Determining the specific hemodynamics related to clot formation and subsequent stroke in subjects with carotid webs

Project Summary/Abstract Carotid webs (CaW) are intraluminal projections into the internal carotid artery bulb that represent the underlying etiology in many ‘cryptogenic’ stroke cases in younger patients. Although CaW only cause minor stenosis, these lesions are associated with thromboembolism that is resistant to standard antiplatelet therapy, and hence have a high rate of recurrent stroke risk. Due to the lack of knowledge of the hemodynamic parameters underlying CaW-induced thromboembolism, there is a no consensus on how to manage patients with CaW. This is particularly important in incidentally discovered CaW. The goal of this project is to define the specific, quantitative values for hemodynamics parameters in the region where a clot forms. To achieve this goal, we will use a unique dataset where we have 30 subjects where imaging by computed tomography angiography (CTA) was done when a clot was present on the web and when clot was absent. Combining these CTA images with computational fluid dynamics (CFD) simulations we can determine specific, quantitative hemodynamic parameters at the exact location where a clot formed. Our preliminary studies using CFD simulations suggest that CaW produce low shear rates, which are associated with red clot formation. Prior work on CaW has been limited by sample size or over-simplification of CaW geometries. We propose to use a databases of CaW patients from 5 centers to obtain a robust sample size. The use of geometries based on CTA will make the simulations patient-specific. Successful completion of the project will significantly advance our understanding of the mechanism of thrombogenesis and stroke in these patients as well as provide hemodynamic metrics for a clinical classification system of CaW that provides patient-specific stroke risk.