Dynamic simulation of stent deployment - effects of design, material and coating

NASA Astrophysics Data System (ADS)

Schiavone, A.; Zhao, L. G.; Abdel-Wahab, A. A.

2013-07-01

Dynamic finite-element simulations have been carried out to study the effects of cell design, material choice and drug eluting coating on the mechanical behaviour of stents during deployment. Four representative stent designs have been considered, i.e., Palmaz-Schatz, Cypher, Xience and Endeavor. The former two are made of stainless steel while the latter two made of Co-Cr alloy. Geometric model for each design was created using ProEngineer software, and then imported into Abaqus for simulation of the full process of stent deployment within a diseased artery. In all cases, the delivery system was based on the dynamic expansion of a polyurethane balloon under applied internal pressure. Results showed that the expansion is mainly governed by the design, in particular open-cell design (e.g. Endeavor) tends to have greater expansion than closed-cell design (e.g. Cypher). Dogboning effect was strong for slotted tube design (e.g. Palmaz-Schatz) but reduced significantly for sinusoidal design (e.g. Cypher). Under the same pressure, the maximum von Mises stress in the stent was higher for the open-cell designs and located mostly at the inner corners of each cell. For given deformation, stents made of Co-Cr alloys tend to experience higher stress level than those made of stainless steels, mainly due to the difference in material properties. For artery-plaque system, the maximum stress occurred on the stenosis and dogboning led to stress concentration at the ends of the plaque. The drug eluting coating affected the stent expansion by reducing the recoiling phenomenon considerably, but also raised the stress level on the stent due to property mismatch.

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

PubMed Central

Zhao, Nan; Zhu, Donghui

2016-01-01

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

Stent longitudinal strength assessed using point compression: insights from a second-generation, clinically related bench test.

PubMed

Ormiston, John A; Webber, Bruce; Ubod, Ben; White, Jonathon; Webster, Mark W I

2014-02-01

Stent longitudinal distortion, while infrequent, can lead to adverse clinical events. Our first bench comparison of susceptibility of different stent designs to distortion applied force to the entire circumference of the proximal stent hoop. The test increased understanding of stent design and led to recommendations for design change in some. Our second-generation test more closely mimics clinical scenarios by applying force to a point on the proximal hoop of a malapposed stent. Each 3-mm-diameter stent was secured in a test apparatus so that its proximal 5 mm was malapposed in a 3.5-mm tube. An instron applied force to the proximal hoop of each of 5 examples of each of 6 stent designs using a narrow rod so that force applied and distance compressed could be measured. Hoops on the side of the force were pushed together, became malapposed, and obstructed the lumen. In addition, the proximal stent hoop tilted causing malapposition, the contralateral side of the stent from the applied force causing lumen obstruction. This second-generation, more clinically relevant test showed the Biomatrix Flex was the most resistant to deformation and the Element the most easily deformed. The addition of more connectors between the proximal hoops in the Promus Premier design has reduced the potential for distortion when compared with the Element, so that distortion was similar to the Vision, Multi-Link 8, and Integrity designs. The test also provided insight into the way in which stents are likely to distort in clinical practice.

Repeated unit cell (RUC) approach for pure bending analysis of coronary stents.

PubMed

Ju, Feng; Xia, Zihui; Zhou, Chuwei

2008-08-01

Flexibility is one of the key properties of coronary stents. The objective of this paper is to characterize the bending behaviour of stents through finite element analysis with repeated unit cell (RUC) models. General periodic boundary conditions for the RUC under the pure bending condition are formulated. It is found that the proposed RUC approach can provide accurate numerical results of bending behaviour of stents with much less computational costs. Bending stiffness, post-yield bending behaviour and the relationship between moment and bending curvature are investigated for Palmaz-Schatz stents and stents with the V- and S-shaped links. It is found that the effect of link geometry on the bending behaviour of stent is significant. The behaviour of stents subjected to cyclic bending is also investigated.

[Proposed model of vascular trauma by mean of mechanical characterization of endovascular prostheses (stents) based on structural analysis by FEA].

PubMed

Bustamante, John; Uribe, Pablo; Sosa, Mauricio; Valencia, Raúl

2016-01-01

The accumulated evidence on angioplasty techniques with stents has raised a controversy about the factors that influence the final vascular response. Indeed, several studies have shown there might be re-stenosis between 30% to 40% about 6 months after placement, relating to the design of the device as one of the main causes. This paper proposes the functional characterization of endovascular stents, analyzing its mechanical influence in the vascular system and predicting implicit traumatic factors in the vessel. A structural analysis was made for several computational models of endovascular stents using Finite Element Analysis in order to predict the mechanical behavior and the vascular trauma. In this way, the stents were considered as tubular devices composed of multiple links under radial pressure loads, reflecting stress concentration effects. The analysis allowed to visualize how the geometry of stents is adjusted under several load conditions, in order to obtain the response of "solid-solid" interaction between the stent and the arterial wall. Thus, an analysis was performed in order to calculate stress, and a conceptual model that explains its mechanical impact on the stent-vessel interaction, was raised, to infer on the functionality from the design of the devices. The proposed conceptual model allows to determine the relationship between the conditions of mechanical interaction of the stents, and warns about the effects in what would be the operation of the device on the vascular environment. Copyright © 2016 Instituto Nacional de Cardiología Ignacio Chávez. Publicado por Masson Doyma México S.A. All rights reserved.

New Variable Porosity Flow Diverter (VPOD) Stent Design for Treatment of Cerebrovascular Aneurysms

PubMed Central

Ionita, Ciprian; Baier, Robert; Rudin, Stephen

2012-01-01

Using flow diverting Stents for intracranial aneurysm repair has been an area of recent active research. While current commercial flow diverting stents rely on a dense mesh of braided coils for flow diversion, our group has been developing a method to selectively occlude the aneurysm neck, without endangering nearby perforator vessels. In this paper, we present a new method of fabricating the low porosity patch, a key element of such asymmetric vascular stents (AVS). PMID:22254507

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.

Finite element analysis of the biomechanical interaction between coronary sinus and proximal anchoring stent in coronary sinus annuloplasty

PubMed Central

Pham, Thuy; Deherrera, Milton; Sun, Wei

2013-01-01

Recent clinical studies of the percutaneous transvenous mitral annuloplasty (PTMA) devices have shown a short-term reduction of mitral regurgitation (MR) after implantation. However, adverse events associated with the devices such as compression and perforation of vessel branches, device migration and fracture were reported. In this study, a finite element analysis was performed to investigate the biomechanical interaction between the proximal anchor stent of a PTMA device and the coronary sinus (CS) vessel in three steps including i) the stent release and contact with the CS wall, ii) the axial pull at the stent connector and iii) the pressure inflation of the vessel wall. To investigate the impact of the material properties of tissues and stents on the interactive responses, the CS vessel was modeled with human and porcine material properties, and the proximal stent was modeled with two different Nitinol materials with one being stiffer than the other. The results indicated that the vessel wall stresses and contact forces imposed by the stents were much higher in human than porcine models. However, the mechanical differences induced by the two stent types were relatively small. The softer stent exhibited a better fatigue safety factor when deployed in the human model than in the porcine model. These results underscored the importance of the CS tissue mechanical properties. Higher vessel wall stress and stent radial force were obtained in human model than those in porcine model, which also brought up questions as to the validity of using porcine model to assess device mechanical function. The quantification of these biomechanical interactions can offer scientific insight into the development and optimization of PTMA device design. PMID:23405942

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.

Virtual evaluation of stent graft deployment: a validated modeling and simulation study.

PubMed

De Bock, S; Iannaccone, F; De Santis, G; De Beule, M; Van Loo, D; Devos, D; Vermassen, F; Segers, P; Verhegghe, B

2012-09-01

The presented study details the virtual deployment of a bifurcated stent graft (Medtronic Talent) in an Abdominal Aortic Aneurysm model, using the finite element method. The entire deployment procedure is modeled, with the stent graft being crimped and bent according to the vessel geometry, and subsequently released. The finite element results are validated in vitro with placement of the device in a silicone mock aneurysm, using high resolution CT scans to evaluate the result. The presented work confirms the capability of finite element computer simulations to predict the deformed configuration after endovascular aneurysm repair (EVAR). These simulations can be used to quantify mechanical parameters, such as neck dilations, radial forces and stresses in the device, that are difficult or impossible to obtain from medical imaging. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characterization of compression behaviors of fully covered biodegradable polydioxanone biliary stent for human body: A numerical approach by finite element model.

PubMed

Liu, Yanhui; Zhang, Peihua

2016-09-01

This paper presents a study of the compression behaviors of fully covered biodegradable polydioxanone biliary stents (FCBPBs) developed for human body by finite element method. To investigate the relationship between the compression force and structure parameter (monofilament diameter and braid-pin number), nine numerical models based on actual biliary stent were established, the simulation and experimental results are in good agreement with each other when calculating the compression force derived from both experiment and simulation results, indicating that the simulation results can be provided a useful reference to the investigation of biliary stents. The stress distribution on FCBPBSs was studied to optimize the structure of FCBPBSs. In addition, the plastic dissipation analysis and plastic strain of FCBPBSs were obtained via the compression simulation, revealing the structure parameter effect on the tolerance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation on Compressive Characteristics of Medical Stents Applied by Mesh Structures

NASA Astrophysics Data System (ADS)

Hirayama, Kazuki; He, Jianmei

2017-11-01

There are concerns about strength reduction and fatigue fracture due to stress concentration in currently used medical stents. To address these problems, meshed stents applied by mesh structures were interested for achieving long life and high strength perfromance of medical stents. The purpose of this study is to design basic mesh shapes to obatin three dimensional (3D) meshed stent models for mechanical property evaluation. The influence of introduced design variables on compressive characteristics of meshed stent models are evaluated through finite element analysis using ANSYS Workbench code. From the analytical results, the compressive stiffness are changed periodically with compressive directions, average results need to be introduced as the mean value of compressive stiffness of meshed stents. Secondly, compressive flexibility of meshed stents can be improved by increasing the angle proportional to the arm length of the mesh basic shape. By increasing the number of basic mesh shapes arranged in stent’s circumferential direction, compressive rigidity of meshed stent tends to be increased. Finaly reducing the mesh line width is found effective to improve compressive flexibility of meshed stents.

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 higher performance and biocompatibility can intrinsically reduce stent failure rates. The present study demonstrates the advantages of a novel material, named bulk metallic glass (BMG), over the benchmarked 316L stainless steel through experimental methods and computational simulations. It raises the curtain of new research endeavors on BMGs as competitive alternatives for stent applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mechanical design of an intracranial stent for treating cerebral aneurysms.

PubMed

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

2010-11-01

Endovascular treatment of cerebral aneurysms using stents has advanced markedly in recent years. Mechanically, a cerebrovascular stent must be very flexible longitudinally and have low radial stiffness. However, no study has examined the stress distribution and deformation of cerebrovascular stents using the finite element method (FEM) and experiments. Stents can have open- and closed-cell structures, and open-cell stents are used clinically in the cerebrovasculature because of their high flexibility. However, the open-cell structure confers a risk of in-stent stenosis due to protrusion of stent struts into the normal parent artery. Therefore, a flexible stent with a closed-cell structure is required. To design a clinically useful, highly flexible, closed-cell stent, one must examine the mechanical properties of the closed-cell structure. In this study, we investigated the relationship between mesh patterns and the mechanical properties of closed-cell stents. Several mesh patterns were designed and their characteristics were studied using numerical simulation. The results showed that the bending stiffness of a closed-cell stent depends on the geometric configuration of the stent cell. It decreases when the stent cell is stretched in the circumferential direction. Mechanical flexibility equal to an open-cell structure was obtained in a closed-cell structure by varying the geometric configuration of the stent cell. Copyright © 2010 IPEM. Published by Elsevier Ltd. All rights reserved.

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.

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

PubMed

Hsiao, Hao-Ming; Yin, Ming-Ting

2014-02-01

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

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.

A numerical study on the effect of geometrical parameters and loading profile on the expansion of stent.

PubMed

Beigzadeh, Borhan; Mirmohammadi, Seyed Alireza; Ayatollahi, Majid Reza

2017-01-01

Stenting has been proposed as an effective treatment to restore blood flow in obstructed arteries by plaques. Although several modified designs for stents have been suggested, most designs have the risk of disturbing blood flow. The main objective is to propose a stent design to attain a uniform lumen section after stent deployment. Mechanical response of five different designs of J & J Palmaz-Schatz stent with the presence of plaque and artery are investigated; four stents have variable strut thickness of different magnitudes and the rest one is a uniform-strut-thickness stent. Nonlinear finite element is employed to simulate the expansion procedure of the intended designs using ABAQUS explicit. The stent design whose first cell thickness linearly increases by 35 percent, exhibits the best performance, that is it has the lowest recoiling and stress induced in the intima for a given lumen gain. It also enjoys the minimal discrepancy between the final at the distal and proximal ends. A uniform widened artery can be achieved by using the stent design with 35 percent increase in its first cell, which provides the possibility to prevent from disturbing blood flow and consequently post-operation complications.

A computational study of crimping and expansion of bioresorbable polymeric stents

NASA Astrophysics Data System (ADS)

Qiu, T. Y.; Song, M.; Zhao, L. G.

2018-05-01

This paper studied the mechanical performance of four bioresorbable PLLA stents, i.e., Absorb, Elixir, Igaki-Tamai and RevaMedical, during crimping and expansion using the finite element method. Abaqus CAE was used to create the geometrical models for the four stents. A tri-folded balloon was created using NX software. For the stents, elastic-plastic behaviour was used, with hardening implemented by considering the increase of yield stress with the plastic strain. The tri-folded balloon was treated as linear elastic. To simulate the crimping of stents, a set of 12 rigid plates were generated around the stents with a radially enforced displacement. During crimping, the stents were compressed from a diameter of 3 mm to 1.2 mm, with the maximum stress developed at both inner and outer sides of the U-bends. During expansion, the stent inner diameter increased to 3 mm at the peak pressure and then recoiled to different final diameters after balloon deflation due to different stent designs. The maximum stress was found again at the U-bends of stents. Diameter change, recoiling effect and radial strength/stiffness were also compared for the four stents to assess the effect of design variation on stent performance. The effect of loading rate on stent deformation was also simulated by considering the time-dependent plastic behaviour of polymeric material.

A computational study of crimping and expansion of bioresorbable polymeric stents

NASA Astrophysics Data System (ADS)

Qiu, T. Y.; Song, M.; Zhao, L. G.

2017-10-01

This paper studied the mechanical performance of four bioresorbable PLLA stents, i.e., Absorb, Elixir, Igaki-Tamai and RevaMedical, during crimping and expansion using the finite element method. Abaqus CAE was used to create the geometrical models for the four stents. A tri-folded balloon was created using NX software. For the stents, elastic-plastic behaviour was used, with hardening implemented by considering the increase of yield stress with the plastic strain. The tri-folded balloon was treated as linear elastic. To simulate the crimping of stents, a set of 12 rigid plates were generated around the stents with a radially enforced displacement. During crimping, the stents were compressed from a diameter of 3 mm to 1.2 mm, with the maximum stress developed at both inner and outer sides of the U-bends. During expansion, the stent inner diameter increased to 3 mm at the peak pressure and then recoiled to different final diameters after balloon deflation due to different stent designs. The maximum stress was found again at the U-bends of stents. Diameter change, recoiling effect and radial strength/stiffness were also compared for the four stents to assess the effect of design variation on stent performance. The effect of loading rate on stent deformation was also simulated by considering the time-dependent plastic behaviour of polymeric material.

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.

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.

Scanning Electron Microscopic Features of Nasolacrimal Silastic Stents Retained for Prolong Durations Following Dacryocystorhinostomy.

PubMed

Ali, Mohammad Javed; Baig, Farhana; Lakshman, Mekala; Naik, Milind N

2016-01-01

The aims of this study were to examine the scanning electron microscopic features of silastic nasolacrimal duct stents retained for long durations following a dacryocystorhinostomy. A prospective interventional study was performed on stents retrieved from patients who were lost to follow up after a dacryocystorhinostomy with Crawford stent insertion. Long duration was defined as stents retrieved at a minimum of 1 year following a dacryocystorhinostomy. None of the patients had any evidence of postoperative infection. After removal, the stent segments were subjected to biofilm and physical deposit analysis using standard protocols of scanning electron microscopy. These stent segments were compared against sterile stents which acted as controls. A total of 7 stents were studied. Five were consecutive patient samples, and 2 were sterile stents. All the 5 stents were retrieved from patients who were lost to follow up for a minimum of 12 months following surgery. The mean duration of intubation at retrieval was 21 months. All the stents demonstrated evidence of biofilm formation and physical deposits. However, as the duration of retention increased, the deposits and biofilms were noted to be progressively denser, multilayered and extensive. Certain areas demonstrated thick biofilm integration with the deposits. Polymicrobial communities were noted within the exopolysaccharide matrix. This is the first study to exclusively report on scanning electron microscopic features of lacrimal stents retained for long durations. Further studies on physical elements within the deposits and protein analysis would provide more insights into stent-tissue interactions.

DUrable polymer-based sTent CHallenge of Promus ElemEnt versus ReSolute integrity (DUTCH PEERS): rationale and study design of a randomized multicenter trial in a Dutch all-comers population.

PubMed

Tandjung, Kenneth; Basalus, Mounir W Z; Sen, Hanim; Jessurun, Gillian A J; Danse, Peter W; Stoel, Martin; Linssen, Gerard C M; Derks, Anita; van Loenhout, Ton T; Nienhuis, Mark B; Hautvast, Raymond W M; von Birgelen, Clemens

2012-04-01

Drug-eluting stents (DES) are increasingly used for the treatment of coronary artery disease. An optimized DES performance is desirable to successfully treat various challenging coronary lesions in a broad population of patients. In response to this demand, third-generation DES with an improved deliverability were developed. Promus Element (Boston Scientific, Natick, MA) and Resolute Integrity (Medtronic Vascular, Santa Rosa, CA) are 2 novel third-generation DES for which limited clinical data are available. Accordingly, we designed the current multicenter study to investigate in an all-comers population whether the clinical outcome is similar after stenting with Promus Element versus Resolute Integrity. DUTCH PEERS is a multicenter, prospective, single-blinded, randomized trial in a Dutch all-comers population. Patients with all clinical syndromes who require percutaneous coronary interventions with DES implantation are eligible. In these patients, the type of DES implanted will be randomized in a 1:1 ratio between Resolute Integrity versus Promus Element. The trial is powered based on a noninferiority hypothesis. For each stent arm, 894 patients will be enrolled, resulting in a total study population of 1,788 patients. The primary end point is the incidence of target vessel failure at 1-year follow-up. DUTCH PEERS is the first randomized multicenter trial with a head-to-head comparison of Promus Element and Resolute Integrity to investigate the safety and efficacy of these third-generation DES. Copyright © 2012 Mosby, Inc. All rights reserved.

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.

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.

Feasibility of using bulk metallic glass for self-expandable stent applications.

PubMed

Praveen Kumar, Gideon; Jafary-Zadeh, Mehdi; Tavakoli, Rouhollah; Cui, Fangsen

2017-10-01

Self-expandable stents are widely used to restore blood flow in a diseased artery segment by keeping the artery open after angioplasty. Despite the prevalent use of conventional crystalline metallic alloys, for example, nitinol, to construct self-expandable stents, new biomaterials such as bulk metallic glasses (BMGs) are being actively pursued to improve stent performance. Here, we conducted a series of analyses including finite element analysis and molecular dynamics simulations to investigate the feasibility of using a prototypical Zr-based BMG for self-expandable stent applications. We model stent crimping of several designs for different percutaneous applications. Our results indicate that BMG-based stents with diamond-shaped crowns suffer from severe localization of plastic deformation and abrupt failure during crimping. As a possible solution, we further illustrate that such abrupt failure could be avoided in BMG-based stents without diamond shape crowns. This work would open a new horizon for a quest toward exploiting superior mechanical and functional properties of metallic glasses to design future stents. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1874-1882, 2017. © 2016 Wiley Periodicals, Inc.

A Feasibility Study of a New Unibody Branched Stent Graft Applied to Reconstruct the Canine Aortic Arch.

PubMed

Li, W; Zhai, S; Xu, K; Li, Q; Zhong, H; Li, T; Zhang, Z

2018-06-01

The aim was to evaluate the feasibility and safety of a new unibody branched stent graft for the reconstruction of the canine aortic arch. The unibody branched stent grafts included single branched stent grafts and double branched stent grafts. The main stent graft and branched limbs were sutured together. The branched stent grafts were folded into the introducer system, which consisted of a double channel catheter, a detachable sleeve, and an introducer sheath. The branched stent grafts were introduced and deployed into the aortic arch by the delivery system. Twenty adult mongrel dogs were used for the experiments. Ten dogs were implanted with single branched stent grafts; the other 10 were implanted with double branched stent grafts. The surviving animals were followed up for 3 months. Computed tomography angiography (CTA) was performed to observe the status of the branched stent grafts. All the unibody branched stent grafts were successfully implanted into the canine aortic arches. The technical success rate was 100%. There was no cerebral infarction, paraplegia or incision infection. CTA showed that all the branched stent grafts were patent; there was no endoleak or stent migration. The unibody branched stent graft system could be used to reconstruct the aortic arch. The animal experimental procedures demonstrated the safety and feasibility of the unibody branched stent graft system. Copyright © 2018 European Society for Vascular Surgery. Published by Elsevier B.V. All rights reserved.

Design Investigation on Applicable Mesh Structures for Medical Stent Applications

NASA Astrophysics Data System (ADS)

Asano, Shoji; He, Jianmei

2017-11-01

In recent years, utilization of medical stents is one of effective treatments for stenosis and occlusion occurring in a living body’s lumen indispensable for maintenance of human life such as superficial femoral artery (SFA) occlusion. However, there are concerns about the occurrence of fatigue fractures caused by stress concentrations, neointimal hyperplasia and the like due to the shape structure and the manufacturing method in the conventional stents, and a stent having high strength and high flexibility is required. Therefore, in this research, applicable mesh structures for medical stents based on the design concepts of high strength, high flexibility are interested to solve various problem of conventional stent. According to the shape and dimensions of SFA occlusion therapy stent and indwelling delivery catheter, shape design of the meshed stent are performed using 3-dimensional CAD software Solid Works first. Then analytical examination on storage characteristics and compression characteristics of such mesh structure applied stent models were carried out through finite element analysis software ANSYS Workbench. Meshed stent models with higher strength and higher flexibility with integral molding are investigated analytically. It was found that the storage characteristics and compression characteristics of meshed stent modles are highly dependent on the basic mesh shapes with same surface void ratio. Trade-off relationship between flexibility and storage characteristics is found exited, it is required to provide appropriate curvatures during basic mesh shape design.

A strain-mediated corrosion model for bioabsorbable metallic stents.

PubMed

Galvin, E; O'Brien, D; Cummins, C; Mac Donald, B J; Lally, C

2017-06-01

This paper presents a strain-mediated phenomenological corrosion model, based on the discrete finite element modelling method which was developed for use with the ANSYS Implicit finite element code. The corrosion model was calibrated from experimental data and used to simulate the corrosion performance of a WE43 magnesium alloy stent. The model was found to be capable of predicting the experimentally observed plastic strain-mediated mass loss profile. The non-linear plastic strain model, extrapolated from the experimental data, was also found to adequately capture the corrosion-induced reduction in the radial stiffness of the stent over time. The model developed will help direct future design efforts towards the minimisation of plastic strain during device manufacture, deployment and in-service, in order to reduce corrosion rates and prolong the mechanical integrity of magnesium devices. The need for corrosion models that explore the interaction of strain with corrosion damage has been recognised as one of the current challenges in degradable material modelling (Gastaldi et al., 2011). A finite element based plastic strain-mediated phenomenological corrosion model was developed in this work and was calibrated based on the results of the corrosion experiments. It was found to be capable of predicting the experimentally observed plastic strain-mediated mass loss profile and the corrosion-induced reduction in the radial stiffness of the stent over time. To the author's knowledge, the results presented here represent the first experimental calibration of a plastic strain-mediated corrosion model of a corroding magnesium stent. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A Finite Element Study on Variations in Mass Transport in Stented Porcine Coronary Arteries Based on Location in the Coronary Arterial Tree

PubMed Central

Keyes, Joseph T.; Simon, Bruce R.; Vande Geest, Jonathan P.

2013-01-01

Drug-eluting stents have a significant clinical advantage in late-stage restenosis due to the antiproliferative drug release. Understanding how drug transport occurs between coronary arterial locations can better help guide localized drug treatment options. Finite element models with properties from specific porcine coronary artery sections (left anterior descending (LAD), right (RCA); proximal, middle, distal regions) were created for stent deployment and drug delivery simulations. Stress, strain, pore fluid velocity, and drug concentrations were exported at different time points of simulation (0–180 days). Tests indicated that the highest stresses occurred in LAD sections. Higher-than-resting homeostatic levels of stress and strain existed at upwards of 3. mm away from the stented region, whereas concentration of species only reached 2.7 mm away from the stented region. Region-specific concentration showed 2.2 times higher concentrations in RCA artery sections at times corresponding to vascular remodeling (peak in the middle segment) compared to all other segments. These results suggest that wall transport can occur differently based on coronary artery location. Awareness of peak growth stimulators and where drug accumulation occurs in the vasculature can better help guide local drug delivery therapies. PMID:23699720

The modified pancreatic stent system for prevention of post-ERCP pancreatitis: a case-control study.

PubMed

Zhang, Cheng; Yang, Yu-Long; Ma, Yue-Feng; Zhang, Hong-Wei; Li, Jing-Yi; Lin, Mei-Ju; Shi, Li-Jun; Qi, Chun-Chun

2017-10-18

Prophylactic pancreatic stents after endoscopic retrograde cholangiopancreatography (ERCP) can help prevent post-ERCP pancreatitis. However most of the pancreatic stents need to be removed by another ERCP. The aim of this observational study was to investigate the feasibility and effectiveness of the modified pancreatic stent system for prevention of post-ERCP pancreatitis. From November 2013 to November 2015, a total of 230 patients who had prophylactic pancreatic stent placed for prevention of post-ERCP pancreatitis at a single institution were identified and stratified. In this case-control design, 150 patients received an ordinary pancreatic stent, and 80 patients received the modified pancreatic stent. The main outcome measures were the difficulty level and complications of pancreatic stent placement and extraction between the two groups. In ordinary group, the average time of pancreatic stent and nasal biliary drainage placement was 3.5 ± 0.6 min. There were 13 cases of stent proximal migration (8.7%), 20 cases of stent spontaneous abscission (13.3%), 5 cases of acute pancreatitis (3.3%) (2 cases for stent abscission) and 7 cases of hyperamylasemia (4.7%) after ERCP. One hundred thirty patients received extra duodenoscope (86.7%) to remove the stent, and 4 cases had acute pancreatitis and 5 patients had hyperamylasemia after removing the proximal migratory stents. In modified group, the average time of pancreatic stent system placement was 4.9 ± 0.7 min, but there was only one case of stent abscission (1.3%), 2 cases of acute pancreatitis (2.5%) and 3 cases of hyperamylasemia (3.8%). The new pancreatic stents were removed directly under x-ray without complication. The modified pancreatic stent system has the same effect of preventing post-ERCP pancreatitis, lower rate of stents proximal migration and spontaneous abscission, and the advantage of easier removed compared with ordinary pancreatic stent.

In Vitro Biocompatibility and Endothelialization of Novel Magnesium-Rare Earth Alloys for Improved Stent Applications

PubMed Central

Zhao, Nan; Watson, Nevija; Xu, Zhigang; Chen, Yongjun; Waterman, Jenora; Sankar, Jagannathan; Zhu, Donghui

2014-01-01

Magnesium (Mg) based alloys are the most advanced cardiovascular stent materials. This new generation of stent scaffold is currently under clinical evaluation with encouraging outcomes. All these Mg alloys contain a certain amount of rare earth (RE) elements though the exact composition is not yet disclosed. RE alloying can usually enhance the mechanical strength of different metal alloys but their toxicity might be an issue for medical applications. It is still unclear how RE elements will affect the magnesium (Mg) alloys intended for stent materials as a whole. In this study, we evaluated MgZnCaY-1RE, MgZnCaY-2RE, MgYZr-1RE, and MgZnYZr-1RE alloys for cardiovascular stents applications regarding their mechanical strength, corrosion resistance, hemolysis, platelet adhesion/activation, and endothelial biocompatibility. The mechanical properties of all alloys were significantly improved. Potentiodynamic polarization showed that the corrosion resistance of four alloys was at least 3–10 times higher than that of pure Mg control. Hemolysis test revealed that all the materials were non-hemolytic while little to moderate platelet adhesion was found on all materials surface. No significant cytotoxicity was observed in human aorta endothelial cells cultured with magnesium alloy extract solution for up to seven days. Direct endothelialization test showed that all the alloys possess significantly better capability to sustain endothelial cell attachment and growth. The results demonstrated the promising potential of these alloys for stent material applications in the future. PMID:24921251

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.

Impact of stent mis-sizing and mis-positioning on coronary fluid wall shear and intramural stress

PubMed Central

Chen, Henry Y.; Koo, Bon-Kwon; Bhatt, Deepak L.

2013-01-01

Stent deployments with geographical miss (GM) are associated with increased risk of target-vessel revascularization and periprocedural myocardial infarction. The aim of the current study was to investigate the underlying biomechanical mechanisms for adverse events with GM. The hypothesis is that stent deployment with GM [longitudinal GM, or LGM (i.e., stent not centered on the lesion); or radial GM, RGM (i.e., stent oversizing)] results in unfavorable fluid wall shear stress (WSS), WSS gradient (WSSG), oscillatory shear index (OSI), and intramural circumferential wall stress (CWS). Three-dimensional computational models of stents and plaque were created using a computer-assisted design package. The models were then solved with validated finite element and computational fluid dynamic packages. The dynamic process of large deformation stent deployment was modeled to expand the stent to the desired vessel size. Stent deployed with GM resulted in a 45% increase in vessel CWS compared with stents that were centered and fully covered the lesion. A 20% oversized stent resulted in 72% higher CWS than a correct sized stent. The linkages between the struts had much higher stress than the main struts (i.e., 180 MPa vs. 80 MPa). Additionally, LGM and RGM reduced endothelial WSS and increased WSSG and OSI. The simulations suggest that both LGM and RGM adversely reduce WSS but increase WSSG, OSI, and CWS. These findings highlight the potential mechanical mechanism of the higher adverse events and underscore the importance of stent positioning and sizing for improved clinical outcome. PMID:23722708

Immediate and late clinical and angiographic outcomes after GFX coronary stenting: is high-pressure balloon dilatation necessary?

PubMed

Park, S W; Hong, M K; Lee, C W; Kim, J J; Park, H K; Cho, G Y; Kang, D H; Song, J K; Park, S J

2000-08-01

The GFX stent is a balloon-expandable stent made of sinusoidal element of stainless steel. The adjunct high-pressure balloon dilatations were usually recommended in routine stenting procedure. The aim of this study was to evaluate the immediate and long-term clinical and angiographic outcomes and to investigate the necessity of high-pressure balloon dilatation during GFX stenting. In all, 172 consecutive patients underwent single 12 or 18 mm GFX stent implantation in 188 native coronary lesions. Two types of stenting technique were used: (1) stent size of a final stent-to-artery ratio of 1:1 (inflation pressure > 10 atm, high-pressure group), and (2) stent size of 0.5 mm bigger than reference vessel (inflation pressure < or = 10 atm, low-pressure group). The adjunct high-pressure balloon dilatations were performed only in cases of suboptimal results. The adjunct high-pressure balloon dilatation was required in 11 of 83 lesions (13%) in the high-pressure group and in 7 of 105 lesions (7%) in the low-pressure group (p = 0.203). Procedural success rate was 100%. There were no significant differences of in-hospital and long-term clinical events between the two groups. The overall angiographic restenosis rate was 17.7%; 18.4% in the high-pressure group and 17.1% in the low-pressure group (p = 0.991). The GFX stent is a safe and effective device with a high procedural success rate and favorable late clinical outcome for treatment of native coronary artery disease. Further randomized trials may be needed to compare stenting techniques in GFX stent implantation.

Surgical stent planning: simulation parameter study for models based on DICOM standards.

PubMed

Scherer, S; Treichel, T; Ritter, N; Triebel, G; Drossel, W G; Burgert, O

2011-05-01

Endovascular Aneurysm Repair (EVAR) can be facilitated by a realistic simulation model of stent-vessel-interaction. Therefore, numerical feasibility and integrability in the clinical environment was evaluated. The finite element method was used to determine necessary simulation parameters for stent-vessel-interaction in EVAR. Input variables and result data of the simulation model were examined for their standardization using DICOM supplements. The study identified four essential parameters for the stent-vessel simulation: blood pressure, intima constitution, plaque occurrence and the material properties of vessel and plaque. Output quantities such as radial force of the stent and contact pressure between stent/vessel can help the surgeon to evaluate implant fixation and sealing. The model geometry can be saved with DICOM "Surface Segmentation" objects and the upcoming "Implant Templates" supplement. Simulation results can be stored using the "Structured Report". A standards-based general simulation model for optimizing stent-graft selection may be feasible. At present, there are limitations due to specification of individual vessel material parameters and for simulating the proximal fixation of stent-grafts with hooks. Simulation data with clinical relevance for documentation and presentation can be stored using existing or new DICOM extensions.

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.

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

PubMed

Turco, Mark A

2011-05-01

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

Numerical investigations of the mechanical properties of braided vascular stents.

PubMed

Fu, Wenyu; Xia, Qixiao; Yan, Ruobing; Qiao, Aike

2018-01-01

Braided stents, such as Pipeline Embolization Device (PED; ev3 Neurovascular, Irvine, CA, USA), are commonly used to treat cerebral aneurysms. However, little information is available on the compression and bending characteristics of such stents. This paper investigates how geometrical parameters of braided stents influence their radial compression and bending characteristics. Six groups of braided stent models with different braiding angles, numbers of wires and wire diameters are constructed. Parametric analyses of these models are conducted using Abaqus/Explicit software. The numerical results of a finite element analysis are validated by comparison with data of theoretical analysis. The results show that the radial stiffness is not uniform along the longitudinal direction of the stent. When the braiding angle increases from 30° to 75°, the minimum radial deformation decreases from 0.85 mm to 0.0325 mm (at a pressure of 500 Pa, for 24 braided wires). When the wire diameter increases from 0.026 mm to 0.052 mm, the minimum radial deformation decreases from 0.65 mm to 0.055 mm (at a pressure of 500 Pa and a braiding angle of 60°, for 24 braided wires). Frictions don't affect stent diameter and its axial length when braided stent is crimping, but the friction must be considered when it is related to the radial pressure required for compression the braided stent. Compared with commonly used intracranial stents, a braided stent with geometrical parameters close to PED stent has a smaller radial stiffness but a considerably greater longitudinal flexibility. The results of this analysis of braided stents can help in the design and selection of flow diverter stents for clinical treatment of cerebral aneurysms.

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.

Evaluation of a Bioabsorbable Self-Expandable Vein Stent-Base Made of Poly(L-lactide) In Vitro and In Vivo.

PubMed

Løvdal, Alexandra Liv Vest; Calve, Sarah; Yang, Shuo; Van Alstine, William; Binkert, Christoph A; Klausen, Kasper

2017-01-01

This study was designed to evaluate performance and tissue response to a self-expandable bioabsorbable vein stent-base cut from a tube with enhanced stiffness and strength in vitro and in vivo. A diamond-shaped stent-base was cut from a sequential biaxially strained poly(L-lactide) (PLLA) tube for optimized performance. The performance of the stent-base was evaluated in a finite element analysis model, and validation was attempted in vitro through a cyclic flat-plate compression and radial force measurement. The performance of the stent-base was tested in vivo using 3 sheep with 2 implants each for 2 and 3½ weeks, respectively. In vitro the stent-base showed an elliptical deformation but no fractures. In vivo the stent-base showed adequate radial force and no migration. All implanted stent-bases showed multiple fractures not only at the predicted stress zones but at all connecting points. Fragments of the caudal stent-base stayed in the vein wall indicating sufficient tissue coverage to avoid embolization of the fractured stent pieces, whereas fragments from the cranial device remaining were few. Neointima formation was confirmed histologically at 2 and 3½ weeks. A bioabsorbable self-expandable stent-base made from PLLA for large veins seems feasible, but over time, the PLLA used in this study appears too stiff and lacks the sufficient flexibility to move with the vena cava, causing multiple fractures.

Evaluation of a Bioabsorbable Self-Expandable Vein Stent-Base Made of Poly(l-lactide) In Vitro and In Vivo

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

Løvdal, Alexandra Liv Vest, E-mail: alvlo@nanotech.dtu.dk; Calve, Sarah; Yang, Shuo

PurposeThis study was designed to evaluate performance and tissue response to a self-expandable bioabsorbable vein stent-base cut from a tube with enhanced stiffness and strength in vitro and in vivo.MethodsA diamond-shaped stent-base was cut from a sequential biaxially strained poly(l-lactide) (PLLA) tube for optimized performance. The performance of the stent-base was evaluated in a finite element analysis model, and validation was attempted in vitro through a cyclic flat-plate compression and radial force measurement. The performance of the stent-base was tested in vivo using 3 sheep with 2 implants each for 2 and 3½ weeks, respectively.ResultsIn vitro the stent-base showed anmore » elliptical deformation but no fractures. In vivo the stent-base showed adequate radial force and no migration. All implanted stent-bases showed multiple fractures not only at the predicted stress zones but at all connecting points. Fragments of the caudal stent-base stayed in the vein wall indicating sufficient tissue coverage to avoid embolization of the fractured stent pieces, whereas fragments from the cranial device remaining were few. Neointima formation was confirmed histologically at 2 and 3½ weeks.ConclusionA bioabsorbable self-expandable stent-base made from PLLA for large veins seems feasible, but over time, the PLLA used in this study appears too stiff and lacks the sufficient flexibility to move with the vena cava, causing multiple fractures.« less

An Efficient Finite Element Framework to Assess Flexibility Performances of SMA Self-Expandable Carotid Artery Stents

PubMed Central

Ferraro, Mauro; Auricchio, Ferdinando; Boatti, Elisa; Scalet, Giulia; Conti, Michele; Morganti, Simone; Reali, Alessandro

2015-01-01

Computer-based simulations are nowadays widely exploited for the prediction of the mechanical behavior of different biomedical devices. In this aspect, structural finite element analyses (FEA) are currently the preferred computational tool to evaluate the stent response under bending. This work aims at developing a computational framework based on linear and higher order FEA to evaluate the flexibility of self-expandable carotid artery stents. In particular, numerical simulations involving large deformations and inelastic shape memory alloy constitutive modeling are performed, and the results suggest that the employment of higher order FEA allows accurately representing the computational domain and getting a better approximation of the solution with a widely-reduced number of degrees of freedom with respect to linear FEA. Moreover, when buckling phenomena occur, higher order FEA presents a superior capability of reproducing the nonlinear local effects related to buckling phenomena. PMID:26184329

A rapid-exchange monorail stent system for salvage of failing femoropopliteal bypass grafts.

PubMed

Jahnke, Thomas; Brossmann, Joachim; Walluscheck, Knut; Heller, Martin; Müller-Hülsbeck, Stefan

2003-08-01

To analyze the safety and effectiveness of a new monorail stent system for the treatment of failing femoropopliteal bypass grafts. Acute distal occlusions or stenoses of femoropopliteal bypass grafts were treated with balloon-expandable stents (13 or 18-mm diameter) pre-mounted on a monorail balloon catheter system. The delivery system was assessed subjectively for (1). compatibility with the sheath, (2). lesion crossing potential, (3). radiopacity, (4). flexibility of the catheter, (5). adequacy of stent expansion, and (5). balloon refolding. In 8 failing bypass grafts with distal lesions, the delivery system successfully deployed the stent at the desired location. Sheath compatibility, catheter flexibility, lesion crossing, and stent expansion were rated "excellent" by all examiners for the 18-mm device. Radiopacity of the mounted stent was graded "good" before and during positioning, but only "sufficient" following expansion. For this type of lesion, the investigators rated the overall performance of the device superior to conventional "over-the-wire" systems. The monorail balloon-expandable stent delivery system provides rapid introduction of the device over the guidewire, and its low profile facilitates the use of small sheaths to minimize access-site complications.

[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.

Measurement and Comparison of Mechanical Properties of Nitinol Stents

NASA Astrophysics Data System (ADS)

Hanus, Josef; Zahora, Jiri

2005-01-01

The self expandable Nitinol stents or stentgrafts are typically used for miniinvasive treatment of stenosis and aneurysms in the cardiovascular system. The minimal traumatisation of the patient, shorter time of hospitalization are typical advantages of these methods. More than ten years of experience has yielded also important information about the performance of stents in interaction with biological system and the possible problems related with it. The leakage or the shift of stent are some typical disadvantages, that can be related among other in the construction of the stent. The problem is that the mechanical properties, dimensions and the dynamical properties of the stent do not exactly correspond to the properties of the vessel or generally of tissue where this stent is introduced. The measurement, the description and the comparison of the relations between the mechanical properties of stents and tissues can be one of the possible ways to minimize these disadvantages. The developed original computer controlled measuring system allows the measurement of mechanical properties of stents, the measurement of strain-stress curves or simulation of interaction of the stent and vessel for exactly defined hemodynamic conditions. We measured and compared the mechanical parameters of different selfexpandable Nitinol stents, which differed in geometry (radius and length), in the type of construction (number of branches and rising of winding) and in the diameter of used wire. The results of measurements confirmed the theoretical assumptions that just the diameter of the Nitinol wire significantly influences the rigidity and the level of compressibility of the stent as well. A compromise must be found between the required rigidity of the stent and the minimal size of the delivery system. The exact description of the relation between the mechanical properties and geometry and construction of the stents enables to design the stent to fit the patient and it is expected that this access improves the efficiency of treatment. The results of measurement are also necessary for the design and identification of the parameters of the models of the stents.

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.

[Numerical simulation of the effect of virtual stent release pose on the expansion results].

PubMed

Li, Jing; Peng, Kun; Cui, Xinyang; Fu, Wenyu; Qiao, Aike

2018-04-01

The current finite element analysis of vascular stent expansion does not take into account the effect of the stent release pose on the expansion results. In this study, stent and vessel model were established by Pro/E. Five kinds of finite element assembly models were constructed by ABAQUS, including 0 degree without eccentricity model, 3 degree without eccentricity model, 5 degree without eccentricity model, 0 degree axial eccentricity model and 0 degree radial eccentricity model. These models were divided into two groups of experiments for numerical simulation with respect to angle and eccentricity. The mechanical parameters such as foreshortening rate, radial recoil rate and dog boning rate were calculated. The influence of angle and eccentricity on the numerical simulation was obtained by comparative analysis. Calculation results showed that the residual stenosis rates were 38.3%, 38.4%, 38.4%, 35.7% and 38.2% respectively for the 5 models. The results indicate that the pose has less effect on the numerical simulation results so that it can be neglected when the accuracy of the result is not highly required, and the basic model as 0 degree without eccentricity model is feasible for numerical simulation.

Development and evaluation of a centralised computerised registry for ureteric stents: completing the audit cycle.

PubMed

Davis, N F; Murray, G; O'Connor, T; Browne, C; MacCraith, E; Galvin, D; Mulvin, D; Quinlan, D; Lennon, G

2017-11-01

A forgotten ureteric stent may result in severe renal impairment leading to nephrectomy. To compare the effectiveness of a centralised computerised registry for monitoring ureteric stent activity with a previously established theatre stent logbook system. This prospective audit was performed in two 9-monthly intervals. During the first interval, insertion/removal of a ureteric stent was documented in a specific theatre stent logbook. In the second interval, an electronic centralised computerised registry was developed to document insertion/removal of a ureteric stent onto an accessible hospital server. A computerised traffic-light system was also developed to identify patients with an indwelling stent for >3 months. The primary outcome variable was the number of prolonged indwelling ureteric stents in both groups. During the first time interval, 188 ureteric stents were inserted and 182 (96%) were removed or changed. Six (4%) patients underwent insertion of a ureteric stent for a prolonged period of time (>6 months). This subgroup required complex endourological intervention for stent removal due to encrustation. During the second time interval, 157 ureteric stents were inserted and all patients had their stent removed or changed within 6 months. No patients in this group were lost to follow-up. This study demonstrates that a centralised computerised ureteric stent registry is superior to a conventional logbook for monitoring ureteric stent activity. We propose the introduction a centralised nationalised ureteric stent registry for eliminating the potential for prolonged or forgotten ureteric stents.

Treatment of benign and malignant tracheobronchial obstruction with metal wire stents: experience with a balloon-expandable and a self-expandable stent type.

PubMed

Rieger, Johannes; Hautmann, Hubert; Linsenmaier, Ulrich; Weber, Cristoph; Treitl, Markus; Huber, Rudolf Maria; Pfeifer, Klaus-Jürgen

2004-01-01

Over the last few years various types of metal wire stents have been increasingly employed in the treatment of both malignant and benign tracheobronchial obstruction. To date, however, few studies have investigated the in vivo properties of different stent types. We implanted 26 balloon-expandable tantalum Strecker stents (18 patients) and 18 self-expandable Wallstents (16 patients) into the tracheobronchial system of 30 patients with combined stenting in 4 patients. Mean age was 51 years (range: 0.5-79 years). Malignant disease was present in 23 patients, benign disease in seven patients. Both patients and individual stents were monitored clinically and radiographically. The probability of stents remaining within the tracheobronchial system, and of their remaining undislocated and uncompressed was calculated using Kaplan-Meier analysis for both stent types. Average stent follow-up time was 112 days until explantation and 115 days until patients' death or discharge. Kaplan-Meier analysis revealed a higher probability for the Wallstent to remain within the tracheobronchial system. Dislocation and compression occurred more rarely. Explantation, however, if desired, was more difficult compared to the Strecker stent. The Wallstent also led to the formation of granulation tissue, especially at the proximal stent end, frequently requiring reintervention. Both stent types proved to be effective therapeutic options in the management of obstructive tracheobronchial disease. The mechanical properties of the Strecker stent seem to be less favorable compared to the Wallstent but removal is easy. For benign disease, however, the Wallstent reveals limitations due to significant side effects.

Optimization of stent implantation using a high pressure inflation protocol.

PubMed

Vallurupalli, Srikanth; Bahia, Amit; Ruiz-Rodriguez, Ernesto; Ahmed, Zubair; Hakeem, Abdul; Uretsky, Barry F

2016-01-01

High-pressure inflation is the universal standard for stent deployment but a specific protocol for its use is lacking. We developed a standardized "pressure optimization protocol" (POP) using time to inflation pressure stability as an endpoint for determining the required duration of stent inflation. The primary study purpose was to determine the stent inflation time (IT) in a large patient cohort using the standardized inflation protocol, to correlate various patient and lesion characteristics with IT, and ascertain in an in vitro study the time for pressure accommodation within an inflation system. Six hundred fifteen stent implants in 435 patients were studied. Multivariate analysis was performed to determine predictors of longer ITs. In an in vitro study, various stents and balloons were inflated in air to determine the pressure accommodation time of the inflation system. The mean stent IT was 104 ± 41 sec (range 30-380 sec). Stent length was the only predictor of prolonged stent inflation. The "accommodation time" in vitro of the stent inflation system itself was 33 ± 24 sec. The protocol was safe requiring premature inflation termination in <3% of stent implants. No serious adverse events occurred. Achieving stable inflation pressure requires on average over 100 sec and may require several minutes in individual cases. Stent length increases IT. These results suggest that the widespread practice of rapid inflation/deflation may not be sufficient to fully expand the stent and that the use of a pressure stability protocol will allow for safe, predictable, and more complete stent deployment. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

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.

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.

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

PubMed

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

2015-09-01

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

76 FR 56200 - Circulatory System Devices Panel of the Medical Devices Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-12

... Stent. The ZILVER-PTX Stent is a self-expanding nitinol stent coated on its outer surface with the... millimeter. The ZILVER-PTX Stent is available in diameters ranging from 5 to 10 millimeters (mm) and lengths... deployment, the ZILVER-PTX Stent expands to establish and maintain patency in the stented region. The...

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.

Influence of different computational approaches for stent deployment on cerebral aneurysm haemodynamics

PubMed Central

Bernardini, Annarita; Larrabide, Ignacio; Morales, Hernán G.; Pennati, Giancarlo; Petrini, Lorenza; Cito, Salvatore; Frangi, Alejandro F.

2011-01-01

Cerebral aneurysms are abnormal focal dilatations of artery walls. The interest in virtual tools to help clinicians to value the effectiveness of different procedures for cerebral aneurysm treatment is constantly growing. This study is focused on the analysis of the influence of different stent deployment approaches on intra-aneurysmal haemodynamics using computational fluid dynamics (CFD). A self-expanding stent was deployed in an idealized aneurysmatic cerebral vessel in two initial positions. Different cases characterized by a progression of simplifications on stent modelling (geometry and material) and vessel material properties were set up, using finite element and fast virtual stenting methods. Then, CFD analysis was performed for untreated and stented vessels. Haemodynamic parameters were analysed qualitatively and quantitatively, comparing the cases and the two initial positions. All the cases predicted a reduction of average wall shear stress and average velocity of almost 50 per cent after stent deployment for both initial positions. Results highlighted that, although some differences in calculated parameters existed across the cases based on the modelling simplifications, all the approaches described the most important effects on intra-aneurysmal haemodynamics. Hence, simpler and faster modelling approaches could be included in clinical workflow and, despite the adopted simplifications, support clinicians in the treatment planning. PMID:22670204

Study of the Behavior of a Bell-Shaped Colonic Self-Expandable NiTi Stent under Peristaltic Movements

PubMed Central

Puértolas, José A.; López, Enrique

2013-01-01

Managing bowel obstruction produced by colon cancer requires an emergency intervention to patients usually in poor conditions, and it requires creating an intestinal stoma in most cases. Regardless of that the tumor may be resectable, a two-stage surgery is mandatory. To avoid these disadvantages, endoscopic placement of self-expanding stents has been introduced more than 10 years ago, as an alternative to relieve colonic obstruction. It can be used as a bridge to elective single-stage surgery avoiding a stoma or as a definitive palliative solution in patients with irresectable tumor or poor estimated survival. Stents must be capable of exerting an adequate radial pressure on the stenosed wall, keeping in mind that stent must not move or be crushed, guaranteeing an adequate lumen when affected by peristaltic waves. A finite element simulation of bell-shaped nitinol stent functionality has been done. Catheter introduction, releasing at position, and the effect of peristaltic wave were simulated. To check the reliability of the simulation, a clinical experimentation with porcine specimens was carried out. The stent presented a good deployment and flexibility. Stent behavior was excellent, expanding from the very narrow lumen corresponding to the maximum peristaltic pressure to the complete recovery of operative lumen when the pressure disappears. PMID:23841067

Expansion of the Multi-Link Frontier™ Coronary Bifurcation Stent: Micro-Computed Tomographic Assessment in Human Autopsy and Porcine Heart Samples

PubMed Central

Kralev, Stefan; Haag, Benjamin; Spannenberger, Jens; Lang, Siegfried; Brockmann, Marc A.; Bartling, Soenke; Marx, Alexander; Haase, Karl-Konstantin; Borggrefe, Martin; Süselbeck, Tim

2011-01-01

Background Treatment of coronary bifurcation lesions remains challenging, beyond the introduction of drug eluting stents. Dedicated stent systems are available to improve the technical approach to the treatment of these lesions. However dedicated stent systems have so far not reduced the incidence of stent restenosis. The aim of this study was to assess the expansion of the Multi-Link (ML) Frontier™ stent in human and porcine coronary arteries to provide the cardiologist with useful in-vitro information for stent implantation and selection. Methodology/Principal Findings Nine ML Frontier™ stents were implanted in seven human autopsy heart samples with known coronary artery disease and five ML Frontier™ stents were implanted in five porcine hearts. Proximal, distal and side branch diameters (PD, DD, SBD, respectively), corresponding opening areas (PA, DA, SBA) and the mean stent length (L) were assessed by micro-computed tomography (micro-CT). PD and PA were significantly smaller in human autopsy heart samples than in porcine heart samples (3.54±0.47 mm vs. 4.04±0.22 mm, p = 0.048; 10.00±2.42 mm2 vs. 12.84±1.38 mm2, p = 0.034, respectively) and than those given by the manufacturer (3.54±0.47 mm vs. 4.03 mm, p = 0.014). L was smaller in human autopsy heart samples than in porcine heart samples, although data did not reach significance (16.66±1.30 mm vs. 17.30±0.51 mm, p = 0.32), and significantly smaller than that given by the manufacturer (16.66±1.30 mm vs. 18 mm, p = 0.015). Conclusions/Significance Micro-CT is a feasible tool for exact surveying of dedicated stent systems and could make a contribution to the development of these devices. The proximal diameter and proximal area of the stent system were considerably smaller in human autopsy heart samples than in porcine heart samples and than those given by the manufacturer. Special consideration should be given to the stent deployment procedure (and to the follow-up) of dedicated stent systems, considering final intravascular ultrasound or optical coherence tomography to visualize (and if necessary optimize) stent expansion. PMID:21814552

Clinical Results and Problems of Percutaneous Transluminal Angioplasty and Stenting for Extracranial Internal Carotid Stenoses

PubMed Central

Tsuura, M.; Terada, T.; Masuo, O.; Matsumoto, H.; Itakura, T.; Hyoutani, G.; Nakamura, Y.; Moriwaki, H.; Hayashi, S.

2001-01-01

Summary 110 patients with extracranial ICA stenosis were treated by PTA or stenting. In 21 of 55 cases of only PTA and in 40 of 55 cases of stenting, we used our blocking balloon systems to prevent distal embolism. The morbidity and the mortality rates were 5.4% and 0%, respectively. There was only one embolic complication in cases of PTA or stenting where blocking balloon systems were used. In contrast, distal embolism occurred in 3 of 34 cases of PTA without blocking balloon systems (one symptomatic case) and in 4 of 15 cases of stenting without blocking balloon systems (3 symptomatic cases). Our blocking balloon catheter system is a useful device to reduce the risk of symptomatic distal embolism. PMID:20663375

Supera self-expanding stents for endovascular treatment of femoropopliteal disease: a review of the clinical evidence

PubMed Central

Bishu, Kalkidan; Armstrong, Ehrin J

2015-01-01

Femoropopliteal lesions account for a significant proportion of endovascular interventions for peripheral artery disease in patients with disabling claudication or chronic limb ischemia. The femoropopliteal artery crosses two joint structures (hip and knee joints) and courses through the muscular adductor canal in the thigh, which places the artery at increased biomechanical stress. There is a critical need for stent platforms with a reduced risk of stent fracture while maintaining patency during long-term follow-up. The Supera peripheral stent system has a braided nickel–titanium alloy stent designed to withstand the unique stressors along the course of the femoropopliteal artery. This design may be associated with improved patency in association with reduced stent fracture rates on short- and medium-term follow-up. Further studies, including randomized controlled studies, comparing the Supera interwoven nickel–titanium alloy stent system with other stent platforms and angioplasty alone are needed. PMID:26203255

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

77 FR 7589 - Neurological Devices Panel of the Medical Devices Advisory Committee; Notice of Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-13

... current knowledge about the safety and effectiveness of the Wingspan Stent System with Gateway PTA Balloon... premarket and postmarket data. The Wingspan Stent System with Gateway PTA Balloon Catheter is a neurovascular stent, balloon catheter, and delivery system consisting of the following components: 1. Wingspan...

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

Lee, Cheng-Hung; Department of Mechanical Engineering, Chang Gung University, Tao-Yuan, Taiwan; Jhong, Guan-Heng

The deployment of metallic stents during percutaneous coronary intervention has become common in the treatment of coronary bifurcation lesions. However, restenosis occurs mostly at the bifurcation area even in present era of drug-eluting stents. To achieve adequate deployment, physicians may unintentionally apply force to the strut of the stents through balloon, guiding catheters, or other devices. This force may deform the struts and impose excessive mechanical stresses on the arterial vessels, resulting in detrimental outcomes. This study investigated the relationship between the distribution of stress in a stent and bifurcation angle using finite element analysis. The unintentionally applied force followingmore » stent implantation was measured using a force sensor that was made in the laboratory. Geometrical information on the coronary arteries of 11 subjects was extracted from contrast-enhanced computed tomography scan data. The numerical results reveal that the application of force by physicians generated significantly higher mechanical stresses in the arterial bifurcation than in the proximal and distal parts of the stent (post hoc P < 0.01). The maximal stress on the vessels was significantly higher at bifurcation angle <70° than at angle ≧70° (P < 0.05). The maximal stress on the vessels was negatively correlated with bifurcation angle (P < 0.01). Stresses at the bifurcation ostium may cause arterial wall injury and restenosis, especially at small bifurcation angles. These finding highlight the effect of force-induced mechanical stress at coronary artery bifurcation stenting, and potential mechanisms of in-stent restenosis, along with their relationship with bifurcation angle.« less

A prospective, multicenter study of a double stent system for palliative treatment of malignant extrahepatic biliary obstructions.

PubMed

Kim, Jong Woo; Gwon, Dong Il; Han, Young-Min; Won, Je Hwan; Hong, Hyun Pyo; Ko, Gi-Young; Yoon, Hyun-Ki; Sung, Kyu-Bo

2015-10-01

A double stent system (covered stent in uncovered stent) was designed to provide long-term patency without tumor ingrowth or stent-related complications, such as stent migration, cholecystitis, or pancreatitis. To investigate the safety and efficacy of double stents in patients with malignant extrahepatic biliary obstructions. This prospective, nonrandomized, multicenter study enrolled 160 consecutive patients (102 men; mean age, 64 years; range, 33-91 years) with malignant extrahepatic biliary obstructions treated with a double stent system from January 2010 to March 2012. The technical success rate of the double stent placement was 100%. No stent migration was observed. Procedure-related minor (self-limiting hemobilia [n = 6] and cholangitis [n = 2]) and major (pancreatitis [n = 16], cholecystitis [n = 3], and hepatic abscess [n = 2]) complications occurred in a total of 29 patients. The mean serum bilirubin level, which was 8.9 ± 5.6 mg/dL before drainage, decreased to 2.2 ± 4.6 mg/dL 1 month after stent placement (P < 0.001). Successful internal drainage was achieved in 148 patients (92.5%). During the mean follow-up period of 205 days, acute cholecystitis (n = 3) and hepatic abscess (n = 2) occurred in five patients. The median patient survival and stent patency time were 135 days (95% confidence interval [CI], 96-160 days) and 114 days (95% CI, 83-131 days), respectively. Of 153 patients, 22 (14.4%) presented with stent dysfunction due to sludge incrustation (n = 17), tumor overgrowth (n = 4), or blood clot (n = 1), and required repeat intervention. Tumor ingrowth was not observed in any of these patients. Percutaneous treatment of malignant extrahepatic biliary obstruction using a double stent safely and effectively achieves internal biliary drainage. © The Foundation Acta Radiologica 2014.

76 FR 47210 - Medical Devices; Availability of Safety and Effectiveness Summaries for Premarket Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-04

.......... Medtronic Vascular.... Valiant thoracic stent graft April 1, 2011. system. H100002 FDA-2011-M-0241... Scientific Corp ION paclitaxel-eluting coronary April 22, 2011. stent system (monorail and over- the-wire..., 2011. toric IOL. P040012 (S34) FDA-2011-M-0343. Abbott Vascular, Inc.. RX Acculink carotid stent system...

76 FR 31965 - Medical Devices; Availability of Safety and Effectiveness Summaries for Premarket Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-02

.... ENDURANT STENT GRAFT SYSTEM. FDA-2011-M-0040 P100010 Medtronic Cryocath, ARCTIC FRONT December 17, 2010. LP.... Vascular. LX VASCULAR STENT SYSTEMS. FDA-2011-M-0039 P070026 Depuy, Inc......... CERAMAX CERAMIC HIP.... EXPANDABLE RENAL STENT SYSTEM. FDA-2011-M-0056 P090013 Medtronic, Inc..... REVO MRI SURESCAN IPG February 8...

77 FR 15779 - Medical Devices; Availability of Safety and Effectiveness Summaries for Premarket Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-16

... 26, 2011. iliac balloon- expandable stent system. P100042, FDA-2011-M-0792 Gen-Probe APTIMA HPV assay..., 2011. XIENCE PRIME LL EVEROLIMUS-eluting coronary stent system. P100041, FDA-2011-M-0837 Edwards.... EVEROLIMUS-eluting platinum chromium coronary stent system. P100024, FDA-2011-M-0866 Dako Denmark A/S...

Comparison of partially covered nitinol stents with partially covered stainless stents as a historical control in a multicenter study of distal malignant biliary obstruction: the WATCH study.

PubMed

Isayama, Hiroyuki; Mukai, Tsuyoshi; Itoi, Takao; Maetani, Iruru; Nakai, Yousuke; Kawakami, Hiroshi; Yasuda, Ichiro; Maguchi, Hiroyuki; Ryozawa, Shomei; Hanada, Keiji; Hasebe, Osamu; Ito, Kei; Kawamoto, Hirofumi; Mochizuki, Hitoshi; Igarashi, Yoshinori; Irisawa, Atsushi; Sasaki, Tamito; Togawa, Osamu; Hara, Taro; Kamada, Hideki; Toda, Nobuo; Kogure, Hirofumi

2012-07-01

Covered self-expandable metal stents (CSEMSs) were developed to prevent tumor ingrowth, but stent migration is one of the problems with CSEMSs. To evaluate a new, commercially available CSEMS with flared ends and low axial force compared with a commercially available CSEMS without the anti-migration system and high axial force. Multicenter, prospective study with a historical cohort. Twenty Japanese referral centers. This study involved patients with unresectable distal malignant biliary obstruction. Placement of a new, commercially available, partially covered SEMS. Recurrent biliary obstruction rate, time to recurrent biliary obstruction, stent-related complications, survival. Between April 2009 and March 2010, 141 patients underwent partially covered nitinol stent placement, and between May 2001 and January 2007, 138 patients underwent placement of partially covered stainless stents as a historical control. The silicone cover of the partially covered nitinol stents prevented tumor ingrowth. There were no significant differences in survival (229 vs 219 days; P = .250) or the rate of recurrent biliary obstruction (33% vs 38%; P = .385) between partially covered nitinol stents and partially covered stainless stents. Stent migration was less frequent (8% vs 17%; P = .019), and time to recurrent biliary obstruction was significantly longer (373 vs 285 days; P = .007) with partially covered nitinol stents. Stent removal was successful in 26 of 27 patients (96%). Nonrandomized, controlled trial. Partially covered nitinol stents with an anti-migration system and less axial force demonstrated longer time to recurrent biliary obstruction with no tumor ingrowth and less stent migration. Copyright © 2012 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

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.

