Shear stress rosettes capture the complex flow physics in diseased arteries

Area of Science:

• Cardiovascular Mechanobiology
• Biomedical Engineering
• Fluid Dynamics

Background:

• Wall shear stress (WSS) is critical in arterial health and disease.
• Existing metrics like TAWSS, OSI, and transWSS offer limited insights into complex flow dynamics.
• A need exists for advanced methods to visualize and quantify temporal WSS variations.

Purpose of the Study:

• To introduce shear rosettes as a graphical tool for WSS visualization.
• To define new WSS-derived metrics, including the anisotropy ratio (AR).
• To analyze flow physics in patient-specific arterial geometries using shear rosettes.

Main Methods:

• Developed shear rosettes for mapping temporal WSS changes over a cardiac cycle.
• Quantified mean WSS, OSI, and transWSS from rosette features (centroid, splay, width).
• Defined and calculated the anisotropy ratio (AR) from rosette dimensions to assess flow bi-directionality.

Main Results:

• Shear rosettes effectively visualized temporal WSS variations and flow phenomena like secondary flows and reversals.
• Rosette shape directly correlated with flow characteristics.
• The new anisotropy ratio (AR) captured flow bi-directionality.
• Distinct flow dynamics in ascending aorta (AA) and internal carotid artery (ICA) were clearly reflected in rosette shapes and metrics.

Conclusions:

• Shear rosettes provide an intuitive graphical representation of WSS and complex flow dynamics.
• The anisotropy ratio (AR) offers a novel metric for quantifying flow bi-directionality.
• This approach enhances the understanding of WSS in health and disease, particularly in patient-specific arterial models.