Y stent with no narrowed structure (fusion of 2 single stents), and 2 different crossing-Y stents with a focally narrowed structure. Hemodynamic parameters were evaluated. Cycle-averaged velocity and WSS in the aneurysm were reduced because of stent placement in the following order: single stent (19% reduction in cycle-averaged velocity) < nonoverlapping-Y stent (29%) < virtual-Y stent (32%) < horizontal stent (39%) < kissing-Y stent (48%) < crossing-Y stent (54%). Kissing- and crossing-Y stents redirected impingement flow into the distal vessels because of lowered porosity of stents due to narrowed structures. Among 8 different configurations of stent placement, kissing- and crossing-Y stents showed the strongest reduction in flow velocity in the aneurysm because of lowered porosity of stents and redirection of impingement flow. This may be a desirable reconstruction of flow hemodynamics and may decrease recanalization rates in SACE.

Risk factors for lower urinary tract infection and bacterial stent colonization in patients with a double J ureteral stent.

PubMed

Akay, Ali Ferruh; Aflay, Uğur; Gedik, Abdullah; Sahin, Hayrettin; Bircan, Mehmet Kamuran

2007-01-01

We investigated the potential risk factors for lower urinary tract infection and bacterial stent colonization in patients with double-J stents. A total of 195 double-J stents from 190 patients (95 men and 95 women, mean age 40.22 years) were examined. In all patients, prophylactic antimicrobial therapy was administered at the time of stenting. The stents and urine samples were removed aseptically and the proximal and distal tip segments of the stents were obtained. Three culture specimens were obtained from each stent segment and urine sample. Chi-square tests, odds ratio, and relative risk were used for the statistical analysis. Bacterial colonies were found in 24% (47 of 190) of the urine samples, 31% (61 of 195) of the proximal stent segments, and 34% (67 of 195) of the distal stent segments. Of the pathogens identified, Escherichia coli (34 of 47) was the most common. Diabetes mellitus (P < 0.01), chronic renal failure (P < 0.001), and pregnancy (P < 0.01) were found to be risk factors for lower urinary tract infection in patients with stents. An increased stent colonization rate was associated with implantation time, age, and female sex, but these were not statistically significant for lower urinary tract infection Diabetes mellitus, chronic renal failure, and pregnancy are associated with a higher risk of lower urinary tract infection. Therefore, patients in these categories should be monitored carefully for infectious complications.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopera, Jorge E.; Alvarez, Oscar A.; Perdigao, Joseph

2003-09-15

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

Are Carotid Stent Fractures Clinically Significant?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Toca, Manuel; Rodriguez, Heron E.; Naughton, Peter A.

2012-04-15

Purpose: Late stent fatigue is a known complication after carotid artery stenting (CAS) for cervical carotid occlusive disease. The purpose of this study was to determine the prevalence and clinical significance of carotid stent fractures. Materials and Methods: A single-center retrospective review of 253 carotid bifurcation lesions treated with CAS and mechanical embolic protection from April 2001 to December 2009 was performed. Stent integrity was analyzed by two independent observers using multiplanar cervical plain radiographs with fractures classified into the following types: type I = single strut fracture; type II = multiple strut fractures; type III = transverse fracture; andmore » type IV = transverse fracture with dislocation. Mean follow-up was 32 months. Results: Follow-up imaging was completed on 106 self-expanding nitinol stents (26 closed-cell and 80 open-cell stents). Eight fractures (7.5%) were detected (type I n = 1, type II n = 6, and type III n = 1). Seven fractures were found in open-cell stents (Precise n = 3, ViVEXX n = 2, and Acculink n = 2), and 1 fracture was found in a closed-cell stent (Xact n = 1) (p = 0.67). Only a previous history of external beam neck irradiation was associated with fractures (p = 0.048). No associated clinical sequelae were observed among the patients with fractures, and only 1 patient had an associated significant restenosis ({>=}80%) requiring reintervention. Conclusions: Late stent fatigue after CAS is an uncommon event and rarely clinically relevant. Although cell design does not appear to influence the occurrence of fractures, lesion characteristics may be associated risk factors.« less

Endoscopic biliary stent insertion through specialized duodenal stent for combined malignant biliary and duodenal obstruction facilitated by stent or PTBD guidance.

PubMed

Lee, Jong Jin; Hyun, Jong Jin; Choe, Jung Wan; Lee, Dong-Won; Kim, Seung Young; Jung, Sung Woo; Jung, Young Kul; Koo, Ja Seol; Yim, Hyung Joon; Lee, Sang Woo

2017-11-01

Endoscopic stenting for combined malignant biliary and duodenal obstruction is technically demanding. However, this procedure can be facilitated when there is guidance from previously inserted stent or PTBD tube. This study aimed to evaluate the feasibility and clinical success rate of endoscopic placement of biliary self-expandable metal stent (SEMS) through duodenal SEMS in patients with combined biliary and duodenal obstruction due to inoperable or metastatic periampullary malignancy. A total of 12 patients with combined malignant biliary and duodenal stricture underwent insertion of biliary SEMS through the mesh of specialized duodenal SEMS from July 2012 to October 2016. Technical and clinical success rate, adverse events and survival after completion of SEMS insertion were evaluated. The duodenal strictures were located in the first portion of the duodenum in four patients (Type I), in the second portion in three patients (Type II), and in the third portion in five patients (Type III). Technical success rate of combined metallic stenting was 91.7%. Insertion of biliary SEMS was guided by previously inserted biliary SEMS in nine patients, plastic stent in one patient, and PTBD in two patients. Clinical success rate was 90.9%. There were no early adverse events after the procedure. Mean survival period after combined metallic stenting was 91.9 days (range: 15-245 days). Endoscopic placement of biliary SEMS through duodenal SEMS is feasible with high success rates and relatively easy when there is guidance. This method can be a good alternative for palliation in patients with combined biliary and duodenal obstruction.

First Experience of Inserting a Metallic Mesh Stent (Uventa Stent) in Malignant Ureteral Obstruction in Iran.

PubMed

Ghaed, Mohammad Ali; Daniali, Maziar; Ebrahimian, Mohammad

2018-05-03

Malignant ureteral obstruction is usually caused by an extrinsic compression including intra-abdominal cancers. One of the treatment modalities decompressing the obstruction is applying stent to open the ureter. Metallic Stent is an effective instrument which we used for the first time in Iran in our patient who had a metastatic colon cancerwith a single kidney and we used a Novel, Double-Layered, Coated, Self-expandable Metallic Mesh Stent (Uventa Stent) to keep the ureter open. After six months of follow up with ureteroscopy, there was no obstruction any more.

[The bioresorbable coronary stent: a revolution].

PubMed

Koegler, Flora; De Benedetti, Edoardo

2013-04-10

Coronary angioplasty has undergone several technological revolutions: starting with balloon angioplasty, then with bare metal stent and finally with drug eluting stent (DES), this technique is now mature. However, once we thought the problem of instent restenosis solved with DES, new concerns arise with late and very late stent thrombosis. Should we therefore proscribe DES? How long should be the duration of dual antiplatelet therapy? And how should we manage the patients who need a surgery and are at high risk of bleeding? Are bioresorbable stents the final solution with their initial mechanical properties, then with their drug eluting effect against intra-stent restenosis, and finally with their complete resorption which leaves the artery free of any foreign material?

Evaluation of a bifurcation drug-eluting stent system versus provisional T-stenting in a perfused synthetic coronary artery model.

PubMed

Rizik, David G; Klag, Joseph M; Tenaglia, Alan; Hatten, Thomas R; Barnhart, Marianne; Warnack, Boris

2009-12-01

Provisional T-stenting is a widely used strategy for the treatment of coronary artery bifurcation lesions. However, the use of conventional stents in this setting is limited by multiple factors; this includes technical considerations such as wire wrap when accessing the involved vessel, and stent overlap at or near the carina of the lesion. In addition, current slotted tube stent technology tends to be associated with gaps in the coverage of the side branch ostium, which may result in restenosis in that segment of the lesion. The Pathfinder device, now more commonly referred to as the Xience Side Branch Access System (Xience SBA) is a drug-eluting stent (DES) designed specifically to assist in the treatment of bifurcation lesions by allowing wire access into the side branch, irrespective of the treatment strategy to be employed. The Xience SBA drug-eluting stent was compared with the standard Vision coronary stent system using a provisional T-stenting strategy in a perfused synthetic model of the coronary vasculature with side branch angulations of 30 degrees , 50 degrees , 70 degrees , and 90 degrees . Stent delivery was performed under fluoroscopic guidance. Following the procedure, high-resolution 2D Faxitron imaging was used to evaluate deployment accuracy of the side branch stent relative to the main branch stent. Deployment of the Xience SBA was accomplished in the same total time as the standard stents in a provisional T-stenting approach (14.9 vs. 14.6 minutes). However, the time required to achieve stent deployment in the main branch was less with the Xience SBA (4.0 vs. 6.6 minutes), and as a result, total contrast usage (49.4 vs. 69.4 cm(3)) and fluoroscopy time (5.1 vs. 6.2 minutes) was lower. Additionally, the Xience SBA had a lower incidence of wire wrap (22% vs. 89%) and less distal protrusion of the side branch stent into the main branch (0.54 vs. 1.21 mm). Significant gaps in ostial side branch coverage were not seen in either group. The Xience

Comparison of diamond-like carbon-coated nitinol stents with or without polyethylene glycol grafting and uncoated nitinol stents in a canine iliac artery model

PubMed Central

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

The role of stents in the treatment of congenital heart disease: Current status and future perspectives

PubMed Central

Peters, Bjoern; Ewert, Peter; Berger, Felix

2009-01-01

Intravascular or intracardiac stenoses occur in many forms of congenital heart disease (CHD). Therefore, the implantation of stents has become an accepted interventional procedure for stenotic lesions in pediatric cardiology. Furthermore, stents are know to be used to exclude vessel aneurysm or to ensure patency of existing or newly created intracardiac communications. With the further refinement of the first generation of devices, a variety of “modern” stents with different design characteristics have evolved. Despite the tremendous technical improvement over the last 20 years, the “ideal stent” has not yet been developed. Therefore, the pediatric interventionalist has to decide which stent is suitable for each lesion. On this basis, currently available stents are discussed in regard to their advantages and disadvantages for common application in CHD. New concepts and designs developed to overcome some of the existing problems, like the failure of adaptation to somatic growth, are presented. Thus, in the future, biodegradable or growth stents might replace the currently used generation of stents. This might truly lead to widening indications for the use of stents in the treatment of CHD. PMID:20300265

Endobiliary Stent Position Changes during External-beam Radiotherapy

PubMed Central

Chu, Kwun-Ye; Eccles, Cynthia L.; Brunner, Thomas B.

2015-01-01

Purpose Endobiliary stents can be used as surrogates for pancreatic localization when using cone-beam computed tomography (CBCT) during external-beam radiotherapy (EBRT). This work reports on interfraction stent position changes during EBRT for locally advanced pancreatic cancer (LAPC). Materials and Methods Six patients with endobiliary stents who underwent EBRT for LAPC were assessed. Measurements from the most superior aspect of the stent (sup stent) and the most inferior aspect of the stent (inf stent) to the most inferior, posterior aspect of the L1 vertebra central spinous process were determined from daily treatment CBCTs and compared with those determined from the planning computed tomography (CT) scan. Changes in stent-L1 measurements were interpreted as changes in relative stent position. Results Three patients showed mean interfraction stent position changes of ≥1 cm when treatment measurements were compared with planning measurements. The sup stent for patient A moved to the right (2.66 ± 2.77 cm) and inferiorly (3.0 ± 3.12 cm), and the inf stent moved to the right (1.92 ± 2.02 cm) inferiorly (3.23 ± 3.34 cm) and posteriorly (1.41 ± 1.43 cm). The inf stent for patient B moved superiorly (2.23 ± 0.49 cm) and posteriorly (1.72 ± 0.59 cm). The sup and inf stent for patient F moved inferiorly (0.98 ± 0.35 cm and 1.21 ± 0.38 cm, respectively). The remaining three patients C, D, and E showed interfraction position changes of <1 cm. Conclusion Endobiliary stent migration and deformation were observed in a small subset of patients. Further investigation is required before confirming their use as surrogates for LAPC target localization during image-guided EBRT. PMID:26090069

Gianturco-Rösch Z stents in tracheobronchial stenoses.

PubMed

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.

Enhanced bioactivity of Mg-Nd-Zn-Zr alloy achieved with nanoscale MgF2 surface for vascular stent application.