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.

Frequency of Angina Pectoris After Percutaneous Coronary Intervention and the Effect of Metallic Stent Type.

PubMed

Gaglia, Michael A; Torguson, Rebecca; Lipinski, Michael J; Gai, Jiaxiang; Koifman, Edward; Kiramijyan, Sarkis; Negi, Smita; Rogers, Toby; Steinvil, Arie; Suddath, William O; Satler, Lowell F; Pichard, Augusto D; Waksman, Ron

2016-02-15

Although metallic coronary stents significantly reduce angina pectoris compared with optimal medical therapy, angina after percutaneous coronary intervention (PCI) remains frequent. We, therefore, sought to compare the incidence of any angina during the 1 year after PCI among the spectrum of commercially available metallic stents. Metallic stent type was classified as bare metal stent, Cypher, Taxus Express, Xience V, Promus Element, and Resolute. The primary end point was patient-reported angina within 1 year of PCI. Multivariable logistic regression was performed to assess the independent association of stent type with any angina at 1 year. Overall, 8,804 patients were queried in regard to angina symptoms; 32.3% experienced angina at some point in the first year after PCI. Major adverse cardiovascular events, a composite of all-cause mortality, target vessel revascularization, and Q-wave myocardial infarction, increased with angina severity: 6.8% for patients without angina, 10.0% for patients with class 1 or 2 angina, and 19.7% for patients with class 3 or 4 angina (p <0.001 for trend). After multivariable adjustment, there was no significant association between stent type and angina at 1 year after PCI. Baseline Canadian Cardiovascular Society class 3 or 4 angina, history of coronary artery bypass grafting, and history of PCI were associated with a higher likelihood of angina at 1 year; increasing age, male gender, presentation with acute coronary syndrome, and higher stented length were associated with less angina. In conclusion, metallic stent type is not associated with the occurrence of angina at up to 1 year after PCI. Copyright © 2016 Elsevier Inc. All rights reserved.

Fatigue Assessment of Nickel-Titanium Peripheral Stents: Comparison of Multi-Axial Fatigue Models

NASA Astrophysics Data System (ADS)

Allegretti, Dario; Berti, Francesca; Migliavacca, Francesco; Pennati, Giancarlo; Petrini, Lorenza

2018-03-01

Peripheral Nickel-Titanium (NiTi) stents exploit super-elasticity to treat femoropopliteal artery atherosclerosis. The stent is subject to cyclic loads, which may lead to fatigue fracture and treatment failure. The complexity of the loading conditions and device geometry, coupled with the nonlinear material behavior, may induce multi-axial and non-proportional deformation. Finite element analysis can assess the fatigue risk, by comparing the device state of stress with the material fatigue limit. The most suitable fatigue model is not fully understood for NiTi devices, due to its complex thermo-mechanical behavior. This paper assesses the fatigue behavior of NiTi stents through computational models and experimental validation. Four different strain-based models are considered: the von Mises criterion and three critical plane models (Fatemi-Socie, Brown-Miller, and Smith-Watson-Topper models). Two stents, made of the same material with different cell geometries are manufactured, and their fatigue behavior is experimentally characterized. The comparison between experimental and numerical results highlights an overestimation of the failure risk by the von Mises criterion. On the contrary, the selected critical plane models, even if based on different damage mechanisms, give a better fatigue life estimation. Further investigations on crack propagation mechanisms of NiTi stents are required to properly select the most reliable fatigue model.

Fatigue Assessment of Nickel-Titanium Peripheral Stents: Comparison of Multi-Axial Fatigue Models

NASA Astrophysics Data System (ADS)

Allegretti, Dario; Berti, Francesca; Migliavacca, Francesco; Pennati, Giancarlo; Petrini, Lorenza

2018-02-01

Peripheral Nickel-Titanium (NiTi) stents exploit super-elasticity to treat femoropopliteal artery atherosclerosis. The stent is subject to cyclic loads, which may lead to fatigue fracture and treatment failure. The complexity of the loading conditions and device geometry, coupled with the nonlinear material behavior, may induce multi-axial and non-proportional deformation. Finite element analysis can assess the fatigue risk, by comparing the device state of stress with the material fatigue limit. The most suitable fatigue model is not fully understood for NiTi devices, due to its complex thermo-mechanical behavior. This paper assesses the fatigue behavior of NiTi stents through computational models and experimental validation. Four different strain-based models are considered: the von Mises criterion and three critical plane models (Fatemi-Socie, Brown-Miller, and Smith-Watson-Topper models). Two stents, made of the same material with different cell geometries are manufactured, and their fatigue behavior is experimentally characterized. The comparison between experimental and numerical results highlights an overestimation of the failure risk by the von Mises criterion. On the contrary, the selected critical plane models, even if based on different damage mechanisms, give a better fatigue life estimation. Further investigations on crack propagation mechanisms of NiTi stents are required to properly select the most reliable fatigue model.

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.

Microbiology and Biofilm Trends of Silicone Lacrimal Implants: Comparing Infected Versus Routinely Removed Stents.

PubMed

Samimi, David B; Ediriwickrema, Lilangi S; Bielory, Brett P; Miller, Darlene; Lee, Wendy; Johnson, Thomas E

To investigate the pathogens and biofilms responsible for clinically significant infection of silicone stents implanted within the lacrimal system. Retrospective review of culture results and patient demographics for all silicone lacrimal stents removed early for clinically significant infection and sent to the Bascom Palmer Microbiology Laboratory through the end of year 2010. As a control, routinely removed, clinically noninfected stents from the same institution were prospectively sent for culture over a 6-month period. Four clinically infected and 6 clinically noninfected stents showing mucus within the lumen at removal were sent for scanning electron microscopy. Images were randomized and graded by a microbiologist for the presence of organisms, matrix deposits, organisms within matrix, and overall impression of significant biofilm formation. Nineteen stents were included in the study; 100% of clinically infected (n = 10) and noninfected (n = 9) stents were culture positive. Culture positivity for nontuberculous mycobacterium was found in 90% of infected stents and none of the noninfected stents (p < 0.001). Of infected stents, 50% grew Gram-positive organisms compared with 89% of noninfected stents (p = 0.07). Fifty percent of infected versus 67% of noninfected stents were culture positive for Gram-negative organisms (p = 0.46). Electron microscopy of stents revealed organisms consistent with culture results (size, shape) in planktonic and biofilm form. Masked observer image grading revealed a statistically significant higher amount of organism and biofilm on infected versus noninfected specimen. Nontuberculous mycobacteria comprise the primary pathogens responsible for clinically significant infection of silicone stents in the lacrimal system in South Florida. Robust biofilm production by this organism likely plays a role in pathogenesis. Further research into biofilm-related lacrimal implant infection may aid in the development of useful prevention and treatment strategies.

Biomechanical Impact of Wrong Positioning of a Dedicated Stent for Coronary Bifurcations: A Virtual Bench Testing Study.

PubMed

Chiastra, Claudio; Grundeken, Maik J; Collet, Carlos; Wu, Wei; Wykrzykowska, Joanna J; Pennati, Giancarlo; Dubini, Gabriele; Migliavacca, Francesco

2018-05-17

The treatment of coronary bifurcations is challenging for interventional cardiologists. The Tryton stent (Tryton Medical, Inc., USA) is one of the few devices specifically designed for coronary bifurcations that underwent large clinical trials. Although the manufacturer provides specific recommendations to position the stent in the bifurcation side branch (SB) according to four radio-opaque markers under angiographic guidance, wrong device positioning may accidentally occur. In this study, the virtual bench testing approach was used to investigate the impact of wrong positioning of the Tryton stent in coronary bifurcations in terms of geometrical and biomechanical criteria. A finite element model of the left anterior descending/first diagonal coronary bifurcation was created with a 45° distal angle and realistic lumen diameters. A validated model of the Tryton stent mounted on stepped delivery balloon was used. All steps of the Tryton deployment sequence were simulated. Three Tryton positions, namely 'proximal', 'recommended', and 'distal' positions, obtained by progressively implanting the stent more distally in the SB, were compared. The 'recommended' case exhibited the lowest ostial area stenosis (44.8 vs. 74.3% ('proximal') and 51.5% ('distal')), the highest diameter at the SB ostium (2.81 vs. 2.70 mm ('proximal') and 2.54 mm ('distal')), low stent malapposition (9.9 vs. 16.3% ('proximal') and 8.5% ('distal')), and the lowest peak wall stress (0.37 vs. 2.20 MPa ('proximal') and 0.71 MPa ('distal')). In conclusion, the study shows that a 'recommended' Tryton stent positioning may be required for optimal clinical results.

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 Side Branch Access DES is a viable device for consistently accessing coronary bifurcation lesions; it allows for easy wire access into the side branch. This may assist the operator in overcoming those well-recognized limitations associated with use of standard one- or two-stent strategies. In this perfused synthetic coronary model, Xience SBA deployment required less contrast usage and shorter fluoroscopy times. Further testing of this device is warranted.

Preliminary study for a newly designed silicone stent and delivery system for canine obstructive tracheal disease.

PubMed

Kim, Dae-Hyun; Choi, Chi-Bong; Chung, Wook-Hun; Lee, Sung-Ho; Lee, A-Jin; Jeong, Jae-Seung; Kim, Ho-Joong; Kim, Hwi-Yool

2012-10-01

The goal of this study was to prove the possibility of using silicone stents broadly used for human medicine in canine obstructive tracheal disease. A silicone stent anatomically designed for canine trachea was tested on 5 beagle dogs for 8 weeks. The stent was carefully inserted using a newly developed delivery device under fluoroscopic guidance. There were no technical difficulties in placing the stent during the procedure. Previously reported complications of airway stenting such as stent migration or granulation tissue formation did not occur in any of the cases. In addition, removal of the stent was as simple as inserting it, and complications were absent. The stent introduced in this study could possibly be applied to various canine obstructive tracheal diseases.

A recoil resilient lumen support, design, fabrication and mechanical evaluation

NASA Astrophysics Data System (ADS)

Mehdizadeh, Arash; Ali, Mohamed Sultan Mohamed; Takahata, Kenichi; Al-Sarawi, Said; Abbott, Derek

2013-06-01

Stents are artificial implants that provide scaffolding to a cavity inside the body. This paper presents a new luminal device for reducing the mechanical failure of stents due to recoil, which is one of the most important issues in stenting. This device, which we call a recoil-resilient ring (RRR), is utilized standalone or potentially integrated with existing stents to address the problem of recoil. The proposed structure aims to minimize the need for high-pressure overexpansion that can induce intra-luminal trauma and excess growth of vascular tissue causing later restenosis. The RRR is an overlapped open ring with asymmetrical sawtooth structures that are intermeshed. These teeth can slide on top of each other, while the ring is radially expanded, but interlock step-by-step so as to keep the final expanded state against compressional forces that normally cause recoil. The RRRs thus deliver balloon expandability and, when integrated with a stent, bring both radial rigidity and longitudinal flexibility to the stent. The design of the RRR is investigated through finite element analysis (FEA), and then the devices are fabricated using micro-electro-discharge machining of 200-µm-thick Nitinol sheet. The standalone RRR is balloon expandable in vitro by 5-7 Atm in pressure, which is well within the recommended in vivo pressure ranges for stenting procedures. FEA compression tests indicate 13× less reduction of the cross-sectional area of the RRR compared with a typical stainless steel stent. These results also show perfect elastic recovery of the RRR after removal of the pressure compared to the remaining plastic deformations of the stainless steel stent. On the other hand, experimental loading tests show that the fabricated RRRs have 2.8× radial stiffness compared to a two-column section of a commercial stent while exhibiting comparable elastic recovery. Furthermore, testing of in vitro expansion in a mock artery tube shows around 2.9% recoil, approximately 5-11× smaller than the recoil reported for commercial stents. These experimental results demonstrate the effectiveness of the device design for the targeted luminal support and stenting applications.

A clinical evaluation of the ProNOVA XR polymer-free sirolimus eluting coronary stent system in the treatment of patients with de novo coronary artery lesions (EURONOVA XR I study)☆

PubMed Central

Legutko, Jacek; Zasada, Wojciech; Kałuża, Grzegorz L.; Heba, Grzegorz; Rzeszutko, Lukasz; Jakala, Jacek; Dragan, Jacek; Klecha, Artur; Giszterowicz, Dawid; Dobrowolski, Wojciech; Partyka, Łukasz; Jayaraman, Swaminathan; Dudek, Dariusz

2013-01-01

Aims Evaluation of safety and efficacy of ProNOVA XR, a new generation of polymer-free sirolimus eluting stents (SES), utilizing a pharmaceutical excipient for timed release of sirolimus from the XR platform. Methods and results Safety and efficacy of ProNOVA XR coronary stent system was examined in EURONOVA prospective, single arm, multi-center registry of 50 patients with de novo native coronary lesions up to 28 mm in length in arteries between 2.25 and 4 mm. At 6-month, in-stent late lumen loss by QCA was 0.45 ± 0.41 mm and in-stent neointimal volume obstruction in the IVUS sub-study was 14 ± 11%. One-year clinical follow-up revealed a favorable safety profile, with 2% of in-hospital MACE and 6.4% of MACE from hospital discharge up to 12 months (including 1 cardiac death >30 days after stent implantation and 2 TLRs). According to the ARC definition, there was no definite or probable stent thrombosis and 1 possible stent thrombosis (2%) up to 12 months of clinical follow-up. Conclusions In this preliminary evaluation, ProNOVA XR polymer-free sirolimus eluting stent system appeared safe with an early promise of adequate effectiveness in the treatment of de novo coronary lesions in up to 12 months of clinical, angiographic and IVUS follow-up. PMID:23992999

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.

Differentiated analysis of an everolimus-eluting stent and a paclitaxel-eluting stent among higher risk subgroups for restenosis: results from the SPIRIT II trial.

PubMed

Khattab, Ahmed A; Richardt, Gert; Verin, Vitali; Kelbaek, Henning; Macaya, Carlos; Berland, Jacques; Miquel-Hebert, Karine; Dorange, Cécile; Serruys, Patrick W

2008-03-01

Restenosis is higher among certain subpopulations when subjected to percutaneous coronary interventions even when using drug-eluting stents. The randomised SPIRIT II trial demonstrated the superiority of the XIENCE V Everolimus Eluting Coronary Stent System over the TAXUS Paclitaxel-Eluting Stent System in terms of in-stent late loss at six months among 300 patients treated for de novo native coronary artery lesions. In this post-hoc analysis of SPIRIT II we focused on six-month angiographic outcomes of diabetic patients (n=69), left anterior descending arteries (n=149), long lesions >20 mm (n=43), small vessels <3.0 mm (n=209) and type B2 and C lesions (n=233). In-stent late loss was consistently less among all subgroups when treated by everolimus-eluting stents compared to paclitaxel-eluting stents: diabetics 0.15+/-0.26 mm versus 0.39+/-0.34 mm, p=0.006; LAD 0.12+/-0.23 mm versus 0.44+/-0.37 mm, p<0.001; long lesions 0.13+/-0.26 mm versus 0.43+/-0.46 mm, p=0.070; small vessels 0.17+/-0.28 mm versus 0.37+/-0.39 mm, p<0.001; B2/C lesions 0.12+/-0.31 mm versus 0.36+/-0.36 mm, p<0.001. The everolimus-eluting stent remained superior in terms of in-stent late loss in a variety of higher risk populations for restenosis compared to the paclitaxel-eluting stent. These analyses were consistent with the in-stent late loss results of the overall SPIRIT II trial population.

Automated stent defect detection and classification with a high numerical aperture optical system

NASA Astrophysics Data System (ADS)

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

2017-06-01

Stent quality control is a highly critical process. Cardiovascular stents have to be inspected 100% so as no defective stent is implanted in a human body. However, this visual control is currently performed manually and every stent could need tenths of minutes to be inspected. In this paper, a novel optical inspection system is presented. By the combination of a high numerical aperture (NA) optical system, a rotational stage and a line-scan camera, unrolled sections of the outer and inner surfaces of the stent are obtained and image-processed at high speed. Defects appearing in those surfaces and also in the edges are extremely contrasted due to the shadowing effect of the high NA illumination and acquisition approach. Therefore by means of morphological operations and a sensitivity parameter, defects are detected. Based on a trained defect library, a binary classifier sorts each kind of defect through a set of scoring vectors, providing the quality operator with all the required information to finally take a decision. We expect this new approach to make defect detection completely objective and to dramatically reduce the time and cost of stent quality control stage.

Causes of failure with Szabo technique - an analysis of nine cases.

PubMed

Jain, Rajendra Kumar; Padmanabhan, T N C; Chitnis, Nishad

2013-01-01

The objective of this case series is to identify and define causes of failure of Szabo technique in rapid-exchange monorail system for ostial lesions. From March 2009 to March 2011, 42 patients with an ostial lesion were treated percutaneously at our institution using Szabo technique in a monorail stent system. All patients received unfractionated heparin during intervention. Loading dose of clopidogrel, followed by clopidogrel and aspirin was administered. In 57% of patients, drug-eluting stents were used and in 42.8% patients bare metal stents. The stent was advanced over both wires, the target wire and the anchor wire. The anchor wire, which was passed through the proximal trailing strut of the stent helps to achieve precise stenting. The procedure was considered to be successful if stent was placed precisely covering the lesion and without stent loss or anchor wire prolapsing. Of the total 42 patients, the procedure was successful in 33, while failed in 9. Majority of failures were due to wire entanglement, which was fixed successfully in 3 cases by removing and reinserting the anchor wire. Out of other three failures, in one stent dislodgment occurred, stent could not cross the lesion in one and in another anchor wire got looped and prolapsed into target vessel. This case series shows that the Szabo technique, in spite of some difficulties like wire entanglement, stent dislodgement and resistance during stent advancement, is a simple and feasible method for treating variety of ostial lesions precisely compared to conventional angioplasty. Copyright © 2013 Cardiological Society of India. Published by Elsevier B.V. All rights reserved.

Causes of failure with Szabo technique – An analysis of nine cases

PubMed Central

Jain, Rajendra Kumar; Padmanabhan, T.N.C.; Chitnis, Nishad

2013-01-01

Objective The objective of this case series is to identify and define causes of failure of Szabo technique in rapid-exchange monorail system for ostial lesions. Methods and results From March 2009 to March 2011, 42 patients with an ostial lesion were treated percutaneously at our institution using Szabo technique in a monorail stent system. All patients received unfractionated heparin during intervention. Loading dose of clopidogrel, followed by clopidogrel and aspirin was administered. In 57% of patients, drug-eluting stents were used and in 42.8% patients bare metal stents. The stent was advanced over both wires, the target wire and the anchor wire. The anchor wire, which was passed through the proximal trailing strut of the stent helps to achieve precise stenting. The procedure was considered to be successful if stent was placed precisely covering the lesion and without stent loss or anchor wire prolapsing. Of the total 42 patients, the procedure was successful in 33, while failed in 9. Majority of failures were due to wire entanglement, which was fixed successfully in 3 cases by removing and reinserting the anchor wire. Out of other three failures, in one stent dislodgment occurred, stent could not cross the lesion in one and in another anchor wire got looped and prolapsed into target vessel. Conclusion This case series shows that the Szabo technique, in spite of some difficulties like wire entanglement, stent dislodgement and resistance during stent advancement, is a simple and feasible method for treating variety of ostial lesions precisely compared to conventional angioplasty. PMID:23809379

77 FR 60704 - Medical Devices; Availability of Safety and Effectiveness Summaries for Premarket Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-10-04

...] Fenestrated April 4, 2012. AAA Endovascular Graft (with the adjunctive Zenith Alignment Stent). P110029, FDA...\\ plus CoCr April 12, 2012. Coronary Stent on RX System. P110035, FDA-2012-M-0373 Boston Scientific Epic\\TM\\ Vascular Self- April 13, 2012. Corp. Expanding Stent System. P090015, FDA-2012-M-0390 Leica...

Comparison of everolimus- and paclitaxel-eluting stents in patients with acute and stable coronary syndromes: pooled results from the SPIRIT (A Clinical Evaluation of the XIENCE V Everolimus Eluting Coronary Stent System) and COMPARE (A Trial of Everolimus-Eluting Stents and Paclitaxel-Eluting Stents for Coronary Revascularization in Daily Practice) Trials.

PubMed

Planer, David; Smits, Pieter C; Kereiakes, Dean J; Kedhi, Elvin; Fahy, Martin; Xu, Ke; Serruys, Patrick W; Stone, Gregg W

2011-10-01

This study sought to compare the clinical outcomes of everolimus-eluting stents (EES) versus paclitaxel-eluting stents (PES) in patients with acute coronary syndromes (ACS) and stable coronary artery disease (CAD). Although randomized trials have shown superiority of EES to PES, the safety and efficacy of EES in ACS is unknown. We performed a patient-level pooled analysis from the prospective, randomized SPIRIT (Clinical Evaluation of the XIENCE V Everolimus Eluting Coronary Stent System) II, III, IV, and COMPARE (A Trial of Everolimus-Eluting Stents and Paclitaxel-Eluting Stents for Coronary Revascularization in Daily Practice) trials in which 2,381 patients with ACS and 4,404 patients with stable CAD were randomized to EES or to PES. Kaplan-Meier estimates of death, myocardial infarction (MI), ischemia-driven target lesion revascularization, and stent thrombosis were assessed at 2 years and stratified by clinical presentation (ACS vs. stable CAD). At 2 years, patients with ACS compared with stable CAD had higher rates of death (3.2% vs. 2.4%, hazard ratio [HR]: 1.37 [95% confidence interval (CI): 1.02 to 1.85], p = 0.04) and MI (4.9% vs. 3.4%, HR: 1.45 [95% CI: 1.14 to 1.85], p = 0.02). In patients with ACS, EES versus PES reduced the rate of death or MI (6.6% vs. 9.3%, HR: 0.70 [95% CI: 0.52 to 0.94], p = 0.02), stent thrombosis (0.7% vs. 2.9%, HR: 0.25 [95% CI: 0.12 to 0.52], p = 0.0002), and ischemia-driven target lesion revascularization (4.7% vs. 6.2%, HR: 0.69 [95% CI: 0.48 to 0.99], p = 0.04). In patients with stable CAD, EES reduced the rate of death or MI (4.5% vs. 7.1%, HR: 0.62 [95% CI: 0.48 to 0.80], p = 0.0002), stent thrombosis (0.7% vs. 1.8%, HR: 0.34 [95% CI: 0.19 to 0.62], p = 0.0002), and ischemia-driven target lesion revascularization (3.9% vs. 6.9%, HR: 0.55 [95% CI: 0.42 to 0.73], p < 0.0001). Treatment with EES versus PES provides enhanced safety and efficacy regardless of the acuity of the clinical syndrome being treated and appears to mitigate the increased risk of stent thrombosis associated with ACS. (A Clinical Evaluation of the XIENCE V Everolimus Eluting Coronary Stent System in the Treatment of Patients With de Novo Native Coronary Artery Lesions [SPIRIT II]; NCT00180310; SPIRIT III: A Clinical Evaluation of the Investigational Device XIENCE V Everolimus Eluting Coronary Stent System [EECSS] in the Treatment of Subjects With de Novo Native Coronary Artery Lesions [SPIRIT III]; NCT00180479; SPIRIT IV Clinical Trial: Clinical Evaluation of the XIENCE V Everolimus Eluting Coronary Stent System in the Treatment of Subjects With de Novo Native Coronary Artery Lesions [SPIRIT IV]; NCT00307047; A Trial of Everolimus-Eluting Stents and Paclitaxel-Eluting Stents for Coronary Revascularization in Daily Practice: the COMPARE Trial [COMPARE]; NCT01016041). Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. 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.

Fiber-reinforced silicone for tracheobronchial stents: An experimental study.

PubMed

Vearick, Samanta Bianchi; Demétrio, Kétner Bendo; Xavier, Rogério Gastal; Moreschi, Alexandre Heitor; Muller, André Frotta; Sanches, Paulo Roberto Stefani; Dos Santos, Luis Alberto Loureiro

2018-01-01

A trachea is a tubular structure composed of smooth muscle that is reinforced with cartilage rings. Some diseases can cause sagging in smooth muscle and cartilaginous tissue. The end result is reduction (narrowing) of the trachea diameter. A solution to this problem is the use of tracheal stents, which are small tubular devices made of silicone. One is inserted into the trachea to prevent or correct its constriction. The purpose of tracheal stent use is to maintain cartilage support that would otherwise be lost in the airway. Current tracheal stent models present limitations in terms of shape and characteristics of the silicone used in their production. One of the most important is the large thickness of the wall, which makes its placement difficult; this mainly applies to pediatric patients. The wall thickness of the stent is closely related to the mechanical properties of the material. This study aims to test the reinforcement of silicone with three kinds of fibers, and then stents that were produced using fiber with the best compressive strength characteristics. Silicone samples were reinforced with polypropylene (PP), polyamide (PA), and carbon fiber (CF) at concentrations of 2% and 4% (vol%), which then underwent tensile strength and Shore A hardness testing. Samples with fiber showed good characteristics; surface analyses were carried out and they were used to produce stents with an internal diameter of 11 or 13mm and a length of 50mm. Stents underwent compression tests for qualitative evaluation. Samples with 2% and 4% CF blends showed the best mechanical performance, and they were used to produce stents. These samples presented similar compressive strengths at low deformation, but stents with a 4% CF blend exhibited improved compressive strength at deformations greater than 30-50% of their diameter (P ≤ 0.05). The addition of 2% and 4% CF blends conferred greater mechanical strength and resistance to the silicone matrix. This is particularly true at low deformation, which is the condition where the stent is used when implanted. In the finite element compression strength tests, the stent composite showed greater compression strength with the addition of fiber, and the results were in accordance with mechanical compression tests performed on the stents. In vivo tests showed that, after 30 days of post-implantation in sheep trachea, an inflammatory process occurred in the region of the trachea in contact with the stent composite and with the stent without fiber (WF). This response is a common process during the first few days of implantation. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

2015-08-01

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

Stent-based delivery of adeno-associated viral vectors with sustained vascular transduction and iNOS-mediated inhibition of in-stent restenosis

PubMed Central

Fishbein, Ilia; Guerrero, David T.; Alferiev, Ivan S.; Foster, Jonathan B.; Minutolo, Nicholas G.; Chorny, Michael; Mas Monteys, Alejandro; Driesbaugh, Kathryn H.; Nagaswami, Chandrasekaran; Levy, Robert J.

2017-01-01

In-stent restenosis remains an important clinical problem in the era of drug eluting stents. Development of clinical gene therapy protocols for the prevention and treatment of in-stent restenosis is hampered by the lack of adequate local delivery systems. Herein we describe a novel stent-based gene delivery platform capable of providing local arterial gene transfer with adeno-associated viral (AAV) vectors. This system exploits the natural affinity of protein G (PrG) to bind to the Fc region of mammalian IgG, making PrG a universal adaptor for surface immobilization of vector-capturing antibodies (Ab). Our results: 1) demonstrate the feasibility of reversible immobilization of AAV2 vectors using vector tethering by AAV2-specific Ab appended to the stent surface through covalently attached PrG, 2) show sustained release kinetics of PrG/Ab-immobilized AAV2 vector particles into simulated physiological medium in vitro and site-specific transduction of cultured cells, 3) provide evidence of long-term (12 weeks) arterial expression of luciferase with PrG/Ab-tethered AAV2Luc, and 4) show anti-proliferative activity and anti-restenotic efficacy of stent-immobilized AAV2iNOS in the rat carotid artery model of stent angioplasty. PMID:28832561

Robot-assisted antegrade in-situ fenestrated stent grafting.

PubMed

Riga, Celia V; Bicknell, Colin D; Wallace, Daniel; Hamady, Mohamad; Cheshire, Nicholas

2009-05-01

To determine the technical feasibility of a novel approach of in-situ fenestration of aortic stent grafts by using a remotely controlled robotic steerable catheter system in the porcine model. A 65-kg pig underwent robot-assisted bilateral antegrade in-situ renal fenestration of an abdominal aortic stent graft with subsequent successful deployment of a bare metal stent into the right renal artery. A 16-mm iliac extension covered stent served as the porcine aortic endograft. Under fluoroscopic guidance, the graft was punctured with a 20-G customized diathermy needle that was introduced and kept in place by the robotic arm. The needle was exchanged for a 4 x 20 mm cutting balloon before successful deployment of the renal stent. Robot-assisted antegrade in-situ fenestration is technically feasible in a large mammalian model. The robotic system enables precise manipulation, stable positioning, and minimum instrumentation of the aorta and its branches while minimizing radiation exposure.

Robot-assisted laparoscopic pyeloureterostomy in infants with duplex systems and upper pole hydronephrosis: Variations in double-J ureteral stenting techniques.

PubMed

Baek, Minki; Au, Jason; Huang, Gene O; Koh, Chester J

2017-04-01

We describe our experience with robot-assisted laparoscopic (RAL) pyeloureterostomy in infants with duplex systems and upper pole hydronephrosis with an emphasis on the various double J (DJ) ureteral stent placement techniques. We used our RAL pyeloureterostomy technique in two female infants with duplex systems and upper pole hydronephrosis. For case 1, we introduced the DJ stent and placed it in the recipient lower pole ureter during the robotic operation in an antegrade fashion. For case 2, we inserted the DJ stent during retrograde pyelography prior to the robotic procedure in a retrograde fashion, and the proximal portion of the stent was placed across the anastomosis into the upper pole renal pelvis. Postoperatively, each of the patients were discharged on postoperative day 1 without complications. The postoperative renal ultrasound at 3 months demonstrated marked improvement of the right upper pole hydronephrosis in both patients. RAL pyeloureterostomy represents a minimally invasive option for upper tract reconstruction of duplex systems with upper pole hydronephrosis in infants. The DJ stent can be placed at the beginning or during the procedure. The stent can be placed in the lower pole ureter or across the anastomosis into the upper pole renal pelvis. Copyright © 2017 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

TOKYO criteria 2014 for transpapillary biliary stenting.

PubMed

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

2015-01-01

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

Evaluation of Polyurethane Nasolacrimal Duct Stents: In Vivo Studies in New Zealand Rabbits

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

Wilhelm, K.E., E-mail: wilhelm@uni-bonn.de; Grabolle, B.; Urbach, H.

2006-10-15

The purpose of this study was to evaluate the radiographic and biological effects of different polyurethane nasolacrimal duct stents in an animal model. Fifteen polyurethane nasolacrimal duct stents (n = 5 mushroom-type stents, n = 5 newly designed S-shaped TearLeader stents without hydrophilic coating, and n = 5 S-shaped TearLeader stents with hydrophilic coating) were implanted in the nasolacrimal ducts of eight unaffected New Zealand rabbits. One nasolacrimal system served as control. Clinical and radiographic follow-up was performed at 1-, 2-, and 4-week intervals, then after a 3-month interval, after which the animals were euthanized. All stents were implanted withoutmore » major periprocedural complications. The stents proved to be patent by the end of the procedure. During follow-up, all mushroom-type stents were occluded at 4 weeks. None of these stents opened to forced irrigation. Clinically, all rabbits demonstrated severe dacryocystitis. Three out of five TearLeader stents without hydrophilic coating were blocked at 4 weeks; one out of five was open to irrigation. Best results were observed in the stent group with hydrophilic coating. Follow-up dacryocystography demonstrated patent stents in nasolacrimal ducts of all animals after 4 weeks. In only one of five cases, the coated stent became partially occluded after 2 months. These animals were free of clinical symptoms. After 3 months, at least three out of five stents still opened to forced irrigation and only one stent was completely blocked. Dislocation of the stents was not observed. Refinement of the stent surface and stent design improves the results of nasolacrimal duct stenting in this animal model. Implantation of hydrophilic-coated S-shaped stents is highly superior to conventional mushroom-type stents and noncoated stent types. Hydrophilic coating seems to prevent foreign-body reactions, resulting in maximized stent patency.« less

In vitro comparison of intracranial stent visibility using various concentrations of gadolinium contrast agent under 1.5 T and 3 T MR angiography.

PubMed

Chiang, Chen-Hua; Tseng, Ying-Chi; Chen, Ai-Chi; Huang, Yen-Lin; Chen, David Yen-Ting; Chen, Chi-Jen; Lin, Yen-Kuang; Hsu, Hui-Ling

2017-04-01

MR angiography (MRA) is an increasingly used evaluation method following intracranial stenting. However, the various artifacts created by the stent limit this technique. The purpose of this study was to investigate the effects of various concentrations of gadolinium contrast agent on the visibility and signal characteristics of two stents using the a contrast enhanced MRA technique. Two intracranial stents (Enterprise and Helistent) were placed in polyvinyl chloride tubes as vascular phantoms. They were filled with six different doses of gadolinium contrast agent (1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 mmol/L dimeglumine gadopentetate, respectively) and imaged using 3 T and 1.5 T MR systems. Relative in-stent signal (RIS) was calculated and artificial luminal narrowing (ALN) was obtained using pixel by pixel analysis. The Enterprise stent, performed in both 1.5 T and 3 T MR systems, showed mean RIS values much less than those for the Helistent for all different doses of gadolinium solution. Increased gadolinium concentration resulted in a gradual reduction in RIS values in the Enterprise group. Also, ALN in the Enterprise group showed no or little change with various gadolinium doses. The Enterprise stent demonstrated good luminal visibility regardless of gadolinium concentration. The relative in-stent signals were more predictable in the Enterprise stent with various doses of gadolinium. Therefore, the Enterprise stent has been shown to provide better in-stent visibility compared with the Helistent using various gadolinium doses. 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/.

Acute stent recoil and optimal balloon inflation strategy: an experimental study using real-time optical coherence tomography.

PubMed

Kitahara, Hideki; Waseda, Katsuhisa; Yamada, Ryotaro; Otagiri, Kyuhachi; Tanaka, Shigemitsu; Kobayashi, Yuhei; Okada, Kozo; Kume, Teruyoshi; Nakagawa, Kaori; Teramoto, Tomohiko; Ikeno, Fumiaki; Yock, Paul G; Fitzgerald, Peter J; Honda, Yasuhiro

2016-06-12

Our aim was to evaluate stent expansion and acute recoil at deployment and post-dilatation, and the impact of post-dilatation strategies on final stent dimensions. Optical coherence tomography (OCT) was performed on eight bare metal platforms of drug-eluting stents (3.0 mm diameter, n=6 for each) during and after balloon inflation in a silicone mock vessel. After nominal-pressure deployment, a single long (30 sec) vs. multiple short (10 sec x3) post-dilatations were performed using a non-compliant balloon (3.25 mm, 20 atm). Stent areas during deployment with original delivery systems were smaller in stainless steel stents than in cobalt-chromium and platinum-chromium stents (p<0.001), whereas subsequent acute recoil was comparable among the three materials. At post-dilatation, acute recoil was greater in cobalt-chromium and platinum-chromium stents than in stainless steel stents (p<0.001), resulting in smaller final stent areas in cobalt-chromium and platinum-chromium stents than in stainless steel stents (p<0.001). In comparison between conventional and latest-generation cobalt-chromium stents, stent areas were not significantly different after both deployment and post-dilatation. With multiple short post-dilatations, acute recoil was significantly improved from first to third short inflation (p<0.001), achieving larger final area than a single long inflation, despite stent materials/designs (p<0.001). Real-time OCT revealed significant acute recoil in all stent types. Both stent materials/designs and post-dilatation strategies showed a significant impact on final stent expansion.

[Complications and the management of fully covered retrievable metal stent placement in benign tracheal stenosis].

PubMed

Wang, Zheng-yu; Wang, Yong-li; Chen, Guang-li; Liang, Xi-hong; Wang, Zhen-chang; Ma, Jian-zhong; Wu, Guang-zhong; Zhang, Xiao-ping

2012-11-01

To study complications and the management of the use of covered retrievable expandable metallic stents in the treatment of benign tracheal stenosis. Fully covered retrievable metal stents were placed in 21 patients with benign tracheal stenosis. Stent-related complications and the management were reviewed and analysed. Twenty-eight fully covered retrievable metallic stents were successfully placed fluoroscopically in 21 patients. Stents were removed 4 - 12 months [mean (5.5 ± 2.2) mouths] after placement in all patients. Stent-related complications included granulation tissue (n = 18), stent migration (n = 4), stent expectoration (n = 2), halitosis (n = 8), mucous retention (n = 21) and mucus plugging (n = 1). Granulation tissue was removed with a carbon dioxide laser in 2 patients. Stents were replaced for 2 times and 3 times respectively in 2 patients after stent migration and stent expectoration. An additional stent was placed in 2 patients after stent migration. Symptom of halitosis was relieved after prolonged course of systemic antibiotics treatment in 8 patients. Symptom of mucous retention was relieved with nebulized saline and N-acetylcysteine saline inhalation. Mucous plug was expelled after severe coughing after suctioning using an aspirator in one patient. There were statistically significant differences in stricture diameter, rank of tachypnea and pulmonary function (FEV(1)) in all 21 patients before stent insertion and after stents removal. No patient has experienced recurrence during the follow-up period of 1 - 36 months [mean (23.2 ± 8.0) months]. Fully covered retrievable metallic stent may be a safe and effective in benign tracheal stenosis. Stent-related complications may be effectively managed.

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.

Antegrade Ureteral Stenting is a Good Alternative for the Retrograde Approach.

PubMed

van der Meer, Rutger W; Weltings, Saskia; van Erkel, Arian R; Roshani, Hossain; Elzevier, Henk W; van Dijk, Lukas C; van Overhagen, Hans

2017-07-01

Double J (JJ) stents for treating obstructive ureteral pathology are generally inserted through a retrograde route with cystoscopic guidance. Antegrade percutaneous insertion using fluoroscopy can be performed alternatively but is less known. Indications, success rate and complications of antegrade ureteral stenting were evaluated. Data of consecutive patients in which antegrade ureteral stenting was performed were retrospectively analysed using the radiology information system and patient records. Patient characteristics, details of the antegrade JJ stent insertion procedure and registered complications were collected. Furthermore, it was investigated if prior to the antegrade procedure a retrograde attempt for JJ stent insertion was performed. Total 130 attempts for antegrade JJ stent insertion were performed in 100 patients. A percutaneous nephrostomy catheter had already been placed in the majority of kidneys (n = 109) for initial treatment of hydronephrosis. Most prevelant indication for a JJ stent was obstructive ureteral pathology due to malignancy (n = 63). A JJ stent was successfully inserted in 125 of 130 procedures. In 21 cases, previous retrograde ureteral stenting had failed but, subsequent antegrade ureteral stenting was successful. There were 8 procedure related complications; 6 infections, 1 false tract and 1 malposition. Antegrade percutaneous insertion of a JJ stent is a good alternative for retrograde insertion.

Bilateral metal stents for hilar biliary obstruction using a 6Fr delivery system: outcomes following bilateral and side-by-side stent deployment.

PubMed

Law, Ryan; Baron, Todd H

2013-09-01

Controversy exists on optimal endoscopic management for palliation of malignant hilar obstruction, with advocates for metal "side-by-side" (SBS) and "stent-in-stent" (SIS) techniques. We sought to evaluate the technical feasibility, efficacy, and outcomes of bilateral biliary self-expanding metal stents (SEMS) for treatment of malignant hilar obstruction using a stent with a 6Fr delivery system. This was a single-center, retrospective review of all patients who underwent bilateral placement of Zilver® biliary SEMS for malignant hilar obstruction from January 2010 to August 2012. Patients underwent endoscopic retrograde cholangiopancreatography with placement of stents using either the SIS or SBS stent techniques. Twenty-four patients (19 men, mean age 63 years) underwent bilateral stenting for malignant hilar obstruction during the study period. Seventeen and seven patients underwent the SBS and SIS technique, respectively. Cholangiocarcinoma (n=14) was the most common cause of hilar obstruction. Initial technical success was achieved in 24/24 (100%) of patients; however, 12 (50%) patients required re-intervention during the study period (median 98 days). Comparison of the SBS and SIS groups revealed no statistical difference with respect to need for re-intervention (P=0.31), successful re-intervention (P=0.60), or procedural length (P=0.89). Use of bilateral Zilver® SEMS in either the SBS or SIS configuration is safe, technically feasible, and effective for drainage of malignant hilar obstruction; however, duration of stent patency and procedure-free survival remain variable.

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

The use of JJ stent in the management of deep endometriosis lesion, affecting or potentially affecting the ureter: a review of our practice.

PubMed

Weingertner, A S; Rodriguez, B; Ziane, A; Gibon, E; Thoma, V; Osario, F; Haddad, C; Wattiez, A

2008-08-01

With the increasing number of operative laparoscopies performed for the treatment of deep pelvic endometriosis, technical difficulties and risk of complications inevitably increase. We report our experience using JJ stents, in women treated for deep pelvic endometriosis, with regard to prevention and management of ureteral lesions. Descriptive retrospective analysis between March 2004 and March 2007. Department of Obstetrics and Gynaecology, University Hospital, Strasbourg, France. Cases of women who underwent laparoscopic surgery for severe endometriosis and who needed a JJ stent in their management were recorded. Laparoscopic surgery was performed at the Department of Obstetrics and Gynaecology at CMCO-SIHCUS and Hautepierre Hospitals, Strasbourg, which are referral centres in the treatment of deep endometriosis. To evaluate the contribution of JJ stent in the prevention and management of ureteral lesions from endometriotic origin and/or iatrogenic origin in women treated for deep pelvic endometriosis. A total of 145 women had surgery for deep pelvic endometriosis. Seventeen (11.7%) women had a JJ ureteral stent inserted. In 82.4% of women, the stent was inserted pre- or peroperatively. We noted three ureteral complications, of which only one needed management by laparotomy. Except in extreme cases, management of ureteral endometriosis should be performed laparoscopically. Ureteral lesions whether iatrogenic, or secondary to endometriotic disease, can be treated by cystoscopy, JJ stent and laparoscopy. The combination of these three elements is the optimal management and is unlikely to cause subsequent complications. Laparotomy and its associated morbidity should be avoided.

Experimental evaluation of efficacy and healing response of everolimus-eluting stents in the familial hypercholesterolemic swine model: a comparative study of bioabsorbable versus durable polymer stent platforms.

PubMed

Tellez, Armando; Seifert, Paul S; Donskoy, Elina; Sushkova, Natalia; Pennington, Douglas E; Milewski, Krzysztof; Krueger, Christian G; Kaluza, Greg L; Eppihimer, Michael J; Huibregtse, Barbara A; Dawkins, Keith D; Granada, Juan F

2014-05-01

The utility of animal models for the prediction of drug-eluting stent (DES) efficacy in human clinical trials is still unclear. The familial hypercholesterolemic swine (FHS) model has been shown to induce a human-like neointimal response to bare metal stent (BMS) implantation. However, its utility to discriminate efficacy signals following DES implantation is unknown. In this study, we aimed to test the efficacy and healing response of several everolimus-eluting stent (EES) platforms in the coronary territory of the FHS. A total of 19 EES platforms (SYNERGY=6, SYNERGY½-dose=7, and PROMUS Element=6) and an identical BMS control (Element=6) were implanted into the coronary arteries of nine FHS. All implants were performed under intravascular ultrasound guidance using a 1.2 : 1 overstretch ratio. At 30 days, the vascular response to the implant was evaluated by quantitative coronary angiography, optical coherence tomography, and histology. At 28 days, all EES platforms showed a significant decrease in angiographic late lumen loss (between 27 and 37%) compared with the BMS control group. This finding was confirmed both by optical coherence tomography (mean neointimal thickness=28-42% reduction) and by histology (mean neointimal thickness=44-55% reduction). All EES platforms showed similar degrees of neointimal inhibition. The presence of moderate to severe para-strut inflammation was observed in 83% of the stent sections in the BMS group compared with 28.6% in the SYNERGY½-dose group and 0% in the SYNERGY and PROMUS groups (P=0.0002). There was a 68-95% reduction in MMP9 expression in the media in all EES platforms compared with the BMS controls. The presence of mild to moderate para-strut fibrin deposits ranged from 66.7 to 83.4% in all EES platforms compared with 16.7% in the EBMS group. The FHS coronary injury model showed the efficacy of several EES platforms compared with an identical BMS control. Everolimus eluted from different polymeric platforms showed lower levels of inflammation and slightly higher fibrin deposits compared with BMS controls.

Medical Devices; Gastroenterology-Urology Devices; Classification of the Metallic Biliary Stent System for Benign Strictures. Final order.

PubMed

2016-07-13

The Food and Drug Administration (FDA) is classifying the metallic biliary stent system for benign strictures into class II (special controls). The special controls that will apply to the device are identified in this order and will be part of the codified language for the metallic biliary stent system for benign strictures' classification. The Agency is classifying the device into class II (special controls) in order to provide a reasonable assurance of safety and effectiveness of the device.

[Technical feasibility of the implantation of a monorail stent system into the renal arteries without pre-dilatation].

PubMed

Neumann, C; Gschwendtner, M; Karnel, F; Mair, J; Dorffner, G; Dorffner, R

2005-01-01

To evaluate the technical feasibility of the implantation of the monorail RX Herculink system into the renal arteries without pre-dilatation. Forty-two patients (mean age 71 years) from four centers with a total of 44 renal artery stenoses underwent implantation of the RX Herculink stent. The mean grade of the stenosis was 83.8 %, the mean length 7.5 mm. The stenoses were ostial in 38 cases and in immediate proximity to the ostium in 6 cases. The mean follow-up-period was 57 weeks (24 - 176 weeks). In 42 cases, the implantation was successful without pre-dilatation. In 2 cases, pre-dilatation was carried out. In none of the cases, detachment of the stent from the balloon was observed. In one stenosis with a length of 17 mm, implantation of two stents was performed. In 9 cases, post-dilatation with a larger balloon or higher balloon pressure was necessary. Residual stenoses exceeding 30 % were not observed. Two patients developed local bleeding at the puncture site. During the follow-up, restenoses were observed in 5 stents after 26 to 126 weeks, which necessitated a second intervention in 3 cases (PTA in 2 cases, re-stenting in 1 case). The primary patency rate after 6 and 12 months was 0.92 +/- 0.056 according to Kaplan-Meier, the secondary patency rate after 6 and 12 months was 1.0 +/- 0.0. Implantation of the RX Herculink stent system into the renal arteries without pre-dilatation is technically feasible and safe. Even without pre-dilatation, the stent-system can be advanced through the stenosis without detachment. The complication rate is low. Our clinical results are comparable to previous studies.

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

PubMed

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

2015-08-17

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

[Anesthetic management of tracheobronchial stent insertion in patients who underwent laser resection, balloon dilatation and tracheostomy in advance].

PubMed

Hirai, Akiko; Hirose, Yoshifumi; Gamoh, Masahiro; Satoh, Minako

2005-10-01

We report successful management of tracheobronchial stent insertion under general anesthesia. In thirty-two cases, tracheobronchial stent insertion was performed under general anesthesia. The technique for airway management was chosen depending on the type of stent or the constriction level of the airway portion. We employed tracheostomy in order to avoid repeated intubations during the insertion of Dumon or Dynamic stent. In case of severe airway stenosis, laser resection or balloon dilatation was performed before stent insertion. We had 32 successful cases in 36 trials. Four trials failed due to insufficient expansion in one, mismatches of stent angle in one and pneumomediastinum in one. There was no exacerbation of respiratory condition in failed cases. There was no case who needed percutaneous cardiopulmonary support system. We managed tracheobronchial stent insertion under general anesthesia. Both the airway expansion by laser resection or balloon dilatation before stent insertion and also the insertion of Dumon or Dynamic stent through a tracheostomy were helpful strategies. These techniques facilitated more definitive airway maintenance and stable anesthetic management.

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.

A quantitative study on magnesium alloy stent biodegradation.

PubMed

Gao, Yuanming; Wang, Lizhen; Gu, Xuenan; Chu, Zhaowei; Guo, Meng; Fan, Yubo

2018-06-06

Insufficient scaffolding time in the process of rapid corrosion is the main problem of magnesium alloy stent (MAS). Finite element method had been used to investigate corrosion of MAS. However, related researches mostly described all elements suffered corrosion in view of one-dimensional corrosion. Multi-dimensional corrosions significantly influence mechanical integrity of MAS structures such as edges and corners. In this study, the effects of multi-dimensional corrosion were studied using experiment quantitatively, then a phenomenological corrosion model was developed to consider these effects. We implemented immersion test with magnesium alloy (AZ31B) cubes, which had different numbers of exposed surfaces to analyze differences of dimension. It was indicated that corrosion rates of cubes are almost proportional to their exposed-surface numbers, especially when pitting corrosions are not marked. The cubes also represented the hexahedron elements in simulation. In conclusion, corrosion rate of every element accelerates by increasing corrosion-surface numbers in multi-dimensional corrosion. The damage ratios among elements with the same size are proportional to the ratios of corrosion-surface numbers under uniform corrosion. The finite element simulation using proposed model provided more details of changes of morphology and mechanics in scaffolding time by removing 25.7% of elements of MAS. The proposed corrosion model reflected the effects of multi-dimension on corrosions. It would be used to predict degradation process of MAS quantitatively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Applying value stream mapping techniques to eliminate non-value-added waste for the procurement of endovascular stents.

PubMed

Teichgräber, Ulf K; de Bucourt, Maximilian

2012-01-01

OJECTIVES: To eliminate non-value-adding (NVA) waste for the procurement of endovascular stents in interventional radiology services by applying value stream mapping (VSM). The Lean manufacturing technique was used to analyze the process of material and information flow currently required to direct endovascular stents from external suppliers to patients. Based on a decision point analysis for the procurement of stents in the hospital, a present state VSM was drawn. After assessment of the current status VSM and progressive elimination of unnecessary NVA waste, a future state VSM was drawn. The current state VSM demonstrated that out of 13 processes for the procurement of stents only 2 processes were value-adding. Out of the NVA processes 5 processes were unnecessary NVA activities, which could be eliminated. The decision point analysis demonstrated that the procurement of stents was mainly a forecast driven push system. The future state VSM applies a pull inventory control system to trigger the movement of a unit after withdrawal by using a consignment stock. VSM is a visualization tool for the supply chain and value stream, based on the Toyota Production System and greatly assists in successfully implementing a Lean system. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Predictors of the patency of self-expandable metallic stents in malignant gastroduodenal obstruction.

PubMed

Kim, Seung Han; Chun, Hoon Jai; Yoo, In Kyung; Lee, Jae Min; Nam, Seung Joo; Choi, Hyuk Soon; Kim, Eun Sun; Keum, Bora; Seo, Yeon Seok; Jeen, Yoon Tae; Lee, Hong Sik; Um, Soon Ho; Kim, Chang Duck

2015-08-14

To investigate the predictive factors of self-expandable metallic stent patency after stent placement in patients with inoperable malignant gastroduodenal obstruction. A total of 116 patients underwent stent placements for inoperable malignant gastroduodenal obstruction at a tertiary academic center. Clinical success was defined as acceptable decompression of the obstructive lesion within the malignant gastroduodenal neoplasm. We evaluated patient comorbidities and clinical statuses using the World Health Organization's scoring system and categorized patient responses to chemotherapy using the Response Evaluation Criteria in Solid Tumors criteria. We analyzed the relationships between possible predictive factors and stent patency. Self-expandable metallic stent placement was technically successful in all patients (100%), and the clinical success rate was 84.2%. In a multivariate Cox proportional hazards model, carcinoembryonic antigen (CEA) levels were correlated with a reduction in stent patency [P = 0.006; adjusted hazard ratio (aHR) = 2.92, 95%CI: 1.36-6.25]. Palliative chemotherapy was statistically associated with an increase in stent patency (P = 0.009; aHR = 0.27, 95%CI: 0.10-0.72). CEA levels can easily be measured at the time of stent placement and may help clinicians to predict stent patency and determine the appropriate stent procedure.

Single-step simultaneous side-by-side placement of a self-expandable metallic stent with a 6-Fr delivery system for unresectable malignant hilar biliary obstruction: a feasibility study.

PubMed

Kawakubo, Kazumichi; Kawakami, Hiroshi; Kuwatani, Masaki; Kudo, Taiki; Abe, Yoko; Kawahata, Shuhei; Kubo, Kimitoshi; Kubota, Yoshimasa; Sakamoto, Naoya

2015-02-01

Bilateral self-expandable metallic stent (SEMS) placement for the management of unresectable malignant hilar biliary obstruction (UMHBO) is technically challenging to perform using the existing metallic stents with thick delivery systems. The recently developed 6-Fr delivery systems could facilitate a single-step simultaneous side-by-side placement through the accessory channel of the duodenoscope. The aim of this study was to evaluate the feasibility of this procedure. Between May and September 2013, 13 consecutive patients with UMHBO underwent a single-step simultaneous side-by-side placement of SEMS with the 6-Fr delivery system. The technical success rate, stent patency, and rate of complications were evaluated from the prospectively collected database. Technical success was achieved in 11 (84.6%, 95% confidence interval [CI]: 57.8-95.8) patients. The median procedure time was 25 min. Early and late complications were observed in 23% (one segmental cholangitis and two liver abscesses) and 15% (one segmental cholangitis and one cholecystitis) patients, respectively. Median dysfunction free patency was 263 days (95% CI: 37-263). Five patients (38%) experienced stent occlusion that was successfully managed by endoscopic stent placement. A single-step simultaneous side-by-side placement of SEMS with a 6-Fr delivery system was feasible for the management of UMHBO. © 2014 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

Robot-Assisted Antegrade In-Situ Fenestrated Stent Grafting

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

Riga, Celia V., E-mail: c.riga@imperial.ac.uk; Bicknell, Colin D.; Wallace, Daniel

2009-05-15

To determine the technical feasibility of a novel approach of in-situ fenestration of aortic stent grafts by using a remotely controlled robotic steerable catheter system in the porcine model. A 65-kg pig underwent robot-assisted bilateral antegrade in-situ renal fenestration of an abdominal aortic stent graft with subsequent successful deployment of a bare metal stent into the right renal artery. A 16-mm iliac extension covered stent served as the porcine aortic endograft. Under fluoroscopic guidance, the graft was punctured with a 20-G customized diathermy needle that was introduced and kept in place by the robotic arm. The needle was exchanged formore » a 4 x 20 mm cutting balloon before successful deployment of the renal stent. Robot-assisted antegrade in-situ fenestration is technically feasible in a large mammalian model. The robotic system enables precise manipulation, stable positioning, and minimum instrumentation of the aorta and its branches while minimizing radiation exposure.« less

Antegrade Ureteral Stenting is a Good Alternative for the Retrograde Approach

PubMed Central

van der Meer, Rutger W.; Weltings, Saskia; van Erkel, Arian R.; Roshani, Hossain; Elzevier, Henk W.; van Dijk, Lukas C.; van Overhagen, Hans

2017-01-01

Background/Aims Double J (JJ) stents for treating obstructive ureteral pathology are generally inserted through a retrograde route with cystoscopic guidance. Antegrade percutaneous insertion using fluoroscopy can be performed alternatively but is less known. Indications, success rate and complications of antegrade ureteral stenting were evaluated. Methods Data of consecutive patients in which antegrade ureteral stenting was performed were retrospectively analysed using the radiology information system and patient records. Patient characteristics, details of the antegrade JJ stent insertion procedure and registered complications were collected. Furthermore, it was investigated if prior to the antegrade procedure a retrograde attempt for JJ stent insertion was performed. Results Total 130 attempts for antegrade JJ stent insertion were performed in 100 patients. A percutaneous nephrostomy catheter had already been placed in the majority of kidneys (n = 109) for initial treatment of hydronephrosis. Most prevelant indication for a JJ stent was obstructive ureteral pathology due to malignancy (n = 63). A JJ stent was successfully inserted in 125 of 130 procedures. In 21 cases, previous retrograde ureteral stenting had failed but, subsequent antegrade ureteral stenting was successful. There were 8 procedure related complications; 6 infections, 1 false tract and 1 malposition. Conclusion Antegrade percutaneous insertion of a JJ stent is a good alternative for retrograde insertion. PMID:28785193

The BioStent: novel concept for a viable stent structure.

PubMed

Weinandy, Stefan; Rongen, Lisanne; Schreiber, Fabian; Cornelissen, Christian; Flanagan, Thomas Cormac; Mahnken, Andreas; Gries, Thomas; Schmitz-Rode, Thomas; Jockenhoevel, Stefan

2012-09-01

Percutaneous stenting of occluded peripheral vessels is a well-established technique in clinical practice. Unfortunately, the patency rates of small-caliber vessels after stenting remain unsatisfactory. The aim of the BioStent concept is to overcome in-stent restenosis by excluding the diseased vessel segment entirely from the blood stream, in addition to providing an intact endothelial cell layer. The concept combines the principles of vascular tissue engineering with a self-expanding stent: casting of the stent within a cellularized fibrin gel structure, followed by bioreactor conditioning, allows complete integration of the stent within engineered tissue. Small-caliber BioStents (Ø=6 mm; n=4) were produced by casting a nitinol stent within a thin fibrin/vascular smooth muscle cell (vSMC) mixture, followed by luminal endothelial cell seeding, and conditioning of the BioStent within a bioreactor system. The potential remodeling of the fibrin component into tissue was analyzed using routine histological methods. Scanning electron microscopy was used to assess the luminal endothelial cell coverage following the conditioning phase and crimping of the stent. The BioStent was shown to be noncytotoxic, with no significant effect on cell proliferation. Gross and microscopic analysis revealed complete integration of the nitinol component within a viable tissue structure. Hematoxylin and eosin staining revealed a homogenous distribution of vSMCs throughout the thickness of the BioStent, while a smooth, confluent luminal endothelial cell lining was evident and not significantly affected by the crimping/release process. The BioStent concept is a platform technology offering a novel opportunity to generate a viable, self-expanding stent structure with a functional endothelial cell lining. This platform technology can be transferred to different applications depending on the luminal cell lining required.

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.

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

PubMed

Chandra, Praveen; Kumar, Tarun

2014-01-01

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

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

PubMed

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

2011-08-01

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

Bacteriology of urinary tract infection associated with indwelling J ureteral stents.

PubMed

Kehinde, Elijah O; Rotimi, Vincent O; Al-Hunayan, Adel; Abdul-Halim, Hamdy; Boland, Fareeda; Al-Awadi, Khaleel A

2004-11-01

To investigate the microorganisms responsible for urinary tract infection (UTI) and stent colonization in patients with indwelling J ureteral stents and to compare the antimicrobial susceptibility pattern of the isolates from urine and J stents in order to establish the etiologic agents of bacteriuria and colonized stents in such patients and provide baseline data on an antibiotic policy for the urology unit. Midstream urine from 250 patients requiring J stent insertion was investigated microbiologically prior to stent insertion and on the day of stent removal. After stent removal, 3 to 5 cm of the tip located in the bladder was also sent for culture. Patients' bio-data and underlying diseases were documented. Those with no known systemic diseases ("normal patients") were also studied as controls. Of the 250 patients studied, 152 (61%) were normal, while 27 (11%), 53 (21%), and 18 (7%) had diabetes mellitus (DM), chronic renal failure (CRF), and diabetic nephropathy (DN), respectively. The mean duration of stent retention was 27 days. All microbial isolates were tested for their susceptibility to a panel of 10 antibiotics. Twelve patients (5%) before stent insertion and 42 patients (17%; P < 0.001) on the day of stent removal had positive urine cultures. One hundred four stents (42%) were culture positive. Of the 104 patients with positive stent cultures, in 62 patients (60%), urine culture was sterile. The commonest isolates were Escherichia coli, Enterococcus spp., Staphylococcus spp., Pseudomonas, and Candida spp. On the day of stent removal, urine culture was positive in 28% of the normal patients compared with 57% (P = 0.11), 78% (P < 0.001), and 62% (P < 0.001) of patients with CRF, DM, and DN, respectively. Stent isolates were more resistant to antibiotics than the organism isolated before stent insertion. An indwelling J ureteral stent carries a significant risk of bacteriuria and stent colonization. The sensitivity of urine culture to stent colonization is low, and therefore, a negative culture does not rule out a colonized stent. Bacteria cultured from urine after stent insertion and from the stents are more resistant to antibiotics than are those cultured from urine before stent insertion. Norfloxacin or ciprofloxacin is recommended as prophylaxis prior to stent insertion, and an aminoglycoside can be added to treat symptomatic patients with severe infections.

1-year clinical outcomes of diabetic patients treated with everolimus-eluting bioresorbable vascular scaffolds: a pooled analysis of the ABSORB and the SPIRIT trials.

PubMed

Muramatsu, Takashi; Onuma, Yoshinobu; van Geuns, Robert-Jan; Chevalier, Bernard; Patel, Tejas M; Seth, Ashok; Diletti, Roberto; García-García, Hector M; Dorange, Cécile C; Veldhof, Susan; Cheong, Wai-Fung; Ozaki, Yukio; Whitbourn, Robert; Bartorelli, Antonio; Stone, Gregg W; Abizaid, Alexandre; Serruys, Patrick W

2014-05-01

The aim of this study was to evaluate 1-year clinical outcomes of diabetic patients treated with the Absorb bioresorbable vascular scaffold (BVS). Clinical outcomes of diabetic patients after BVS implantation have been unreported. This study included 101 patients in the ABSORB Cohort B trial and the first consecutive 450 patients with 1 year of follow-up in the ABSORB EXTEND trial. A total of 136 diabetic patients were compared with 415 nondiabetic patients. In addition, 882 diabetic patients treated with everolimus-eluting metal stents (EES) in pooled data from the SPIRIT trials (SPIRIT FIRST [Clinical Trial of the Abbott Vascular XIENCE V Everolimus Eluting Coronary Stent System], SPIRIT II [A Clinical Evaluation of the XIENCE V Everolimus Eluting Coronary Stent System], SPIRIT III [Clinical Trial of the XIENCE V Everolimus Eluting Coronary Stent System (EECSS)], SPIRIT IV Clinical Trial [Clinical Evaluation of the XIENCE V Everolimus Eluting Coronary Stent System]) were used for the comparison by applying propensity score matching. The primary endpoint was a device-oriented composite endpoint (DoCE), including cardiac death, target vessel myocardial infarction, and target lesion revascularization at 1-year follow-up. The cumulative incidence of DoCE did not differ between diabetic and nondiabetic patients treated with the BVS (3.7% vs. 5.1%, p = 0.64). Diabetic patients treated with the BVS had a similar incidence of the DoCE compared with diabetic patients treated with EES in the matched study group (3.9% for the BVS vs. 6.4% for EES, p = 0.38). There were no differences in the incidence of definite or probable scaffold/stent thrombosis (0.7% for both diabetic and nondiabetic patients with the BVS; 1.0% for diabetic patients with the BVS vs. 1.7% for diabetic patients with EES in the matched study group). In the present analyses, diabetic patients treated with the BVS showed similar rates of DoCEs compared with nondiabetic patients treated with the BVS and diabetic patients treated with EES at 1-year follow-up. (ABSORB Clinical Investigation, Cohort B; NCT00856856; ABSORB EXTEND Clinical Investigation; NCT01023789; Clinical Trial of the Abbott Vascular XIENCE V Everolimus Eluting Coronary Stent System [SPIRIT FIRST]; NCT00180453; A Clinical Evaluation of the XIENCE V Everolimus Eluting Coronary Stent System [SPIRIT II]; NCT00180310; Clinical Trial of the XIENCE V Everolimus Eluting Coronary Stent System [EECSS] [SPIRIT III]; NCT00180479; Clinical Evaluation of the XIENCE V Everolimus Eluting Coronary Stent System [SPIRIT IV Clinical Trial]; NCT00307047). Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

78 FR 53773 - Select Updates for Non-Clinical Engineering Tests and Recommended Labeling for Intravascular...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-30

...] Select Updates for Non-Clinical Engineering Tests and Recommended Labeling for Intravascular Stents and... Engineering Tests and Recommended Labeling for Intravascular Stents and Associated Delivery Systems.'' FDA has developed this guidance to inform the coronary and peripheral stent industry about selected updates to FDA's...

