Unveiling the hidden local hemodynamics of peripheral circulation: integration of computational fluid dynamics and diastolic pressure decay

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Abstract Background Peripheral arterial hemodynamics are altered by cardiovascular risk factors. While obvious abnormalities may be detected via conventional flow and pressure measurements, these parameters may overlook the subtle changes of preclinical disease progression. Computational Fluid Dynamics (CFD) incorporates the interaction between three-dimensional anatomy and local hemodynamics with high temporospatial resolution, via wall shear stress (WSS) derived parameters —time-averaged WSS (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and endothelial cell activation potential (ECAP)— that reflect flow direction and intensity of flow along with endothelial functionality. Additionally, the diastolic rate constant (DRC) derived from the pressure waveform, serves as a measure of peripheral vasotonus, beyond standard arterial blood pressure (ABP) parameters. Purpose We aimed to investigate whether the integration of DRC into CFD analysis, using individualized gender-specific models, could reveal subtle differences concealed by traditional blood pressure parameters in a given, mutual 3D-anatomy of hand vasculature. Method Simultaneous radial artery flow and peripheral non-invasive arterial pressure recordings were acquired from 16 non-diabetic patients for analysis. Mean arterial pressure signal (MAP) window (>8 cycle) were used for DRC calculation. A CFD model was developed to analyze radial and ulnar artery hemodynamics, using an idealized geometry with two inlets and five outlets. Pre-analyses on a simplified brachial artery bifurcation model, using a literature-based inlet velocity and Murray's law for outflow split, determined the radial and ulnar artery flow distribution. To estimate the unknown ulnar artery velocity profile, gender-specific models, accounting for anatomical differences, were created, ultimately generating individualized ulnar velocity profiles for each patient (Fig. 1). Results Higher DRC values, suggesting attenuated peripheral vasotonus, are strongly correlated with higher OSImean (r: 0.652, p: 0.006), RRTmean (r: 0.630, p: 0.009) and ECAPmean (r: 0.664, p: 0.005), independent of MAP. Notably, no correlation was found between WSS-derived parameters and MAP, systolic blood pressure (SBP) or diastolic blood pressure (DBP)(p>0.05 for all). Even with comparable conventional ABP, a combined model with CFD and DRC revealed subtle changes in local hemodynamics (Fig. 2). Conclusion For the same arterial anatomy and similar MAP, SBP and DBP, a steeper diastolic pressure decay correlates elevated OSI and RRT indicative of undesirable local flow perturbations, potentially harmful for vasculature. Integrating patient-specific anatomy via CFD and pressure waveform morphology via DRC into hemodynamic assessment may enhance the evaluation of peripheral circulation, revealing subtle alterations conceladed by traditional hemodynamics, paving the way of personalized evaluation of vascular disease.Methodology & key findings Two example cases

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