Balloon-expandable Coronary Stent Research Articles

Use of drug-eluting, balloon-expandable resolute onyx coronary stent as a novel treatment strategy for vertebral artery ostial stenosis: Case series.

Vertebral artery (VA) ostial stenosis is notoriously difficult to treat using bare-metal stents owing to high rates of restenosis and stent kinking and breakage. We investigated the safety and effectiveness of treatment with a drug-eluting, balloon-expandable coronary stent (Resolute Onyx, Medtronic). Our prospectively maintained database was retrospectively searched for consecutive patients diagnosed with VA ostial stenosis who underwent Resolute Onyx stenting with/without angioplasty between January 1, 2015 and January 1, 2022. Patient demographics and clinical and radiographic presentations were recorded. Occlusion location, stenosis severity, contralateral disease, devices used, and intraprocedural and postprocedural complications were noted. Outcomes were assessed based on new or recurrent stroke, transient ischemic attack (TIA), or intracranial hemorrhage (ICH). Patients were followed up clinically and with radiographic imaging for in-stent stenosis. Twenty-six patients were included in our study (21 men [80.8%]; mean age 70.3 ± 9.8 years). Symptomatic patients presented with TIA (11/26, 42.3%) and stroke (10/26; 38.5%). Mean stenosis in the study cohort was 74.9 ± 13.0%. One (3.8%) intraprocedural complication was encountered whereby the stent failed to open despite several attempts and was exchanged with a new one without issues. No in-hospital postprocedure stroke, TIA, or mortality was reported. During a mean 16.2 ± 13.6 months' follow up, two patients developed symptomatic in-stent restenosis that was treated with balloon angioplasty. We report the first case series of Resolute Onyx drug-eluting stenting including 30-day postprocedure stroke/TIA rates and clinical/radiographic follow up and demonstrate safe and effective treatment of symptomatic and asymptomatic VA ostial stenosis.

Correction to: Balloon expandable coronary stent materials: a systematic review focused on clinical success

Correction to: Balloon expandable coronary stent materials: a systematic review focused on clinical success

Balloon expandable coronary stent materials: a systematic review focused on clinical success

Balloon expandable coronary stenting has revolutionized the field of interventional cardiology as a potential, minimally invasive modality for treating coronary artery disease. Even though stenting is successful compared to angioplasty (that leaves no stent in place), still there are many associated clinical complications. Bare metal stents are associated with in-stent restenosis caused mostly by neointimal hyperplasia, whereas success of drug-eluting stents comes at the expense of late-stent thrombosis and neoatherosclerosis. Even though innovative and promising, clinical trials with bioabsorbable stents reported thrombosis and a rapid pace of degradation without performing scaffolding action in several instances. It should be noted that a vast majority of these stents are based on a metallic platform which still holds the potential to mitigate major cardiovascular events and reduced economic burden to patients, alongside continuous improvement in stent technology and antiplatelet regimes. Hence, a systematic review was conducted following PRISMA guidelines to assess the clinically relevant material properties for a metallic stent material. From a materials perspective, the major causes identified for clinical failure of stents are inferior mechanical properties and blood-material interaction–related complications at the stent surface. In addition to these, the stent material should possess increased radiopacity for improved visibility and lower magnetic susceptibility values for artefact reduction. Moreover, the review provides an overview of future scope of percutaneous coronary interventional strategy. Most importantly, this review highlights the need for an interdisciplinary approach by clinicians, biomaterial scientists, and interventional cardiologists to collaborate in mitigating the impediments associated with cardiovascular stents for alleviating sufferings of millions of people worldwide.

Carotid Artery Stenting Using Balloon-Expandable Coronary Stent: Intentional Use for Staged Angioplasty.

