Stent Case Study

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Implantation of a stent within a coronary artery alters the local hemodynamics modifying the shear stress upon the endothelium. 14 Low endothelial shear stress causes a phenotypic change in which can induce a phenotypic switch in the smooth muscle cells from contractile to secretory as well as increase migration into the intima and proliferation. 15 Overall, regular or high endothelial shear stress maintains the contractile phenotype of the smooth muscle cells therefore inhibiting neointimal formation. 15 Therefore, in addition to the immune response activated by the vascular injury, the hemodynamics of the stent will also impact the neointimal growth. 14
The Absorb BVS stent protrudes into the lumen, thus altering hemodynamics and producing
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hypothesize that the inflammatory response and healing process derived from implantation may drive the neointimal growth for the initial 6 months as evidenced by the significant increase in the average neointimal area. 1 By 6 months, Bourantas et al. postulate that the healing process is almost over, thus there is no significant neointimal formation. 1 The comparable diameter stenosis demonstrated between 6 months and 2 years in the Cohort A study 16 and the lack of late lumen loss between year 1 and year 3 in the Cohort B study 10 correlates with the lack of significant neointimal formation between 6 months and 12 months. 1 If the major healing response nears completion by 6 months post-implantation, BVS would yield a significant benefit over DES. Restenosis of DES has been implicated with late wound healing and incomplete endothelialization. 2 Both Nakazawa et al. and Yoneda et al. emphasizes that the drug’s mechanism results in delayed wound healing which can lead to restenosis. 2,17 Restenosis in bare metal stents, in contrast, is suspected to undergo a different mechanism, potentially shear stress, and occurs much later. 17 In comparison to BVS, which by four years has undergone complete bioresorption, in a porcine model, 3 and potentially nears completion of healing by 6 months, 1 the use of BVS should decrease the chance of …show more content…
The effects of endothelial shear stress and the immune response to the implantation on neointimal formation offers an interesting outcome when coupled with the bioresorbable vascular scaffold. The transient nature of these scaffolds within the vasculature should potentially decrease the likelihood of restenosis observed with metal-based stents. Together the neointimal formation surround the scaffold and the new connective tissue replacing the scaffold overtime produce a thick fibrous plaque that increases plaque stability helping prevent restenosis or rupture of the plaque. Due to the transient nature of the scaffold, proper vascular function may be returned as the resorptive process occurs, thus potentially regaining vasomotion in the stent region. Lastly, the benefits of this technology have hinted at the potential in which BVS may be able to improve upon current treatments for in-stent restenosis. Ultimately, the remarkable potential of the bioresorbable vascular scaffold has in regards to decreasing negative outcomes associated with drug-eluting stents propels it towards being a widely investigated

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