title: Toward translating near-infrared spectroscopy oxygen saturation data for the non-invasive prediction of spatial and temporal hemodynamics during exercise.
abstract: Image-based computational fluid dynamics (CFD) studies conducted at rest have shown that atherosclerotic plaque in the thoracic aorta (TA) correlates with adverse wall shear stress (WSS), but there is a paucity of such data under elevated flow conditions. We developed a pedaling exercise protocol to obtain phase contrast magnetic resonance imaging (PC-MRI) blood flow measurements in the TA and brachiocephalic arteries during three-tiered supine pedaling at 130, 150, and 170 % of resting heart rate (HR), and relate these measurements to non-invasive tissue oxygen saturation [Formula: see text] acquired by near-infrared spectroscopy (NIRS) while conducting the same protocol. Local quantification of WSS indices by CFD revealed low time-averaged WSS on the outer curvature of the ascending aorta and the inner curvature of the descending aorta (dAo) that progressively increased with exercise, but that remained low on the anterior surface of brachiocephalic arteries. High oscillatory WSS observed on the inner curvature of the aorta persisted during exercise as well. Results suggest locally continuous exposure to potentially deleterious indices of WSS despite benefits of exercise. Linear relationships between flow distributions and tissue oxygen extraction calculated from [Formula: see text] were found between the left common carotid versus cerebral tissue [Formula: see text] and the dAo versus leg tissue [Formula: see text]. A resulting six-step procedure is presented to use NIRS data as a surrogate for exercise PC-MRI when setting boundary conditions for future CFD studies of the TA under simulated exercise conditions. Relationships and ensemble-averaged PC-MRI inflow waveforms are provided in an online repository for this purpose.
authors.affiliation: Department of Biomedical Engineering, Marquette University, 1515 West Wisconsin Ave, Milwaukee, WI, 53233, USA. lellwein@vcu.edu.|Department of Mathematics and Applied Mathematics, Virginia Commonwealth University, 1015 Floyd Ave, Richmond, VA, 23284, USA. lellwein@vcu.edu.
authors.forename: Laura
authors.initials: L
authors.lastname: Ellwein
authors.affiliation: Department of Biomedical Engineering, Marquette University, 1515 West Wisconsin Ave, Milwaukee, WI, 53233, USA.|Department of Pediatrics, Herma Heart Center, Children's Hospital of Wisconsin, and the Medical College of Wisconsin, 9000 W Wisconsin Ave, Wauwatosa, WI, 53266, USA.
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Samyn
authors.affiliation: Department of Exercise Science, Marquette University, 604 N. 16th St, Milwaukee, WI, 53233, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Danduran
authors.affiliation: Department of Physical Therapy, Marquette University, 604 N. 16th St, Milwaukee, WI, 53233, USA.
authors.forename: Sheila
authors.initials: S
authors.lastname: Schindler-Ivens
authors.affiliation: Department of Radiology, Children's Hospital of Wisconsin, 9000 W Wisconsin Ave, Wauwatosa, WI, 53266, USA.
authors.forename: Stacy
authors.initials: S
authors.lastname: Liebham
authors.affiliation: Department of Biomedical Engineering, Marquette University, 1515 West Wisconsin Ave, Milwaukee, WI, 53233, USA.|Division of Cardiovascular Medicine, Departments of Medicine and Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA.
authors.forename: John F
authors.initials: JF
authors.lastname: LaDisa
mesh_terms: D001783:Blood Flow Velocity; D015444:Exercise / Q000502:physiology*; D006439:Hemodynamics; D006801:Humans; D057446:Hydrodynamics; D008955:Models, Cardiovascular; D010100:Oxygen / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared
chemical_list: D010100:Oxygen