EVALUATION OF ENDOTHELIAL SHEAR-STRESS AND 3D GEOMETRY AS FACTORS DETERMINING THE DEVELOPMENT OF ATHEROSCLEROSIS AND REMODELING IN HUMAN CORONARY-ARTERIES IN-VIVO - COMBINING 3D RECONSTRUCTION FROM ANGIOGRAPHYAND IVUS (ANGUS) WITH COMPUTATIONAL FLUID-DYNAMICS

The predilection sites of atherosclerotic plaques implicate theologic factors like shear stress underlying the genesis of atherosclerosis. P resently no technique is available that enables one to provide 3D shea r stress data in human coronary arteries in vivo. In this study, we de scribe a novel technique that uses a recently developed 3D reconstruct ion technique to calculate shear stress on the endothelium with comput ational fluid dynamics. In addition, we calculated local wall thicknes s, the principal plane of curvature, and the location of plaque with r eference to this plane, relating these results to shear stress in a hu man right coronary artery in vivo. Wall thickness and shear stress val ues for the entire vessel for three inflow-velocity values (10 cm/seco nd, 20 cm/second, and 30 cm/second equivalents with the Reynolds numbe rs 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 t he 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/c m(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, an d 107+/-79 dyne/cm(2) (n=100); These findings could be reconciled by a n inverse relationship between wall thickness and shear stress for eac h velocity level under study. For the first time for human vessels in vivo, evidence is presented that low shear stress promotes atheroscler osis. As the method is nondestructive, it allows repeated measurements in the same patient and will provide new insights in the progress of atherosclerosis.