Inlet and outlet boundary conditions (BCs) play an important role in newly emerged image-based computational hemodynamics for blood flows in human arteries anatomically extracted from medical images. We developed physiological inlet and outlet BCs based on patients’ medical data and integrated them into the volumetric lattice Boltzmann method. The inlet BC is a pulsatile paraboloidal velocity profile, which fits the real arterial shape, constructed from the Doppler velocity waveform. The BC of each outlet is a pulsatile pressure calculated from the three-element Windkessel model, in which three physiological parameters are tuned by the corresponding Doppler velocity waveform. Both velocity and pressure BCs are introduced into the lattice Boltzmann equations through Guo’s non-equilibrium extrapolation scheme. Meanwhile, we performed uncertainty quantification for the impact of uncertainties on the computation results. An application study was conducted for six human aortorenal arterial systems. The computed pressure waveforms have good agreement with the medical measurement data. A systematic uncertainty quantification analysis demonstrates the reliability of the computed pressure with associated uncertainties in the Windkessel model. With the developed physiological BCs, the image-based computation hemodynamics is expected to provide a computation potential for the noninvasive evaluation of hemodynamic abnormalities in diseased human vessels.

Vascular disease is the leading cause of morbidity and mortality and a major cause of disability for Americans, and arterial stenosis is its most common form in systemic arteries. Hemodynamic characterization in a stenosed arterial system plays a crucial role in the diagnosis of its lesion severity and the decision-making process for revascularization, but it is not readily available in the current clinical measurements. The newly emerged image-based computational hemodynamics (ICHD) technique provides great potential to characterize the hemodynamics with fine temporospatial resolutions in realistic human vessels, but medical data is rather limited for validation requirements. We present an image-based experimental hemodynamics (IEHD) technique through a mock circulation loop (MCL) to bridge this critical gap. The MCL mimics blood circulation in human stenosed systemic arterial systems that can be either 3D-printed silicone, artificial, or cadaver arteries and thus enables in vitro measurement of hemodynamics. In this work, we focus on the development and validation of the MCL for the in vitro measurement of blood pressure in stenosed silicone arteries anatomically extracted from medical imaging data. Five renal and six iliac patient cases are studied. The pressure data from IEHD were compared with those from ICHD and medical measurement. The good agreements demonstrate the reliability of IEHD. We also conducted two parametric studies to demonstrate the medical applicability of IEHD. One was the cardiovascular response to MCL parameters. We found that blood pressure has a linear correlation with stroke volume and heart rate. Another was the effect of arterial stenosis, characterized by the volumetric reduction (VR) of the arterial lumen, on the trans-stenotic pressure gradient (TSPG). We parametrically varied the stenosis degree and measured the corresponding TSPG. The TSPG-VR curve provides a critical VR that can be used to assess the true hemodynamic severity of the stenosis. Meanwhile, the TSPG at VR = 0 can predict the potential pressure improvement after revascularization. Unlike the majority of existing MCLs that are mainly used to test medical devices involving heart function, this MCL is unique in its specific focus on pressure measurement in stenosed human systemic arteries. Meanwhile, rigorous hemodynamic characterization through concurrent IEHD and ICHD will significantly enhance our current understanding of the pathophysiology of stenosis and contribute to advancements in the medical treatment of arterial stenosis.

Background: Healthcare workers' (HCWs') acceptance of the coronavirus disease 2019 (COVID-19) vaccines constitutes a globally concerned issue, which exhibits variations across different countries and distinct phases of the pandemic. Specifically, the characteristics of HCWs' vaccine acceptance in China following the pre- and post-pandemic period in 2023 remain unclear. Methods: We conducted a population-based two-phase cross-sectional study in Zhejiang, China. Phase 1 was implemented during the pre-pandemic period (July–September 2022), with the primary objective of investigating HCWs' willingness to receive the fourth dose of COVID-19 vaccine. Phase 2, conducted in the post-pandemic period (November 2023–January 2024), focused on exploring HCWs' willingness to undergo annual COVID-19 vaccination. A total of 1,657 HCWs participated in the survey, where data on demographic characteristics, vaccination history, risk perception, and behavioral factors were collected. Multivariate logistic regression analysis was subsequently performed to identify factors associated with HCWs' vaccination willingness. Results: In the first phase (2022, n = 820), 70.61% of participants expressed willingness to receive the fourth dose of the COVID-19 vaccine. Separately, in the second phase (2023, n = 837), the willingness of HCWs to undergo annual COVID-19 vaccination was 28.43%. Concurrently, a substantial decline in HCWs' trust in vaccines was observed: 85.24% of respondents endorsed vaccine safety in 2022, whereas this proportion fell to 57.23% in 2023. Similar downward trends were noted in perceived efficacy (from 78.78% in 2022 to 53.41% in 2023) and vaccine recommendation rates (from 86.10% in 2022 to 56.27% in 2023). Women were less likely to accept a fourth dose [odds ratio (OR) = 0.56, 95% confidence interval (CI): 0.37–0.85]. Laboratory personnel (OR = 3.57, 95% CI: 1.22–10.45) and those confident in vaccine efficacy (OR = 5.06, 95% CI: 1.95–13.08) were more likely to receive a booster. Prior vaccination plus high trust strongly predicted willingness for annual vaccination adherence (OR = 7.23, 95% CI: 4.05–12.92). Despite high primary-series (99.3%) and booster (92.8%) coverage, 7.2% remained unboosted; 33.3% cited lack of awareness and 50% reported contraindications. Conclusion: Following the COVID-19 pandemic, notable shifts were observed in HCWs regarding their perceptions, acceptance, and recommendation behaviors toward COVID-19 vaccines. Collectively, the observations presented herein provide empirical evidence to inform the optimization of COVID-19 vaccination strategies targeting HCWs.