Haemodynamic impact of stent-vessel (mal)apposition following carotid artery stenting: mind the gaps!
G De Santis1, M Conti, B Trachet
1BiTech-bioMMeda, Ghent University, Ghent, Belgium. gianluca.desantis@ugent.be
Insights
Computational analysis of carotid artery stenting (CAS) reveals how stent placement impacts blood flow. Poor stent apposition can cause abnormal shear forces, potentially leading to adverse events like thrombosis.
Area of Science:
- Biomedical Engineering
- Medical Imaging
- Computational Fluid Dynamics
Background:
- Carotid artery stenting (CAS) is a less invasive option than endarterectomy but faces limitations due to post-stenting complications.
- Hemodynamic factors in stented vessels may influence endothelial responses, contributing to restenosis and thrombosis.
- In vivo measurement of flow-related shear forces on endothelium is limited by current non-invasive imaging resolution.
Purpose of the Study:
- To develop a computational framework for precise determination of wall shear stress (WSS) after carotid artery stenting.
- To investigate the hemodynamic consequences of stent implantation in a mildly stenosed carotid artery model.
Main Methods:
- Utilized angiographic CT and micro-CT scans to create a 3D model of the stented carotid artery.
- Performed in silico stent deployment using finite element analysis.
- Simulated blood flow with defined inlet pressure and outlet impedance boundary conditions.
Main Results:
- Identified atheroprone regions characterized by low time-average WSS and high relative residence time.
- Localized these regions to areas of stent malapposition and strut interconnections.
- Observed that unapposed stent struts in the external carotid artery ostium disrupt flow and generate abnormal shear forces.
Conclusions:
- Computational analysis provides crucial insights into hemodynamic alterations post-CAS.
- Stent malapposition is linked to adverse hemodynamic conditions that may promote thromboembolic events.
- This in silico approach aids in understanding and potentially mitigating CAS complications.
Abstract:
Carotid artery stenting (CAS) has emerged as a minimally invasive alternative to endarterectomy but its use in clinical treatment is limited due to the post-stenting complications. Haemodynamic actors, related to blood flow in the stented vessel, have been suggested to play a role in the endothelium response to stenting, including adverse reactions such as in-stent restenosis and late thrombosis. Accessing the flow-related shear forces acting on the endothelium in vivo requires space and time resolutions which are currently not achievable with non-invasive clinical imaging techniques but can be obtained from image-based computational analysis. In this study, we present a framework for accurate determination of the wall shear stress (WSS) in a mildly stenosed carotid artery after the implantation of a stent, resembling the commercially available Acculink (Abbott Laboratories, Abbott Park, Illinois, USA). Starting from angiographic CT images of the vessel lumen and a micro-CT scan of the stent, a finite element analysis is carried out in order to deploy the stent in the vessel, reproducing CAS in silico. Then, based on the post-stenting anatomy, the vessel is perfused using a set of boundary conditions: total pressure is applied at the inlet, and impedances that are assumed to be insensitive to the presence of the stent are imposed at the outlets. Evaluation of the CAS outcome from a geometrical and haemodynamic perspective shows the presence of atheroprone regions (low time-average WSS, high relative residence time) colocalised with stent malapposition and stent strut interconnections. Stent struts remain unapposed in the ostium of the external carotid artery disturbing the flow and generating abnormal shear forces, which could trigger thromboembolic events.
