Coronary Stent Research Papers - Academia.edu (original) (raw)

Stent thrombosis (ST) is a frequently reported complication in cardiac patients with percutaneous coronary intervention (PCI) that adversely impacts their prognostic outcomes. Medical literature reveals several baseline characteristics of... more

Stent thrombosis (ST) is a frequently reported complication in cardiac patients with percutaneous coronary intervention (PCI) that adversely impacts their prognostic outcomes. Medical literature reveals several baseline characteristics of PCI patients that may predict their predisposition to ST and its potential complications. Our systematic review and meta-analysis aimed to determine the diagnostic significance of these baseline parameters in terms of determining the risk of ST among adult patients with PCI.

A stent is a medical device designed to serve as a temporary or permanent internal scaffold to maintain or increase the lumen of a body conduit. The researchers and engineers diverted to investigate biodegradable materials due to the... more

A stent is a medical device designed to serve as a temporary or permanent internal scaffold to maintain or increase the lumen of a body conduit. The researchers and engineers diverted to investigate biodegradable materials due to the limitation of metallic materials in stent application such as stent restenosis which requires prolonged anti platelet therapy, often result in smaller lumen after implantation and obstruct re-stenting treatments. Biomedical implants with temporary function for the vascular intervention are extensively studied in recent years. The rationale for biodegradable stent is to provide the support for the vessel in predicted period of time and then degrading into biocompatible constituent. The degradation of stent makes the re-stenting possible after several months and also ameliorates the vessel wall quality. The present article focuses on the biodegradable materials for the cardiovascular stent. The objective of this review is to describe the possible biodegradable materials for stent and their properties such as design criteria, degradation behavior, drawbacks and advantages with their recent clinical and preclinical trials.

Still scientists are searching cause of Covid19, because no trace found of Human, Animal and Lab Virus. But similarity with Bats, Penguins and Vending Machine Frozen Food issue is existed. #COVID19 #Pandemic #DeltaVirus #Corona #WuhanLab... more

Still scientists are searching cause of Covid19, because no trace found of Human, Animal and Lab Virus. But similarity with Bats, Penguins and Vending Machine Frozen Food issue is existed.
#COVID19 #Pandemic #DeltaVirus #Corona #WuhanLab
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Background: Drug-eluting stents (DES) have dramatically reduced restenosis rates compared to bare metal stents and are widely used in coronary artery angioplasty. The anti-proliferative nature of the drugs reduces smooth muscle cell (SMC)... more

Background: Drug-eluting stents (DES) have dramatically reduced restenosis rates compared to bare metal stents and are widely used in coronary artery angioplasty. The anti-proliferative nature of the drugs reduces smooth muscle cell (SMC) proliferation effectively, but unfortunately also negatively affects endothelialization of stent struts, necessitating prolonged dual anti-platelet therapy. Cell-type specific therapy may prevent this complication, giving rise to safer stents that do not require additional medication. 6-Mercaptopurine (6-MP) is a drug with demonstrated cell-type specific effects on vascular cells both in vitro and in vivo, inhibiting proliferation of SMCs while promoting survival of endothelial cells. In rabbits, we demonstrated that DES locally releasing 6-MP during 4 weeks reduced in-stent stenosis by inhibiting SMC proliferation and reducing inflammation, without negatively affecting endothelialization of the stent surface. The aim of the present study was to investigate whether 6-MP-eluting stents are similarly effective in preventing stenosis in porcine coronary arteries after 3 months, in order to assess the eligibility for human application. Methods: 6-MP-eluting and polymer-only control stents (both n = 7) were implanted in porcine coronary arteries after local balloon injury to assess the effect of 6-MP on vascular lesion formation. Three months after implantation, stented coronary arteries were harvested and analyzed. Results: Morphometric analyses revealed that stents were implanted reproducibly and with limited injury to the vessel wall. Unexpectedly, both in-stent stenosis (6-MP: 41.1 ± 10.3 %; control: 29.6 ± 5.9 %) and inflammation (6-MP: 2.14 ± 0. 51; control: 1.43 ± 0.45) were similar between the groups after 3 months. Conclusion: In conclusion, although 6-MP was previously found to potently inhibit SMC proliferation, reduce inflammation and promote endothelial cell survival, thereby effectively reducing in-stent restenosis in rabbits, stents containing 300 μg 6-MP did not reduce stenosis and inflammation in porcine coronary arteries.

