Deciphering the source of an embolism is a common challenge encountered in stroke treatment. Carotid stenosis is a key source of embolic strokes. Carotid interventions can be indicated when a patient has greater than 50% stenosis in the carotid ipsilateral to the cerebral infarction, which is designated as the symptomatic carotid. However, there are often significant number of cases where carotid emboli travel contralaterally leading to ambiguity regarding which carotid is symptomatic. We use a patient-specific computational embolus-hemodynamics interaction model developed in prior works to conduct an in silico experiment spanning 30 heart-to-brain arterial models with differing combinations of bilateral severe and mild stenosis degrees. We used these models to study source-to-destination transport of thromboemboli released from left/right carotid disease sites, and cardiogenic sources. Across all cases considered, thromboemboli from left and right carotid sources showed non-zero contralateral transport. We also found that cardiogenic thromboemboli do not have an altered hemisphere distribution or distinct transport preference dependent on stenosis degree, thus potentially making the underlying etiology more cryptic. In patients with carotid stenosis or chronic occlusion ipsilateral to the area affected by stroke, we have demonstrated that the presence of contralateral stenosis can cause emboli that travel across the Circle of Willis (CoW) which can potentially lead to ambiguity when deciding which carotid is truly symptomatic.

The authors have declared no competing interest.

The Authors acknowledge funding support from National Institutes of Health Award: R21EB029736 for this study. This work utilized the Summit supercomputer, which is supported by the National Science Foundation (awards ACI-1532235 and ACI-1532236), the University of Colorado Boulder, and Colorado State University. The Summit supercomputer is a joint effort of the University of Colorado Boulder and Colorado State University.

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All quantitative embolus distribution data for this study have been shared through the Open Science Framework as part of project titled, "Dataset: Transport and Distribution of Embolic Particles in Human Vasculature", which can be accessed at: https://doi.org/10.17605/OSF.IO/CQKZT. All image-based modeling and computational hemodynamics simulations were conducted using the open source software package SimVascular. The image-based models (segmentations, pathlines) and computational hemodynamics data will be made available through the Vascular Model Repository associated with the SimVascular project and can be accessed at https://simvascular.github.io/. The sharing process with Vascular Model Repository is ongoing, and when the models have been shared, they will be linked to the dataset released on Open Science Framework linked above. For any data access issues, or for additional access to scripts and tools, please contact the corresponding author directly via email, or via the contact page on the research team's official website: https://www.flowphysicslab.com/.