PubMed

Mao, Lin; Shen, Li; Chen, Jiahui; Wu, Yu; Kwak, Minsuk; Lu, Yao; Xue, Qiong; Pei, Jia; Zhang, Lei; Yuan, Guangyin; Fan, Rong; Ge, Junbo; Ding, Wenjiang

2015-03-11

Magnesium (Mg) alloys have revolutionized the application of temporary load-bearing implants as they meet both engineering and medical requirements. However, rapid degradation of Mg alloys under physiological conditions remains the major obstacle hindering the wider use of Mg-based implants. Here we developed a simple method of preparing a nanoscale MgF2 film on Mg-Nd-Zn-Zr (denoted as JDBM) alloy, aiming to reduce the corrosion rate as well as improve the biological response. The corrosion rate of JDBM alloy exposed to artificial plasma is reduced by ∼20% from 0.337 ± 0.021 to 0.269 ± 0.043 mm·y(-1) due to the protective effect of the MgF2 film with a uniform and dense physical structure. The in vitro cytocompatibility test of MgF2-coated JDBM using human umbilical vein endothelial cells indicates enhanced viability, growth, and proliferation as compared to the naked substrate, and the MgF2 film with a nanoscale flakelike feature of ∼200-300 nm presents a much more favorable environment for endothelial cell adhesion, proliferation, and alignment. Furthermore, the animal experiment via implantation of MgF2-coated JDBM stent to rabbit abdominal aorta confirms excellent tissue compatibility of the well re-endothelialized stent with no sign of thrombogenesis and restenosis in the stented vessel.

Carotid artery stents on CT angiography: in vitro comparison of different stent designs and sizes using 16-, 64- and 320-row CT scanners.

PubMed

Lettau, Michael; Kotter, Elmar; Bendszus, Martin; Hähnel, Stefan

2014-10-01

CT angiography (CTA) is an increasingly used method for evaluation of stented vessel segments. Our aim was to compare the appearance of different carotid artery stents in vitro on CTA using different CT scanners. Of particular interest was the measurement of artificial lumen narrowing (ALN) caused by the stent material within the stented vessel segment to determine whether CTA can be used to detect in-stent restenosis. CTA appearances of 16 carotid artery stents of different designs and sizes (4.0 to 11.0 mm) were investigated in vitro. CTA was performed using 16-, 64- and 320-row CT scanners. For each stent, artificial lumen narrowing (ALN) was calculated. ALN ranged from 18.77% to 59.86%. ALN in different stents differed significantly. In most stents, ALN decreased with increasing stent diameter. In all but one stents, ALN using sharp image kernels was significantly lower than ALN using medium image kernels. Considering all stents, ALN did not significantly differ using different CT scanners or imaging protocols. CTA evaluation of vessel patency after stent placement is possible, but is considerably impaired by ALN. Investigators should be informed about the method of choice for every stent and stent manufacturers should be aware of potential artifacts caused by their stents during noninvasive diagnostic methods such as CTA. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Recent Advances in Gastrointestinal Stent Development

PubMed Central

Park, Jin-Seok; Jeong, Seok

2015-01-01

Endoscopic stenting is increasingly being used in the management of gastrointestinal luminal obstruction, and has become the current treatment of choice for the palliation of blockage caused by malignant or benign growths. A variety of stents have been developed to enhance the efficacy of the procedure, and improvements are ongoing. In this article, we review the history of, and recent advances in, gastrointestinal stenting. We describe the rationale behind the design as well as the resulting outcome for each stent type. PMID:26064820

Ureteral Stents: Impact on Quality of Life.

PubMed

Ucuzal, Meral; Serçe, Perihan

Ureteral stents have an indispensable place in urology, and indications for their use are increasing. However, stents can affect their users' quality of life negatively because of complications and adverse effects. This descriptive research aimed to determine the effect of ureteral stenting on quality of life. The study sample consisted of 75 patients. Data were collected using a questionnaire form, the SF-36 Quality of Life Scale, and the International Prostate Symptom Score. Patients were interviewed twice (before stenting and 1 month after stenting). The data were analyzed with descriptive statistics methods. This research determined that patients with ureteral stents had increased lower urinary tract symptoms and significantly reduced quality of life.

Nitinol Esophageal Stents: New Designs and Clinical Indications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strecker, Ernst-Peter; Boos, Irene; Vetter, Sylvia

1996-11-15

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 stentmore » 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.« less

Endotracheal nitinol stents: lessons from the learning curve.

PubMed

Siegel, Bianca; Bent, John P; Ward, Robert F

2013-04-01

To reflect on lessons learned placing endotracheal nitinol stents in children. Case series with chart review. Tertiary care children's hospital. All children who underwent nitinol cervical tracheal stenting were included. Records were carefully reviewed for intraoperative and postoperative complications, management choices, outcomes, and factors that influenced results. Between 1999 and 2011, 7 children underwent 13 stent placements. Median follow-up was 5 years (range, 1-12 years). Six patients underwent stenting as a salvage procedure following open attempts at airway reconstruction. Four patients remain decannulated with their stent in place (median follow-up 7 years). The fifth patient had his stent removed endoscopically after 50 days because it became apparent that his obstruction was primarily laryngeal. The sixth child had his stent removed via a tracheal fissure after 14 months because of recalcitrant subglottic inflammation at the superior stent border. The seventh patient was decannulated for over 2 years but ultimately required tracheotomy replacement because of stenosis with the stent lumen. Complications included stent migration (23%), restenosis (29%), edema (29%), and granulation (57%). Endotracheal nitinol stents provide a realistic opportunity for decannulation in children for whom other options have failed but should be reserved only as a salvage procedure in severely complicated airways. Our experience has taught valuable lessons about stent indications, sizing, characteristics, and deployment, as well as means to avoid and manage their complications.

Hemodynamically driven stent strut design.

PubMed

Jiménez, Juan M; Davies, Peter F

2009-08-01

Stents are deployed to physically reopen stenotic regions of arteries and to restore blood flow. However, inflammation and localized stent thrombosis remain a risk for all current commercial stent designs. Computational fluid dynamics results predict that nonstreamlined stent struts deployed at the arterial surface in contact with flowing blood, regardless of the strut height, promote the creation of proximal and distal flow conditions that are characterized by flow recirculation, low flow (shear) rates, and prolonged particle residence time. Furthermore, low shear rates yield an environment less conducive for endothelialization, while local flow recirculation zones can serve as micro-reaction chambers where procoagulant and pro-inflammatory elements from the blood and vessel wall accumulate. By merging aerodynamic theory with local hemodynamic conditions we propose a streamlined stent strut design that promotes the development of a local flow field free of recirculation zones, which is predicted to inhibit thrombosis and is more conducive for endothelialization.

Enhancing Stent Effectiveness with Nanofeatures

PubMed Central

Bassous, Nicole; Cooke, John P.; Webster, Thomas J.

2016-01-01

Drug-eluting stents are an effective therapy for symptomatic arterial obstructions, substantially reducing the incidence of restenosis by suppressing the migration and proliferation of vascular smooth muscle cells into the intima. However, current drug-eluting stents also inhibit the growth of endothelial cells, which are required to cover the vascular stent to reduce an excessive inflammatory response. As a result, the endothelial lining of the lumen is not regenerated. Since the loss of this homeostatic monolayer increases the risk of thrombosis, patients with drug-eluting stents require long-term antithrombotic therapy. Thus, there is a need for improved devices with enhanced effectiveness and physiological compatibility towards endothelial cells. Current developments in nanomaterials may enhance the function of commercially available vascular devices. In particular, modified design schemes might incorporate nanopatterns or nanoparticle-eluting features that reduce restenosis and enhance re-endothelialization. The intent of this review is to discuss emerging nanotechnologies that will improve the performance of vascular stents. PMID:27826371

Effects of plaque lengths on stent surface roughness.

PubMed

Syaifudin, Achmad; Takeda, Ryo; Sasaki, Katsuhiko

2015-01-01

The physical properties of the stent surface influence the effectiveness of vascular disease treatment after stent deployment. During the expanding process, the stent acquires high-level deformation that could alter either its microstructure or the magnitude of surface roughness. This paper constructed a finite element simulation to observe the changes in surface roughness during the stenting process. Structural transient dynamic analysis was performed using ANSYS, to identify the deformation after the stent is placed in a blood vessel. Two types of bare metal stents are studied: a Palmaz type and a Sinusoidal type. The relationship between plaque length and the changes in surface roughness was investigated by utilizing three different length of plaque; plaque length longer than the stent, shorter than the stent and the same length as the stent. In order to reduce computational time, 3D cyclical and translational symmetry was implemented into the FE model. The material models used was defined as a multilinear isotropic for stent and hyperelastic for the balloon, plaque and vessel wall. The correlation between the plastic deformation and the changes in surface roughness was obtained by intermittent pure tensile test using specimen whose chemical composition was similar to that of actual stent material. As the plastic strain is achieved from FE simulation, the surface roughness can be assessed thoroughly. The study found that the plaque size relative to stent length significantly influenced the critical changes in surface roughness. It was found that the length of stent which is equal to the plaque length was preferable due to the fact that it generated only moderate change in surface roughness. This effect was less influential to the Sinusoidal stent.

Resolution of Metallic Biliary Stent Allergic Reaction After Partial Stent Removal in a Patient with Nickel Sensitivity.

PubMed

Esparaz, Anthony M; Ahmed, Muneeb

2017-07-01

Local and systemic reactions to implanted metallic devices, particularly to those containing nickel, are well documented. Metal ions are released due to exposure of the metal to blood, proteins, other body fluids, and sheer mechanical stress. Metal ions then complex with native proteins and become antigens, which can elicit hypersensitivity reactions. Another case report depicts a specific allergic complication (early stent occlusion) related to metallic biliary stent implantation. We present a case of allergic symptoms, associated with eating, in a patient who developed nickel sensitivity after biliary metal stent placement confirmed by allergic skin testing to the same metallic biliary stent placed one year earlier. Symptoms resolved following partial removal of the non-epithelialized portion of the biliary stent.

Sequential Stenting for Extensive Malignant Airway Stenosis

PubMed Central

Takahama, Makoto; Nakajima, Ryu; Kimura, Michitaka; Tei, Keiko; Yamamoto, Ryoji

2014-01-01

Purpose: Malignant airway stenosis extending from the bronchial bifurcation to the lower lobar orifice was treated with airway stenting. We herein examine the effectiveness of airway stenting for extensive malignant airway stenosis. Methods: Twelve patients with extensive malignant airway stenosis underwent placement of a silicone Dumon Y stent (Novatech, La Ciotat, France) at the tracheal bifurcation and a metallic Spiral Z-stent (Medico’s Hirata, Osaka, Japan) at either distal side of the Y stent. We retrospectively analyzed the therapeutic efficacy of the sequential placement of these silicone and metallic stents in these 12 patients. Results: The primary disease was lung cancer in eight patients, breast cancer in two patients, tracheal cancer in one patient, and thyroid cancer in one patient. The median survival period after airway stent placement was 46 days. The Hugh–Jones classification and performance status improved in nine patients after airway stenting. One patient had prolonged hemoptysis and died of respiratory tract hemorrhage 15 days after the treatment. Conclusion: Because the initial disease was advanced and aggressive, the prognosis after sequential airway stent placement was significantly poor. However, because respiratory distress decreased after the treatment in most patients, this treatment may be acceptable for selected patients with extensive malignant airway stenosis. PMID:25273272

Novel strategy of stents in thyroid mass: a case series report of managing severely dyspneic patients.

PubMed

Bhandari, Adheesh; Wang, Ying-Hao; Lv, Shi-Xu; Xia, Er-Jie; Wang, Ou-Chen

2017-01-01

Tracheal and bronchial stenosis is a life-threatening condition causing difficulty in breathing and even severe respiratory distress. The silicone tracheobronchial stents were placed using the rigid bronchoscopy into the trachea of severe dyspneic patients and they exhibited symptomatic improvement as well as a rise in the saturation of oxygen. The bronchial stents were applicable to many extensive malignant airway stenosis patients, such as those with esophageal cancer, lung cancer, and laryngeal cancer. But the effectiveness of bronchial stents for thyroid cancer is not certain. Here, we report 3 emergency patients with a thyroid mass referred to our hospital because of grade 4 dyspnea according to the American Thoracic Society shortness of breath guidelines. The main clinical symptoms were severe dyspnea and stridor. The radiographic examination and tomographic examination showed the narrowing and displacement of the trachea. To the best of our knowledge, ideal airway management for the massive thyroid mass was considered to be temporary tracheobronchial stent placement pre-operation. In our study, we applied the tracheobronchial stent to massive thyroid mass patients with dyspnea and aimed to not only improve preoperative airway obstruction but also to protect the potential airway collapse from post-operative tracheomalacia following extubation. We found that application of tracheobronchial stents may provide a new strategy to dyspneic patients with huge thyroid mass.

