title: Impact of bifurcation angle and other anatomical characteristics on blood flow - A computational study of non-stented and stented coronary arteries.
abstract: The hemodynamic influence of vessel shape such as bifurcation angle is not fully understood with clinical and quantitative observations being equivocal. The aim of this study is to use computational modeling to study the hemodynamic effect of shape characteristics, in particular bifurcation angle (BA), for non-stented and stented coronary arteries. Nine bifurcations with angles of 40°, 60° and 80°, representative of ±1 SD of 101 asymptomatic computed tomography angiogram cases (average age 54±8 years; 57 females), were generated for (1) a non-stented idealized, (2) stented idealized, and (3) non-stented patient-specific geometry. Only the bifurcation angle was changed while the geometries were constant to eliminate flow effects induced by other vessel shape characteristics. The commercially available Biomatrix stent was used as a template and virtually inserted into each branch, simulating the T-stenting technique. Three patient-specific geometries with additional shape variation and ±2 SD BA variation (33°, 42° and 117°) were also computed. Computational fluid dynamics (CFD) analysis was performed for all 12 geometries to simulate physiological conditions, enabling the quantification of the hemodynamic stress distributions, including a threshold analysis of adversely low and high wall shear stress (WSS), low time-averaged WSS (TAWSS), high spatial WSS gradient (WSSG) and high Oscillatory Shear Index (OSI) area. The bifurcation angle had a minor impact on the areas of adverse hemodynamics in the idealized non-stented geometries, which fully disappeared once stented and was not apparent for patient geometries. High WSS regions were located close to the carina around peak-flow, and WSSG increased significantly after stenting for the idealized bifurcations. Additional shape variations affected the hemodynamic profiles, suggesting that BA alone has little effect on a patient׳s hemodynamic profile. Incoming flow angle, diameter and tortuosity appear to have stronger effects. This suggests that other bifurcation shape characteristics and stent placement/strategy may be more important than bifurcation angle in atherosclerotic disease development, progression, and stent outcome.
authors.affiliation: Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: s.beier@auckland.ac.nz.
authors.forename: Susann
authors.initials: S
authors.lastname: Beier
authors.affiliation: Mercy Angiography, 98 Mountain Rd, Mt Eden, 1023, Auckland, New Zealand. Electronic address: Johno@mercyangiography.co.nz.
authors.forename: John
authors.initials: J
authors.lastname: Ormiston
authors.affiliation: Green Lane Cardiovascular Service, Auckland City Hospital, Park Rd, Auckland 1030, New Zealand. Electronic address: MWebster@adhb.govt.nz.
authors.forename: Mark
authors.initials: M
authors.lastname: Webster
authors.affiliation: Faculty of Engineering, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: j.cater@auckland.ac.nz.
authors.forename: John
authors.initials: J
authors.lastname: Cater
authors.affiliation: Faculty of Engineering, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: s.norris@auckland.ac.nz.
authors.forename: Stuart
authors.initials: S
authors.lastname: Norris
authors.affiliation: Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: p.medrano@auckland.ac.nz.
authors.forename: Pau
authors.initials: P
authors.lastname: Medrano-Gracia
authors.affiliation: Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: a.young@auckland.ac.nz.
authors.forename: Alistair
authors.initials: A
authors.lastname: Young
authors.affiliation: Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand. Electronic address: b.cowan@auckland.ac.nz.
authors.forename: Brett
authors.initials: B
authors.lastname: Cowan
mesh_terms: D003198:Computer Simulation; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000033:anatomy & histology* / Q000502:physiology*; D005260:Female; D006439:Hemodynamics; D006801:Humans; D057446:Hydrodynamics; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D015607:Stents; D013314:Stress, Mechanical
keywords: Bifurcation angle; Computational fluid dynamics (CFD); Coronary artery disease; Hemodynamics; Stent