We report carotid artery stenting (CAS) using balloon-expandable coronary (BECo) stent. The materials in this study consist of 15 cases of high-grade stenosis in internal carotid artery (ICA) in which self-expanding carotid (SECa) stent was not utilized. There were two groups why BECo stent was used instead of SECa stent: alternative group and intentional group. The alternative group was subdivided into two groups: access difficulty of guiding catheter and access difficulty of SECa stent. The alternative group included 11 cases (access difficulty of guiding catheter in 10 and access difficulty of SECa stent in 1), and the intentional group included 4 cases. There were four cases using transbrachial approach. All the intentional group cases were the first stage of staged angioplasty (SAP). The second stage of SAP was PTA in two and SECa stent over the BECo stent in two. There was no complication related to CAS. CAS using BECo stent is one of the choices for the first stage of SAP, if stent placement instead of PTA is required at the first stage. It is also the useful alternative for the patient having difficulty of SECa stent.

Future Balloon-Expandable Stents: High or Low-Strength Materials?

Recent progress in material science allows researchers to use novel materials with enhanced capabilities like optimum biodegradability, higher strength, and flexibility in the design of coronary stents. Considering the wide range of mechanical properties of existing and newfangled materials, finding the influence of variations in mechanical properties of stent materials is critical for developing a practical design. The sensitivity of stent functional characteristics to variations in its material plastic properties is obtained through FEM modeling. Balloon-expandable coronary stent designs: Absorb BVS, and Xience are examined for artificial and commercial polymeric, and metallic materials, respectively. Standard tests including (1) the crimping process followed by stent implantation in an atherosclerotic artery and (2) the three-point bending test, have been simulated according to ASTM standards. In Absorb BVS, materials with higher yield stress than PLLA have similar residual deflection and maximum bending force to PLLA, which is not the case for Xience stent and Co-Cr. Moreover, elevated yield stress significantly reduces stent flexibility only in Xience stent. For both stents, with different degree of influence, an increase in yield or ultimate stress improves stent radial strength and stiffness and reduces arterial stress and plastic strain of stent, which consequently enhances the stent mechanical performance. Contrarily, yield or ultimate stress elevation increases stent recoil which adversely affects stent performance. Using high-strength materials has a double-edged sword effect on the stent performance and existing uncertainty in the precise estimate of stent mechanical properties adversely affects the reliability of numerical models' predictions.

Application of finite element analysis on balloon expandable coronary stents: A review

Numerical analysis of complex physical environment continues to be preferred over “build and test” approach in product development process. Finite Element Analysis (FEA) of coronary artery stenting is studied and researched worldwide for many years. Potential of using FEA for mimicking in-vivo is high as experimental test is ruled out for variety of reasons. This review aims at discussing issues and challenges of numerical simulation based on part of available literature on usage of FEA techniques for investigating behavior of balloon expandable (BE) coronary stents inside artery. Literatures of past 16 years of study on the structural analysis is summarized and potential issues for research is discussed. Study tries to investigate deployment characteristics and biomechanical response of artery post stenting and significance of non-physiological conditions induced. Effects of geometrical parameters, simulation strategies are summarized. Study mainly underscores the potential challenges of reliable numerical investigation. Scope of FEA in predicting contributor for in-stent restenosis (ISR), a major drawback of stenting procedure, by correlating the engineering aspect of stent design and its clinical significance supported by clinical trials are highlighted. Study is expected to serve as qualitative assessment for cardiologists to minimize procedural failure and quantitative tool for the designers for stent optimization.

Numerical investigation of influence of number of stent cells and type of link on expansion and haemodynamic behaviour of balloon-expandable coronary stent

Coronary stents are tubular, mesh-like structures used to force open clogged artery. Mounted on an inflatable balloon, stent compresses calcified plaque inside atherosclerotic artery with an inflating device, which transfers the load through the compliant balloon, thus maintaining the patency of lumen. One of the contributors for success of angioplasty is type of stents, which mainly differs in its geometrical design. A clinician recommends a stent based on comparative advantages. An ideal stent should be flexible to manoeuver through tortuous artery, easy to expand, provide good scaffolding to the vessel, have less radial recoil and foreshortening, possess uniformity in expansion and induce minimum alteration in physiological blood flow dynamics. In a stent these parameters are in competition with each other and are optimized by trade-offs. The present work tries to sequentially investigate the effect of number of stent cells and type of links on the expansion and haemodynamics behaviour through computational analysis based on finite element and finite volume techniques. The study compares performance within same classes of designs rather than comparing the designs that are completely different form each other. Results show that more number of stent cells in longitudinal direction considerably decrease the radial recoil, but increase the foreshortening effect. Restenosis-prone zones are localized around the stent struts and are predominant during end of systolic phase of cardiac cycle. Shorter links are preferred for better recoil and favourable distribution of wall shear stress while longer links are preferred for favourable foreshortening.

