Evaluation of Endothelial Shear Stress and 3D Geometry as Factors Determining the Development of Atherosclerosis and Remodeling in Human Coronary Arteries in Vivo

TLDR

Rheologic factors such as shear stress are implicated in plaque predilection sites, yet no in vivo 3D shear stress data exist for human coronary arteries. The study introduces a nondestructive 3D reconstruction and CFD technique to calculate endothelial shear stress in vivo, enabling repeated measurements to track atherosclerosis progression. The technique reconstructs 3D coronary geometry, computes wall shear stress via CFD, and measures wall thickness, curvature, and plaque location relative to the principal curvature plane. Wall thickness inversely correlates with shear stress across velocity levels, with inner curvature exhibiting thicker walls and lower shear stress, while outer curvature shows thinner walls and higher shear stress; these data provide first in vivo evidence that low shear stress promotes atherosclerosis.

Abstract

Abstract The predilection sites of atherosclerotic plaques implicate rheologic factors like shear stress underlying the genesis of atherosclerosis. Presently no technique is available that enables one to provide 3D shear stress data in human coronary arteries in vivo. In this study, we describe a novel technique that uses a recently developed 3D reconstruction technique to calculate shear stress on the endothelium with computational fluid dynamics. In addition, we calculated local wall thickness, the principal plane of curvature, and the location of plaque with reference to this plane, relating these results to shear stress in a human right coronary artery in vivo. Wall thickness and shear stress values for the entire vessel for three inflow-velocity values (10 cm/second, 20 cm/second, and 30 cm/second equivalents with the Reynolds numbers 114, 229, and 457) were as follows: 0.65±0.37 mm (n=1600) and 19.6±1.7 dyne/cm 2 ; 46.1±8.1 dyne/cm 2 and 80.1±16.8 dyne/cm 2 (n=1600). Curvature was 25±9 (m −1 ), resulting in Dean numbers 20±8; 46±16, and 93±33. Selection of data at the inner curvature of the right coronary artery provided wall thickness values of 0.90±0.41 mm (n=100), and shear stress was 17±17, 38±44, and 77±54 dyne/cm 2 (n=100), whereas wall thickness values at the outer curve were 0.37±0.17 mm (n=100) and shear stress values were 22±17, 60±44, and 107±79 dyne/cm 2 (n=100). These findings could be reconciled by an inverse relationship between wall thickness and shear stress for each velocity level under study. For the first time for human vessels in vivo, evidence is presented that low shear stress promotes atherosclerosis. As the method is nondestructive, it allows repeated measurements in the same patient and will provide new insights in the progress of atherosclerosis.