Vascular restoration therapy and bioresorbable vascular scaffold

Abstract

This article describes the evolution of minimally invasive intervention technologies for vascular restoration therapy from early-stage balloon angioplasty in 1970s, metallic bare metal stent and metallic drug-eluting stent technologies in 1990s and 2000s, to bioresorbable vascular scaffold (BVS) technology in large-scale development in recent years. The history, the current stage, the challenges and the future of BVS development are discussed in detail as the best available approach for vascular restoration therapy. The criteria of materials selection, design and processing principles of BVS, and the corresponding clinical trial results are also summarized in this article.

A review on biodegradable materials for cardiovascular stent application

“…Magnesium alloys have outstanding specific strength [122], hot formability [123], good cast ability [124], and tremendous sound damping capabilities, good electromagnetic interference shielding [125], excellent machinability [126], and recyclability. As well, magnesium alloys have specific density (1.74-2 g/cm 3 ) and Young's modulus (41)(42)(43)(44)(45) GPa) most close to those (1.8-2.1 g/cm 3 , 3-20 GPa) of human body's bone in the case for commonly used artificial implant materials. Thus, in orthopedic and bone repairing or replacement applications magnesium alloys are predominantly superior to any other metallic or polymer implants [124,127].…”

“…Summary of the design and structure of clinically tested bioresorbable scaffold[34][35][36][37][38][39][40][41][42][43][44][45][46][47] …”

Reduction in the Corrosion Rate of Magnesium and Magnesium Alloy Specimens and Implications for Plain Fully Bioresorbable Coronary Artery Stents: A Review

“…A bioresorbable stent has a number of potential advantages over a durable stent [30] [41], several of which are outlined here. The former type of stent 1) may be monitored with a non-invasive technique, such as advanced multi-slice computed tomography or magnetic resonance imaging, without causing any metallic artifacts; 2) might restore late expansive remodeling, favorable vascular dynamics, adaptive shear stress, and late lumen enlargement, each of which may contribute to decreased rates of neo-atherosclerosis, in-segment restenosis (ISR), and in-stent thrombosis (ST); 3) has low possibility for strut fracture; and 4) obviates the need for prolonged DAPT, thus minimizing the risk for bleeding in high-risk patients such as elderly ones and those on oralanti-coagulants [39] [40] [41] [42] [43]. Furthermore, after resorption of a bioresorbable stent, 1) there will be full restoration of vascular architecture, endothelium function within the stented area of the artery segment, vasomotion, distensibility, pulsatility, and mechano-transduction; 2) a thick circumferential fibrous layer similar to a thick fibrous cap will be left behind, which may facilitate reduction of the plaque burden; and 3) there will be the option for repeat revascularization (via CABG or PTCI) in or outside the area of original stenting, an option that is particularly important in certain cases, such as those involving bifurcating lesion(s) [47] [48].…”

“…In a plain FBRS, the scaffold is made of Mg or a Mg alloy, whereas, in a coated FBRS, the scaffold, made of either a Mg alloy or a bioresorbable polymer, is coated with a bioresorbable polymer in which an anti-proliferative drug is embedded. There is a growing body of reviews of the literature on bioresorbable stents exclusively [33]- [43], but only very few cover Mg/Mg alloy FBRSs and, of these, fewer still include any coverage of what, arguably, is the most important shortcoming/challenge of this type of stent, which is high corrosion rate (resulting in rapid resorption) [33] [34] [35] [36]. However, 1) in the review by Boland et al [33], the subject is degradation models for both metallic and polymeric components and their application to both Mg-based and polymer-based bioresorbable stents;…”

Automated Segmentation of Bioresorbable Vascular Scaffold Struts in Intracoronary Optical Coherence Tomography Images

“…The transition from a focus on invasive bypass-surgery to minimally invasive interventions [3] requires holistic understanding of the effect of different device types on patient cardiovascular function. Metallic stents are accompanied by long-term issues: the relatively inflexible nature of the stent obstructs natural remodeling of the artery and the vasomotion of the artery is not normal [2], [4], [5]. In contrast, BVS hold the promise of enabling early restoration of endothelial functioning, normal vasomotion, and natural remodeling of the coronary artery [6].…”