Abstract WP118: Incidence and Management of Re-stenosis in Patients Stented for Intracranial Atherosclerotic Disease: A Consecutive Series of 226 Patients

Introduction: Angioplasty and stenting for intracranial atherosclerotic disease can re-establish adequate luminal diameter in highly stenotic arteries and improve cerebral blood flow. As in other vascular territories, intracranial stented arteries may develop delayed re-stenosis due to progression of atherosclerotic disease or endothelial hyperplasia. The primary strategies for management of re-stenosis have included aggressive medical therapy, angioplasty only, and repeat angioplasty and stenting. Materials and Methods: A total of 226 patients underwent intracranial angioplasty and stenting for symptomatic ICAD from 2000-2017. Patients were treated with balloon expandable coronary stents until 2002, when self-expanding intracranial nitinol stents became available. The series included: 21 balloon expandable coronary stents, 33 Neuroform stents, 37 Enterprise stents, and 135 Wingspan stents. Of this group, 210 patients had delayed follow up intracranial vascular imaging at 6 months, 1 year, and longer. In follow up, 24 of the 210 patients (11.4 %) developed significant re-stenosis, defined as 70% or greater. Eleven of the patients were symptomatic and 13 had no symptoms. A total of 17 patients underwent endovascular treatment of their re-stenosis, and 7 had medical management only. Results: The mean time interval for re-stenosis was 8.7 months. Of the 17 patients treated with endovascular therapy for re-stenosis, 4 patients had angioplasty only and 13 patients had angioplasty and stenting. There was one peri-procedural stroke in this group (5.9%) and no other strokes in the follow up period (mean 2.4 years, range 6 months - 7 years). Of the 7 patients who were managed medically, 1 patient had a stroke (14.3%) in the follow up period at 10 months (mean follow up 2.1 years, range 3 months - 5 years). Discussion: The preliminary data from this study suggests that patients with severe re-stenosis may be at significant risk of stroke, even if the re-stenosis is currently asymptomatic. As with other vascular territories, re-stenosis can be managed with multiple modalities, but repeat angioplasty and stenting in this series appears to be a low risk and viable option for these patients compared with medical therapy alone.

Numerical analysis of crimping and inflation process of balloon-expandable coronary stent using implicit solution.

The paper presents an applied methodology for numerical finite element analysis of coronary stent crimping and the free inflation process with the use of a folded noncompliant angioplasty balloon. The use of an implicit scheme is considered as the most original part of the work, as an explicit finite element procedure is very often preferred. Hitherto, when the implicit solution was used for the finite element solution, the simulated issue was largely simplified. Therefore, the authors focused on the modelling methodology with minimum possible simplification, ie, a full load path (compression and inflation in single analysis), solid element discretization, and sophisticated contact models (bodies with highly different stiffness). The obtained results are partially compared with experimental data (radial force during the crimping procedure) and present satisfactory compliance. The authors believe that presented methodology allow for significant improvement of the obtained results, as well as potential extension of the research scope, compared to previous efforts performed using the explicit integration scheme. Moreover, the presented methodology is believed to be suitable for sensitivity and optimization studies.

Design and modeling balloon-expandable coronary stent for manufacturability

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

Percutaneous transluminal angioplasty and stenting for severe stenosis of the intracranial extradural internal carotid artery causing transient ischemic attack or minor stroke.