The use of balloon-expandable metallic stents in the treatment of pediatric tracheomalacia and bronchomalacia.

PubMed

Furman, R H; Backer, C L; Dunham, M E; Donaldson, J; Mavroudis, C; Holinger, L D

1999-02-01

To evaluate the use of balloon-expandable metallic stents in the treatment of children with tracheomalacia and bronchomalacia in whom conventional therapy has failed. Retrospective case series. Tertiary pediatric otolaryngology and cardiothoracic surgery referral center. Six patients were identified as having undergone bronchoscopic placement of metallic balloon-expandable stents between 1994 and 1997. The age at stent placement, prior surgical interventions, and indications for and sites of stent placement were noted. Also, the complications related to stent placement and the current airway status of the patients were reviewed. Twelve balloon-expandable metallic angioplasty stents (Palmaz; Johnson & Johnson Interventional Systems Co, Warren, NJ) were placed bronchoscopically in 6 patients. Six stents were placed in the lower trachea, and 6 were placed in the main bronchi. The stents were balloon expanded under fluoroscopic guidance. Discontinuation of mechanical ventilation. The age at stent placement ranged from 1.5 to 38 months (mean age at placement, 10 months). The indications for stent placement were (1) tracheomalacia or bronchomalacia, (2) pericardial patch or slide tracheoplasty failure, and (3) bronchomalacia caused by tetralogy of Fallot and large pulmonary arteries. The primary complication of stent placement was postoperative granulation tissue formation. One patient required the removal of 2 tracheal stents because of granulation tissue formation. There were 2 deaths in the series, 1 possibly related to stent placement. Four of the 6 patients were weaned from mechanical ventilation, and 3 experienced prolonged relief of airway obstruction. Metallic balloon-expandable stents are effective in relieving lower tracheomalacia and bronchomalacia in select patients. Only patients in whom conventional therapy has failed should be considered for stent placement.

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.

Predictors of the patency of self-expandable metallic stents in malignant gastroduodenal obstruction

PubMed Central

Kim, Seung Han; Chun, Hoon Jai; Yoo, In Kyung; Lee, Jae Min; Nam, Seung Joo; Choi, Hyuk Soon; Kim, Eun Sun; Keum, Bora; Seo, Yeon Seok; Jeen, Yoon Tae; Lee, Hong Sik; Um, Soon Ho; Kim, Chang Duck

2015-01-01

AIM: To investigate the predictive factors of self-expandable metallic stent patency after stent placement in patients with inoperable malignant gastroduodenal obstruction. METHODS: A total of 116 patients underwent stent placements for inoperable malignant gastroduodenal obstruction at a tertiary academic center. Clinical success was defined as acceptable decompression of the obstructive lesion within the malignant gastroduodenal neoplasm. We evaluated patient comorbidities and clinical statuses using the World Health Organization’s scoring system and categorized patient responses to chemotherapy using the Response Evaluation Criteria in Solid Tumors criteria. We analyzed the relationships between possible predictive factors and stent patency. RESULTS: Self-expandable metallic stent placement was technically successful in all patients (100%), and the clinical success rate was 84.2%. In a multivariate Cox proportional hazards model, carcinoembryonic antigen (CEA) levels were correlated with a reduction in stent patency [P = 0.006; adjusted hazard ratio (aHR) = 2.92, 95%CI: 1.36-6.25]. Palliative chemotherapy was statistically associated with an increase in stent patency (P = 0.009; aHR = 0.27, 95%CI: 0.10-0.72). CONCLUSION: CEA levels can easily be measured at the time of stent placement and may help clinicians to predict stent patency and determine the appropriate stent procedure. PMID:26290640

Update on the everolimus-eluting coronary stent system: results and implications from the SPIRIT clinical trial program

PubMed Central

Kirchner, R Michael; Abbott, J Dawn

2009-01-01

Drug-eluting stents (DES) have had a major impact in interventional cardiology. Compared to bare metal stents, they significantly reduce restenosis and the need for target vessel revascularization. Four DES are available in the US, the first-generation sirolimus-eluting (Cypher®) and paclitaxel-eluting (Taxus®) stents and later approved second-generation everolimus-eluting (Xience V®) and zotarolimus-eluting (Endeavor®) stents. The Xience V stent was approved on the basis of clinical efficacy and safety data from 3 studies in the SPIRIT clinical trial program. Within this trial series, the Xience V was superior to its bare metal stent counterpart, the Vision® stent, and noninferior to the paclitaxel-eluting stent for target vessel failure at 9 months. This review provides a comprehensive assessment of the data derived from both the pre- and post-approval randomized controlled trials and registry studies of Xience V that comprise the SPIRIT clinical trial program including recently published mid-term outcomes. The implications of the results in terms of interventional practice will be discussed. PMID:20057901

Endoscopic management of unresectable malignant gastroduodenal obstruction with a nitinol uncovered metal stent: A prospective Japanese multicenter study

PubMed Central

Sasaki, Reina; Sakai, Yuji; Tsuyuguchi, Toshio; Nishikawa, Takao; Fujimoto, Tatsuya; Mikami, Shigeru; Sugiyama, Harutoshi; Yokosuka, Osamu

2016-01-01

AIM: To determine the safety and efficacy of endoscopic duodenal stent placement in patients with malignant gastric outlet obstruction. METHODS: This prospective, observational, multicenter study included 39 consecutive patients with malignant gastric outlet obstruction. All patients underwent endoscopic placement of a nitinol, uncovered, self-expandable metal stent. The primary outcome was clinical success at 2 wk after stent placement that was defined as improvement in the Gastric Outlet Obstruction Scoring System score relative to the baseline. RESULTS: Technical success was achieved in all duodenal stent procedures. Procedure-related complications occurred in 4 patients (10.3%) in the form of mild pneumonitis. No other morbidities or mortalities were observed. The clinical success rate was 92.3%. The mean survival period after stent placement was 103 d. The mean period of stent patency was 149 d and the patency remained acceptable for the survival period. Stent dysfunction occurred in 3 patients (7.7%) on account of tumor growth. CONCLUSION: Endoscopic management using duodenal stents for patients with incurable malignant gastric outlet obstruction is safe and improved patients’ quality of life. PMID:27076769

Does the novel delivery system for the STENTYS self-apposing coronary stent increase the risk of stent edge dissections? Optical coherence tomography post stent findings.

PubMed

Lu, Huangling; Kalkman, Deborah N; Grundeken, Maik J; Tijssen, Jan G P; Wykrzykowska, Joanna J; de Winter, Robbert J; Koch, Karel T

2018-02-01

With optical coherence tomography (OCT), details of arterial injuries during percutaneous coronary intervention can be assessed accurately. There might be an increased risk of stent edge dissections with the novel delivery system for the STENTYS stent. We evaluated the prevalence of stent edge dissections using the novel Xposition delivery device as compared with the conventional delivery device. A total of 38 patients who were treated with the self-apposing STENTYS stent and with OCT assessment at our center were retrospectively analysed. Twenty patients were treated using the Xposition- and 18 using the conventional delivery device. OCT was performed according to study protocol. Frames with poor quality were excluded. A total of 12(18%) dissections were detected, 7(20%) in the Xposition delivery device group, and 5(15%) in the conventional group (p = 1). Using the Xposition delivery device 4(33%) dissections were found proximally, using the conventional delivery device 3(25%) (p = ns). Mean longitudinal dissection length was 2.07 ± 1.80mm, 8(67%) appeared as flaps, 4(33%) as cavities. Morphometric parameters were comparable in both groups. Detailed OCT assessment of stent edge dissections was possible, which revealed no large differences using the Xposition delivery device as compared with conventional delivery device, however large studies are warranted.

Percutaneous biliary drainage using open cell stents for malignant biliary hilar obstruction.

PubMed

Ahn, Sun Jun; Bae, Jae Ik; Han, Tae Sun; Won, Je Hwan; Kim, Ji Dae; Kwack, Kyu-Sung; Lee, Jae Hee; Kim, Young Chul

2012-01-01

To evaluate the feasibility, safety and the effectiveness of the complex assembly of open cell nitinol stents for biliary hilar malignancy. During the 10 month period between January and October 2007, 26 consecutive patients with malignant biliary hilar obstruction underwent percutaneous insertion of open cell design nitinol stents. Four types of stent placement methods were used according to the patients' ductal anatomy of the hilum. We evaluated the technical feasibility of stent placement, complications, patient survival, and the duration of stent patency. Bilobar biliary stent placement was conducted in 26 patients with malignant biliary obstruction-T (n = 9), Y (n = 7), crisscross (n = 6) and multiple intersecting types (n = 4). Primary technical success was obtained in 24 of 26 (93%) patients. The crushing of the 1st stent during insertion of the 2nd stent occurred in two cases. Major complications occurred in 2 of 26 patients (7.7%). One case of active bleeding from hepatic segmental artery and one case of sepsis after procedure occurred. Clinical success was achieved in 21 of 24 (87.5%) patients, who were followed for a mean of 141.5 days (range 25-354 days). The mean primary stent patency period was 191.8 days and the mean patient survival period was 299 days. Applying an open cell stent in the biliary system is feasible, and can be effective, especially in multiple intersecting stent insertions in the hepatic hilum.

Shrinking the Supply Chain for Implantable Coronary Stent Devices.

PubMed

Moore, Sean S; O'Sullivan, Kevin J; Verdecchia, Francesco

2016-02-01

Stenting treatments for the management of disease in the heart, arterial and venous systems, biliary ducts, urethras, ureters, oesophageal tract and prostate have made enormous technical advances since their introduction into clinical use. The progression from metallic to polymer based bio-absorbable stents, coupled with the advances in additive manufacturing techniques, present a unique opportunity to completely re-envision the design, manufacture, and supply chain of stents. This paper looks at current stenting trends and proposes a future where the stent supply chain is condensed from ~150 days to ~20 min. The Cardiologist therefore has the opportunity to become a designer, manufacturer and user with patients receiving custom stents specific to their unique pathology that will be generated, delivered and deployed in the Cath-lab. The paper will outline this potentially revolutionary development and consider the technical challenges that will need to be overcome in order to achieve these ambitious goals. A high level overview of the generating eluting stents in situ program-GENESIS-is outlined including some early experimental work.

Cost analysis of prophylactic intraoperative cystoscopic ureteral stents in gynecologic surgery.

PubMed

Fanning, James; Fenton, Bradford; Jean, Geraldine Marie; Chae, Clara

2011-12-01

Prophylactic intraoperative ureteral stent placement is performed to decrease operative ureteric injury, though few data are available on the effectiveness of this procedure, and no data are available on its cost. To analyze the cost of prophylactic intraoperative cystoscopic ureteral stents in gynecologic surgery. All cases of prophylactic ureteral stent placement performed in gynecologic surgery during a 1-year period were identified and retrospectively reviewed through the electronic medical records database of Summa Health System. Costs were obtained through the Healthcare Cost Accounting System. The principles of cost-effective analysis were used (ie, explicit and detailed descriptions of costs and cost-effectiveness statistics). Importantly, we evaluated cost and not charges or financial model estimates. In addition, we obtained the contribution margins (ie, the hospital's net profit or loss) for prophylactic ureteral stent placement. Other gynecologic procedures were also analyzed. Among 792 major inpatient gynecologic procedures, 18 cases of prophylactic intraoperative ureteral stents were identified. Median costs were as follows: additional cost of prophylactic intraoperative ureteral stenting, $1580; additional cost of surgical resources, $770; cost of ureteral catheters, $427; cost of surgeons, $383. The contribution margins per case for various gynecologic surgical procedures were as follows: oophorectomy, $2804 profit; abdominal hysterectomy, $2649 profit; laparoscopically assisted vaginal hysterectomy (LAVH), $1760 profit. When intraoperative ureteral stenting was added, the contribution margins changed to the following: oophorectomy, $782 profit; abdominal hysterectomy, $627 profit; LAVH, $262 loss. Overall, the contribution margin profit was decreased by about 85%, from $2400 to $380. Prophylactic intraoperative ureteral stenting in gynecologic surgery decreases a hospital's contribution margin. Because of the expense of this procedure, as well as scientific data suggesting a lack of effectiveness, the authors argue that prophylactic intraoperative ureteral stenting should not be used in gynecologic surgery to decrease operative ureteric injury.

78 FR 35284 - Medical Devices; Availability of Safety and Effectiveness Summaries for Premarket Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-12

.... Stent Graft System. P040046, FDA-2013-M-0255 Allergan Natrelle[supreg] 410 February 20, 2013. Highly... Vascular, Resolute Integrity February 22, 2013. Inc. Zotarolimus-Eluting Coronary Stent System. P100030...

Endoscopic ultrasound-guided biliary drainage using a newly designed metal stent with a thin delivery system: a preclinical study in phantom and porcine models.

PubMed

Minaga, Kosuke; Kitano, Masayuki; Itonaga, Masahiro; Imai, Hajime; Miyata, Takeshi; Yamao, Kentaro; Tamura, Takashi; Nuta, Junya; Warigaya, Kenji; Kudo, Masatoshi

2017-12-08

This study was designed to evaluate the feasibility and safety of a newly designed self-expandable metal stent for endoscopic ultrasound-guided biliary drainage (EUS-BD) when it was delivered via three different stent delivery systems: a 7.5Fr delivery catheter with a bullet-shaped tip (7.5Fr-bullet), a 7Fr catheter with a bullet-shaped tip (7Fr-bullet), or a 7Fr catheter with a tee-shaped tip (7Fr-tee). This experimental study utilized a porcine model of biliary dilatation involving ten pigs. In the animal study, technical feasibility and clinical outcomes of the stent when placed with each of the delivery systems were examined. In addition, a phantom model was used to measure the resistance of these delivery systems to advancement. Phantom experiments showed that, compared with 7Fr-bullet, 7Fr-tee had less resistance force to the advancement of the stent delivery system. EUS-BD was technically successful in all ten pigs. Fistulous tract dilation was necessary in 100% (2/2), 75% (3/4), and 0% (0/4) of the pigs that underwent EUS-BD using 7.5Fr-bullet, 7Fr-bullet, and 7Fr-tee, respectively. There were no procedure-related complications. Our newly designed metal stent may be feasible and safe for EUS-BD, particularly when delivered by 7Fr-tee, because it eliminates the need for fistulous tract dilation.

78 FR 17415 - Medical Devices; Availability of Safety and Effectiveness Summaries for Premarket Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-21

..., FDA-2012-M-1012 Bolton Medical Inc... Relay[supreg] September 21, 2012. Thoracic Stent-Graft with Plus........ Ovation Abdominal October 5, 2012. Stent Graft System. P120007, FDA-2012-M-1066 Gen-Probe, Inc........ Medtronic Vascular... Valiant[supreg] October 26, 2012. Thoracic Stent Graft with the Captivia Delivery...

Design considerations and quantitative assessment for the development of percutaneous mitral valve stent.

PubMed

Kumar, Gideon Praveen; Cui, Fangsen; Phang, Hui Qun; Su, Boyang; Leo, Hwa Liang; Hon, Jimmy Kim Fatt

2014-07-01

Percutaneous heart valve replacement is gaining popularity, as more positive reports of satisfactory early clinical experiences are published. However this technique is mostly used for the replacement of pulmonary and aortic valves and less often for the repair and replacement of atrioventricular valves mainly due to their anatomical complexity. While the challenges posed by the complexity of the mitral annulus anatomy cannot be mitigated, it is possible to design mitral stents that could offer good anchorage and support to the valve prosthesis. This paper describes four new Nitinol based mitral valve designs with specific features intended to address migration and paravalvular leaks associated with mitral valve designs. The paper also describes maximum possible crimpability assessment of these mitral stent designs using a crimpability index formulation based on the various stent design parameters. The actual crimpability of the designs was further evaluated using finite element analysis (FEA). Furthermore, fatigue modeling and analysis was also done on these designs. One of the models was then coated with polytetrafluoroethylene (PTFE) with leaflets sutured and put to: (i) leaflet functional tests to check for proper coaptation of the leaflet and regurgitation leakages on a phantom model and (ii) anchorage test where the stented valve was deployed in an explanted pig heart. Simulations results showed that all the stents designs could be crimped to 18F without mechanical failure. Leaflet functional test results showed that the valve leaflets in the fabricated stented valve coapted properly and the regurgitation leakage being within acceptable limits. Deployment of the stented valve in the explanted heart showed that it anchors well in the mitral annulus. Based on these promising results of the one design tested, the other stent models proposed here were also considered to be promising for percutaneous replacement of mitral valves for the treatment of mitral regurgitation, by virtue of their key features as well as effective crimping. These models will be fabricated and put to all the aforementioned tests before being taken for animal trials. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

First-in-man study evaluating the safety and efficacy of a second generation biodegradable polymer sirolimus-eluting stent in the treatment of patients with de novo coronary lesions: clinical, Angiographic, and OCT outcomes of CREDIT-1.

PubMed

Wang, Geng; Sun, Zhongwei; Jin, Quanmin; Xu, Kai; Li, Yi; Wang, Xiaozeng; Ma, Yingyan; Liu, Haiwei; Zhao, Xin; Wang, Bin; Deng, Jie; Guan, Shaoyi; Ge, Meiling; Wang, Xiaoyan; Xu, Bo; Han, Yaling

2015-03-01

To evaluate the preliminary safety and efficacy of the EXCEL II stent system. Although the first biodegradable polymer drug-eluting stent (BP-DES), EXCEL, was launched nearly a decade ago, in-stent restenosis and stent thrombosis remain pertinent clinical problems in practice. A new cobalt-chromium BP-DES EXCEL II has been developed with the aim of improving stent safety and efficacy. Forty-five patients with single de novo native coronary lesions were enrolled and randomized to two groups in a 2:1 ratio, the 4-month follow-up group (n = 30) and the 12-month follow-up group (n = 15). All patients underwent percutaneous coronary intervention (PCI) with the EXCEL II stent system. Quantitative coronary angiography (QCA) and optical coherence tomography (OCT) were used to assess coronary vasculature at the designated 4- or 12-month follow-up. The primary outcome was major adverse cardiac events (MACE) at 30 days post-PCI. No MACE, thrombotic events, or target lesion failure was found in the 45 patients during the 12-month follow-up. There was no significant difference (P > 0.05) between the two groups in terms of in-stent and in-segment late lumen loss (LLL). No in-stent and in-segment restenosis was found in either group. At follow-up, the ratio of >10% uncovered struts per lesion was 26.67% in the 4-month group and 0% in the 12-month group (P < 0.05). Neointimal coverage in the 12-month group was significantly better than in the 4-month group (98.58% vs. 93.51%, P < 0.01). This first-in-man study demonstrates promising feasibility, safety, and efficacy of EXCEL II stents. These stents were found to have rapid endothelialization and low LLL rates at 4 and 12 months after implantation. © 2015 Wiley Periodicals, Inc.

A Novel Partially Covered Self-Expandable Metallic Stent with Proximal Flare in Patients with Malignant Gastric Outlet Obstruction.

PubMed

Takahara, Naminatsu; Isayama, Hiroyuki; Nakai, Yousuke; Yoshida, Shuntaro; Saito, Tomotaka; Mizuno, Suguru; Yagioka, Hiroshi; Kogure, Hirofumi; Togawa, Osamu; Matsubara, Saburo; Ito, Yukiko; Yamamoto, Natsuyo; Tada, Minoru; Koike, Kazuhiko

2017-07-15

Endoscopic placement of self-expandable metal stents (SEMSs) has emerged as a palliative treatment for malignant gastric outlet obstruction (GOO). Although covered SEMSs can prevent tumor ingrowth, frequent migration of covered SEMSs may offset their advantages in preventing tumor ingrowth. We conducted this multicenter, single-arm, retrospective study at six tertiary referral centers to evaluate the safety and efficacy of a partially covered SEMS with an uncovered large-bore flare at the proximal end as an antimigration system in 41 patients with symptomatic malignant GOO. The primary outcome was clinical success, and the secondary outcomes were technical success, stent dysfunction, adverse events, and survival after stent placement. The technical and clinical success rates were 100% and 95%, respectively. Stent dysfunctions occurred in 17 patients (41%), including stent migration in nine (23%), tumor ingrowth in one (2%), and tumor overgrowth in four (10%). Two patients (5%) developed adverse events: one pancreatitis and one perforation. No procedure-related death was observed. A novel partially covered SEMS with a large-bore flare proximal end was safe and effective for malignant GOO but failed to prevent stent migration. Further research is warranted to develop a covered SEMS with an optimal antimigration system.

75 FR 38532 - Medical Devices; Availability of Safety and Effectiveness Summaries for Premarket Approval...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-02

... LLIAC March 5, FDA-2010-M-0135 Scientific PREMOUNTED STENT SYSTEM 2010 Corp. P090006 Medtronic COMPLETE SE VASCULAR March 17, FDA-2010-M-0158 Vascular STENT SYSTEM 2010 II. Electronic Access Persons with...

Structural Mechanics Predictions Relating to Clinical Coronary Stent Fracture in a 5 Year Period in FDA MAUDE Database

PubMed Central

Everett, Kay D.; Conway, Claire; Desany, Gerard J.; Baker, Brian L.; Choi, Gilwoo; Taylor, Charles A.; Edelman, Elazer R.

2016-01-01

Endovascular stents are the mainstay of interventional cardiovascular medicine. Technological advances have reduced biological and clinical complications but not mechanical failure. Stent strut fracture is increasingly recognized as of paramount clinical importance. Though consensus reigns that fractures can result from material fatigue, how fracture is induced and the mechanisms underlying its clinical sequelae remain ill-defined. In this study, strut fractures were identified in the prospectively maintained Food and Drug Administration's (FDA) Manufacturer and User Facility Device Experience Database (MAUDE), covering years 2006–2011, and differentiated based on specific coronary artery implantation site and device configuration. These data, and knowledge of the extent of dynamic arterial deformations obtained from patient CT images and published data, were used to define boundary conditions for 3D finite element models incorporating multimodal, multi-cycle deformation. The structural response for a range of stent designs and configurations was predicted by computational models and included estimation of maximum principal, minimum principal and equivalent plastic strains. Fatigue assessment was performed with Goodman diagrams and safe/unsafe regions defined for different stent designs. Von Mises stress and maximum principal strain increased with multimodal, fully reversed deformation. Spatial maps of unsafe locations corresponded to the identified locations of fracture in different coronary arteries in the clinical database. These findings, for the first time, provide insight into a potential link between patient adverse events and computational modeling of stent deformation. Understanding of the mechanical forces imposed under different implantation conditions may assist in rational design and optimal placement of these devices. PMID:26467552

Structural Mechanics Predictions Relating to Clinical Coronary Stent Fracture in a 5 Year Period in FDA MAUDE Database.

PubMed

Everett, Kay D; Conway, Claire; Desany, Gerard J; Baker, Brian L; Choi, Gilwoo; Taylor, Charles A; Edelman, Elazer R

2016-02-01

Endovascular stents are the mainstay of interventional cardiovascular medicine. Technological advances have reduced biological and clinical complications but not mechanical failure. Stent strut fracture is increasingly recognized as of paramount clinical importance. Though consensus reigns that fractures can result from material fatigue, how fracture is induced and the mechanisms underlying its clinical sequelae remain ill-defined. In this study, strut fractures were identified in the prospectively maintained Food and Drug Administration's (FDA) Manufacturer and User Facility Device Experience Database (MAUDE), covering years 2006-2011, and differentiated based on specific coronary artery implantation site and device configuration. These data, and knowledge of the extent of dynamic arterial deformations obtained from patient CT images and published data, were used to define boundary conditions for 3D finite element models incorporating multimodal, multi-cycle deformation. The structural response for a range of stent designs and configurations was predicted by computational models and included estimation of maximum principal, minimum principal and equivalent plastic strains. Fatigue assessment was performed with Goodman diagrams and safe/unsafe regions defined for different stent designs. Von Mises stress and maximum principal strain increased with multimodal, fully reversed deformation. Spatial maps of unsafe locations corresponded to the identified locations of fracture in different coronary arteries in the clinical database. These findings, for the first time, provide insight into a potential link between patient adverse events and computational modeling of stent deformation. Understanding of the mechanical forces imposed under different implantation conditions may assist in rational design and optimal placement of these devices.

Interventional radiology and the use of metal stents in nonvascular clinical practice: a systematic overview.

PubMed

Pron, G; Common, A; Simons, M; Ho, C S

1999-05-01

The intent of this systematic overview was to describe the clinical role of metal stents in nonvascular health care interventions and the level of evidence supporting their use. Structured searches of Medline were conducted and limited to original peer-reviewed articles published in English. Clinical practice involving metal stents was reported in more than 109 clinical series involving 4,753 patients. Stents were placed mainly for palliation of malignant biliary, esophageal, and airway obstruction in patients who were untreatable or had surgically unresectable lesions. Assessment of these interventions has so far centered on safety and technical success. Efficacy, quality of life, and costing factors were not routinely reported. Randomized trial evidence was available but limited; six randomized trials involving metal stents have been reported. Three trials involved biliary malignant obstruction, and all three reported metal stent (132 patients) palliation to be superior to plastic stent palliation (136 patients) based on longer patency and lower reintervention costs. Safety and complication differences between stents, however, were inconsistent across trials. In three trials involving esophageal malignant obstruction, metal stent (82 patients) palliation was reported to be superior to plastic stent (41 patients), based on lower complication and reintervention rates, and superior to laser therapy (18 patients), based on better dysphagia relief. Use of metal stents has been reported for obstructed ducts and passageways of most body systems. There is, however, limited controlled trial evidence confirming the advantages of their use over plastic stents or other forms of treatment.

Stent design favorably influences the vascular response in normal porcine coronary arteries.

PubMed

Carter, A J; Scott, D; Rahdert, D; Bailey, L; De Vries J; Ayerdi, K; Turnlund, T; Jones, R; Virmani, R; Fischell, T A

1999-03-01

The purpose of this study was to compare the arterial response following implantation of a stainless-steel, balloon-expandable, tubular slotted stent with that of a novel computer-designed, multi-cellular stent in normal porcine coronary arteries. Intracoronary stent placement has evolved into the primary strategy for percutaneous revascularization of symptomatic coronary arterial lesions. Presently there is intense interest in developing new stent designs to improve stent delivery and biocompatability. Computer-assisted design was utilized to develop a balloon-expandable stent with symmetric expansion properties, uniform arterial wall coverage, longitudinal flexibility and radial strength. Quantitative coronary angiography and histological assessment of the stented arteries was used to evaluate the acute and chronic vascular responses to a stainless-steel, balloon-expandable, tubular slotted stent as compared to the computer-designed BX stent in the normolipemic swine. Forty stents (24 BX, 16 tubular slotted) were implanted in 19 miniature swine at a mean inflation pressure of 9 atm using identical delivery systems. Eight of the BX and none of the tubular slotted stents were post-dilated with a non-compliant balloon at 12-14 atm. The mean stent-to-artery ratio was similar for the BX (1.03 +/- 0.06) and tubular slotted (1.04 +/- 0.11; p = 0.59) designs. Protrusion or asymmetric radial flaring of a strut at the stent margin was present in 1 of 23 BX stents (4.3%) and 10 of 15 tubular slotted stents (66.7%; p < 0.0001). The mean arterial injury score was significantly less for the BX stent (0.2 +/- 0.2) as compared with the tubular slotted stents (0.4 +/- 0.4; p = 0.025). At 3 days, thrombus area was similar for the BX and tubular slotted designs (0.42 +/- 0.16 mm2 versus 0.44 +/- 0.18 mm2, respectively; p = 0.88). The mean neointimal area was significantly less for the BX at 2 months (1.09 +/- 0.25 mm2 versus 2.93 +/- 2.26 mm2 in the tubular slotted stent) and at 6 months (1.10 +/- 0.26 mm2 versus 2.07 +/- 0.65 mm2 in the tubular slotted stent; p = 0.01), resulting in approximately 50% less in-stent stenosis. The arterial response to a balloon-expandable stent can be favorably influenced by computer-assisted modification of design in an experimental model. Further study is warranted to determine the impact of stent design upon clinical in-stent restenosis.

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.

Experimental Study of Poly-l-Lactic Acid Biodegradable Stents in Normal Canine Bile Ducts

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

Yamamoto, Kiyosei, E-mail: yamakiyo@zg7.so-net.ne.jp; Yoshioka, Tetsuya; Furuichi, Kinya

Purpose: This study was designed to clarify the advantages of biodegradable stents in terms of mucosal reaction and biodegradation after placement. We designed a biodegradable stent and assessed stent degradation and changes in the normal bile ducts of dogs. Methods: The biodegradable stent is a balloon-expandable Z stent consisting of poly-l-lactic acid (PLLA) with a diameter of 6 mm and a length of 15 mm. We assessed four groups of three beagle dogs each at 1, 3, 6, and 9 months of follow-up. After evaluating stent migration by radiography and stent and bile duct patency by cholangiography, the dogs weremore » sacrificed to remove the bile duct together with the stent. The bile duct lumen was examined macroscopically and histologically, and the stent degradation was examined macroscopically and by scanning electron microscopy (SEM). Results: Bile duct obstruction was absent and none of the stents migrated. Macroscopic evaluation showed moderate endothelial proliferation in the bile ducts at the implant sites at 3 and 6 months and a slight change at 9 months. Slight mononuclear cell infiltration was histologically identified at all time points and epithelial hyperplasia that was moderate at 3 months was reduced to slight at 6 and 9 months. Stent degradation was macroscopically evident in all animals at 9 months and was proven by SEM in two dogs at 6 months and in all of them at 9 months. Conclusions: Our results suggest that PLLA bioabsorbable stents seems to be useful for implantation in the biliary system with further investigation.« less

Stent-based nitric oxide delivery reducing neointimal proliferation in a porcine carotid overstretch injury model.

PubMed

Hou, Dongming; Narciso, Hugh; Kamdar, Kirti; Zhang, Ping; Barclay, Bruce; March, Keith L

2005-01-01

The effects of nitric acid (NO) on vessel response to injury include the inhibition of platelet adhesion, platelet aggregation, leukocyte adhesion and smooth muscle cell proliferation. Releasing NO from a stent might reduce the clinical problem of restenosis. The present study was designed to examine whether an NO-eluting covered stent can prevent neointimal formation in a porcine carotid overstretch injury model. The interior of a self-expanding polytetrafluoroethylene (ePTFE)-covered aSpire stent was coated with silicone, which contained 23.6 microg or 54.5 microg sodium nitroprusside (SNP, NO-releasing compound). The stent was implanted into carotid artery. Six pigs were implanted with stents, one high-dose SNP and one uncoated control, following balloon overstretch injury of the carotid artery with a balloon-to-artery ratio of 1.3:1. No local or systemic toxicity was evidenced in the six pigs after carotid artery implantation with either low- or high-dose stents within a week. At day 28, the mean intimal thickness was 0.12 +/- 0.05 mm for NO-eluting stents and 0.43 +/- 0.09 mm for uncoated stents (p = 0.008). The mean neointimal area was reduced from 2.40 +/- 0.39 mm2 for control stents to 0.49 +/- 0.16 mm2 for NO-eluting stents (p < 0.0001), which resulted in a 24% reduction of angiographic vessel narrowing. The NO-eluting ePTFE-covered stent is feasible and effectively reduces in-stent neointimal hyperplasia at 28 days in a porcine carotid overstretch model.

Stent-mediated gene and drug delivery for cardiovascular disease and cancer: A brief insight.

PubMed

Krishnagopal, Akshaya; Reddy, Aakash; Sen, Dwaipayan

2017-05-01

This review concisely recapitulates the different existing modes of stent-mediated gene/drug delivery, their considerable advancement in clinical trials and a rationale for other merging new technologies such as nanotechnology and microRNA-based therapeutics, in addition to addressing the limitations in each of these perpetual stent platforms. Over the past decade, stent-mediated gene/drug delivery has materialized as a hopeful alternative for cardiovascular disease and cancer in contrast to routine conventional treatment modalities. Regardless of the phenomenal recent developments achieved by coronary interventions and cancer therapies that employ gene and drug-eluting stents, practical hurdles still remain a challenge. The present review highlights the limitations that each of the existing stent-based gene/drug delivery system encompasses and therefore provides a vision for the future with respect to discovering an ideal stent therapeutic platform that would circumvent all the practical hurdles witnessed with the existing technology. Further study of the improvisation of next-generation drug-eluting stents has helped to overcome the issue of restenosis to some extent. However, current stent formulations fall short of the anticipated clinically meaningful outcomes and there is an explicit need for more randomized trials aiming to further evaluate stent platforms in favour of enhanced safety and clinical value. Gene-eluting stents may hold promise in contributing new ideas for stent-based prevention of in-stent restenosis through genetic interventions by capitalizing on a wide variety of molecular targets. Therefore, the central consideration directs us toward finding an ideal stent therapeutic platform that would tackle all of the gaps in the existing technology. Copyright © 2017 John Wiley & Sons, Ltd.

Tracheobronchial Polyflex stents for the management of benign refractory hypopharyngeal strictures.

PubMed

Silva, Rui Almeida; Mesquita, Nuno; Nunes, Pedro Pimentel; Cardoso, Elisabete; Pinto, Ricardo Marcos; Dias, Luís Moreira

2012-02-14

To describe a modified technique for placement of a tracheobronchial self-expanding plastic stent (SEPS) in patients with benign refractory hypopharyngeal strictures in order to improve dysphagia and allow stricture remodeling. A case series of four consecutive patients with complex hypopharyngeal strictures after combined therapy for laryngeal cancer, previously submitted to multiple sessions of dilation without lasting improvement, is presented. All patients underwent placement of a small diameter and unflared tracheobronchial SEPS. Main outcome measurements were improvement of dysphagia and avoiding of repeated dilation. The modified introducer system allowed an easy and technically successful deployment of the tracheobronchial Polyflex stent through the stricture. All four patients developed complications related to stent placement. Two patients had stent migration (one proximal and one distal), two patients developed phanryngocutaneous fistulas and all patients with stents in situ for more than 8 wk had hyperplastic tissue growth at the upper end of the stent. Stricture recurrence was observed at 4 wk follow-up after stent removal in all patients. Although technically feasible, placement of a tracheobronchial SEPS is associated with a high risk of complications. Small diameter stents must be kept in place for longer than 3 mo to allow adequate time for stricture remodeling.

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.

A prospective, randomized evaluation of a novel everolimus-eluting coronary stent: the PLATINUM (a Prospective, Randomized, Multicenter Trial to Assess an Everolimus-Eluting Coronary Stent System [PROMUS Element] for the Treatment of Up to Two de Novo Coronary Artery Lesions) trial.

PubMed

Stone, Gregg W; Teirstein, Paul S; Meredith, Ian T; Farah, Bruno; Dubois, Christophe L; Feldman, Robert L; Dens, Joseph; Hagiwara, Nobuhisa; Allocco, Dominic J; Dawkins, Keith D

2011-04-19

We sought to evaluate the clinical outcomes with a novel platinum chromium everolimus-eluting stent (PtCr-EES) compared with a predicate cobalt chromium everolimus-eluting stent (CoCr-EES) in patients undergoing percutaneous coronary intervention (PCI). Randomized trials have demonstrated an excellent safety and efficacy profile for the CoCr-EES. The PtCr-EES uses the identical antiproliferative agent and polymer but with a novel platinum chromium scaffold designed for enhanced deliverability, vessel conformability, side-branch access, radiopacity, radial strength, and fracture resistance. A total of 1,530 patients undergoing PCI of 1 or 2 de novo native lesions were randomized at 132 worldwide sites to CoCr-EES (n = 762) or PtCr-EES (n = 768). The primary endpoint was the 12-month rate of target lesion failure (TLF), the composite of target vessel-related cardiac death, target vessel-related myocardial infarction (MI), or ischemia-driven target lesion revascularization (TLR) in the per-protocol population (patients who received ≥1 assigned study stent), powered for noninferiority. The 12-month rate of TLF in the per-protocol population occurred in 2.9% versus 3.4% of patients assigned to CoCr-EES versus PtCr-EES, respectively (difference: 0.5%, 95% confidence interval: -1.3% to 2.3%, p(noninferiority) = 0.001, p(superiority) = 0.60). By intention-to-treat, there were no significant differences between CoCr-EES and PtCr-EES in the 12-month rates of TLF (3.2% vs. 3.5%, p = 0.72), cardiac death or MI (2.5% vs. 2.0%, p = 0.56), TLR (1.9% vs. 1.9%, p = 0.96), or Academic Research Consortium definite or probable stent thrombosis (0.4% vs. 0.4%, p = 1.00). In this large-scale, prospective, single-blind randomized trial, a novel PtCr-EES was noninferior to the predicate CoCr-EES for TLF, with nonsignificant differences in measures of safety and efficacy through 12-month follow-up after PCI. Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Impact of different aortic valve calcification patterns on the outcome of transcatheter aortic valve implantation: A finite element study.

PubMed

Sturla, Francesco; Ronzoni, Mattia; Vitali, Mattia; Dimasi, Annalisa; Vismara, Riccardo; Preston-Maher, Georgia; Burriesci, Gaetano; Votta, Emiliano; Redaelli, Alberto

2016-08-16

Transcatheter aortic valve implantation (TAVI) can treat symptomatic patients with calcific aortic stenosis. However, the severity and distribution of the calcification of valve leaflets can impair the TAVI efficacy. Here we tackle this issue from a biomechanical standpoint, by finite element simulation of a widely adopted balloon-expandable TAVI in three models representing the aortic root with different scenarios of calcific aortic stenosis. We developed a modeling approach realistically accounting for aortic root pressurization and complex anatomy, detailed calcification patterns, and for the actual stent deployment through balloon-expansion. Numerical results highlighted the dependency on the specific calcification pattern of the "dog-boning" of the stent. Also, local stent distortions were associated with leaflet calcifications, and led to localized gaps between the TAVI stent and the aortic tissues, with potential implications in terms of paravalvular leakage. High stresses were found on calcium deposits, which may be a risk factor for stroke; their magnitude and the extent of the affected regions substantially increased for the case of an "arc-shaped" calcification, running from commissure to commissure. Moreover, high stresses due to the interaction between the aortic wall and the leaflet calcifications were computed in the annular region, suggesting an increased risk for annular damage. Our analyses suggest a relation between the alteration of the stresses in the native anatomical components and prosthetic implant with the presence and distribution of relevant calcifications. This alteration is dependent on the patient-specific features of the calcific aortic stenosis and may be a relevant indicator of suboptimal TAVI results. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Strategies for the Management of SVC Stent Migration into the Right Atrium

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

Taylor, J. D., E-mail: drjeremytaylor@yahoo.co.uk; Lehmann, E. D.; Belli, A.-M.

Purpose. Stent migration into the right atrium is a potentially fatal complication of stenting in the venous system and is most likely to occur during the treatment of superior vena cava obstruction. Endovascular approaches that can salvage this hazardous situation are described and the keys to successful treatment are highlighted. Materials and Methods. Four different strategies are reviewed: (1) snaring the stent directly, (2) angioplasty balloon-assisted snaring of the stent, (3) guide wire-assisted snaring of the stent, and (4) superior vena cava-to-inferior vena cava bridging stent. Results. These techniques have been employed in the successful management of four cases. Nomore » short- or long-term complications as a result of these maneuvers have been identified. Additional treatment of the underlying disease was possible at the same time in each case. Conclusion. We conclude that prompt management of right atrial stent migration is essential and can be successfully achieved by a variety of 'bale-out' techniques which are within the technical range of most interventional radiologists.« less

Clinical and angiographic outcomes after stent-assisted coiling of cerebral aneurysms with Enterprise and Neuroform stents: a comparative analysis of the literature.

PubMed

King, Brent; Vaziri, Sasha; Singla, Amit; Fargen, Kyle M; Mocco, J

2015-12-01

The most widely used intracranial stents for stent-assisted coiling are Neuroform (NEU) and Enterprise stents (ENT). This study compares published outcomes between the ENT and NEU coil-assist systems and comments on the published safety and efficacy of stent-assisted coiling in general. A literature search was performed through PubMed for all published series of ENT or NEU stent-assisted coiling of cerebral aneurysms from 2004 to 2014. All studies including 10 or more published cases of stent-assisted coiling with ENT or NEU were included. 47 studies met the inclusion criteria, containing 4238 aneurysms in 4039 patients. 2111 aneurysms were treated with NEU and 2127 were treated with ENT. Mean follow-up was 14.1 months. Overall, thromboembolic events occurred in 6.4% of aneurysms, intracranial hemorrhage (ICH) in 2.6%, permanent morbidity in 3.9%, and mortality in 2.3%. Initial and final 100% angiographic occlusion was seen in 53% and 69% of patients, respectively. Deployment failures (p<0.001), ICH (p=0.001), mortality among all patients (p=0.03), and recanalization (p=0.02) were more commonly reported in NEU treated aneurysms. The ENT system was also associated with higher reported complete occlusion at follow-up (p<0.001). This literature review represents the largest and most robust comparison of stent-assisted coiling devices to date, containing over 4200 aneurysms in more than 4000 patients. Comparative analyses demonstrate that both devices are reported to be safe and effective with comparable permanent morbidity. 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/

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

PubMed

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

2015-10-01

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

Reproducibility of the Carpet View system: a novel technical solution for display and off line analysis of OCT images.

PubMed

Gabriele, Alex; Marco, Valeria; Gatto, Laura; Paoletti, Giulia; Di Vito, Luca; Castriota, Fausto; Romagnoli, Enrico; Ricciardi, Andrea; Prati, Francesco

2014-10-01

The optical coherence tomography (OCT) evaluation of the stent anatomy requires the inspection of sequential cross section (CS). However stent coils cannot be appreciated in the conventional format as the OCT CS simply display stent struts, that are poorly representative of the stent architecture. The aim of the present study was to validate a new software (Carpet View), which unfolds the stented segment, reconstructing it as an open structure and displaying the stent meshwork. 21 patients were studied with frequency domain OCT after the deployment of different stents: seven bio-absorbable scaffolds (Dream), seven bare metal stent (Vision/Multilink8), seven drug eluting stent (Cre8). Conventional CS reconstructions were post-processed with the Carpet View software and analyzed by the same reader twice (intra-observer variability) and by two different readers (inter-observer variability). A small average difference in the number of all struts was obtained with the two methods (conventional vs carpet view reconstruction). Using the carpet view, high intra-observer and inter-observer correlations were found for the number of struts obtained in each coil. The Pearson correlation values were 0.98 (p = 0.0001) and 0.96 (p = 0.0001) respectively. The same number of coils was found when analyses were repeated by the same reader or by a different reader whilst mild differences in the count of stent junctions were reported. The Carpet View can be used to address the stent geometry with high reproducibility. This approach enables the matching of the same stent portion during serial time points and promises to improve the stent assessment.

Adult Patent Ductus Arteriosus: Treatment with a Stent-Graft

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

Munoz, J.J., E-mail: jjmrc@telefonica.net; Urbaneja, A.; Gonzalez, N.

We present the case of a 63-year-old woman with a short patent ductus arteriosus and aneurysmal pulmonary arteries who was treated by placement of a stent-graft. The technique proved simple and safe. Further research is required to improve the design of stent-grafts and their release system for use of this technique in adult patients with this disorder.

[Tracheobronchial stents: a retrospective analysis of indications, results and in particular complications].

PubMed

Tonn, H; Mall, W; Schneider, K-D; Schönhofer, B

2008-10-01

Tracheobronchial stents are inserted mainly in cases of malignant and benign airway stenosis. Further indications are esophago-tracheal fistulas, mediastinal fistulas and tracheomalacia. A retrospective analysis was conducted on patients' records, information provided by the general practitioners and relatives of the patients from July 1993 to December 2006 in the Department of Pneumology of the Heidehaus Hospital Hannover (since 6/05 Department of Pneumology and Internal Intensive Care Medicine, Oststadt-Heidehaus Hospital). During the observation period of 13 years a total of 269 stents (177 permanent, 92 temporary) were implanted in 207 patients (1.3 stents per patient). The vast majority of patients (173/207) suffered from an underlying malignancy. About half of the stents were deployed in the trachea. The median length of placement was 116 days in patients with malignancies and 313 days in patients with benign diseases. In about 40 % of the patients notable complications were observed which were directly or indirectly associated with the stents. These findings show the importance of a critical indication for stent implantation. In benign diseases a stent can remain for years inside the tracheobronchial system, if it is well tolerated in the beginning. In malignant diseases the result depends decisively on the stage of the tumour: has the stent been implanted before any other tumour therapy is started or is it an end-stage tumor with no other therapeutic option? In general, complications of stents occur quite frequently. The analysis of stent data leads to some aspects for the prevention of stent-related complications. There should be a strict indication and appropriate choice of stent material. Nevertheless, there remains an ethical dilemma in patients with end-stage disease as to whether to implant a stent or to do nothing against the tumor, because the benefit immediately after stent insertion vanishes with progression of the tumour, so causing extra complications.

Alteration of intraaneurysmal hemodynamics by placement of a self-expandable stent. Laboratory investigation.

PubMed

Tateshima, Satoshi; Tanishita, Kazuo; Hakata, Yasuhiro; Tanoue, Shin-ya; Viñuela, Fernando

2009-07-01

Development of a flexible self-expanding stent system and stent-assisted coiling technique facilitates endovascular treatment of wide-necked brain aneurysms. The hemodynamic effect of self-expandable stent placement across the neck of a brain aneurysm has not been well documented in patient-specific aneurysm models. Three patient-specific silicone aneurysm models based on clinical images were used in this study. Model 1 was constructed from a wide-necked internal carotid artery-ophthalmic artery aneurysm, and Models 2 and 3 were constructed from small wide-necked middle cerebral artery aneurysms. Neuroform stents were placed in the in vitro aneurysm models, and flow structures were compared before and after the stent placements. Flow velocity fields were acquired with particle imaging velocimetry. In Model 1, a clockwise, single-vortex flow pattern was observed in the aneurysm dome before stenting was performed. There were multiple vortices, and a very small fast flow stream was newly formed in the aneurysm dome after stenting. The mean intraaneurysmal flow velocity was reduced by approximately 23-40%. In Model 2, there was a clockwise vortex flow in the aneurysm dome and another small counterclockwise vortex in the tip of the aneurysm dome before stenting. The small vortex area disappeared after stenting, and the mean flow velocity in the aneurysm dome was reduced by 43-64%. In Model 3, a large, counterclockwise, single vortex was seen in the aneurysm dome before stenting. Multiple small vortices appeared in the aneurysm dome after stenting, and the mean flow velocity became slower by 22-51%. The flexible self-expandable stents significantly altered flow velocity and also flow structure in these aneurysms. Overall flow alterations by the stent appeared favorable for the long-term durability of aneurysm embolization. The possibility that the placement of a low-profile self-expandable stent might induce unfavorable flow patterns such as a fast flow stream in the aneurysm dome cannot be excluded.

Three-dimensional reconstruction of coronary stents in vivo based on motion compensated X-ray angiography

NASA Astrophysics Data System (ADS)

Schäfer, Dirk; Movassaghi, Babak; Grass, Michael; Schoonenberg, Gert; Florent, Raoul; Wink, Onno; Klein, Andrew J. P.; Chen, James Y.; Garcia, Joel; Messenger, John C.; Carroll, John D.

2007-03-01

The complete expansion of the stent during a percutaneous transluminal coronary angioplasty (PTCA) procedure is essential for treatment of a stenotic segment of a coronary artery. Inadequate expansion of the stent is a major predisposing factor to in-stent restenosis and acute thrombosis. Stents are positioned and deployed by fluoroscopic guidance. Although the current generation of stents are made of materials with some degree of radio-opacity to detect their location after deployment, proper stent expansion is hard to asses. In this work, we introduce a new method for the three-dimensional (3D) reconstruction of the coronary stents in-vivo utilizing two-dimensional projection images acquired during rotational angiography (RA). The acquisition protocol consist of a propeller rotation of the X-ray C-arm system of 180°, which ensures sufficient angular coverage for volume reconstruction. The angiographic projections were acquired at 30 frames per second resulting in 180 projections during a 7 second rotational run. The motion of the stent is estimated from the automatically tracked 2D coordinates of the markers on the balloon catheter. This information is used within a motion-compensated reconstruction algorithm. Therefore, projections from different cardiac phases and motion states can be used, resulting in improved signal-to-noise ratio of the stent. Results of 3D reconstructed coronary stents in vivo, with high spatial resolution are presented. The proposed method allows for a comprehensive and unique quantitative 3D assessment of stent expansion that rivals current X-ray and intravascular ultrasound techniques.

Complications of silicone stent insertion in patients with expiratory central airway collapse.

PubMed

Murgu, Septimiu D; Colt, Henri G

2007-12-01

Silicone stent insertion is an alternative treatment for expiratory central airway collapse. This study evaluates the complications (mucus plugging, migration, and granulation tissue) associated with stenting in patients who failed medical therapy and were not surgical candidates. Chart review from 15 consecutive patients treated by silicone stent insertion was done over a 2-year period. Outcomes included (1) changes in functional class, extent and severity of airway collapse (graded from 1 to 4 by using a multidimensional system), procedure- and stent-related complications at 48 hours after stent insertion; (2) frequency of stent-related complications; and (3) frequency of emergent flexible and rigid bronchoscopy (scheduled or emergent) over the follow-up period. Mean functional class and severity and extent of airway collapse significantly improved within 48 hours after treatment (p < 0.05). There were no perioperative deaths. Stent-related complications within 48 hours after stent insertion occurred in 3 patients (1 granulation, 1 migration, and 1 mucus plugging). The mean duration of follow-up for the 12 patients who underwent clinical and bronchoscopic follow-up was 188 days. Twenty-six stent-related complications (12 mucus plugs, 8 migrations, and 6 granulation tissues) were seen in 10 of the 12 patients. Five emergent flexible bronchoscopies and 14 rigid bronchoscopies (6 of which were emergent) were performed during the follow-up period. Silicone stent insertion improves functional status immediately after intervention in patients with expiratory central airway collapse, but is associated with a high rate of stent-related complications and need for repeat bronchoscopic interventions.

Implantation of a new enteral stent in obstructive colorectal cancer using interventional radiology in patients over 70 years of age.

PubMed

Miłek, Tomasz; Ciostek, Piotr

2015-07-01

Colorectal cancer is the second leading cause of death due to cancer in Poland. The traditional approach to treat patients included a surgical procedure. Irrespective of the surgical method being used, surgical treatment of malignant colorectal obstruction is associated with prolonged hospitalisation, and the postoperative mortality rate is approximately 5-11%. Due to these problems, more interest has been shown in less invasive methods. Prosthesis implantation is a leading endoscopic method used currently in palliative or preoperative treatment. To compare the results of implantation of traditional stents with the results of implantation of an own stent using minimally invasive methods. Left-sided colon obstruction due to cancer was an indication for transplantation. All patients were aged over 70 years and had serious concomitant diseases. The control group included 50 patients with colorectal cancer who received traditional stents in the period 2009-2011. Our stent covers only the internal length of a tumour. It is not equipped with anti-migration flares. To minimize the risk of migration it has a system of hooks that are responsible for permanent anchorage of the stent within the tumour mass. Implantation technical and clinical success defined as effective decompression of intestinal obstruction was 100% in both groups. There were 2 cases of stent migration in the control group. It is possible to achieve a secure surgical anastomosis after intestinal decompression. Stent implantation is fast and safe thanks to the positioning system that was used. The use of labelled hooks is a secure anti-migration solution.

In vivo imaging of superficial femoral artery (SFA) stents for deformation analysis

NASA Astrophysics Data System (ADS)

Ganguly, A.; Schneider, A.; Keck, B.; Bennett, N. R.; Fahrig, R.

2008-03-01

A high-resolution (198 μm) C-arm CT imaging system (Axiom Artis dTA, Siemens Medical Solutions, Forchheim, Germany) was optimized for imaging superficial femoral artery (SFA) stents in humans. The SFA is susceptible to the development of atherosclerotic lesions. These are typically treated with angioplasty and stent deployment. However, these stents can have a fracture rate as high as 35%. Fracture is usually accompanied by restenosis and reocclusion. The exact cause of breakage is unknown and is hypothesized to result from deforming forces due to hip and knee flexion. Imaging was performed with the leg placed in both straight and bent positions. Projection images obtained during 20 s scans with ~200° of rotation of the C-arm were back-projected to obtain 3D volumes. Using a semi-automatic software algorithm developed in-house, the stent centerlines were found and ellipses were fitted to the slice normals. Image quality was adequate for calculations in 11/13 subjects. Bending the leg was found to shorten the stents in 10/11 cases with the maximum change being 9% (12 mm in a 133 mm stent), and extend the stent in one case by 1.6%. The maximum eccentricity change was 36% with a bend angle of 72° in a case where the stent extended behind the knee.

Fabrication of hydrophobic structures on coronary stent surface based on direct three-beam laser interference lithography

NASA Astrophysics Data System (ADS)

Gao, Long-yue; Zhou, Wei-qi; Wang, Yuan-bo; Wang, Si-qi; Bai, Chong; Li, Shi-ming; Liu, Bin; Wang, Jun-nan; Cui, Cheng-kun; Li, Yong-liang

2016-05-01

To solve the problems with coronary stent implantation, coronary artery stent surface was directly modified by three-beam laser interference lithography through imitating the water-repellent surface of lotus leaf, and uniform micro-nano structures with the controllable period were fabricated. The morphological properties and contact angle (CA) of the microstructure were measured by scanning electron microscope (SEM) and CA system. The water repellency of stent was also evaluated by the contact and then separation between the water drop and the stent. The results show that the close-packed concave structure with the period of about 12 μm can be fabricated on the stent surface with special parameters (incident angle of 3°, laser energy density of 2.2 J·cm-2 and exposure time of 80 s) by using the three-beam laser at 1 064 nm, and the structure has good water repellency with CA of 120°.

In vitro biocompatibility of plasma-aided surface-modified 316L stainless steel for intracoronary stents.

PubMed

Bayram, Cem; Mizrak, Alpay Koray; Aktürk, Selçuk; Kurşaklioğlu, Hurkan; Iyisoy, Atila; Ifran, Ahmet; Denkbaş, Emir Baki

2010-10-01

316L-type stainless steel is a raw material mostly used for manufacturing metallic coronary stents. The purpose of this study was to examine the chemical, wettability, cytotoxic and haemocompatibility properties of 316L stainless steel stents which were modified by plasma polymerization. Six different polymeric compounds, polyethylene glycol, 2-hydroxyethyl methacrylate, ethylenediamine, acrylic acid, hexamethyldisilane and hexamethyldisiloxane, were used in a radio frequency glow discharge plasma polymerization system. As a model antiproliferative drug, mitomycin-C was chosen for covalent coupling onto the stent surface. Modified SS 316L stents were characterized by water contact angle measurements (goniometer) and x-ray photoelectron spectroscopy. C1s binding energies showed a good correlation with the literature. Haemocompatibility tests of coated SS 316L stents showed significant latency (t-test, p < 0.05) with respect to SS 316L and control groups in each test.

Accelerated Recovery of Endothelium Function after Stent Implantation with the Use of a Novel Systemic Nanoparticle Curcumin.

PubMed

Lu, Qi; Ye, Fang; Yang, Xiangjun; Gu, Qingqing; Wang, Peng; Zhu, Jianhua; Shen, Li; Gong, Feirong

2015-01-01

Curcumin was reported to exhibit a wide range of pharmacological effects including antioxidant, anti-inflammatory, and antiproliferative activities and significantly prevent smooth muscle cells migration. In the present study, a novel kind of curcumin loaded nanoparticles (Cur-NP) has been prepared and characterized with the aim of inhibiting inflammation formation and accelerating the healing process of the stented arteries. Cur-NP was administrated intravenously after stent implantation twice a week and detailed tissue responses were evaluated. The results demonstrated that intravenous administration of Cur-NP after stent implantation accelerated endothelial cells restoration and endothelium function recovery and may potentially be an effective therapeutic alternative to reduce adverse events for currently available drug eluting stents.

Primary endpoint results of the OMEGA Study: One-year clinical outcomes after implantation of a novel platinum chromium bare metal stent.

PubMed

Wang, John C; Carrié, Didier; Masotti, Monica; Erglis, Andrejs; Mego, David; Watkins, Matthew W; Underwood, Paul; Allocco, Dominic J; Hamm, Christian W

2015-03-01

Bare metal stents (BMS) have similar rates of death and myocardial infarction (MI) compared to drug-eluting stents (DES). DES lower repeat revascularization rates compared to BMS, but may have higher rates of late stent thrombosis (ST) potentially due to impaired endothelialization requiring longer dual anti-platelet therapy (DAPT). OMEGA evaluated a novel BMS designed to have improved deliverability and radiopacity, in comparison to currently available platforms. OMEGA was a prospective, multicenter, single-arm study enrolling 328 patients at 37 sites (US and Europe). Patients received the OMEGA stent (bare platinum chromium element stent) for the treatment of de novo native coronary artery lesions (≤28 mm long; diameter ≥2.25 mm to ≤4.50mm). The primary endpoint was 9-month target lesion failure (TLF: cardiac death, target vessel-related MI, target lesion revascularization [TLR]) compared to a prespecified performance goal (PG) based on prior generation BMS. All major cardiac events were independently adjudicated. DAPT was required for a minimum of 1 month post procedure. In the OMEGA study, the mean age was 65; 17% had diabetes mellitus. The primary endpoint was met; 9 month TLF rate was 11.5%, and the upper 1-sided 95% confidence bound of 14.79% was less than the prespecified PG of 21.2% (p<0.0001). One-year event rates were low including a TLF rate of 12.8% and an ST rate of 0.6% at 12 months. One-year outcomes of OMEGA show low rates of TLF, revascularization and ST. This supports safety and efficacy of the OMEGA BMS for the treatment of coronary artery disease. Copyright © 2015 Elsevier Inc. All rights reserved.

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 required to confirm these promising results. Copyright © 2018 European Society for Vascular Surgery. Published by Elsevier B.V. All rights reserved.

Impact of polymer formulations on neointimal proliferation after zotarolimus-eluting stent with different polymers: insights from the RESOLUTE trial.

PubMed

Waseda, Katsuhisa; Ako, Junya; Yamasaki, Masao; Koizumi, Tomomi; Sakurai, Ryota; Hongo, Yoichiro; Koo, Bon-Kwon; Ormiston, John; Worthley, Stephen G; Whitbourn, Robert J; Walters, Darren L; Meredith, Ian T; Fitzgerald, Peter J; Honda, Yasuhiro

2011-06-01

Polymer formulation may affect the efficacy of drug-eluting stents. Resolute, Endeavor, and ZoMaxx are zotarolimus-eluting stents with different stent platforms and different polymer coatings and have been tested in clinical trials. The aim of this analysis was to compare the efficacy of zotarolimus-eluting stents with different polymers. Data were obtained from the first-in man trial or first randomized trials of each stent, The Clinical RESpOnse EvaLUation of the MedTronic Endeavor CR ABT-578 Eluting Coronary Stent System in De Novo Native Coronary Artery Lesions (RESOLUTE), Randomized Controlled Trial to Evaluate the Safety and Efficacy of the Medtronic AVE ABT-578 Eluting Driver Coronary Stent in De Novo Native Coronary Artery Lesions (ENDEAVOR II), and ZoMaxx I trials. Follow-up intravascular ultrasound analyses (8 to 9 months of follow-up) were possible in 353 patients (Resolute: 88, Endeavor: 98, ZoMaxx: 82, Driver: 85). Volume index (volume/stent length) was obtained for vessel, stent, lumen, peristent plaque, and neointima. Cross-sectional narrowing was defined as neointimal area divided by stent area (%). Neointima-free frame ratio was calculated as the number of frames without intravascular ultrasound-detectable neointima divided by the total number of frames within the stent. At baseline, vessel, lumen, and peristent plaque volume index were not significantly different among the 4 stent groups. At follow-up, percent neointimal obstruction was significantly lower in Resolute compared with Endeavor, ZoMaxx, and Driver (Resolute: 3.7±4.0, Endeavor: 17.5±10.1, ZoMaxx: 14.6±8.1, Driver: 29.4±17.2%; P<0.001). Greater maximum cross-sectional narrowing and higher neointima-free frame ratio, suggesting less neointimal coverage, were observed in Resolute compared with other stent groups. Multiple regression analysis confirmed that the biodurable polymer used in Resolute independently correlated with neointimal suppression among 3 zotarolimus-eluting stents. The different polymer formulations significantly affect the relative amount of neointima for zotarolimus-eluting stents. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00248079.

Orbital atherectomy as an adjunct to debulk difficult calcified lesions prior to mesenteric artery stenting.

PubMed

Manunga, Jesse M; Oderich, Gustavo S

2012-08-01

To describe a technique in which percutaneous orbital atherectomy is used to debulk heavily calcified superior mesenteric artery (SMA) occlusions as an adjunct in patients undergoing angioplasty and stenting. The technique is demonstrated in a 62-year-old woman with a replaced right hepatic artery originating from an SMA occluded by densely calcified lesions. Via a left transbrachial approach, a 7-F MPA guide catheter was used to engage the ostium of the SMA, which was crossed using a catheter and guidewire. The calcified lesion was debulked using the 2-mm Diamondback 360° orbital atherectomy system. The wire was exchanged for a 0.014-inch filter wire and 0.018-inch guidewire. Using a 2-guidewire technique, the SMA was stented with a self-expanding stent for the distal lesion that crossed side branches and a balloon-expandable stent at the ostium. A 0.014-inch guidewire was placed into the replaced hepatic artery through a cell of the self-expanding stent, followed by deployment of a small balloon-expandable stent to address the residual lesion. The use of orbital atherectomy to debulk occluded and heavily calcified SMA lesions may optimize the technical results with angioplasty and stenting.

