Abstract 10009: Aortic Hemodynamic and Mechanical Properties are Concomitantly Reduced in Pulmonary Arterial Hypertension
Introduction: Although pulmonary arterial hypertension (PAH) has significant impact on flow and tissue remodeling in the pulmonary vasculature, previous studies indicate that PAH is also associated with increased stiffness and endothelial dysfunction in the systemic circulation. Alterations in vascular properties of the systemic circulation may have hemodynamic relevance for left ventricular adaptation to PAH. Reduced wall shear stress (WSS) and vascular elastic markers are known manifestations of vascular disease and may provide insight into the vascular behavior of the systemic circulation in PAH.
Hypothesis: We hypothesized that WSS and mechanical elasticity are altered in the thoracic aorta in PAH, and that these measures correlate with pulmonary hemodynamics.
Methods: As part of a prospective study, 18 patients with PAH and 5 age-matched controls underwent the same day right heart catheterization (RHC) and 4 dimensional flow cardiac magnetic resonance (4D CMR) for computation of WSS in four aortic regions (endovascular landing zones 1 to 4). The aortic capacitance was calculated as the ratio of stroke volume (SV) and pulse pressure (PP). The elastic modulus was defined as the inverse aortic strain divided by PP. The difference in median values was assessed via Wilcoxon ranked sum method and Spearman rho was used for linear regression analysis.
Results: The WSS (N/m2) was significantly reduced in all four aortic zones (zone 1: 0.540 vs. 0.800, p = 0.0325; zone 2: 0.424 vs. 0.615, p = 0.0402; zone 3: 0.419 vs. 0.625, p = 0.0250; zone 4: 0.513 vs. 0.794, p = 0.0046). While aortic capacitance (mL/mmHg) was significantly reduced in the PAH subjects (1.82 vs. 5.97, p = 0.008), the elastic modulus (mmHg) was higher (3.52 vs. 8.25, p = < 0.001). The most significant correlation was between the WSS in zone 4 and pulmonary vascular resistance (rho = -0.70, p = 0.006) and mean pulmonary artery pressure (rho = -0.62, p = 0.002).
Conclusions: PAH is associated with reduced WSS in the thoracic aorta, suggesting reduced systemic flow conduction in PAH. WSS and mechanical vascular markers may aid in the understanding of the impact of PAH on systemic hemodynamics and tissue mechanics.
Author Disclosures: M. Schafer: None. O. Jazaeri: None. V.O. Kheyfets: None. K.S. Hunter: None. R. Shandas: None. K. Buckner: None. B.E. Fenster: None.
- © 2015 by American Heart Association, Inc.