title: The influence of boundary conditions on wall shear stress distribution in patients specific coronary trees.
abstract: Patient specific geometrical data on human coronary arteries can be reliably obtained multislice computer tomography (MSCT) imaging. MSCT cannot provide hemodynamic variables, and the outflow through the side branches must be estimated. The impact of two different models to determine flow through the side branches on the wall shear stress (WSS) distribution in patient specific geometries is evaluated. Murray's law predicts that the flow ratio through the side branches scales with the ratio of the diameter of the side branches to the third power. The empirical model is based on flow measurements performed by Doriot et al. (2000) in angiographically normal coronary arteries. The fit based on these measurements showed that the flow ratio through the side branches can best be described with a power of 2.27. The experimental data imply that Murray's law underestimates the flow through the side branches. We applied the two models to study the WSS distribution in 6 coronary artery trees. Under steady flow conditions, the average WSS between the side branches differed significantly for the two models: the average WSS was 8% higher for Murray's law and the relative difference ranged from -5% to +27%. These differences scale with the difference in flow rate. Near the bifurcations, the differences in WSS were more pronounced: the size of the low WSS regions was significantly larger when applying the empirical model (13%), ranging from -12% to +68%. Predicting outflow based on Murray's law underestimates the flow through the side branches. Especially near side branches, the regions where atherosclerotic plaques preferentially develop, the differences are significant and application of Murray's law underestimates the size of the low WSS region.
authors.affiliation: Department of Biomedical Engineering, Erasmus Erasmus MC, Biomechanics Laboratory Ee2322, PO Box 2040, 3000 CA Rotterdam, The Netherlands.
authors.forename: Alina G
authors.initials: AG
authors.lastname: van der Giessen
authors.forename: Harald C
authors.initials: HC
authors.lastname: Groen
authors.forename: Pierre-André
authors.initials: PA
authors.lastname: Doriot
authors.forename: Pim J
authors.initials: PJ
authors.lastname: de Feyter
authors.forename: Antonius F W
authors.initials: AF
authors.lastname: van der Steen
authors.forename: Frans N
authors.initials: FN
authors.lastname: van de Vosse
authors.forename: Jolanda J
authors.initials: JJ
authors.lastname: Wentzel
authors.forename: Frank J H
authors.initials: FJ
authors.lastname: Gijsen
mesh_terms: D001783:Blood Flow Velocity; D003331:Coronary Vessels / Q000033:anatomy & histology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008955:Models, Cardiovascular; D013312:Stress, Physiological / Q000502:physiology*