Relay NBS Graft with the Plus Delivery System to Improve Deployment in Aortic Arch with Small Radius Curve

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

Ferro, Carlo; Rossi, Umberto G., E-mail: urossi76@hotmail.com; Seitun, Sara

The purpose of this report is to describe deployment of the Relay NBS Thoracic Stent Graft with the Plus Delivery System (Bolton Medical, Sunrise, FL) in a flexible resin arch model with a 15-mm radius curve as well as our preliminary clinical results. The Relay NBS graft with the Plus Delivery System was evaluated by way of bench testing, which was performed with stent grafts with diameters ranging from 24 to 46 mm and lengths ranging from 100 to 250 mm in flexible resin arch models with a 15-mm arch radius of curvature. The deployment sequence was analyzed. The Relaymore » NBS graft with the Plus Delivery System was deployed in two patients, respectively, having a 6.5-cm penetrating aortic ulcer of the proximal third of the descending thoracic aorta and a DeBakey type-I aortic dissection with chronic false lumen dilatation after surgery due to an entry site at the distal thoracic aorta. Bench tests showed proper conformation and apposition of the Relay NBS graft with the Plus Delivery System in the flexible resin model. This stent graft was deployed successfully into the two patients with a correct orientation of the first stent and without early or late complications. The Relay NBS graft with the Plus Delivery System ensures an optimal conformation and apposition of the first stent in the aortic arch with a small radius of curvature.« less

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.

Interaction of intraluminal tissue and coronary sinus lead stabilized with stent placement.

PubMed

Balázs, Tibor; Merkely, Béla; Bognár, Eszter; Zima, Endre

2013-04-01

The aim of our investigation was to examine the intraluminal interaction of the vascular tissue and the implanted coronary sinus lead stabilized with stent on two human hearts removed before transplantation. The coronary sinus lumen was sectioned under operational microscope and opened carefully. The leads and stents were found separately positioned beside each other completely covered by an intact intimal tissue layer. No sign of occluding proliferative tissue was observed. Stent fixation technique and extraction of the CS lead in our cases did not have any particular damaging effect on the vascular system. © 2012 Wiley Periodicals, Inc.

Direct implantation of rapamycin-eluting stents with bioresorbable drug carrier technology utilising the Svelte coronary stent-on-a-wire: the DIRECT II study.

PubMed

Verheye, Stefan; Khattab, Ahmed A; Carrie, Didier; Stella, Pieter; Slagboom, Ton; Bartunek, Jozef; Onuma, Yoshinobu; Serruys, Patrick W

2016-08-05

Our aim was to demonstrate the safety and efficacy of the Svelte sirolimus-eluting coronary stent-on-a-wire Integrated Delivery System (IDS) with bioresorbable drug coating compared to the Resolute Integrity zotarolimus-eluting stent with durable polymer in patients with de novo coronary artery lesions. Direct stenting, particularly in conjunction with transradial intervention (TRI), has been associated with reduced bleeding complications, procedure time, radiation exposure and contrast administration compared to conventional stenting with wiring and predilatation. The low-profile Svelte IDS is designed to facilitate TRI and direct stenting, reducing the number of procedural steps, time and cost associated with coronary stenting. DIRECT II was a prospective, multicentre trial which enrolled 159 patients to establish non-inferiority of the Svelte IDS versus Resolute Integrity using a 2:1 randomisation. The primary endpoint was angiographic in-stent late lumen loss (LLL) at six months. Target vessel failure (TVF), as well as secondary clinical endpoints, will be assessed annually up to five years. At six months, in-stent LLL was 0.09±0.31 mm in the Svelte IDS group compared to 0.13±0.27 mm in the Resolute Integrity group (p<0.001 for non-inferiority). TVF at one year was similar across the Svelte IDS and Resolute Integrity groups (6.5% vs. 9.8%, respectively). DIRECT II demonstrated the non-inferiority of the Svelte IDS to Resolute Integrity with respect to in-stent LLL at six months. Clinical outcomes at one year were comparable between the two groups.

Implantability, Complications, and Follow-Up After Transjugular Intrahepatic Portosystemic Stent-Shunt Creation With the 6F Self-Expanding Sinus-SuperFlex-Visual Stent.

PubMed

Spira, Daniel; Wiskirchen, Jakub; Lauer, Ulrich; Ketelsen, Dominik; Nikolaou, Konstantin; Wiesinger, Benjamin

2016-07-01

The transjugular intrahepatic portosystemic stent-shunt (TIPSS) builds a shortcut between the portal vein and a liver vein, and represents a sophisticated alternative to open surgery in the management of portal hypertension or its complications. To describe clinical experiences with a low-profile nitinol stent system in TIPSS creation, and to assess primary and long-term success. Twenty-six patients (5 females, 21 males; mean age 54.6 years) were treated using a low-profile 6F self-expanding sinus-SuperFlex-Visual stent system. The indication for TIPSS creation was refractory bleeding in 9 of the 26 patients, refractory ascites in 18 patients, and acute thrombosis of the portal vein confluence in one patient. Portosystemic pressure gradients before and after TIPSS, periprocedural and long-term complications, and the time to orthotopic liver transplantation (OLT) or death were recorded. The portosystemic pressure gradient was significantly reduced, from 20.9 ± 6.3 mmHg before to 8.2 ± 2.3 mmHg after TIPSS creation (P < 0.001). Procedure-related complications included acute tract occlusion (n = 2), liver hematoma (n = 1), hepatic encephalopathy (n = 1), and cardiac failure (n = 1). Three of the 26 patients had late-onset TIPSS occlusion (at 12, 12, and 39 months after TIPSS creation). Three patients died within one week after the procedure due to their poor general condition (multiorgan failure, acute respiratory distress syndrome, necrotizing pancreatitis, and aspiration pneumonia). Another four patients succumbed to their underlying advanced liver disease within one year after TIPSS insertion. Seven patients underwent OLT at a mean time of 9.4 months after TIPSS creation. The sinus-SuperFlex-Visual stent system can be safely deployed as a TIPSS device. The pressure gradient reduction was clinically sufficient to treat the patients' symptoms, and periprocedural complications were due to the TIPSS procedure per se rather than to the particular stent system employed in this study.

Ultra-low profile Ovation device: is it the definitive solution for EVAR?

PubMed

de Donato, G; Setacci, F; Sirignano, P; Galzerano, G; Borrelli, M P; di Marzo, L; Setacci, C

2014-02-01

When Juan Parodi implanted an endograft in a human body for the first time on September 7, 1990 in Buenos Aires, Argentina, the delivery system of the handmade device was primitive, extremely rigid, and had a bulky profile of 27 French (F). Since then, stent-graft technology has evolved rapidly, limitations of earlier-generation devices have been overtaken, and endovascular aneurysm repair (EVAR) eligibility has increased enormously. Nevertheless (still) challenging aortoiliac anatomy such as short and complex proximal aortic neck seal zones and narrow access vessels are responsible for EVAR ineligibility in up to 50% of cases. The Ovation Prime abdominal stent-graft system (TriVascular, Inc., Santa Rosa, CA, USA) is a trimodular device designed with the aortic body delivered via a flexible, hydrophilic-coated, ultra-low profile catheter (14-F outer diameter - OD). The aortic body is provided with a suprarenal nitinol stent with anchors that provide active fixation, while a network of rings and channels that are inflated with a low-viscosity radiopaque polymer during stent-graft deployment, provides effective sealing. The previous EVAR technology aimed to both anchor and seal using stents combined with fabric, with neither optimized for their roles and each forced to compete for the same space within their delivery catheters, which inevitably led to larger profile of the delivery system. The technical revolution of the Ovation endograft includes the idea to truly uncouple the stages of stent-graft fixation and seal during the procedure. In the Ovation endograft platform, stent and fabric are not competing the same space within the delivery system and an ultra-low profile delivery can be achieved without compromise. With such a low-profile delivery catheter, approximately 90% of men and 70% of women with abdominal aortic aneurysm have access vessel diameters considered fit for endovascular repair. The aim of this review paper was to analyze the main properties of Ovation endograft, to emphasize the advantage of the ultra-low profile device, and to sum up current literature.

Curve micromachining on the edges of nitinol biliary stent by ultrashort pulses laser

NASA Astrophysics Data System (ADS)

Hung, Chia-Hung; Chang, Fuh-Yu

2017-05-01

In this study, a curve micromaching process on the edges of nitinol biliary stent was proposed by a femtosecond laser system with a galvano-mirror scanner. Furthermore, the outer diameter of nitinol tube was 5.116 mm, its inner diameter was 4.648 mm, and its length was 100 mm. The initial fabricated results of nitinol biliary stent represented that the edges of nitinol biliary stent were steep and squared by femtosecond laser. However, the results also indicated that if the laser movement path was precisely programmed by utilizing the unique characteristic of Gaussian beam of femtosecond laser with aligning the edges of stent, the radius of edges enhanced significantly from 9 μm to 42.5 μm. As a result, the edges of nitinol biliary stent can be successfully fabricated from squared edges to rounded-shaped edges with precise dimension, clean surface morphology, and minimal heat-affected zone remained. Hence, the nitinol biliary stent, after femtosecond laser micromachining, would not need any further post-process to remove heat-affected zone and the squared edges.

Intracoronary stent implantation: new approach using a monorail system and new large-lumen 7F catheters from the brachial route.

PubMed

Jenny, D B; Robert, G P; Fajadet, J C; Cassagneau, B G; Marco, J

1992-04-01

In this brief report we describe a case of successful multivessel PTCA with intracoronary stent implantation using a new large-lumen 7F catheter from the left brachial approach. The application of this technique should be considered for intravascular stent implantation when anticoagulation ideally should not be interrupted or in anatomical situations limiting femoral vascular access.

A break-even price calculation for the use of sirolimus-eluting stents in angioplasty.

PubMed

Galanaud, Jean-Philippe; Delavennat, Juliette; Durand-Zaleski, Isabelle

2003-03-01

One of the major complications of angioplasty is the early occurrence of restenosis requiring a repeat procedure. When bare-metal stents are used, clinical restenosis results in a repeat procedure in 10% to 15% of cases. Based on the results of an international, randomized clinical trial, the use of sirolimus-eluting stents reduces this risk. The aims of this study were to calculate the theoretical break-even price for sirolimus-eluting stents in France, the Netherlands, and the United States, and to determine the additional health care cost per patient. The break-even price was calculated by adding the savings resulting from a 15% decrease in the rate of clinical restenosis to the price of bare-metal stents. Costs were computed from the viewpoint of the health care system, exclusive of other societal costs. The break-even prices were 1291 Euro to 1489 Euro in France, 2028 Euro in the Netherlands, and 2708 Euroin the United States (1.00 Euro = 1.00 US dollar in purchasing power parity). These results indicate that the commercial price of sirolimuseluting stents will increase hospital spending for patients undergoing angioplasty by 17% to 55% per patient. This additional cost to the health care system should be discussed in view of possible productivity savings and improved quality of life for patients.

Outcome and management of pacemaker-induced superior vena cava syndrome.

PubMed

Fu, Hai-Xia; Huang, Xin-Miao; Zhong, Li; Osborn, Michael J; Bjarnason, Haraldur; Mulpuru, Siva; Zhao, Xian-Xian; Friedman, Paul A; Cha, Yong-Mei

2014-11-01

We aimed to determine the long-term outcomes of percutaneous lead extraction and stent placement in patients with pacemaker-induced superior vena cava (SVC) syndrome. The study retrospectively screened patients who underwent lead extraction followed by central vein stent implantation at Mayo Clinic (Rochester, MN, USA), from January 2005 to December 2012, to identify the patients with pacemaker-induced SVC syndrome. Demographic, clinical, and follow-up characteristics of those patients were collected from electronic medical records. Six cases were identified. The mean (standard deviation) age was 56 (15) years (male, 67%). All patients had permanent dual-chamber pacemakers, with a mean 11-year history of pacemaker placement. The entire device system was explanted in five patients; one patient had a 21-year-old pacemaker lead that could not be removed. Eight stents were implanted in six patients: five patients had one stent, one patient had three. A new pacemaker system was reimplanted through the stented vein in five patients. Technical success was achieved in all patients, without any complication. Symptoms rapidly resolved in all patients after stent deployment. The mean follow-up duration was 48 months (range, 10-100 months). Three patients remained symptom free. Reintervention with percutaneous balloon venoplasty was successful in three patients with symptom recurrence. Percutaneous stent implantation after lead removal followed by reimplantation of leads is a feasible alternative therapy for pacemaker-induced SVC syndrome, although some cases may require repeat intervention. ©2014 Wiley Periodicals, Inc.

Systemic rapamycin to prevent in-stent stenosis in peripheral pulmonary arterial disease: early clinical experience.

PubMed

Hallbergson, Anna; Esch, Jesse J; Tran, Trang X; Lock, James E; Marshall, Audrey C

2016-10-01

We have taken a novel approach using oral rapamycin - sirolimus - as a medical adjunct to percutaneous therapy in patients with in-stent stenosis and high risk of right ventricular failure. Peripheral pulmonary artery stenosis can result in right ventricular hypertension, dysfunction, and death. Percutaneous pulmonary artery angioplasty and stent placement acutely relieve obstructions, but patients frequently require re-interventions due to re-stenosis. In patients with tetralogy of Fallot or arteriopathy, the problem of in-stent stenosis contributes to the rapidly recurrent disease. Rapamycin was administered to 10 patients (1.5-18 years) with peripheral pulmonary stenosis and in-stent stenosis and either right ventricular hypertension, pulmonary blood flow maldistribution, or segmental pulmonary hypertension. Treatment was initiated around the time of catheterisation and continued for 1-3 months. Potential side-effects were monitored by clinical review and blood tests. Target serum rapamycin level (6-10 ng/ml) was accomplished in all patients; eight of the nine patients who returned for clinically indicated catheterisations demonstrated reduction in in-stent stenosis, and eight of the 10 patients experienced no significant side-effects. Among all, one patient developed diarrhoea requiring drug discontinuation, and one patient experienced gastrointestinal bleeding while on therapy that was likely due to an indwelling feeding tube and this patient tolerated rapamycin well following tube removal. Our initial clinical experience supports that patients with peripheral pulmonary artery stenosis can be safely treated with rapamycin. Systemic rapamycin may provide a novel medical approach to reduce in-stent stenosis.

Endoscopic and Photodynamic Therapy of Cholangiocarcinoma

PubMed Central

Meier, Benjamin; Caca, Karel

2016-01-01

Background Most patients with cholangiocarcinoma (CCA) have unresectable disease. Endoscopic bile duct drainage is one of the major objectives of palliation of obstructive jaundice. Methods/Results Stent implantation using endoscopic retrograde cholangiography is considered to be the standard technique. Unilateral versus bilateral stenting is associated with different advantages and disadvantages; however, a standard approach is still not defined. As there are various kinds of stents, there is an ongoing discussion on which stent to use in which situation. Palliation of obstructive jaundice can be augmented through the use of photodynamic therapy (PDT). Studies have shown a prolonged survival for the combinations of PDT and different stent applications as well as combinations of PDT and additional systemic chemotherapy. Conclusion More well-designed studies are needed to better evaluate and standardize endoscopic treatment of unresectable CCA. PMID:28229075

Endoscopic and Photodynamic Therapy of Cholangiocarcinoma.

PubMed

Meier, Benjamin; Caca, Karel

2016-12-01

Most patients with cholangiocarcinoma (CCA) have unresectable disease. Endoscopic bile duct drainage is one of the major objectives of palliation of obstructive jaundice. Stent implantation using endoscopic retrograde cholangiography is considered to be the standard technique. Unilateral versus bilateral stenting is associated with different advantages and disadvantages; however, a standard approach is still not defined. As there are various kinds of stents, there is an ongoing discussion on which stent to use in which situation. Palliation of obstructive jaundice can be augmented through the use of photodynamic therapy (PDT). Studies have shown a prolonged survival for the combinations of PDT and different stent applications as well as combinations of PDT and additional systemic chemotherapy. More well-designed studies are needed to better evaluate and standardize endoscopic treatment of unresectable CCA.

When is carotid angioplasty and stenting the cost-effective alternative for revascularization of symptomatic carotid stenosis? A Canadian health system perspective.

PubMed

Almekhlafi, M A; Hill, M D; Wiebe, S; Goyal, M; Yavin, D; Wong, J H; Clement, F M

2014-02-01

Carotid revascularization procedures can be complicated by stroke. Additional disability adds to the already high costs of the procedure. To weigh the cost and benefit, we estimated the cost-utility of carotid angioplasty and stenting compared with carotid endarterectomy among patients with symptomatic carotid stenosis, with special emphasis on scenario analyses that would yield carotid angioplasty and stenting as the cost-effective alternative relative to carotid endarterectomy. A cost-utility analysis from the perspective of the health system payer was performed by using a Markov analytic model. Clinical estimates were based on a meta-analysis. The procedural costs were derived from a microcosting data base. The costs for hospitalization and rehabilitation of patients with stroke were based on a Canadian multicenter study. Utilities were based on a randomized controlled trial. In the base case analysis, carotid angioplasty and stenting were more expensive (incremental cost of $6107) and had a lower utility (-0.12 quality-adjusted life years) than carotid endarterectomy. The results are sensitive to changes in the risk of clinical events and the relative risk of death and stroke. Carotid angioplasty and stenting were more economically attractive among high-risk surgical patients. For carotid angioplasty and stenting to become the preferred option, their costs would need to fall from more than $7300 to $4350 or less and the risks of the periprocedural and annual minor strokes would have to be equivalent to that of carotid endarterectomy. In the base case analysis, carotid angioplasty and stenting were associated with higher costs and lower utility compared with carotid endarterectomy for patients with symptomatic carotid stenosis. Carotid angioplasty and stenting were cost-effective for patients with high surgical risk.

FiberNet--a new embolic protection device for carotid artery stenting.

PubMed

Bauer, C; Franke, J; Bertog, S C; Woerner, V; Ghasemzadeh-Asl, S; Sievert, H

2014-05-01

Though distal filter protection during carotid stenting reduces the risk of cerebrovascular events, periprocedural stroke remains a risk despite their broad usage. This observation may be related to the pore size of common filters. The FiberNet distal filter system is unique by its very small pore size (40 µm) as well as its low profile and flexibility. Little data is available regarding the clinical performance and safety of this device. The aim was the evaluation of the safety of the FiberNet embolic protection system during carotid artery stenting. All consecutive patients treated with carotid stenting at our institution using the FiberNet device were systematically followed. Primary endpoint was the rate of all death and stroke within 30 days of the procedure. Carotid artery stenting using the FiberNet embolic protection system was performed in 54 patients. The procedure was technical successful in all patients. Three patients (5.5%) had a TIA. Amauosis fugax occurred in two patients (3.7%). One patient (1.9%) had a minor stroke with hemiparesis of the left arm and face which resolved completely within 48 hr after the procedure. No patient died or suffered a major stroke. The safety and feasibility of the FiberNet distal protection system appears to be at least equivalent to that reported in studies using conventional distal filter protection. Copyright © 2013 Wiley Periodicals, Inc.

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

Lanciego, Carlos; Miguel, Silvia De; Padilla, Manuel

The purpose of this study was to evaluate, in a prospective, single-center study, the effectiveness of Song's polyurethane stents, modified 'in-house,' in the percutaneous management of epiphora. Patients (n = 170; age range 18-83, mean = 64; 50 male, 120 female) with severe epiphora had the modified stents inserted (183 eyes/195 stents) to treat unilateral/bilateral and complete/partial obstruction of the nasolacrimal system. The etiology of the obstruction was idiopathic in 119 cases (61%) and chronic dacryocystitis in 76 (39%). The set designed by Song was used in all patients but modified by us such that the extreme end is cone-shaped.more » The original technique was slightly modified by us and the procedure was conducted on an outpatient basis. The initial technical success rate of stent placement was 97%. Resolution of epiphora was complete in 180 eyes and partial in 3. On follow-up (mean = 18 months; range: 2 days to 24 months), 165 of 195 stents (85%) remained patent. Primary patency rates at follow-up were 86%, 84%, 84%, and 79% in the first 6 months, second and third 6 months, and the present (24 months), respectively. Stents became obstructed in 30 patients, but all but 2 were easily withdrawn and 20 of these patients remained asymptomatic for a mean of 14 months (secondary patency of 67%). Following stent removal, the withdrawn stent was replaced with a new stent in the same intervention on 14 occasions. In another six cases, patency was re-established without the need of a second stent. The procedure is simple and safe, both in stent insertion as well as in mechanical de-blocking and withdrawal when occluded. Success was >80 % in the short term (1-year follow-up). Stenting failure does not preclude other treatment because with the modification that we had introduced, the extreme end of the stent becomes more accessible to mechanical de-blocking, withdrawal, and relocation. The levels of primary and secondary patencies are promising and warrant more extensive investigation.« less

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 tissue is less likely to occur in areas of established scar than in areas of acute inflammation. In circumstances in which it is essential that a stent remain only temporarily, an expandable stent should not be inserted in favor of a silicone stent, which can be removed. In the future, expandable stents may have silicone coverings or may be constructed of materials that facilitate removal. Until that time, expandable stents should be considered permanent and nonremovable. Subtle differences exist among the available stents. Standard is low-profile expandable construction from wire mesh. A relatively minor difference is the slightly wider expansibility of the Gianturco stent, a quality that makes it the best suited of the three stents for lesions that involve tracheomalacia. Perhaps the only major difference between the Wallstent and the Gianturco and Palmaz stents is its better ability to conform to tortuous lesions. In an acutely angled stricture, a Wallstent offers a better opportunity for successful placement than other stents. The filamentous meshwork of the Wallstent allows it to bend and conform better to distorted airways. The Gianturco and Palmaz stents have little longitudinal elasticity, which makes them less effective in a tortuous or highly angulated airway stenosis. Expandable stents have demonstrated their efficacy and exposed their limitations in the treatment of airway stenoses. Refinements in design should help to lessen specific disadvantages and problems. Covered expandable stents, a realistic prospect, have specific advantages over standard expandable stents; they will be removable and prevent tumor ingrowth. Current investigative work with such prostheses for the vascular system may provide the foundation for their investigative use in the airway. In essence, two categories of expandable stents are evolving, covered and uncovered, each having unique features adaptable to the specific clinical needs.

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.

Improvement in conformability of the latest generation of thoracic stent grafts.

PubMed

Canaud, Ludovic; Cathala, Philipe; Joyeux, Frédéric; Branchereau, Pascal; Marty-Ané, Charles; Alric, Pierre

2013-04-01

Poor aortic arch apposition increases the risk of technical failure after thoracic endovascular repair. The aim of this study was to assess the conformability of the latest generation of thoracic stent grafts in relation to the degree of device oversizing and aortic arch angulation. A benchtop pulsatile flow model was designed to test stent graft anchorage in a 2-cm-long proximal landing zone at varying landing zone angles (from 140° down to 70°) and stent graft oversizing (12%-28%). The experiments were performed using 10 human thoracic cadaveric aortas and four stent grafts: C-TAG, Zenith TX2 Pro-Form, Valiant Captivia, and Relay. Device-wall apposition was measured as a function of landing zone angulation and oversizing during static and dynamic (60 pulses/min, 300/150 mm Hg) tests. The Valiant stent graft remained apposed to the aortic wall at each increment of neck angulation and device oversizing. Lack of apposition of the proximal anchorage segment was observed with the C-TAG above 120° landing zone angulation (1-2 mm) and with the Relay above 110° landing zone angulation (1-4 mm). Lack of "body" apposition (1-4 mm) was first observed with the Zenith Pro-Form stent graft above 110° angulation (P = .001). When the device was not apposed to the aortic wall, an increase in stent graft oversizing significantly (P = .01) decreased device-wall apposition. The requirement for close conformability has influenced the design of next-generation devices. Manufacturers have modified devices and/or their deployment system to specifically address this problem. When compared with the results of our previous experimental test, this study demonstrates that these alterations have resulted in a marked improvement in the performance of commercially available stent graft systems. Copyright © 2013 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

Electro and Magneto-Electropolished Surface Micro-Patterning on Binary and Ternary Nitinol

PubMed Central

Munroe, Norman; McGoron, Anthony

2012-01-01

In this study, an Atomic Force Microscopy (AFM) roughness analysis was performed on non-commercial Nitinol alloys with Electropolished (EP) and Magneto-Electropolished (MEP) surface treatments and commercially available stents by measuring Root-Mean-Square (RMS), Average Roughness (Ra), and Surface Area (SA) values at various dimensional areas on the alloy surfaces, ranging from (800 × 800 nm) to (115 × 115μm), and (800 × 800 nm) to (40 × 40 μm) on the commercial stents. Results showed that NiTi-Ta 10 wt% with an EP surface treatment yielded the highest overall roughness, while the NiTi-Cu 10 wt% alloy had the lowest roughness when analyzed over (115 × 115 μm). Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analysis revealed unique surface morphologies for surface treated alloys, as well as an aggregation of ternary elements Cr and Cu at grain boundaries in MEP and EP surface treated alloys, and non-surface treated alloys. Such surface micro-patterning on ternary Nitinol alloys could increase cellular adhesion and accelerate surface endothelialization of endovascular stents, thus reducing the likelihood of in-stent restenosis and provide insight into hemodynamic flow regimes and the corrosion behavior of an implantable device influenced from such surface micro-patterns. PMID:22754200

Wall stress reduction in abdominal aortic aneurysms as a result of polymeric endoaortic paving.

PubMed

Ashton, John H; Ayyalasomayajula, Avinash; Simon, Bruce R; Vande Geest, Jonathan P

2011-06-01

Polymeric endoaortic paving (PEAP) may improve endovascular repair of abdominal aortic aneurysms (AAA) since it has the potential to treat patients with complex AAA geometries while reducing the incidence of migration and endoleak. Polycaprolactone (PCL)/polyurethane (PU) blends are proposed as PEAP materials due to their range of mechanical properties, thermoformability, and resistance to biodegradation. In this study, the reduction in AAA wall stress that can be achieved using PEAP was estimated and compared to that resulting from stent-grafts. This was accomplished by mechanically modeling the anisotropic response of PCL/PU blends and implementing these results into finite element model (FEM) simulations. We found that at the maximum diameter of the AAA, the 50/50 and 10/90 PCL/PU blends reduced wall stress by 99 and 98%, respectively, while a stent-graft reduced wall stress by 99%. Our results also show that wall stress reduction increases with increasing PEAP thickness and PCL content in the blend ratio. These results indicate that PEAP can reduce AAA wall stress as effectively as a stent-graft. As such, we propose that PEAP may provide an improved treatment alternative for AAA, since many of the limitations of stent-grafts have the potential to be solved using this approach.

Ultrathin, bioresorbable polymer sirolimus-eluting stents versus thin, durable polymer everolimus-eluting stents in patients undergoing coronary revascularisation (BIOFLOW V): a randomised trial.

PubMed

Kandzari, David E; Mauri, Laura; Koolen, Jacques J; Massaro, Joseph M; Doros, Gheorghe; Garcia-Garcia, Hector M; Bennett, Johan; Roguin, Ariel; Gharib, Elie G; Cutlip, Donald E; Waksman, Ron

2017-10-21

The development of coronary drug-eluting stents has included use of new metal alloys, changes in stent architecture, and use of bioresorbable polymers. Whether these advancements improve clinical safety and efficacy has not been shown in previous randomised trials. We aimed to examine the clinical outcomes of a bioresorbable polymer sirolimus-eluting stent compared with a durable polymer everolimus-eluting stent in a broad patient population undergoing percutaneous coronary intervention. BIOFLOW V was an international, randomised trial done in patients undergoing elective and urgent percutaneous coronary intervention in 90 hospitals in 13 countries (Australia, Belgium, Canada, Denmark, Germany, Hungary, Israel, the Netherlands, New Zealand, South Korea, Spain, Switzerland, and the USA). Eligible patients were those aged 18 years or older with ischaemic heart disease undergoing planned stent implantation in de-novo, native coronary lesions. Patients were randomly assigned (2:1) to either an ultrathin strut (60 μm) bioresorbable polymer sirolimus-eluting stent or to a durable polymer everolimus-eluting stent. Randomisation was via a central web-based data capture system (mixed blocks of 3 and 6), and stratified by study site. The primary endpoint was 12-month target lesion failure. The primary non-inferiority comparison combined these data from two additional randomised trials of bioresorbable polymer sirolimus-eluting stent and durable polymer everolimus-eluting stent with Bayesian methods. Analysis was by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT02389946. Between May 8, 2015, and March 31, 2016, 4772 patients were recruited into the study. 1334 patients met inclusion criteria and were randomly assigned to treatment with bioresorbable polymer sirolimus-eluting stents (n=884) or durable polymer everolimus-eluting stents (n=450). 52 (6%) of 883 patients in the bioresorbable polymer sirolimus-eluting stent group and 41 (10%) of 427 patients in the durable polymer everolimus-eluting stent group met the 12-month primary endpoint of target lesion failure (95% CI -6·84 to -0·29, p=0·0399), with differences in target vessel myocardial infarction (39 [5%] of 831 patients vs 35 [8%] of 424 patients, p=0·0155). The posterior probability that the bioresorbable polymer sirolimus-eluting stent is non-inferior to the durable polymer everolimus-eluting stent was 100% (Bayesian analysis, difference in target lesion failure frequency -2·6% [95% credible interval -5·5 to 0·1], non-inferiority margin 3·85%, n=2208). The outperformance of the ultrathin, bioresorbable polymer sirolimus-eluting stent over the durable polymer everolimus-eluting stent in a complex patient population undergoing percutaneous coronary intervention suggests a new direction in improving next generation drug-eluting stent technology. BIOTRONIK. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of the Anti-migration Effect of Barbed Prostatic Stents: In Vitro Study in Urethra-mimicking Bovine Pericardium Phantoms

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

Na, Han Kyu, E-mail: hankyu1324@empas.com; Song, Ho-Young, E-mail: hysong@amc.seoul.kr; Kim, Jin Hyoung, E-mail: m1fenew@hanmail.net

2013-02-15

This study was designed to compare the migration rates of covered stents with eight, four, and zero barbs in urethra-mimicking bovine pericardium models. Three types of polytetrafluoroethylene-covered retrievable self-expandable prostatic stents, with eight, four, and zero barbs, were tested in bovine pericardium models, consisting of normal saline-filled acrylic containers with tubes at both ends and a replica of the human urethra. The barbs were 2 mm in length and projected 60 Degree-Sign toward the urinary bladder. The anti-migration force (AMF) and resistance force against stent removal (RFSR) were measured by an automatic push-pull gauge system at a fixed rate (2more » mm/s). Significant differences in AMF among the three stent types were detected (P < 0.001). Median AMF was far greater for eight-barbed than for four-barbed stents (11.96 vs. 7.55 N, P = 0.003). For stent removal, the difference between 4- and 8-barbed stents were not significant in median static (5.54 vs. 6.08 N, P = 0.15) or sliding (prostatic urethra, 5.32 vs. 5.59 N, P = 0.65; membranous urethra, 7.78 vs. 8.57 N, P = 0.364) RFSR. No perforations or scratched traces were observed during removal of these stents. The inclusion of eight barbs projecting 60 Degree-Sign toward the urinary bladder were not only effective against stent migration in this model but suggests that these stents may be suitable for the treatment of prostatic urethral strictures without severely irritating the tissue. However, whether these results translate into living urethral tissue is unclear, necessitating further studies.« less

Rationale and design of the Patient Related OuTcomes with Endeavor versus Cypher stenting Trial (PROTECT): randomized controlled trial comparing the incidence of stent thrombosis and clinical events after sirolimus or zotarolimus drug-eluting stent implantation.

PubMed

Camenzind, Edoardo; Wijns, William; Mauri, Laura; Boersma, Eric; Parikh, Keyur; Kurowski, Volkhard; Gao, Runlin; Bode, Christoph; Greenwood, John P; Gershlick, Anthony; O'Neill, William; Serruys, Patrick W; Jorissen, Brenda; Steg, P Gabriel

2009-12-01

Drug-eluting stents (DES) reduce restenosis rates compared to bare-metal stents. Most trials using DES enrolled selected patient and lesion subtypes, and primary endpoint focused on angiographic metrics or relatively short-term outcomes. When DES are used in broader types of lesions and patients, important differences may emerge in long-term outcomes between stent types, particularly the incidence of late stent thrombosis. PROTECT is a randomized, open-label trial comparing the long-term safety of the zotarolimus-eluting stent and the sirolimus-eluting stent. The trial has enrolled 8,800 patients representative of those seen in routine clinical practice, undergoing elective, unplanned, or emergency procedures in native coronary arteries in 196 centers in 36 countries. Indications for the procedure and selection of target vessel and lesion characteristics were at the operator's discretion. Procedures could be staged, but no more than 4 target lesions could be treated per patient. Duration of dual antiplatelet therapy was prespecified to achieve similar lengths of treatment in both study arms. The shortest predefined duration was 3 months, as per the manufacturer's instructions. The primary outcome measure is the composite rate of definite and probable stent thrombosis at 3 years, centrally adjudicated using Academic Research Consortium definitions. The main secondary end points are 3-year all-cause mortality, cardiac death, large nonfatal myocardial infarction, and all myocardial infarctions. This large, international, randomized, controlled trial will provide important information on comparative rates of stent thrombosis between 2 different DES systems and safety as assessed by patient-relevant long-term clinical outcomes.

A randomized controlled trial of a middle meatal silastic stent for reducing adhesions and middle turbinate lateralization following endoscopic sinus surgery.

PubMed

Chan, Chun L; Elmiyeh, Behrad; Woods, Charmaine; Ullah, Shahid; Gunawardena, Indunil; Carney, A Simon; Ooi, Eng H

2015-06-01

Endoscopic sinus surgery (ESS) is indicated for patients with recalcitrant chronic rhinosinusitis symptoms. However, surgical revision can be required because of adhesion formation and middle turbinate lateralization. We investigate the efficacy of a middle meatal silastic stent in reducing these complications after ESS. Thirty-six patients were randomized to receive a silastic stent in the middle meatus unilaterally after ESS. The surgeon was blinded to the side receiving the stent until completion of the ESS. The contralateral side, with no stent, was the control side. Patients completed a 7-day, postoperative, visual analog scale symptom diary and were blinded to the stent side until its removal at the first postoperative visit. Patients were followed up after 2, 8, and 24 weeks. Endoscopic video of the sinus cavities were recorded at all visits and 2 blinded, independent ear/nose/throat (ENT) surgeons assessed the videos using a modified Lund-Kennedy scoring system. Thirty-five of 36 patients completed 6-months' follow-up. Middle turbinate lateralization was observed in 13 sides without a stent vs 1 side with a stent. There was a significant reduction in adhesions at weeks 2 and 8 (p < 0.001) and crusting (p < 0.01) in the stent side compared to control. Video scores at 6 months after surgery for stent and control sides remained unchanged from the 8-week visit. There was no difference between sides for symptom scores, edema, or nasal discharge. Middle meatal silastic stents are well tolerated by patients and effective in reducing middle turbinate lateralization, adhesions, and crusting postoperatively in ESS. © 2015 ARS-AAOA, LLC.

Numerical analysis of urine flow through the side holes of a double J stent in a ureteral stenosis.

PubMed

Kim, Hyoung-Ho; Choi, Young Ho; Lee, Seung Bae; Baba, Yasutaka; Kim, Kyung-Wuk; Suh, Sang-Ho

2017-07-20

Ureteral stenosis presents with a narrowing in the ureter, due to an intrinsic or extrinsic ureteral disease, such as ureter cancer or retroperitoneal fibrosis. The placement of a double J stent in the upper urinary system is one of the most common treatments of ureteral stenosis, along with the insertion of a percutaneous nephrostomy tube into the renal pelvis. The effect that the side holes in a double J stent have on urine flow has been evaluated in a few studies using straight ureter models. In this study, urine flow through a double J stent's side holes was analyzed in curved ureter models, which were based on human anatomy. In ureteral stenosis, especially in severe ureteral stenosis, a stent with side holes had a positive effect on the luminal and total flow rates, compared with the rates for a stent without side holes. The more side holes a stent has, the greater the luminal and total flow rates. However, the angular positions of the side holes did not affect flow rate. In conclusion, the side holes in a double J stent had a positive effect on ureteral stenosis, and the effect became greater as the ureteral stenosis became more severe.

Monitoring the Wall Mechanics During Stent Deployment in a Vessel

PubMed Central

Steinert, Brian D.; Zhao, Shijia; Gu, Linxia

2012-01-01

Clinical trials have reported different restenosis rates for various stent designs1. It is speculated that stent-induced strain concentrations on the arterial wall lead to tissue injury, which initiates restenosis2-7. This hypothesis needs further investigations including better quantifications of non-uniform strain distribution on the artery following stent implantation. A non-contact surface strain measurement method for the stented artery is presented in this work. ARAMIS stereo optical surface strain measurement system uses two optical high speed cameras to capture the motion of each reference point, and resolve three dimensional strains over the deforming surface8,9. As a mesh stent is deployed into a latex vessel with a random contrasting pattern sprayed or drawn on its outer surface, the surface strain is recorded at every instant of the deformation. The calculated strain distributions can then be used to understand the local lesion response, validate the computational models, and formulate hypotheses for further in vivo study. PMID:22588353

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

PubMed

Upendra, K; Sanjeev, B

2012-02-01

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

Investigation of corrosion behavior of biodegradable magnesium alloys using an online-micro-flow capillary flow injection inductively coupled plasma mass spectrometry setup with electrochemical control

NASA Astrophysics Data System (ADS)

Ulrich, A.; Ott, N.; Tournier-Fillon, A.; Homazava, N.; Schmutz, P.

2011-07-01

The development of biodegradable metallic materials designed for implants or medical stents is new and is one of the most interesting new fields in material science. Besides biocompatibility, a detailed understanding of corrosion mechanisms and dissolution processes is required to develop materials with tailored degradation behavior. The materials need to be sufficiently stable as long as they have to fulfill their medical task. However, subsequently they should dissolve completely in a controlled manner in terms of maximum body burden. This study focuses on the elemental and time resolved dissolution processes of a magnesium rare earth elements alloy which has been compared to pure magnesium with different impurity level. The here described investigations were performed using a novel analytical setup based on a micro-flow capillary online-coupled via a flow injection system to a plasma mass spectrometer. Differences in element-specific and time-dependent dissolution were monitored for various magnesium alloys in contact with sodium chloride or mixtures of sodium and calcium chloride as corrosive media. The dissolution behavior strongly depends on bulk matrix elements, secondary alloying elements and impurities, which are usually present even in pure magnesium.

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.

Effect of venous stenting on intracranial pressure in idiopathic intracranial hypertension.

PubMed

Matloob, Samir A; Toma, Ahmed K; Thompson, Simon D; Gan, Chee L; Robertson, Fergus; Thorne, Lewis; Watkins, Laurence D

2017-08-01

Idiopathic intracranial hypertension (IIH) is characterised by an increased intracranial pressure (ICP) in the absence of any central nervous system disease or structural abnormality and by normal CSF composition. Management becomes complicated once surgical intervention is required. Venous sinus stenosis has been suggested as a possible aetiology for IIH. Venous sinus stenting has emerged as a possible interventional option. Evidence for venous sinus stenting is based on elimination of the venous pressure gradient and clinical response. There have been no studies demonstrating the immediate effect of venous stenting on ICP. Patients with a potential or already known diagnosis of IIH were investigated according to departmental protocol. ICP monitoring was performed for 24 h. When high pressures were confirmed, CT venogram and catheter venography were performed to look for venous stenosis to demonstrate a pressure gradient. If positive, venous stenting would be performed and ICP monitoring would continue for a further 24 h after deployment of the venous stent. Ten patients underwent venous sinus stenting with concomitant ICP monitoring. Nine out of ten patients displayed an immediate reduction in their ICP that was maintained at 24 h. The average reduction in mean ICP and pulsatility was significant (p = 0.003). Six out of ten patients reported a symptomatic improvement within the first 2 weeks. Venous sinus stenting results in an immediate reduction in ICP. This physiological response to venous stenting has not previously been reported. Venous stenting could offer an alternative treatment option in correctly selected patients with IIH.

Biodegradable Magnesium Stent Treatment of Saccular Aneurysms in a Rat Model - Introduction of the Surgical Technique.

PubMed

Nevzati, Edin; Rey, Jeannine; Coluccia, Daniel; D'Alonzo, Donato; Grüter, Basil; Remonda, Luca; Fandino, Javier; Marbacher, Serge

2017-10-01

The steady progess in the armamentarium of techniques available for endovascular treatment of intracranial aneurysms requires affordable and reproducable experimental animal models to test novel embolization materials such as stents and flow diverters. The aim of the present project was to design a safe, fast, and standardized surgical technique for stent assisted embolization of saccular aneurysms in a rat animal model. Saccular aneurysms were created from an arterial graft from the descending aorta.The aneurysms were microsurgically transplanted through end-to-side anastomosis to the infrarenal abdominal aorta of a syngenic male Wistar rat weighing >500 g. Following aneurysm anastomosis, aneurysm embolization was performed using balloon expandable magnesium stents (2.5 mm x 6 mm). The stent system was retrograde introduced from the lower abdominal aorta using a modified Seldinger technique. Following a pilot series of 6 animals, a total of 67 rats were operated according to established standard operating procedures. Mean surgery time, mean anastomosis time, and mean suturing time of the artery puncture site were 167 ± 22 min, 26 ± 6 min and 11 ± 5 min, respectively. The mortality rate was 6% (n=4). The morbidity rate was 7.5% (n=5), and in-stent thrombosis was found in 4 cases (n=2 early, n=2 late in stent thrombosis). The results demonstrate the feasibility of standardized stent occlusion of saccular sidewall aneurysms in rats - with low rates of morbidity and mortality. This stent embolization procedure combines the opportunity to study novel concepts of stent or flow diverter based devices as well as the molecular aspects of healing.

Potential-based and non-potential-based cohesive zone formulations under mixed-mode separation and over-closure-Part II: Finite element applications

NASA Astrophysics Data System (ADS)

Máirtín, Éamonn Ó.; Parry, Guillaume; Beltz, Glenn E.; McGarry, J. Patrick

2014-02-01

This paper, the second of two parts, presents three novel finite element case studies to demonstrate the importance of normal-tangential coupling in cohesive zone models (CZMs) for the prediction of mixed-mode interface debonding. Specifically, four new CZMs proposed in Part I of this study are implemented, namely the potential-based MP model and the non-potential-based NP1, NP2 and SMC models. For comparison, simulations are also performed for the well established potential-based Xu-Needleman (XN) model and the non-potential-based model of van den Bosch, Schreurs and Geers (BSG model). Case study 1: Debonding and rebonding of a biological cell from a cyclically deforming silicone substrate is simulated when the mode II work of separation is higher than the mode I work of separation at the cell-substrate interface. An active formulation for the contractility and remodelling of the cell cytoskeleton is implemented. It is demonstrated that when the XN potential function is used at the cell-substrate interface repulsive normal tractions are computed, preventing rebonding of significant regions of the cell to the substrate. In contrast, the proposed MP potential function at the cell-substrate interface results in negligible repulsive normal tractions, allowing for the prediction of experimentally observed patterns of cell cytoskeletal remodelling. Case study 2: Buckling of a coating from the compressive surface of a stent is simulated. It is demonstrated that during expansion of the stent the coating is initially compressed into the stent surface, while simultaneously undergoing tangential (shear) tractions at the coating-stent interface. It is demonstrated that when either the proposed NP1 or NP2 model is implemented at the stent-coating interface mixed-mode over-closure is correctly penalised. Further expansion of the stent results in the prediction of significant buckling of the coating from the stent surface, as observed experimentally. In contrast, the BSG model does not correctly penalise mixed-mode over-closure at the stent-coating interface, significantly altering the stress state in the coating and preventing the prediction of buckling. Case study 3: Application of a displacement to the base of a bi-layered composite arch results in a symmetric sinusoidal distribution of normal and tangential traction at the arch interface. The traction defined mode mixity at the interface ranges from pure mode II at the base of the arch to pure mode I at the top of the arch. It is demonstrated that predicted debonding patterns are highly sensitive to normal-tangential coupling terms in a CZM. The NP2, XN, and BSG models exhibit a strong bias towards mode I separation at the top of the arch, while the NP1 model exhibits a bias towards mode II debonding at the base of the arch. Only the SMC model provides mode-independent behaviour in the early stages of debonding. This case study provides a practical example of the importance of the behaviour of CZMs under conditions of traction controlled mode mixity, following from the theoretical analysis presented in Part I of this study.

Late Complication after Superficial Femoral Artery (SFA) Aneurysm: Stent-graft Expulsion Outside the Skin

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

Pecoraro, Felice, E-mail: felicepecoraro@libero.it; Sabatino, Ermanno R.; Dinoto, Ettore

A 78-year-old man presented with a 7-cm aneurysm in the left superficial femoral artery, which was considered unfit and anatomically unsuitable for conventional open surgery for multiple comorbidities. The patient was treated with stent-graft [Viabhan stent-graft (WL Gore and Associates, Flagstaff, AZ)]. Two years from stent-graft implantation, the patient presented a purulent secretion and a spontaneous external expulsion through a fistulous channel. No claudication symptoms or hemorrhagic signs were present. The pus and device cultures were positive for Staphylococcus aureus sensitive to piperacillin/tazobactam. Patient management consisted of fistula drainage, systemic antibiotic therapy, and daily wound dressing. At 1-month follow-up, themore » wound was closed. To our knowledge, this is the first case of this type of stent-graft complication presenting with external expulsion.« less

Stenting in Malignant Biliary Obstruction.

PubMed

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

2015-10-01

Decompression of the biliary system in patients with malignant biliary obstruction has been widely accepted and implemented as part of the care. Despite a wealth of literature, there remains a significant amount of uncertainty as to which approach would be most appropriate in different clinical settings. This review covers stenting of the biliary system in cases of resectable or palliative malignant biliary obstruction, potential candidates for biliary drainage, technical aspects of the procedure, as well as management of biliary stent dysfunction. Furthermore, periprocedural considerations including proper mapping of the location of obstruction and the use of antibiotics are addressed. Copyright © 2015 Elsevier Inc. All rights reserved.

Risk factors for technical failure of endoscopic double self-expandable metallic stent placement by partial stent-in-stent method.

PubMed

Kawakubo, Kazumichi; Kawakami, Hiroshi; Toyokawa, Yoshihide; Otani, Koichi; Kuwatani, Masaki; Abe, Yoko; Kawahata, Shuhei; Kubo, Kimitoshi; Kubota, Yoshimasa; Sakamoto, Naoya

2015-01-01

Endoscopic double self-expandable metallic stent (SEMS) placement by the partial stent-in-stent (PSIS) method has been reported to be useful for the management of unresectable hilar malignant biliary obstruction. However, it is technically challenging, and the optimal SEMS for the procedure remains unknown. The aim of this study was to identify the risk factors for technical failure of endoscopic double SEMS placement for unresectable malignant hilar biliary obstruction (MHBO). Between December 2009 and May 2013, 50 consecutive patients with MHBO underwent endoscopic double SEMS placement by the PSIS method. We retrospectively evaluated the rate of successful double SEMS placement and identified the risk factors for technical failure. The technical success rate for double SEMS placement was 82.0% (95% confidence interval [CI]: 69.2-90.2). On univariate analysis, the rate of technical failure was high in patients with metastatic disease and unilateral placement. Multivariate analysis revealed that metastatic disease was a significant risk factor for technical failure (odds ratio: 9.63, 95% CI: 1.11-105.5). The subgroup analysis after double guidewire insertion showed that the rate of technical success was higher in the laser-cut type SEMS with a large mesh and thick delivery system than in the braided type SEMS with a small mesh and thick delivery system. Metastatic disease was a significant risk factor for technical failure of double SEMS placement for unresectable MHBO. The laser-cut type SEMS with a large mesh and thin delivery system might be preferable for the PSIS procedure. © 2014 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

Comparative effectiveness of commonly used devices for carotid artery stenting: an NCDR Analysis (National Cardiovascular Data Registry).

PubMed

Giri, Jay; Kennedy, Kevin F; Weinberg, Ido; Hawkins, Beau M; Press, Marcella Calfon; Drachman, Douglas; McCormick, Daniel J; Aronow, Herbert D; White, Christopher J; Rosenfield, Kenneth; Yeh, Robert W

2014-02-01

This study sought to characterize usage and outcomes of carotid stenting platforms. A variety of stents and embolic protection devices (EPDs) are used for carotid artery stenting. Little is known about current usage patterns and differences in outcomes with these devices. We analyzed 12,135 consecutive carotid stent procedures in the NCDR (National Cardiovascular Data Registry) CARE (Carotid Artery Revascularization and Endarterectomy) registry performed between January 1, 2007 and March 31, 2012. We compared baseline characteristics and crude and multivariable-adjusted rates of in-hospital combined death/stroke among patients treated with Acculink/Accunet (Abbott Laboratories, Abbott Park, Illinois), Xact/Emboshield (Abbott), and Precise/Angioguard (Cordis Corporation, Bridgewater, New Jersey) stent/EPD combinations. In 78.2% of cases, stents were used in conjunction with their specific, corresponding U.S. Food and Drug Administration-approved EPD. The Acculink/Accunet (n = 2,617, 21.6%), Xact/Emboshield (n = 3,507, 28.9%), and Precise/Angioguard (n = 2,696, 22.2%) stent/EPD combinations were used in 72.7% of all cases. The Protégé/SpiderFx (ev3 Endovascular Inc., Plymouth, Minnesota) (n = 453, 3.7%) and Wallstent/Filterwire (Boston Scientific, Natick, Massachusetts) (n = 213, 1.8%) devices were used in a minority of cases. In unadjusted analyses, the Precise/Angioguard system was associated with higher rates of the primary outcome than were the Acculink/Accunet (2.5% vs. 1.8%; p = 0.058) and Xact/Emboshield (2.5% vs. 1.9%; p = 0.14) systems that were not statistically different. In adjusted analyses, differences between Precise/Angioguard and Accunet/Acculink (odds ratio [OR]: 1.48, 95% confidence interval [CI]: 0.89 to 2.47; p = 0.065), Precise/Angioguard and Xact/Emboshield (OR: 1.16, 95% CI: 0.77 to 1.76; p = 0.38), and Xact/Emboshield and Accunet/Acculink (OR: 1.28, 95% CI: 0.82 to 1.97; p = 0.18) remained nonsignificant. In modern U.S. practice, the Acculink/Accunet, Xact/Emboshield, and Precise/Angioguard carotid stenting systems are used in most cases and are associated with similarly low rates of adverse events. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Impact of nitinol stent surface processing on in-vivo nickel release and biological response.

PubMed

Nagaraja, Srinidhi; Sullivan, Stacey J L; Stafford, Philip R; Lucas, Anne D; Malkin, Elon

2018-05-01

Although nitinol is widely used in percutaneous cardiovascular interventions, a causal relationship between nickel released from implanted cardiovascular devices and adverse systemic or local biological responses has not been established. The objective of this study was to investigate the relationship between nitinol surface processing, in-vivo nickel release, and biocompatibility. Nitinol stents manufactured using select surface treatments were implanted into the iliac arteries of minipigs for 6 months. Clinical chemistry profile, complete blood count, serum and urine nickel analyses were performed periodically during the implantation period. After explant, stented arteries were either digested and analyzed for local nickel concentration or fixed and sectioned for histopathological analysis of stenosis and inflammation within the artery. The results indicated that markers for liver and kidney function were not different than baseline values throughout 180 days of implantation regardless of surface finish. In addition, white blood cell, red blood cell, and platelet counts were similar to baseline values for all surface finishes. Systemic nickel concentrations in serum and urine were not significantly different between processing groups and comparable to baseline values during 180 days of implantation. However, stents with non-optimized surface finishing had significantly greater nickel levels in the surrounding artery compared to polished stents. These stents had increased stenosis with potential for local inflammation compared to polished stents. These findings demonstrate that proper polishing of nitinol surfaces can reduce in-vivo nickel release locally, which may aid in minimizing adverse inflammatory reactions and restenosis. Nitinol is a commonly used material in cardiovascular medical devices. However, relationships between nitinol surface finishing, in-vivo metal ion release, and adverse biological responses have yet to be established. We addressed this knowledge gap by implanting single and overlapped nitinol stents with different surface finishes to assess systemic impact on minipigs (i.e. serum and urine nickel levels, liver and kidney function, immune and blood count) over the 6 month implantation period. In addition, nickel levels and histopathology in stented arteries were analyzed on explant to determine relationships between surface processing and local adverse tissue reactions. The findings presented here highlight the importance of surface processing on in-vivo nickel release and subsequent impact on local biological response for nitinol implants. Published by Elsevier Ltd.

Intralacrimal migration of Masterka® stents.

PubMed

Fayet, B; Racy, E; Katowitz, W R; Katowitz, J A; Ruban, J-M; Brémond-Gignac, D

2018-03-01

Tearing and conjunctivitis in children are commonly due to lacrimal drainage system obstruction. Congenital nasolacrimal obstruction is a common pathology treated by probing with or without silicone stent insertion, depending upon the age of the child. The silicone stent is self-retaining and placed for at least one month. Masterka ® is a recent version of Monoka ® , which may lead to the same surgical complications, such as intralacrimal migration. The medical records of two patients surgically treated with the Masterka ® probe for nasolacrimal duct obstruction, who developed intralacrimal migration of the stent, were retrospectively reviewed and analyzed. A 41-month-old child and an 18-month-old child presented with disappearance of the silicone tube after 7 days and 2 years respectively. In the first case, the tube migrated completely within the lacrimal system and became externalized through the nose at 2 years, while in the second case, the Masterka ® was retrieved through a canalicular approach. In both cases, infants had no further tearing. The frequency self-retaining stent disappearance is estimated at 15%. Among these cases, intralacrimal migration is only reported in 0.5% of cases. To prevent intralacrimal migration, the surgical technique must follow a certain number of rules. Management, based on residual epiphora, is discussed. Prevention of intralacrimal migration of self-retaining stents involves a rigorous analysis of the relationship between the meatus and the fixation head at the time of placement. After lacrimal intubation, scheduled monitoring is necessary to screen for stent disappearance. Management is based on clinical findings, anterior rhinoscopy and even exploratory canaliculotomy. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Flow-independent dynamics in aneurysms: intra-aneurysm pressure measurements following complete flow cessation in internal carotid artery aneurysms.

PubMed

Qureshi, Adnan I; Qureshi, Mushtaq H; Mohindroo, Tanya; Khan, Asif A; Dingmann, Kayla; Sherr, Gregory T; Suri, M Fareed K

2014-12-01

To determine if complete flow obliteration by covered stents reduces intra-aneurysm pressures in internal carotid artery (ICA) aneurysms. A single lumen microcatheter was placed into the aneurysm sac prior to covered stent deployment in 3 patients and connected to a pressure monitoring system. The intra-aneurysm pressure was continuously monitored, and readings were recorded prior to and immediately after stent deployment and at 5-minute intervals up to 20 minutes after stent placement. Complete occlusion of flow into the aneurysms was confirmed by carotid angiography. There was no change in mean pressure within the aneurysm before and immediately after stent placement (80 mmHg) in any patient, nor was there a change in waveform of the intra-aneurysm pressure recording. The average of intra-aneurysm pressures among the 3 patients was higher (99 mmHg) at 10 and 15 minutes after stent placement. In 2 patients, the microcatheter was retracted into the parent arterial lumen; no difference in pressure was noted. Our observations suggest no change in the pressures within the aneurysm after complete flow cessation (flow-independent). These findings may assist clinicians in better understanding aneurysm hemodynamics and rupture after covered stent deployment.

First Approval of Improved Medical Device Conditional on Use-Result Survey in Japan　- Regulatory Review of Polymer-Free Drug-Coated BioFreedom Coronary Stent.

PubMed

Konishi, Akihide; Ho, Mami; Shirai, Yuko; Shirato, Haruki

2018-05-25

A prospective randomized clinical trial showed that the BioFreedom stent (Biosensors International), which is a polymer-free and carrier-free drug-coated stent, was significantly superior to a bare-metal stent (BMS) in patients at high bleeding risk who were receiving a 1-month course of dual antiplatelet therapy (DAPT). However, the stent thrombosis rate (2.01% for BioFreedom vs. 2.20% for BMS) was 4-6-fold higher than that of approved drug-eluting stents based on real-world data in Japan. Furthermore, the frequency of stent thrombosis at more than 1 month with the BioFreedom stent was slightly higher than that at less than 1 month. This result suggested that it would not be acceptable to stop DAPT universally at 1 month. Thus, the target patients for the BioFreedom stent are unspecified patients at high bleeding risk needing to continue DAPT for as long as necessary in Japan. Therefore, based on the pre- and post-marketing balance of medical devices regulations, regulatory approval was given for unspecified patients conditionally upon real-world data collection of 2,000 patients with a Use-Results Survey, instead of conducting additional pre-marketing clinical trial(s). The Use-Results Survey System is part of a strategy to expedite patients' access to innovative medical devices and to accelerate the development of medical devices.

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

Zhou, Wei-Zhong, E-mail: xmjbq007@163.com; Yang, Zheng-Qiang, E-mail: ntdoctoryang@hotmail.com; Liu, Sheng, E-mail: liusheng1137@sina.com

PurposeTo evaluate the clinical effectiveness of a newly designed stent for the treatment of malignant distal duodenal stenosis.MethodsFrom March 2011 to May 2013, six patients with malignant duodenal stenosis underwent fluoroscopically guided placement of the new duodenal stent consisting of braided, nested stent wires, and a delivery system with a metallic mesh inner layer. Primary diseases were pancreatic cancer in three patients, gastric cancer in two patients, and endometrial stromal sarcoma in one patient. Duodenal obstructions were located in the horizontal part in two patients, the ascending part in two patients, and the duodenojejunal flexure in two patients. Technical success,more » defined as the successful stent deployment, clinical symptoms before and after the procedure, and complications were evaluated.ResultsTechnical success was achieved in all patients. No major complications were observed. Before treatment, two patients could not take any food and the gastric outlet obstruction scoring system (GOOSS) score was 0; the other four patients could take only liquids orally (GOOSS score = 1). After treatment, five patients could take soft food (GOOSS score = 2) and one patient could take a full diet (GOOSS score = 3). The mean duration of primary stent patency was 115.7 days.ConclusionsThe newly designed stent is associated with a high degree of technical success and good clinical outcome and may be clinically effective in the management of malignant distal duodenal obstruction.« less

Proximal protection with the Gore PAES can reduce DWI lesion size in high-grade stenosis during carotid stenting.

PubMed

Grunwald, Iris Quasar; Reith, Wolfgang; Kühn, Anna Luisa; Balami, Joyce S; Karp, Kerstin; Fassbender, Klaus; Walter, Silke; Papanagiotou, Panagiotis; Krick, Christoph

2014-06-01

The aim was to determine the incidence of new ischaemic lesions on diffusion-weighted MR imaging (DWI) in a non-randomised cohort of patients after protected and unprotected carotid artery stent placement using the Parodi Anti-Emboli System (PAES). A retrospective review was conducted on 269 patients who received DWI prior to, and 24-72 hours after, stent placement. All patients were enrolled in one centre. Forty patients stented with the PAES device were matched with 229 patients stented without protection (control group). New diffusion restriction on DWI was detected in 25.8% (PAES) versus 32.3% (control group); p=0.64. On average there were 0.7 lesions (PAES) versus 0.8 lesions (control group) per patient. The area of lesions was 1.7 (PAES) versus 5.6 mm2. In a subanalysis of patients (32 PAES, 148 non-protected) with >80% stenosis, the area of restricted diffusion was less when proximal protection was used (p<0.05). The number and area of DWI lesions did not differ on the contralateral, non-stented side. When the PAES system was used, patients were more likely not to have any lesion at all (p=0.028). In high-grade stenosis, the use of the Gore PAES device significantly reduced the area of new DWI lesions and patients were more likely not to have any new DWI lesion at all.

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

PubMed Central

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

2014-01-01

Incomplete endothelialization, blood cell adhesion to vascular stents, and inflammation of arteries can result in acute stent thromboses. The systemic administration of acetylsalicylic acid decreases endothelial dysfunction, potentially reducing thrombus, enhancing vasodilatation, and inhibiting the progression of atherosclerosis; but, this is weakened by upper gastrointestinal bleeding. This study proposes a hybrid stent with biodegradable nanofibers, for the local, sustained delivery of acetylsalicylic acid to injured artery walls. Biodegradable nanofibers are prepared by first dissolving poly(D,L)-lactide-co-glycolide and acetylsalicylic acid in 1,1,1,3,3,3-hexafluoro-2-propanol. The solution is then electrospun into nanofibrous tubes, which are then mounted onto commercially available bare-metal stents. In vitro release rates of pharmaceuticals from nanofibers are characterized using an elution method, and a highperformance liquid chromatography assay. The experimental results suggest that biodegradable nanofibers release high concentrations of acetylsalicylic acid for three weeks. The in vivo efficacy of local delivery of acetylsalicylic acid in reducing platelet and monocyte adhesion, and the minimum tissue inflammatory reaction caused by the hybrid stents in treating denuded rabbit arteries, are documented. The proposed hybrid stent, with biodegradable acetylsalicylic acid-loaded nanofibers, substantially contributed to local, sustained delivery of drugs to promote re-endothelialization and reduce thrombogenicity in the injured artery. The stents may have potential applications in the local delivery of cardiovascular drugs. Furthermore, the use of hybrid stents with acetylsalicylic acid-loaded nanofibers that have high drug loadings may provide insight into the treatment of patients with high risk of acute stent thromboses. PMID:24421640

A preliminary report on the effects of paclitaxel-impregnated stents on sheep nasal mucosa.

