Patient-Specific Computational Analysis of Hemodynamics in Adult Pulmonary Hypertension

Abstract

Pulmonary hypertension (PH) is a progressive disease characterized by elevated pressure and vascular resistance in the pulmonary arteries. Nearly 250,000 hospitalizations occur annually in the US with PH as the primary or secondary condition. A definitive diagnosis of PH requires right heart catheterization (RHC) in addition to a chest computed tomography, a walking test, and others. While RHC is the gold standard for diagnosing PH, it is invasive and posseses inherent risks and contraindications. In this work, we characterized the patient-specific pulmonary hemodynamics in silico for diverse PH WHO groups. We grouped patients on the basis of mean pulmonary arterial pressure (mPAP) into three disease severity groups: at-risk (18mmHg mPAP<25mmHg, denoted with A), mild (25mmHg mPAP<40mmHg, denoted with M), and severe (mPAP ! 40mmHg, denoted with S). The pulsatile flow hemodynamics was simulated by evaluating the three-dimensional Navier-Stokes system of equations using a flow solver developed by customizing OpenFOAM libraries (v5.0, The OpenFOAM Foundation). Quasi patient-specific boundary conditions were implemented using a Womersley inlet velocity profile and transient resistance outflow conditions. Hemodynamic indices such as spatially averaged wall shear stress (SAWSS), wall shear stress gradient (WSSG), timeaveraged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT), were evaluated along with the clinical metrics pulmonary vascular resistance (PVR), stroke volume (SV) and compliance (C), to assess possible spatiotemporal correlations. We observed statistically significant decreases in SAWSS, WSSG, and TAWSS, and increases in OSI and RRT with disease severity. PVR was moderately correlated with SAWSS and RRT at the mid-notch stage of the cardiac cycle when these indices were computed using the global pulmonary arterial geometry. These results are promising in the context of a long-term goal of identifying computational biomarkers that can serve as surrogates for invasive diagnostic protocols of PH.

Subject-specific one-dimensional fluid dynamics model of chronic thromboembolic pulmonary hypertension

“…In the intralobar arteries, TAWSS is higher compared to the extralobar arteries in both baseline and CTEPH conditions. This observation is consistent with Pillalamarri et al ( 2021 ) who found that TAWSS increased with increasing distance from the heart based on a computational investigation of patient-specific pulmonary hemodynamics across 32 subjects in distinct WHO groups of PH. The Pillalamarri et al ( 2021 )study included one subject with CTEPH, in whom TAWSS decreased in the distal part of the network, consistent with our results.…”

Subject-specific one-dimensional fluid dynamics model of chronic thromboembolic pulmonary hypertension

“…This observation is consistent with Pillalamarri et al(2021) who found that TAWSS increased with increasing distance from the heart based on a computational investigation of patient-speci c pulmonary hemodynamics across 32 subjects in distinct WHO groups of PH. The Pillalamarri et al (Pillalamarri et al 2021)study included one subject with CTEPH, in whom TAWSS decreased in the distal part of the network, consistent with our results.…”

Simulating Multi-Scale Pulmonary Vascular Function by Coupling Computational Fluid Dynamics With an Anatomic Network Model

“…differences in time averaged wall shear stress predicted by computational fluid dynamics in patients at risk for or with mild pulmonary hypertension Pillalamarri et al (2021). The redistribution of left-to-right blood flow with posture in the coupled model has implications for prediction of both flow velocity profiles and wall shear stress in computational fluid dynamics models of the major arteries.…”