The purpose of this study is to assess the technical feasibility and clinical efficacy of percutaneous transluminal angioplasty and stenting (PTAS) for symptomatic stenosis of the intracranial extradural (petrous and cavernous) internal carotid artery (ICA).Review of medical records identified 26 consecutive patients who underwent PTAS using a balloon-expandable coronary stent (n = 15, 57.7%) or a Wingspan self-expandable stent (n = 11, 42.3%) for treatment of severe stenosis (>70%) involving the intracranial extradural ICA. The inclusion criteria were transient ischemic attack with an ABCD(2) score of ≥3 (n = 12, 46.2%) or minor stroke with an NIHSS score of ≤4 (n = 14, 53.8%). Technical success rates, complications, and angiographic and clinical outcomes were analyzed retrospectively.PTAS was technically successful in all patients. The mean stenosis ratio decreased from 77.1% to 10.0% immediately after PTAS. The overall incidence of procedural complications was 23.1%, and the postoperative permanent morbidity/mortality rate was 7.7%. A total of 22 patients were tracked over an average period of 29.9 months. During the observation period, 20 patients (90.9%) had no further cerebrovascular events and stroke recurrence occurred in two patients (9.1%), resulting in an annual stroke risk of 3.7%. Two cases (11.1%) of significant in-stent restenosis (>50%) were found on follow-up angiography (n = 18).PTAS for severe stenosis (>70%) involving the intracranial extradural ICA showed a good technical feasibility and favorable clinical outcome in patients with transient ischemic attack or minor stroke.

Sequential Structural and Fluid Dynamics Analysis of Balloon-Expandable Coronary Stents: A Multivariable Statistical Analysis.

Several clinical studies have identified a strong correlation between neointimal hyperplasia following coronary stent deployment and both stent-induced arterial injury and altered vessel hemodynamics. As such, the sequential structural and fluid dynamics analysis of balloon-expandable stent deployment should provide a comprehensive indication of stent performance. Despite this observation, very few numerical studies of balloon-expandable coronary stents have considered both the mechanical and hemodynamic impact of stent deployment. Furthermore, in the few studies that have considered both phenomena, only a small number of stents have been considered. In this study, a sequential structural and fluid dynamics analysis methodology was employed to compare both the mechanical and hemodynamic impact of six balloon-expandable coronary stents. To investigate the relationship between stent design and performance, several common stent design properties were then identified and the dependence between these properties and both the mechanical and hemodynamic variables of interest was evaluated using statistical measures of correlation. Following the completion of the numerical analyses, stent strut thickness was identified as the only common design property that demonstrated a strong dependence with either the mean equivalent stress predicted in the artery wall or the mean relative residence time predicted on the luminal surface of the artery. These results corroborate the findings of the large-scale ISAR-STEREO clinical studies and highlight the crucial role of strut thickness in coronary stent design. The sequential structural and fluid dynamics analysis methodology and the multivariable statistical treatment of the results described in this study should prove useful in the design of future balloon-expandable coronary stents.

An experimental-nonlinear finite element study of a balloon expandable stent inside a realistic stenotic human coronary artery to investigate plaque and arterial wall injury.

The stresses induced within plaque tissues and arterial layers during stent expansion inside an atherosclerotic artery can be exceeded from the yield stresses of those tissues and, consequently, lead to plaque or arterial wall rupture. The distribution and magnitude of the stresses in the plaque-artery-stent structure might be distinctly different for different plaque types. In this study, the mechanical properties of six healthy and atherosclerotic human coronary arteries were determined for application in plaque and arterial vulnerability assessment. A nonlinear finite element simulation based on an Ogden material model was established to investigate the effect of plaque types on the stresses induced in the arterial wall during implantation of a balloon expandable coronary stent. The atherosclerotic artery was assumed to consist of a plaque and normal arterial tissues on its outer side. The results indicated a significant influence of plaque types on the maximum stresses induced within the plaque wall and arterial wall during stenting but not when computing maximum stress on the stent. The stress on the stiffest calcified plaque wall was 3.161 MPa, whereas cellular and hypocellular plaques showed relatively less stress on their wall. The highest von Mises stresses within the arterial wall were observed on the hypocellular plaque, whereas the lowest stresses were seen to be located in the calcified and cellular plaques. Although the computed stresses on the arterial wall for the calcified and cellular plaques were not high enough to invoke a rupture, the stress on the hypocellular plaque was relatively higher than that of the strength of the arterial wall. These findings may have implications not only for understanding the stresses induced in plaque and the arterial wall, but also for developing surgeries such as balloon-angioplasty and stenting.

