Coronary Stent

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.

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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 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.

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.

Objective: Vascular closure devices (VCDs), such as the Angio-Seal, a three-component hemostatic plug, have greatly facilitated the routine clinical practice in the catheterization laboratory. The manufacturer recommends a local angiogram before Angio-Seal deployment. However, from the outset, we employed a simplified routine of deploying this VCD, i.e. without use of local angiography. Methods: The Angio-Seal was employed without a preceding femoral arteriogram over 8 years in 2074 consecutive patients, 72% presenting with acute coronary syndromes and subjected to coronary angiography (n = 1032) or PCI n = 1042) via a transfemoral approach with use of heparin and dual antiplatelet therapy. Results: Deployment of the VCD was successful in 99.4%. Complete hemostasis was obtained in 98% of cases. In 14 patients, Angio-Seal deployment failed. Mean time for placement of Angio-Seal was <1 min, to-hemostasis 1 min, and to-mobilization 3 h. Only 3 (0.15%) patients had a major complication with vessel occlusion that required emergent vascular surgery with a successful outcome. Two patients developed a local pseudoaneurysm treated with ultrasonography-guided compression. Six small and 4 large inguinal hematomas (one requiring blood transfusion) and 5 cases of retroperitoneal bleeding (one requiring blood transfusion) were recorded. Conclusion: Deployment of Angio-Seal without use of local angiography was efficacious and safe, characterized by a high success rate of deployment and hemostasis with few correctable complications in a large patient cohort undergoing transfemoral catheterization for PCI and non-PCI procedures under anticoagulation and antiplatelet drug therapy. VCD reduced the time-to-hemostasis and time-to-mobilization and minimized the incidence of complications.

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 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 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  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) 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.