Hemodynamic predictors for the onset of ischemic stroke due to carotid artery stenosis using a computational fluid dynamics analysis

Abstract

Background: Carotid artery stenosis is one of the major diseases responsible for atherosclerotic ischemic stroke. It is difficult to predict the onset of cerebral infarction by means of their known risk factors, including age, sex, diabetes mellitus, hypertension, dyslipidemia, and smoking habit. The carotid artery shape itself is a risk factor for stenosis, in which hemodynamics may be involved. We conduct an observational clinical study using a computational fluid dynamics (CFD) technique to investigate hemodynamic risk factors for carotid stenosis progression by enrolling and prospectively examining patients with carotid artery stenosis who underwent three-dimensional imaging of the carotid artery and carotid echocardiography. A total of 546 patients were registered in this study, which is designated the NHO Carotid CFD Study. To investigate hemodynamic predictors for the onset of ischemic stroke, we performed a multivariate analysis of 90 cases with carotid stenosis with an area stenosis rate of 50% to 85% among those enrolled in this clinical study, after adjustment for known risks. Methods: Patient-specific geometries of the carotid arteries were segmented and reconstructed from the volume data set of three-dimensional computed tomography angiography images in Digital Imaging and Communications in Medicine (DICOM) format, using Mimics and 3-matic (Materialise, Leuven, Belgium). Pulsatile blood flow was simulated using a CFD software package, ANSYS CFX (ANSYS, PA, USA), based on the Navier-Stokes equations for incompressible fluid. Individual vessel diameters and peak-systolic and end-diastolic velocities were measured with the Doppler ultrasound technique on common carotid arteries and internal carotid arteries of each patient to compute the corresponding flow rates. The stenotic carotid artery defined three regions: the “stenotic site” where the stenosis is present, the “proximal site” from the lower end of the stenosis to 10 mm proximal, and the “distal site” from the upper end of the stenosis to 10 mm distal. Results: Metrics related to proximal wall shear stress (WSS) disturbances, such as proximal transverse WSS (transWSS) (odds ratio (OR) 2.42, 95% confidence interval (95%CI) 1.32 to 5.00), proximal normalized transWSS (NtransWSS) (OR 1.71, 95%CI 1.02 to 3.03), and the stenotic/proximal ratio of transWSS (1/OR 1.59, 95%CI 0.39 to 0.88), had significant correlations with a history of cerebral infarction on the ipsilateral side of the stenotic artery. Conclusions: Our present analysis suggested that carotid arteries with the same degree of stenosis may be more likely to have a cerebral infarction in cases with higher transWSS in the proximal site than the stenotic one. In patients with these hemodynamic risks, underlying diseases should be controlled more strictly with imaging examinations at shorter intervals. This study was supported by a Grant-in-Aid for Japanese National Hospital Organization Multi-Center Clinical Research, and AMED under Grant Number JP15gm0810006h0301. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.