TCT-447 Usefulness of Polyzene-F nanocoated stent to facilitate reendothelialization and reduce thrombus formation. In vivo results of stented rabbit iliac arteries

The CeloNova COBRA PzF™ Coronary Stent is a new stent design, balloon expandable cobalt chromium alloy coronary stent that is pre-mounted on a custom rapid exchange balloon delivery catheter. The alloy stent is surface treated with a nano-layer Polyzene®-F (PzF). Polyzene-F is an inorganic

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

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

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

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

A nonlinear finite element simulation of balloon expandable stent for assessment of plaque vulnerability inside a stenotic artery.

The stresses induced on plaque wall during stent implantation inside a stenotic artery are associated with plaque rupture. The stresses in the plaque-artery-stent structure appear to be distinctly different for different plaque types in terms of both distribution and magnitude. In this study, a nonlinear finite element simulation was executed to analyze the influence of plaque composition (calcified, cellular, and hypocellular) on plaque, artery layers (intima, media, and adventitia), and stent stresses during implantation of a balloon expandable coronary stent into a stenosed artery. The atherosclerotic artery was assumed to consist of a plaque and normal arterial tissues on its outer side. The results revealed a significant influence of plaque types on the maximum stresses induced within plaque wall and artery layers during stenting, but not when calculating maximum stress on stent. The stress on stiffer calcified plaque wall was in the fracture level (2.21 MPa), whereas cellular and hypocellular plaques play a protective role by displaying less stress on their wall. The highest von Mises stresses were observed on less stiff media layer. The findings of this study suggest a lower risk of arterial vascular injury for calcified plaque, while higher risk of plaque ruptures for cellular and hypocellular plaques.

Design optimization of balloon-expandable coronary stent

To prevent the dogboning effect of stent implantation (i.e. the ends of a stent opening first during expansion), an adaptive optimization method based on the kriging surrogate model is proposed to ...

Sole Stenting Technique for the Treatment of Uncoilable Very Small Aneurysms in the Intracranial Internal Carotid Artery

The treatment of very small aneurysms with diameter of less than 3 mm remains a challenge for both endovascular and surgical treatment. Endovascular treatment of these lesions may be difficult and is associated with a high risk of complications because of their small size. The present study evaluated the safety, feasibility, and efficacy of the endovascular treatment using sole stenting technique for uncoilable very small aneurysms of the intracranial internal carotid artery (ICA). From August 2004 through January 2010, eight very small aneurysms of intracranial ICA in eight patients were treated with endovascular sole stenting technique. All very small aneurysms were ruptured (n = 3) or aneurysms associated with another ruptured (n = 2) and unruptured aneurysms (n = 3) in the same artery. Stents were Neuroform and balloon expandable coronary stents. Stent deployment was carried out without difficulty in all patients. Single stent deployment was done for six aneurysms, and double stents in two aneurysms. The immediate angiographic results were partial occlusion in one case and no occlusion in seven cases. One direct carotid-cavernous fistula occurred during coronary stenting without permanent neurological deficit. No neurological deterioration or hemorrhagic complication was seen during the follow-up period in seven patients. Follow-up angiography (mean 9 months) was available in six patients and revealed complete occlusion in four and no occlusion in two cases. Sole stenting technique may be a feasible and effective therapeutic alternative for uncoilable very small aneurysms. The long-term efficacy and durability of stenting for these lesions remains to be determined in a large series.

Stenting in acute stroke: point

The introduction of permanent and then temporary stenting over the past decade has advanced our ability to revascularize occluded intracranial vessels efficiently in the setting of acute ischemic stroke. The...