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Flow of cerebrospinal fluid through perivascular pathways in and around the brain may play a crucial role in brain metabolite clearance. While the driving forces of such flows remain enigmatic, experiments have shown that pulsatility is central. In this work, we present a novel network model for simulating pulsatile fluid flow in perivascular networks, taking the form of a system of Stokes-Brinkman equations posed over a perivascular graph. We apply this model to study physiological questions concerning the mechanisms governing perivascular fluid flow in branching vascular networks. Notably, our findings reveal that even long wavelength arterial pulsations can induce directional flow in asymmetric, branching perivascular networks. In addition, we establish fundamental mathematical and numerical properties of these Stokes-Brinkman network models, with particular attention to increasing graph order and complexity. By introducing weighted norms, we show the well-posedness and stability of primal and dual variational formulations of these equations, and that of mixed finite element discretizations., (© 2024. The Author(s).)

Although the hemodynamics of cerebral aneurysms have been extensively studied using patient-specific computational fluid dynamics techniques, no specific hemodynamic factors characteristic of cerebral aneurysm development have yet been identified. We believe that one problem with previous hemodynamic studies of cerebral aneurysms has been the manner in which control groups were created for comparison with experimental groups. The purpose of this study was to determine hemodynamic factors that correlated with the development of cerebral aneurysms. The control group was established in a manner that differed from those of previous works. This allowed us to demonstrate the effectiveness of our method. We artificially removed aneurysms in the middle cerebral artery bifurcations of nine patients and reconstructed the vessel geometries before the aneurysms had occurred. Pulsatile blood flow simulations were performed using the vessel geometries ipsilateral and contralateral to the sites of aneurysm removal, and hemodynamic metrics were calculated. Use of the ipsilateral and contralateral sides as the experimental and control sites, respectively, allowed us to evaluate statistically the hemodynamic metrics between the two corresponding sites/groups. The results showed that only the normalized transverse wall shear stress (NtransWSS) was significantly higher at the MCA bifurcation ipsilateral to the site of aneurysm removal than at the contralateral bifurcation (p = 0.01). There were no significant differences in the other hemodynamic metrics between the bilateral bifurcations. Our findings imply that multi-directional disturbed wall shear stress, which is detected by the NtransWSS metric, may be one hemodynamic risk factor for the development of cerebral aneurysms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Purpose: Non-contrast-enhanced time of flight (TOF) is a standard method for magnetic resonance angiography used to depict vessel morphology. TOF is commonly performed with a 3D steady-state acquisition, employing a short repetition time to support high resolution imaging. At 7 T, TOF exhibits substantial increase in SNR and contrast, improving its clinical value. However, one of the remaining challenges, exacerbated at 7 T, is the presence of artifacts due to pulsatile blood flow, especially near major blood vessels. In this study we examine a method to significantly reduce these artifacts., Methods: We recently introduced a new "local-scrambling" approach that semi-randomizes the acquisition order of the phase encodes, to achieve a controllable cutoff frequency above which the artifacts are drastically reduced. With this approach, artifacts resulting from fast local fluctuations such as cardiac pulsation are significantly reduced. In this study, we explore the ability of this local-scrambling approach to reduce pulsatile blood flow artifacts in a 3D TOF acquisition. Cartesian line-by-line and center-out ordering, with and without local-scrambling, were compared in simulations and in human brain imaging at 3 and 7 T scanners., Results: In the simulations the artifact intensity showed a 10-fold reduction using local-scrambling compared to line-by-line and 4-fold compared to center-out ordering. In vivo results show that artifacts are much more pronounced at 7 T compared to 3 T, and in both cases they are effectively reduced by local-scrambling., Conclusion: Local-scrambling improves image quality for both line-by-line and center-out ordering. This approach can easily be implemented in the scanner without any changes to the reconstruction., (© 2024 The Author(s). Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Objective: Pulse-synchronous tinnitus (PST) has been linked to multiple anatomical variants of the central venous outflow tract (CVOT) including sigmoid sinus (SS) dehiscence and diverticulum. This study investigates flow turbulence, pressure, and wall shear stress along the CVOT and proposes a mechanism that results in SS dehiscence and PST., Study Design: Case series., Setting: Tertiary Academic Center., Methods: Venous models were reconstructed from computed tomography scans of 3 patients with unilateral PST. Two models for each patient are obtained: a symptomatic and contralateral asymptomatic side. A turbulent model-enabled commercial flow solver was used to simulate the pulsatile blood flow over the cardiac cycle through the models. Fluid flow through the transverse and SS junction was analyzed to observe the velocity, pressure, turbulent kinetic energy (TKE), and shear stress over a simulated cardiac cycle., Results: Fluid flow on the symptomatic side showed increased vorticity in the presence of an SS diverticulum. Higher TKE with periodicity following the cardiac cycle was observed on the symptomatic side, and a sharp increase was observed if SS diverticulum was present. Shear stress was highest near the narrowest segments of the vessel. Pressure was observed to be lower on the symptomatic side at the transverse-SS junction for all 3 patients., Conclusion: Computational fluid dynamics modeling of blood flow through the CVOT in PST suggests that low pressure may be the cause of dehiscence, and tinnitus may result from periodic increases in TKE., (© 2024 American Academy of Otolaryngology–Head and Neck Surgery Foundation.)

