title: Main pulmonary arterial wall shear stress correlates with invasive hemodynamics and stiffness in pulmonary hypertension.
abstract: Pulmonary hypertension (PH) is associated with proximal pulmonary arterial remodeling characterized by increased vessel diameter, wall thickening, and stiffness. In vivo assessment of wall shear stress (WSS) may provide insights into the relationships between pulmonary hemodynamics and vascular remodeling. We investigated the relationship between main pulmonary artery (MPA) WSS and pulmonary hemodynamics as well as markers of stiffness. As part of a prospective study, 17 PH patients and 5 controls underwent same-day four-dimensional flow cardiac magnetic resonance imaging (4-D CMR) and right heart catheterization. Streamwise velocity profiles were generated in the cross-sectional MPA in 45° increments from velocity vector fields determined by 4-D CMR. WSS was calculated as the product of hematocrit-dependent viscosity and shear rate generated from the spatial gradient of the velocity profiles. In-plane average MPA WSS was significantly decreased in the PH cohort compared with that in controls (0.18 ± 0.07 vs. 0.32 ± 0.08 N/m(2); P = 0.01). In-plane MPA WSS showed strong inverse correlations with multiple hemodynamic indices, including pulmonary resistance (ρ = -0.74, P < 0.001), mean pulmonary pressure (ρ = -0.64, P = 0.006), and elastance (ρ = -0.70, P < 0.001). In addition, MPA WSS had significant associations with markers of stiffness, including capacitance (ρ = 0.67, P < 0.001), distensibility (ρ = 0.52, P = 0.013), and elastic modulus (ρ = -0.54, P = 0.01). In conclusion, MPA WSS is decreased in PH and is significantly associated with invasive hemodynamic indices and markers of stiffness. 4-D CMR-based assessment of WSS may represent a novel methodology to study blood-vessel wall interactions in PH.
authors.affiliation: Division of Cardiology, National Jewish Health, Denver, Colorado, USA; Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA.
authors.forename: Michal
authors.initials: M
authors.lastname: Schäfer
authors.affiliation: Division of Cardiology, National Jewish Health, Denver, Colorado, USA; Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA.
authors.forename: Vitaly O
authors.initials: VO
authors.lastname: Kheyfets
authors.affiliation: Division of Radiology, National Jewish Health, Denver, Colorado, USA.
authors.forename: Joyce D
authors.initials: JD
authors.lastname: Schroeder
authors.affiliation: Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA.
authors.forename: Jamie
authors.initials: J
authors.lastname: Dunning
authors.affiliation: Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA.
authors.forename: Robin
authors.initials: R
authors.lastname: Shandas
authors.affiliation: Division of Cardiology, National Jewish Health, Denver, Colorado, USA.
authors.forename: J Kern
authors.initials: JK
authors.lastname: Buckner
authors.affiliation: Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado, USA.
authors.forename: James
authors.initials: J
authors.lastname: Browning
authors.affiliation: Department of Mechanical Engineering, University of Colorado Boulder, Boulder, Colorado, USA.
authors.forename: Jean
authors.initials: J
authors.lastname: Hertzberg
authors.affiliation: Department of Bioengineering, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado, USA; BEF and KSH are co-senior authors.
authors.forename: Kendall S
authors.initials: KS
authors.lastname: Hunter
authors.affiliation: Division of Cardiology, National Jewish Health, Denver, Colorado, USA; BEF and KSH are co-senior authors.
authors.forename: Brett E
authors.initials: BE
authors.lastname: Fenster
keywords: 4-D cardiac magnetic resonance imaging; pulmonary hypertension; wall shear stress