The surface texture and chemistry of WE43 absorbable magnesium stents (AMS) and tube specimens processed by chemical and reactive ion etching (RIE) were investigated. Tube specimens were produced in three different conditions, namely as... more

The surface texture and chemistry of WE43 absorbable magnesium stents (AMS) and tube specimens processed by chemical and reactive ion etching (RIE) were investigated. Tube specimens were produced in three different conditions, namely as received, chemically etched and plasma etched. The results of scanning electron microscopy, atomic force microscopy and energy dispersive X-ray spectroscopy studies showed that plasma etching and cleaning reduced surface roughness by 10% compared to chemical etching alone, and completely removed surface deposits remaining from the chemical etch process. The same combination of chemical and plasma etching processes was employed to produce AMS. Expansion tests demonstrated uniform stent expansion characteristics and confirmed the viability of the device. The results of this study show that RIE is an effective surface modification technique for absorbable magnesium devices.

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 mag-nesium... more

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 mag-nesium 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 influ-ence in directing subsequent corrosion behaviour within the material. In addition, the deployment and scaffolding char-acteristics of the magnesium stent are elucidated and con-trasted 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 experi-mental performance of a current AMS design and material whilst demonstrating the critical influence of plastic strain on the corrosion performance and scaffolding ability of an AMS.

The purpose of this paper is to know what the ideal financial audit model for private sector assistance is for the Covid-19 pandemic outbreak that occurred from late 2019 to mid-2020 transparent, measurable and protected from abuse. To... more

The purpose of this paper is to know what the ideal financial audit model for private sector assistance is for the Covid-19 pandemic outbreak that occurred from late 2019 to mid-2020 transparent, measurable and protected from abuse. To produce an ideal quality audit model, the auditor must carry out his work in accordance with established audit standards. In writing this study using descriptive qualitative research methods, literature review methods from various scientific journals related to the audit.

Stents used for cardiovascular applications are composed of three main elements; a metal, polymer coating and the specific drug component. Nickel-based metals and polymer coatings currently used in the stent market have increased the... more

Stents used for cardiovascular applications are composed of three main elements; a metal, polymer coating and the specific drug component. Nickel-based metals and polymer coatings currently used in the stent market have increased the recurrence of in-stent restenosis and stent failure due to inflammation. In this study, a Ti-8Mn alloy was used to fabricate a nanostructured surface that can be used for drug eluting stents to overcome the hypersensitivity of metals that are currently used in stent making as well as introducing a new built-in nano-drug reservoir instead of polymer coatings. Two different systems were studied: titanium dioxide nanotubes (NTs) and Ti-8Mn oxides NTs. The materials were characterized using field emission electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), roughness, wettability and surface energy measurements. Nanoindentation was used to evaluate the mechanical properties of the nanotubes as well as their stability. In-vitro cytotoxicity and cell proliferation assays were used to study the effect of the nanotubes on cell viability. Computational insights were also used to test the blood compatibility using band gap model analysis, comparing the band gap of the materials under investigation with that of the fibrinogen, in order to study the possibility of charge transfer that affects the blood clotting mechanism. In addition, the drug loading capacity of the materials was studied using acetyl salicylic acid as a drug model.

PURPOSE OF REVIEW: Optimal duration of dual antiplatelet therapy (DAPT) after coronary revascularization, in particular after drug-eluting stent (DES) implantation, is a matter of ongoing debate. RECENT FINDINGS: First generation of DES,... more

PURPOSE OF REVIEW:
Optimal duration of dual antiplatelet therapy (DAPT) after coronary revascularization, in particular after drug-eluting stent (DES) implantation, is a matter of ongoing debate.
RECENT FINDINGS:
First generation of DES, as compared with bare metal stents (BMS), reduce restenosis rates but increase very late stent thrombosis rates, thus requiring a prolonged course of DAPT. As a consequence, patients with high thrombotic and/or bleeding risk: have been systematically excluded from randomized trials comparing DES versus BMS; remain 'uncertain' DES candidates; should preferentially undergo BMS implantation at the time of percutaneous coronary intervention instead of DES. The Zotarolimus-eluting Endeavor Sprint Stent in Uncertain DES Candidates (ZEUS) trial is the first randomized study that demonstrated the superiority of the Zotarolimus-eluting Endeavor Sprint versus BMS in uncertain DES candidates who followed a personalized DAPT duration, which was tailored to patients's, not stent's, characteristics.
SUMMARY:
The results of the ZEUS trial may support a paradigm shift in our current understanding of the most proper use of DES in practice and should trigger further research in patients at high bleeding or thrombotic risk, who have been so far largely deprived of the potential benefit provided by DES.