PubMed

Herrmann, Brian W; Citardi, Martin J; Vogler, George; Gardner, Laura; Smith, Greg; Javer, Amin R; Burt, Helen M; Jackson, John; Kuhn, Frederick A

2004-01-01

Traditional frontal sinus stents serve only as mechanical devices. It has been proposed that stents also may serve as drug-delivery systems for the topical application of drugs that minimize postoperative scarring. Paclitaxel (Taxol), which has recognized antiscarring effects, may be incorporated via a polymeric formulation into standard rubber stents. The impact of topically applied paclitaxel on the morphology of the nasal mucosa is unknown. An adult sheep model was used for this study. A modified rubber T-tube stent (incorporating paclitaxel at varying dosages) was secured to each side of the septum in four animals (eight sides). An unmodified T-tube was placed on each side of one animal, a T-tube with the drug carrier (but no paclitaxel) was placed on each side of the second animal, and T-tubes with varying paclitaxel were placed on each side of the final two animals. After 4 weeks, animals were killed and the nasal mucosa was harvested. The nasal mucosa was sectioned and stained with hematoxylin and eosin. A pathologist then assessed the nasal mucosa for vascular congestion, glandular atrophy, chronic inflammation, mucosal metaplasia, and mucosal ulceration. No consistent histopathological differences were noted in the specimens. All specimens showed varying degrees of vascular congestion, glandular atrophy, chronic inflammation, and mucosal metaplasia; the paclitaxel-impregnated stents were not consistently associated with more severe mucosal injury. Finally, mucosal ulceration was noted to be very rare in all specimens. This preliminary report describes the impact of paclitaxel-impregnated stents on sheep nasal mucosa, which tolerated these stents very well. Because paclitaxel minimizes scarring reactions at very low concentrations, paclitaxel-impregnated stents may prove useful in clinical situations in which frontal sinus stenting is deemed necessary. Additional investigations with animal models, as well as clinical trials, may be warranted.

Intracoronary beta-radiation for the treatment of patients at very high risk for recurrence of in-stent restenosis: a single center experience.

PubMed

Parenti, Dennis Zavalloni; Marsico, Federica; Tosi, Giovanni; Catalano, Gianpiero; Maiello, Luigi; Milone, Francesco; Carcagnì, Addolorata; Pron, Paolo Giay; Orecchia, Roberto; Presbitero, Patrizia

2003-03-01

Intracoronary brachytherapy has significantly reduced the recurrence of in-stent restenosis. The aim of this study was to evaluate the feasibility, safety and efficacy of intracoronary beta-radiation in patients at very high risk for recurrence of in-stent restenosis. We analyzed 42 patients with 50 lesions submitted to catheter-based beta-radiation (Beta-Cath System, Novoste Corporation, Norcross, GA, USA) for in-stent restenosis. Thirty-eight lesions were at the second restenosis, 8 at the third, and 4 at the fourth; a diffuse pattern was present in 78%. Balloon angioplasty was performed for 30 lesions (60%) and the cutting balloon technique for 20 (40%). In 12 lesions further 14 stents had to be deployed (28%). The delivery catheter was successfully positioned in 96% of the procedures. The mean dwell time was 179 +/- 50 s with a radiation dose ranging from 18.4 to 25.3 Gy, depending on the vessel size. A complete angiographic success without coronary dissection and without any additional stenting after radiation delivery was achieved in 86%. At follow-up (7.2 +/- 2.1 months), the overall restenosis rate was 30.4% (14 lesions). A recurrence was detected in 1/11 lesions with initial focal pattern and in 13/39 lesions with initial diffuse pattern. The restenosis rate was higher in patients in whom a geographic miss had occurred (p < 0.05 vs lesions without geographic miss) and in those in whom a new stent had been deployed (p < 0.05 vs lesions treated without a stent). Brachytherapy reduces the in-stent restenosis rate in patients who are at very high risk of recurrence. The restenosis pattern, geographic miss and new stent deployment seem to be negative prognostic factors for recurrence of restenosis.

Transhepatic implant of a trimmed Melody™ valved stent in tricuspid position in a 1-year-old infant.

PubMed

Cools, Bjorn; Rega, Filip; Gewillig, Marc

2017-02-15

Percutaneous valved stent implantation is precluded in small infants because large delivery sheaths and large devices. We describe a procedure in a 1-year-old boy in whom a 19 mm Epic™ valve in tricuspid position had become dysfunctional. As the internal diameter of the prosthetic valve was about 16 mm, the only available valve was the Melody™ valved stent. Technical modifications were required to address issues like venous access, the bulky delivery system, and the length of the valved stent. The Melody™ valved stent was surgically trimmed and mounted on a 16 mm Tyshak balloon, access was provided transhepatically through a short 18 Fr sheath. After deployment, the intrahepatic route was sealed with two vascular plugs (8 and 10 mm) in tandem. The procedure was uncomplicated with perfect valve function 18 months after implant. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Bloody tears and recurrent nasolacrimal duct obstruction due to a retained silicone stent.

PubMed

Kemp, Pavlina S; Allen, Richard C

2014-06-01

A 6-year-old girl with a history of bilateral nasolacrimal duct obstruction presented with recurrent tearing, discharge, and bloody tears from the right eye. The patient had a history of multiple prior probing and stenting procedures on the right nasolacrimal system. Endoscopic dacryocystorhinotomy revealed a retained portion of a prior stent and accompanying pyogenic granuloma, removal of which resolved her symptoms. Copyright © 2014 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

Double bifurcation optimization stent system technique for left main stenosis.

PubMed

Vassilev, D; Mateev, H; Alexandrov, A; Karamfiloff, K; Gil, R J

2014-12-01

We present a first-in-man case with implantation in culottes' fashion of two dedicated coronary bifurcation stents (BiOSS Lim) in distal left main stenosis. The immediate procedural and very short-term result was excellent. © 2014, Wiley Periodicals, Inc.

Multiple Coaxial Catheter System for Reliable Access in Interventional Stroke Therapy

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

Kulcsar, Zsolt, E-mail: kulcsarzsolt22@gmail.com; Yilmaz, Hasan; Bonvin, Christophe

2010-12-15

In some patients with acute cerebral vessel occlusion, navigating mechanical thrombectomy systems is difficult due to tortuous anatomy of the aortic arch, carotid arteries, or vertebral arteries. Our purpose was to describe a multiple coaxial catheter system used for mechanical revascularization that helps navigation and manipulations in tortuous vessels. A triple or quadruple coaxial catheter system was built in 28 consecutive cases presenting with acute ischemic stroke. All cases were treated by mechanical thrombectomy with the Penumbra System. In cases of unsuccessful thrombo-aspiration, additional thrombolysis or angioplasty with stent placement was used for improving recanalization. The catheter system consisted ofmore » an outermost 8-Fr and an intermediate 6-Fr guiding catheter, containing the inner Penumbra reperfusion catheters. The largest, 4.1-Fr, reperfusion catheter was navigated over a Prowler Select Plus microcatheter. The catheter system provided access to reach the cerebral lesions and provided stability for the mechanically demanding manipulations of thromboaspiration and stent navigation in all cases. Apart from their mechanical role, the specific parts of the system could also provide access to different types of interventions, like carotid stenting through the 8-Fr guiding catheter and intracranial stenting and thrombolysis through the Prowler Select Plus microcatheter. In this series, there were no complications related to the catheter system. In conclusion, building up a triple or quadruple coaxial system proved to be safe and efficient in our experience for the mechanical thrombectomy treatment of acute ischemic stroke.« less

Application of High Entropy Alloys in Stent Implants

NASA Astrophysics Data System (ADS)

Alagarsamy, Karthik

High entropy alloys (HEAs) are alloys with five or more principal elements. Due to these distinct concept of alloying, the HEA exhibits unique and superior properties. The outstanding properties of HEA includes higher strength/hardness, superior wear resistance, high temperature stability, higher fatigue life, good corrosion and oxidation resistance. Such characteristics of HEA has been significant interest leading to researches on these emerging field. Even though many works are done to understand the characteristic of these HEAs, very few works are made on how the HEAs can be applied for commercial uses. This work discusses the application of High entropy alloys in biomedical applications. The coronary heart disease, the leading cause of death in the United States kills more than 350,000 persons/year and it costs $108.9 billion for the nation each year in spite of significant advancements in medical care and public awareness. A cardiovascular disease affects heart or blood vessels (arteries, veins and capillaries) or both by blocking the blood flow. As a surgical interventions, stent implants are deployed to cure or ameliorate the disease. However, the high failure rate of stents has lead researchers to give special attention towards analyzing stent structure, materials and characteristics. Many works related to alternate material and/or design are carried out in recent time. This paper discusses the feasibility of CoCrFeNiMn and Al0.1CoCrFeNi HEAs in stent implant application. This work is based on the speculation that CoCrFeNiMn and Al0.1CoCrFeNi HEAs are biocompatible material. These HEAs are characterized to determine the microstructure and mechanical properties. Computational modeling and analysis were carried out on stent implant by applying CoCrFeNiMn and Al0.1CoCrFeNi HEAs as material to understand the structural behavior.

One swallow does not a summer make but many swallows do: accumulating clinical evidence for nearly-eliminated peri-procedural and 30-day complications with mesh-covered stents transforms the carotid revascularisation field

PubMed Central

Hopkins, L. Nelson; Siddiqui, Adnan H.

2017-01-01

Atherosclerotic carotid artery stenosis (CS) continues to be a common cause of acute ischaemic stroke. Optimised medical therapy (OMT), the first-line treatment modality in CS, may reduce or delay – but it does not abolish – CS-related strokes. As per current AHA/ASA and ESC/ESVS/ESO guidelines, carotid artery stenting (CAS) is a less-invasive alternative to carotid endarterectomy (CEA) for CS revascularisation in primary and secondary stroke prevention. Ten-year follow-up from the CREST trial in patients with symptomatic and asymptomatic CS confirmed equipoise of CAS and CEA in the primary endpoint. Nevertheless CAS – using a widely open-cell, first-generation stent and first-generation (distal/filter) neuroprotection – has been criticised for its relative excess of (mostly minor) strokes by 30 days, a significant proportion of which were post-procedural. Atherosclerotic plaque protrusion through conventional carotid stent struts, confirmed on intravascular imaging, has been implicated as a leading mechanism of the relative excess of strokes with CAS vs. CEA, including delayed strokes with CAS. Different designs of mesh-covered carotid stents have been developed to prevent plaque prolapse. Several multi-centre/multi-specialty clinical studies with CGurad MicroNet-Covered Embolic Prevention Stent System (EPS) and RoadSaver/Casper were recently published and included routine DW-MRI cerebral imaging peri-procedurally and at 30 days (CGuard EPS). Data from more than 550 patients in mesh-covered carotid stent clinical studies to-date show an overall 30-day complication rate of ~1% with near-elimination of post-procedural events. While more (and long-term) evidence is still anticipated, these results – taken together with optimised intra-procedural neuroprotection in CAS (increased use of proximal systems including trans-carotid dynamic flow reversal) and the positive 12-month mesh-covered stent data reports in 2017 – are transforming the carotid revascularisation field today. Establishing effective algorithms to identify the asymptomatic subjects at stroke risk despite OMT, and large-scale studies with mesh-covered stents including long-term clinical and duplex ultrasound outcomes, are the next major goals. PMID:28798779

Percutaneous coronary intervention with second-generation paclitaxel-eluting stents versus everolimus-eluting stents in United States contemporary practice (REWARDS TLX Trial).

PubMed

Waksman, Ron; Ghali, Magdi; Goodroe, Randy; Ryan, Thomas; Turco, Mark; Ring, Michael; McGarry, Thomas; Dobies, David; Shammas, Nicolas; Steinberg, Daniel H; Swymelar, Stacy; Kaneshige, Kimberly; Torguson, Rebecca

2012-10-15

Registry Experience at the Washington Hospital Center, DES - Taxus Liberte Versus Xience V (REWARDS TLX) is a physician-initiated, retrospective, real-world, multicenter, observational study for all patients >18 years of age subjected to percutaneous coronary intervention with everolimus-eluting stents (EESs) or paclitaxel-eluting stents (PESs). Outcomes of patients receiving a TAXUS Liberté or XIENCE V drug-eluting stent were compared. Baseline clinical, procedural, and follow-up data at 12 months were collected from 10 clinical centers by an electronic data capture system. The study's primary end point was major adverse cardiac events: a composite of all-cause death, Q-wave myocardial infarction, target vessel revascularization, and stent thrombosis. The trial is registered with http://www.clinicaltrials.gov (NCT01134159). Data were entered for 1,195 patients (PES, n = 595; EES, n = 600). Baseline clinical characteristics were similar except for higher dyslipidemia, systemic hypertension, and family history of coronary artery disease in the EES group. In-hospital outcome was similar between groups, with an overall in-hospital stent thrombosis rate of 0.2%. The primary end point at 12 months was similar (EES 7.8% vs 10.8%, p = 0.082). Overall stent thrombosis rate was lower in the EES group (0.3% vs 1.2%, respectively, p = 0.107); however, target lesion revascularization was similar (PES, hazard ratio 1.46, 95% confidence interval 0.98 to 2.19, p = 0.064). There was no difference in overall mortality between groups. In conclusion, second-generation EESs and PESs demonstrated similar efficacy and safety profiles for broadened patient and lesion subsets compared to a selected population from the pivotal trials. However, for composite efficacy and safety end points, EESs outperformed second-generation PESs. Copyright © 2012 Elsevier Inc. All rights reserved.

Computational comparison of aortic root stresses in presence of stentless and stented aortic valve bio-prostheses.

PubMed

Nestola, M G C; Faggiano, E; Vergara, C; Lancellotti, R M; Ippolito, S; Antona, C; Filippi, S; Quarteroni, A; Scrofani, R

2017-02-01

We provide a computational comparison of the performance of stentless and stented aortic prostheses, in terms of aortic root displacements and internal stresses. To this aim, we consider three real patients; for each of them, we draw the two prostheses configurations, which are characterized by different mechanical properties and we also consider the native configuration. For each of these scenarios, we solve the fluid-structure interaction problem arising between blood and aortic root, through Finite Elements. In particular, the Arbitrary Lagrangian-Eulerian formulation is used for the numerical solution of the fluid-dynamic equations and a hyperelastic material model is adopted to predict the mechanical response of the aortic wall and the two prostheses. The computational results are analyzed in terms of aortic flow, internal wall stresses and aortic wall/prosthesis displacements; a quantitative comparison of the mechanical behavior of the three scenarios is reported. The numerical results highlight a good agreement between stentless and native displacements and internal wall stresses, whereas higher/non-physiological stresses are found for the stented case.

Transpopliteal stenting of femoral occlusions in patients with critical limb ischemia using a 4-French system.

PubMed

Spreen, Marlon; Vink, Ted; Knippenberg, Bob; Reekers, Jim; van Dijk, Lukas; Wever, Jan; van Eps, Randolph; van Overhagen, Hans

2014-08-01

In many patients with critical limb ischemia (CLI), transfemoral endovascular recanalization is the preferred treatment. Transpopliteal treatment may be used in patients with inaccessible groins. This retrospective study regards transpopliteal stenting of superficial femoral artery (SFA) occlusions using a 4F system. Eleven patients (4 male and 7 female [mean age 77 years]) underwent 12 attempts of transpopliteal recanalization of long SFA occlusions (Trans-Atlantic InterSociety Consensus B through D). All patients had CLI (Rutherford 4 to 6) and were nonoperable due to poor general condition. Indications for transpopliteal access were proximal/flush SFA occlusions (n = 5), failure of antegrade recanalization (n = 4), infected femoral-femoral crossover bypass (n = 2), and occlusion of both the native SFA and the femoral-popliteal bypass (n = 1). The popliteal artery was punctured under ultrasound guidance. Occlusions were recanalized subintimally, and 4F compatible stents were implanted. Technical success rate (<30 % residual stenosis) was achieved in 83 % of cases. In two patients, stent dislocation occurred while the sheath was removed. One arteriovenous fistula was successfully treated with additional stenting. During 6-month follow-up, there were no major amputations, and three patients died from nonrelated causes. Fifty percent of patients alive after 6 months improved to Rutherford score ≤3. The duplex restenosis (>50 %) rate at 6 months was 50 %. Transpopliteal primary stenting of complex SFA lesions in CLI for a temporary bypass is now technically feasible using a 4F system. Technical results are promising. Clinical results after 6 months are acceptable when taking into consideration that this approach may be the last option for limb salvage.

Prospective evaluation of a newly designed T-configured stent graft system for palliative treatment of advanced hilar malignant biliary obstructions.

PubMed

Gwon, Dong Il; Ko, Gi-Young; Yoon, Hyun-Ki; Kim, Jin Hyoung; Lee, Jae Myeong; Ohm, Joon-Young; Sung, Kyu-Bo

2010-09-01

To investigate the technical and clinical safety and efficacy of using a newly designed T-configured stent graft for palliative treatment of advanced hilar malignant biliary obstructions. This is a prospective study that enrolled 30 patients who had malignant hilar obstructions from May 2007 to November 2008. All patients were treated with percutaneous transhepatic placement of two specially designed stent grafts in a T configuration. Technical success, evaluation of blocked branching ducts, complications, clinical success, stent patency time, and patient survival rates were analyzed. Stent graft deployment was technically successful in all patients. The bilirubin level and the bile duct diameter decreases were statistically significant after stent placement (P < .001), and all patients showed clinical improvement. Minor complications, including procedure-related complications (self-limiting hemobilia [n = 3], perihepatic biloma [n = 1], and acute pancreatitis [n = 1]) and rapidly resolving cholangitis (n = 5), occurred in ten patients (33.3%). Major complications, including acute cholecystitis, occurred in three patients (10%). Stent occlusion occurred in 12 patients (40%) after a mean period of 160 days (range, 82-307 days). The median survival and stent patency times were 334 days (range, 195.6-472.4 days) and 279 days (range, 194.7-363.3 days), respectively. There were no statistical differences in age, sex, Bismuth type, or number of blocked branching ducts. The initial results of percutaneous palliative treatment of advanced hilar malignancies with T-configured stent grafts suggest that they are safe and potentially clinically effective. Copyright 2010 SIR. Published by Elsevier Inc. All rights reserved.

Final five-year clinical outcomes in the EVOLVE trial: a randomised evaluation of a novel bioabsorbable polymer-coated, everolimus-eluting stent.

PubMed

Meredith, Ian T; Verheye, Stefan; Dubois, Christophe; Dens, Joseph; Farah, Bruno; Carrié, Didier; Walsh, Simon; Oldroyd, Keith; Varenne, Olivier; El-Jack, Seif; Moreno, Raul; Christen, Thomas; Allocco, Dominic J

2018-04-20

Long-term data on bioabsorbable polymer-coated everolimus-eluting stents (BP-EES) are limited. The EVOLVE trial compared the safety and efficacy of two dose formulations of the SYNERGY BP-EES with the permanent polymer-coated PROMUS Element EES (PE). The EVOLVE study was a prospective, multicentre, non-inferiority trial that randomised 291 patients with de novo coronary lesions (length: ≤28 mm; diameter: ≥2.25 to ≤3.5 mm) to receive PE (n=98), SYNERGY (n=94), or SYNERGY half-dose (n=99). At five years, there were no significant differences in the rates of TLF or individual components between groups. TLR rates trended lower in both SYNERGY arms than in the PE arm (TLR: 1.1% SYNERGY and 1.0% SYNERGY half-dose vs. 6.1% PE; p=0.07 and p=0.06, respectively). TVR was numerically lower in the SYNERGY arms compared to the PE arm (TVR: 3.3% SYNERGY and 4.2% SYNERGY half-dose vs. 10.2% PE; p=0.06 and p=0.11, respectively). No incidence of stent thrombosis was reported in any arm up to five years. The EVOLVE trial represents the longest-term follow-up of the SYNERGY stent available to date, demonstrating its continued safety and efficacy for the treatment of selected de novo atherosclerotic lesions up to five years.

Effects of the temporary placement of a self-expandable metallic stent in benign pyloric stenosis.

PubMed

Choi, Won Jae; Park, Jong-Jae; Park, Jain; Lim, Eun-Hye; Joo, Moon Kyung; Yun, Jae-Won; Noh, Hyejin; Kim, Sung Ho; Choi, Woo Seok; Lee, Beom Jae; Kim, Ji Hoon; Yeon, Jong Eun; Kim, Jae Seon; Byun, Kwan Soo; Bak, Young-Tae

2013-07-01

The use of self-expandable metallic stents (SEMS) is an established palliative treatment for malignant stenosis in the gastrointestinal tract; therefore, its application to benign stenosis is expected to be beneficial because of the more gradual and sustained dilatation in the stenotic portion. We aimed in this prospective observational study to evaluate the efficacy and safety of temporary SEMS placement in benign pyloric stenosis. Twenty-two patients with benign stenosis of the prepylorus, pylorus, and duodenal bulb were enrolled and underwent SEMS placement. We assessed symptom improvement, defined as an increase of at least 1 degree in the gastric-outlet-obstruction scoring system after stent insertion. No major complications were observed during the procedures. After stent placement, early symptom improvement was achieved in 18 of 22 patients (81.8%). During the follow-up period (mean 10.2 months), the stents remained in place successfully for 6 to 8 weeks in seven patients (31.8%). Among the 15 patients (62.5%) with stent migration, seven (46.6%) showed continued symptomatic improvement without recurrence of obstructive symptoms. Despite the symptomatic improvement, temporary SEMS placement is premature as an effective therapeutic tool for benign pyloric stenosis unless a novel stent is developed to prevent migration.

Effects of the Temporary Placement of a Self-Expandable Metallic Stent in Benign Pyloric Stenosis

PubMed Central

Choi, Won Jae; Park, Jain; Lim, Eun-Hye; Joo, Moon Kyung; Yun, Jae-Won; Noh, Hyejin; Kim, Sung Ho; Choi, Woo Seok; Lee, Beom Jae; Kim, Ji Hoon; Yeon, Jong Eun; Kim, Jae Seon; Byun, Kwan Soo; Bak, Young-Tae

2013-01-01

Background/Aims The use of self-expandable metallic stents (SEMS) is an established palliative treatment for malignant stenosis in the gastrointestinal tract; therefore, its application to benign stenosis is expected to be beneficial because of the more gradual and sustained dilatation in the stenotic portion. We aimed in this prospective observational study to evaluate the efficacy and safety of temporary SEMS placement in benign pyloric stenosis. Methods Twenty-two patients with benign stenosis of the prepylorus, pylorus, and duodenal bulb were enrolled and underwent SEMS placement. We assessed symptom improvement, defined as an increase of at least 1 degree in the gastric-outlet-obstruction scoring system after stent insertion. Results No major complications were observed during the procedures. After stent placement, early symptom improvement was achieved in 18 of 22 patients (81.8%). During the follow-up period (mean 10.2 months), the stents remained in place successfully for 6 to 8 weeks in seven patients (31.8%). Among the 15 patients (62.5%) with stent migration, seven (46.6%) showed continued symptomatic improvement without recurrence of obstructive symptoms. Conclusions Despite the symptomatic improvement, temporary SEMS placement is premature as an effective therapeutic tool for benign pyloric stenosis unless a novel stent is developed to prevent migration. PMID:23898381

Wave reflection and transmission in multiply stented blood vessels

NASA Astrophysics Data System (ADS)

Papathanasiou, T. K.; Movchan, A. B.; Bigoni, D.

2017-06-01

Closed circulatory systems display an exquisite balance between vascular elasticity and viscous fluid effects, to induce pulse-smoothing and avoid resonance during the cardiac cycle. Stents in the arterial tree alter this balance through stiffening and because a periodic structure is introduced, capable of interacting with the fluid in a complex way. While the former feature has been investigated, the latter received no attention so far. But periodic structures are the building blocks of metamaterials, known for their `non-natural' behaviour. Thus, the investigation of a stent's periodic microstructure dynamical interactions is crucial to assess possible pathological responses. A one-dimensional fluid-structure interaction model, simple enough to allow an analytical solution for situations of interest involving one or two interacting stents, is introduced. It is determined: (i) whether or not frequency bands exist in which reflected blood pulses are highly increased and (ii) if these bands are close to the characteristic frequencies of arteries and finally, (iii) if the internal structure of the stent can sensibly affect arterial blood dynamics. It is shown that, while the periodic structure of an isolated stent can induce anomalous reflection only in pathological conditions, the presence of two interacting stents is more critical, and high reflection can occur at frequencies not far from the physiological values.

Wave reflection and transmission in multiply stented blood vessels

PubMed Central

Movchan, A. B.

2017-01-01

Closed circulatory systems display an exquisite balance between vascular elasticity and viscous fluid effects, to induce pulse-smoothing and avoid resonance during the cardiac cycle. Stents in the arterial tree alter this balance through stiffening and because a periodic structure is introduced, capable of interacting with the fluid in a complex way. While the former feature has been investigated, the latter received no attention so far. But periodic structures are the building blocks of metamaterials, known for their ‘non-natural’ behaviour. Thus, the investigation of a stent's periodic microstructure dynamical interactions is crucial to assess possible pathological responses. A one-dimensional fluid–structure interaction model, simple enough to allow an analytical solution for situations of interest involving one or two interacting stents, is introduced. It is determined: (i) whether or not frequency bands exist in which reflected blood pulses are highly increased and (ii) if these bands are close to the characteristic frequencies of arteries and finally, (iii) if the internal structure of the stent can sensibly affect arterial blood dynamics. It is shown that, while the periodic structure of an isolated stent can induce anomalous reflection only in pathological conditions, the presence of two interacting stents is more critical, and high reflection can occur at frequencies not far from the physiological values. PMID:28690408

The STENTYS self-apposing stent technology in coronary artery disease: literature review and future directions.

PubMed

Lu, Huangling; de Winter, Robbert J; Koch, Karel T

2018-06-21

Coronary stent designs have been through extensive developments in the past few decades. Since the first introduction of the self-apposing STENTYS stent, several theoretical advantages of its nitinol platform have been clinically evaluated. This paper reviews the current status, ongoing work and future directions of this device. Areas covered: The OPEN (STENTYS Coronary Bifurcation Stent System fOr the PErcutaNeous treatment of de novo lesions in native bifurcated coronary arteries) trials revealed high technical success rates of the STENTYS performance in bifurcation lesions. The APPOSITION (Assessment of the Safety and Performance of the STENTYS self-expanding Coronary Stent in Acute Myocardial Infarction) trials demonstrated the safety and feasibility of the device in patients with acute myocardial infarction. Optical coherence tomography showed better short-term strut apposition in patients treated with the STENTYS stent in APPOSITION IV. The clinical outcomes of the device in saphenous vein graft lesions and left main coronary artery disease are favourable. Expert Commentary: Despite numerous theoretical advantages of the nitinol platform, superiority of the STENTYS self-apposing stent over currently available DES has not yet been proven. However, the ongoing registries evaluating the performance of the STENTYS Xposition will provide more insights in its clinical performance.

Demonstration of bacterial biofilms in culture-negative silicone stent and jones tube.

PubMed

Parsa, Kami; Schaudinn, Christoph; Gorur, Amita; Sedghizadeh, Parish P; Johnson, Thomas; Tse, David T; Costerton, John W

2010-01-01

To demonstrate the presence of bacterial biofilms on a dacryocystorhinostomy silicone stent and a Jones tube. One dacryocystorhinostomy silicone stent and one Jones tube were removed from 2 patients who presented with an infection of their respective nasolacrimal system. Cultures were obtained, and the implants were processed for scanning electron microscopy and confocal laser scanning microscopy, advanced microscopic methods that are applicable for detection of uncultivable biofilm organisms. Routine bacterial cultures revealed no growth, but bacterial biofilms on outer and inner surfaces of both implants were confirmed by advanced microscopic techniques. To the authors' knowledge, this is the first article that documents the presence of biofilms on a Crawford stent or a Jones tube on patients who presented with infections involving the nasolacrimal system. Although initial cultures revealed absence of any bacterial growth, confocal laser scanning microscopy and scanning electron microscopy documented bacterial colonization. Clinicians should consider the role of biofilms and the limitation of our standard culturing techniques while treating patients with device- or implant-related infections.

Nasojejunal-stent technique (NJST): A new system to prevent fully covered metal stent migration in the treatment of benign esophageal diseases.

PubMed

Hernández Mondragón, Oscar Víctor; Cuellar, Raquel Palos; Murcio Pérez, Enrique

2018-05-19

Fully covered self-expandable metal stents (FCSEMS) have been used for the treatment of benign esophageal conditions such as perforation, leaks, and strictures [1]; high clinical success is reported [2]. Different anchoring methods have been described (clips, suturing devices, over-the-scope clips and Shim technique [2]), because of high migration rates (4-36%) [3,4]. However, not all cases are candidates, mostly in "difficult" cases where enteral feeding is needed [5]. We report the use of the nasojejunal-stent technique (NJST) to prevent migration of FCSEMS in three difficult cases. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

[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 stent. The stents remained stable, no migration occurred, no empyema recurred, and the patient with broncho-esophageal fistula fed and drunk well. The use of fully covered self-expandable stents proved to be a safe, effective and fast minimally invasive method to treat airway fistula, especially for patients with a higher surgical risk or other failed treatments.

Treatment of bifurcation in-stent restenotic lesions with beta radiation using strontium 90 and sequential positioning pullback technique: procedural details and clinical outcomes.

PubMed

Costa, Ricardo; Joyal, Michel; Harel, Francois; Fox, Tim; Crocker, Ian; Arsenault, Andre; Gregoire, Jean; Bonan, Raoul

2003-08-01

In-stent restenotic lesions have been problematic for many patients with the need for multiple repeat percutaneous coronary interventions (PCI). The need for repeat PCI has been significantly reduced in patients since the advent of vascular brachytherapy. In-stent restenosis resulting in bifurcation presents even more of a challenge. The use of radiation therapy for the treatment of this kind of lesion has not yet been reported. The purpose of this paper is to present five cases of radiation therapy in bifurcation in-stent restenotic lesions using the intraluminal beta radiation catheter delivery system (Beta-Cath System, Novoste Corporation, Norcross, Georgia). We reviewed the database of patients enrolled in our Compassionate Use Registry between August 1999 and April 2002. The data is reported for 5 patients who received radiation in both branches of bifurcation lesions with the Beta-Cath catheter system. The mean diameter of the vessels was 3.1 mm 0.5 mm. The dose administered was from 18.3 to 23 Gy, with an overlap of 3.3 to 10.3 mm; the hinge angle between the branches went from 43.3 to 65.4 . Angiographic follow-up was obtained at 6 months in 4 patients, with a single patient showing a focal (< 5 mm) edge lesion treated by balloon angioplasty (TVR no TLR). No aneurysms or zones of ectasia were noted. Beta radiation with the Beta-Cath catheter system appears to be safe, secure and clinically useful in in-stent restenotic bifurcation lesions.

Covered self-expandable metal stents with an anti-migration system improve patency duration without increased complications compared with uncovered stents for distal biliary obstruction caused by pancreatic carcinoma: a randomized multicenter trial.

PubMed

Kitano, Masayuki; Yamashita, Yukitaka; Tanaka, Kiyohito; Konishi, Hideyuki; Yazumi, Shujiro; Nakai, Yoshitaka; Nishiyama, Osamu; Uehara, Hiroyuki; Mitoro, Akira; Sanuki, Tsuyoshi; Takaoka, Makoto; Koshitani, Tatsuya; Arisaka, Yoshifumi; Shiba, Masatsugu; Hoki, Noriyuki; Sato, Hideki; Sasaki, Yuichi; Sato, Masako; Hasegawa, Kazunori; Kawabata, Hideaki; Okabe, Yoshihiro; Mukai, Hidekazu

2013-11-01

The requirements of biliary stents used in the palliation of malignant biliary obstruction are a long duration of patency and minimal adverse effects. Covered self-expandable metal stents (SEMSs) have been shown to prevent tumor ingrowth, which is the most frequent complication of uncovered SEMSs. However, because they are prone to migration, the superiority of covered SEMS has yet to be convincingly demonstrated. The aim of this study was to evaluate the superiority of covered over uncovered SEMSs in the palliation of distal biliary obstruction due to unresectable pancreatic carcinoma, using both stent types with relatively low axial force and uncovered flared ends to prevent their migration. From April 2009 to December 2010, 120 patients who were admitted to 22 tertiary-care centers because of distal biliary obstruction from unresectable pancreatic carcinomas were enrolled in this prospective randomized multicenter study. Patients were randomly assigned to receive a covered or uncovered SEMS deployed at the site of the biliary stricture during endoscopic retrograde cholangiopancreatography. Stent patency time, patient survival time, patient survival time without stent dysfunction (time to stent dysfunction or patient death), cause of stent dysfunction (ingrowth, overgrowth, migration, or sludge formation), and serious adverse events were compared between covered and uncovered SEMS groups. Patient survival time in the two groups did not significantly differ (median: 285 and 223 days, respectively; P=0.68). Patient survival time without stent dysfunction was significantly longer in the covered than in the uncovered SEMS group (median: 187 vs. 132 days; P=0.043). Stent patency was also significantly longer in the covered than in the uncovered SEMS group (mean±s.d.: 219.3±159.1 vs. 166.9±124.9 days; P=0.047). Reintervention for stent dysfunction was performed in 14 of 60 patients with covered SEMSs (23%) and in 22 of 60 patients with uncovered SEMSs (37%; P=0.08). Stent dysfunction was caused by tumor ingrowth, tumor overgrowth, and sludge formation in 0 (0%), 3 (5%), and 11 (18%) patients in the covered SEMSs group, and in 15 (25%), 2 (3%), and 6 (10%) patients in the uncovered SEMSs group, respectively. Stent migration was not observed in either group. Rates of tumor overgrowth and sludge formation did not significantly differ between the two groups, whereas the rate of tumor ingrowth was significantly lower in the covered than in the uncovered SEMS group (P<0.01). Acute pancreatitis occurred in only one patient in the covered SEMS group. Acute cholecystitis occurred in one patient in the covered SEMS group and in two patients in the uncovered SEMS group. There was no significant difference between the two groups in the incidence of serious adverse events. By preventing tumor ingrowth and migration, covered SEMSs with an anti-migration system had a longer duration of patency than uncovered SEMSs, which recommends their use in the palliative treatment of patients with biliary obstruction due to pancreatic carcinomas.

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

NASA Astrophysics Data System (ADS)

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

2015-01-01

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

Assessment of vesicoureteral reflux in patients with self-retaining ureteral stents: implications for upper urinary tract instillation.

PubMed

Yossepowitch, Ofer; Lifshitz, David A; Dekel, Yoram; Ehrlich, Yaron; Gur, Uri; Margel, David; Livne, Pinhas M; Baniel, Jack

2005-03-01

Conservative treatment of upper urinary tract tumors has been popularized during the last decade. Like in bladder cancer management, localized adjuvant therapy has been advocated to reduce the risk of disease recurrence or progression. In this study we tested the feasibility of creating vesicoureteral reflux (VUR) using a Double-J stent (Medical Engineering Corp., New York, New York) as a measure of efficacy for intravesical adjuvant treatment of the ureter and renal collecting system. The cohort included 100 consecutive patients in whom a Double-J stent was inserted for renal obstruction. All the patients underwent cystography in the supine position by retrograde filling of the bladder with a 50% dilute solution of 300 mgI/ml iopromide in serial increments of 50 ml up to a maximum of 350 ml. A total of 41 patients underwent cystography immediately following stent insertion (early group) and 59 patients with indwelling stents underwent cystography before further endourological intervention (late group). The presence of VUR and the level along the ureter and renal collecting system were assessed fluoroscopically. Overall VUR was detected in 56 patients (56%), specifically 11 of the 41 (27%) in the early group and 45 of the 59 (76%) in the late group (p <0.001). There was no correlation between stent diameter or length and VUR, or between patient sex, age or particular side and the likelihood of reflux. Mean minimal intravesical volume required to obtain reflux was 171 +/- 11 ml, which was significantly higher in the early (255 +/- 21 ml) than in the late (146 +/- 11 ml) cystogram group. In 24 of the 56 patients (43%) with VUR, there was complete visualization of the entire ureter and renal collecting system. However, 15 patients (26%) had opacified renal pelves and calices without concomitant visualization of the ureters, whereas 7 patients (31%) had reflux to the ureter without opacification of the renal pelvis. VUR is not a guaranteed consequence of Double-J stent placement. Therefore, when upper urinary tract instillation with the Double-J technique is considered, a cystogram should be performed first to confirm the occurrence of reflux, determine the intravesical volume required to induce reflux and ascertain that the pertinent section of the ureter or pelvicaliceal system from which the tumor was initially removed is opacified during study. An interval that remains to be defined should be allowed between stent insertion and VUR assessment.

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

PubMed

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

2004-05-01

To test noninvasive inductive heating of implanted vascular stents as an alternative approach for reduction or prevention of neointimal hyperplasia. Calorimetric pretests were performed to get an orientation on the different parameters of influence for inductive heating of stents. The field strength was set to a maximum of 90 kA/m within a frequency range from 80 kHz to 320 kHz. The electromagnetic field was emitted by a custom-made water-cooled copper winding antenna. A flow model for stent heating was set up to assess the increase in temperature of an expanded 316L stainless steel stent with typical coronary stent dimensions of 3.5 mm diameter and 14.5 mm in length, and in a second setup with 4.5 mm diameter and 13 mm in length, respectively. The stent was located in a bioartificial artery, simulated by a fibrinogen matrix with a defined number of vital cells. The system was exposed to a pulsating perfusion and to an electromagnetic field of 200 kHz over a period of 20 minutes and in a second setup to an electromagnetic field of 300 kHz and increasing intensity up to maximum power-output. Afterward, the artificial vessel was sliced and examined by fluorescence microscopy to evaluate the number and location of damaged cells. The calorimetric tests show an exponential correlation of energy uptake in the stent with an increase in frequency and a constant generator output. At a frequency of 80 kHz, the power uptake accounts for 0.1 W (250 kHz 1.0 W; 320 kHz 1.9 W, respectively). The flow tests confirmed feasibility to elevate the stent temperature from 37 degrees C body temperature to 44 degrees C at 200 kHz within 55 seconds. The temperature increase of the fluid passing the heated vessel region was only marginal (maximum of 0.5 degrees C). Cell necrosis after 20 minutes of treatment was not observed. In a second set-up with 4.5 mm stent diameter, a frequency of 300 kHz and with maximum power output, the stent temperature was increased to 80 degrees C and there was extensive necrosis area around the stent. Treatment time and stent temperature were optimized in further tests. Selective noninvasive energy transfer to coronary stainless steel stents by inductive heating is possible within a wide range of power. By thermal conduction, vital cells close to the stent struts can be affected. The frequency of 200 kHz turned out to be favorable. There is still room for further optimization of energy dosage with regard to material and stent design, to induce controlled cell death. The method has potential to serve as an alternative approach for prevention of instent restenosis.

Modulating the Release Kinetics of Paclitaxel from Membrane-Covered Stents Using Different Loading Strategies

PubMed Central

Sydow-Plum, Georg; Haidar, Ziyad S.; Merhi, Yahye; Tabrizian, Maryam

2008-01-01

Membrane-covered Express2TM Monorail® stents composed of chitosan (CH) blended with polyethylene oxide (PEO) in 70:30% wt (CH-PEO) were coated with a monolayer of hyaluronic acid (HA). This significantly improved the resistance to platelet adhesion and demonstrated excellent mechanical properties, resisting the harsh conditions during stent crimping and subsequent inflation. CH-PEO/HA membrane was then combined with a paclitaxel (Pac) delivery system via three different approaches for comparison of release profiles of Pac. The activity of Pac in these systems was confirmed since its presence in the membrane significantly decreased cell viability of U937 macrophages. Presented results are promising for applications requiring different release patterns of hydrophobic drugs.

[Evaluation of Radiation Dose during Stent-graft Treatment Using a Hybrid Operating Room System].

PubMed

Haga, Yoshihiro; Chida, Kouichi; Kaga, Yuji; Saitou, Kazuhisa; Arai, Takeshi; Suzuki, Shinichi; Iwaya, Yoshimi; Kumasaka, Eriko; Kataoka, Nozomi; Satou, Naoto; Abe, Mitsuya

2015-12-01

In recent years, aortic aneurysm treatment with stent graft grafting in the X-ray fluoroscopy is increasing. This is an endovascular therapy, because it is a treatment which includes the risk of radiation damage, having to deal with radiation damage, to know in advance is important. In this study, in order to grasp the trend of exposure stent graft implantation in a hybrid operating room (OR) system, focusing on clinical data (entrance skin dose and fluoroscopy time), was to count the total. In TEVAR and EVAR, fluoroscopy time became 13.40 ± 7.27 minutes, 23.67 ± 11.76 minutes, ESD became 0.87 ± 0.41 mGy, 1.11 ± 0.57 mGy. (fluoroscopy time of EVAR was 2.0 times than TEVAR. DAP of EVAR was 1.2 times than TEVAR.) When using the device, adapted lesions and usage are different. This means that care changes in exposure-related factors. In this study, exposure trends of the stent graft implantation was able to grasp. It can be a helpful way to reduce/optimize the radiation dose in a hybrid OR system.

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).

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.

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.

Use of biliary stent in laparoscopic common bile duct exploration.

PubMed

Lyon, Matthew; Menon, Seema; Jain, Abhiney; Kumar, Harish

2015-05-01

It is well supported in the literature that laparoscopic common bile duct exploration (LCBDE) for choledocholithiasis has equal efficacy when compared to ERCP followed by laparoscopic cholecystectomy. Decompression after supra-duodenal choledochotomy is common practice as it reduced the risk of bile leaks. We conducted a prospective non-randomized study to compare outcomes and length of stay in patients undergoing biliary stent insertion versus T-tube drainage following LCBDE via choledochotomy. The study involved 116 patients with choledocholithiasis who underwent LCBDE and decompression of the biliary system by either ante-grade biliary stent or T-tube insertion. A 7 French straight/duodenal curve biliary Diagmed™ stent (9-11 cm) was placed in 82 patients (Biliary Stent Group). T-tube insertion was used for 34 patients (T-tube group). The length of hospital stay and complications for the selected patients were recorded. All trans-cystic common bile duct explorations were excluded from the study. The mean hospital stay for patients who underwent ante-grade biliary stent or T-tube insertion after LBCDE were 1 and 3.4 days, respectively. This is a statistically significant result with a p value of less than 0.001. Of the T-tube group, two patients required laparoscopic washout due to bile leaks, one had ongoing biliary stasis and one reported ongoing pain whilst the T-tube was in situ. A complication rate of 11.2%, this was a significant finding. There were no complications or concerns reported for the Biliary Stent Group. Our results show that there is a significant reduction in length of hospital stay and morbidity for patients that have ante-grade biliary stent decompression of the CBD post laparoscopic choledochotomy when compared T-tube drainage. This implies that ante-grade biliary stent insertion is likely to reduce costs and increase overall patient satisfaction. We support the use of ante-grade biliary stent insertion during LCBDE when primary closure is not preferred.

Analysis of artery blood flow before and after angioplasty

NASA Astrophysics Data System (ADS)

Tomaszewski, Michał; Baranowski, Paweł; Małachowski, Jerzy; Damaziak, Krzysztof; Bukała, Jakub

2018-01-01

The study presents a comparison of results obtained from numerical simulations of blood flow in two different arteries. One of them was considered to be narrowed in order to simulate an arteriosclerosis obstructing the blood flow in the vessel, whereas the second simulates the vessel after angioplasty treatment. During the treatment, a biodegradable stent is inserted into the artery, which prevents the vessel walls from collapsing. The treatment was simulated through the use of numerical simulation using the finite element method. The final mesh geometry obtained from the analysis was exported to the dedicated software in order to create geometry in which a flow domain inside the artery with the stent was created. The flow analysis was conducted in ANSYS Fluent software with non-deformable vessel walls.

Bioresorbable Electronic Stent Integrated with Therapeutic Nanoparticles for Endovascular Diseases.

PubMed

Son, Donghee; Lee, Jongha; Lee, Dong Jun; Ghaffari, Roozbeh; Yun, Sumin; Kim, Seok Joo; Lee, Ji Eun; Cho, Hye Rim; Yoon, Soonho; Yang, Shixuan; Lee, Seunghyun; Qiao, Shutao; Ling, Daishun; Shin, Sanghun; Song, Jun-Kyul; Kim, Jaemin; Kim, Taeho; Lee, Hakyong; Kim, Jonghoon; Soh, Min; Lee, Nohyun; Hwang, Cheol Seong; Nam, Sangwook; Lu, Nanshu; Hyeon, Taeghwan; Choi, Seung Hong; Kim, Dae-Hyeong

2015-06-23

Implantable endovascular devices such as bare metal, drug eluting, and bioresorbable stents have transformed interventional care by providing continuous structural and mechanical support to many peripheral, neural, and coronary arteries affected by blockage. Although effective in achieving immediate restoration of blood flow, the long-term re-endothelialization and inflammation induced by mechanical stents are difficult to diagnose or treat. Here we present nanomaterial designs and integration strategies for the bioresorbable electronic stent with drug-infused functionalized nanoparticles to enable flow sensing, temperature monitoring, data storage, wireless power/data transmission, inflammation suppression, localized drug delivery, and hyperthermia therapy. In vivo and ex vivo animal experiments as well as in vitro cell studies demonstrate the previously unrecognized potential for bioresorbable electronic implants coupled with bioinert therapeutic nanoparticles in the endovascular system.

Outcomes with various drug eluting or bare metal stents in patients with diabetes mellitus: mixed treatment comparison analysis of 22 844 patient years of follow-up from randomised trials

PubMed Central

Kumar, Sunil; Fusaro, Mario; Amoroso, Nicholas; Kirtane, Ajay J; Byrne, Robert A; Williams, David O; Slater, James; Cutlip, Donald E; Feit, Frederick

2012-01-01

Objectives To evaluate the efficacy and safety of currently used drug eluting stents compared with each other and compared with bare metal stents in patients with diabetes. Design Mixed treatment comparison meta-analysis. Data sources and study selection PubMed, Embase, and CENTRAL were searched for randomised clinical trials, until April 2012, of four durable polymer drug eluting stents (sirolimus eluting stents, paclitaxel eluting stents, everolimus eluting stents, and zotarolimus eluting stents) compared with each other or with bare metal stents for the treatment of de novo coronary lesions and enrolling at least 50 patients with diabetes. Primary outcomes Efficacy (target vessel revascularisation) and safety (death, myocardial infarction, stent thrombosis). Results From 42 trials with 22 844 patient years of follow-up, when compared with bare metal stents (reference rate ratio 1) all of the currently used drug eluting stents were associated with a significant reduction in target vessel revascularisation (37% to 69%), though the efficacy varied with the type of stent (everolimus eluting stents∼sirolimus eluting stents>paclitaxel eluting stents∼zotarolimus eluting stent>bare metal stents). There was about an 87% probability that everolimus eluting stents were the most efficacious compared with all others, though there were limited usable data for the zotarolimus eluting Resolute stent in patients with diabetes. Moreover, there was no increased risk of any safety outcome (including very late stent thrombosis) with any drug eluting stents compared with bare metal stents. There was about a 62% probability that the everolimus eluting stent was the safest stent for the outcome of “any” stent thrombosis. Conclusions Among patients with diabetes treated with coronary stents all currently available drug eluting stents were efficacious without compromising safety compared with bare metal stents. There were relative differences among the drug eluting stents, such that the everolimus eluting stent was the most efficacious and safe. PMID:22885395

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 better understand the response to attempted TSF for newly developed stents as well as those currently in use.

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

Ciampi, Juan J., E-mail: juanciampi@hotmail.com; Lanciego, Carlos; Navarro, Sofia

The objective of the present study was to evaluate, in a prospective, single-center study, the effectiveness of the Wilhelm-type stent used in interventional radiology for the management of epiphora. Patients (n = 104; mean age 64 [range 25-88]; 33 male and 71 female) with severe epiphora had the stents inserted (135 stents in 115 eyes) to treat obstruction of the nasolacrimal system. The etiology of the obstruction was idiopathic in 83 cases, chronic dacryocystitis in 31, cases and postsurgical status in 1 case. The overall technical success rate of stent placement was near 94%. Resolution of epiphora was complete inmore » 105 cases and partial in 3 cases. During a mean 13-month follow-up (range 1 week to 28 months), the median duration of primary patency was 11 months, and the percentage of patency at 6 months was 60.8%, at 1 year was 39.6%, and at 2 years was 25%. Stents malfunctioned in 54 cases, and all were easily withdrawn except in 1 case. Of these 27 cases, patency recovered spontaneously in 9 and by way of a second stent in 18. Secondary patency was 50%. Factors presdisposing to lower primary patency are inflammatory etiology and location of the obstruction. The benefit of stent deployment is clear with respect to the resolution of epiphora in candidate patients for percutaneous treatment. Technical and/or design improvements would be welcomed.« less

The use of double lasso, fully covered self-expandable metal stents with new "anchoring flap" system in the treatment of benign biliary diseases.

PubMed

Mangiavillano, B; Manes, G; Baron, T H; Frego, R; Dinelli, M; Radaelli, F; Teruzzi, V; Amato, A; Pallotta, S; Santoro, T; Masci, E

2014-09-01

Many benign biliary diseases (BBD) can be treated with fully covered, self-expandable metal stents (FCSEMS) but stent migration occurs in up to 35.7 %. The aim of this study was to prospectively assess the rate of, safety and effectiveness and stent migration of a new biliary FCSEMS with an anti-migration flap (FCSEMS-AF) in patients with BBD. This was a prospective study from four Italian referral endoscopy centers of 32 consecutive patients (10 females and 22 males; mean age: 60.1 ± 14.8 years; range: 32-84 years) with BBD who were offered endoscopic placement of a FCSEMS-AF as first-line therapy. Were 24 strictures and 8 leaks. Stent placement was technically successful in 32/32 patients (100 %). Immediate clinical improvement was seen in all 32 patients (100 %). One late stent migration occurred (3.3 %). FCSEMS-AF were removed from 30 of the 32 patients (93.7 %) at a mean (± SD) of 124.4 ± 84.2 days (range: 10-386 days) after placement. All patients remained clinically and biochemically well at 1- and 3-month follow-up. One patient (3.3 %) with a post-laparoscopic cholecystectomy stricture developed distal stent migration at 125 days. This new FCSEMS with anti-migration flap seems to be a safe and effective first-line treatment option for patients with BBD.

A novel biliary stent coated with silver nanoparticles prolongs the unobstructed period and survival via anti-bacterial activity

PubMed Central

Yang, Fuchun; Ren, Zhigang; Chai, Qinming; Cui, Guangying; Jiang, Li; Chen, Hanjian; Feng, Zhiying; Chen, Xinhua; Ji, Jian; Zhou, Lin; Wang, Weilin; Zheng, Shusen

2016-01-01

Symptomatic biliary stricture causes life-threatening complications, such as jaundice, recurrent cholangitis and secondary biliary cirrhosis. Fully covered self-expanding metal stents (FCSEMSs) are gaining acceptance for treatments of benign biliary stricture and palliative management of malignant biliary obstructions. However, the high rate of FCSEMS obstruction limits their clinic use. In this study, we developed a novel biliary stent coated with silver nanoparticles (AgNPs) and investigated its efficacy both in vitro and in vivo. We first identified properties of the AgNP complex using ultraviolet detection. The AgNP complex was stable without AgNP agglomeration, and Ag abundance was correspondingly increased with an increased bilayer number. The AgNP biliary stent demonstrated good performance in the spin-assembly method based on topographic observation. The AgNP biliary stent also exhibited a long-term anti-coagulation effect and a slow process of Ag+ release. In vitro anti-bacteria experiments indicated that the AgNP biliary stent exhibited high-efficiency anti-bacterial activity for both short- and long-term periods. Importantly, application of the AgNP biliary stent significantly prolonged the unobstructed period of the biliary system and improved survival in preclinical studies as a result of its anti-microbial activity and decreased granular tissue formation on the surface of the anastomotic biliary, providing a novel and effective treatment strategy for symptomatic biliary strictures. PMID:26883081

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.

'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.

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 mortality compared with cobalt chromium everolimus eluting stents (1.52, 1.02 to 2.22). Overall, among all stent types, the newer generation durable polymer drug eluting stents (zotarolimus eluting stent-Resolute, cobalt chromium everolimus eluting stents, and platinum chromium everolimus eluting stents) were the most efficacious (lowest target vessel revascularization rate) stents, and cobalt chromium everolimus eluting stents were the safest with significant reductions in definite stent thrombosis (rate ratio 0.35, 0.21 to 0.53), myocardial infarction (0.65, 0.55 to 0.75), and death (0.72, 0.58 to 0.90) compared with bare metal stents. Conclusions Biodegradable polymer drug eluting stents are superior to first generation durable polymer drug eluting stents but not to newer generation durable polymer stents in reducing target vessel revascularization. Newer generation durable polymer stents, and especially cobalt chromium everolimus eluting stents, have the best combination of efficacy and safety. The utility of biodegradable polymer stents in the context of excellent clinical outcomes with newer generation durable polymer stents needs to be proven. PMID:24212107

Outcomes of second self-expandable metallic stent insertion for malignant gastric outlet obstruction.

PubMed

Kim, Chan Gyoo; Choi, Il Ju; Lee, Jong Yeul; Cho, Soo-Jeong; Kim, Soo Jin; Kim, Mi-Jung; Park, Sook Ryun; Park, Young Lee

2014-01-01

Self-expandable metallic stents are used widely to relieve malignant gastric outlet obstruction (GOO). However, restenosis or migration of first stents is a frequent complication. The purpose of this retrospective cohort study was to evaluate the effectiveness of second stents as an approach to manage failure of first stents in patients with malignant GOO. A total of 222 patients with gastric cancer received first stents due to inoperable GOO at National Cancer Center in Korea between January 2008 and June 2011. Monthly follow-up interviews were performed, and second stents (stent-in-stent or stent-after-migration) were inserted in 59 patients by June 2012. Technical and clinical successes and long-term complications were evaluated. The technical and immediate clinical success rates were 98.3 % (58/59) and 91.5 % (54/59), respectively. Patients who received a second stent due to late complications involving the first stent (migration, restenosis, and fracture) showed a higher clinical success rate (95.8 % [46/48]) than patients who received a second stent due to immediate clinical failure of the first stent (72.7 % [8/11], p = 0.04). The immediate clinical success rate of stent-after-migration (100 % [11/11]) was not different from that of stent-in-stent (89.6 % [43/48], p = 1.0). The stent dysfunction rate of stent-after-migration (27.3 % [3/11]) also was similar to that of stent-in-stent (29.2 % [14/48], p = 1.0). The median patencies of stent-in-stent and stent-after-migration were 27.4 and 58.4 weeks, respectively (p = 0.177). There were no significant prognostic factors for patency of second stents. Insertion of a second stent is effective for treating the first-stent failure in gastric cancer patients with GOO, especially if the immediate outcome of the first stent was successful.

The SPIRIT V study: a clinical evaluation of the XIENCE V everolimus-eluting coronary stent system in the treatment of patients with de novo coronary artery lesions.

PubMed

Grube, Eberhard; Chevalier, Bernard; Smits, Peter; Džavík, Vladimir; Patel, Tejas M; Mullasari, Ajit S; Wöhrle, Jochen; Stuteville, Marrianne; Dorange, Cécile; Kaul, Upendra

2011-02-01

The SPIRIT V (A Clinical Evaluation of the XIENCE V Everolimus-Eluting Coronary Stent System in the Treatment of Patients With De Novo Coronary Artery Lesions) study is a post-market surveillance experience of the XIENCE V (Abbott Vascular, Santa Clara, California) everolimus-eluting stent (EES) in patients with higher-risk coronary anatomy. Previous pre-approval studies have shown the safety and efficacy of EES in highly selected groups of patients. The SPIRIT V trial is a prospective, open label, single arm, multicenter study. Two thousand seven hundred patients with multiple de novo coronary artery lesions suitable for treatment with a planned maximum of 4 EES were enrolled at 93 centers in Europe, Asia Pacific, Canada, and South Africa. Lesions had a reference vessel diameter between 2.25 and 4.0 mm and a length of ≤ 28 mm by visual estimation. An independent clinical events committee adjudicated all end point-related events. The primary end point was the composite rate of all death, myocardial infarction (MI), and target vessel revascularization at 30 days. Secondary end points included stent thrombosis and acute success (clinical device and procedure success). At 30 days, the primary composite end point of all death, MI, and target vessel revascularization was 2.7%. At 1 year, rates of cardiac death, overall MI, and target lesion revascularization were 1.1%, 3.5%, and 1.8%, respectively. The cumulative rate of definite and probable stent thrombosis was low at 0.66% at 1 year. Use of EES in patients with multiple, complex de novo lesions yielded 1-year major adverse cardiac events, stent thrombosis, and target lesion revascularization rates that are comparable to those of the more controlled SPIRIT II and SPIRIT III trials-which included patients with restricted inclusion/exclusion criteria-and other all-comer population, physician-initiated studies like the X-SEARCH (Xience Stent Evaluated At Rotterdam Cardiology Hospital) and COMPARE (A Randomized Controlled Trial of Everolimus-eluting Stents and Paclitaxel-eluting Stents for Coronary Revascularization in Daily Practice) trials. Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Classification and outcomes of extended arch repair for acute Type A aortic dissection: a systematic review and meta-analysis.

PubMed

Smith, Holly N; Boodhwani, Munir; Ouzounian, Maral; Saczkowski, Richard; Gregory, Alexander J; Herget, Eric J; Appoo, Jehangir J

2017-03-01

Distal extent of repair in patients undergoing surgery for acute Type A aortic dissection (ATAAD) is controversial. Emerging hybrid techniques involving open and endovascular surgery have been reported in small numbers by select individual centres. A systematic review and meta-analysis was performed to investigate the outcomes following extended arch repair for ATAAD. A classification system is proposed of the different techniques to facilitate discussion and further investigation. Using Ovid MEDLINE, 38 studies were identified reporting outcomes for 2140 patients. Studies were categorized into four groups on the basis of extent of surgical aortic resection and the method of descending thoracic aortic stent graft deployment; during circulatory arrest (frozen stented elephant trunk) or with normothermic perfusion and use of fluoroscopy (warm stent graft): (I) surgical total arch replacement, (II) total arch and frozen stented elephant trunk, (III) hemiarch and frozen stented elephant trunk and (IV) total arch and warm stent graft. Perioperative event rates were obtained for each of the four groups and the entire cohort using pooled summary estimates. Linearized rates of late mortality and reoperation were calculated. Overall pooled hospital mortality for extended arch techniques was 8.6% (95% CI 7.2-10.0). Pooled data categorized by surgical technique resulted in hospital mortality of 11.9% for total arch, 8.6% total arch and frozen stented elephant trunk, 6.3% hemiarch and frozen stented elephant trunk and 5.5% total arch and 'warm stent graft'. Overall incidence of stroke for the entire cohort was 5.7% (95% CI 3.6-8.2). Rate of spinal cord ischaemia was 2.0% (95% CI 1.2-3.0). Pooled linearized rate of late mortality was 1.66%/pt-yr (95% CI 1.34-2.07) with linearized rate of re-operation of 1.62%/pt-yr (95% CI 1.24-2.05). Perioperative results of extended arch procedures are encouraging. Further follow-up is required to see if long-term complications are reduced with these emerging techniques. The proposed classification system will facilitate future comparison of short- and long-term results of different techniques of extended arch repair for ATAAD. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Relation between calcium burden, echocardiographic stent frame eccentricity and paravalvular leakage after corevalve transcatheter aortic valve implantation.

PubMed

Di Martino, Luigi F M; Soliman, Osama I I; van Gils, Lennart; Vletter, Wim B; Van Mieghem, Nicolas M; Ren, Ben; Galema, Tjebbe W; Schultz, Carl; de Jaegere, Peter P T; Di Biase, Matteo; Geleijnse, Marcel L

2017-06-01

Paravalvular aortic leakage (PVL) after transcatheter aortic valve implantation (TAVI) is a complication with potentially severe consequences. The relation between native aortic root calcium burden, stent frame eccentricity and PVL was not studied before. Two-hundred-and-twenty-three consecutive patients with severe aortic stenosis who underwent TAVI with a Medtronic CoreValve System© and who had available pre-discharge transthoracic echocardiography were studied. Echocardiographic stent inflow frame eccentricity was defined as major-minor diameter in a short-axis view >2 mm. PVL was scored according to the updated Valve Academic Research Consortium (VARC-2) recommendations. In a subgroup of 162 (73%) patients, the calcium Agatston score was available. Stent frame eccentricity was seen in 77 (35%) of patients. The correlation between the Agatston score and stent frame eccentricity was significant (ρ = 0.241, P = 0.003). Paravalvular leakage was absent in 91 cases (41%), mild in 67 (30%), moderate in 51 (23%), and severe in 14 (6%) cases. The correlation between stent frame eccentricity and PVL severity was significant (ρ = 0.525, P < 0.0001). There was a relation between particular eccentric stent frame shapes and the site of PVL. Calcification of the aortic annulus is associated with a subsequent eccentric shape of the CoreValve prosthesis. This eccentric shape results in more PVL, with the localization of PVL related to the shape of stent frame eccentricity. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

Is pre-shock wave lithotripsy stenting necessary for ureteral stones with moderate or severe hydronephrosis?

PubMed

El-Assmy, Ahmed; El-Nahas, Ahmed R; Sheir, Khaled Z

2006-11-01

We performed a prospective, randomized clinical trial to evaluate the outcome of ureteral stents for solitary ureteral stones 2 cm or less in moderately or severely obstructed systems using shock wave lithotripsy. Between 2001 and 2004, 186 patients who met study criteria were randomized into 2 groups. Group 1 received a pre-shock wave lithotripsy 6Fr Double-J stent and group 2 had no stent. Patients were treated with a Dornier MFL 5000 lithotripter. Results were compared in terms of clearance rates, number of shock waves and sessions, irritative voiding symptoms, incidence of complications and secondary interventions. Failure was defined as the need for additional procedure(s) for stone extraction. Overall 164 patients (88.2%) became stone-free after shock wave lithotripsy. Complete stone fragmentation was achieved after 1 to 3 and more than 3 session in 108 (58.1%), 30 (16.1%), 13 (7%) and 14 patients (7.5%), respectively. Ureteral stent insertion did not affect the stone-free rate, which was 84.9% and 91.4% in groups 1 and 2, respectively (p = 0.25). There was no statistical difference in the re-treatment rate, flank pain or temperature in the 2 groups. However, all patients in the stented group significantly complained of side effects attributable to the stent, including dysuria, suprapubic pain, hematuria, pyuria and positive urinary culture. Pretreatment stenting provides no advantage over in situ shock wave lithotripsy for significantly obstructing ureteral calculi. Shock wave lithotripsy is reasonable initial therapy for ureteral stones 2 cm or less that cause moderate or severe hydronephrosis.

Concurrent Angioplasty Balloon Placement for Stent Delivery through Jugular Venous Bulb for Treating Cerebral Venous Sinus Stenosis. Technical Report.