Novel strategy of stents in thyroid mass: a case series report of managing severely dyspneic patients

PubMed Central

Lv, Shi-xu; Xia, Er-jie; Wang, Ou-Chen

2017-01-01

Background Tracheal and bronchial stenosis is a life-threatening condition causing difficulty in breathing and even severe respiratory distress. The silicone tracheobronchial stents were placed using the rigid bronchoscopy into the trachea of severe dyspneic patients and they exhibited symptomatic improvement as well as a rise in the saturation of oxygen. The bronchial stents were applicable to many extensive malignant airway stenosis patients, such as those with esophageal cancer, lung cancer, and laryngeal cancer. But the effectiveness of bronchial stents for thyroid cancer is not certain. Case presentation Here, we report 3 emergency patients with a thyroid mass referred to our hospital because of grade 4 dyspnea according to the American Thoracic Society shortness of breath guidelines. The main clinical symptoms were severe dyspnea and stridor. The radiographic examination and tomographic examination showed the narrowing and displacement of the trachea. To the best of our knowledge, ideal airway management for the massive thyroid mass was considered to be temporary tracheobronchial stent placement pre-operation. Conclusion In our study, we applied the tracheobronchial stent to massive thyroid mass patients with dyspnea and aimed to not only improve preoperative airway obstruction but also to protect the potential airway collapse from post-operative tracheomalacia following extubation. We found that application of tracheobronchial stents may provide a new strategy to dyspneic patients with huge thyroid mass. PMID:29081662

In vivo evaluation of axial integrity of coronary stents using intravascular ultrasound: Insights on longitudinal stent deformation.

PubMed

Dvir, Danny; Kitabata, Hironori; Barbash, Israel M; Minha, Sa'ar; Badr, Salem; Loh, Joshua P; Chen, Fang; Torguson, Rebecca; Waksman, Ron

2014-09-01

To evaluate the axial integrity of different coronary stents using intravascular ultrasound (IVUS). Longitudinal stent deformation was recently reported. Consecutive patients who underwent IVUS analysis after drug-eluting stent (DES) implantation for de novo coronary lesions were evaluated. Stent length was compared with label length for calculation of absolute change and relative difference (absolute change divided by label length). A total of 233 DES utilizing five different platforms were included. The median absolute change in stent length was 0.90 mm (interquartile range [IQR] 0.48-1.39) and the relative difference was 5.24% (IQR 2.55-8.29). There was no significant difference among the groups in median absolute or relative change: Cypher 0.89 mm/3.89%, Taxus 0.88 mm/5.39%, Endeavor 1.16 mm/6.77%, Xience V 0.86 mm/5.80%, and PROMUS Element 0.79 mm/5.34% (P = 0.085, P = 0.072, respectively). Multivariate logistic regression revealed that the Cypher stent was independently correlated with a lower change in length, whereas stent label length and deployment pressure were correlated with higher absolute change. The axial integrity of DES platforms examined in vivo was high, with only mild changes in stent length after implantation. While there are differences between first- and second-generation DES, axial integrity among second-generation DES was similar. © 2013 Wiley Periodicals, Inc.

Efficacy of different types of self-expandable stents in carotid artery stenting for carotid bifurcation stenosis.

PubMed

Liu, Ya-min; Qin, Hao; Zhang, Bo; Wang, Yu-jing; Feng, Jun; Wu, Xiang

2016-02-01

Both open and closed loop self-expandable stents were used in carotid artery stenting (CAS) for carotid bifurcation stenosis. We sought to compare the efficacy of two types of stents in CAS. The data of 212 patients treated with CAS (42 and 170 cases implanted with closed and open loop stents, respectively) for carotid bifurcation stenosis and distal filtration protection devices were retrospectively analyzed. Between closed and open loop stents, there were no significant differences in hospitalization duration, NIHSS score before and after the treatment, stenosis at 12th month, and cumulative incidence of primary endpoint events within 30 days or from the 31st day to the 12th month; while there were significant differences in hemodynamic changes and rate of difficulty in recycling distal filtration protection devices. Use of open vs. closed loop stents for carotid bifurcation stenosis seems to be associated with similar incidence of complications, except for greater rate of hemodynamic changes and lower rate of difficulty in recycling the distal filtration protection devices.

Wing-shaped plastic stents vs. self-expandable metal stents for palliative drainage of malignant distal biliary obstruction: a randomized multicenter study.

PubMed

Schmidt, Arthur; Riecken, Bettina; Rische, Susanne; Klinger, Christoph; Jakobs, Ralf; Bechtler, Matthias; Kähler, Georg; Dormann, Arno; Caca, Karel

2015-05-01

Previous studies have shown superior patency rates for self-expandable metal stents (SEMS) compared with plastic stents in patients with malignant biliary obstruction. The aim of this study was to compare stent patency, patient survival, and complication rates between a newly designed, wing-shaped, plastic stent and SEMSs in patients with unresectable, malignant, distal, biliary obstruction. A randomized, multicenter trial was conducted at four tertiary care centers in Germany. A total of 37 patients underwent randomization between March 2010 and January 2013. Patients underwent endoscopic retrograde cholangiography with insertion of either a wing-shaped, plastic stent without lumen or an SEMS.  Stent failure occurred in 10/16 patients (62.5 %) in the winged-stent group vs. 4/18 patients (22.2 %) in the SEMS group (P = 0.034). The median time to stent failure was 51 days (range 2 - 92 days) for the winged stent and 80 days (range 28 - 266 days) for the SEMS (P = 0.002). Early stent failure (< 8 weeks after placement) occurred in 8 patients (50 %) vs. 2 patients (11.1 %), respectively (P = 0.022). After obtaining the results from this interim analysis, the study was discontinued because of safety concerns. The frequency of stent failure was significantly higher in the winged-stent group compared with the SEMS group. A high incidence of early stent failure within 8 weeks was observed in the winged-stent group. Thus, the winged, plastic stent without central lumen may not be appropriate for mid or long term drainage of malignant biliary obstruction. Study registration ClinicalTrials.gov (NCT01063634). © Georg Thieme Verlag KG Stuttgart · New York.

[How to prevent tissue overgrowth and incrustation of metal stents in the urinary tract in patients with pelvic malignancy] b ].

PubMed

Marković, Z; Masulović, D; Markovic, B; Anojcić, P; Mladenović, A

2009-01-01

At the current level of stent application in urology each irreversible urostasis contraindicated for surgical therapy implies consideration of indications for metal stent insertion. Stent incrustation which leads directly into a new uroobstruction is a characteristic complication of this method. Available experience in different uroobstructive conditions has shown that very different clinical aspects of stent usage may directly determine the possibility of their incrustation. Stent incrustation may occur in the early postprocedural course or several months later. After that, prevention of stent incrustation starts with postprocedural evaluation, selection of the stent type, and it is subsequently continued by insertion technique and lasts practically permanently after the insertion (infection control, promotion of diuresis and maintenance of normal urodynamics). Authors present own experianse in clinical aplication of metal stents in uroradiology strictures for period of last 15 years.

Fabrication of balloon-expandable self-lock drug-eluting polycaprolactone stents using micro-injection molding and spray coating techniques.

PubMed

Liu, Shih-Jung; Chiang, Fu-Jun; Hsiao, Chao-Ying; Kau, Yi-Chuan; Liu, Kuo-Sheng

2010-10-01

The purpose of this report was to develop novel balloon-expandable self-lock drug-eluting poly(ε-caprolactone) stents. To fabricate the biodegradable stents, polycaprolactone (PCL) components were first fabricated by a lab-scale micro-injection molded machine. They were then assembled and hot-spot welded into mesh-like stents of 3 and 5 mm in diameters. A special geometry of the components was designed to self-lock the assembled stents and to resist the external pressure of the blood vessels after being expanded by balloons. Characterization of the biodegradable PCL stents was carried out. PCL stents exhibited comparable mechanical property to that of metallic stents. No significant collapse pressure reduction and weight loss of the stents were observed after being submerged in PBS for 12 weeks. In addition, the developed stent was coated with paclitaxel by a spray coating technique and the release characteristic of the drug was determined by an in vitro elution method. The high-performance liquid chromatography analysis showed that the biodegradable stents could release a high concentration of paclitaxel for more than 60 days. By adopting the novel techniques, we will be able to fabricate biodegradable drug-eluting PCL stents of different sizes for various cardiovascular applications.

Carotid artery stenting: current and emerging options

PubMed Central

Morr, Simon; Lin, Ning; Siddiqui, Adnan H

2014-01-01

Carotid artery stenting technologies are rapidly evolving. Options for endovascular surgeons and interventionists who treat occlusive carotid disease continue to expand. We here present an update and overview of carotid stenting devices. Evidence supporting carotid stenting includes randomized controlled trials that compare endovascular stenting to open surgical endarterectomy. Carotid technologies addressed include the carotid stents themselves as well as adjunct neuroprotective devices. Aspects of stent technology include bare-metal versus covered stents, stent tapering, and free-cell area. Drug-eluting and cutting balloon indications are described. Embolization protection options and new direct carotid access strategies are reviewed. Adjunct technologies, such as intravascular ultrasound imaging and risk stratification algorithms, are discussed. Bare-metal and covered stents provide unique advantages and disadvantages. Stent tapering may allow for a more fitted contour to the caliber decrement between the common carotid and internal carotid arteries but also introduces new technical challenges. Studies regarding free-cell area are conflicting with respect to benefits and associated risk; clinical relevance of associated adverse effects associated with either type is unclear. Embolization protection strategies include distal filter protection and flow reversal. Though flow reversal was initially met with some skepticism, it has gained wider acceptance and may provide the advantage of not crossing the carotid lesion before protection is established. New direct carotid access techniques address difficult anatomy and incorporate sophisticated flow-reversal embolization protection techniques. Carotid stenting is a new and exciting field with rapidly advancing technologies. Embolization protection, low-risk deployment, and lesion assessment and stratification are active areas of research. Ample room remains for further innovations and developments. PMID:25349483

Semi-Automatic Electronic Stent Register: a novel approach to preventing ureteric stents lost to follow up.

PubMed

Macneil, James W H; Michail, Peter; Patel, Manish I; Ashbourne, Julie; Bariol, Simon V; Ende, David A; Hossack, Tania A; Lau, Howard; Wang, Audrey C; Brooks, Andrew J

2017-10-01

Ureteric stents are indispensable tools in modern urology; however, the risk of them not being followed-up once inserted poses medical and medico-legal risks. Stent registers are a common solution to mitigate this risk; however, manual registers are logistically challenging, especially for busy units. Western Sydney Local Health District developed a novel Semi-Automatic Electronic Stent Register (SAESR) utilizing billing information to track stent insertions. To determine the utility of this system, an audit was conducted comparing the 6 months before the introduction of the register to the first 6 months of the register. In the first 6 months of the register, 457 stents were inserted. At the time of writing, two of these are severely delayed for removal, representing a rate of 0.4%. In the 6 months immediately preceding the introduction of the register, 497 stents were inserted, and six were either missed completely or severely delayed in their removal, representing a rate of 1.2%. A non-inferiority analysis found this to be no worse than the results achieved before the introduction of the register. The SAESR allowed us to improve upon our better than expected rate of stents lost to follow up or severely delayed. We demonstrated non-inferiority in the rate of lost or severely delayed stents, and a number of other advantages including savings in personnel costs. The semi-automatic register represents an effective way of reducing the risk associated with a common urological procedure. We believe that this methodology could be implemented elsewhere. © 2017 Royal Australasian College of Surgeons.

