Carotid Bifurcation With Tandem Stenosis—A Patient-Specific Case Study Combined in vivo Imaging, in vitro Histology and in silico Simulation

Abstract

A patient-specific carotid bifurcation with tandem stenosis found at both internal carotid artery (ICA) and common carotid artery (CCA) was studied. The in vivo pre-carotid endarterectomy (pre-CEA) multi-spectral magnetic resonance imaging (MRI) were performed and in vitro post-CEA carotid plaque tissue sample was collected. MR imaging data and tissue sample staining histology were used to recognize the plaque components. Further, the computational fluid dynamics (CFD) were performed on four MR-based reconstructed 3D carotid bifurcation models (the patient-specific geometry with tandem stenosis and three presumptive geometries by removing the stenosis part). The flow and shear stress behavior affected by the tandem stenosis was analyzed. From the results of MR segmentation and histology analysis, plaque lipid pool and calcification were found at both ICA and CCA. From the result of CFD simulation, the flow shear stress behavior suggested the tandem stenosis as a more “dangerous” situation than a single-stenosis artery. Besides, the CFD results deduced that the stenosis at the CCA location formed initially and led to the subsequent formation of stenosis at ICA. This study suggests that when planning CEA, CFD simulation on the presumptive models could help clinicians to estimate the blood flow behavior after surgery. Particular attention should be paid to the case of tandem stenosis, as the local hemodynamic environment is more complex and treatment of one stenosis may lead to a variation in the hemodynamic loading on the second plaque, which may result in either a higher risk of plaque rupture or restenosis.

Case Report: Evaluating Biomechanical Risk Factors in Carotid Stenosis by Patient-Specific Fluid-Structural Interaction Biomechanical Analysis

“…Furthermore, as suggested in a previous study [10], the flexible vessel wall makes the WSS result more convincing. By comparing with the conclusion from a previous CFD-only study [19], there were some differences found on the values of hemodynamic parameters. But it was noticed the pattern of the abnormal area with low WSS, high OSI, and RRT was similar in both FSI and CFD-only models, which proved the CFD-only model could be an effective alternative if only hemodynamic factors were required.…”

“…RRT is marked by low WSS magnitude and high oscillatory WSS [17]. Normally, a low TaWSS, high OSI, and RRT are used as indicators of the atherogenesis region [18,19]. In the structural analysis participant, the maximum principle stress (Stress-P1) was analysed.…”

“…It was a potential risk of further developing the current plaque and becoming a high-risk plaque. Investigation of Patient II Patient II previously has been studied by using CFDonly presumptive models [19]. This patient had severe stenosis in both CCA and ICA, where the ICA stenosis consisted of 2 small stenoses and had complex partitions of plaque.…”

“…Following our previous CFD-only study [19], we further introduced the FSI model to study this patient case. In the FSI model, the finding from the previous CFDonly model was reiterated; the current plaque might further develop if the stenosis was not removed.…”

The Anastomotic Angle of Hemodialysis Arteriovenous Fistula Is Associated With Flow Disturbance at the Venous Stenosis Location on Angiography

“…In addition, our research revealed an interconnected link among the anastomotic angle, the flow disturbance, and the stenotic site; specifically, when compared to the other locations in the AVF, blood flow disturbance at the stenotic site shows the strongest correlation with the AV anastomotic angle. The reconstructed patient-specific geometrical model has become a powerful tool to investigate disturbed hemodynamics and stenosis in cardiovascular diseases ( Salman et al, 2019 ; Wang et al, 2019 ).…”