PubMed

Qureshi, Adnan I; Khan, Asif A; Capistrant, Rachel; Qureshi, Mushtaq H; Xie, Kevin; Suri, M Fareed K

2016-10-01

To report upon technique of concurrent placement of angioplasty balloon at the internal jugular vein and sigmoid venous sinus junction to facilitate stent delivery in two patients in whom stent delivery past the jugular bulb was not possible. A 21-year-old woman and a 41-year-old woman with worsening headaches, visual obscuration or diplopia were treated for pseudotumor cerebri associated with transverse venous stenosis. Both patients had undergone primary angioplasty, which resulted in improvement in clinical symptoms followed by the recurrence of symptoms with restenosis at the site of angioplasty. After multiple attempts at stent delivery through jugular venous bulb were unsuccessful, a second guide catheter was placed in the ipsilateral internal jugular vein through contralateral femoral venous approach. A 6 mm × 20 mm (left) or 5 × 15 mm (right) angioplasty balloon was placed across the internal jugular vein and sigmoid sinus junction and partially inflated until the inflation and relative straightening of the junction was observed. In both patients, the internal jugular vein and sigmoid sinus junction was successfully traversed by the stent delivery system in a parallel alignment to inflated balloon. Balloon mounted stent was deployed at the site of restenosis with near complete resolution of lumen narrowing delivery and improvement in clinical symptoms. We report a technique for realignment and diameter change with concurrent placement and partial inflation of angioplasty balloon at the jugular venous bulb to facilitate stent delivery into the sigmoid and transverse venous sinuses in circumstances where multiple attempts at stent delivery are unsuccessful.

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, causing blockage of the inner cavity. In conclusion, the use of a metal and fiber composite in the construction of a knitted stent ensures an expansion performance comparable to that of metallic stents, while providing better kink resistance.« less

A comparison of outcomes between a lumen-apposing metal stent with electrocautery-enhanced delivery system and a bi-flanged metal stent for drainage of walled-off pancreatic necrosis.

PubMed

Bekkali, Noor L H; Nayar, Manu K; Leeds, John S; Charnley, Richard M; Huggett, Matthew T; Oppong, Kofi W

2017-12-01

 Bi-flanged metal stents (BFMS) have shown promise in the drainage of walled-off pancreatic necrosis (WON), but their placement requires multiple steps and the use of other devices. More recently, a novel device consisting of a combined lumen-apposing metal stent (LAMS) and electrocautery-enhanced delivery system has been introduced. The aim of this study was to compare the placement and outcomes of the two devices.  This was a retrospective review of consecutive patients undergoing endoscopic ultrasound-guided placement of BFMS or LAMS for drainage of symptomatic WON. Data from procedures between October 2012 and December 2016 were taken from a prospectively maintained database. We compared technical and clinical success, procedure time, costs, and composite end point of significant events (adverse events, stent migration, additional percutaneous drainage) between BFMS and LAMS.  72 consecutive patients underwent placement of BFMS (40 patients, 44 stents) or LAMS (32 patients, 33 stents). Technical success was 91 % for BFMS and 97 % for LAMS. Clinical success was 65 % vs. 78 %, respectively. Median in-room procedure time was significantly shorter in the LAMS group (45 minutes [range 30 - 80]) than in the BFMS group (62.5 minutes [range 35 - 135]; P  < 0.001) and fewer direct endoscopic necrosectomies (DEN) were performed (median 1 [0 - 2.0] vs. 2 [0 - 3.7], respectively; P  = 0.005). If only inpatients were considered (35 BFMS and 19 LAMS), there was no significant difference in DEN 2 (range 0 - 11) and 2 (range 0 - 8), respectively. The composite end point of 32 % vs. 24 % was not significantly different. Median procedural costs for all patients with successful stent placement for WON treatment was €4427 (range 1630 - 12 926) for BFMS vs. €3500 (range 2509 - 13 393) for LAMS ( P  = 0.10).  LAMS was superior to BFMS in terms of procedure time, with comparable adverse events, success, and costs.

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.

Unconstrained Recovery Characterization of Shape-Memory Polymer Networks for Cardiovascular Applications

PubMed Central

Yakacki, Christopher M.; Shandas, Robin; Lanning, Craig; Rech, Bryan; Eckstein, Alex; Gall, Ken

2009-01-01

Shape-memory materials have been proposed in biomedical device design due to their ability to facilitate minimally invasive surgery and recover to a predetermined shape in-vivo. Use of the shape-memory effect in polymers is proposed for cardiovascular stent interventions to reduce the catheter size for delivery and offer highly controlled and tailored deployment at body temperature. Shape-memory polymer networks were synthesized via photopolymerization of tert-butyl acrylate and poly (ethylene glycol) dimethacrylate to provide precise control over the thermomechanical response of the system. The free recovery response of the polymer stents at body temperature was studied as a function of glass transition temperature (Tg), crosslink density, geometrical perforation, and deformation temperature, all of which can be independently controlled. Room temperature storage of the stents was shown to be highly dependent on Tg and crosslink density. The pressurized response of the stents is also demonstrated to depend on crosslink density. This polymer system exhibits a wide range of shape-memory and thermomechanical responses to adapt and meet specific needs of minimally invasive cardiovascular devices. PMID:17296222

Bench-top Comparison of Physical Properties of 4 Commercially-Available Self-Expanding Intracranial Stents

PubMed Central

Cho, Su-hee; Jo, Won-il; Jo, Ye-eun; Yang, Ku Hyun; Park, Jung Cheol

2017-01-01

Purpose To better understand the performance of four commercially available neurovascular stents in intracranial aneurysm embolization, the stents were compared in terms of their basic morphological and mechanical properties. Materials and Methods Four different types of stents that are currently being used for cerebral aneurysm embolization were prepared (two stents per type). Two were laser-cut stents (Neuroform and Enterprise) and two were braided from a single nitinol wire (LEO and LVIS stents). All were subjected to quantitative measurements of stent size, pore density, metal coverage, the force needed to load, push, and deploy the stent, radial force on deployment, surface roughness, and corrosion resistance. Results Compared to their nominal diameters, all stents had greater diameters after deployment. The length generally decreased after deployment. This was particularly marked in the braided stents. The braided stents also had higher pore densities than the laser-cut stents. Metal coverage was highest in the LEO stent (14%) and lowest in the Enterprise stent (5%). The LIVS stent had the highest microcatheter loading force (81.5 gf). The LEO stent had the highest passage force (55.0 gf) and deployment force (78.9 gf). The LVIS and LEO stents had the highest perpendicular (37.1 gf) and circumferential (178.4 gf) radial forces, respectively. The Enterprise stent had the roughest stent wire, followed by the LVIS, LEO, and Neuroform stents. Conclusion The four neurovascular stent types differed in terms of morphological and physical characteristics. An understanding of this diversity may help to decide which stent is most suitable for specific clinical situations. PMID:28316867

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

Fabrication of cylindrical micro-parts using synchronous rotary scan-projection lithography and chemical etching

NASA Astrophysics Data System (ADS)

Ito, Kaiki; Suzuki, Yuta; Horiuchi, Toshiyuki

2017-07-01

Lithographical patterning on the surface of a fine pipe with a thin wall is required for fabricating three-dimensional micro-parts. For this reason, a new exposure system for printing patterns on a cylindrical pipe by synchronous rotary scan-projection exposure was developed. Using the exposure system, stent-like resist patterns with a width of 251 μm were printed on a surface of stainless-steel pipe with an outer diameter of 2 mm. The exposure time was 30 s. Next, the patterned pipe was chemically etched. As a result, a stent-like mesh pipe with a line width of 230 μm was fabricated. It was demonstrated that the new method had a potential to be applied to fabrications of stent and other cylindrical micro-parts.

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

PubMed Central

Chow, Po-Ming; Chiang, I-Ni; Chen, Chia-Yen; Huang, Kuo-How; Hsu, Jui-Shan; Wang, Shuo-Meng; Lee, Yuan-Ju; Yu, Hong-Jeng; Pu, Yeong-Shiau; Huang, Chao-Yuan

2015-01-01

Background Ureteral obstruction caused by extrinsic compression is often associated with intra-abdominal cancers. Internal drainage with ureteral stents is typically the first-line therapy to relieve such obstructions. Novel designs of ureteral stents made of different materials have been invented to achieve better drainage. In this study, we described the functional outcomes of a Resonance metallic ureteral stent (Cook Medical, Bloomington, Indiana, USA) in patients with malignant ureteral obstruction and compare the functional duration of Resonance stents with regular polymeric stents in the same cohort. Methods Cancer patients who received polymeric stents and subsequent Resonance stents for ureteral obstruction between July 2009 and November 2012 were included in a chart review. Stent failure was detected by clinical symptoms, imaging studies, and renal function tests. The functional durations of each stent were calculated, and possible factors affecting stent patency were investigated. Results A total of 50 stents were successfully inserted into 50 ureteral units in 42 patients with malignant ureteral obstruction. There were 7 antegrade stents and 43 retrograde stents. There were no major complications. Stent-related symptoms were similar in both kinds of stents. After polymeric stents were replaced with Resonance metallic stents, hydronephrosis subsided or remained stable in 90% (45/50) of the ureteral units. Serum creatinine decreased or remained stable in 90% (38/42) of these patients. The Resonance stent exhibited a mean increase in functional duration of 4 months compared with the polymeric stents (p<0.0001), and 50% (25/50) of the Resonance stents exhibited a significant increase in functional duration (more than 3 months). Pre-operative serum creatinine < 2 was associated with a substantial increase in stent duration. Conclusions Resonance stents are effective and safe in relieving malignant ureteral obstructions after polymeric stents failure. Resonance stents can provide a longer functional duration than polymeric stents and should be offered as an option for internal drainage. PMID:26267140

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.

The INNOVATION Trial: four-year safety and effectiveness of the INCRAFT® AAA Stent-Graft System for endovascular repair.

PubMed

Pratesi, Giovanni; Pratesi, Carlo; Chiesa, Roberto; Coppi, Gioacchino; Scheinert, Dierk; Brunkwall, Jan S; van der Meulen, Stefaan; Torsello, Giovanni

2017-10-01

This paper reports the 4-year safety and effectiveness of the INCRAFT® AAA Stent-Graft System (Cordis Corp., Milpitas, CA, USA), an ultra-low-profile device for the treatment of abdominal aortic aneurysms. The INNOVATION Trial is the prospective, first-in-human, multicenter trial to evaluate the safety and effectiveness of the INCRAFT® System. Patients underwent annual clinical and computed tomography angiography examination as part of the study protocol. The INCRAFT® AAA Stent-Graft System is a customizable tri-modular design, with an ultra-low profile (14-Fr) delivery system. Patient were treated under approved protocol, the prescribed clinical and imaging follow-up at annually through 5 years. Results analyzed and adjudicated by a clinical events committee, independent core laboratory, and a data safety and monitoring board. This manuscript reports results through 4 years of follow-up. A total of 60 patients were enrolled in the trial, all of whom were successfully treated. Follow-up rates at 1 and 4 years were 93% (56/60) and 85% (51/60), respectively. All-cause mortality at 4 years was 17.6% and no death was AAA-, device-, or procedure-related. The secondary reintervention rate at 1 year was 4.6%, primarily the result of stent thrombosis. In total, 10 patients required 13 post-procedure interventions within 4-years of follow-up (2 to repair a type I endoleak, 4 to repair a type II endoleak, 1 for stent thrombosis, 1 for renal stenosis, 1 for aneurysm enlargement, 2 for limb migration and 2 for prosthesis stenosis or occlusion). There were 4 cases (10%) of aneurysm enlargement reported at the 4 year follow-up. At 4 years, 38 out of 39 patients were free from type I and III endoleaks. There were no proximal type I or type III endoleaks at 4-year follow-up. Core laboratory evaluation of the postoperative imaging studies indicated absence of endograft migration while a single fracture was demonstrated without any clinical sequelae. The INCRAFT® AAA Stent-Graft System provides a minimally invasive and durable solution for patients undergoing EVAR that has been associated with a low frequency of device-related events through 4 years of follow-up.

Financial impact of coronary stenting in emergency for acute coronary syndromes.

PubMed

Nidegger, Delphine; Metz, Damien; Vacter, Christophe; Tassan-Mangina, Sophie; Deschildre, Alain; Gawron, Michel; Bourgeois, Jacqueline

2009-05-01

Since the prospective payment system, health institutions have only specific payments for the emergency care in the emergency room. The direct urgent admissions in coronary care units for acute coronary syndrome (ACS) do not collect this complementary refund. For the patient's stay, hospital is remunerated with fixed national prices which are similar even in case of emergent or planed coronary revascularization when realized. To analyze and compare the financial impact between emergent and planed coronary stenting in the setting of ACS. This retrospective study was based on patients suffering from ACS who experienced emergent coronary stenting during the year 2005. On 154 patients, 127 were age-, sex- and diagnosis-related group (called "groupe homogène de malades" in the French Health Care system)-matched with 127 suffering from same ACS but with planed "ad hoc" coronary stenting. The overall charges (medical and paramedical team, pharmacy, biology, implantable coronary devices, radiology) were compared between the two groups. Mean stay duration was 6.7 days and did not differ between the two groups. Mean financial retributions were significantly higher in the emergent group (7338 euro [6831-7846] IC95 vs 6509 euro [5994-7023]; p=0,02) but with a much more raised consumption (6810 euro [6283-7336] vs 5223 euro [4632-5814]; p=0,001). This overcost was due especially to drugs and biological expenses. The hospitalization payments did not cover the overall expenses for 25% of the patients' stays (N=64) among whom 39 have had emergent coronary stenting (30.7%, p=0.04). Among the different GHM, the most important difference was observed in non-STEMI without complication with a negative receipts/costs ratio for 37.8% of the stay with coronary stenting in emergency. The application of the recent guidelines for coronary revascularization in the management of ACS represents a financial venture for hospital institutions. The engaged charges for emergent coronary stenting are covered with difficulties contrary to planed revascularization.

Direct comparison of coronary bare metal vs. drug-eluting stents: same platform, different mechanics?

PubMed

Schmidt, Wolfram; Lanzer, Peter; Behrens, Peter; Brandt-Wunderlich, Christoph; Öner, Alper; Ince, Hüseyin; Schmitz, Klaus-Peter; Grabow, Niels

2018-01-08

Drug-eluting stents (DES) compared to bare metal stents (BMS) have shown superior clinical performance, but are considered less suitable in complex cases. Most studies do not distinguish between DES and BMS with respect to their mechanical performance. The objective was to obtain mechanical parameters for direct comparison of BMS and DES. In vitro bench tests evaluated crimped stent profiles, crossability in stenosis models, elastic recoil, bending stiffness (crimped and expanded), and scaffolding properties. The study included five pairs of BMS and DES each with the same stent platforms (all n = 5; PRO-Kinetic Energy, Orsiro: BIOTRONIK AG, Bülach, Switzerland; MULTI-LINK 8, XIENCE Xpedition: Abbott Vascular, Temecula, CA; REBEL Monorail, Promus PREMIER, Boston Scientific, Marlborough, MA; Integrity, Resolute Integrity, Medtronic, Minneapolis, MN; Kaname, Ultimaster: Terumo Corporation, Tokyo, Japan). Statistical analysis used pooled variance t tests for pairwise comparison of BMS with DES. Crimped profiles in BMS groups ranged from 0.97 ± 0.01 mm (PRO-Kinetic Energy) to 1.13 ± 0.01 mm (Kaname) and in DES groups from 1.02 ± 0.01 mm (Orsiro) to 1.13 ± 0.01 mm (Ultimaster). Crossability was best for low profile stent systems. Elastic recoil ranged from 4.07 ± 0.22% (Orsiro) to 5.87 ± 0.54% (REBEL Monorail) including both BMS and DES. The bending stiffness of crimped and expanded stents showed no systematic differences between BMS and DES neither did the scaffolding. Based on in vitro measurements BMS appear superior to DES in some aspects of mechanical performance, yet the differences are small and not class uniform. The data provide assistance in selecting the optimal system for treatment and assessment of new generations of bioresorbable scaffolds. not applicable.

Comparative Case-Control analysis of a dedicated self-expanding Biolimus A9-eluting Bifurcation stent versus provisional or mandatory side branch intervention strategies in the treatment of coronary bifurcation lesions.

PubMed

Ohlow, Marc-Alexander; Farah, Ahmed; Richter, Stefan; El-Garhy, Mohamad; von Korn, Hubertus; Lauer, Bernward

2017-07-01

In a number of coronary bifurcation lesions, both the main vessel and the side branch (SB) need stent coverage. To analyze the procedural performance and the impact on radiation times (RT) and contrast medium consumption (CMC) of the Axxess™ stent system (Biosensors, Switzerland) treating de novo bifurcation lesions (DBL). One hundred and ten consecutive prospectively enrolled cases (Axxess Group) and 110 age, sex, and lesion location matched controls undergoing mandatory (Group A, n = 56) or provisional (Group B, n = 54) SB intervention were analyzed. Although more pre-dilatation was performed in the Axxess Group (92.7% vs. 46.4% [Group A] vs. 24.1% [Group B]), and more stents were used (2.4 vs. 1.2 vs. 1.05), RT and CMC were significantly lower in the Axxess Group [7.9 min/129 ml vs. 14.2 min/209 ml vs. 7.8 min/152 ml; P < 0.001]. Final Thrombolysis In Myocardial Infarction three flow in both branches was significantly more frequent in the Axxess Group (98.2% vs. 94.6% vs. 88.9%; P = 0.02), and post-interventional troponin T elevations were the lowest in the Axxess Group. Eighty one percent of the Axxess-stents could be implanted without technical difficulties. Difficult implantations procedures were mainly related to coronary anatomy. There was no safety concerns (cardiac death, stent-thrombosis) compared to controls. Cumulative 6-months MACE rates were 11% versus 23% versus 25%. TLR rates at 6-months were 5%, 18%, and 15%, respectively. Axxess bifurcation stent system procedures were associated with significantly less RT and CMC compared to conventional DBL therapy strategies. Difficult coronary anatomy may hinder successful implantation and a learning curve has to be considered. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Effect of Antithrombotic Agents on the Patency of PTFE-Covered Stents in the Inferior Vena Cava: An Experimental Study

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

Makutani, Shiro; Kichikawa, Kimihiko; Uchida, Hideo

Purpose: To evaluate the efficacy of antithrombotic agents in the prevention of stenosis of polytetrafluoroethylene (PTFE)-covered stents in the venous system. Methods: Spiral Z stents covered with PTFE (PTFE-covered stents) were placed in the inferior vena cava (IVC) of 34 dogs. Nineteen dogs, used as a control group, were sacrificed at 2, 4, and 12 weeks. Fifteen dogs, previously given antithrombotic agents [cilostazol (n= 5), warfarin potassium (n= 5), cilostazol plus warfarin potassium (n= 5)] were sacrificed at 4 weeks, and then examined angiographically and histopathologically. The effect of the antithrombotic agents was compared between groups. Results: The patency ratemore » of the antithrombotic agent group was 93% (14/15), which was higher than the control group rate of 63% (12/19). The mean stenosis rate of the patent stent at both ends and at the midportion was lower at 4 weeks in the antithrombotic agent group than in the control group. In particular, the mean stenosis rate in the cilostazol plus warfarin potassium group was significantly lower than the control group (Tukey's test, p < 0.05). The mean neointimal thickness of the patent stent at both ends and at the midportion was thinner at 4 weeks in the antithrombotic agent group than in the control group. In particular, the thickness of the neointima in the cilostazol plus warfarin potassium group was significantly decreased when compared with the control group (Tukey's test p < 0.05). At 4 weeks, endothelialization in the antithrombotic agent group tended to be almost identical to that in the control group. Conclusion: The present study suggests that administration of an antithrombotic agent is an effective way of preventing the stenosis induced by a neointimal thickening of PTFE-covered stents in the venous system.« less

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

Economic impact of angioplasty salvage techniques, with an emphasis on coronary stents: a method incorporating costs, revenues, clinical effectiveness and payer mix.

PubMed

Vaitkus, P T; Witmer, W T; Brandenburg, R G; Wells, S K; Zehnacker, J B

1997-10-01

We sought to broaden assessment of the economic impact of percutaneous transluminal coronary angioplasty (PTCA) revascularization salvage strategies by taking into account costs, revenues, the off-setting effects of prevented clinical complications and the effects of payer mix. Previous economic analyses of PTCA have focused on the direct costs of treatment but have not accounted either for associated revenues or for the ability of costly salvage techniques such as coronary stenting to reduce even costlier complications. Procedural costs, revenues and contribution margins (i.e., "profit") were measured for 765 consecutive PTCA cases to assess the economic impact of salvage techniques (prolonged heparin administration, thrombolysis, intracoronary stenting or use of perfusion balloon catheters) and clinical complications (myocardial infarction, coronary artery bypass graft surgery [CABG] or acute vessel closure with repeat PTCA). To assess the economic impact of various salvage techniques for failed PTCA, we used actual 1995 financial data as well as models of various mixes of fee-for-service, diagnosis-related group (DRG) and capitated payers. Under fee-for-service arrangements, most salvage techniques were profitable for the hospital. Stents were profitable at almost any level of clinical effectiveness. Under DRG-based systems, most salvage techniques such as stenting produced a financial loss to the hospital because one complication (CABG) remained profitable. Under capitated arrangements, stenting and other salvage modalities were profitable only if they were clinically effective in preventing complications in > 50% of cases in which they were used. The economic impact of PTCA salvage techniques depends on their clinical effectiveness, costs and revenues. In reimbursement systems dominated by DRG payers, salvage techniques are not rewarded, whereas complications are. Under capitated systems, the level of clinical effectiveness needed to achieve cost savings is probably not achievable in current practice. Further studies are needed to define equitable reimbursement schedules that will promote clinically effective practice.

Magnetic navigation for thoracic aortic stent-graft deployment using ultrasound image guidance.

PubMed

Luo, Zhe; Cai, Junfeng; Wang, Su; Zhao, Qiang; Peters, Terry M; Gu, Lixu

2013-03-01

We propose a system for thoracic aortic stent-graft deployment that employs a magnetic tracking system (MTS) and intraoperative ultrasound (US). A preoperative plan is first performed using a general public utilities-accelerated cardiac modeling method to determine the target position of the stent-graft. During the surgery, an MTS is employed to track sensors embedded in the catheter, cannula, and the US probe, while a fiducial landmark based registration is used to map the patient's coordinate to the image coordinate. The surgical target is tracked in real time via a calibrated intraoperative US image. Under the guidance of the MTS integrated with the real-time US images, the stent-graft can be deployed to the target position without the use of ionizing radiation. This navigation approach was validated using both phantom and animal studies. In the phantom study, we demonstrate a US calibration accuracy of 1.5 ± 0.47 mm, and a deployment error of 1.4 ± 0.16 mm. In the animal study, we performed experiments on five porcine subjects and recorded fiducial, target, and deployment errors of 2.5 ± 0.32, 4.2 ± 0.78, and 2.43 ± 0.69 mm, respectively. These results demonstrate that delivery and deployment of thoracic stent-graft under MTS-guided navigation using US imaging is feasible and appropriate for clinical application.

Stent placement for benign colonic stenosis: case report, review of the literature, and animal pilot data.

PubMed

Geiger, Timothy M; Miedema, Brent W; Tsereteli, Zurab; Sporn, Emanuel; Thaler, Klaus

2008-10-01

Permanent metal stent placement for malignant intestinal obstruction has been proven to be efficient. Temporary stents for benign conditions of the colon and rectum are less studied. This is a case study, review of the literature, and observation from an animal model on placement of stents in the colorectum for benign disease. A 55-year-old man presented with recurrent obstructions from a benign stricture of the distal sigmoid colon. After failed balloon dilations, a polyester coated stent was placed. The purpose of the stent was to improve symptoms and avoid surgery. The stent was expelled after 5 days. We conducted a literature review of stents placed for benign colorectal strictures and an animal study to evaluate stent migration. In the literature, there were 53 reports of uncovered metal stents, four covered metal stents, and six polyester stents. Patency rates were 71%, and migration rate was 43%. Migration occurred earlier with polyester stents (mean=8 days) versus covered (32 days) or uncovered metal stents (112 days). Severe complications were seen in 23% of patients. Four 45-kg pigs underwent rectosigmoid transection with a 21-mm anastomosis and endoscopic placement of a Polyflex stent. Two stents were secured with suture. Stents without fixation were expelled within 24 h of surgery. Stents with fixation were expelled between postoperative days 2 and 14. Stents for the treatment of benign colorectal strictures are safe, with comparable patency rates between stent types. Metal stents can cause severe complications. In a pig model, covered polyester stents tend to migrate early even with fixation. Further investigation needs to focus on new stent designs and/or better fixation.

The diffusion of medical technology, local conditions, and technology re-invention: a comparative case study on coronary stenting.

PubMed

Hashimoto, Hideki; Noguchi, Haruko; Heidenreich, Paul; Saynina, Olga; Moreland, Abigail; Miyazaki, Shunichi; Ikeda, Shunya; Kaneko, Yoshihiro; Ikegami, Naoki

2006-12-01

Innovation of medical technology is a major driving force behind the increase in medical expenditures in developed countries. Previous studies identified that the diffusion of medical technology varied across countries according to the characteristics of regulatory policy and payment systems. Based on Roger's diffusion of innovation theory, this study purported to see how local practice norms, the evolving nature of diffusing technology, and local clinical needs in addition to differences in politico-economic systems would affect the process of innovation diffusion. Taking a case of coronary stenting, an innovative therapeutic technology in early 1990s, we provided a case study of hospital-based data between two teaching high-tech hospitals in Japan and the US for discussion. Stenting began to be widely used in both countries when complementary new technology modified its clinical efficacy, but the diffusion process still differed between the two hospitals due to (1) distinctive payment systems for hospitals and physicians, (2) practice norms in favor of percutaneous intervention rather than bypass surgery that was shaped by payment incentives and cultural attitudes, and (3) local patient's clinical characteristics that the technology had to be tailored for. The case study described the diffusion of stent technology as a dynamic process between patients, physicians, hospitals, health care systems, and technology under global and local conditions.

Comparative study of CW, nanosecond- and femtosecond-pulsed laser microcutting of AZ31 magnesium alloy stents.

PubMed

Gökhan Demir, Ali; Previtali, Barbara

2014-06-01

Magnesium alloys constitute an interesting solution for cardiovascular stents due to their biocompatibility and biodegradability in human body. Laser microcutting is the industrially accepted method for stent manufacturing. However, the laser-material interaction should be well investigated to control the quality characteristics of the microcutting process that concern the surface roughness, chemical composition, and microstructure of the final device. Despite the recent developments in industrial laser systems, a universal laser source that can be manipulated flexibly in terms of process parameters is far from reality. Therefore, comparative studies are required to demonstrate processing capabilities. In particular, the laser pulse duration is a key factor determining the processing regime. This work approaches the laser microcutting of AZ31 Mg alloy from the perspective of a comparative study to evaluate the machining capabilities in continuous wave (CW), ns- and fs-pulsed regimes. Three industrial grade machining systems were compared to reach a benchmark in machining quality, productivity, and ease of postprocessing. The results confirmed that moving toward the ultrashort pulse domain the machining quality increases, but the need for postprocessing remains. The real advantage of ultrashort pulsed machining was the ease in postprocessing and maintaining geometrical integrity of the stent mesh after chemical etching. Resultantly, the overall production cycle time was shortest for fs-pulsed laser system, despite the fact that CW laser system provided highest cutting speed.

Effect of a Flared Renal Stent on the Performance of Fenestrated Stent-Grafts at Rest and Exercise Conditions.

PubMed

Kandail, Harkamaljot; Hamady, Mohamad; Xu, Xiao Yun

2016-10-01

To quantify the hemodynamic impact of a flared renal stent on the performance of fenestrated stent-grafts (FSGs) by analyzing flow patterns and wall shear stress-derived parameters in flared and nonflared FSGs in different physiologic scenarios. Hypothetical models of FSGs were created with and without flaring of the proximal portion of the renal stent. Flared FSGs with different dilation angles and protrusion lengths were examined, as well as a nonplanar flared FSG to account for lumbar curvature. Laminar and pulsatile blood flow was simulated by numerically solving Navier-Stokes equations. A physiologically realistic flow rate waveform was prescribed at the inlet, while downstream vasculature was modeled using a lumped parameter 3-element windkessel model. No slip boundary conditions were imposed at the FSG walls, which were assumed to be rigid. While resting simulations were performed on all the FSGs, exercise simulations were also performed on a flared FSG to quantify the effect of flaring in different physiologic scenarios. For cycle-averaged inflow of 2.94 L/min (rest) and 4.63 L/min (exercise), 27% of blood flow was channeled into each renal branch at rest and 21% under exercise for all the flared FSGs examined. Although the renal flow waveform was not affected by flaring, flow within the flared FSGs was disturbed. This flow disturbance led to high endothelial cell activation potential (ECAP) values at the renal ostia for all the flared geometries. Reducing the dilation angle or protrusion length and exercise lowered the ECAP values for flared FSGs. Flaring of renal stents has a negligible effect on the time dependence of renal flow rate waveforms and can maintain sufficient renal perfusion at rest and exercise. Local flow patterns are, however, strongly dependent on renal flaring, which creates a local flow disturbance and may increase the thrombogenicity at the renal ostia. Smaller dilation angles, shorter protrusion lengths, and moderate lower limb exercise are likely to reduce the risk of thrombosis in flared geometries. © The Author(s) 2016.

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.

Newly designed plastic stent for endoscopic placement above the sphincter of Oddi in patients with malignant hilar biliary obstruction.

PubMed

Ishiwatari, Hirotoshi; Hayashi, Tsuyoshi; Ono, Michihiro; Sato, Tsutomu; Kato, Junji

2013-05-01

Plastic stent (PS) occlusion occurs as a result of bacterial adherence to the stent's inner wall. To retain the bacteriological barrier, placing a PS above the sphincter of Oddi ('inside stent') has been investigated. We designed a new PS (inside stent with thread [IT] stent) with attachable nylon thread for use as an inside stent and for easy retrieval. The present study evaluated the IT stent's technical feasibility and efficacy for malignant hilar biliary obstruction. A total of 26 consecutive patients with unresectable malignant hilar biliary obstruction underwent placement of IT stents from August 2007 to February 2011. IT stents were placed across the strictures without sphincterotomy to achieve bilateral drainage. The overall technical success rate of the IT stent was 100% for one session. Multiple IT stents were inserted in 25 cases(two stents in 15 patients, three stents in 10 patients). No stent-related early complications occurred. The functional success rate was 92% (24/26). The rate of reintervention because of stent malfunction was 50% (13/26). In all 16 patients who underwent stent removal, IT stents were easily retrieved using the nylon thread. According to Kaplan-Meier analysis, the median stent patency period was 136 days. IT stents for endoscopic placement above the sphincter of Oddi can be used safely and effectively for malignant hilar biliary obstruction. © 2013 The Authors. Digestive Endoscopy © 2013 Japan Gastroenterological Endoscopy Society.

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.

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.

Safety of endoscopic removal of self-expandable stents after treatment of benign esophageal diseases.

PubMed

van Halsema, Emo E; Wong Kee Song, Louis M; Baron, Todd H; Siersema, Peter D; Vleggaar, Frank P; Ginsberg, Gregory G; Shah, Pari M; Fleischer, David E; Ratuapli, Shiva K; Fockens, Paul; Dijkgraaf, Marcel G W; Rando, Giacomo; Repici, Alessandro; van Hooft, Jeanin E

2013-01-01

Temporary placement of self-expandable stents has been increasingly used for the management of benign esophageal diseases. To evaluate the safety of endoscopic removal of esophageal self-expandable stents placed for the treatment of benign esophageal diseases. Multicenter retrospective study. Six tertiary care centers in the United States and Europe. A total of 214 patients with benign esophageal diseases undergoing endoscopic stent removal. Endoscopic stent removal. Endoscopic techniques for stent removal, time to stent removal, and adverse events related to stent removal. A total of 214 patients underwent a total of 329 stent extractions. Stents were mainly placed for refractory strictures (49.2%) and fistulae (49.8%). Of the removed stents, 52% were fully covered self-expandable metal stents (FCSEMSs), 28.6% were partially covered self-expandable metal stents (PCSEMSs), and 19.5% were self-expandable plastic stents. A total of 35 (10.6%) procedure-related adverse events were reported, including 7 (2.1%) major adverse events. Multivariate analysis revealed that use of PCSEMSs (P < .001) was a risk factor for adverse events during stent removal. Favorable factors for successful stent removal were FCSEMSs (P ≤ .012) and stent migration (P = .010). No significant associations were found for stent indwelling time (P = .145) and stent embedding (P = .194). Retrospective analysis, only tertiary care centers. With an acceptable major adverse event rate of 2.1%, esophageal stent removal in the setting of benign disease was found to be a safe and feasible procedure. FCSEMSs were more successfully removed than self-expandable plastic stents and PCSEMSs. Adverse events caused by stent removal were not time dependent. Copyright © 2013 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

In vitro experiments of vessel wall apposition between the Enterprise and Enterprise 2 stents for treatment of cerebral aneurysms.

PubMed

Kono, Kenichi; Terada, Tomoaki

2016-02-01

A closed-cell stent called Enterprise has been used for stent-assisted coil embolization of cerebral aneurysms. The Enterprise stent tends to cause kinks and vessel wall malposition in curved vessels and may cause thromboembolic complications. We evaluated vessel wall apposition of a new closed-cell stent, Enterprise 2, compared with a previous Enterprise stent, using curved vascular silicone models. The Enterprise or Enterprise 2 stent was deployed in curved vascular models with various radii of approximately 5 to 10 mm. Stent deployment was performed 25 times in each stent. A push-pull technique was used to minimize incomplete wall apposition. To evaluate conformity of stents, gaps between a stent and a vessel wall were measured. The gap ratio (gap / a wall diameter) was 15 % ± 17 % (mean ± standard deviation) and 41 % ± 15 % with the Enterprise 2 stent and the Enterprise stent, respectively. Taking gap ratios and radii of vessel curvature into consideration, the Enterprise 2 stent had significantly better wall apposition than the Enterprise stent (p = 0.005). In the same radius of vessel curvature, the Enterprise 2 stent had approximately half of the gap compared with the Enterprise stent. There were no significant differences in vessel straightening effects between the two stents. The Enterprise 2 stent has better wall apposition in curved vessels than the Enterprise stent. The gap between a vessel wall and the Enterprise 2 stent is approximately half that of the Enterprise stent. However, gaps and kinks are still present in curved vessels with a small radius. Caution should be taken for kinks and malposition in acutely curved vessels, such as the siphon of the internal carotid artery.

A newly designed big cup nitinol stent for gastric outlet obstruction

PubMed Central

Shi, Ding; Liao, Sheng-Hui; Geng, Jian-Ping

2010-01-01

AIM: To find out whether a newly designed big cup nitinol stent is suitable for treatment of patients with gastric outlet obstruction resulting from gastric cancer. METHODS: The new stent is composed of a proximal big cup segment (20 mm in length and 48-55 mm in diameter), a middle part (60 mm in length and 20 mm in diameter) covered by a polyethylene membrane and a distal sphericity (20 mm in length and 28 mm in diameter). Half of the proximal big cup segment is also covered by a polyethlene membrane, which is adjacent to the middle part of the stent. The stent is preloaded in a 6.0-mm-diameter introducer system. Thirteen patients with gastric outlet obstruction resulting from gastric cancer received the new stents under endoscopic and fluoroscopic guidance. RESULTS: Technical success was achieved in 12 of 13 (92.3%) patients. Among the 12 patients in whom endoscopic stent was placed successfully, the clinical success rate was 91.7% during a follow-up of average 6.5 mo. During the first month follow-up, the migration rate was 0%, recurrent obstruction 0% and gastric bleeding 8.3%. During the follow-up between 2-12 mo, no migration, recurrent obstruction and gastric bleeding occurred. CONCLUSION: The proximal big cup segment seems to be effective and promising for technical efficacy, clinical outcome, and preventing migration and tumor ingrowth and increasing the emptying rate of sinus ventriculi. PMID:20806440

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

PubMed

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

2015-08-01

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

A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys

PubMed Central

Haider, Waseem; Munroe, Norman; Pulletikurthi, Chandan; Singh Gill, Puneet K.; Amruthaluri, Sushma

2009-01-01

Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry. It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry due to nickel sensitivity experienced by many patients. In recent times, several new Nitinol alloys have been introduced with the addition of a ternary element. Nevertheless, there is still a dearth of information concerning the biocompatibility and corrosion resistance of these alloys. This study compared the biocompatibility of two ternary Nitinol alloys prepared by powder metallurgy (PM) and arc melting (AM) and critically assessed the influence of the ternary element. ASTM F 2129-08 cyclic polarization in vitro corrosion tests were conducted to evaluate the corrosion resistance in phosphate buffered saline (PBS). The growth of endothelial cells on NiTi was examined using optical microscopy. PMID:19956791

A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys

NASA Astrophysics Data System (ADS)

Haider, Waseem; Munroe, Norman; Pulletikurthi, Chandan; Gill, Puneet K. Singh; Amruthaluri, Sushma

2009-08-01

Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry. It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry due to nickel sensitivity experienced by many patients. In recent times, several new Nitinol alloys have been introduced with the addition of a ternary element. Nevertheless, there is still a dearth of information concerning the biocompatibility and corrosion resistance of these alloys. This study compared the biocompatibility of two ternary Nitinol alloys prepared by powder metallurgy (PM) and arc melting (AM) and critically assessed the influence of the ternary element. ASTM F 2129-08 cyclic polarization in vitro corrosion tests were conducted to evaluate the corrosion resistance in phosphate buffered saline (PBS). The growth of endothelial cells on NiTi was examined using optical microscopy.

A Comparative Biocompatibility Analysis of Ternary Nitinol Alloys.

PubMed

Haider, Waseem; Munroe, Norman; Pulletikurthi, Chandan; Singh Gill, Puneet K; Amruthaluri, Sushma

2009-08-01

Nitinol alloys are rapidly being utilized as the material of choice in a variety of applications in the medical industry. It has been used for self-expanding stents, graft support systems, and various other devices for minimally invasive interventional and endoscopic procedures. However, the biocompatibility of this alloy remains a concern to many practitioners in the industry due to nickel sensitivity experienced by many patients. In recent times, several new Nitinol alloys have been introduced with the addition of a ternary element. Nevertheless, there is still a dearth of information concerning the biocompatibility and corrosion resistance of these alloys. This study compared the biocompatibility of two ternary Nitinol alloys prepared by powder metallurgy (PM) and arc melting (AM) and critically assessed the influence of the ternary element. ASTM F 2129-08 cyclic polarization in vitro corrosion tests were conducted to evaluate the corrosion resistance in phosphate buffered saline (PBS). The growth of endothelial cells on NiTi was examined using optical microscopy.

Early outcomes with a single-sided access endovascular stent.

PubMed

Hofmann, Michael; Pecoraro, Felice; Planer, David; Pfammatter, Thomas; Puippe, Gilbert; Bettex, Dominique; Veith, Frank J; Lachat, Mario; Chaykovska, Lyubov

2018-03-27

The objective of this study was to report the 1-year follow-up study results of the new Horizon stent graft (Endospan, Herzliya, Israel) from two different prospective consecutive trials. The Horizon abdominal aortic aneurysm stent graft system is a 14F profile system requiring only a single access site. It consists of three modules, introduced separately: base limb (iliac to iliac limb); distal aortic limb; and proximal aortic limb with a bare suprarenal crown and active fixation. Data from the first in man (FIM) clinical study with 10 patients enrolled and the pivotal study with 30 patients were analyzed. Outcomes measured were freedom from major adverse events (MAEs) including all-cause mortality, myocardial infarction, renal failure, respiratory failure, paraplegia, stroke, bowel ischemia, and procedural blood loss ≥1000 mL. Performance end points included successful delivery and deployment of the device, freedom from aneurysm growth ≥5 mm, type I or type III endoleak, stent graft occlusion, conversion to open surgery, rupture, and stent graft migration. In the FIM study, one conversion to open surgery with >1000 mL of blood loss was registered perioperatively. In the pivotal study, no perioperative MAE was registered. Overall, at 1-year follow-up, two deaths and one aneurysm growth unrelated to endoleak were registered. The results of both the FIM and pivotal studies demonstrated that 39 of 40 procedures were successful for delivery and deployment of the Horizon stent graft. No MAE was registered during the follow-up. The primary safety and performance end points were met in both studies. Copyright © 2018 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

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

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

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.

Endobiliary stent: marker for patient alignment in image-guided radiotherapy in pancreatic and periampullary cancers.

PubMed

Shukla, Pragya; Engineer, Reena; Chopra, Supriya; Shrivastava, Shyam Kishore

2013-12-01

The aim of this study was to analyse the possibility of using stent in pretreatment megavoltage computed tomography (MVCT) images with respect to that on planning kilovoltage computed tomography as tumour surrogate during matching for daily registration in cases of pancreatic and periampullary cancer treated on a TomoTherapy Hi-Art system. Planning CT and pretreatment MVCT of the first and then after every three fractions were transferred to a FocalSim workstation for ten patients. Planning CT of each patient was independently fused with each of the seven MVCT images of that patient. The stent was contoured on all of the eight images for each patient. The difference between the three co-ordinates of centre of mass (CM) of the stent on the planning CT and seven MVCT images was found. The difference between CM of the liver and stents on the planning CT as well as on the MVCT for all seven fractions was also calculated. The mean of these differences across all patients was calculated and analysed. The mean difference in planning and MVCT CMs for stents in the X, Y and Z directions was 0.13 cm (±0.4), 0.16 cm (±2.2) and 0.35 cm (±0.7), respectively. Average difference between CM of the liver and stent on the planning CT in the X, Y and Z directions was found to be 1.832 cm (±1.64), 5.34 cm (±1.33) and 0.54 cm (±0.26), respectively. Average difference between CM of the liver and CM of stent on the MVCT for that day in the X, Y and Z directions was found to be 1.93 cm (±1.5), 4.6 cm (±1.03) and 0.654 cm (±0.35), respectively. Endobiliary stents are stable tumour localisation surrogates and can be used to correct for interfraction target motion.

Quantification of thrombus formation in malapposed coronary stents deployed in vitro through imaging analysis.

PubMed

Brown, Jonathan; O'Brien, Caroline C; Lopes, Augusto C; Kolandaivelu, Kumaran; Edelman, Elazer R

2018-04-11

Stent thrombosis is a major complication of coronary stent and scaffold intervention. While often unanticipated and lethal, its incidence is low making mechanistic examination difficult through clinical investigation alone. Thus, throughout the technological advancement of these devices, experimental models have been indispensable in furthering our understanding of device safety and efficacy. As we refine model systems to gain deeper insight into adverse events, it is equally important that we continue to refine our measurement methods. We used digital signal processing in an established flow loop model to investigate local flow effects due to geometric stent features and ultimately its relationship to thrombus formation. A new metric of clot distribution on each microCT slice termed normalized clot ratio was defined to quantify this distribution. Three under expanded coronary bare-metal stents were run in a flow loop model to induce clotting. Samples were then scanned in a MicroCT machine and digital signal processing methods applied to analyze geometric stent conformation and spatial clot formation. Results indicated that geometric stent features play a significant role in clotting patterns, specifically at a frequency of 0.6225 Hz corresponding to a geometric distance of 1.606 mm. The magnitude-squared coherence between geometric features and clot distribution was greater than 0.4 in all samples. In stents with poor wall apposition, ranging from 0.27 mm to 0.64 mm maximum malapposition (model of real-world heterogeneity), clots were found to have formed in between stent struts rather than directly adjacent to struts. This early work shows how the combination of tools in the areas of image processing and signal analysis can advance the resolution at which we are able to define thrombotic mechanisms in in vitro models, and ultimately, gain further insight into clinical performance. Copyright © 2018 Elsevier Ltd. All rights reserved.

Protection or nonprotection in carotid stent angioplasty: the influence of interventional techniques on outcome data from the SPACE Trial.

PubMed

Jansen, Olav; Fiehler, Jens; Hartmann, Marius; Brückmann, Hartmut

2009-03-01

The use of protection devices (PDs) and stents with different cell designs in carotid artery stenting (CAS) is a subject of controversy, and no data on their benefit are available from independently controlled multi-center studies. We analyzed data from the prospective randomized SPACE trial, which included 563 patients randomized to CAS and treated per protocol. A total of 145 patients were treated with a PD and 418 without. Of the patients, 436 were treated with an open cell stent and 127 with a closed cell stent. Use of PDs and choice of device was chosen at the individual discretion of the interventionalist. The outcome event (OE) of the analysis (ipsilateral stroke or ipsilateral stroke death within 30 days) was reached in 26/418 patients (6.2%, 95% CI: 4.1 to 9.0%) in the nonprotection [corrected] group and in 12/145 (8.3%, 95% CI: 4.3 to 14.0%) patients in the protection [corrected] group (P=0.40). The OE rate was significantly lower in patients treated with a closed cell stent (5.6% [95% CI: 3.7 to 8.2%]) than in those treated with an open cell stent.(11.0%, 95% CI: 6.2 to 17.8%; P=0.029). Predilatation showed a tendency to but no significant reduction of OE rate. Overall, 49% of all OEs occurred directly periinterventionally, 10% during the navigation procedure and 41% postinterventionally, including 10% of hyperperfusion syndromes. Time point of the event was not influenced by the use of a PD. This secondary analysis of data from the SPACE trial does not support the need for a PD in CAS. Stent design seems to have an impact on the OE rate. Our analysis demonstrates that the choice of the interventional material may have an impact on the periprocedural complication rate in CAS and that the development of more specific stent systems for the treatment of carotid stenosis may reduce the complication rate significantly.

[Brief history of interventional radiology].

PubMed

Tang, Zhenliang; Jia, Aiqin; Li, Luoyun; Li, Chunyu

2014-05-01

In 1923, angiography was first successively used for the human body. In 1953, a Swedish doctor Sven-Ivar Seldinger pioneered the Seldinger technique, which laid down the foundation of interventional radiology. In 1963, Charles Dotter first proposed the idea of interventional radiology. In 1964, Charles Dotter opened a new era of percutaneous angioplasty through accidental operation, marking the formation of interventional radiology. On this basis, the techniques of balloon catheter dilation and metal stent implantation was developed. Endovascular stent was proposed in 1969. In 1973, the percutaneous angioplasty has been a breakthrough with the emergence of soft double-lumen balloon catheter. Percutaneous coronary angioplasty is applied in 1977. Since the 1990s, balloon angioplasty relegated to secondary status with the emergence of metal stent. Currently, endovascular stent have entered a new stage with the emergence of temporary stent and stent grafts and biological stent. Transcatheter arterial embolization had been one of the most important basic techniques for interventional radiology since 1965, it had also been a corresponding development with the improvement of embolic agents and catheter technology for the treatment of diseases now. Transjugular intrahepatic portosystemic stent-shunt is a comprehensive interventional radiology technology since 1967, in which the biliary system can be reached through a jugular vein, and the improvement appeared with balloon expandable stent in 1986.Since 1972, non-vascular interventional techniques was another important branch of interventional radiology. Currently, it is applied in the diagnosis and treatment of many diseases of the internal organs like the pancreas, liver, kidney, spinal cord, Fallopian tubes, esophagus and other organs. In 1973, Chinese radiologist first conducted the angiography test. Interventional radiology was introduced into China in the 1980s, it was readily developed through the sponsoring of training class (1981) and academic conferences (1986). Along with the return of the overseas scholars, the gap in the interventional diagnosis and treatment technology between China and the world has been narrowing since the 1990s.

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.

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.

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.

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

Sommer, C. M., E-mail: christof.sommer@med.uni-heidelberg.de; Grenacher, L.; Stampfl, U.

The purpose of this study was to evaluate the impact of stent design on in-stent stenosis in rabbit iliac arteries. Four different types of stent were implanted in rabbit iliac arteries, being different in stent design (crown or wave) and strut thickness (50 or 100 {mu}m). Ten stents of each type were implanted. Each animal received one crown and one wave stent with the same strut thickness. Follow-up was either 12 weeks (n = 10 rabbits) or 24 weeks (n = 10 rabbits). Primary study end points were angiographic and microscopic in-stent stenosis. Secondary study end points were vessel injury,more » vascular inflammation, and stent endothelialization. Average stent diameter, relative stent overdilation, average and minimal luminal diameter, and relative average and maximum luminal loss were not significantly different. However, a trend to higher relative stent overdilation was recognized in crown stents compared to wave stents. A trend toward higher average and minimal luminal diameter and lower relative average and maximum luminal loss was recognized in crown stents compared to wave stents with a strut thickness of 100 {mu}m. Neointimal height, relative luminal area stenosis, injury score, inflammation score, and endothelialization score were not significantly different. However, a trend toward higher neointimal height was recognized in crown stents compared to wave stents with a strut thickness of 50 {mu}m and a follow-up of 24 weeks. In conclusion, in this study, crown stents seem to trigger neointima. However, the optimized radial force might equalize the theoretically higher tendency for restenosis in crown stents. In this context, also more favorable positive remodeling in crown stents could be important.« less

Silver-nanoparticle-coated biliary stent inhibits bacterial adhesion in bacterial cholangitis in swine.

PubMed

Wen, Wei; Ma, Li-Mei; He, Wei; Tang, Xiao-Wei; Zhang, Yin; Wang, Xiang; Liu, Li; Fan, Zhi-Ning

2016-02-01

One of the major limitations of biliary stents is the stent occlusion, which is closely related to the over-growth of bacteria. This study aimed to evaluate the feasibility of a novel silver-nanoparticle-coated polyurethane (Ag/PU) stent in bacterial cholangitis model in swine. Ag/PU was designed by coating silver nanoparticles on polyurethane (PU) stent. Twenty-four healthy pigs with bacterial cholangitis using Ag/PU and PU stents were randomly divided into an Ag/PU stent group (n=12) and a PU stent group (n=12), respectively. The stents were inserted by standard endoscopic retrograde cholangiopancreatography. Laboratory assay was performed for white blood cell (WBC) count, alanine aminotransferase (ALT), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) at baseline time, 8 hours, 1, 2, 3, and 7 days after stent placements. The segment of bile duct containing the stent was examined histologically ex vivo. Implanted biliary stents were examined by a scan electron microscope. The amount of silver release was also measured in vitro. The number of inflammatory cells and level of ALT, IL-1beta and TNF-alpha were significantly lower in the Ag/PU stent group than in the PU stent group. Hyperplasia of the mucosa was more severe in the PU stent group than in the Ag/PU stent group. In contrast to the biofilm of bacteria on the PU stent, fewer bacteria adhered to the Ag/PU stent. PU biliary stents modified with silver nanoparticles are able to alleviate the inflammation of pigs with bacterial cholangitis. Silver-nanoparticle-coated stents are resistant to bacterial adhesion.

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.

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.

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.

[Percutaneously implantable aortic valve: the JenaValve concept evolution].

PubMed

Figulla, Hans R; Ferrari, Markus

2006-10-01

Due to the increasing incidence of severe aortic stenosis in old and multimorbid patients, the percutaneous implantation of aortic valve-carrying stents has become an alternative to the surgical replacement of aortic valves. Starting in 1995, the authors developed a self-expanding stent which transferred the necessary forces for anchoring up to the aorta ascendens-a conception taken over from CoreValve. The further improvement of this idea over the past 11 years has led to a self-expanding, relatively short stent-valve system that is reliably positioned in the cusps of the old aortic valve and holds the old valve like a paper clip, thus transferring the holding forces physiologically. As compared to conventional systems, the sophisticated insertion catheter requires further chronic animal tests so as to represent a true alternative to the conventional surgical procedure.

Randomized Comparison of Ridaforolimus- and Zotarolimus-Eluting Coronary Stents in Patients With Coronary Artery Disease: Primary Results From the BIONICS Trial (BioNIR Ridaforolimus-Eluting Coronary Stent System in Coronary Stenosis).

PubMed

Kandzari, David E; Smits, Pieter C; Love, Michael P; Ben-Yehuda, Ori; Banai, Shmuel; Robinson, Simon D; Jonas, Michael; Kornowski, Ran; Bagur, Rodrigo; Iniguez, Andres; Danenberg, Haim; Feldman, Robert; Jauhar, Rajiv; Chandna, Harish; Parikh, Manish; Perlman, Gidon Y; Balcells, Mercedes; Markham, Peter; Ozan, Melek Ozgu; Genereux, Philippe; Edelman, Elazer R; Leon, Martin B; Stone, Gregg W

2017-10-03

The safety and efficacy of a novel cobalt alloy-based coronary stent with a durable elastomeric polymer eluting the antiproliferative agent ridaforolimus for treatment of patients with coronary artery disease is undetermined. A prospective, international 1:1 randomized trial was conducted to evaluate in a noninferiority design the relative safety and efficacy of ridaforolimus-eluting stents (RESs) and slow-release zotarolimus-eluting stents among 1919 patients undergoing percutaneous coronary intervention at 76 centers. Inclusion criteria allowed enrollment of patients with recent myocardial infarction, total occlusions, bifurcations lesions, and other complex conditions. Baseline clinical and angiographic characteristics were similar between the groups. Overall, mean age was 63.4 years, 32.5% had diabetes mellitus, and 39.7% presented with acute coronary syndromes. At 12 months, the primary end point of target lesion failure (composite of cardiac death, target vessel-related myocardial infarction, and target lesion revascularization) was 5.4% for both devices (upper bound of 1-sided 95% confidence interval 1.8%, P noninferiority =0.001). Definite/probable stent thrombosis rates were low in both groups (0.4% RES versus 0.6% zotarolimus-eluting stent, P =0.75); 13-month angiographic in-stent late lumen loss was 0.22±0.41 mm and 0.23±0.39 mm ( P noninferiority =0.004) for the RES and zotarolimus-eluting stent groups, respectively, and intravascular ultrasound percent neointimal hyperplasia was 8.10±5.81 and 8.85±7.77, respectively ( P noninferiority =0.01). In the present trial, which allowed broad inclusion criteria, the novel RESs met the prespecified criteria for noninferiority compared with zotarolimus-eluting stents for the primary end point of target lesion failure at 12 months and had similar measures of late lumen loss. These findings support the safety and efficacy of RESs in patients who are representative of clinical practice. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01995487. © 2017 American Heart Association, Inc.

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.

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.

Endotherapy for bile leaks from isolated ducts after hepatic resection: A long awaited challenge.

PubMed

Mutignani, Massimiliano; Forti, Edoardo; Dokas, Stefanos; Pugliese, Francesco; Fontana, Paola; Tringali, Alberto; Dioscoridi, Lorenzo

2017-08-01

Bile leakage is a common complication after hepatic resection [1-4] (Donadon et al., 2016; Dechene et al., 2014; Zimmitti et al., 2013; Yabe et al., 2016). Endotherapy is the treatment of choice for this complication except for bile leaks originating from isolated ducts; a condition resembling the post laparoscopic cholecystectomy Strasberg type C lesions [5-9] (Lillemo et al., 2000; Gupta and Chandra, 2011; Park et al., 2005; Colovic, 2009; Mutignani et al., 2002). In such cases, surgical repair is complex, often of uncertain result and with a high morbidity and mortality [1] (Donadon et al., 2016). On the other hand, percutaneous interventions (i.e. plugging the isolated duct with glue) are technically difficult and risky [7,8] (Park et al., 2005; Colovic, 2009). Endoscopy, thus far, was not considered amongst treatment options. That is because the isolated duct cannot be opacified during cholangiography and is not accessible with the usual endoscopic methods [5,6] (Lillemo et al., 2000; Gupta and Chandra, 2011). Considering the pathophysiology of this type of bile leaks, it is possible to change the pressure gradient endoscopically in order to direct bile flow from the isolated duct towards the duodenal lumen, thus creating an internal biliary fistula to restore bile flow. In order to achieve this goal, we have to perforate the biliary tree into the abdomen. The key element of endoscopic treatment is to create a direct connection between the abdominal cavity and the duodenal lumen by-passing the residual biliary tree with a new technique fully explained in the paper. Our case series (from 2011 to 2016) consists of 13 patients (eight male, five female, mean age 58 years) with fistulas from isolated ducts after various types of hepatic resection. We performed sphincterotomy and placed a biliary stent with the proximal edge inside the intra-abdominal bile collection in 11 patients (eight biliary fully-covered self-expandable metal stents; three plastic stents). In the remaining two patients we successfully cannulated the involved isolated biliary duct and we placed a bridging stent (one fully covered self-expandable metal stent; one plastic stent). Technical and clinical success (considered as fistula healing) was achieved in all 13 patients (mean fistula healing time was four days). Biliary stents were removed three to six months after atrophy of the involved duct in nine cases. In two patients the stent is still in situ. Two patients died with stent in situ due to advanced cancer at 8 and 42 months respectively. Mean follow up was 18 months (range: 8-42 months). The described endoscopic treatment is innovative, safe and effective. It is applicable in tertiary level endoscopic centers and requires considerable expertise. This minimally invasive procedure can increase the rate of fistula healing and will eventually reduce the need for more aggressive and risky surgical procedures. Copyright © 2017 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

OCT assisted identification of the grade of encrustation of urologic catheters

NASA Astrophysics Data System (ADS)

Sroka, Ronald; Püls, Michaela; Stepp, Herbert; Zilinberg, Katja; Bader, Markus; Weidlich, Patrick

2013-06-01

Introduction: Ureteric stenting is a commonly used endourologic procedure for temporary and long-term drainage of an obstructed upper urinary tract. The indication for ureteric stenting is obstruction due to intrinsic (intraureteral stones, strictures, or tumors) or extrinsic (for example compressing pelvic or retroperitoneal mass) causes. Despite the fact that stents do certainly have proven benefits in all fields of urology, there are potential morbidities. The most common problem of indwelling ureteral stents is infection. As foreign body in the urinary system, stents act as a nidus for bacteria colonization, crystallization and encrustation. Bacteria induced biofilm formation predisposes for the crystallization of lithogenic salts, such as calcium-phosphate, calcium-oxalate, magnesium-phosphate on the surface initiating stent encrustation. It was the objective of this study to evaluate whether optical coherence tomography (OCT) using both the surface and the endoluminal technique is feasible to investigate the locations and degree of encrustation process in clinically used ureteral stents. Patients and methods: After removal from patients, fourteen polyurethane JJ stents were investigated. A fresh JJ served as a control. The external surfaces were examined using an endoscopic surface OCT whereas the intraluminal surfaces were investigated by an endoluminal radial OCT device. The focus was on detection of encrustation or crystalline sedimentation. Results: In 12 female and 2 male patients, the median indwelling time of the ureteral catheter was 100 days (range 19- 217). Using the endoluminal OCT, the size and grade of intraluminal encrustation could be expressed as a percentage relating to the open lumen of the reference stent. The maximum encrustation observed resulted in a remaining unrestricted lumen of 15-35% compared to the reference. The luminal reduction caused by encrustation was significantly higher at the proximal end of the ureteral stent as compared to its distal part. The extraluminal OCT-investigations facilitated the characterization of extraluminal encrustation. Conclusion: OCT techniques were feasible and facilitated the detection of encrustation of double pigtail catheters on both the extra and intra luminal surface. Quantitative expression of the degree of intraluminal encrustation could be achieved, with the most dense and thickened occurrence of intraluminal incrustation in the upper curl of the JJ stent.

Effective Endovascular Stenting of Malignant Portal Vein Obstruction in Pancreatic Cancer

PubMed Central

Ellis, Christian M.; Shenoy, Sadashiv; Litwin, Alan; Soehnlein, Stephanie; Gibbs, John F.

2009-01-01

We report herein the case of a patient successfully treated by transhepatic portal venous stent placement for malignant portal vein obstruction with associated gastric and small bowel varices and repeated gastrointestinal bleeding. CT angiography and portography showed severe portal vein obstruction from recurrent pancreatic cancer 15 months following pancreaticoduodenectomy with tumor encasement and dilated collateral veins throughout the gastric and proximal small bowel wall as the suspected cause of the GI bleeding. Successful transhepatic endovascular stent placement of the splenic vein at the portal vein confluence followed by balloon dilation was performed with immediate decompression of the gastric and small bowel varices and relief of GI hemorrhage in this patient until his death four months later. The treatment for patients with this dilemma can prove to be difficult, but as we have shown endovascular stenting of the portal system is an effective treatment option. PMID:19826629

Effective endovascular stenting of malignant portal vein obstruction in pancreatic cancer.

PubMed

Ellis, Christian M; Shenoy, Sadashiv; Litwin, Alan; Soehnlein, Stephanie; Gibbs, John F

2009-01-01

We report herein the case of a patient successfully treated by transhepatic portal venous stent placement for malignant portal vein obstruction with associated gastric and small bowel varices and repeated gastrointestinal bleeding. CT angiography and portography showed severe portal vein obstruction from recurrent pancreatic cancer 15 months following pancreaticoduodenectomy with tumor encasement and dilated collateral veins throughout the gastric and proximal small bowel wall as the suspected cause of the GI bleeding. Successful transhepatic endovascular stent placement of the splenic vein at the portal vein confluence followed by balloon dilation was performed with immediate decompression of the gastric and small bowel varices and relief of GI hemorrhage in this patient until his death four months later. The treatment for patients with this dilemma can prove to be difficult, but as we have shown endovascular stenting of the portal system is an effective treatment option.

[Acute stent thrombosis and reverse transient left ventricular dilatation after performing a single-photon emission computed tomography myocardial perfusion].

PubMed

Miranda, B; Pizzi, M N; Aguadé-Bruix, S; Domingo, E; Candell-Riera, J

2015-01-01

A 63-year-old male patient with a history of stent implantation in the left anterior descending three months before. Due to the presentation of vegetative symptoms, he was referred for gated-SPECT myocardial perfusion. During acquisition of the resting images he presented chest pain and ST segment elevation, so that urgent cardiac catheterization was performed, showing stent thrombosis. Rest perfusion imaging showed a defect in anterior and apical perfusion, more severe and extensive than in the stress images, with striking left ventricular dilatation and a fall in the ejection fraction related to the acute ischemia phenomenon. Intense exercise is associated with a transient activation of the coagulation system and hemodynamic changes that might induce thrombosis, especially in recently implanted coronary stents that probably still have not become completely endothelialized. Copyright © 2014 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

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

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.

Spectral Imaging for Intracranial Stents and Stent Lumen.

