Abstract 18862: Wall Shear Stress in Pulmonary Hypertension

Abstract

Pulmonary arterial hypertension (PAH) leads to morphometric remodeling of the pulmonary arteries. Computational fluid dynamics (CFD) modeling has the potential to reveal continuum metrics associated with the stress acting on the vascular endothelium in a non- invasive manner. We hypothesized that the PA endothelium of PAH patients will be subject to abnormal wall shear stress (WSS), and thus investigated the relationship of spatially averaged WSS (SAWSS) with invasive measurements of pulmonary vascular resistance (PVR) and compliance (C). Methods: Computed tomography angiography (CTA) and RHC were used to acquire images and hemodynamic data in 19 PH patients. Each patient’s pulmonary vascular tree was reconstructed from CT images up to 6 generations. The inlets and outlets were extended to 10 times their hydraulic diameters and a volumetric mesh created within element dimensions determined by a systematic mesh convergence study. Each CFD model was simulated using a structured tree outflow boundary condition. Constant flow rate simulations were performed using the numerical solver Fluent (ANSYS Inc., Lebanon, NH) after adjusting for patient-specific scaling parameters. Finally, SAWSS on the surface of the pulmonary arterial endothelium was obtained during post-processing. Correlations between SAWSS and hemodynamics were made. Results: Figure 1 shows a power-regression correlation between SAWSS and PVR, and linear-regression correlation between SAWSS and C. SAWSS decreases for increasing PVR and decreasing C. Conclusions: Pulmonary arterial WSS obtained by our CFD model can be used as a physiologically relevant quantitative metric of PAH severity, which likely precedes vascular and ventricular remodeling. Its application as a non-invasive surrogate for disease progression and evaluation of response to PH specific therapies needs further investigation.