Finite Element Analysis of the Implantation Process of Overlapping Stents

PubMed Central

Xu, Jiang; Yang, Jie; Sohrabi, Salman; Zhou, Yihua; Liu, Yaling

2017-01-01

Overlapping stents are widely used in vascular stent surgeries. However, the rate of stent fractures (SF) and in-stent restenosis (ISR) after using overlapping stents is higher than that of single stent implantations. Published studies investigating the nature of overlapping stents rely primarily on medical images, which can only reveal the effect of the surgery without providing insights into how stent overlap influences the implantation process. In this paper, a finite element analysis of the overlapping stent implantation process was performed to study the interaction between overlapping stents. Four different cases, based on three typical stent overlap modes and two classical balloons, were investigated. The results showed that overlapping contact patterns among struts were edge-to-edge, edge-to-surface, and noncontact. These were mainly induced by the nonuniform deformation of the stent in the radial direction and stent tubular structures. Meanwhile, the results also revealed that the contact pressure was concentrated in the edge of overlapping struts. During the stent overlap process, the contact pattern was primarily edge-to-edge contact at the beginning and edge-to-surface contact as the contact pressure increased. The interactions between overlapping stents suggest that the failure of overlapping stents frequently occurs along stent edges, which agrees with the previous experimental research regarding the safety of overlapping stents. This paper also provides a fundamental understanding of the mechanical properties of overlapping stents. PMID:28690712

Prevention of stent thrombosis: challenges and solutions

PubMed Central

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

Development of asymmetric stent for treatment of eccentric plaque.

PubMed

Syaifudin, Achmad; Takeda, Ryo; Sasaki, Katsuhiko

2018-01-01

The selection of stent and balloon type is decisive in the stenting process. In the treatment of an eccentric plaque obstruction, a symmetric expansion from stent dilatation generates nonuniform stress distribution, which may aggravate fibrous cap prone to rupture. This paper developed a new stent design to treat eccentric plaque using structural transient dynamic analysis in ANSYS. A non-symmetric structural geometry of stent is generated to obtain reasonable stress distribution safe for the arterial layer surrounding the stent. To derive the novel structural geometry, a Sinusoidal stent type is modified by varying struts length and width, adding bridges, and varying curvature width of struts. An end ring of stent struts was also modified to eliminate dogboning phenomenon and to reduce the Ectropion angle. Two balloon types were used to deploy the stent, an ordinary cylindrical and offset balloon. Positive modification results were used to construct the final non-symmetric stent design, called an Asymmetric stent. Analyses of the deformation characteristics, changes in surface roughness and induced stresses within intact arterial layer were subsequently examined. Interaction between the stent and vessel wall was implemented by means of changes in surface roughness and stress distribution analyses. The Palmaz and the Sinusoidal stent were used for a comparative study. This study indicated that the Asymmetric stent types reduced the central radial recoiling and the dogboning phenomenon. In terms of changes in surface roughness and induced stresses, the Asymmetric stent has a comparable effect with that of the Sinusoidal stent. In addition, it could enhance the distribution of surface roughening as expanded by an offset balloon.

21 CFR 876.4620 - Ureteral stent.

Code of Federal Regulations, 2010 CFR

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...

A novel, ring-connected stent versus conventional GI stents: comparative study of physical properties and migration rates in a canine colon obstruction model.

PubMed

Park, Hong Suk; Choo, In Wook; Seo, Soowon; Hyun, Dongho; Lim, Sooyoun; Kim, Jae J; Hong, Saet-Byul; Min, Byung-Hoon; Do, Young Soo; Choo, Sung Wook; Shin, Sung Wook; Park, Kwang Bo; Cho, Sung Ki

2015-01-01

Migration of stents is one of the most common adverse events in covered stent placement in GI tract obstruction. To compare physical property and migration rates in a canine colon obstruction model among a novel stent and conventional stents. Comparative physical test and animal study. Medical device testing laboratory and animal laboratory. Mongrel dogs (N=26). Surgical colon obstruction followed by placement of a novel (n=13) or conventional (n=13) stent. Physical properties, migration, and adverse events. The novel stent showed better flexibility, as in a physical test of longitudinal compressibility and axial force, than did conventional stents, and it withstood the fatigue test for 10 days. In terms of radial force and tensile strength, the novel stent showed the same or better results than conventional stents. In a canine colon obstruction model, the migration rate of a novel stent was significantly lower than that of a conventional stent (2/13, 15.4% vs 8/13, 61.5%; P=.008). Animal study of limited size. The novel, ring-connected stent is more flexible and more resistant to migration than the conventional stents. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Prospective analysis of a complete retrograde ureteroscopic technique with holmium laser stent cutting for management of encrusted ureteral stents.

PubMed

Thomas, Alexandre; Cloutier, Jonathan; Villa, Luca; Letendre, Julien; Ploumidis, Achilles; Traxer, Olivier

2017-03-14

To propose and evaluate a new endoscopic technique using only a retrograde ureteroscopic approach for the removal of heavily encrusted ureteral stents. Data from 51 consecutive patients with encrusted and retained ureteral stents were prospectively collected. Description of the successive steps of surgery is detailed. The Holmium-YAG laser properties offer the opportunity for fragmentation of stent-attached encrustation and the ability to cut the stent itself. Reducing the length of the stent is critical to creating space in the ureter and to allow free access for ureteroscopes or ureteral access sheath placement. The primary outcome of this study was the feasibility and the safety of this retrograde intra-renal approach. Some factors of encrustation and outcomes are also discussed in comparison with lithotripsy, percutaneous, laparoscopic, open surgery or a combination of these techniques. The removal of the encrusted stent was possible with only this retrograde technique in 98% of patients. The transection of the encrusted stent with the Holmium-YAG laser was useful in 71% of the patients. Mean operative time was 110 minutes and mean hospital stay was 2.33 days. Postoperative complications were mainly non-obstructive pyelonephritis (10%). The most significant predictor of this life threatened complication was the presence of struvite stones with the encrusted stent (p=0,018). Contrariwise, operative time, BMI, gender and encrustation rate were not associated with postoperative pyelonephritis. Cystine stone disease or pregnancy both led to faster stent encrustation. Retrograde ureteroscopic surgery is efficient and safe for removing retained stents and associated stone burdens. The Holmium-YAG laser is essential to perform the encrustation removal and sectioning of the stent.

Functional Self-Expandable Metal Stents in Biliary Obstruction

PubMed Central

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

Coronary artery stent (image)

MedlinePlus

... with a balloon catheter and expands when the balloon is inflated. The stent is then left there to help keep the artery open. ... with a balloon catheter and expands when the balloon is inflated. The stent is then left there to help keep the artery open.

Y-configuration double-stent-assisted coiling using two closed-cell stents for wide-neck basilar tip aneurysms.

PubMed

Jeon, Pyoung; Kim, Byung Moon; Kim, Dong Joon; Kim, Dong I K; Park, Keun Young

2014-09-01

This study aimed to evaluate clinical and angiographic outcomes of Y-configuration double-stent-assisted (Y-stent) coiling using two closed-cell stents for wide-necked basilar tip aneurysm (BTA). A total of 25 patients underwent Y-stent coiling using two closed-cell stents as a first-time treatment in 18 (3 ruptured) BTAs, retreatment in 2 BTAs and as a third treatment in 5 wide-necked BTAs. Clinical and angiographic outcomes were evaluated retrospectively. Treatment-related complications were three (12.0 %) thromboembolic infarctions due to two acute in-stent thromboses and one embolism. Twenty-two (88 %) patients had favorable outcomes (modified Rankin scale score [mRS], 0-2) during the follow-up period (mean, 30 months; range, 6-54 months). Two patients died: one from initial subarachnoid hemorrhage and the other from intracerebral hemorrhage due to underlying Moyamoya disease. Post-treatment angiograms showed complete occlusion in nine aneurysms, residual neck in 11 aneurysms and residual sac in five aneurysms. Follow-up angiograms were available at least once between 5 to 34 months (mean, 16 months) in 21 patients. Nineteen patients showed improved or stable states (complete occlusion, n = 17; residual neck, n = 2). Major recurrences occurred in two BTAs (9.5 %). Those two major recurrent aneurysms had been large-sized aneurysms at the initial coiling procedure. Both showed not only coil compaction but also progressive growth to giant-sized aneurysms and intra-aneurysmal thrombus formation at the Y-stent coiling as a third-time treatment. Y-stent coiling using two closed-cell stents is a safe and durable treatment option for wide-necked BTA, but may have limited efficacy for large/giant sized and thrombosed aneurysms.

The PARAGON stent study: a randomized trial of a new martensitic nitinol stent versus the Palmaz-Schatz stent for treatment of complex native coronary arterial lesions.

PubMed

Holmes, D R; Lansky, A; Kuntz, R; Bell, M R; Buchbinder, M; Fortuna, R; O'Shaughnessy, C D; Popma, J

2000-11-15

A new martensitic nitinol stent with improved flexibility and radiopacity was tested to evaluate whether these differences improve initial or long-term outcome. Patients who underwent percutaneous revascularization of a discrete native coronary lesion were randomly assigned to the new stent (PARAGON, n = 349) or to the first-generation Palmaz-Schatz (PS) stent (n = 339). The primary end point was target vessel failure at 6 months (a composite of cardiac or noncardiac death, any infarction in the distribution of the treated vessel, or clinically indicated target vessel revascularization). Secondary end points were, among others, device and procedural success and angiographic restenosis. Mean age was 62 years; diabetes was present in 21% of patients, prior bypass surgery in 6%, and recent infarction in 22% (p = NS for comparison between the 2 randomized arms). The PARAGON stent group had smaller reference vessels (2.97 vs 3.05 mm, p = 0.05), more prior restenosis (8.0% vs 4.5%, p = 0.07), and a longer average stent length (21.3 vs 19.4 mm, p < 0.05). Device success was significantly higher in the PARAGON arm (99.1% vs 94.3%, p < 0.05). Death and infarction at 6-month follow-up were infrequent in both groups. There was no significant difference in death (2.0% vs 1.2%, p = 0.546), but a higher rate of infarction for the PARAGON cohort (9.2% vs 4.7%, p = 0.025). Although target vessel failure (20.3% vs 12.4%, p = 0.005) and target lesion revascularization (12.0% vs 5.9%, p = 0.005) were higher in the PARAGON group, there was no significant difference in 6-month follow-up in in-stent minimal lumen diameter or in the rate of binary angiographic restenosis. Both PARAGON and PS stents are safe and associated with infrequent adverse events. The PARAGON stent can be delivered more frequently than the first-generation PS stent. Although there was no significant difference in in-stent minimal lumen diameter or the frequency of angiographic restenosis, clinical restenosis was

Management of JJ stent-related symptoms.

PubMed

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.

[A new generation of urethral stents--Allium in the therapy of symptomatic prostatic enlargement of various etiology].

PubMed

Marković, B B; Marković, Z; Yachia, D; Hadzi, Djokić J

2007-01-01

A number of urethral stents made of different materials, with different time of indwelling and different designs, primarily based on the vascular stent concept, have been applied in the clinical practice so far. According to the published studies, urethral stents have justified their clinical application, however with certain limitations. Within an attempt to overcome the limitations, a covered, temporary urethral stent was initially designed by Daniel Yachie and Ijko Markovi in Allium corporation from Israel. With its triangular shape, the stent is a replica of the obstructive prostatic urethral lumen. In has been applied in a series of 14 patients with lower urinary tract symptoms caused by the obstruction at the level of the prostatic urethra. The subjects were averagely aged 77.4 +/- 5.1 years. Allium prostatic stent remained in place in the patients for 4.93 +/- 3.17 months, at the average.

21 CFR 884.3900 - Vaginal stent.

Code of Federal Regulations, 2010 CFR

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...

Targeted stent use in clinical practice based on evidence from the Basel Stent Cost Effectiveness Trial (BASKET).

PubMed

Brunner-La Rocca, Hans-Peter; Kaiser, Christoph; Pfisterer, Matthias

2007-03-01

It is unknown which patients benefit most from drug-eluting stents (DES) against bare-metal stents (BMS) in a long-term clinical outcome. To address this question, data from 826 consecutive patients with angioplasty, randomized 2:1 to DES vs. BMS, with an 18-month follow-up for cardiac death/myocardial infarction (MI) and non-MI-related target-vessel revascularization (TVR) were analysed for interactions between stent type and patient/vessel characteristics predicting events. Rates of 18-month TVRs were lower with DES vs. BMS use (7.5 vs. 11.6%, P = 0.05), but similar for both stents regarding cardiac death/MI (DES, 8.4%; BMS, 7.5%; P = 0.70). Significant interactions between stent type and two multivariable event predictors were identified: small stents (<3.0 mm) and bypass graft stenting. In these patient groups together (n = 268, 32%), DES reduced non-MI-related TVR (HR = 0.44; P = 0.02) and cardiac death/MI (HR = 0.44; P = 0.04), whereas in the other 558 patients (68%) TVR rate was similar (HR = 0.75; P = 0.38) and cardiac death/MI rate increased after DES (HR = 2.07; P = 0.05). Patients with angioplasty of small vessels or bypass grafts seem to benefit from DES use, in long-term outcome, in contrast to patients with large native vessel stenting where there might even be late harm. Still, this hypothesis needs to be tested prospectively.