PubMed

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

2016-01-01

Application of computed tomography for monitoring intracranial stents is limited because of stent-related artifacts. Our purpose was to evaluate the effect of gemstone spectral imaging on the intracranial stent and stent lumen. In vitro, we scanned Enterprise stent phantom and a stent-cheese complex using the gemstone spectral imaging protocol. Follow-up gemstone spectral images of 15 consecutive patients with placement of Enterprise from January 2013 to September 2014 were also retrospectively reviewed. We used 70-keV, 140-keV, iodine (water), iodine (calcium), and iodine (hydroxyapatite) images to evaluate their effect on the intracranial stent and stent lumen. Two regions of interest were individually placed in stent lumen and adjacent brain tissue. Contrast-to-noise ratio was measured to determine image quality. The maximal diameter of stent markers was also measured to evaluate stent-related artifact. Two radiologists independently graded the visibility of the lumen at the maker location by using a 4-point scale. The mean of grading score, contrast/noise ratio and maximal diameter of stent markers were compared among all modes. All results were analyzed by SPSS version 20. In vitro, iodine (water) images decreased metallic artifact of stent makers to the greatest degree. The most areas of cheese were observed on iodine (water) images. In vivo, iodine (water) images had the smallest average diameter of stent markers (0.33 ± 0.17mm; P < .05) and showed the highest mean grading score (2.94 ± 0.94; P < .05) and contrast/noise ratio of in-stent lumen (160.03 ±37.79; P < .05) among all the modes. Iodine (water) images can help reduce stent-related artifacts of Enterprise and enhance contrast of in-stent lumen. Spectral imaging may be considered a noninvasive modality for following-up patients with in-stent stenosis.

Percutaneous biliary covered stent insertion in patients with malignant duodenobiliary obstruction.

PubMed

Lee, Eunsol; Gwon, Dong Il; Ko, Gi-Young; Sung, Kyu-Bo; Yoon, Hyun-Ki; Shin, Ji Hoon; Kim, Jin Hyoung; Ko, Heung Kyu; Song, Ho-Young

2015-02-01

Although the use of polytetrafluoroethylene (PTFE)-covered biliary stents has proven to be feasible for the treatment of benign and malignant biliary disease, less is known regarding the outcomes of percutaneous placement of a covered stent in patients with malignant duodenobiliary obstruction. To investigate the technical and clinical efficacy of the percutaneous placement of a PTFE-covered biliary stent in patients with malignant duodenobiliary obstruction. From April 2007 to September 2012, the medical records of 45 consecutive patients with malignant duodenobiliary obstruction were retrospectively reviewed. All percutaneous biliary stent deployment was performed using PTFE-covered stents, whereas duodenal stent insertion was performed either fluoroscopically or endoscopically using covered or uncovered stents. Biliary stent deployment was technically successful in all patients. None of the stents migrated after deployment. Procedure-related minor complications, including self-limiting hemobilia, occurred in three (7%) patients. Successful internal drainage was achieved in 39 (87%) of the 45 patients. The median survival time after biliary stent placement was 62 days (95% confidence interval, 8-116 days), and the cumulative stent patency rates at 1, 3, 6, and 12 months were 96%, 92%, 75%, and 38%, respectively. The causes of biliary stent dysfunction included stent occlusion caused by a subsequently inserted duodenal stent (n = 7), food impaction (n = 3), and sludge incrustation (n = 1). One patient developed acute cholecystitis 131 days after biliary stent placement and underwent percutaneous transhepatic gallbladder drainage. Percutaneous insertion of a PTFE-covered stent is a safe and effective method for palliative treatment of patients with malignant duodenobiliary obstruction. If possible, subsequent biliary stent insertion is preferable in order to prevent possible biliary stent dysfunction caused by subsequent insertion of a duodenal stent. © The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Plastic biliary stent patency in patients with locally advanced pancreatic adenocarcinoma receiving downstaging chemotherapy.

PubMed

Ge, Phillip S; Hamerski, Christopher M; Watson, Rabindra R; Komanduri, Srinadh; Cinnor, Birtukan B; Bidari, Kiran; Klapman, Jason B; Lin, Cui L; Shah, Janak N; Wani, Sachin; Donahue, Timothy R; Muthusamy, V Raman

2015-02-01

Plastic stents in patients with biliary obstruction caused by pancreatic adenocarcinoma are typically exchanged at 3-month intervals. Plastic stents may have reduced durability in patients receiving chemotherapy. To determine the duration of plastic biliary stent patency in patients undergoing chemotherapy for pancreatic adenocarcinoma. Retrospective, multicenter cohort study. Three tertiary academic referral centers. A total of 173 patients receiving downstaging chemotherapy for locally advanced or borderline resectable pancreatic adenocarcinoma from 1996 to 2013. Placement of 10F or larger plastic biliary stents. Primary outcome was overall duration of stent patency. Secondary outcomes included the incidence of premature stent exchange (because of cholangitis or jaundice) and hospitalization rates. A total of 233 plastic stents were placed, and the overall median duration of stent patency was 53 days (interquartile range [IQR] 25-99 days). Eighty-seven stents were removed at the time of surgical resection, and 63 stents were exchanged routinely per protocol. The remaining 83 stent exchanges were performed for worsening liver function test results, jaundice, or cholangitis, representing a 35.6% rate of premature stent exchange. The median stent patency duration in the premature stent exchange group was 49 days (IQR 25-91 days) with a 44.6% hospitalization rate. The overall rate of cholangitis was 15.0% of stent exchanges, occurring a median of 56 days after stent placement (IQR 26-89 days). Retrospective study. Plastic biliary stents placed during chemotherapy/chemoradiation for pancreatic adenocarcinoma have a shorter-than-expected patency duration, and a substantial number of patients will require premature stent exchange. Consideration should be given to shortening the interval for plastic biliary stent exchange. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

Application of underdamped Langevin dynamics simulations for the study of diffusion from a drug-eluting stent

NASA Astrophysics Data System (ADS)

Regev, Shaked; Farago, Oded

2018-10-01

We use a one-dimensional two layer model with a semi-permeable membrane to study the diffusion of a therapeutic drug delivered from a drug-eluting stent (DES). The rate of drug transfer from the stent coating to the arterial wall is calculated by using underdamped Langevin dynamics simulations. Our results reveal that the membrane has virtually no delay effect on the rate of delivery from the DES. The work demonstrates the great potential of underdamped Langevin dynamics simulations as an easy to implement, efficient, method for solving complicated diffusion problems in systems with a spatially-dependent diffusion coefficient.

Endovascular Management of Infected Femoral Artery Pseudoaneurysms in High-Risk Patients: A Case Series

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

D’Oria, Mario, E-mail: mario.doria88@outlook.com; Sgorlon, Giada; Calvagna, Cristiano

We report our experience with the urgent treatment of two high-risk patients with infected femoral artery pseudoaneurysms (IFAPs) with the placement of a self-expandable covered stent (SECS). In both cases, there was no perioperative mortality and the aneurysm exclusion was successful without early or late stent thrombosis/stent fracture nor acute or chronic limb ischemia or limb loss. There was no recurrence of local or systemic infection during the follow-up period. Endovascular therapy represents a feasible treatment option for IFAPs in those patients for whom the risk of open surgical repair would be prohibitive, especially under urgent circumstances.

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.

[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.

Genous™ endothelial progenitor cell capturing stent vs. the Taxus Liberté stent in patients with de novo coronary lesions with a high-risk of coronary restenosis: a randomized, single-centre, pilot study

PubMed Central

Beijk, Marcel A.M.; Klomp, Margo; Verouden, Niels J.W.; van Geloven, Nan; Koch, Karel T.; Henriques, José P.S.; Baan, Jan; Vis, Marije M.; Scheunhage, Esther; Piek, Jan J.; Tijssen, Jan G.P.; de Winter, Robbert J.

2010-01-01

Aims The purpose of this study was to evaluate the GenousTM endothelial progenitor cell capturing stent vs. the Taxus Liberté paclitaxel-eluting stent in patients with de novo coronary lesions with a high-risk of coronary restenosis. Methods and results We randomly assigned 193 patients with lesions carrying a high risk of restenosis to have the Genous stent or the Taxus stent implanted. Lesions were considered high risk of restenosis if one of the following applied: chronic total occlusion, lesion length >23 mm, vessel diameter <2.8 mm, or any lesion in a diabetic patient. At 1-year, the rate of the primary end point, target vessel failure (TVF), was 17.3% in the Genous stent group when compared with 10.5% in the Taxus stent group [risk difference (RD) 6.8%, 95% CI −3.1 to 16.7%], a difference predominantly due to a higher incidence of repeat revascularization in patients treated with the Genous stent. In contrast, no stent thrombosis was observed in the Genous stent group compared to 4 stent thromboses in the Taxus stent group (RD −4.2%; 95% CI −10.3 to 0.3%). Repeat angiography between 6 and 12 months in a subgroup of patients showed a significantly higher late loss in the Genous stent compared with the Taxus stent (1.14 ± 0.64 and 0.55 ± 0.61 mm). Conclusion In patients with lesions carrying a high risk of restenosis, the Genous stent resulted in a non-significant higher rate of TVF compared with the Taxus stent mainly due to more repeat revascularizations in the Genous stent group. There were four stent thromboses with Taxus stent, none with the Genous stent. PMID:19933225

Rescue strategy for acute carotid stent thrombosis during carotid stenting with distal filter protection using forced arterial suction thrombectomy with a reperfusion catheter of the Penumbra System: a technical note.

PubMed

Kim, Yong-Won; Kang, Dong-Hun; Hwang, Jeong-Hyun; Park, Jaechan; Hwang, Yang-Ha; Kim, Yong-Sun

2013-08-01

Among the procedural complications related to carotid artery stenting (CAS), internal carotid artery (ICA) flow arrest is one of the most drastic complications, as it can cause major ischemic stroke. Acute carotid stent thrombosis (ACST) is a rare etiology of ICA flow arrest during carotid artery stenting with distal filter protection, but the most devastating. Moreover, no definitive management strategy has been established so far for treating ACST. We introduce a rescue management strategy for differential diagnosis of ICA flow arrest and for recanalization of ACST with a simple endovascular mechanical thrombectomy technique. In three cases of ICA flow arrest caused by ACST, selective angiography with a 1.7 F microcatheter provided confirmative diagnosis. Recanalization was then achieved with a Penumbra System (PS) reperfusion catheter using the forced arterial suction thrombectomy (FAST) technique. Successful recanalization with a Thrombolysis In Cerebral Infarction score of 3 was achieved for all three patients. Recanalization was confirmed with follow-up angiography at least 24 h after the procedure. No complications associated with this technique occurred. Based on our preliminary experiences, selective microangiography can be helpful for rapid diagnosis of ACST, and the present mechanical thrombectomy technique, using a modification of the PS, can play a role in adjuvant management or as a last resort for the treatment of ACST during CAS.

Usefulness of Corsair microcatheter to cross stent struts in bifurcation lesions.

PubMed

Fujimoto, Yoshihide; Iwata, Yo; Yamamoto, Masashi; Kobayashi, Yoshio

2014-01-01

Side branch compromise after stenting in bifurcation lesions is a matter of concern. It may happen that even low-profile balloon catheters do not cross stent struts after rewiring. The Corsair catheter is a hybrid catheter that has features of a microcatheter and a support catheter. The present study evaluated usefulness of the Corsair catheter to facilitate advancing a low-profile balloon catheter through stent struts in bifurcation lesions. After rewiring, low-profile balloon catheters failed to cross stent struts of 29 bifurcation lesions. The Corsair microcatheter successfully crossed stent struts in all lesions except one (97 %) where a stent was implanted to treat in-stent restenosis (stent-in-stent). Low-profile balloon catheters were able to advance into the side branch of all bifurcation lesions where the Corsair microcatheter crossed stent struts. In conclusion, the Corsair microcatheter may be utilized if low-profile balloon catheters are unable to cross stent struts in bifurcation lesions.

Removable esophageal stents have poor efficacy for the treatment of refractory benign esophageal strictures (RBES).

PubMed

Dan, D T; Gannavarapu, B; Lee, J G; Chang, K; Muthusamy, V R

2014-08-01

With the recent availability of removable esophageal stents, endoscopic stenting has been utilized to treat refractory benign esophageal strictures (RBES). The objective of this study was to review the feasibility and effectiveness of removable esophageal stents to treat RBES. Patients who received removable esophageal stents for the treatment of RBES at the institution between 2004-2010 using its stent implantation logs and endoscopic database were retrospectively identified. Patient demographics, stricture etiology and location, stent and procedure characteristics, and clinical outcomes were obtained. Twenty-five patients with a mean age of 70 (72% male) underwent initial stent placement; 24 were successful. Overall clinical success was achieved in five of the 19 patients (26%) ultimately undergoing stent removal. RBES etiologies included anastomotic (13), radiation (5), peptic (3), chemotherapy (1), scleroderma (1), and unknown (2). Alimaxx-E (Merit-Endotek, South Jordan, UT, USA) stents were placed in 20 patients and Polyflex (Boston Scientific, Natick, MA, USA) stents were used in five patients. Immediate complications included failed deployment (1) and chest pain (7). Five patients died prior to stent removal. Stent migration was found in 53% (10/19) of patients who underwent stent removal: nine required additional therapy and one had symptom resolution. Out of the nine patients without stent migration, five required additional therapy and four had symptom resolution. Although placement of removable esophageal stents for RBES is technically feasible, it is frequently complicated by stent migration and chest pain. In addition, few patients achieved long-term stricture resolution after initial stenting. In this study, most patients ultimately required repeated stenting and/or dilations to maintain relief of dysphagia. © 2012 Copyright the Authors. Journal compilation © 2012, Wiley Periodicals, Inc. and the International Society for Diseases of the Esophagus.

Outcomes of Prosthetic Hemodialysis Grafts after Deployment of Bare Metal versus Covered Stents at the Venous Anastomosis

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

Kim, Charles Y., E-mail: charles.kim@duke.edu; Tandberg, Daniel J.; Rosenberg, Michael D.

2012-08-15

Purpose: To compare postintervention patency rates after deployment of bare metal versus covered stents across the venous anastomosis of prosthetic arteriovenous (AV) grafts. Methods: Review of our procedural database over a 6 year period revealed 377 procedures involving stent deployment in an AV access circuit. After applying strict inclusion criteria, our study group consisted of 61 stent deployments in 58 patients (median age 58 years, 25 men, 33 women) across the venous anastomosis of an upper extremity AV graft circuit that had never been previously stented. Both patent and thrombosed AV access circuits were retrospectively analyzed. Within the bare metalmore » stent group, 20 of 32 AV grafts were thrombosed at initial presentation compared to 18 of 29 AV grafts in the covered stent group. Results: Thirty-two bare metal stents and 29 covered stents were deployed across the venous anastomosis. The 3, 6, and 12 months primary access patency rates for bare metal stents were not significantly different than for covered stents: 50, 41, and 22 % compared to 59, 52, and 29 %, respectively (p = 0.21). The secondary patency rates were also not significantly different: 78, 78, and 68 % for bare metal stents compared to 76, 69, and 61 % for covered stents, respectively (p = 0.85). However, covered stents demonstrated a higher primary stent patency rate than bare metal stents: 100, 85, and 70 % compared to 75, 67, and 49 % at 3, 6, and 12 months (p < 0.01). Conclusion: The primary and secondary access patency rates after deployment of bare metal versus covered stents at the venous anastomosis were not significantly different. However, bare metal stents developed in-stent stenoses significantly sooner.« less

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.

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.

Evaluation of anti-migration properties of biliary covered self-expandable metal stents.

PubMed

Minaga, Kosuke; Kitano, Masayuki; Imai, Hajime; Harwani, Yogesh; Yamao, Kentaro; Kamata, Ken; Miyata, Takeshi; Omoto, Shunsuke; Kadosaka, Kumpei; Sakurai, Toshiharu; Nishida, Naoshi; Kudo, Masatoshi

2016-08-14

To assess anti-migration potential of six biliary covered self-expandable metal stents (C-SEMSs) by using a newly designed phantom model. In the phantom model, the stent was placed in differently sized holes in a silicone wall and retracted with a retraction robot. Resistance force to migration (RFM) was measured by a force gauge on the stent end. Radial force (RF) was measured with a RF measurement machine. Measured flare structure variables were the outer diameter, height, and taper angle of the flare (ODF, HF, and TAF, respectively). Correlations between RFM and RF or flare variables were analyzed using a linear correlated model. Out of the six stents, five stents were braided, the other was laser-cut. The RF and RFM of each stent were expressed as the average of five replicate measurements. For all six stents, RFM and RF decreased as the hole diameter increased. For all six stents, RFM and RF correlated strongly when the stent had not fully expanded. This correlation was not observed in the five braided stents excluding the laser cut stent. For all six stents, there was a strong correlation between RFM and TAF when the stent fully expanded. For the five braided stents, RFM after full stent expansion correlated strongly with all three stent flare structure variables (ODF, HF, and TAF). The laser-cut C-SEMS had higher RFMs than the braided C-SEMSs regardless of expansion state. RF was an important anti-migration property when the C-SEMS did not fully expand. Once fully expanded, stent flare structure variables plays an important role in anti-migration.

Double-layered PTFE-covered nitinol stents: experience in 32 patients with malignant esophageal strictures.

PubMed

Park, Jung Gu; Jung, Gyoo-Sik; Oh, Kyung Seung; Park, Seon-Ja

2010-08-01

We evaluated the effectiveness of a double-layered polytetrafluoroethylene (PTFE)-covered nitinol stent in the palliative treatment of malignant esophageal strictures. A double-layered PTFE-covered nitinol stent was designed to reduce the propensity to migration of conventional covered stent. The stent consists of an inner PTFE-covered stent and an outer uncovered nitinol stent tube. With fluoroscopic guidance, the stent was placed in 32 consecutive patients with malignant esophageal strictures. During the follow-up period, the technical and clinical success rates, complications, and cumulative patient survival and stent patency were evaluated. Stent placement was technically successful in all patients, and no procedural complications occurred. After stent placement, the symptoms of 30 patients (94%) showed improvement. During the mean follow-up of 103 days (range, 9-348 days), 11 (34%) of 32 patients developed recurrent symptoms due to tumor overgrowth in five patients (16%), tumor ingrowth owing to detachment of the covering material (PTFE) apart from the stent wire in 3 (9%), mucosal hyperplasia in 2 (6%), and stent migration in 1 (3%). Ten of these 11 patients were treated by means of placing a second covered stent. Thirty patients died, 29 as a result of disease progression and 1 from aspiration pneumonia. The median survival period was 92 days. The median period of primary stent patency was 190 days. The double-layered PTFE-covered nitinol stent seems to be effective for the palliative treatment of malignant esophageal strictures. We believe that the double-layer configuration of this stent can contribute to decreasing the stent's migration rate.

Incidence of urinary extravasation and rate of ureteral stenting after high-grade renal trauma in adults: a meta-analysis

PubMed Central

Anderson, Ross E.; Fiander, Michelle; McFarland, Mary M.; Stoddard, Gregory J.; Hotaling, James M.; Myers, Jeremy B.

2018-01-01

Background Collecting system injury and urinary extravasation is an important yet understudied aspect of renal trauma. We aimed to examine the incidence of urinary extravasation and also the rates of ureteral stenting after high-grade renal trauma (HGRT) in adults. Methods A search strategy was developed to search Ovid Medline, Embase, CINAHL, and Cochrane Library. Two reviewers screened titles and abstracts, followed by full-text review of the relevant publications. Studies were included if they indicated the number of patients with HGRT [the American Association for the Surgery of Trauma (AAST) grades III–IV or equivalents] and number of patients with urinary extravasation. A descriptive meta-analysis of binary proportions was performed with random-effects model to calculate the incidence of urinary extravasation and rates of ureteral stenting. Results After screening, 24 and 20 studies were included for calculating urinary extravasation and stenting rates, respectively. Most studies involved blunt injury and were retrospective single-center case series. Incidence of urinary extravasation was 29% (95% CI: 17–42%) after HGRT (grade III–V), and 51% (95% CI: 38–64%) when only grade IV–V injuries were combined. Overall, 29% (95% CI: 22–36%) of patients with urinary extravasation underwent ureteral stenting. Conclusions Approximately 30% of patients with HGRT are diagnosed with urinary extravasation and 29% of those with urinary extravasation undergo ureteral stenting. Understanding the rate of urinary extravasation and interventions is the first step in creating a prospective trial designed to demonstrate when ureteral stenting and aggressive management of urinary extravasation is needed. PMID:29928614

Incidence of urinary extravasation and rate of ureteral stenting after high-grade renal trauma in adults: a meta-analysis.

PubMed

Keihani, Sorena; Anderson, Ross E; Fiander, Michelle; McFarland, Mary M; Stoddard, Gregory J; Hotaling, James M; Myers, Jeremy B

2018-05-01

Collecting system injury and urinary extravasation is an important yet understudied aspect of renal trauma. We aimed to examine the incidence of urinary extravasation and also the rates of ureteral stenting after high-grade renal trauma (HGRT) in adults. A search strategy was developed to search Ovid Medline, Embase, CINAHL, and Cochrane Library. Two reviewers screened titles and abstracts, followed by full-text review of the relevant publications. Studies were included if they indicated the number of patients with HGRT [the American Association for the Surgery of Trauma (AAST) grades III-IV or equivalents] and number of patients with urinary extravasation. A descriptive meta-analysis of binary proportions was performed with random-effects model to calculate the incidence of urinary extravasation and rates of ureteral stenting. After screening, 24 and 20 studies were included for calculating urinary extravasation and stenting rates, respectively. Most studies involved blunt injury and were retrospective single-center case series. Incidence of urinary extravasation was 29% (95% CI: 17-42%) after HGRT (grade III-V), and 51% (95% CI: 38-64%) when only grade IV-V injuries were combined. Overall, 29% (95% CI: 22-36%) of patients with urinary extravasation underwent ureteral stenting. Approximately 30% of patients with HGRT are diagnosed with urinary extravasation and 29% of those with urinary extravasation undergo ureteral stenting. Understanding the rate of urinary extravasation and interventions is the first step in creating a prospective trial designed to demonstrate when ureteral stenting and aggressive management of urinary extravasation is needed.

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

The biodurability of covering materials for metallic stents in a bile flow phantom.

PubMed

Bang, Byoung Wook; Jeong, Seok; Lee, Don Haeng; Lee, Jung Il; Lee, Se Chul; Kang, Sung-Gwon

2012-04-01

Covered biliary metal stents have been introduced for the purpose of overcoming tumor ingrowth and treatment of benign biliary stricture. The aim of this study was to evaluate the biodurability of three commercially available biliary metal stent covering materials [e-PTFE (expanded polytetrafluoroethylene), silicone, and polyurethane] in a bile flow phantom. By operation of a peristaltic pump, human bile was circulated continuously in an experimental perfusion system containing covered metal stents. Each stent was removed, respectively, 1, 2, 4, and 6 months after bile exposure. We performed a gross inspection of the covered stents. The covering membrane was detached from the stent and observed by scanning electron microscopy (SEM). Finally, we measured tensile and tear strength of the membranes. Bile-staining of the membrane showed gradual progression after bile exposure; however, progress was the fastest in e-PTFE. SEM examination showed that the polyurethane surface was smooth, and the silicone surface was relatively smooth. However, e-PTFE had a rough and uneven surface. After bile exposure, there were no significant changes in polyurethane and silicone; however, biofilms and microcracks were observed in e-PTFE. In contrast to a gradual decrease of tensile/tear strength of polyurethane and silicone, those of e-PTFE showed a rapid reduction despite of the strongest baseline tensile and tear strength. e-PTFE tended to form biofilms more frequently than polyurethane and silicone during bile exposure. e-PTFE seemed to be less durable than silicone and polyurethane, however, as clinically applicable material because of strong absolute tensile/tear strengths.

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

Park, Jung Gu; Jung, Gyoo-Sik, E-mail: gsjung@medimail.co.kr; Oh, Kyung Seung

We evaluated the effectiveness of a double-layered polytetrafluoroethylene (PTFE)-covered nitinol stent in the palliative treatment of malignant esophageal strictures. A double-layered PTFE-covered nitinol stent was designed to reduce the propensity to migration of conventional covered stent. The stent consists of an inner PTFE-covered stent and an outer uncovered nitinol stent tube. With fluoroscopic guidance, the stent was placed in 32 consecutive patients with malignant esophageal strictures. During the follow-up period, the technical and clinical success rates, complications, and cumulative patient survival and stent patency were evaluated. Stent placement was technically successful in all patients, and no procedural complications occurred. Aftermore » stent placement, the symptoms of 30 patients (94%) showed improvement. During the mean follow-up of 103 days (range, 9-348 days), 11 (34%) of 32 patients developed recurrent symptoms due to tumor overgrowth in five patients (16%), tumor ingrowth owing to detachment of the covering material (PTFE) apart from the stent wire in 3 (9%), mucosal hyperplasia in 2 (6%), and stent migration in 1 (3%). Ten of these 11 patients were treated by means of placing a second covered stent. Thirty patients died, 29 as a result of disease progression and 1 from aspiration pneumonia. The median survival period was 92 days. The median period of primary stent patency was 190 days. The double-layered PTFE-covered nitinol stent seems to be effective for the palliative treatment of malignant esophageal strictures. We believe that the double-layer configuration of this stent can contribute to decreasing the stent's migration rate.« less

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.

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/or secondary procedure) might provide longer cumulative stent patency and survival than using uncovered SEMSs in both procedures.

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

ST-Segment Elevation Myocardial Infarction with Acute Stent Thrombosis Presenting as Intractable Hiccups: An Unusual Case

PubMed Central

Zhang, Fan; Tongo, Nosakhare Douglas; Hastings, Victoria; Kanzali, Parisa; Zhu, Ziqiang; Chadow, Hal; Rafii, Shahrokh E.

2017-01-01

Patient: Male, 51 Final Diagnosis: ST-segment elevation myocardial infarction with acute stent thrombosis Symptoms: Chest pain • hiccups Medication: — Clinical Procedure: — Specialty: Cardiology Objective: Unusual clinical course Background: Acute coronary syndrome (ACS) can present with atypical chest pain or symptoms not attributed to heart disease, such as indigestion. Hiccups, a benign and self-limited condition, can become persistent or intractable with overlooked underlying etiology. There are various causes of protracted hiccups, including metabolic abnormalities, psychogenic disorders, malignancy, central nervous system pathology, medications, pulmonary disorders, or gastrointestinal etiologies. It is rarely attributed to cardiac disease. Case Report: We report a case of intractable hiccups in a 51-year-old male with cocaine related myocardial infarction (MI) before and after stent placement. Coronary angiogram showed in-stent thrombosis of the initial intervention. Following thrombectomy, balloon angioplasty, and stent, the patient recovered well without additional episodes of hiccups. Although hiccups are not known to present with a predilection for a particular cause of myocardial ischemia, this case may additionally be explained by the sympathomimetic effects of cocaine, which lead to vasoconstriction of coronary arteries. Conclusions: Hiccups associated with cardiac enzyme elevation and EKG ST-segment elevation before and after percutaneous coronary intervention (PCI) maybe a manifestation of acute MI with or without stent. The fact that this patient was a cocaine user may have contributed to the unique presentation. PMID:28455489

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.

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

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.

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.

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.

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.

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-metal stents at 2-year follow-up. In randomised studies completed to date, CoCr-EES has the lowest rate of stent thrombosis within 2 years of implantation. The finding that CoCr-EES also reduced stent thrombosis compared with bare-metal stents, if confirmed in future randomised trials, represents a paradigm shift. The Cardiovascular Research Foundation. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

Renal artery stent fracture with refractory hypertension: a case report and review of the literature.

PubMed

Chua, Su-Kiat; Hung, Huei-Fong

2009-07-01

A 73-year-old man with resistant hypertension and impaired renal function underwent stenting for right renal artery (RRA) stenosis. Two years later, he presented with uncontrolled hypertension and worse renal function. Renal arteriogram revealed RRA stent fracture with in-stent restenosis. Another stent was deployed. Four months later, however, renal arteriogram revealed in-stent restenosis again. This time, balloon angioplasty alone was performed. He had been symptom-free with stable condition at 2-year follow-up. A literature review disclosed six renal artery stent fracture cases, including the present one, who developed in-stent stenosis resulted from stent fracture. Two major anatomy features of renal artery stenosis were suggestive for development of stent fracture: (1) renal artery entrapment by diaphragmatic crus, and (2) mobile kidney with acute angulation at proximal segment of the renal artery. It is important to detect this etiology of renal artery stenosis because stenting in these vessels may contribute to in-stent restenosis or stent fracture. Management of renal artery stent fracture, including endovascular treatment or aortorenal bypass, should be considered on a case-by-case basis in relation to clinical settings. Copyright 2009 Wiley-Liss, Inc.

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.

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

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.

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

Evaluation of anti-migration properties of biliary covered self-expandable metal stents

PubMed Central

Minaga, Kosuke; Kitano, Masayuki; Imai, Hajime; Harwani, Yogesh; Yamao, Kentaro; Kamata, Ken; Miyata, Takeshi; Omoto, Shunsuke; Kadosaka, Kumpei; Sakurai, Toshiharu; Nishida, Naoshi; Kudo, Masatoshi

2016-01-01

AIM: To assess anti-migration potential of six biliary covered self-expandable metal stents (C-SEMSs) by using a newly designed phantom model. METHODS: In the phantom model, the stent was placed in differently sized holes in a silicone wall and retracted with a retraction robot. Resistance force to migration (RFM) was measured by a force gauge on the stent end. Radial force (RF) was measured with a RF measurement machine. Measured flare structure variables were the outer diameter, height, and taper angle of the flare (ODF, HF, and TAF, respectively). Correlations between RFM and RF or flare variables were analyzed using a linear correlated model. RESULTS: Out of the six stents, five stents were braided, the other was laser-cut. The RF and RFM of each stent were expressed as the average of five replicate measurements. For all six stents, RFM and RF decreased as the hole diameter increased. For all six stents, RFM and RF correlated strongly when the stent had not fully expanded. This correlation was not observed in the five braided stents excluding the laser cut stent. For all six stents, there was a strong correlation between RFM and TAF when the stent fully expanded. For the five braided stents, RFM after full stent expansion correlated strongly with all three stent flare structure variables (ODF, HF, and TAF). The laser-cut C-SEMS had higher RFMs than the braided C-SEMSs regardless of expansion state. CONCLUSION: RF was an important anti-migration property when the C-SEMS did not fully expand. Once fully expanded, stent flare structure variables plays an important role in anti-migration. PMID:27570427

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).

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.

Technical feasibility and revision efficacy of the sequential deployment of endoscopic bilateral side-by-side metal stents for malignant hilar biliary strictures: a multicenter prospective study.

PubMed

Lee, Tae Hoon; Park, Do Hyun; Lee, Sang Soo; Choi, Hyun Jong; Lee, Jun Kyu; Kim, Tae Hyeon; Kim, Jong Hyeok; Jeong, Seok; Park, Sang-Heum; Moon, Jong Ho

2013-02-01

Theoretically, the side-by-side bilateral placement of metal stents may be technically easier than stent-in-stent bilateral placement in stent revision. However, side-by-side placement can be technically challenging, as the deployment of the first stent can preclude the passage of the second stent. We explored the technical feasibility and revision efficacy of endoscopic bilateral side-by-side stent placement for malignant hilar biliary strictures. Forty-four patients with Bismuth type II or higher malignant hilar biliary strictures were enrolled in seven academic tertiary referral centers. Endoscopic placement of side-by-side bilateral metal stents with 7F thin delivery shaft was performed. The outcome measurements were the technical and functional success, adverse events, endoscopic revision success rate, and stent patency. Overall, the technical and functional success rates were 91 % (40/44), and 98 % (39/40), respectively. Two of the failed patients were converted successfully with subsequent contralateral stent-in-stent placement, and the other patients underwent percutaneous intervention. Early stent-related adverse events occurred in 10 %. The endoscopic revision rate due to stent malfunction during follow-up (median: 180 days) was 45 % (18/40; tumor ingrowth in 4 and in-stent sludge impaction/stone formation in 14 patients). The endoscopic revision success rate was 92 % (12/13). Five patients with comorbidity underwent initial percutaneous intervention. The median survival and stent patency periods were 180 and 157 days, respectively. The sequential placement of a metal stent with a 7F thin delivery shaft in bilateral side-by-side procedures may be feasible and effective for malignant hilar biliary strictures and for endoscopic stent revision.

Effect of longitudinal anatomical mismatch of stenting on the mechanical environment in human carotid artery with atherosclerotic plaques.

PubMed

Fan, Zhenmin; Liu, Xiao; Sun, Anqiang; Zhang, Nan; Fan, Zhanming; Fan, Yubo; Deng, Xiaoyan

2017-10-01

Longitudinal anatomic mismatch (LAM) of stenting (i.e., a stenotic artery segment is not fully covered by a deployed stent) worsens the mechanical environment in the treated artery, which most likely is the cause for the associated high risks of restenosis, myocardial infarction and stent thrombosis. To probe the possibility, we constructed a patient-specific carotid model with two components of plaques (lipid and calcified plaque) based on MRI images; we numerically compared three different stenting scenarios in terms of von Mises stress (VMS) distribution in the treated arteries, namely, the short stenting (LAM), the medium stenting and the long stenting. The results showed that the short stenting led to more areas with abnormally high VMS along the inner surface of the treated artery with a much higher surface-averaged VMS at the distal end of the stent than both the medium and long stenting. While the VMS distribution in the calcified plaques was similar for the three stenting models, it was quite different in the lipid plaques among the three stenting models. The lipid plaque of the short-stent model showed more volume of the lipid plaque subjected to high VMS than those of the other two models. Based on the obtained results, we may infer that the short stenting (i.e., LAM) may aggravate vascular injury due to high VMS on the artery-stent interaction surface and within the lipid plaque. Therefore, to obtain a better outcome, a longer stent, rather than a short one, might be needed for arterial stenting. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Immediate, short‐, and long‐term changes in tracheal stent diameter, length, and positioning after placement in dogs with tracheal collapse syndrome

PubMed Central

Raske, Matthew; Berent, Allyson C.; McDougall, Renee; Lamb, Kenneth

2018-01-01

Background Intraluminal tracheal stenting is a minimally invasive procedure shown to have variable degrees of success in managing clinical signs associated with tracheal collapse syndrome (CTCS) in dogs. Objectives Identify immediate post‐stent changes in tracheal diameter, determine the extent of stent migration, and stent shortening after stent placement in the immediate‐, short‐, and long‐term periods, and evaluate inter‐observer reliability of radiographic measurements. Animals Fifty client‐owned dogs. Methods Retrospective study in which medical records were reviewed in dogs with CTCS treated with an intraluminal tracheal stent. Data collected included signalment, location, and type of collapse, stent diameter and length, and post‐stent placement radiographic follow‐up times. Radiographs were used to obtain pre‐stent tracheal measurements and post‐stent placement measurements. Results Immediate mean percentage change was 5.14%, 5.49%, and 21.64% for cervical, thoracic inlet, and intra‐thoracic tracheal diameters, respectively. Ultimate mean follow‐up time was 446 days, with mean percentage change of 2.55%, 15.09%, and 8.65% for cervical, thoracic inlet, and intra‐thoracic tracheal diameters, respectively. Initial mean stent length was 26.72% higher than nominal length and ultimate long‐term tracheal mean stent shortening was only 9.90%. No significant stent migration was identified in the immediate, short‐, or long‐term periods. Good inter‐observer agreement of radiographic measurements was found among observers of variable experience level. Conclusions and Clinical Importance Use of an intraluminal tracheal stent for CTCS is associated with minimal stent shortening with no clinically relevant stent migration after fluoroscopic placement. Precise stent sizing and placement techniques likely play important roles in avoiding these reported complications. PMID:29460368

Immediate, short-, and long-term changes in tracheal stent diameter, length, and positioning after placement in dogs with tracheal collapse syndrome.

PubMed

Raske, Matthew; Weisse, Chick; Berent, Allyson C; McDougall, Renee; Lamb, Kenneth

2018-03-01

Intraluminal tracheal stenting is a minimally invasive procedure shown to have variable degrees of success in managing clinical signs associated with tracheal collapse syndrome (CTCS) in dogs. Identify immediate post-stent changes in tracheal diameter, determine the extent of stent migration, and stent shortening after stent placement in the immediate-, short-, and long-term periods, and evaluate inter-observer reliability of radiographic measurements. Fifty client-owned dogs. Retrospective study in which medical records were reviewed in dogs with CTCS treated with an intraluminal tracheal stent. Data collected included signalment, location, and type of collapse, stent diameter and length, and post-stent placement radiographic follow-up times. Radiographs were used to obtain pre-stent tracheal measurements and post-stent placement measurements. Immediate mean percentage change was 5.14%, 5.49%, and 21.64% for cervical, thoracic inlet, and intra-thoracic tracheal diameters, respectively. Ultimate mean follow-up time was 446 days, with mean percentage change of 2.55%, 15.09%, and 8.65% for cervical, thoracic inlet, and intra-thoracic tracheal diameters, respectively. Initial mean stent length was 26.72% higher than nominal length and ultimate long-term tracheal mean stent shortening was only 9.90%. No significant stent migration was identified in the immediate, short-, or long-term periods. Good inter-observer agreement of radiographic measurements was found among observers of variable experience level. Use of an intraluminal tracheal stent for CTCS is associated with minimal stent shortening with no clinically relevant stent migration after fluoroscopic placement. Precise stent sizing and placement techniques likely play important roles in avoiding these reported complications. Copyright © 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

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

Titanium-nitride-oxide-coated coronary stents: insights from the available evidence.

PubMed

Karjalainen, Pasi P; Nammas, Wail

2017-06-01

Coating of stent surface with a biocompatible material is suggested to improve stent safety profile. A proprietary process was developed to coat titanium-nitride-oxide on the stent surface, based on plasma technology that uses the nano-synthesis of gas and metal. Preclinical in vitro and in vivo investigation confirmed blood compatibility of titanium (nitride-) oxide films. Titanium-nitride-oxide-coated stents demonstrated a better angiographic outcome, compared with bare-metal stents at mid-term follow-up; however, they failed to achieve non-inferiority for angiographic outcome versus second-generation drug-eluting stents. Observational studies showed adequate clinical outcome at mid-term follow-up. Non-randomized studies showed an outcome of titanium-nitride-oxide-coated stents comparable to - or better than - first-generation drug-eluting stents at long-term follow-up. Two randomized controlled trials demonstrated comparable efficacy outcome, and a better safety outcome of titanium-nitride-oxide-coated stents versus drug-eluting stents at long-term follow-up. Evaluation by optical coherence tomography at mid-term follow-up revealed better neointimal strut coverage associated with titanium-nitride-oxide-coated stents versus drug-eluting stents; yet, neointimal hyperplasia thickness was greater. Key messages Stents coated with titanium-nitride-oxide demonstrated biocompatibility in preclinical studies: they inhibit platelet and fibrin deposition, and reduce neointimal growth. In observational and non-randomized studies, titanium-nitride-oxide-coated stents were associated with adequate safety and efficacy outcome. In randomized trials of patients with acute coronary syndrome, titanium-nitride-oxide-coated stents were associated with a better safety outcome, compared with drug-eluting stents; efficacy outcome was comparable.

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.

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.

The "Hitch Stitch": An Effective Method of Preventing Migration in High Tracheal Stenosis.

PubMed

Mehta, Ravindra M; Singla, Abhinav; Shah, Aashish; Loknath, Chakravarthi

2017-01-01

The incidence of caudal stent migration in high tracheal stenting is 13-21% and is common with silicone stents. This can lead to major problems, including emergency repeat procedures. Several antimigration methods are described, but have limitations in terms of their success rate, availability, cost or ease of the procedure. We describe an innovative method of stent migration prevention using a simple percutaneous anchoring "hitch stitch", validated in a large series. After tracheal stent placement, an Ethilon suture was passed into the stent lumen through an 18-G needle. To take this suture back to the exterior to complete the stitch, a retrieval loop was passed through another 14-G percutaneous cannula inserted into the stent lumen. Bronchoscopically, using a forceps the first suture was pulled inside the loop, the loop was retracted, the suture was exteriorized, and the knot was completed and embedded subcutaneously. While removing the stent, an endoscopic scissor was used to cut the stitch to free the stent. A total of 42 "hitch stitches" were done in 29 patients over 5 years, predominantly for silicone stents. Indications for stenting included postintubation tracheal stenosis (83.3%), malignancy (11.9%) and tracheoesophageal fistula (4.8%, metal stents). The procedure was successful in 41/42 (97.6%) patients. Stitch removal was uncomplicated. This is the largest series of an external stent anchoring procedure as a migration prevention strategy in high tracheal stenting, applicable to both silicone and metal stents. Stent migration prevention using this "hitch stitch" is simple, safe and successful, without any complications during stent removal. © 2016 S. Karger AG, Basel.

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.

Process development for high-resolution 3D-printing of bioresorbable vascular stents

NASA Astrophysics Data System (ADS)

Ware, Henry Oliver T.; Farsheed, Adam C.; van Lith, Robert; Baker, Evan; Ameer, Guillermo; Sun, Cheng

2017-02-01

The recent development of "continuous projection microstereolithography" also known as CLIP technology has successfully alleviated the main obstacles surrounding 3D printing technologies: production speed and part quality. Following the same working principle, we further developed the μCLIP process to address the needs for high-resolution 3D printing of biomedical devices with micron-scale precision. Compared to standard stereolithography (SLA) process, μCLIP fabrication can reduce fabrication time from several hours to as little as a few minutes. μCLIP can also produce better surface finish and more uniform mechanical properties than conventional SLA, as each individual "fabrication layer" continuously polymerizes into the subsequent layer. In this study, we report the process development in manufacturing high-resolution bioresorbable stents using our own μCLIP system. The bioresorbable photopolymerizable biomaterial (B-ink) used in this study is methacrylated poly(1, 12 dodecamethylene citrate) (mPDC). Through optimization of our μCLIP process and concentration of B-ink components, we have created a customizable bioresorbable stent with similar mechanical properties exhibited by nitinol stents. Upon optimization, fabricating a 2 cm tall vascular stent that comprises 4000 layers was accomplished in 26.5 minutes.

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.

ST-Segment Elevation Myocardial Infarction with Acute Stent Thrombosis Presenting as Intractable Hiccups: An Unusual Case.

PubMed

Zhang, Fan; Tongo, Nosakhare Douglas; Hastings, Victoria; Kanzali, Parisa; Zhu, Ziqiang; Chadow, Hal; Rafii, Shahrokh E

2017-04-29

BACKGROUND Acute coronary syndrome (ACS) can present with atypical chest pain or symptoms not attributed to heart disease, such as indigestion. Hiccups, a benign and self-limited condition, can become persistent or intractable with overlooked underlying etiology. There are various causes of protracted hiccups, including metabolic abnormalities, psychogenic disorders, malignancy, central nervous system pathology, medications, pulmonary disorders, or gastrointestinal etiologies. It is rarely attributed to cardiac disease. CASE REPORT We report a case of intractable hiccups in a 51-year-old male with cocaine related myocardial infarction (MI) before and after stent placement. Coronary angiogram showed in-stent thrombosis of the initial intervention. Following thrombectomy, balloon angioplasty, and stent, the patient recovered well without additional episodes of hiccups. Although hiccups are not known to present with a predilection for a particular cause of myocardial ischemia, this case may additionally be explained by the sympathomimetic effects of cocaine, which lead to vasoconstriction of coronary arteries. CONCLUSIONS Hiccups associated with cardiac enzyme elevation and EKG ST-segment elevation before and after percutaneous coronary intervention (PCI) maybe a manifestation of acute MI with or without stent. The fact that this patient was a cocaine user may have contributed to the unique presentation.

A new idea for a safer approach to the supra-aortic trunks: the Piton™ catheter.

PubMed

Setacci, C; Moratto, R; Sirignano, P; Setacci, F; Silingardi, R; Coppi, G

2011-04-01

Carotid artery disease is among the most common causes of stroke, and stroke is the third leading cause of death in industrialized countries. Thus the personal health and socioeconomic burden of carotid artery disease is significant. Carotid artery disease accounts for approximately 5-12% of new strokes in patients amenable to revascularization therapy. Atherosclerosis is the main reason for stroke and accounts for approximately one third of all cases. Carotid stenting is nowadays considered a valid standard alternative to surgical carotid endarterectomy, especially in patients having a high perioperative risk. The first carotid balloon angioplasty was carried out in 1979 and the first carotid balloon-expandable bare metal stents were implanted 10 years later, in 1989. However, carotid stenting at that time was associated with major complications, due to extrinsic compression and subsequent to the steel stents used. The Piton™ GC (carotid guide catheter) is intended to facilitate the introduction and placement of interventional devices (e.g., guidewires, stent delivery systems, dilation balloons, angiographic- or micro-catheters, etc.) into the human vasculature to treat vascular obstructive disease, including but not limited to the supra-aortic vessels.

Clinical outcome of endoscopic covered metal stenting for resolution of benign biliary stricture: Systematic review and meta-analysis.

PubMed

Zheng, Xiao; Wu, Jun; Sun, Bo; Wu, Ye-Chen; Bo, Zhi-Yuan; Wan, Wei; Gao, Dao-Jian; Hu, Bing

2017-03-01

Management of benign biliary stricture is challenging. Endoscopic therapy has evolved as the first-line treatment for various benign biliary strictures. However, covered self-expandable metal stents (CSEMS) have not been approved by the United States Food and Drug Administration for the treatment of benign biliary stricture. With this goal, we conducted the present systemic review and meta-analysis to evaluate the efficacy and safety of endoscopic stenting with CSEMS in the treatment of benign biliary stricture. Systematic review and meta-analysis by searching PubMed, MEDLINE and Embase databases. In total, 37 studies (1677 patients) fulfilled the inclusion criteria. Pooled stricture resolutions were achieved in 83% of cases. Median stent dwelling time was 4.4 months, with median endoscopic retrograde cholangiopancreatography sessions of 2.0. Stricture recurrence at 4-year follow up was 11% (95% CI, 8-14%). Pooled complication rate was 23% (95% CI, 20-26%). Placement of CSEMS is effective in the treatment of benign biliary stricture with relatively short stenting duration and low long-term stricture recurrence rate. However, more prospectively randomized studies are required to confirm the results. © 2016 Japan Gastroenterological Endoscopy Society.

Cost-effectiveness of drug-eluting stents in patients at high or low risk of major cardiac events in the Basel Stent KostenEffektivitäts Trial (BASKET): an 18-month analysis.

PubMed

Brunner-La Rocca, Hans Peter; Kaiser, Christoph; Bernheim, Alain; Zellweger, Michael J; Jeger, Raban; Buser, Peter T; Osswald, Stefan; Pfisterer, Matthias

2007-11-03

Our aim was to determine whether drug-eluting stents are good value for money in long-term, everyday practice. We did an 18-month cost-effectiveness analysis of the Basel Stent KostenEffektivitäts Trial (BASKET), which randomised 826 patients 2:1 to drug-eluting stents (n=545) or to bare-metal stents (281). We used non-parametric bootstrap techniques to determine incremental cost-effectiveness ratios (ICERs) of drug-eluting versus bare-metal stents, to compare low-risk (> or =3.0 mm stents in native vessels; n=558, 68%) and high-risk patients (<3.0 mm stents/bypass graft stenting; n=268, 32%), and to do sensitivity analyses by altering costs and event rates in the whole study sample and in predefined subgroups. Quality-adjusted life-years (QALYs) were assessed by EQ-5D questionnaire (available in 703/826 patients). Overall costs were higher for patients with drug-eluting stents than in those with bare-metal stents (11,808 euros [SD 400] per patient with drug-eluting stents and 10,450 euros [592] per patient with bare-metal stents, mean difference 1358 euros [717], p<0.0001), due to higher stent costs. We calculated an ICER of 64,732 euros to prevent one major adverse cardiac event, and of 40,467 euros per QALY gained. Stent costs, number of events, and QALYs affected ICERs most, but unrealistic alterations would have been required to achieve acceptable cost-effectiveness. In low-risk patients, the probability of drug-eluting stents achieving an arbitrary ICER of 10,000 euros or less to prevent one major adverse cardiac event was 0.016; by contrast, it was 0.874 in high-risk patients. If used in all patients, drug-eluting stents are not good value for money, even if prices were substantially reduced. Drug-eluting stents are cost effective in patients needing small vessel or bypass graft stenting, but not in those who require large native vessel stenting.

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 technology is feasible and safe. In our opinion, the high radial resistive force and the advanced braided design with tight stent-strut interstices may be beneficial in terms of plaque stabilization. Further studies are necessary and warranted.« less

Treatment of cuff-related tracheal stenosis with a fully covered retrievable expandable metallic stent.

PubMed

Chen, G; Wang, Z; Liang, X; Wang, Y; Wang, Y; Wang, Z; Xian, J

2013-04-01

To investigate the clinical effectiveness, complications, and optimal duration of use of covered retrievable expandable metallic stents in the management of cuff-related tracheal stenosis. Twenty-one patients with cuff-related tracheal stenosis, Meyer-Cotton grade II (29%) and III (71%), who underwent fluoroscopically guided placement of covered retrievable expandable metallic stents were studied. Sixty-four-section computed tomography (CT) and bronchovideoscopy were performed prior to stent insertion, 1 month after stent insertion, in the case of stent-related complications, and after stent removal. Clinical manifestations, Hugh-Jones classification, and forced expiratory volume in 1 s (FEV1) were used to evaluate respiratory function before and after stent insertion and removal. The diameter of the stricture and FEV1 changes before insertion and after removal were analysed using the paired samples t-test. A p-value of ≤0.05 was considered statistically significant. Twenty-one patients had 27 covered retrievable expandable metallic stents placed. Stents were electively removed from 20 patients. The median duration of stent placement was 5 months (range 4-12 months). One stent was not removed due to mucopolysaccharidosis type II (MPS II or Hunter syndrome) with tracheomalacia. After stent removal, airway dimensions increased and airway occlusion was symptomatically relieved in all patients. CT and bronchovideoscopy showed patent lumens with increased dimensions. Stent-related complications occurred in 19 (91%) patients, including granulation tissue formation (n = 18, 86%), stent migration and stent expectoration (n = 2, 10%), mucus plugging (n = 1, 5%), and halitosis (n = 6, 29%). Some patients experienced multiple complications, which were all managed effectively while the stent was still in place. There was a statistically significant difference in the diameter of the stricture and FEV1 between the time of stent insertion and removal. An improvement in Hugh-Jones classification of greater than one grade was seen in patients after stent removal. Temporary placement of a fully covered retrievable expandable metallic stent is safe and effective in cuff-related tracheal stenosis. The optimal duration of stent placement may be 4-8 months. Copyright © 2012 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

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.

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.

[Eight Cases of Esophagus and Tracheobronchial Stenting for Advanced Esophageal Cancer].

PubMed

Nakahara, Yujiro; Takachi, Ko; Tsujimura, Naoto; Wakasugi, Masaki; Hirota, Masaki; Matsumoto, Takashi; Takemoto, Hiroyoshi; Nishioka, Kiyonori; Oshima, Satoshi

2017-11-01

Malignant stricture and fistula of the esophagus and tracheobronchus adversely affect the quality of life(QOL)in patients with advanced esophageal cancer. Stenting is one ofthe therapies available for these patients. We investigated the outcomes ofesophagus and tracheobronchial stenting in our institution. Eight patients with advanced esophageal cancer underwent double stenting from 2010 to 2016. Among them, 4 patients underwent double stenting as planned. One patient underwent an emergency tracheal stenting because ofstenosis ofthe trachea caused by esophageal stenting. Three patients underwent tracheobronchial stenting later on because ofan increase in the tumor size after esophageal stenting. Dysphagia score was improved in 5(67.5%)out ofthe 8 patients. Respiratory symptoms were improved in all patients, and 4 patients(50.0%) were discharged. The median survival time after esophageal stenting was 70.5 days. Esophagus and tracheobronchial stenting for advanced esophageal cancer was useful for the improvement of the QOL.

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

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.

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.

Timing of silicone stent removal in patients with post-tuberculosis bronchial stenosis.

PubMed

Eom, Jung Seop; Kim, Hojoong; Park, Hye Yun; Jeon, Kyeongman; Um, Sang-Won; Koh, Won-Jung; Suh, Gee Young; Chung, Man Pyo; Kwon, O Jung

2013-10-01

In patients with post-tuberculosis bronchial stenosis (PTBS), the severity of bronchial stenosis affects the restenosis rate after the silicone stent is removed. In PTBS patients with incomplete bronchial obstruction, who had a favorable prognosis, the timing of stent removal to ensure airway patency is not clear. We evaluated the time for silicone stent removal in patients with incomplete PTBS. A retrospective study examined PTBS patients who underwent stenting and removal of a silicone stent. Incomplete bronchial stenosis was defined as PTBS other than total bronchial obstruction, which had a luminal opening at the stenotic segment on bronchoscopic intervention. The duration of stenting was defined as the interval from stent insertion to removal. The study included 44 PTBS patients and the patients were grouped at intervals of 6 months according to the duration of stenting. Patients stented for more than 12 months had a significantly lower restenosis rate than those stented for less than 12 months (4% vs. 35%, P = 0.009). Multiple logistic regression revealed an association between stenting for more than 12 months and a low restenosis rate (odds ratio 12.095; 95% confidence interval 1.097-133.377). Moreover, no restenosis was observed in PTBS patients when the stent was placed more than 14 months previously. In patients with incomplete PTBS, stent placement for longer than 12 months reduced restenosis after stent removal.

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.

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.

The effect of stent graft oversizing on radial forces considering nitinol wire behavior and vessel characteristics.

PubMed

Senf, B; von Sachsen, S; Neugebauer, R; Drossel, W-G; Florek, H-J; Mohr, F W; Etz, C D

2014-11-01

Stent graft fixation in the vessel affects the success of endovascular aneurysm repair. Thereby the radial forces of the stent, which are dependent on several factors, play a significant role. In the presented work, a finite element sensitivity study was performed. The radial forces are 29% lower when using the hyperelastic approach for the vessel compared with linear elastic assumptions. Without the linear elastic modeled plaque, the difference increases to 35%. Modeling plaque with linear elastic material approach results in 8% higher forces than with a hyperelastic characteristic. The significant differences resulting from the investigated simplifications of the material lead to the conclusion that it is important to apply an anisotropic nonlinear approach for the vessel. The oversizing study shows that radial forces increase by 64% (0.54 N) when raising the oversize from 10 to 22%, and no further increase in force can be observed beyond these values (vessel diameter D=12 mm). Starting from an oversize of 24%, the radial force steadily decreases. The findings of the investigation show that besides the oversizing the material properties, the ring design and the vessel characteristics have an influence on radial forces. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

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 indication or location.

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.

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.

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 possible, and it is important to determine the risk factors involved in stent migration.

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

Airway stent complications: the role of follow-up bronchoscopy as a surveillance method

PubMed Central

Labaki, Wassim; Yu, Diana H.; Salwen, Benjamin; Gilbert, Christopher; Schneider, Andrea L. C.; Ortiz, Ricardo; Feller-Kopman, David; Arias, Sixto; Yarmus, Lonny

2017-01-01

Background Airway stenting has become an integral part of the therapeutic endoscopic management of obstructive benign and malignant central airway diseases. Despite increased use of airway stents and frequent stent-associated complications, no clear guidelines for surveillance and maintenance exist. This study aim is to elucidate predictive factors associated with development of stent complications, as well as an optimal surveillance period for follow-up bronchoscopy for early detection and possible prevention of stent-associated complications. Methods Retrospective cohort study of all patients who underwent airway stent placements at our institution from April 2010 to December 2013 for benign and malignant airway diseases. Metallic, silicone (straight, Y stent, T-tube) and hybrid stents were included in the study. Stent complications were analyzed at the time of follow-up bronchoscopy performed four to six weeks after initial stent placement or earlier if patients became symptomatic. Results The study included 134 patients of which 147 stents were placed. Follow-up bronchoscopy was performed in 94 patients. Symptomatic status at the time of follow-up bronchoscopy was not associated with stent complications [odds ratio (OR) =1.88; 95% CI: 0.79–4.45; P=0.15]. Patient age, sex, indication for stent placement, and stent location, were not associated with development of complications (all P>0.05). Compared to all other stents, hybrid stents were more likely to migrate (OR =6.60; 95% CI: 2.16–20.2; P=0.001) or obstruct by secretions (OR =2.53; 95% CI: 1.10–5.84; P=0.03). There were no complications associated with surveillance bronchoscopy. Conclusions Surveillance bronchoscopy within 4 to 6 weeks of stent placement may be useful for early detection of complications and their subsequent management, regardless of symptomatic status and indication for stent placement. Prospective multicenter studies are needed to compare optimal surveillance methods and the impact on patient mortality, morbidity and healthcare costs. PMID:29268534

Ureteral Stents and Foley Catheters-Associated Urinary Tract Infections: The Role of Coatings and Materials in Infection Prevention.

PubMed

Lo, Joey; Lange, Dirk; Chew, Ben H

2014-03-10

Urinary tract infections affect many patients, especially those who are admitted to hospital and receive a bladder catheter for drainage. Catheter associated urinary tract infections are some of the most common hospital infections and cost the health care system billions of dollars. Early removal is one of the mainstays of prevention as 100% of catheters become colonized. Patients with ureteral stents are also affected by infection and antibiotic therapy alone may not be the answer. We will review the current evidence on how to prevent infections of urinary biomaterials by using different coatings, new materials, and drug eluting technologies to decrease infection rates of ureteral stents and catheters.

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.

Endovascular revascularization for aortoiliac atherosclerotic disease

PubMed Central

Aggarwal, Vikas; Waldo, Stephen W; Armstrong, Ehrin J

2016-01-01

Atherosclerotic iliac artery disease is increasingly being treated with endovascular techniques. A number of new stent technologies can be utilized with high long-term patency, including self-expanding stents, balloon-expandable stents, and covered stents, but comparative data on these stent types and in more complex lesions are lacking. This article provides a review of currently available iliac stent technologies, as well as complex procedural aspects of iliac artery interventions, including approaches to the treatment of iliac bifurcation disease, long segment occlusions, choice of stent type, and treatment of iliac artery in-stent restenosis. PMID:27099509

Tracheal reaction to three different intraluminal stents in an animal model of tracheomalacia.

PubMed

Weinberg, Mark; Sandbank, Judith; Flumenblit, Yoseph; Klin, Baruch; Vinograd, Itzhak

2005-06-01

Three different internal airway stents were studied in an animal model of tracheomalacia: the Palmaz stent (Johnson & Johnson, Warren, New Jersey) and the NIR stent (Medinol Ltd., Tel Aviv, Israel)--both made of stainless steel in the form of tubular mesh--and the Nitinol stent, made of nickel-titanium formed into a spiral shape. All three stents could be adequately stabilized in the malacic tracheal segment. The Nitinol stent (Medinol Ltd., Tel Aviv, Israel) proved to be less reactive to the tracheal mucosa, demonstrated higher biocompatibility with significantly less granulation tissue formation, and showed superior radial resistance. Extraction of the Nitinol stent also proved to be much smoother. This stent may be the stent of choice in the treatment of tracheo- and bronchomalacia.

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

PubMed Central

Kawaguchi, Yoshiaki; Lin, Jung-Chun; Kawashima, Yohei; Maruno, Atsuko; Ito, Hiroyuki; Ogawa, Masami; Mine, Tetsuya

2015-01-01

Aim. To analyze the risk factors for pancreatic stent migration, dislocation, and fracture in chronic pancreatitis patients with pancreatic strictures. Materials and Methods. Endoscopic stent placements (total 386 times) were performed in 99 chronic pancreatitis patients with pancreatic duct stenosis at our institution between April 2006 and June 2014. We retrospectively examined the frequency of stent migration, dislocation, and fracture and analyzed the patient factors and stent factors. We also investigated the retrieval methods for migrated and fractured stents and their success rates. Results. The frequencies of stent migration, dislocation, and fracture were 1.5% (5/396), 0.8% (3/396), and 1.2% (4/396), respectively. No significant differences in the rates of migration, dislocation, or fracture were noted on the patient factors (etiology, cases undergoing endoscopic pancreatic sphincterotomy, location of pancreatic duct stenosis, existence of pancreatic stone, and approach from the main or minor papilla) and stent factors (duration of stent placement, numbers of stent placements, stent shape, diameter, and length). Stent retrieval was successful in all cases of migration. In cases of fractured stents, retrieval was successful in 2 of 4 cases. Conclusion. Stent migration, fracture, and dislocation are relatively rare, but possible complications. A good understanding of retrieval techniques is necessary. PMID:25945085

Efficacy and tolerance of a new silicone stent for the treatment of benign tracheal stenosis: preliminary results.

PubMed

Vergnon, J M; Costes, F; Polio, J C

2000-08-01

In inoperable patients with tracheal stenosis who are treated using silicone stents, stent migration occurs in 18.6% of cases. To decrease the migration rate, we have designed a new silicone stent with narrow central and larger distal parts. This study analyzes the stability and tolerance of this new stent. Preliminary prospective study conducted in two French university hospitals. Thirteen inoperable patients with benign complex tracheal stenosis due to intubation or tracheotomy. Tracheal stent insertion was performed under general anesthesia with a rigid bronchoscope. The patients were followed up clinically up to stent removal, which was planned at 18 months. Stent insertion or removal was very simple and did not differ from other silicone stents. No migration occurred after a mean follow-up of 22.8 months. Minimal granuloma formation occurred in only one patient (7.7%). Sputum retention remained similar to that with other silicone stents and could be improved by a smoother internal wall. Stents have been removed in seven patients after a mean duration of 19.6 months, with a complete stenosis cure in four cases. This new stent combines the excellent stability of the metallic stents and the tolerance and easy removal of straight silicone stents. This allows a prolonged use in order to obtain curative action.

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.

In Situ Fracture of Stents Implanted for Relief of Pulmonary Arterial Stenosis in Patients with Congenitally Malformed Hearts

PubMed Central

McElhinney, Doff B.; Bergersen, Lisa; Marshall, Audrey C.

2014-01-01

Background One of the most common uses of stents in patients with congenitally malformed hearts is treatment of pulmonary arterial stenosis. Although there are reports of fractured pulmonary arterial stents, little is known about the risk factors for, and implications of, such fractures. Methods We reviewed angiograms to identify fractures in stents previously inserted to relieve stenoses in pulmonary arteries from 1990 through 2001 in patients who also underwent follow-up catheterization at least 3 years after placement of the stent. We undertook matched cohort analysis, matching a ratio of 2 fractured to 1 unfractured stent. Results Overall, 166 stents meeting the criterions of our study had been placed in 120 patients. We identified fractures in 35 stents (21%) in 29 patients. All fractured stents were in the central pulmonary arteries, 24 (69%) in the central part of the right pulmonary artery, and all were complete axial fractures, or complex fractures along at least 2 planes. Stent-related factors associated with increased risk of fracture identified by multivariable logistic regression included placement in close apposition to the ascending aorta (p = 0.001), and a larger expanded diameter (p = 0.002). There was obstruction across 28 of 35 fractured stents, which was severe in 11. We re-stented 21 of the fractured stents, and recurrent fracture was later diagnosed in 3 of these. A fragment of the fractured stent embolized distally in 2 patients, without clinically important effects. Conclusions In situ fracture of pulmonary arterial stents is relatively common, and in most cases is related to compression by the aorta. There is usually recurrent obstruction across the fractured stent, but fractured stents rarely embolize, and are not associated with other significant complications. PMID:18559137

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

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.