Coronary artery anomalies (CAA) are congenital alterations in the origin, course and structure of the epicardial coronary arteries. The origin and proximal course of anomalous coronary arteries are the main predictors of severity. It... more

Coronary artery anomalies (CAA) are congenital alterations in the origin, course and structure of the epicardial coronary arteries. The origin and proximal course of anomalous coronary arteries are the main predictors of severity. It constitutes the second most frequent cause of sudden death of cardiovascular origin in competitive athletes and can be a cause of heart failure and death in infants. In this article, a case of a patient with unstable angina for 6 months finally diagnosed with the disease will be described. CASE REPORT: A 35-year-old female patient with no comorbidities was admitted to the Emergency Room with unstable angina. She had been undergoing an outpatient investigation for chest pain for 6 months. She performed a submaximal and positive treadmill test for myocardial ischemia, as well as coronary CT angiography (CT angiography) that showed an anomalous origin of the left main coronary artery, originating in the right coronary sinus and with a malignant path between the aorta and the pulmonary artery. Oral therapy with cardioselective beta-blockers (bisoprolol) and trimetazidine was started. It evolved in a refractory manner to drug treatment, with worsening of the angina with increased frequency and intensity, appearing at rest and with associated dyspnea (ccs4). She sought the emergency room and was hospitalized for surgical approach. For better visualization of the coronary bed, a preoperative catheterization was performed. The procedure performed by cardiovascular surgery was the bridge of the right internal mammary artery to the marginal artery and the left internal mammary artery to the anterior descending artery. The patient evolved without complications in the postoperative period. DISCUSSION: The diagnosis of AAC is a challenge, since patients are usually asymptomatic and physical examination does not reveal any changes. The American Heart Association considers cardiac CT angiography an adequate method for diagnosing CAA. Once diagnosed, AAC must be surgically corrected promptly to prevent complications and sequelae typical of the natural history of the disease. CONCLUSIONS: Although rare, it is a lethal condition if not diagnosed and treated early. After clinical confirmation of the disease, surgical therapy presents a viable option and, in general, with a good prognosis. As it is a rare disease, further studies are still needed to determine an effective screening and optimal treatment for each patient.

Myocardial bridge (MB) is a congenital abnormality of the coronary arteries characterized by the decrease in the coronary blood flow during systole due to the compression of the myocardial fibrils surrounding the epicardial coronary... more

Myocardial bridge (MB) is a congenital abnormality of the coronary arteries characterized by the decrease in the coronary blood flow during systole due to the compression of the myocardial fibrils surrounding the epicardial coronary artery in a certain segment. Although usually asymptomatic, medical therapy, percutaneous transluminal coronary angioplasty (PTCA), and rarely surgery may be necessary to relieve symptoms.

A 58-year old woman with an endocarditis of the aortic valve developed an acute anterior STEMI. Manual thrombus aspiration yields an embolus with a coccoid bacterium. The patient underwent immediate surgery with an aortic bioprosthesis... more

A 58-year old woman with an endocarditis of the aortic valve developed an acute anterior STEMI. Manual thrombus aspiration yields an embolus with a coccoid bacterium. The patient underwent immediate surgery with an aortic bioprosthesis and a coronary artery bypass graft (CABG) with a saphenous vein to the distal LAD.

BACKGROUND: Virtual histology intravascular ultrasound (VH-IVUS) imaging is an innovative tool for the morphological evaluation of coronary atherosclerosis. Evidence for the effects of statin therapy on VH-IVUS parameters have been... more

BACKGROUND:
Virtual histology intravascular ultrasound (VH-IVUS) imaging is an innovative tool for the morphological evaluation of coronary atherosclerosis. Evidence for the effects of statin therapy on VH-IVUS parameters have been inconclusive. Consequently, we performed a systematic review and meta-analysis to investigate the impact of statin therapy on plaque volume and its composition using VH-IVUS.
METHODS:
The search included PubMed, Cochrane Library, Scopus and Embase (through 30 November 2014) to identify prospective studies investigating the effects of statin therapy on plaque volume and its composition using VH-IVUS.
RESULTS:
We identified nine studies with 16 statin treatment arms and 830 participants. There was a significant effect of statin therapy in reducing plaque volume (standardized mean difference (SMD): -0.137, 95 % confidence interval (CI): -0.255, -0.019; P = 0.023), external elastic membrane volume (SMD: -0.097, 95 % CI: -0.183, -0.011; P = 0.027) but not lumen volume (SMD: -0.025, 95 % CI: -0.110, +0.061; P = 0.574). There was a significant reduction in fibrous plaque volume (SMD: -0.129, 95 % CI: -0.255, -0.003; P = 0.045) and an increase of dense calcium volume (SMD: +0.229, 95 % CI: +0.008, +0.450; P = 0.043), while changes in fibro-fatty (SMD: -0.247, 95 % CI: -0.592, +0.098; P = 0.16) and necrotic core (SMD: +0.011, 95 % CI: -0.144, +0.165; P = 0.892) tissue volumes were not statistically significant.
CONCLUSIONS:
This meta-analysis indicates a significant effect of statin therapy on plaque and external elastic membrane volumes and fibrous and dense calcium volumes. There was no effect on lumen volume, fibro-fatty and necrotic tissue volumes.