Pathological mechanisms of left main stent failure.

PubMed

Mori, Hiroyoshi; Torii, Sho; Harari, Emanuel; Jinnouchi, Hiroyuki; Brauman, Ryan; Smith, Samantha; Kutys, Robert; Fowler, David; Romero, Maria; Virmani, Renu; Finn, Aloke V

2018-07-15

Despite the increasing use of left main (LM) percutaneous coronary intervention (LM-PCI), there have been no pathological studies devoted to understanding the causes of LM stent failure. We aimed to systematically determine the pathological mechanisms of LM stent failure. From the CVPath Stent registry, a total of 46 lesions were identified to have LM-PCI. Pathologic stent failure (PSF) was defined as stent thrombosis, restenosis and in-stent chronic total occlusion (CTO). Failed and patent LM stented lesions were pathologically assessed to determine predictors of PSF. Malapposition and uncovered struts were numerically greater in the LM ostium, body, and bifurcation while neointimal thickness was relatively greater in bifurcation and proximal circumflex. In this study cohort, half of the lesions (n = 23) showed PSF. Stent thrombosis (ST, n = 18) was the major mode of PSF followed by in-stent CTO (n = 4) and restenosis (n = 1). Failed lesions showed significantly greater prevalence of malapposition >20% of struts/section (65% vs. 13%, P < 0.01), stent struts crossing an ostial side branch >30% of the circumference (48% vs. 13%, P < 0.01) and uncovered struts >30% (57% vs. 18%, P = 0.03). In multivariate analysis, the prevalence of malapposition >20% was the strongest risk factor for PSF (Odds ratio 8.0, 95% confidence interval 1.8-45.4, P < 0.01) followed by struts crossing an ostial side branch >30% (Odds ratio 4.2, 95% confidence interval 0.8-24.7, P = 0.09). Our data demonstrate the main pathological predictors for LM stent failure are malapposition and struts crossing an ostial side branch and suggest that imaging-guided PCI may be important. Copyright © 2018 Elsevier B.V. All rights reserved.

Iliocaval Confluence Stenting for Chronic Venous Obstructions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graaf, Rick de, E-mail: r.de.graaf@mumc.nl; Wolf, Mark de, E-mail: markthewolf@gmail.com; Sailer, Anna M., E-mail: anni.sailer@mumc.nl

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) ormore » 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.« less

Patient-Centered Tablet Application for Improving Medication Adherence after a Drug-Eluting Stent.

PubMed

Shah, Vicki; Dileep, Anandu; Dickens, Carolyn; Groo, Vicki; Welland, Betty; Field, Jerry; Baumann, Matthew; Flores, Jose D; Shroff, Adhir; Zhao, Zhongsheng; Yao, Yingwei; Wilkie, Diana J; Boyd, Andrew D

2016-01-01

This study's objective was to evaluate a patient-centered educational electronic tablet application, "My Interventional Drug-Eluting Stent Educational App" (MyIDEA) to see if there was an increase in patient knowledge about dual antiplatelet therapy (DAPT) and medication possession ratio (MPR) compared to treatment as usual. In a pilot project, 24 elderly (≥50 years old) research participants were recruited after a drug-eluting stent. Eleven were randomized to the control arm and 13 to the interventional arm. All the participants completed psychological and knowledge questionnaires. Adherence was assessed through MPR, which was calculated at 3 months for all participants who were scheduled for second and third follow-up visits. Relative to control, the interventional group had a 10% average increase in MPR. As compared to the interventional group, more patients in the control group had poor adherence (<80% MPR). The psychological data revealed a single imbalance in anxiety between the control and interventional groups. On average, interventional participants spent 21 min using MyIDEA. Consumer health informatics has enabled us to engage patients with their health data using novel methods. Consumer health technology needs to focus more on patient knowledge and engagement to improve long-term health. MyIDEA takes a unique approach in targeting DAPT from the onset. MyIDEA leverages patient-centered information with clinical care and the electronic health record highlighting the patients' role as a team member in their own health care. The patients think critically about adverse events and how to solve issues before leaving the hospital.

Plastic biliary stents for benign biliary diseases.

PubMed

Perri, Vincenzo; Familiari, Pietro; Tringali, Andrea; Boskoski, Ivo; Costamagna, Guido

2011-07-01

Biliary plastic stenting plays a key role in the endoscopic management of benign biliary diseases. Complications following surgery of the biliary tract and liver transplantation are amenable to endoscopic treatment by plastic stenting. Insertion of an increasing number of plastic stents is currently the method of choice to treat postoperative biliary strictures. Benign biliary strictures secondary to chronic pancreatitis or primary sclerosing cholangitis may benefit from plastic stenting in select cases. There is a role for plastic stent placement in nonoperative candidates with acute cholecystitis and in patients with irretrievable bile duct stones. Copyright © 2011 Elsevier Inc. All rights reserved.

Clinical Results and Mechanical Properties of the Carotid CGUARD Double-Layered Embolic Prevention Stent.

PubMed

Wissgott, Christian; Schmidt, Wolfram; Brandt-Wunderlich, Christoph; Behrens, Peter; Andresen, Reimer

2017-02-01

To report early clinical outcomes with a novel double-layer stent for the internal carotid artery (ICA) and the in vitro investigation of the stent's mechanical properties. A prospective single-center study enrolled 30 consecutive patients (mean age 73.1±6.3 years; 21 men) with symptomatic (n=25) or high-grade (n=5) ICA stenosis treated with the new double-layer carotid CGUARD Embolic Prevention System (EPS) stent, which has an inner open-cell nitinol design with an outer closed-cell polyethylene terephthalate layer. The average stenosis of the treated arteries was 84.1%±7.9% with a mean lesion length of 16.6±2.1 mm. In the laboratory, 8×40-mm stents where tested in vitro with respect to their radial force during expansion, the bending stiffness of the stent system and the expanded stent, as well as the collapse pressure in a thin and flexible sheath. The wall adaptation was assessed using fluoroscopy after stent release in step and curved vessel models. The stent was successfully implanted in all patients. No peri- or postprocedural complications occurred; no minor or major stroke was observed in the 6-month follow-up. The bending stiffness of the expanded stent was 63.1 N·mm 2 and (not unexpectedly) was clearly lower than that of the stent system (601.5 N·mm 2 ). The normalized radial force during expansion of the stent to 7.0 mm, consistent with in vivo sizing, was relatively high (0.056 N/mm), which correlates well with the collapse pressure of 0.17 bars. Vessel wall adaptation was harmonic and caused no straightening of the vessel after clinical application. Because of its structure, the novel CGUARD EPS stent is characterized by a high flexibility combined with a high radial force and very good plaque coverage. These first clinical results demonstrate a very safe implantation behavior without any stroke up to 6 months after the procedure.

Structural analysis of two different stent configurations.

PubMed

Simão, M; Ferreira, J M; Mora-Rodriguez, J; Ramos, H M

2017-06-01

Two different stent configurations (i.e. the well known Palmaz-Schatz (PS) and a new stent configuration) are mechanically investigated. A finite element model was used to study the two geometries under combining loads and a computational fluid dynamic model based on fluid structure interaction was developed investigating the plaque and the artery wall reactions in a stented arterial segment. These models determine the stress and displacement fields of the two stents under internal pressure conditions. Results suggested that stent designs cause alterations in vascular anatomy that adversely affect arterial stress distributions within the wall, which have impact in the vessel responses such as the restenosis. The hemodynamic analysis shows the use of new stent geometry suggests better biofluid mechanical response such as the deformation and the progressive amount of plaque growth.

Drug-eluting versus bare-metal coronary stents: where are we now?

PubMed

Amoroso, Nicholas S; Bangalore, Sripal

2012-11-01

Drug-eluting stents have dramatically reduced the risk of restenosis, but concerns of an increased risk of stent thrombosis have provided uncertainty about their use. Recent studies have continued to show improved procedural and clinical outcomes with drug-eluting stents both in the setting of acute coronary syndromes and stable coronary artery disease. Newer generation drug-eluting stents (especially everolimus-eluting stents) have been shown to be not only efficacious but also safe with reduced risk of stent thrombosis when compared with bare-metal stents, potentially changing the benchmark for stent safety from bare-metal stents to everolimus-eluting stents. While much progress is being made in the development of bioabsorbable polymer stents, nonpolymer stents and bioabsorbable stent technology, it remains to be seen whether these stents will have superior safety and efficacy outcomes compared with the already much improved rates of revascularization and stent thrombosis seen with newer generation stents (everolimus-eluting stents and resolute zotarolimus-eluting stents).

Auxetic coronary stent endoprosthesis: fabrication and structural analysis.

PubMed

Amin, Faisal; Ali, Murtaza Najabat; Ansari, Umar; Mir, Mariam; Minhas, Muhammad Asim; Shahid, Wakeel

2015-07-04

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. The auxetic design was obtained via laser cutting, and surface treatment was performed with acid pickling and electropolishing, followed by an annealing process. In vitro mechanical analysis was performed to analyze the mechanical performance of the auxetic coronary stent. Scanning electronic microscopy (SEM) was used to determine the effects of fabrication processes on the topography of the auxetic stent. The elastic recoil (3.3%) of the in vitro mechanical analysis showed that the auxetic stent design effectively maintained the luminal patency of the coronary artery. Also, the auxetic coronary stent showed no foreshortening, therefore it avoids the problem of stent migration, by expanding in both the radial and longitudinal directions. By virtue of its synclastic behavior, the auxetic stent bulges outward when it is radially expanded through an inflated balloon.

Recent Advances in Drug Eluting Stents

PubMed Central

Puranik, Amey S.; Dawson, Eileen R.; Peppas, Nicholas A.

2013-01-01

One of the most common medical interventions to reopen an occluded vessel is the implantation of a coronary stent. While this method of treatment is effective initially, restenosis, or the re-narrowing of the artery frequently occurs largely due to neointimal hyperplasia of smooth muscle cells. Drug eluting stents were developed in order to provide local, site-specific, controlled release of drugs that can inhibit neointima formation. By implementing a controlled release delivery system it may be possible to control the time release of the pharmacological factors and thus be able to bypass some of the critical events associated with stent hyperplasia and prevent the need for subsequent intervention. However, since the advent of first-generation drug eluting stents, long-term adverse effects have raised concerns regarding their safety. These limitations in safety and efficacy have triggered considerable research in developing biodegradable stents and more potent drug delivery systems. In this review, we shed light on the current state-of-the-art in drug eluting stents, problems related to them and highlight some of the ongoing research in this area. PMID:23117022

Metallic ureteral stents in malignant ureteral obstruction: short-term results and radiological features predicting stent failure in patients with non-urological malignancies.

PubMed

Chow, Po-Ming; Hsu, Jui-Shan; Wang, Shuo-Meng; Yu, Hong-Jheng; Pu, Yeong-Shiau; Liu, Kao-Lang

2014-06-01

To provide short-term result of the metallic ureteral stent in patients with malignant ureteral obstruction and identify radiological findings predicting stent failure. The records of all patients with non-urological malignant diseases who have received metallic ureteral stents from July 2009 to March 2012 for ureteral obstruction were reviewed. Stent failure was detected by clinical symptoms and imaging studies. Survival analysis was used to estimate patency rates and factors predicting stent failure. A total of 74 patients with 130 attempts of stent insertion were included. A total of 113 (86.9 %) stents were inserted successfully and 103 (91.2 %) achieved primary patency. After excluding cases without sufficient imaging data, 94 stents were included in the survival analysis. The median functional duration of the 94 stents was 6.2 months (range 3-476 days). Obstruction in abdominal ureter (p = 0.0279) and lymphatic metastasis around ureter (p = 0.0398) were risk factors for stent failure. The median functional durations of the stents for abdominal and pelvic obstructions were 4.5 months (range 3-263 days) and 6.5 months (range 4-476 days), respectively. The median durations of the stents with and without lymphatic metastasis were 5.3 months (range 4-398 days) and 7.8 months (range 31-476 days), respectively. Metallic ureteral stents are effective and safe in relieving ureteral obstructions resulting from non-urological malignancies, and abdominal ureteral obstruction and lymphatic metastasis around ureter were associated with shorter functional duration.

Endoscopic stenting for benign upper gastrointestinal strictures and leaks.

