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Endovascular Implants
Published in Wilmer W Nichols, Michael F O'Rourke, Elazer R Edelman, Charalambos Vlachopoulos, McDonald's Blood Flow in Arteries, 2022
Elazer Edelman, Lambros Athanasiou, Farhad Rikhtegar Nezami
Pharmacological solutions including systemic dual antiplatelet therapy (DAPT) reduced stent thrombosis but with no discernible effects on restenosis (Mehta and Yusuf, 2000; Woods and Marks, 2004) and, with each increment in systemic dosing, side effects emerged. The idea of local drug delivery tied to endovascular implants emerged to provide ample dosing at the site of injury and widen the therapeutic window (Edelman et al., 1990, 1993). Thus drug-eluting stents (DES) were developed where an antiproliferative drug carrier was coated on the metallic backbone of the device to minimize neointimal growth, prevent restenosis and reduce reintervention (Drachman et al., 2000). The new challenge, though, was to achieve safe and effective DES with appropriate device, suitable release kinetics and sufficient drug embedment (Edelman and Rogers, 1998; Welt et al., 2000). In search of drugs with avid tissue binding and high tissue retention, paclitaxel and sirolimus were first introduced to the market with outstanding vascular retention and prolonged biological effects (Woods and Marks, 2004; Creel et al., 2000; Hwang et al., 2003; Hwang and Edelman, 2002; Lovich et al., 2001). In 2003, the Cypher sirolimus-eluting stent and a year later the Taxus paclitaxeleluting device further transformed interventional medicine.
Acute coronary syndromes
Published in Henry J. Woodford, Essential Geriatrics, 2022
Patients may require transfer to a centre that can provide PCI. Ideally, STEMI is diagnosed pre-hospital and the initial ambulance transfer is to a PCI centre. To achieve this, an ECG must be performed at first contact with a healthcare professional. Trans-radial access for PCI is preferred due to lower local bleeding risk. Coronary stenting, with drug-eluting stents, is recommended rather than angioplasty.12 A parenteral anticoagulant, such as unfractionated heparin, is used around the time of the procedure. Initial post-procedure management should be on a coronary care unit. If PCI fails, for example, due to unsuitable vascular anatomy, then emergency surgical coronary artery bypass grafting may be considered. Older age is associated with increased coronary artery calcification, which increases the risk of complications such as artery dissection and stent thrombosis. Older people also tend to have more extensive arterial disease. Renal impairment increases the risk of adverse effects with the contrast used during PCI.
The cardiovascular system
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
Mary N Sheppard, C. Simon Herrington
Unfortunately, the early use of balloon angioplasty led to thrombosis and rapid restenosis of the coronary artery due to intimal healing with smooth muscle cell hyperplasia. The application of a metallic stent to keep the coronary artery open improved the long-term patency of the vessels. The complication of stent thrombosis was overcome with the introduction of effective anti-platelet therapy. The introduction of drug-eluting stents, which slow smooth muscle growth, helped to reduce restenosis. Primary angioplasty with stent insertion is now the treatment of choice for patients with acute myocardial infarction. Late stent thrombosis can occur and histopathological data implicate a contributory allergic or hypersensitivity component.
Clinical characteristics, risk factors, and prognostic analyses of coronary small vessel disease: a retrospective cohort study of 986 patients
Published in Postgraduate Medicine, 2023
Yue Chen, Xiao Cui, Liujun Jiang, Xiaolei Xu, Chaoyang Huang, Qiwen Wang
In terms of PCI intervention procedures, the number of PCIs per capita in CSVD patients was significantly higher than in non-CSVD patients (1.32 vs. 1.09, P < 0.001). Moreover, the average number of stents (2.63 vs. 1.50, P < 0.001) and the number of rotational atherectomies (3.9% vs. 1.0%, P = 0.002) in CSVD patients were significantly higher than in non-CSVD patients, while the rate of complete revascularization was significantly lower (70.1% vs. 85.1%, P < 0.001). This evidence demonstrates that CSVD is more difficult to operate compared to non-CSVD. Although newer-generation drug-eluting stents are used for interventional therapy, restenosis remains unavoidable [23]. Small vessels are typically subjected to high thrombotic burdens, potentially predisposing individuals to acute or subacute thrombosis and worse outcomes post-stent implantation [23,40]. According to the postoperative follow-up, the restenosis ratio in CSVD patients was significantly higher than in non-CSVD patients (6.5% vs. 3.2%, P = 0.019). The incidence of MACE events in CSVD patients was significantly higher than in non-CSVD patients (8.1% vs. 3.2%, P = 0.01). Cumulative MACE-free survival analysis in CSVD patients also confirmed that the long-term prognosis was worse than in non-CSVD.
Demonstration of ultrasound-mediated therapeutic delivery of fibrin-targeted pioglitazone-loaded echogenic liposomes into the arterial bed for attenuation of peri-stent restenosis
Published in Journal of Drug Targeting, 2023
Melvin E. Klegerman, Melanie R. Moody, Shao-Ling Huang, Tao Peng, Susan T. Laing, Vijay Govindarajan, Delia Danila, Amirali Tahanan, Mohammad H. Rahbar, Deborah Vela, Curtis Genstler, Kevin J. Haworth, Christy K. Holland, David D. McPherson, Patrick H. Kee
Stent implantation is effective for the prevention of luminal loss in flow limiting atherosclerotic lesions [1,2], however, late luminal loss due to in-stent and peri-stent atheroma restenosis remains an important clinical challenge [2]. Angioplasty and stent implantation cause acute arterial injury through platelet and leukocyte activation, smooth muscle cell proliferation, and resultant neointimal growth [3,4]. Stents that deliver antiproliferative agents such as sirolimus and paclitaxel are effective against some neointimal proliferation, but late stent thrombosis remains an issue due to chronic inflammation, impaired reendothelialisation and delayed vascular healing [5,6]. In-stent neoatherosclerosis results from the accumulation of lipid-laden foamy macrophages with or without necrotic core formation and/or calcification within the neointima, and has been implicated in in-stent restenosis after percutaneous interventions [7–10]. Furthermore, despite the success of drug-eluting stents to reduce in-stent restenosis in coronary artery lesions, clinical trials studying the use of drug-eluting stents in peripheral arterial disease have reported disappointing results [11,12]. Novel methodologies to stabilise the vascular bed at the time of stent implantation are required.
An overview of PLGA in-situ forming implants based on solvent exchange technique: effect of formulation components and characterization
Published in Pharmaceutical Development and Technology, 2021
Tarek Metwally Ibrahim, Nagia Ahmed El-Megrab, Hanan Mohammed El-Nahas
On the other hand, polymeric implant systems are specific-shaped masses that are composed of a biocompatible biodegradable or non-biodegradable polymer. They are generally implanted by using an injector device and must be finally removed in case of utilizing a non-biodegradable polymer such as Nexplanon® and Iluvien® (Stewart et al. 2018). Ozurdex® is rod-shaped biodegradable PLGA-based implants that depend on Allergan’s Novadur® technology and are utilized for the treatment of diabetic macular edema via intravitreal dexamethasone administration (Jervis 2017). Drug-eluting stents are specific double-action systems generally consisted of a stent as the device component and a drug-containing coating as the drug component. As an example, Coroflex® ISAR NEO can provide a prolonged release of sirolimus, embedded in the drug-eluting coating, used for prevention of myointimal proliferation and reduction of restenosis with the assistance of the mechanical support of the stent that can maintain the open vasculature and arterial patency (Al-Jawadi et al. 2018).