Determination of blood flow and endothelial shear stress in human coronaryartery in vivo

This paper describes a system that permits, for the first time, the in vivo determination of local velocity and endothelial shear stress in the major human coronary arteries. The purpose of the system is to facilitate the stu dy of plaque growth and the relationships between local hemodynamic factors and atherogenesis and restenosis. The three-dimensional anatomy of a segme nt of the right coronary artery was determined immediately after directiona l atherectomy via a combination of intracoronary ultrasound and biplane ang iography. The highly irregular geometry of the segment was then represented in curvilinear coordinates and a computational fluid dynamics technique wa s used to investigate the detailed, intravascular velocity profile and shea r stress distribution. We found minor flow reversals, significant swirling and a large variation of local velocity and shear stress, both axially and circumferentially, within the artery, even in the absence of significant lu minal obstruction. The flow phenomena exhibit characteristics consistent wi th the focal nature of atherogenesis and restenosis. It is concluded that t he technology now exists to determine luminal geometry and local variations in flow fields and endothelial shear stress, in vivo.