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.

Adjunctive stent use during endovascular intervention to the femoropopliteal artery with drug coated balloons: Insights from the XLPAD registry.

PubMed

Kokkinidis, Damianos G; Jeon-Slaughter, Haekyung; Khalili, Houman; Brilakis, Emmanouil S; Shammas, Nicolas W; Banerjee, Subhash; Armstrong, Ehrin J

2018-06-01

With growing use of drug-coated balloons (DCB) for femoropopliteal (FP) artery interventions, there is limited information on rates of real-world adjunctive stent use and its association with short and long-term outcomes. We report on 225 DCB treated FP lesions in 224 patients from the Excellence in Peripheral Artery Disease (XLPAD) registry (NCT01904851) between 2014 and 2016. Cochran-Mantel-Haenszel and Wilcoxon rank sum statistics were used to compare stented (planned or 'bail-out') versus non-stented DCB treated lesions. Stents were implanted in 31% of FP DCB interventions. Among the 70 stents implanted, 46% were for 'bail-out' indications and 54% were planned. Lesions treated with stents were longer (mean 150 mm vs 100 mm; p < 0.001) and less likely to be in-stent restenosis lesions (10% vs 28%; p=0.003). Stenting was significantly more frequent in complex FP lesions, including chronic total occlusions (66% vs 34%; p < 0.001). For bail-out stenting, interwoven nitinol stents were the most common type (50%) followed by drug-eluting stents (34%) and bare-metal stents (22%). There were no differences in peri-procedural complication rates or 12-month target limb revascularization rates (18.6% vs 11.6%; p=0.162) or 12-month amputation rates (11.4% vs 11%; p=0.92) between lesions where adjunctive stenting was used versus lesions without adjunctive stenting, respectively. In conclusion, in a contemporary 'real-world' adjudicated multicenter US registry, adjunctive stenting was necessary in nearly a third of the lesions, primarily for the treatment of more complex FP lesions, with similar short and intermediate-term clinical outcomes compared with non-stented lesions.

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.

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

PubMed

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

2014-12-01

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

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.

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

Assessment of bio-safety of low-cost polyurethane urologic stents used in developing countries.

PubMed

Roy, Nobhojit; Waingankar, Santosh; Aggarwal, Gaurav

2012-04-01

Ureteral stents, despite their ubiquitous use, have not been evaluated for their safety and strength after removal from the patient. While literature is available from the industry with regards to manufacturing and specifications of stents, what happens to a stent after it is inserted into the body, still needs to be explored. We conducted a methodical study of 153 consecutive patients with urological problems who were stented with inexpensive polyurethane stents. Once removed from the patients, the stents were analyzed for breakload, tensile strength, elongation, pH, decomposition temperature, residue as well as diameter change. There was no significant change in the physical and mechanical properties of the stent after clinical use and the variance was within the acceptable range of biomaterials. There was minimal leaching of material and color change in all stents. The cheap polyurethane stents were found to be safe for use in patients, for the short time periods of in situ stenting. The degradation of physical and chemical properties of the stent was not significant. Thus it can be safely said that the stents currently in widespread use are cost-effective and physically safe for short spans of time.

Evaluation of XIENCE V everolimus-eluting and Taxus Express2 paclitaxel-eluting coronary stents in patients with jailed side branches from the SPIRIT IV trial at 2 years.

PubMed

Forrest, John K; Lansky, Alexandra J; Meller, Stephanie M; Hou, Liming; Sood, Poornima; Applegate, Robert J; Wang, John C; Skelding, Kimberly A; Shah, Aakar; Kereiakes, Dean J; Sudhir, Krishnankutty; Cristea, Ecaterina; Yaqub, Manejeh; Stone, Gregg W

2013-06-01

The aim of this study was to determine whether patients from the Clinical Evaluation of the XIENCE V Everolimus Eluting Coronary Stent System in the Treatment of Patients With de Novo Native Coronary Artery Lesions (SPIRIT) IV trial who underwent percutaneous coronary intervention, who had target lesions with jailed side branches, had improved clinical outcomes when treated with the XIENCE V versus Taxus Express(2) drug-eluting stent. In the SPIRIT III randomized trial, patients with target lesions with jailed side branches after XIENCE V compared with Taxus Express(2) implantation had lower 2-year rates of major adverse cardiac events. The SPIRIT IV trial represents a larger more diverse patient population compared with SPIRIT III. In the large-scale, prospective, multicenter, randomized SPIRIT IV trial, 3,687 patients who underwent coronary stenting with up to 3 de novo native coronary artery lesions were randomized 2:1 to receive XIENCE V versus Taxus Express(2) stents. Two-year clinical outcomes of patients with or without jailed side branches after stenting were compared. A jailed side branch was defined as any side branch >1.0 mm in diameter within the target segment being stented, excluding bifurcations deemed to require treatment. Of the 3,687 patients in SPIRIT IV, a total of 1,426 had side branches that were jailed during angioplasty of the target lesion. Patients with jailed side branches after XIENCE V compared with Taxus Express(2) implantation had significantly lower 2-year rates of target lesion failure (6.5% vs 11.9%, p = 0.001), major adverse cardiac events (6.6% vs 12.2%, p = 0.0008), ischemia-driven target vessel revascularization (4.1% vs 7.9%, p = 0.004), and stent thrombosis (0.6% vs 2.8%, p = 0.001). In conclusion, patients with jailed side branches after stenting with XIENCE V compared to Taxus Express(2) devices had superior clinical outcomes at 2 years in the large-scale randomized SPIRIT IV trial. Copyright © 2013 Elsevier Inc. All rights reserved.

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.

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.

A review on fracture prevention of stent in femoropopliteal artery

NASA Astrophysics Data System (ADS)

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

2017-01-01

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

Expert Opinion: Optimising Stent Deployment in Contemporary Practice: The Role of Intracoronary Imaging and Non-compliant Balloons.

PubMed

Seth, Ashok; Gupta, Sajal; Pratap Singh, Vivudh; Kumar, Vijay

2017-09-01

Final stent dimensions remain an important predictor of restenosis, target vessel revascularisation (TVR) and subacute stent thrombosis (ST), even in the drug-eluting stent (DES) era. Stent balloons are usually semi-compliant and thus even high-pressure inflation may not achieve uniform or optimal stent expansion. Post-dilatation with non-compliant (NC) balloons after stent deployment has been shown to enhance stent expansion and could reduce TVR and ST. Based on supporting evidence and in the absence of large prospective randomised outcome-based trials, post-dilatation with an NC balloon to achieve optimal stent expansion and maximal luminal area is a logical technical recommendation, particularly in complex lesion subsets.

Is early removal of prophylactic ureteric stents beneficial in live donor renal transplantation?

PubMed Central

Indu, K. N.; Lakshminarayana, G.; Anil, M.; Rajesh, R.; George, K.; Ginil, K.; Georgy, M.; Nair, B.; Sudhindran, S.; Appu, T.; Unni, V. N.; Sanjeevan, K. V.

2012-01-01

Prophylactic ureteric stenting has been shown to reduce ureteric leaks and collecting system obstruction following renal transplantation and is in widespread use. However, the optimal time for removal of ureteric stents after renal transplantation remains unclear. Aim of this study was to compare the result of early versus late removal of ureteric stents after kidney transplantation of the laparoscopically retrieved live related donor grafts. Eligible patients were live donor kidney transplant recipients with normal urinary tracts. All recipients underwent extravesical Lich–Gregoire ureteroneocystostomy over 4F/160 cm polyurethane double J stents by a uniform technique. They were randomized on seventh postoperative day for early removal of stents on postoperative day 7 (Group I), or for late removal on postoperative day 28 (Group II). The incidence of urinary tract infections, asymptomatic bacteriuria, and urological complications were compared. Between 2007 and 2009, 130 kidney transplants were performed at one centre of which 100 were enrolled for the study, and 50 each were randomized into the two groups. Donor and recipient age, sex, native renal disease, immunosupression, number of rejection episodes, and antirejection therapy were similar in the two groups. The occurrence of symptomatic urinary tract infection during the follow-up period of 6 months was significantly less in the early stent removal group [5 out of 50 (10%) in Group I, vs 50 out of 15 (30%) in Group II, P=0.02]. Asymptomatic bacteriuria was documented in 2 out of 50 (4%) in Group I and 4 out of 50 (8%) in Group II (P=0.3). There was no statistically significant difference in the rate of ureteric leak, ureteric obstruction, or hematuria in the two groups (P=1.0). We conclude that, in kidney transplant recipients of laparoscopically retrieved live donor grafts, early stent removal at the end of first week reduces the incidence of urinary tract infection without increasing the rate of urine leak or ureteric obstruction. PMID:23162271

CT Evaluation of Small-Diameter Coronary Artery Stents: Effect of an Integrated Circuit Detector with Iterative Reconstruction.

PubMed

Geyer, Lucas L; Glenn, G Russell; De Cecco, Carlo Nicola; Van Horn, Mark; Canstein, Christian; Silverman, Justin R; Krazinski, Aleksander W; Kemper, Jenny M; Bucher, Andreas; Ebersberger, Ullrich; Costello, Philip; Bamberg, Fabian; Schoepf, U Joseph

2015-09-01

To use suitable objective methods of analysis to assess the influence of the combination of an integrated-circuit computed tomographic (CT) detector and iterative reconstruction (IR) algorithms on the visualization of small (≤3-mm) coronary artery stents. By using a moving heart phantom, 18 data sets obtained from three coronary artery stents with small diameters were investigated. A second-generation dual-source CT system equipped with an integrated-circuit detector was used. Images were reconstructed with filtered back-projection (FBP) and IR at a section thickness of 0.75 mm (FBP75 and IR75, respectively) and IR at a section thickness of 0.50 mm (IR50). Multirow intensity profiles in Hounsfield units were modeled by using a sum-of-Gaussians fit to analyze in-plane image characteristics. Out-of-plane image characteristics were analyzed with z upslope of multicolumn intensity profiles in Hounsfield units. Statistical analysis was conducted with one-way analysis of variance and the Student t test. Independent of stent diameter and heart rate, IR75 resulted in significantly increased xy sharpness, signal-to-noise ratio, and contrast-to-noise ratio, as well as decreased blurring and noise compared with FBP75 (eg, 2.25-mm stent, 0 beats per minute; xy sharpness, 278.2 vs 252.3; signal-to-noise ratio, 46.6 vs 33.5; contrast-to-noise ratio, 26.0 vs 16.8; blurring, 1.4 vs 1.5; noise, 15.4 vs 21.2; all P < .001). In the z direction, the upslopes were substantially higher in the IR50 reconstructions (2.25-mm stent: IR50, 94.0; IR75, 53.1; and FBP75, 48.1; P < .001). The implementation of an integrated-circuit CT detector provides substantially sharper out-of-plane resolution of coronary artery stents at 0.5-mm section thickness, while the use of iterative image reconstruction mostly improves in-plane stent visualization.

Type IIIb Endoleak and Relining: A Mathematical Model of Distraction Forces.

PubMed

Swaelens, Charles; Poole, Robert J; Torella, Francesco; McWilliams, Richard G; England, Andrew; Fisher, Robert K

2016-04-01

To examine the changes in distraction force following relining of a conventional abdominal aortic stent-graft with a type IIIb endoleak using the Nellix endovascular sealing device compared to a unilateral stent-graft. Relining is often used to repair type IIIb endoleaks, but the consequences to graft stability are unknown. A mathematical model was constructed based on pressure and volume flow through the stent-grafts, incorporating recognized distraction force equations. Steady flow was presumed at peak systolic pressures to calculate the maximum distraction force, with gravity ignored. Distraction forces for 28- to 36-mm-diameter stent-graft bodies with 16-mm limbs were calculated and compared to forces following relining with single and double Nellix devices or the Renu unilateral device. Distraction forces for the 28-, 32-, and 36-mm stent-grafts prior to relining were 5.99, 10.21, and 14.99 N, respectively. Similar forces were reported after relining with bilateral Nellix devices (5.86, 10.08, and 14.86 N, respectively). However, use of a unilateral Nellix increased the distraction forces to 9.92, 14.14, and 18.92 N, respectively. These were comparable to the increase observed after relining with a Renu unilateral stent-graft (9.87, 14.09, and 18.86 N, respectively). The proportional increase in distraction force for a unilateral relining ranged from 26% to 66%, with the greatest increase noted in the smaller diameter main bodies. Relining a stent-graft with a type IIIb endoleak using bilateral Nellix devices does not increase the distraction force. However, a unilateral Nellix device or the Renu system could theoretically increase the distraction force by up to 66%, potentially risking migration and type Ia endoleak. In clinical practice, these results suggest that a relining with bilateral Nellix may have benefits over the Renu unilateral stent-graft. © The Author(s) 2016.

In vitro Dosimetric Study of Biliary Stent Loaded with Radioactive 125I Seeds

PubMed Central

Yao, Li-Hong; Wang, Jun-Jie; Shang, Charles; Jiang, Ping; Lin, Lei; Sun, Hai-Tao; Liu, Lu; Liu, Hao; He, Di; Yang, Rui-Jie

2017-01-01

Background: A novel radioactive 125I seed-loaded biliary stent has been used for patients with malignant biliary obstruction. However, the dosimetric characteristics of the stents remain unclear. Therefore, we aimed to describe the dosimetry of the stents of different lengths — with different number as well as activities of 125I seeds. Methods: The radiation dosimetry of three representative radioactive stent models was evaluated using a treatment planning system (TPS), thermoluminescent dosimeter (TLD) measurements, and Monte Carlo (MC) simulations. In the process of TPS calculation and TLD measurement, two different water-equivalent phantoms were designed to obtain cumulative radial dose distribution. Calibration procedures using TLD in the designed phantom were also conducted. MC simulations were performed using the Monte Carlo N-Particle eXtended version 2.5 general purpose code to calculate the radioactive stent's three-dimensional dose rate distribution in liquid water. Analysis of covariance was used to examine the factors influencing radial dose distribution of the radioactive stent. Results: The maximum reduction in cumulative radial dose was 26% when the seed activity changed from 0.5 mCi to 0.4 mCi for the same length of radioactive stents. The TLD's dose response in the range of 0–10 mGy irradiation by 137Cs γ-ray was linear: y = 182225x − 6651.9 (R2= 0.99152; y is the irradiation dose in mGy, x is the TLDs’ reading in nC). When TLDs were irradiated by different energy radiation sources to a dose of 1 mGy, reading of TLDs was different. Doses at a distance of 0.1 cm from the three stents’ surface simulated by MC were 79, 93, and 97 Gy. Conclusions: TPS calculation, TLD measurement, and MC simulation were performed and were found to be in good agreement. Although the whole experiment was conducted in water-equivalent phantom, data in our evaluation may provide a theoretical basis for dosimetry for the clinical application. PMID:28469106

Low-profile stent placement with the monorail technique for treatment of renal artery stenosis: midterm results of a prospective trial.

PubMed

Müller-Hülsbeck, Stefan; Frahm, Christian; Behm, Charlotte; Schäfer, Phillip Jobst; Bolte, Hendrik; Heller, Martin; Jahnke, Thomas

2005-07-01

To determine feasibility, safety, and midterm patency of a monorail balloon stent device for the treatment of renal artery stenosis (RAS). During a period of 30 months, 47 patients (with severe hypertension, n=45; renal insufficiency, n=20) with 50 cases of RAS and indications for stent implantation (calcified ostial lesion, n=41; insufficient percutaneous transluminal angioplasty, n=6; dissection, n=3) were enrolled into the prospective evaluation. After predilation, 59 stents (Rx-Herculink 4 mm, n=2; 5 mm, n=19; 6 mm, n=35; 7 mm, n=3) were implanted under manometer control with use of the long-sheath technique (5 F; 6 F for 7-mm stents) via a femoral (n=44) or transbrachial approach (n=6). Parameters of hypertension and renal insufficiency were determined before and after the procedure and for a maximum of 18 months. Restenosis rate was determined with color duplex ultrasonography. Renal artery stent placement (mean diameter, 5.7 mm; mean length, 16 mm) was technically successful in all cases (100%). Mean blood pressure and serum creatinine level decreased from 177/93 mm Hg to 145/78 mm Hg and from 1.8 mg/dL to 1.5 mg/dL, respectively. Within 48 hours after the implantation, acute occlusions occurred in two patients, supposedly triggered by cholesterol embolization. Primary and primary assisted patency rates were 87% and 92% at 6 months and 75% and 84% at 18 months. Renal artery stent placement with the rapid-exchange monorail system is a safe procedure with promising patency rates. In combination with the long-sheath technique, adequate control of stent deployment is guaranteed during the entire intervention. The low profile of the device facilitates the use of small sheaths (5 F) to minimize access-site complications.

Comparison between uncovered and covered self-expandable metal stent placement in malignant duodenal obstruction.

PubMed

Kim, Ji Won; Jeong, Ji Bong; Lee, Kook Lae; Kim, Byeong Gwan; Ahn, Dong Won; Lee, Jae Kyung; Kim, Su Hwan

2015-02-07

To compare the clinical outcomes of uncovered and covered self-expandable metal stent placements in patients with malignant duodenal obstruction. A total of 67 patients were retrospectively enrolled from January 2003 to June 2013. All patients had symptomatic obstruction characterized by nausea, vomiting, reduced oral intake, and weight loss. The exclusion criteria included asymptomatic duodenal obstruction, perforation or peritonitis, concomitant small bowel obstruction, or duodenal obstruction caused by benign strictures. The technical and clinical success rate, complication rate, and stent patency were compared according to the placement of uncovered (n = 38) or covered (n = 29) stents. The technical and clinical success rates did not differ between the uncovered and covered stent groups (100% vs 96.6% and 89.5% vs 82.8%). There were no differences in the overall complication rates between the uncovered and covered stent groups (31.6% vs 41.4%). However, stent migration occurred more frequently with covered than uncovered stents [20.7% (6/29) vs 0% (0/38), P < 0.05]. Moreover, the overall cumulative median duration of stent patency was longer in uncovered than in covered stents [251 d (95%CI: 149.8 d-352.2 d) vs 139 d (95%CI: 45.5 d-232.5 d), P < 0.05 by log-rank test] The overall cumulative median survival period was not different between the uncovered stent (70 d) and covered stent groups (60 d). Uncovered stents may be preferable in malignant duodenal obstruction because of their greater resistance to stent migration and longer stent patency than covered stents.

Comparison between uncovered and covered self-expandable metal stent placement in malignant duodenal obstruction

PubMed Central

Kim, Ji Won; Jeong, Ji Bong; Lee, Kook Lae; Kim, Byeong Gwan; Ahn, Dong Won; Lee, Jae Kyung; Kim, Su Hwan

2015-01-01

AIM: To compare the clinical outcomes of uncovered and covered self-expandable metal stent placements in patients with malignant duodenal obstruction. METHODS: A total of 67 patients were retrospectively enrolled from January 2003 to June 2013. All patients had symptomatic obstruction characterized by nausea, vomiting, reduced oral intake, and weight loss. The exclusion criteria included asymptomatic duodenal obstruction, perforation or peritonitis, concomitant small bowel obstruction, or duodenal obstruction caused by benign strictures. The technical and clinical success rate, complication rate, and stent patency were compared according to the placement of uncovered (n = 38) or covered (n = 29) stents. RESULTS: The technical and clinical success rates did not differ between the uncovered and covered stent groups (100% vs 96.6% and 89.5% vs 82.8%). There were no differences in the overall complication rates between the uncovered and covered stent groups (31.6% vs 41.4%). However, stent migration occurred more frequently with covered than uncovered stents [20.7% (6/29) vs 0% (0/38), P < 0.05]. Moreover, the overall cumulative median duration of stent patency was longer in uncovered than in covered stents [251 d (95%CI: 149.8 d-352.2 d) vs 139 d (95%CI: 45.5 d-232.5 d), P < 0.05 by log-rank test] The overall cumulative median survival period was not different between the uncovered stent (70 d) and covered stent groups (60 d). CONCLUSION: Uncovered stents may be preferable in malignant duodenal obstruction because of their greater resistance to stent migration and longer stent patency than covered stents. PMID:25663777

Evaluation of symptoms and patients' comfort for JJ-ureteral stents with and without antireflux-membrane valve.

PubMed

Ecke, Thorsten H; Bartel, Peter; Hallmann, Steffen; Ruttloff, Jürgen

2010-01-01

To evaluate safety and patients' comfort by using the ureteral stent symptom questionnaire. Ureteral stents are used to provide upper urinary-tract drainage. A total of 133 JJ-ureteral stents with and without antireflux-membrane valve as consecutive referrals for therapy of hydronephrosis have been inserted. Four weeks after insertion of the ureteral stent, the patients were asked about pain while urination, flank pain due to reflux, and the comparison with former stents. Ultrasound of the kidney for hydronephrosis grade and creatinine value as follow-up have been documented. Statistical analysis included chi(2) test after Pearson correlation computed and performed by SPSS software. We found a high correlation between the JJ-ureteral stent used and the detection of a hydronephrosis (P = .004). More patients who had a JJ-ureteral stent without valve complained of flank pain (P <.0005) and pain in the bladder (P <.0005). Patients who had a ureteral stent before were asked to compare new stents with the former ones. No patients with a JJ-ureteral stent with valve found this one to be worse than what they had before. JJ-stent related symptoms are a major problem for these patients. New stent designs and materials will be developed in the future to reduce stent-related morbidity and improve patient comfort. JJ-ureteral stents with an antireflux-membrane valve have a lower complication rate and provide a higher patient comfort compared with stents without valve. Crown Copyright 2010. Published by Elsevier Inc. All rights reserved.

Rare Esophageal Migration of AXIOS Stent Used for Walled-off Pancreatic Necrosis Drainage

PubMed Central

Renno, Anas; Hammad, Tariq; Nawras, Ali

2017-01-01

The AXIOS stent (Boston Scientific, Marlborough, MA) is a novel lumen-apposing self-expandable metallic stent designed for enteric drainage of nonadherent lumens. Efficacy and safety of using the AXIOS stent for pancreatic fluid drainage have been consistently shown in several studies. Although it is less common with this novel stent, stent migration still may happen. We present a case of AXIOS stent migration into the esophagus. PMID:28584846

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.

Comparison of covered versus uncovered wire mesh stents in the canine biliary tract.

PubMed

Silvis, S E; Sievert, C E; Vennes, J A; Abeyta, B K; Brennecke, L H

1994-01-01

Self-expanding wire mesh stents have been developed for endoscopic placement across malignant biliary strictures, but tumor ingrowth may limit the usefulness of open mesh stents. We reasoned that coating the wire mesh might prevent tumor ingrowth. Tissue response to covered and uncovered stents was compared in dogs. Stents were surgically placed in the bile ducts of 22 mongrel dogs through the sphincter of Oddi. Either a silicone-covered stent or an uncovered stent was inserted. Liver function test values remained normal throughout a 1- or 3-month study. Necropsy revealed that all ducts were unobstructed. Bile duct histologic examination revealed mild-to-moderate cellular infiltration in all animals. Mucosal hyperplasia was more marked in the animals with uncovered stents and the bare wires became deeply embedded in bile duct epithelium, whereas the wires of covered stents did not. We conclude that covered stents are well tolerated by the canine bile duct. These results suggest that such stents may be removable, making self-expanding metal stents an appropriate treatment for both benign and malignant biliary strictures.

Difficult removal of fully covered self expandable metal stents (SEMS) for benign biliary strictures: the "SEMS in SEMS" technique.

PubMed

Tringali, Andrea; Blero, Daniel; Boškoski, Ivo; Familiari, Pietro; Perri, Vincenzo; Devière, Jacques; Costamagna, Guido

2014-06-01

Removal of biliary Fully Covered Self Expandable Metal Stents can fail due to stent migration and/or hyperplastic ingrowth/overgrowth. A case series of 5 patients with benign biliary strictures (2 post-cholecystectomy, 2 following liver transplantation and 1 related to chronic pancreatitis) is reported. The biliary stricture was treated by temporary insertion of Fully Covered Self Expandable Metal Stents. Stent removal failed due to proximal stent migration and/or overgrowth. Metal stent removal was attempted a few weeks after the insertion of another Fully Covered Metal Stent into the first one. The inner Fully Covered Self Expandable Metal Stent compressed the hyperplastic tissue, leading to the extraction of both the stents in all cases. Two complications were reported as a result of the attempt to stents removal (mild pancreatitis and self-limited haemobilia). In the present series, the "SEMS in SEMS" technique revealed to be effective when difficulties are encountered during Fully Covered Self Expandable Metal Stents removal. Copyright © 2014 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Experimental Percutaneous Extrahepatic Portacaval Shunt Creation by Transjugular Approach in Swine

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

Seong, Chang Kyu; Pavcnik, Dusan, E-mail: pavcnikd@ohsu.edu; Uchida, Barry T.

2005-06-15

The purpose of the study was to evaluate the feasibility of the creation of a percutaneous extrahepatic portacaval shunt (PEPS) in swine by a transjugular approach and to find a suitable stent-graft to use in PEPS. In 12 swine, the extrahepatic portal vein (PV) was entered from the inferior vena cava (IVC) by a needle system introduced from the transjugular approach. A catheter introduced through the transhepatic approach served as a target. Five types of stent-graft consisting of homemade Z stents and a polytetrafluoethylene cover were explored for PEPS creation. Eight animals had follow-up venograms up to 6 weeks ormore » until the shunt became severely stenotic. Gross and histologic examinations were performed after the final follow-up venography. The PV punctures and stent-graft placement were difficult, but the PEPS was established in all animals. In four animals, the stent-graft failed to adequately cover the tract, causing severe hemorrhage. Only two shunts remained patent up to 6 weeks. The other shunts exhibited severe stenosis or occlusion. At gross examination, all shunts traversed the liver parenchyma of the caudate lobe surrounding the IVC. The extravascular PEPS portion was 4 mm to 2 cm long. All shunts entered the PV close to the splenomesenteric junction and exhibited neointimal formation. Shunt stenoses were caused by neointimal hyperplasia and occlusions by a superimposed thrombus. PEPS can be created by the transjugular approach in swine, but only the PV shunt entrance is extrahepatic. None of the tested rigid stent-grafts were suitable for PEPS creation. A short flexible stent-graft with flanged ends is suggested for further exploration.« less

Timing of silicone stent removal in patients with post-tuberculosis bronchial stenosis

PubMed Central

Eom, Jung Seop; Kim, Hojoong; Park, Hye Yun; Jeon, Kyeongman; Um, Sang-Won; Koh, Won-Jung; Suh, Gee Young; Chung, Man Pyo; Kwon, O. Jung

2013-01-01

CONTEXT: In patients with post-tuberculosis bronchial stenosis (PTBS), the severity of bronchial stenosis affects the restenosis rate after the silicone stent is removed. In PTBS patients with incomplete bronchial obstruction, who had a favorable prognosis, the timing of stent removal to ensure airway patency is not clear. AIMS: We evaluated the time for silicone stent removal in patients with incomplete PTBS. SETTINGS AND DESIGN: A retrospective study examined PTBS patients who underwent stenting and removal of a silicone stent. METHODS: Incomplete bronchial stenosis was defined as PTBS other than total bronchial obstruction, which had a luminal opening at the stenotic segment on bronchoscopic intervention. The duration of stenting was defined as the interval from stent insertion to removal. The study included 44 PTBS patients and the patients were grouped at intervals of 6 months according to the duration of stenting. RESULTS: Patients stented for more than 12 months had a significantly lower restenosis rate than those stented for less than 12 months (4% vs. 35%, P = 0.009). Multiple logistic regression revealed an association between stenting for more than 12 months and a low restenosis rate (odds ratio 12.095; 95% confidence interval 1.097-133.377). Moreover, no restenosis was observed in PTBS patients when the stent was placed more than 14 months previously. CONCLUSIONS: In patients with incomplete PTBS, stent placement for longer than 12 months reduced restenosis after stent removal. PMID:24250736

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.

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.

[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.

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

Use of a retrievable metallic stent internally coated with silicone to treat airway obstruction.

PubMed

Kim, Jin Hyoung; Shin, Ji Hoon; Song, Ho-Young; Lee, Se Chul; Kim, Kyung Rae; Park, Jung-Hoon

2008-08-01

The authors hypothesized that internally covered stents can reduce the rates of stent migration or mucous retention. The authors performed this study to report their experience with use of a retrievable metallic stent internally coated with silicone in patients with benign or malignant central airway obstructions. From 2004 to 2007, the authors performed fluoroscopically guided placement of a retrievable metallic stent internally coated with silicone in 26 consecutive patients with benign (n = 5) and malignant (n = 21) central airway obstructions. Stents were woven from a single thread of a 0.2-mm-diameter nitinol wire in a tubular configuration and internally covered with silicone membrane. Stent placement was technically and clinically successful in 93% (25/26) and 85% (22/26) of the patients, respectively. There were eight complications (31%) after stent placement, including tumor overgrowth (n = 2), stent migration (n = 1), symptomatic granulation tissue formation (n = 1), severe pain (n = 1), improper stent location (n = 1), symptomatic sputum retention (n = 1) and esophagobronchial fistula (n = 1). Because of complications, five stents were removed with a retrieval hook under fluoroscopic guidance without difficulty. The median survival period and stent patency were 150.0 days +/- 91.4 and 143.0 days +/- 26.7, respectively. The use of a retrievable metallic stent internally coated with silicone is a safe and effective method for relieving dyspnea, with adequate stent patency in patients with benign or malignant central airway obstructions. This stent design seems to be less prone to migration or mucous retention.

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.

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.

Fully covered self-expandable metal stents (SEMS), partially covered SEMS and self-expandable plastic stents for the treatment of benign esophageal ruptures and anastomotic leaks.

PubMed

van Boeckel, Petra G A; Dua, Kulwinder S; Weusten, Bas L A M; Schmits, Ruben J H; Surapaneni, Naveen; Timmer, Robin; Vleggaar, Frank P; Siersema, Peter D

2012-02-29

Benign esophageal ruptures and anastomotic leaks are life-threatening conditions that are often treated surgically. Recently, placement of partially and fully covered metal or plastic stents has emerged as a minimally invasive treatment option. We aimed to determine the clinical effectiveness of covered stent placement for the treatment of esophageal ruptures and anastomotic leaks with special emphasis on different stent designs. Consecutive patients who underwent placement of a fully covered self-expandable metal stent (FSEMS), a partially covered SEMS (PSEMS) or a self-expanding plastic stent (SEPS) for a benign esophageal rupture or anastomotic leak after upper gastrointestinal surgery in the period 2007-2010 were included. Data on patient demographics, type of lesion, stent placement and removal, clinical success and complications were collected A total of 52 patients received 83 esophageal stents (61 PSEMS, 15 FSEMS, 7 SEPS) for an anastomotic leak (n=32), iatrogenic rupture (n=13), Boerhaave's syndrome (n=4) or other cause (n=3). Endoscopic stent removal was successful in all but eight patients treated with a PSEMS due to tissue ingrowth. Clinical success was achieved in 34 (76%, intention-to-treat: 65%) patients (PSEMS: 73%, FSEMS: 83%, SEPS: 83%) after a median of 1 (range 1-5) stent and a median stenting time of 39 (range 7-120) days. In total, 33 complications in 24 (46%) patients occurred (tissue in- or overgrowth (n=8), stent migration (n=10), ruptured stent cover (all Ultraflex; n=6), food obstruction (n=3), severe pain (n=2), esophageal rupture (n=2), hemorrhage (n=2)). One (2%) patient died of a stent-related cause. Covered stents placed for a period of 5-6 weeks may well be an alternative to surgery for treating benign esophageal ruptures or anastomotic leaks. As efficacy between PSEMS, FSEMS and SEPS is not different, stent choice should depend on expected risks of stent migration (SEPS and FSEMS) and tissue in- or overgrowth (PSEMS).

Posterior Wall Capture and Femoral Artery Stenosis Following Use of StarClose Closing Device: Diagnosis and Therapy

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

Stefanczyk, Ludomir; Elgalal, Marcin T., E-mail: telgalal@yahoo.co.uk; Szubert, Wojciech

2013-10-15

A case of femoral artery obstruction following application of a StarClose type arterial puncture closing device (APCD) is presented. Ultrasonographic and angiographic imaging of this complication was obtained. The posterior wall of the vessel was accidentally caught in the anchoring element of the nitinol clip. This complication was successfully resolved by endovascular treatment and the implantation of a stent.

Immersed boundary peridynamics (IB/PD) method to simulate aortic dissection

NASA Astrophysics Data System (ADS)

Bhalla, Amneet Pal Singh; Griffith, Boyce

2016-11-01

Aortic dissection occurs when an intimal tear in the aortic wall propagates into the media to form a false lumen within the vessel wall. Rupture of the false lumen and collapse of the true lumen both carry a high risk of morbidity and mortality. Surgical treatment consists of either replacement of a portion of the aorta, or stent implantation to cover the affected segment. Both approaches carry significant risks: open surgical intervention is highly invasive, whereas stents can be challenging to implant and offer unclear long-term patient outcomes. It is also difficult to time optimally the intervention to ensure that the benefits of treatment outweigh its risks. In this work we develop innovative fluid-structure interaction (FSI) model combining elements from immersed boundary (IB) and peridynamics (PD) methods to simulate tears in membranes. The new approach is termed as IB/PD method. We use non-ordinary state based PD to represent material hyperelasticity. Several test problems are taken to validate peridynamics approach to model structural dynamics, with and without accounting for failure in the structures. FSI simulations using IB/PD method are compared with immersed finite element method (IB/FE) to validate the new hybrid approach. NIH Award R01HL117163 NSF Award ACI 1450327.

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.

In vivo evaluation of a new bioabsorbable self-expanding biliary stent.

PubMed

Ginsberg, Gregory; Cope, Constantin; Shah, Janak; Martin, Tanisha; Carty, Anthony; Habecker, Perry; Kaufmann, Carol; Clerc, Claude; Nuutinen, Juha-Pekka; Törmälä, Pertti

2003-11-01

Bioabsorbable stents may offer advantages for the treatment of benign and malignant biliary strictures, including large stent diameter, decreased biofilm accumulation and proliferative changes, elimination of the need for stent removal and imaging artifacts, and prospects for drug impregnation. However, suboptimal expansion has hampered prior iterations. A new bioabsorbable biliary stent (BioStent) was evaluated in a porcine model. BioStents were placed in 8 animals for long-term follow-up. The following were evaluated: accuracy and ease of delivery and deployment, radial expansion, and radiologic visualization. Stent function and biotolerance were assessed by cholangiography, serum bilirubin, and necropsy for histopathology performed in pairs at 2, 4, 6, and 12 months. Stents were delivered without sphincterotomy and were deployed easily, accurately, and with good immediate stent expansion and radiographic visualization. On follow-up, all stents were fully expanded and serum bilirubin levels remained within the normal range. Although there was no clinical evidence of biliary obstruction, filling defects were common at cholangiography. On histopathologic evaluation, there was neither bile duct integration or proliferative change. The BioStent bioabsorbable biliary stent, modified with axial runners, can be effectively deployed endoscopically, is self-expanding, is visualized radiographically, and remains patent up to 6 months. There was no bile duct integration or proliferative change, which are potential advantages. Stent occlusion and migration remain concerns.

Plastic or metal stents for benign extrahepatic biliary strictures: a systematic review

PubMed Central

2009-01-01

Background Benign biliary strictures may be a consequence of surgical procedures, chronic pancreatitis or iatrogenic injuries to the ampulla. Stents are increasingly being used for this indication, however it is not completely clear which stent type should be preferred. Methods A systematic review on stent placement for benign extrahepatic biliary strictures was performed after searching PubMed and EMBASE databases. Data were pooled and evaluated for technical success, clinical success and complications. Results In total, 47 studies (1116 patients) on outcome of stent placement were identified. No randomized controlled trials (RCTs), one non-randomized comparative studies and 46 case series were found. Technical success was 98,9% for uncovered self-expandable metal stents (uSEMS), 94,8% for single plastic stents and 94,0% for multiple plastic stents. Overall clinical success rate was highest for placement of multiple plastic stents (94,3%) followed by uSEMS (79,5%) and single plastic stents (59.6%). Complications occurred more frequently with uSEMS (39.5%) compared with single plastic stents (36.0%) and multiple plastic stents (20,3%). Conclusion Based on clinical success and risk of complications, placement of multiple plastic stents is currently the best choice. The evolving role of cSEMS placement as a more patient friendly and cost effective treatment for benign biliary strictures needs further elucidation. There is a need for RCTs comparing different stent types for this indication. PMID:20017920

Elastic Deformation Properties of Implanted Endobronchial Wire Stents in Benign and Malignant Bronchial Disease: A Radiographic In Vivo Evaluation

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

Hautmann, Hubert; Rieger, Johannes; Huber, Rudolf M.

1999-03-15

Purpose: To evaluate the long-term mechanical behavior in vivo of expandable endobronchial wire stents, we imaged three different prostheses in the treatment of tracheobronchial disease. Methods: Six patients with bronchial stenoses (three benign, three malignant) underwent insertion of metallic stents. Two self-expandable Wallstents, two balloon-expandable tantalum Strecker stents and two self-expandable nitinol Accuflex stents were used. Measurements of deformation properties were performed during voluntary cough by means of fluoroscopy, at 1 month and 7-10 months after implantation. The procedures were videotaped, their images digitized and the narrowing of stent diameters calculated at intervals of 20 msec. Results: After stent implantationmore » all patients improved with respect to ventilatory function. Radial stent narrowing during cough reached 53% (Wallstent), 59% (tantalum Strecker stent), and 52% (nitinol Accuflex stent) of the relaxed post-implantation diameter. Stent compression was more marked in benign compared with malignant stenoses. In the long term permanent deformation occurred with the tantalum Strecker stents; the other stents were unchanged. Conclusion: Endobronchial wire stents can be helpful in the treatment of major airway collapse and obstructing bronchial lesions. However, evidence of material fatigue as a possible effect of exposure to recurrent mechanical stress on the flexible mesh tube may limit their long-term use. This seems to be predominantly important in benign bronchial collapse.« less

[Assessment of the course of ischemic heart disease after placement of stents with drug covering and uncovered metal stents: data of 3 years follow-up].

PubMed

Buza, V V; Karpov, Iu A; Samko, A N; Deev, A D; Lopukhova, V V; Levitskiĭ, I V; Sozykin, A V

2009-01-01

The placement of sirolimus-eluting stents decreases the frequency of repeat revascularization procedures in patients undergoing percutaneous coronary intervention (PCI) in randomized clinical trials. However, there is uncertainty about the effectiveness of sirolimus-eluting stents, and increasing concern about their safety in routine clinical practice. From the prof. Samko PCI laboratory in Moscow, Russia, we identified 426 patients, who received either bare-metal stents alone or sirolimus-eluting stents alone during an index PCI procedure between March 1, 2002, and September 31, 2004.The primary outcomes of the study were the rates of target-lesion revascularization, myocardial infarction, death, late stent thrombosis. The 3-year rate of target-lesion revascularization was significantly lower among patients who received sirolimus-eluting stents than among those who received bare-metal stents (3.1% vs. 19 %, p=0.001). The 3-year mortality rate was not different between the bare-metal stent group and the sirolimus eluting stent group (5.9% vs. 7.2%, p=0.68), the 3-year rate of all ARC late stent thrombosis was similar in the two groups (5.9% and 7.2%, respectively; p=0.95). Sirolimus-eluting stents are effective in reducing the need for target-vessel revascularization without significantly increased rates of death, late stent thrombosis, myocardial infarction.

Are there fewer complications with third generation endografts in endovascular aneurysm repair?

PubMed

Jayia, P; Constantinou, J; Morgan-Rowe, L; Schroeder, T V; Lonn, L; Ivancev, K

2013-02-01

Endovascular aneurysm repair (EVAR) is widely accepted as a safe technique for treatment of aortic diseases since the concept was first pioneered by Volodos in 1986 and Parodi in 1991. Numerous registries have shown that this minimally invasive technique is associated with lower mortality when compared to open surgery in short and mid-term follow-up. The first pioneer devices had a high failure rate due to stent migration. This led to the creation of the first generation stent-grafts, which were associated with complications such as thrombosis of the limbs, graft migration and major endoleaks. The majority of these endostents are now withdrawn from the commercial market. However, these patients need lifelong surveillance because of a considerable risk of late complications. The materials used in the stent-graft vary with each manufacturer. Low porous fabric, suprarenal fixation and low profile devices led to the development of the second generation stent-grafts. The improvements with regards to the delivery systems, enabled reposition of the top-stent following deployment in some devices. The number of devices commercially available increased with the second generation. The third generation of stent-grafts, allowed treatment of complex aortic disease. Custom made solutions incorporate small openings, fenestrations for vessels involved in the aneurysmal disease and is already built in today's technology and available as CE marked devices. The device can be built with combinations of various branches and fenestrations in order to best accommodate the aortic anatomy of the patient. However, many issues remain with the development of this technology. There is a need for durable systems with less complicated deployment mechanics in order to be applied and more widespread. In conclusion, the third generation endografts in challenging anatomy has yielded encouraging results. With regards to short and midterm outcome and need for secondary interventions, evaluations shows comparable results with all devices performing well.

[Interventional radiology in treatment of biliodigestive anastomoses strictures].

PubMed

Okhotnikov, O I; Yakovleva, M V; Grigoriev, S N

2016-01-01

To analyze efficacy of interventional methods via antegrade transhepatic approach in treatment of patients with strictures of biliodigestive anastomoses. 24 patients aged 47.2 years were treated for the period 2002-2015. Average time from extrahepatic biliary reconstruction using transhepatic stented tubes to strictures appearance varied from 9 months to 12 years. One- and double-sided percutaneous transhepatic cholangiostomy was performed to abort biliary hypertension. Stricture recanalization was achieved using «catheter-wire» system. Antegrade dilatation of stricture was made using balloon catheter 8 mm and pressure up to 6 atm and stage exposition up to 10 minutes. Balloon repair of anastomosis was supplemented by stented outer-inner drainage of the area of stricture. Restoration of patency of stricture area using antegrade interventional methods was effective in 22 patients. Recurrent stricture occurred in 2 cases within 1.5 years that required repeated biliary reconstruction including antegrade extraction of blocked uncovered stent in 1 patient. There were no major postoperative complications and deaths. Maximal recurrence-free follow-up after stent installation was 11 years.

A direct method for fabricating tongue-shielding stent.

PubMed

Wang, R R; Olmsted, L W

1995-08-01

During oral cancer radiotherapy, a tongue-shielding radiation stent guides the patient's upper and lower jaws to a repeatable position, attenuates radiation doses, and protects the tongue and structures adjacent to the irradiated field. Conventionally, a tongue-shielding radiation stent is made of heat-cured polymethyl methacrylate resin in which a low-melting Pb-Bi-Sn alloy is embedded as a shielding layer. Its use involves multiple and lengthy clinical and laboratory procedures. An improved polyvinyl siloxane-metal composite shielding system for radioprotection has recently been developed. This two-component, base and catalyst, putty material offers a shielding effect similar to that of the conventional shielding alloys. Its major advantages are that it is simple to use, requires only one clinical appointment, and affords efficient collaboration between dental and medical teams during cancer treatment. This article describes a simplified direct method of fabricating a tongue-shielding stent with the use of a new polyvinylsiloxane-metal composite in conjunction with impression putty material.

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.

75 FR 54637 - Guidance for Industry and Food and Drug Administration Staff; Class II Special Controls Guidance...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-09-08

... infarction, treatment of in-stent restenosis and/or post-deployment stent expansion. Cutting/scoring PTCA... of in-stent restenosis and/or post- deployment stent expansion, be reclassified from class III to... PTCA catheters for the treatment of in-stent restenosis and/or post-deployment stent expansion, but not...

Very late stent thrombosis after sole stent-assisted coiling at the paraclinoid giant aneurysm : could prophylactic antiplatelet therapy be ceased at the only 1 year after procedure?

PubMed

Shin, Jung-Hoon; Park, Seong-Ho; Kim, Chang-Hyun; Lee, Chang-Young

2014-10-01

Stent thrombosis is a major limitation of stent-assisted coiling, which is an effective method for treating wide-necked aneurysms. Although early in-stent thrombosis has been reported, very late stent thrombosis (VLST) (>1 year) has not been reported following implantation of a single self-expandable stent designed for coiling. Herein, the authors present a case of VLST that occurred 14 months after single stent implantation in a large paraclinoid aneurysm with an ultra-wide neck involving the parent artery circumferentially. This case indicates the need for establishing guidelines regarding the optimal duration of prophylactic antiplatelet therapy following stent-assisted coiling, which remains undefined in the neuroendovascular field.

Assessment of In-Stent Restenosis Using 64-MDCT: Analysis of the CORE-64 Multicenter International Trial

PubMed Central

Wykrzykowska, Joanna J.; Arbab-Zadeh, Armin; Godoy, Gustavo; Miller, Julie M.; Lin, Shezhang; Vavere, Andrea; Paul, Narinder; Niinuma, Hiroyuki; Hoe, John; Brinker, Jeffrey; Khosa, Faisal; Sarwar, Sheryar; Lima, Joao; Clouse, Melvin E.

2012-01-01

OBJECTIVE Evaluations of stents by MDCT from studies performed at single centers have yielded variable results with a high proportion of unassessable stents. The purpose of this study was to evaluate the accuracy of 64-MDCT angiography (MDCTA) in identifying in-stent restenosis in a multicenter trial. MATERIALS AND METHODS The Coronary Evaluation Using Multidetector Spiral Computed Tomography Angiography Using 64 Detectors (CORE-64) Multicenter Trial and Registry evaluated the accuracy of 64-MDCTA in assessing 405 patients referred for coronary angiography. A total of 75 stents in 52 patients were assessed: 48 of 75 stents (64%) in 36 of 52 patients (69%) could be evaluated. The prevalence of in-stent restenosis by quantitative coronary angiography (QCA) in this subgroup was 23% (17/75). Eighty percent of the stents were ≤ 3.0 mm in diameter. RESULTS The overall sensitivity, specificity, positive predictive value, and negative predictive value to detect 50% in-stent stenosis visually using MDCT compared with QCA was 33.3%, 91.7%, 57.1%, and 80.5%, respectively, with an overall accuracy of 77.1% for the 48 assessable stents. The ability to evaluate stents on MDCTA varied by stent type: Thick-strut stents such as Bx Velocity were assessable in 50% of the cases; Cypher, 62.5% of the cases; and thinner-strut stents such as Taxus, 75% of the cases. We performed quantitative assessment of in-stent contrast attenuation in Hounsfield units and correlated that value with the quantitative percentage of stenosis by QCA. The correlation coefficient between the average attenuation decrease and ≥ 50% stenosis by QCA was 0.25 (p = 0.073). Quantitative assessment failed to improve the accuracy of MDCT over qualitative assessment. CONCLUSION The results of our study showed that 64-MDCT has poor ability to detect in-stent restenosis in small-diameter stents. Evaluability and negative predictive value were better in large-diameter stents. Thus, 64-MDCT may be appropriate for stent assessment in only selected patients. PMID:20028909

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 within the bile duct is rare but possible, and it is important to determine the risk factors involved in stent migration. PMID:24574806

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 its deliverability in patients with stable coronary disease.

Primary Report of Totally Tubeless Percutaneous Nephrolithotomy Despite Pelvi-calyceal Perforations.

PubMed

Aghamir, Seyed Mohammad Kazem; Salavati, Alborz; Hamidi, Morteza; FallahNejad, Asghar

2017-07-02

Nephrostomy tube insertion and/or a ureteral stent placement is advised when pelvi-calyceal perforations are encountered during percutaneous nephrolithotomy (PNL) nevertheless totally tubeless PNL is a possible exit strategy in percutaneous renal surgery therefore case series on the short term clinical outcomes of noninvasive management of iatrogenic pelvicalyceal perforations encountered during PNL is presented. During retrospective analysis of 1271 PNL procedures, 25 incidents of accidental ureteral catheter/ jj stent dislodgement during first 24 post-operative hours were identified in patient who had pelvi calyceal perforations and had no nephrostomy tube (tubeless). Thirteen patients could not be re-stented nor a nephrostomytube could have been placed for them mainly due to patient refusal or comorbid conditions. The main outcome was rate of successful noninvasive management. Eighteen Patients bearing mucosal tears (grade I trauma) or visible peri-pelvic fat (grade II) successfully recovered without need for ureteral stenting or nephrostomy (72.0%). In seven (28.0%) cases of extension of the perforation into the peri-pelvic fat (grade III), either nephrostomy insertion or JJ stenting was needed for resolution of fever and urinoma. The major limitation was the necessity to exclude patients and manage them in the standard fashion according to clinical guidelines. Iatrogenic perforations of the collecting system are quite diverse in terms of severity that result in different natural histories and not all might need urinary diversion via nephrostomy or ureteral stenting.Low grade perforations may be successfully managed in totally tubeless fashion nevertheless further prospective investigations seem warranted.

Evaluation of the Biodurability of Polyurethane-Covered Stent Using a Flow Phantom

PubMed Central

Kim, Dong Hyun; Choi, Jung Ryul; Byun, Ju Nam; Kim, Young Chul; Ahn, Young Moo

2001-01-01

Objective To evaluate the biodurability of the covering material in retrievable metallic stents covered with polycarbonate polyurethane. Materials and Methods Using a peristaltic pump at a constant rate of 1ml/min, bile was recirculated from a reservoir through a long tube containing four stents. Each of these was removed from the system every two weeks and a radial tensile strength test and scanning electron microscopy (SEM) were performed. Each stent, removed at 2, 4, 6 and 8 weeks, was compared with a control stent not exposed to bile juice. Results Gross examination showed that stents were intact at 2 weeks, but at 4, 6 and 8 weeks cracks were observed. The size of these increased gradually in accordance with the duration of exposure, and at 8 weeks several large holes in the polyurethane membrane were evident. With regard to radial tensile strength, extension and peak load at break were 84.47% and 10.030 N/mm, 54.90% and 6.769 N/mm, 16.55% and 2.452 N/mm, 11.21% and 1.373 N/mm at 0, 2, 4 and 6 weeks, respectively. Scanning electron microscopy at 2 weeks revealed intermittent pitting and cracking, and examination at 4, 6 and 8 weeks showed that the size of these defects was gradually increasing. Conclusion When the polyurethane membrane was exposed to bile, biodegradation was first observed at week two and increased gradually according to the duration of exposure. PMID:11752974

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.

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.

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

Krokidis, Miltiadis, E-mail: mkrokidis@hotmail.com; Fanelli, Fabrizio; Orgera, Gianluigi

The purpose of this study was to compare the clinical effectiveness of expanded polytetrafluoroethylene/fluorinated-ethylene-propylene (ePTFE/FEP)-covered stents with that of uncovered nitinol stents for the palliation of malignant jaundice caused by inoperable pancreatic head cancer. Eighty patients were enrolled in a prospective randomized study. Bare nitinol stents were used in half of the patients, and ePTFE/FEP-covered stents were used in the remaining patients. Patency, survival, complications, and mean cost were calculated in both groups. Mean patency was 166.0 {+-} 13.11 days for the bare-stent group and 234.0 {+-} 20.87 days for the covered-stent group (p = 0.007). Primary patency rates atmore » 3, 6, and 12 months were 77.5, 69.8, and 69.8% for the bare-stent group and 97.5, 92.2, and 87.6% for the covered-stent group, respectively. Mean secondary patency was 123.7 {+-} 22.5 days for the bare-stent group and 130.3 {+-} 21.4 days for the covered-stent group. Tumour ingrowth occurred exclusively in the bare-stent group in 27.5% of cases (p = 0.002). Median survival was 203.2 {+-} 11.8 days for the bare-stent group and 247.0 {+-} 20 days for the covered-stent group (p = 0.06). Complications and mean cost were similar in both groups. Regarding primary patency and ingrowth rate, ePTFE/FEP-covered stents have shown to be significantly superior to bare nitinol stents for the palliation of malignant jaundice caused by inoperable pancreatic head cancer and pose comparable cost and complications. Use of a covered stent does not significantly influence overall survival rate; nevertheless, the covered endoprosthesis seems to offer result in fewer reinterventions and better quality of patient life.« less

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.

Study design and rationale of the 'Balloon-Expandable Cobalt Chromium SCUBA Stent versus Self-Expandable COMPLETE-SE Nitinol Stent for the Atherosclerotic ILIAC Arterial Disease (SENS-ILIAC Trial) Trial': study protocol for a randomized controlled trial.

PubMed

Choi, Woong Gil; Rha, Seung Woon; Choi, Cheol Ung; Kim, Eung Ju; Oh, Dong Joo; Cho, Yoon Hyung; Park, Sang Ho; Lee, Seung Jin; Hur, Ae Yong; Ko, Young Guk; Park, Sang Min; Kim, Ki Chang; Kim, Joo Han; Kim, Min Woong; Kim, Sang Min; Bae, Jang Ho; Bong, Jung Min; Kang, Won Yu; Seo, Jae Bin; Jung, Woo Yong; Cho, Jang Hyun; Kim, Do Hoi; Ahn, Ji Hoon; Kim, Soo Hyun; Jang, Ji Yong

2016-06-25

The self-expandable COMPLETE™ stent (Medtronic) has greater elasticity, allowing it to regain its shape after the compression force reduces, and has higher trackability, thus is easier to maneuver through tortuous vessels, whereas the balloon-expandable SCUBA™ stent (Medtronic) has higher radial stiffness and can afford more accurate placement without geographic miss, which is important in aortoiliac bifurcation lesions. To date, there have been no randomized control trials comparing efficacy and safety between the self-expanding stent and balloon-expandable stent in advanced atherosclerotic iliac artery disease. The purpose of our study is to examine primary patency (efficacy) and incidence of stent fracture and geographic miss (safety) between two different major representative stents, the self-expanding nitinol stent (COMPLETE-SE™) and the balloon-expanding cobalt-chromium stent (SCUBA™), in stenotic or occlusive iliac arterial lesions. This trial is designed as a prospective, randomized, multicenter trial to demonstrate a noninferiority of SCUBA™ stent to COMPLETE-SE™ stent following balloon angioplasty in iliac arterial lesions, and a total of 280 patients will be enrolled. The primary end point of this study is the rate of primary patency in the treated segment at 12 months after intervention as determined by catheter angiography, computed tomography angiography, or duplex ultrasound. The SENS-ILIAC trial will give powerful insight into whether the stent choice according to deployment mechanics would impact stent patency, geographic miss, or stent fracture in patients undergoing stent implantation in iliac artery lesions. National Institutes of Health Clinical Trials Registry (ClinicalTrials.gov identifier: NCT01834495 ), registration date: May 8, 2012.

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.

Stent deployment protocol for optimized real-time visualization during endovascular neurosurgery.

PubMed

Silva, Michael A; See, Alfred P; Dasenbrock, Hormuzdiyar H; Ashour, Ramsey; Khandelwal, Priyank; Patel, Nirav J; Frerichs, Kai U; Aziz-Sultan, Mohammad A

2017-05-01

Successful application of endovascular neurosurgery depends on high-quality imaging to define the pathology and the devices as they are being deployed. This is especially challenging in the treatment of complex cases, particularly in proximity to the skull base or in patients who have undergone prior endovascular treatment. The authors sought to optimize real-time image guidance using a simple algorithm that can be applied to any existing fluoroscopy system. Exposure management (exposure level, pulse management) and image post-processing parameters (edge enhancement) were modified from traditional fluoroscopy to improve visualization of device position and material density during deployment. Examples include the deployment of coils in small aneurysms, coils in giant aneurysms, the Pipeline embolization device (PED), the Woven EndoBridge (WEB) device, and carotid artery stents. The authors report on the development of the protocol and their experience using representative cases. The stent deployment protocol is an image capture and post-processing algorithm that can be applied to existing fluoroscopy systems to improve real-time visualization of device deployment without hardware modifications. Improved image guidance facilitates aneurysm coil packing and proper positioning and deployment of carotid artery stents, flow diverters, and the WEB device, especially in the context of complex anatomy and an obscured field of view.

[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.

Coagulation and complement activation.

PubMed

Christensen, K; Larsson, R; Emanuelsson, H; Elgue, G; Larsson, A

2001-02-01

The purpose of this investigation was to assess the effect of heparin coating of a new stent construction (Stent Graft, Jomed Implantate GmbH, Germany) on platelet and coagulation activity. Stent grafts with an ePTFE membrane interfoliated between two stents were deployed in tubings to form Chandler loops. Fresh human blood with a low concentration of heparin was rotated for 1 h, then collected and used for measurements of platelet number, thrombin-antithrombin complex (TAT), CD11b, C3a and C5b-9. There were five study groups: Group 1, conventional unmodified stents (n = 8); Group 2, untreated stent grafts (n = 8); Group 3, heparin-coated stents and untreated membrane (n = 7); Group 4, heparin-coated stents and membrane (n = 8); Group 5, heparin-coated PVC tubings with no stents (n = 8). There was a significant drop in platelet count, increase in TAT-values and CD11b expression in Groups 1-3 but not in Group 4 compared to Group 5. Examination by scanning electron microscopy revealed extensive activation on non-modified stents but almost no deposition of thrombotic material on heparin-modified stent grafts. With unmodified stents and membrane there were signs of significant activation of platelets and coagulation. In contrast, the heparin-coated stent graft induced much less alterations, indicating improved blood compatibility.

A cost analysis of stenting in uncomplicated semirigid ureteroscopic stone removal.

PubMed

Seklehner, Stephan; Sievert, Karl-Dietrich; Lee, Richard; Engelhardt, Paul F; Riedl, Claus; Kunit, Thomas

2017-05-01

To evaluate the outcome and the costs of stenting in uncomplicated semirigid ureteroscopic stone removal. A decision tree model was created to evaluate the economic impact of routine stenting versus non-stenting strategies in uncomplicated ureteroscopy (URS). Probabilities of complications were extracted from twelve randomized controlled trials. Stone removal costs, costs for complication management, and total costs were calculated using Treeage Pro (TreeAge Pro Healthcare version 2015, Software, Inc, Williamstown Massachusetts, USA). Stone removal costs were higher in stented URS (€1512.25 vs. €1681.21, respectively). Complication management costs were higher in non-stented procedures. Both for complications treated conservatively (€189.43 vs. €109.67) and surgically (€49.26 vs. €24.83). When stone removal costs, costs for stent removal, and costs for complication management were considered, uncomplicated URS with stent placement yielded an overall cost per patient of €1889.15 compared to €1750.94 without stent placement. The incremental costs of stented URS were €138.25 per procedure. Semirigid URS with stent placement leads to higher direct procedural costs. Costs for managing URS-related complications are higher in non-stented procedures. Overall, a standard strategy of deferring routine stenting uncomplicated ureteroscopic stone removal is more cost efficient.

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

Malignant esophageal-tracheobronchial strictures: parallel placement of covered retrievable expandable nitinol stents.

PubMed

Nam, D H; Shin, J H; Song, H Y; Jung, G S; Han, Y M

2006-02-01

To assess the safety and clinical effectiveness of the parallel placement of covered retrievable expandable metallic stents in the palliative treatment of malignant esophageal and tracheobronchial strictures. Under fluoroscopic guidance, parallel stents were placed in 12 symptomatic patients with both malignant esophageal and tracheobronchial strictures. Seven of these 12 patients also had an esophagorespiratory fistula (ERF) and one patient had an esophagocutaneous fistula. Technical success, clinical improvement, complications, and survival rates were evaluated. A total of 28 esophageal and airway stents were successfully placed. The grade of dysphagia and dyspnea score significantly decreased after stent placement (P=0.002 and 0.003, respectively). ERF and esophagocutaneous fistula were sealed off in all eight patients after esophageal stent placement; however, the esophagocutaneous fistula reopened 1 month later. Complications included stent migration or expectoration (n=3), tracheal compression by the esophageal stent (n=3), new fistula development due to covering membrane degradation of the esophageal stent (n=1), and symptomatic sputum retention (n=1). Stent removal was easily performed for two stents; one migrated stent and the other with covering membrane degradation. All 12 patients died within the mean survival period of 72.50 days (range 7-375 days). Parallel placement of covered retrievable expandable metallic stents is safe and effective for the palliative treatment of malignant esophageal and tracheobronchial strictures.

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.

Natural stent in the management of post-intubation tracheal stenosis.

PubMed

Park, Hye Yun; Kim, Hojoong; Koh, Won-Jung; Suh, Gee Young; Chung, Man Pyo; Kwon, O Jung

2009-05-01

The treatment choice for post-intubation tracheal stenosis (PITS) in patients for whom surgery is not initially feasible is bronchoscopic silicone stenting. A new silicone stent, called the Natural stent (N stent), was investigated for its clinical efficacy and safety in patients with PITS. A retrospective review was conducted of 32 patients with PITS who underwent N stenting between November 2001 and December 2006 and were followed for at least 12 months. Airway dilatation with combined modalities such as Nd:YAG laser, ballooning or bougienage was followed by N stent insertion. After intervention, all patients had symptomatic and spirometric improvement without immediate complications. Removal of the stent without re-stenosis was successful in 38% of the patients at a median time of 7 months after insertion. The stent could not be removed or needed reinsertion in 31% of patients, and 16% of patients underwent surgery after initial stabilization by stenting. Late complications were stent migration (34%), mucostasis (31%), granulation tissue formation (38%) and re-stenosis (40%). All patients tolerated the management of complications during a median follow up of 22 months. Bronchoscopic N stenting is an effective treatment for patients with PITS in whom surgery is not feasible on initial presentation. Further stent development is necessary to reduce the late complication rate.

A Bumpy and Winding but Right Path to Domestic Drug-Eluting Coronary Stents

PubMed Central

Cho, Jae Yeong; Ahn, Youngkeun

2013-01-01

Restenosis and stent thrombosis remain major concerns after percutaneous coronary intervention for the treatment of coronary artery disease. The present review was undertaken in order to highlight the various coronary stents that have been investigated in our Heart Research Center, and how far we have come from the first heparin-coated stent first used in the late 1990s. Thereafter, from the abciximab-coated stent to the current gene-delivery stent and other newer agents, our group has applied a range of techniques in this field. However, in groups similar to ours, the restenosis rates of such stents are still high for second-generation drug-eluting stents (DESs). Moreover, our nation imports almost all of these types of stents from other countries. Thus, we need to develop domestic coronary stents. Research into newer DESs are warranted in Korea so as to achieve improved safety and efficacy outcomes. PMID:24255648

Drug-eluting stents to prevent stent thrombosis and restenosis.

PubMed

Im, Eui; Hong, Myeong-Ki

2016-01-01

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

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.

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

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.

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.