In this study, effect of different cutting methods and following normalization heat treatment on microstructure of 316L stainless steel tubings were investigated. 316L stainless steel is the most commonly used material for coronary stent... more

In this study, effect of different cutting methods and following normalization heat treatment on microstructure of 316L stainless steel tubings were investigated. 316L stainless steel is the most commonly used material for coronary stent production. Tubings were cut with laser cutting, plasma cutting, oxy-fuel cutting, water jet cutting and electrical discharge machining methods. Cut tubings were characterized by using Scanning Electron Microscope (SEM). Separate samples were prepared for heat treatment operation. 316L stainless tubings were cut with same methods and same parameters. Normalization heat treatment was applied to the samples. Heat treated tubings were characterized by using Scanning Electron Microscope. When results were evaluated, it was seen that laser cutting gives the best results rather than that of other cutting methods in terms of homogeneous microstructure, smoothness of cutting surface, a microstructure without oxidation and distortion etc.

AbstrAct Objective To evaluate the biological effect of microengineered stent grooves (MSG) on early strut healing in humans by performing optical coherence tomography (OCT) analysis 3 weeks following the implantation. Background In the... more

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

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

BACKGROUND: Stent thrombosis remains among the most feared complications of percutaneous coronary intervention (PCI) with stenting. However, data on its incidence and predictors are sparse and conflicting. We thus aimed to perform a collaborative systematic review on incidence and predictors of stent thrombosis. METHODS: PubMed was systematically searched for eligible studies from the drug-eluting stent (DES) era (1/2002-12/2010). Studies were selected if including ≥2000 patients undergoing stenting or reporting on ≥25 thromboses. Study features, patient characteristics, and incidence of stent thrombosis were abstracted and pooled, when appropriate, with random-effect methods (point estimate [95% confidence intervals]), and consistency of predictors was formally appraised. RESULTS: A total of 30 studies were identified (221,066 patients, 4276 thromboses), with DES used in 87%. After a median of 22months, definite, probable, or possible stent thrombosis had occurred in 2.4% (2.0%; 2....

Ischemic heart disease is the leading cause of death with acute coronary syndrome accounting for more than 30% of causes of mortality in the elderly population. The rate of growth of the older segment of... more

Ischemic heart disease is the leading cause of death with acute coronary syndrome accounting for more than 30% of causes of mortality in the elderly population. The rate of growth of the older segment of the population has increased exponentially and will become more pronounced in the future. Historically, there has been a paucity of clinical trials investigating the challenges and outcomes of more invasive treatment strategies such as percutaneous coronary intervention (PCI) for that very segment of the population. However, the safety, efficacy, and outcomes of PCI in the older population have started to receive more attention, leading to some changes in their trends. There are several factors that make interventional cardiologists more resistant to direct the elderly to PCI. Most of these challenging factors, such as the complexity of coronary lesions, frailty, hematological and vascular changes, are discussed in this review. In addition. more advanced technologies have been introduced to PCI platform such as second- and third-generations stents, several alternative approaches have been adopted like transradial approach and the usage of bivalirudin instead of heparin and GP IIb/IIIa inhibitor, and several imaging modalities have been optimized to assess patients’ outcome and prognosis more accurately. Several recent studies have shown better results when these strategies are adopted. The most recent recommendations regarding performing PCI in the elderly are also discussed in this review.

Inhibition of vascular smooth muscle cell (VSMC) proliferation by drug eluting stents has markedly reduced intimal hyperplasia and subsequent in-stent restenosis. However, the effects of antiproliferative drugs on endothelial cells (EC)... more

Inhibition of vascular smooth muscle cell (VSMC) proliferation by drug eluting stents has markedly reduced intimal hyperplasia and subsequent in-stent restenosis. However, the effects of antiproliferative drugs on endothelial cells (EC) contribute to delayed re-endothelialization and late stent thrombosis. Cell-targeted therapies to inhibit VSMC remodeling while maintaining EC health are necessary to allow vascular healing while preventing restenosis. We describe an RNA aptamer (Apt 14) that functions as a smart drug by preferentially targeting VSMCs as compared to ECs and other myocytes. Furthermore, Apt 14 inhibits phosphatidylinositol 3-kinase/protein kinase-B (PI3K/Akt) and VSMC migration in response to multiple agonists by a mechanism that involves inhibition of platelet-derived growth factor receptor (PDGFR)-β phosphorylation. In a murine model of carotid injury, treatment of vessels with Apt 14 reduces neointimal formation to levels similar to those observed with paclitaxel. Importantly, we confirm that Apt 14 cross-reacts with rodent and human VSMCs, exhibits a half-life of ~300 hours in human serum, and does not elicit immune activation of human peripheral blood mononuclear cells. We describe a VSMC-targeted RNA aptamer that blocks cell migration and inhibits intimal formation. These findings provide the foundation for the translation of cell-targeted RNA therapeutics to vascular disease.Molecular Therapy (2016); doi:10.1038/mt.2015.235.