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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
In the absence of a metallic backbone, available polymeric bioresorbable stents (BRS) rely on PLA and PLGA polymers used in bioresorbable coatings. Given the lower strength of the material, early polymeric BRS were designed with substantially thicker struts than contemporary durable stents with high strut surface area/vessel surface area ratio to alleviate the suboptimal radial support and variable deployment (Cassese et al., 2015; Moravej and Mantovani, 2011; Wang et al.) (Figure 23.6 [A]). These thicker struts, as previously discussed, increased the vascular injury, induced flow disruption and triggered platelet activation and deposition. Inherent material characteristics and design of device obliged postdilatation to resolve device recoil, underexpansion and malapposition. Lesion preparation was also warranted in highly calcified plaques to minimize the fracture risk of fragile polymeric struts. Furthermore, there were concerns with significant increase of late stent thrombosis due to fracture and fatigue of BRS struts as the device dissipated over time. The aggregate of these shortcomings led to several catastrophic failure reports in clinics, including pronounced rate of stent thrombosis (Figure 23.6 [B]) (Ali et al., 2018; Capodanno et al., 2015; Cassese et al., 2015; Sorrentino et al., 2017), and a therapy once heralded as the next paradigm shift in percutaneous vascular interventional technology was withdrawn from clinical availability.
Advances in stent technology
Published in John Edward Boland, David W. M. Muller, Interventional Cardiology and Cardiac Catheterisation, 2019
Smriti Saraf, Paul Bhamra-Ariza
Another important component of the modern DES is the polymer. This is a drug carrier molecule that stores a therapeutic agent (drugs that essentially inhibit smooth muscle activation and replication, the main processes involved in ISR), as well as allowing the drug to diffuse into the vascular tissue in a controlled fashion. Polymers have been reported to result in an inflammatory effect leading to thrombosis.14 To overcome this problem, newer stents have been designed to be polymer-free or to use bioresorbable polymers in the hope that as a polymer degrades, endothelial healing improves, and so polymer-free or bioresorbable stent designs may reduce the future risk of ISR or acute ST.
Degradable, biodegradable, and bioresorbable polymers for time-limited therapy
Published in Yoshinobu Onuma, Patrick W.J.C. Serruys, Bioresorbable Scaffolds, 2017
This rather recent family of polymers exploits the hydrolytic cleavage of anhydride and ester functions that are present in repeating units [22]. The anhydride functions are easily cleaved and full degradation after 90 days was observed in vitro when R = (CH2)8. Degradation releases salicylate, a well-known anti-inflammatory compound. Polymers of this family are involved in some sustained drug delivery systems and also to make a bioresorbable stent [23].
Drug loaded implantable devices to treat cardiovascular disease
Published in Expert Opinion on Drug Delivery, 2023
Masoud Adhami, Niamh K. Martin, Ciara Maguire, Aaron J. Courtenay, Ryan F. Donnelly, Juan Domínguez-Robles, Eneko Larrañeta
The use of biodegradable DES offers several advantages over conventional stents. The presence of metals or polymers in the blood vessels can initiate an inflammatory response, prevent healing, and can cause endothelial dysfunction. These outcomes have been linked to the late thrombosis restenosis occurrence in DES [42]. Furthermore, loss of vasomotion, problems in revascularisation of the target vessel, and stent fracture can all occur [54]. Non-bioresorbable stents also limit the use of magnetic resonance imaging, whereas bioresorbable seems to be compatible with MRI and computed tomography imaging, which can hold an important place in diagnostics [54,90]. The use of bioresorbable stents also allows for the recovery of vasomotion, an important process in tissue perfusion, and the possibility of positive remodeling [91,92].
Bioresorbable polymer and durable polymer metallic stents in coronary artery disease: a meta-analysis
Published in Expert Review of Cardiovascular Therapy, 2021
Tanveer Mir, Layla Shanah, Usman Ahmad, Yasar Sattar, Bhavin Chokshi, Ankita Aggarwal, Preeya Prakash, Hassan Bin Attique, Khalid Hamid Changal, Kartik Kumar, Chadi Alraies, Waqas T Qureshi, Luis Afonso
The cohort treated with BPS had comparable results in regard to cardiac death, TVR, stent thrombosis, target vessel MI, and all-cause MI to the cohort treated with DPS. Higher TVR for BPS was observed for a follow-up duration of more than 5 years. The outcomes for patients treated with BPS and DPS were comparable for variable durations of DAPT. In conclusion, more research will be required to evaluate long-term follow-up results for the bioresorbable stent types.
Durable polymer everolimus-eluting stents: history, current status and future prospects
Published in Expert Review of Medical Devices, 2020
Juan J. Rodríguez-Arias, Luis Ortega-Paz, Salvatore Brugaletta
In summary, the possible benefits of short DAPT and new antiproliferative drugs, added to the efficacy of current DP-EES, make these stents a safe and polyvalent solution in the catheterization laboratory. However, the results of ongoing trials with resorbable materials will tell if the a new bioresorbable stent generation will disappear forever or it will be just another chapter in the history of stents.