title: Moving domain computational fluid dynamics to interface with an embryonic model of cardiac morphogenesis.
abstract: Peristaltic contraction of the embryonic heart tube produces time- and spatial-varying wall shear stress (WSS) and pressure gradients (∇P) across the atrioventricular (AV) canal. Zebrafish (Danio rerio) are a genetically tractable system to investigate cardiac morphogenesis. The use of Tg(fli1a:EGFP) (y1) transgenic embryos allowed for delineation and two-dimensional reconstruction of the endocardium. This time-varying wall motion was then prescribed in a two-dimensional moving domain computational fluid dynamics (CFD) model, providing new insights into spatial and temporal variations in WSS and ∇P during cardiac development. The CFD simulations were validated with particle image velocimetry (PIV) across the atrioventricular (AV) canal, revealing an increase in both velocities and heart rates, but a decrease in the duration of atrial systole from early to later stages. At 20-30 hours post fertilization (hpf), simulation results revealed bidirectional WSS across the AV canal in the heart tube in response to peristaltic motion of the wall. At 40-50 hpf, the tube structure undergoes cardiac looping, accompanied by a nearly 3-fold increase in WSS magnitude. At 110-120 hpf, distinct AV valve, atrium, ventricle, and bulbus arteriosus form, accompanied by incremental increases in both WSS magnitude and ∇P, but a decrease in bi-directional flow. Laminar flow develops across the AV canal at 20-30 hpf, and persists at 110-120 hpf. Reynolds numbers at the AV canal increase from 0.07±0.03 at 20-30 hpf to 0.23±0.07 at 110-120 hpf (p< 0.05, n=6), whereas Womersley numbers remain relatively unchanged from 0.11 to 0.13. Our moving domain simulations highlights hemodynamic changes in relation to cardiac morphogenesis; thereby, providing a 2-D quantitative approach to complement imaging analysis.
authors.affiliation: Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.
authors.forename: Juhyun
authors.initials: J
authors.lastname: Lee
authors.forename: Mahdi Esmaily
authors.initials: ME
authors.lastname: Moghadam
authors.forename: Ethan
authors.initials: E
authors.lastname: Kung
authors.forename: Hung
authors.initials: H
authors.lastname: Cao
authors.forename: Tyler
authors.initials: T
authors.lastname: Beebe
authors.forename: Yury
authors.initials: Y
authors.lastname: Miller
authors.forename: Beth L
authors.initials: BL
authors.lastname: Roman
authors.forename: Ching-Ling
authors.initials: CL
authors.lastname: Lien
authors.forename: Neil C
authors.initials: NC
authors.lastname: Chi
authors.forename: Alison L
authors.initials: AL
authors.lastname: Marsden
authors.forename: Tzung K
authors.initials: TK
authors.lastname: Hsiai
mesh_terms: D000465:Algorithms; D000818:Animals; D001783:Blood Flow Velocity; D003198:Computer Simulation; D006321:Heart / Q000196:embryology*; D006439:Hemodynamics / Q000502:physiology*; D057446:Hydrodynamics; D008955:Models, Cardiovascular; D009024:Morphogenesis / Q000502:physiology*; D012212:Rheology; D033081:Shear Strength; D015027:Zebrafish