PubMed

Sharaiha, Reem Z; Kim, Katherine J; Singh, Vikesh K; Lennon, Anne Marie; Amateau, Stuart K; Shin, Eun Ji; Canto, Marcia Irene; Kalloo, Anthony N; Khashab, Mouen A

2014-01-01

Self-expandable metal stents (SEMS) and self-expandable plastic stents (SEPS) maybe used for the treatment of benign upper gastrointestinal (GI) leaks and strictures. This study reviewed our experience with stent insertions in patients with benign upper GI conditions. Patients who underwent stent placement for benign upper GI strictures and leaks between March 2007 and April 2011 at a tertiary referral academic center were studied using an endoscopic database and electronic patient records. The technical success, complications, and clinical improvement after stent removal were compared according to type of stent. The outcomes measured were clinical response, adverse events, and predictors of stent migration. Thirty-eight patients (50 % male, mean age = 54 years, range = 12-82) underwent 121 endoscopic procedures. Twenty patients had stents placed for strictures, and 18 had stents placed for leaks. Stent placement was technically successful in all patients. The average duration of stent placement was 54 days (range = 18-118). Clinical improvement immediately after stent placement was seen in 29 of the 38 patients (76.3 %). Immediate post-procedure adverse events occurred in 8 patients. Late adverse events were seen in 18 patients. Evidence of stent migration occurred in 16 patients and was seen in 42 of the 118 successfully placed stents (35.5 %). Migration was more frequent with fully covered SEMS (p = 0.002). After stent removal, 27 patients were evaluable for long-term success (median follow-up time of 283 days, IQR 38-762). Resolution of strictures or leaks was seen in 11 patients (40.7 %). Predictors for long-term success included increasing age and if the stent did not cross the GE junction. Placement of SEPS and SEMS for benign refractory strictures and fistulas has modest long-term clinical efficacy and is limited by a significant migration rate. Stent migration is common and frequent with fully covered SEMS compared to other types of stents, regardless of

Risk factors for proximal migration of biliary tube stents

PubMed Central

Kawaguchi, Yoshiaki; Ogawa, Masami; Kawashima, Yohei; Mizukami, Hajime; Maruno, Atsuko; Ito, Hiroyuki; Mine, Tetsuya

2014-01-01

AIM: To analyze the risk factors for biliary stent migration in patients with benign and malignant strictures. METHODS: 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. RESULTS: 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 < 0.001); and 10-Fr sized stents (P < 0.001). Retrieval of the migrated 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. CONCLUSION: Migration of tube stents

Risk factors for proximal migration of biliary tube stents.

PubMed

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 < 0.001); and 10-Fr sized stents (P < 0.001). Retrieval of the migrated 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

Modifying effect of dual antiplatelet therapy on incidence of stent thrombosis according to implanted drug-eluting stent type.

PubMed

Camenzind, Edoardo; Boersma, Eric; Wijns, William; Mauri, Laura; Rademaker-Havinga, Tessa; Ordoubadi, Farzin Fath; Suttorp, Maarten J; Al Kurdi, Mohammad; Steg, Ph Gabriel

2014-08-01

To investigate the putative modifying effect of dual antiplatelet therapy (DAPT) use on the incidence of stent thrombosis at 3 years in patients randomized to Endeavor zotarolimus-eluting stent (E-ZES) or Cypher sirolimus-eluting stent (C-SES). Of 8709 patients in PROTECT, 4357 were randomized to E-ZES and 4352 to C-SES. Aspirin was to be given indefinitely, and clopidogrel/ticlopidine for ≥ 3 months or up to 12 months after implantation. Main outcome measures were definite or probable stent thrombosis at 3 years. Multivariable Cox regression analysis was applied, with stent type, DAPT, and their interaction as the main outcome determinants. Dual antiplatelet therapy adherence remained the same in the E-ZES and C-SES groups (79.6% at 1 year, 32.8% at 2 years, and 21.6% at 3 years). We observed a statistically significant (P = 0.0052) heterogeneity in treatment effect of stent type in relation to DAPT. In the absence of DAPT, stent thrombosis was lower with E-ZES vs. C-SES (adjusted hazard ratio 0.38, 95% confidence interval 0.19, 0.75; P = 0.0056). In the presence of DAPT, no difference was found (1.18; 0.79, 1.77; P = 0.43). A strong interaction was observed between drug-eluting stent type and DAPT use, most likely prompted by the vascular healing response induced by the implanted DES system. These results suggest that the incidence of stent thrombosis in DES trials should not be evaluated independently of DAPT use, and the optimal duration of DAPT will likely depend upon stent type (Clinicaltrials.gov number NCT00476957). Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

TACE Combined with Implantation of Irradiation Stent Versus TACE Combine with Bare Stent for HCC Complicated by IVCTT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Qing-hui; Zhang, Wen; Liu, Qing-xin

PurposeThis study was designed to evaluate the safety and efficacy of transarterial chemoembolization (TACE) combined with intra-IVC implantation of an irradiation stent for the treatment of hepatocellular carcinoma (HCC) complicated by inferior vena cava tumor thrombosis (IVCTT).MethodsSixty-one consecutive patients with HCC complicated by IVCTT treated by TACE combined with IVC stenting were retrospectively analysed. IVC stenting was performed using a stent loaded with {sup 125}I seeds strands (the irradiation stent) in 33 patients (Group A) and 28 patients with a bare stent (Group B). Propensity score matching eliminated the baseline differences. Overall survival, oedema related to IVC obstruction remission ratemore » and procedure-related adverse events were compared between the two groups.ResultsThe adverse effect rate was similar for both Group A and Group B patients, and complications were adequately handled by medical treatment. TACE combined with implantation of an irradiation stent showed a significant median survival benefit over TACE combined with a bare stent, with a median survival time of 203.0 ± 28.135 days versus 93.0 ± 24.341 days (p = 0.006). The propensity score-matched (24 pairs) cohort analyses (200 ± 31.231 days vs. 66 ± 23.270 days, p = 0.019). The oedema remission rate was 97.0 % in group A patients and 96.4 % in group B, respectively. TACE-irradiation stent and object tumor response were the independent prognostic factors of favorable survival.ConclusionsTACE combined with irradiation stent implantation is a safe and effective treatment modality for patients with HCC complicated by IVCTT and may extend their survival time.« less

Randomized multicenter study of multiple plastic stents vs. covered self-expandable metallic stent in the treatment of biliary stricture in chronic pancreatitis.

PubMed

Haapamäki, Carola; Kylänpää, Leena; Udd, Marianne; Lindström, Outi; Grönroos, Juha; Saarela, Arto; Mustonen, Harri; Halttunen, Jorma

2015-07-01

The use of covered self-expandable metallic stents (cSEMS) in benign biliary indications is evolving. The aim of the study was to assess the safety and feasibility of cSEMS compared with multiple plastic stents in the treatment of benign biliary stricture (BBS) caused by chronic pancreatitis. This was a prospective, multicenter, randomized study of 60 patients with BBS caused by chronic pancreatitis. All patients received an initial plastic stent before randomization. At randomization, the stent was replaced either with a single cSEMS or three plastic stents. After 3 months, the position of the cSEMS was checked or another three plastic stents were added. At 6 months after randomization, all stents were removed. Clinical follow-up including abdominal ultrasound and laboratory tests were performed at 6 months and 2 years after stent removal. Two patients dropped out of the cSEMS group before stent removal. In April 2014, the median follow-up was 40 months (range 1 - 66 months). The 2-year, stricture-free success rate was 90 % (95 % confidence interval [CI] 72 % - 97 %) in the plastic stent group and 92 % (95 %CI 70 % - 98 %) in the cSEMS group (P = 0.405). There was one late recurrence in the plastic stent group 50 months after stent removal. Stent migration occurred three times (10 %) in the plastic stent group and twice in the cSEMS group (7 %; P = 1.000). A 6-month treatment with either six 10-Fr plastic stents or with one 10-mm cSEMS produced good long-term relief of biliary stricture caused by chronic pancreatitis.Study registered at ClinicalTrials.gov (NCT01085747). © Georg Thieme Verlag KG Stuttgart · New York.

Wall shear stress distributions on stented patent ductus arteriosus

NASA Astrophysics Data System (ADS)

Kori, Mohamad Ikhwan; Jamalruhanordin, Fara Lyana; Taib, Ishkrizat; Mohammed, Akmal Nizam; Abdullah, Mohammad Kamil; Ariffin, Ahmad Mubarak Tajul; Osman, Kahar

2017-04-01

A formation of thrombosis due to hemodynamic conditions after the implantation of stent in patent ductus arteriosus (PDA) will derived the development of re-stenosis. The phenomenon of thrombosis formation is significantly related to the distribution of wall shear stress (WSS) on the arterial wall. Thus, the aims of this study is to investigate the distribution of WSS on the arterial wall after the insertion of stent. Three dimensional model of patent ductus arteriosus inserted with different types of commercial stent are modelled. Computational modelling is used to calculate the distributions of WSS on the arterial stented PDA. The hemodynamic parameters such as high WSS and WSSlow are considered in this study. The result shows that the stented PDA with Type III stent has better hemodynamic performance as compared to others stent. This model has the lowest distributions of WSSlow and also the WSS value more than 20 dyne/cm2. From the observed, the stented PDA with stent Type II showed the highest distributions area of WSS more than 20 dyne/cm2. This situation revealed that the high possibility of atherosclerosis to be developed. However, the highest distribution of WSSlow for stented PDA with stent Type II indicated that high possibility of thrombosis to be formed. In conclusion, the stented PDA model calculated with the lowest distributions of WSSlow and WSS value more than 20dyne/cm2 are considered to be performed well in stent hemodynamic performance as compared to other stents.

Use of double pigtail stent in hypospadias surgery.

PubMed

Chang, Paul C Y; Yeh, Ming-Lun; Chao, Chun-Chih; Chang, Chi-Jen

2011-01-01

Various types and materials of stents have been used for urinary diversion in hypospadias surgery. We evaluated whether double pigtail stents are superior to straight silicone stents. We conducted a retrospective chart review of all patients who underwent hypospadias surgery with straight silicone or double pigtail stents between November 1997 and October 2005. Comparisons were made between the two groups specifically with regard to the complication rates. A total of 86 patients were included. The complication rates in patients who received double pigtail stents were significantly reduced as compared with those who received straight silicon stents. There was less wound disruption associated with early stent dislodgement in the double pigtail group compared with the straight silicone group (3.2%vs. 17.4%, p< 0.05). The rate of urethrocutaneous fistula was also lower in the double pigtail stent group (12.7%vs. 30.4%). Subjectively, there was also improved patient comfort and parent anxiety in the double pigtail stent group. Double pigtail stent is a suitable material for urinary diversion in hypospadias surgery. It not only reduces patient discomfort, but also decreases complication rates in hypospadias surgery. Copyright © 2011 Asian Surgical Association. Published by Elsevier B.V. All rights reserved.

Reduction of Late In-Stent Stenosis in a Porcine Coronary Artery Model by Cobalt Chromium Stents with a Nanocoat of Polyphosphazene (Polyzene-F)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stampfl, Ulrike; Sommer, Christof-Matthias; Thierjung, Heidi

2008-11-15

The purpose of this study was to investigate the potential of nanoscale coating with the highly biocompatible polymer Polyzene-F (PZF), in combination with cobalt chromium and stainless steel stents, to reduce in-stent stenosis, thrombogenicity, and vessel wall injury and inflammation. One bare cobalt chromium, PZF-nanocoated stainless steel or PZF-nanocoated cobalt chromium stent was implanted in right coronary artery of 30 mini-pigs (4- or 12-week follow-up). Primary study end points were in-stent stenosis and thrombogenicity. Secondary study end points were vessel wall injury and inflammation as evaluated by microscopy and a new immunoreactivity score applying C-reactive protein (CRP), tumor-necrosis factor alphamore » (TNF{alpha}), and TGF{beta}. At 12 weeks, angiography showed a significantly lower average loss in lumen diameter (2.1% {+-} 3.05%) in PZF-nanocoated cobalt chromium stents compared with stents in the other groups (9.73% {+-} 4.93% for bare cobalt chromium stents and 9.71% {+-} 7% for PZF-nanocoated stainless steel stents; p = 0.04), which was confirmed at microscopy (neointima 40.7 {+-} 16 {mu}m in PZF-nanocoated cobalt chromium stents, 74.7 {+-} 57.6 {mu}m in bare cobalt chromium stents, and 141.5 {+-} 109 {mu}m in PZF-nanocoated stainless steel stents; p = 0.04). Injury and inflammation scores were low in all stents and were without significant differences. PZF-nanocoated cobalt chromium stents provided the highest efficacy in reducing in-stent stenosis at long-term follow-up. The PZF nanocoat proved to be biocompatible with respect to thromboresistance and inflammation. Our data suggest that its combination with cobalt chromium stents might provide an interesting passive stent platform.« less

Fiber laser micromachining of magnesium alloy tubes for biocompatible and biodegradable cardiovascular stents

NASA Astrophysics Data System (ADS)

Demir, Ali Gökhan; Previtali, Barbara; Colombo, Daniele; Ge, Qiang; Vedani, Maurizio; Petrini, Lorenza; Wu, Wei; Biffi, Carlo Alberto

2012-02-01

Magnesium alloys constitute an attractive solution for cardiovascular stent applications due to their intrinsic properties of biocompatibility and relatively low corrosion resistance in human-body fluids, which results in as a less intrusive treatment. Laser micromachining is the conventional process used to cut the stent mesh, which plays the key role for the accurate reproduction of the mesh design and the surface quality of the produced stent that are important factors in ensuring the mechanical and corrosion resistance properties of such a kind of devices. Traditionally continuous or pulsed laser systems working in microsecond pulse regime are employed for stent manufacturing. Pulsed fiber lasers on the other hand, are a relatively new solution which could balance productivity and quality aspects with shorter ns pulse durations and pulse energies in the order of mJ. This work reports the study of laser micromachining and of AZ31 magnesium alloy for the manufacturing of cardiovascular stents with a novel mesh design. A pulsed active fiber laser system operating in nanosecond pulse regime was employed for the micromachining. Laser parameters were studied for tubular cutting on a common stent material, AISI 316L tubes with 2 mm in diameter and 0.2 mm in thickness and on AZ31 tubes with 2.5 mm in diameter and 0.2 in thickness. In both cases process parameters conditions were examined for reactive and inert gas cutting solutions and the final stent quality is compared.

