title: Heterogeneous mechanics of the mouse pulmonary arterial network.
abstract: Individualized modeling and simulation of blood flow mechanics find applications in both animal research and patient care. Individual animal or patient models for blood vessel mechanics are based on combining measured vascular geometry with a fluid structure model coupling formulations describing dynamics of the fluid and mechanics of the wall. For example, one-dimensional fluid flow modeling requires a constitutive law relating vessel cross-sectional deformation to pressure in the lumen. To investigate means of identifying appropriate constitutive relationships, an automated segmentation algorithm was applied to micro-computerized tomography images from a mouse lung obtained at four different static pressures to identify the static pressure-radius relationship for four generations of vessels in the pulmonary arterial network. A shape-fitting function was parameterized for each vessel in the network to characterize the nonlinear and heterogeneous nature of vessel distensibility in the pulmonary arteries. These data on morphometric and mechanical properties were used to simulate pressure and flow velocity propagation in the network using one-dimensional representations of fluid and vessel wall mechanics. Moreover, wave intensity analysis was used to study effects of wall mechanics on generation and propagation of pressure wave reflections. Simulations were conducted to investigate the role of linear versus nonlinear formulations of wall elasticity and homogeneous versus heterogeneous treatments of vessel wall properties. Accounting for heterogeneity, by parameterizing the pressure/distention equation of state individually for each vessel segment, was found to have little effect on the predicted pressure profiles and wave propagation compared to a homogeneous parameterization based on average behavior. However, substantially different results were obtained using a linear elastic thin-shell model than were obtained using a nonlinear model that has a more physiologically realistic pressure versus radius relationship.
authors.affiliation: Department of Molecular and Integrative Physiology, University of Michigan, 2800 Plymouth Road, North Campus Research Center, Ann Arbor, MI, 48109-5622, USA.
authors.forename: Pilhwa
authors.initials: P
authors.lastname: Lee
authors.affiliation: Department of Molecular and Integrative Physiology, University of Michigan, 2800 Plymouth Road, North Campus Research Center, Ann Arbor, MI, 48109-5622, USA.
authors.forename: Brian E
authors.initials: BE
authors.lastname: Carlson
authors.affiliation: Department of Biomedical Engineering, University of Wisconsin-Madison, 2146 ECB; 1550 Engineering Drive, Madison, WI, 53706-1609, USA.
authors.forename: Naomi
authors.initials: N
authors.lastname: Chesler
authors.affiliation: Department of Mathematics, North Carolina State University, Campus Box 8205, Raleigh, NC, 27502, USA.
authors.forename: Mette S
authors.initials: MS
authors.lastname: Olufsen
authors.affiliation: Department of Mathematics, North Carolina State University, Campus Box 8205, Raleigh, NC, 27502, USA.
authors.forename: M Umar
authors.initials: MU
authors.lastname: Qureshi
authors.affiliation: Imaging Sciences and Biomedical Engineering Division, St Thomas' Hospital, King's College London, London, SE1 7EH, UK.|Faculty of Engineering, 20 Symonds St, Auckland, 1010, New Zealand.
authors.forename: Nicolas P
authors.initials: NP
authors.lastname: Smith
authors.affiliation: Imaging Sciences and Biomedical Engineering Division, St Thomas' Hospital, King's College London, London, SE1 7EH, UK.
authors.forename: Taha
authors.initials: T
authors.lastname: Sochi
authors.affiliation: Department of Molecular and Integrative Physiology, University of Michigan, 2800 Plymouth Road, North Campus Research Center, Ann Arbor, MI, 48109-5622, USA. beardda@med.umich.edu.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Beard
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001783:Blood Flow Velocity / Q000502:physiology; D051379:Mice; D017711:Nonlinear Dynamics; D009716:Numerical Analysis, Computer-Assisted; D011312:Pressure; D011651:Pulmonary Artery / Q000502:physiology*; D015203:Reproducibility of Results; D013314:Stress, Mechanical
keywords: Arterial blood flow; Heterogeneity; Pressure–radius relationship; Pulmonary arterial network; Vessel mechanics; Wave intensity analysis