Effect of longitudinal anatomical mismatch of stenting on the mechanical environment in human carotid artery with atherosclerotic plaques

Influence of stent strut and its associated injury on thrombus formation: A dissipative particle dynamics study

Vascular stent intervention is a pivotal treatment for coronary atherosclerosis, though in-stent thrombosis remains a significant postoperative complication with an unclear underlying mechanism. This study utilized dissipated particle dynamics analysis to investigate the impact of stent and its injury on platelet behavior. The findings suggest that thrombus formation upstream of the stent is mainly initiated by upstream arterial injury, which leads to increased platelet accumulation and activation in that area. While thrombosis downstream of the stent is more directly influenced by the stent itself. The morphology and size of in-stent thrombosis can vary significantly due to the different contributions of the stent and underlying injuries. Additionally, the volume of in-stent thrombosis is affected by the extent of the injury and the viscosity of platelets, showing a notable increase in volume with the lengthening of the injury area and rise in platelet viscosity. This study provides a novel theoretical framework for optimizing stent placement strategies and structural designs by examining the effects of stent struts and associated injuries on thrombus formation.

The differences between surface degradation and bulk degradation of FEM on the prediction of the degradation time for poly (lactic-co-glycolic acid) stent

The degradation time is a crucial factor in evaluating the performance of poly (lactic-co-glycolic acid) (PLGA) stents. Bulk degradation mode was commonly used to analyze the stent degradation behavior by finite element approach. However, the PLGA stents may present surface degradation more than bulk degradation under certain conditions, which will greatly affect the degradation time after implantation. In this study, the degradation processes of the poly (lactic-co-glycolic acid) stent were reproduced utilizing finite element analysis. Both bulk degradation and surface degradation modes were considered. The correlation between tensile stress and degradation rate was investigated. The degradation time was analyzed selectively. The stress distribution, fracture, and mass loss were also compared between bulk degradation mode and surface degradation mode. The simulation results showed that, in both evolution modes, the degradation began at the 'peak-valley' region and fracture occurred at the cross of links and rings. Additionally, high levels of Von-Mises stress were observed in these two regions. Compared with bulk degradation, the fracture time of the stent was delayed by 63% in the surface degradation mode. In conclusion, the mass loss rate and scaffolding period showed great differences between surface degradation and bulk degradation. Based on this study, it is suggested that bulk degradation mode is not applicable to the case of inadequate water uptake mode, such as the tracheal stent degradation process. More experimental research should be carried out to accurately predict the scaffolding period after implantation. The mechanical properties of the fracture zone should be strengthened.

Effects of different positions of intravascular stent implantation in stenosed vessels on in-stent restenosis: An experimental and numerical simulation study

Percutaneous coronary intervention (PCI) has been widely used in the treatment of atherosclerosis, while in-stent restenosis (ISR) has not been completely resolved. Studies have shown that changes in intravascular mechanical environment are related to ISR. Hence, an in-depth understanding of the effects of stent intervention on vascular mechanics is important for clinically optimizing stent implantation and relieving ISR. Nine rabbits with stenotic carotid artery were collected by balloon injury. Intravascular stents were implanted into different longitudinal positions (proximal, middle and distal relative to the stenotic area) of the stenotic vessels for numerical simulations. Optical coherence tomography (OCT) scanning was performed to reconstruct the three-dimensional configuration of the stented carotid artery and blood flow velocity waveforms were collected by Doppler ultrasound. The numerical simulations were performed through direct solution of Naiver-Stokes equation in ANSYS. Results showed that the distributions of time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) and relative residual time (RRT) in near-end segment were distinctively different from other regions of the stent which considered to promote restenosis for all three models. Spearman rank-correlation analysis showed a significant correlation between hemodynamic descriptors and the stent longitudinal positions (r_TAWSS = -0.718, r_OSI = 0.898, r_RRT = 0.818, p < 0.01). Histology results of the near-end segment showed neointima thickening deepened with the longitudinal positions of stent which was consistent with the numerical simulations. The results suggest that stent implantation can promote restenosis at the near-end segment. As the stenting position moves to distal end, the impact on ISR is more significant.

Carotid Artery Stenting in Asymptomatic Carotid Artery Stenosis: JACC Review Topic of the Week

The advance of therapies to reduce the stroke impact of asymptomatic carotid artery stenosis has proved difficult over the last decade. Disagreement concerning the underlying randomized control trials has limited entry into the care arena of endovascular therapies. Recently, advances in percutaneous therapies for carotid artery disease have been reported and provide a substantial database supporting the further incorporation of endovascular-based therapies in patients who need revascularization and meet selection criteria. With a second randomized control trial now published, it is time for a re-evaluation of endovascular therapy as a component of carotid artery care. This review describes the advances in the field in the last 5 years, clarifying the current position of these therapies in the care of the patient with asymptomatic carotid artery disease.