Mechanisms of Biliary Plastic Stent Occlusion and Efforts at Prevention

PubMed Central

Kwon, Chang-Il; Lehman, Glen A.

2016-01-01

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

Urinary tract infections associated with ureteral stents: A Review.

PubMed

Liaw, A; Knudsen, B

2016-10-01

We review the literature on infections associated with ureteral stents and new technologies aimed at preventing them. Ureteral stent placement is one of the most common urologic procedures, but carries a comparatively high morbidity. Infection is one of the most common stent-associated morbidities. Several new stent materials and coatings have been proposed and tested to reduce stent-associated infections. We review the current methods of preventing bacterial infection, including antibiotic prophylaxis and minimising dwell time. We look at the science underlying infection and biofilm formation on stents. Several new stent materials and coatings are described, as well as the studies underlying their mechanism of action. While many promising ideas for new stent coatings and materials have been tested, no significant improvement to current polyurethane stent technology is commonly available or used. The basic principles of antibiotic prophylaxis at time of insertion, avoiding contamination, and minimising dwell times remain the best methods to prevent stent-associated infections.

An ovine in vivo framework for tracheobronchial stent analysis.

PubMed

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.

Efficacy and safety of biodegradable stents for refractory benign esophageal strictures: the BEST (Biodegradable Esophageal Stent) study.

PubMed

Repici, Alessandro; Vleggaar, Frank P; Hassan, Cesare; van Boeckel, Petra G; Romeo, Fabio; Pagano, Nicola; Malesci, Alberto; Siersema, Peter D

2010-11-01

Benign esophageal strictures refractory to standard dilation therapy present a challenging problem. Temporary plastic and metal stents have been proposed with inconclusive results. To evaluate the efficacy and safety of a new biodegradable stent for the treatment of refractory benign esophageal strictures (RBESs). Prospective study from 2 European endoscopy centers. Twenty-one patients (11 men/10 women, mean age 60.2 ± 17.6 years) with RBESs defined according to the Kochman criteria treated by placement of a biodegradable stent (Ella stent). Clinical and endoscopic follow-up was scheduled at 1, 2, 3, and 6 months and later only in case of dysphagia recurrence. Pre- and poststenting dysphagia status was graded according to a 5-point scale. Minor and major complication rates were prospectively assessed. Stent insertion was technically successful in all of the patients. At 4 and 7 weeks, stent migration occurred in 2 patients (9.5%). At 3-month endoscopy, the stent appeared to be almost completely fragmented in all remaining patients. The median pre- and poststenting dysphagia scores were 3 (range 3-4) and 1 (range 0-2), respectively (P < .01), with a median follow-up of 53 weeks (range 25-88 weeks). In detail, 9 of 20 patients (45%) were dysphagia free at the end of the follow-up. No major complications occurred. Severe poststenting pain requiring analgesics developed in 3 patients, and minor bleeding was observed in 1 patient. Limited follow-up; nonrandomized study. In this preliminary study, the biodegradable stent showed a favorable risk/benefit ratio, achieving complete relief of dysphagia in nearly 50% of RBES patients without the occurrence of major complications. The use of this stent may be a valuable alternative to repeat endoscopic dilation. Larger studies with longer follow-up are needed. Copyright © 2010 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

Computational Study of Axial Fatigue for Peripheral Nitinol Stents

NASA Astrophysics Data System (ADS)

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

2014-07-01

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

Comparison of outcomes among secondary covered metallic, uncovered metallic, and plastic biliary stents in treating occluded primary metallic stents in malignant distal biliary obstruction.

PubMed

Cho, Jae Hee; Jeon, Tae Joo; Park, Jeong Youp; Kim, Hee Man; Kim, Yoon Jae; Park, Seung Woo; Chung, Jae Bock; Song, Si Young; Bang, Seungmin

2011-02-01

The self-expandable metallic stent (SEMS) has been widely used for unresectable malignant biliary obstruction but eventually becomes occluded by tumor ingrowth/overgrowth and sludge. Therefore, we aimed to determine the therapeutic effectiveness of secondary stents and to find differences according to various combinations of the first and second stents for the management of occluded SEMSs in patients with malignant distal biliary obstruction. Between 1999 and November 2008, 77 patients with malignant biliary obstruction underwent secondary biliary stent placement as "stent-in-stent" at three university hospitals in Korea (40 covered, 26 uncovered, and 11 plastic stents). The membrane of the covered SEMS was regarded as the barrier against tumor ingrowth. We categorized the patients into three groups based on whether the covered SEMS was either the first or the second stent: membrane-SEMS (18 covered-covered; 9 covered-uncovered; 22 uncovered-covered SEMS), bare-SEMS (17 uncovered-uncovered SEMS), and plastic stent (3 covered-plastic; 8 uncovered-plastic). The median patency of second stents was 138, 109, and 88 days (covered, uncovered, and plastic stents). The second covered SEMSs had a significantly longer patency than plastic stents (p=0.047). In a multivariate analysis including membrane-SEMS, bare-SEMS, and plastic stent groups, the bare-SEMS had a worse cumulative stent patency (HR=2.04, CI=1.08-3.86) and survival time (HR=2.37, CI=1.25-4.49) than the membrane-SEMS. Patients with ampulla of Vater cancer had better stent patency (HR=0.27, CI=0.08-0.98) and survival (HR=0.17, CI=0.04-0.77) than those with other pancreatobiliary malignancies. In addition, antitumor treatment prolonged survival time (HR=0.50, CI=0.26-0.99). The placement of additional biliary stents using the "stent-in-stent" method is an effective treatment for an occluded metallic primary stent. In addition, double biliary SEMS placement using at least one covered SEMS (in the primary and

Perioperative antiplatelet management in patients with coronary artery stenting.

PubMed

Tandar, Anwar; Velagapudi, Krishna N; Wilson, Brent D; Boden, William E

2012-04-01

Coronary artery disease is the primary cause of mortality in men and women in the United States. Transcatheter coronary intervention is the mainstay of treatment for patients with acute coronary artery disease presentations and patients with stable disease. Although percutaneous intervention initially only included balloon angioplasty, it now typically involves the placement of intracoronary stents. To overcome the limitations of bare-metal stents, namely in-stent restenosis, stents have been developed that remove pharmaceuticals that reduce neointimal hyperplasia and in-stent restenosis. However, these pharmaceutical agents also delay stent endothelialization, posing a prolonged risk of in situ thrombosis. Placement of an intracoronary stent (eg, bare-metal or drug-eluting stent) requires dual antiplatelet therapy to prevent the potentially life-threatening complication of stent thrombosis. The optimal duration of dual antiplatelet therapy following stent placement is unknown. This article discusses the factors to be considered when deciding when dual antiplatelet therapy can be safely discontinued. Unfortunately, in the hospital setting, this decision to interrupt dual antiplatelet therapy frequently must be made shortly after stent placement because of unanticipated surgical procedures or other unforeseen complications. The decision of when dual antiplatelet therapy can be safely interrupted needs to be individualized for each patient and involves factoring in the type of stent; the location and complexity of the lesion stented; post-stent lesion characteristics; the amount of time since stent placement; and the antiplatelet regimen currently in use, along with its implication for bleeding during the proposed procedure. Having a protocol in place, such as the protocol described in this article, can help guide this decision-making process and avoid confusion and potential error.

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

PubMed

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.

Advances in Ureteral Stent Design

NASA Astrophysics Data System (ADS)

Denstedt, John D.

2007-04-01

Ureteral stents are commonly used in urolithiasis patients for relief of obstruction or in association with stone treatments such as ureteroscopy and extracorporeal shock wave lithotripsy. There are currently many different bulk materials and coatings available for the manufacture of ureteral stents, however the ideal material has yet to be discovered. All potential biomaterials must undergo rigorous physical and biocompatibility testing before commercialization and use in humans. Despite significant advances in basic science research involving biocompatibility issues and biofilm formation, infection and encrustation remain associated with the use of biomaterials in the urinary tract. There have been many significant advances in the design of ureteral stents in recent years and these will be highlighted along with a discussion of future aspects of biomaterials and use of stents in association with urolithiasis.

Complications and management of forgotten long-term biliary stents.

PubMed

Sohn, Se Hoon; Park, Jae Hyun; Kim, Kook Hyun; Kim, Tae Nyeun

2017-01-28

To evaluate complications and management outcomes of retained long-term plastic biliary stents. Endoscopic plastic biliary stent placement was performed in 802 patients at Yeungnam University Hospital between January 2000 and December 2014. Follow-up loss with a subsequently forgotten stent for more than 12 mo occurred in 38 patients. We retrospectively examined the cause of biliary stent insertion, status of stents, complications associated with biliary stents and management outcomes of long-term plastic biliary stents. Continuous variables were analyzed using the t test. Observed frequencies in subsets of the study population were compared using Fisher's exact test and χ 2 tests. Statistical significance was defined as P < 0.05 (two-tailed). Mean age of patients was 73.7 ± 12 years and male-to-female ratio was 2.2:1. Indications of plastic biliary stent insertion were bile duct stones (63.2%, 24/38) and benign bile duct stricture (52.6%, 20/38). Mean duration of retained plastic stent was 22.6 ± 12.2 mo, and in 10 cases (26.3%), stents were retained for more than 24 mo. Common bile duct (CBD) stones or sludge were found in most cases (92.1%, 35/38). The most common complication was acute cholangitis (94.7%, 36/38). Stent removal by endoscopic approach was successfully performed in 92.1% (35/38) of the cases. In 3 cases, an additional plastic stent was inserted alongside the previous stent due to failure of the stent removal. Endoscopic removal of bile duct stones was successful in 73.7% (28/38) of the cases. When patients were divided into two groups by duration of stent placement (12 to 24 mo vs over 24 mo), there were no differences in the development of cholangitis, presence of biliary stones, and success rate of endoscopic removal of stones and biliary stents. The most common complication of retained long-term plastic biliary stents was acute cholangitis associated with CBD stones. Endoscopic management was successfully performed in most cases.

Complications and management of forgotten long-term biliary stents

PubMed Central

Sohn, Se Hoon; Park, Jae Hyun; Kim, Kook Hyun; Kim, Tae Nyeun

2017-01-01

AIM To evaluate complications and management outcomes of retained long-term plastic biliary stents. METHODS Endoscopic plastic biliary stent placement was performed in 802 patients at Yeungnam University Hospital between January 2000 and December 2014. Follow-up loss with a subsequently forgotten stent for more than 12 mo occurred in 38 patients. We retrospectively examined the cause of biliary stent insertion, status of stents, complications associated with biliary stents and management outcomes of long-term plastic biliary stents. Continuous variables were analyzed using the t test. Observed frequencies in subsets of the study population were compared using Fisher’s exact test and χ2 tests. Statistical significance was defined as P < 0.05 (two-tailed). RESULTS Mean age of patients was 73.7 ± 12 years and male-to-female ratio was 2.2:1. Indications of plastic biliary stent insertion were bile duct stones (63.2%, 24/38) and benign bile duct stricture (52.6%, 20/38). Mean duration of retained plastic stent was 22.6 ± 12.2 mo, and in 10 cases (26.3%), stents were retained for more than 24 mo. Common bile duct (CBD) stones or sludge were found in most cases (92.1%, 35/38). The most common complication was acute cholangitis (94.7%, 36/38). Stent removal by endoscopic approach was successfully performed in 92.1% (35/38) of the cases. In 3 cases, an additional plastic stent was inserted alongside the previous stent due to failure of the stent removal. Endoscopic removal of bile duct stones was successful in 73.7% (28/38) of the cases. When patients were divided into two groups by duration of stent placement (12 to 24 mo vs over 24 mo), there were no differences in the development of cholangitis, presence of biliary stones, and success rate of endoscopic removal of stones and biliary stents. CONCLUSION The most common complication of retained long-term plastic biliary stents was acute cholangitis associated with CBD stones. Endoscopic management was successfully

Outcomes of secondary self-expandable metal stents versus surgery after delayed initial palliative stent failure in malignant colorectal obstruction.

PubMed

Yoon, Jin Young; Park, Soo Jung; Hong, Sung Pil; Kim, Tae Il; Kim, Won Ho; Cheon, Jae Hee

2013-01-01

When re-intervention is required due to an occluded first colorectal self-expanding metal stent for malignant colorectal obstruction, serious controversies exist regarding whether to use endoscopic re-stenting or surgery. To compare the clinical outcomes in patients who underwent stent re-insertion versus palliative surgery as a second intervention. A total of 115 patients who received either self-expandable metal stent (SEMS) insertion or palliative surgery for treatment of a second occurrence of malignant colorectal obstruction after the first SEMS placement were retrospectively studied between July 2005 and December 2009. The median overall survival (8.2 vs. 15.5 months) and progression-free survival (4.0 vs. 2.7 months) were not significantly different between the stent and surgery groups (p = 0.895 and 0.650, respectively). The median lumen patency in the stent group was 3.4 months and that in the surgery group was 7.9 months (p = 0.003). The immediate complication rate after second stent insertion was 13.9% and late complication rate was observed in 12 of 79 (15.2%) patients. There was no mortality related to the SEMS procedure. The complication and mortality rates associated with palliative surgery were 3.5% (2/57) and 12.3% (7/57), respectively. Although there is no significant difference in the overall survival between stenting and surgery, a secondary stent insertion had a lower mortality rate despite a shorter duration of temporary colorectal decompression compared to that of palliative surgery.

Duplex criteria for determination of in-stent stenosis after angioplasty and stenting of the superficial femoral artery.

PubMed

Baril, Donald T; Rhee, Robert Y; Kim, Justine; Makaroun, Michel S; Chaer, Rabih A; Marone, Luke K

2009-01-01

Endovascular intervention is considered first-line therapy for most superficial femoral artery (SFA) occlusive disease. Duplex ultrasound (DU) criteria for SFA in-stent stenosis and correlation with angiographic data remain poorly defined. This study evaluated SFA-specific DU criteria for the assessment of SFA in-stent stenosis. From May 2003 to May 2008, 330 limbs underwent SFA angioplasty and stenting and were monitored by serial DU imaging. Suspected stenotic lesions underwent angiography and intervention when appropriate. Data pairs of DU and angiographically estimated stenosis stent peak systolic velocity (PSV), the ratio of the stented SFA velocity/proximal SFA velocity, changes in ankle-brachial indices (ABIs), and the percentage of angiographic stenosis were examined. Linear regression and receiver operator characteristic (ROC) curve analyses were used to compare angiographic stenosis with PSV and velocity ratios (Vrs) to establish optimal criteria for determining significant in-stent stenosis. Mean follow-up was 16.9 +/- 8.3 months. Of the 59 limbs that underwent reintervention, 37 (63%) were symptomatic, and 22 (37%) underwent reintervention based on DU findings alone. Linear regression models of PSV and Vr vs degree of angiographic stenosis showed strong adjusted correlation coefficients (R(2) = 0.60, P < .001 and R(2) = 0.55, P < 0.001, respectively). ROC curve analysis showed that to detect a >or=50% in-stent stenosis, a PSV >or=190 had 88% sensitivity, 95% specificity, a 98% positive predictive value (PPV), and a 72% negative predictive value (NPV); for Vr, a ratio of >1.50 had 93% sensitivity, 89% specificity, a 96% PPV, and a 81% NPV. To detect >or=80% in-stent stenosis, a PSV >or=275 had 97% sensitivity, 68% specificity, a 67% PPV, and a 97% NPV; a Vr ratio >or=3.50 had 74% sensitivity, 94% specificity, a 77% PPV, and a 88% NPV

Computational design analysis for deployment of cardiovascular stents

NASA Astrophysics Data System (ADS)

Tammareddi, Sriram; Sun, Guangyong; Li, Qing

2010-06-01

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.

Recanalization Results After Intracranial Stenting of Atherosclerotic Stenoses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blasel, Stella, E-mail: Stella.Blasel@kgu.de; Yuekzek, Zeynep; Kurre, Wiebke

2010-10-15

The purpose of this investigation was to provide a detailed description of the angiographic results after stenting of high-grade intracranial stenosis using balloon-expandable stents. Forty consecutive patients with symptomatic atherosclerotic intracranial stenosis >50% received endovascular treatment by placement of balloon-expandable stents using the concept of slight underdilation and strict avoidance of overdilation. Intra-arterial digital subtraction angiography images before and after stenting in the same projection were reviewed for pre- and post-therapeutic measurement of the degree of stenosis and evaluation of morphologic criteria like plaque coverage, stent apposition, patency of side branches, and signs of dissection or vasospasm. Stenting decreased themore » mean percentage stenosis from 76.2 (WASID criteria) to 20.8%. Residual stenosis ranged from 0 to 55% with residual stenosis >50% in two of 40 cases. Technical success rate was 95%. There were no major vessel complications, but minor abnormalities like incomplete stent apposition (8/40) or plaque coverage (7/40), incomplete filling of side branches (13/40), and minor dissections after stenting (2/40) were seen. One case with incomplete stent apposition and two cases with side branch compromise were associated with clinical symptoms. In conclusion, intracranial stenting with slight underdilation avoided major vessel complication and created reliable luminal gain. Suboptimal recanalization results were frequently detected and may be the source of neurological complications in individual cases.« less

Retrograde pyelography predicts retrograde ureteral stenting failure and reduces unnecessary stenting trials in patients with advanced non-urological malignant ureteral obstruction

PubMed Central

Kim, Sung Han; Park, Boram; Joo, Jungnam; Joung, Jae Young; Seo, Ho Kyung; Chung, Jinsoo; Lee, Kang Hyun

2017-01-01

Objective To evaluate predictive factors for retrograde ureteral stent failure in patients with non-urological malignant ureteral obstruction. Materials and methods Between 2005 and 2014, medical records of 284 malignant ureteral obstruction patients with 712 retrograde ureteral stent trials including 63 (22.2%) having bilateral malignant ureteral obstruction were retrospectively reviewed. Retrograde ureteral stent failure was defined as the inability to place ureteral stents by cystoscopy, recurrent stent obstruction within one month, or non-relief of azotemia within one week from the prior retrograde ureteral stent. The clinicopathological parameters and first retrograde pyelographic findings were analyzed to investigate the predictive factors for retrograde ureteral stent failure and conversion to percutaneous nephrostomy in multivariate analysis with a statistical significance of p < 0.05. Results Retrograde ureteral stent failure was detected in 14.1% of patients. The mean number of retrograde ureteral stent placements and indwelling duration of the ureteral stents were 2.5 ± 2.6 times and 8.6 ± 4.0 months, respectively. Multivariate analyses identified several specific RGP findings as significant predictive factors for retrograde ureteral stent failure (p < 0.05). The significant retrograde pyelographic findings included grade 4 hydronephrosis (hazard ratio 4.10, 95% confidence interval 1.39–12.09), irreversible ureteral kinking (hazard ratio 2.72, confidence interval 1.03–7.18), presence of bladder invasion (hazard ratio 4.78, confidence interval 1.81–12.63), and multiple lesions of ureteral stricture (hazard ratio 3.46, confidence interval 1.35–8.83) (p < 0.05). Conclusion Retrograde pyelography might prevent unnecessary and ineffective retrograde ureteral stent trials in patients with advanced non-urological malignant ureteral obstruction. PMID:28931043

Diagnostic accuracy of 64-slice multidetector CT angiography for detection of in-stent restenosis of vertebral artery ostium stents: comparison with conventional angiography.

PubMed

Lee, Youn Joo; Lim, Yeon Soo; Lim, Hyun Wook; Yoo, Won Jong; Choi, Byung Gil; Kim, Bum Soo

2014-10-01

There are very few reports assessing in-stent restenosis (ISR) after vertebral artery ostium (VAO) stents using multidetector computed tomography (MDCT). To compare the diagnostic accuracy of computed tomography angiography (CTA) using 64-slice MDCT with digital subtraction angiography (DSA) for detection of significant ISR after VAO stenting. The study evaluated 57 VAO stents in 57 patients (39 men, 18 women; mean age 64 years [range, 48-90 years]). All stents were scanned with a 64-slice MDCT scanner. Three sets of images were reconstructed with three different convolution kernels. Two observers who were blinded to the results of DSA assessed the diagnostic accuracy of CTA for detecting significant ISR (≥50% diameter narrowing) of VAO stents in comparison with DSA as the reference standard. The sensitivity, specificity, positive and negative predictive values, and accuracy were calculated. Of the 57 stents, 46 (81%) were assessable using CTA, while 11 (19%) were not. No stents with diameters ≤2.75 mm were assessable. DSA revealed 13 cases of significant ISR in all stents. The respective sensitivity, specificity, positive and negative predictive values, and accuracy were 92%, 82%, 60%, 97%, and 84% for all stents. On excluding the 11 non-assessable stents, the respective values were 88%, 95%, 78%, 97%, and 93%. Of the 46 CTA assessable stents, eight significant ISRs were diagnosed on DSA. Seven of eight patients with significant ISR by DSA were diagnosed correctly with CTA. The area under the receiver-operating characteristic curve (AUC) was 0.87 for all stents and 0.91 for assessable stents, indicating good to excellent agreement between CTA and DSA for detecting significant ISR after VAO stenting. Sixty-four-slice MDCT is a promising non-invasive method of assessing stent patency and can exclude significant ISR with high diagnostic values after VAO stenting. © The Foundation Acta Radiologica 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Role of metallic stents in benign esophageal stricture

NASA Astrophysics Data System (ADS)

Shim, Chan Sup

2012-10-01

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

Role of Montgomery T-tube stent for laryngotracheal stenosis.

PubMed

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.

Endoscopically placed nitinol stents for pediatric tracheal obstruction.

PubMed

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

Endoscopic stenting in bile duct cancer increases liver volume.

PubMed

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.

Percutaneous coronary angioscopy and stents

NASA Astrophysics Data System (ADS)

Heuser, Richard R.

1994-05-01

With the expanding array of therapies available for coronary intervention, the invasive cardiologist has many choices for treating a specific lesion in an individual patient. Certain types of lesions might respond more effectively with stents, particularly the rigid Palmax- Schatz device. Thrombus and dissection immediately following stent placement are associated with early occlusion, and the interventionist must be able to assess their presence pre- and post-stenting. Angiography is deficient in quantifying minimal disease and in defining lesion architecture and composition, as well as the plaque rupture and thrombosis associated with unstable angina. It is also imprecise in detecting dissection and thrombus. Intravascular ultrasound (IVUS) provides high-resolution images that delineate irregularities and other structures inside the lumen and within the vessel wall and surrounding tissues. Like angiography, IVUS has limited specificity for thrombus differentiation. Angioscopy is superior to angiography and IVUS in detecting thrombus and dissection. Angioscopy allows the clinician to assess the appearance of stent struts after deployment and at follow-up. This may aid in reducing acute complications as well as restenosis. Follow-up angioscopy of stents to detect thrombus or exposed struts may guide therapy in a patient who has clinical symptoms of restenosis.

Upper Gastrointestinal Stent Insertion in Malignant and Benign Disorders

PubMed Central

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

Impact of the Distance from the Stent Edge to the Residual Plaque on Edge Restenosis following Everolimus-Eluting Stent Implantation

PubMed Central