Background: According to the most recent pulmonary hypertension (PH) guidelines, a main pulmonary artery (MPA) diameter > 25 mm on transthoracic echocardiography supports the diagnosis of PH. However, the size of the pulmonary artery (PA) may vary according to body size, age, and cardiac phases., Research Question: (1) What are the reference limits for PA size on transthoracic echocardiography, considering differences in body size, sex, and age? (2) What is the diagnostic value of the PA size for classifying PH? (3) How does the selection of different reference groups (healthy volunteers vs patients referred for right heart catheterization [RHC]) influence the diagnostic OR (DOR)?, Study Design and Methods: The study included a reference cohort of 248 healthy individuals as control patients, 693 patients with PH proven by RHC, and 156 patients without PH proven by RHC. In the PH cohort, 300 had group 1 PH, 207 had group 2 PH, and 186 had group 3 PH. MPA and right PA diameters and areas were measured in the upper sternal short-axis and suprasternal notch views. Reference limits (5th-95th percentile) were based on absolute values and height-indexed measures. Quantile regression analysis was used to derive median and 95th quantile reference equations for the PA measures. DORs and probability diagnostic plots for PH were then determined using healthy control and non-PH cohorts., Results: The 95th percentile for indexed MPA diameter was 15 mm/m in diastole and 19 mm/m in systole in both sexes. Quantile regression analysis revealed a weak age effect (pseudo-R 2 of 0.08-0.10 for MPA diameters). Among measures, the MPA size in diastole had the highest DOR (156.2; 95% CI, 68.3-357.5) for detection of group 1 PH. Similarly, the DORs were also high for groups 2 and 3 PH when compared with the control cohort but significantly lower compared with the non-PH cohort., Interpretation: This study presents novel reference limits for MPA based on height indexing and quantile regression., Competing Interests: Financial/Nonfinancial Disclosures The authors have reported to CHEST the following: F. H. received funding from Janssen Inc to conduct the research. None declared (S. P. B., B. E. C., E. J. S., M. S., K. C. N., A. J. S., R. T. Z.)., (Published by Elsevier Inc.)

In bivalves and gastropods, ventricle contraction causes a negative pressure in the auricles and increases venous return from the afferent oblique vein (AOV): the constant-volume (CV) mechanism. The flow in the AOV should be a pulsative flow synchronized with the ventricular contraction. The flow in the heart and adjacent vessels of Mytilus galloprovincialis were measured by magnetic resonance imaging to confirm this hypothesis. Under a regular heartbeat, pulsative flows in the AOV and branchial vessels (BVs) were almost completely synchronized with the flow in the aorta, while filling of the ventricle was in the opposite phase. Flows in the BVs were directed to the posterior direction, and a pair of BVs in the gill axes (the efferent BVs) were connected to the AOV. Based on the images of the whole pathway of the AOV in an oblique slice, we confirmed that haemolymph flow was evoked from the efferent BVs and flow into the ventricle via the auricle was completed in a single heartbeat. Therefore, the walls of the AOV and BVs could resist negative transmural pressure caused by the ventricular contraction. In conclusion, the auricle, the AOV and the BVs, including the gill filaments, act as a suction pump. The pulsative venous return is driven by the negative pressure of the AOV as in the CV mechanism, and the negative pressure in the efferent BVs could draw haemolymph from the sinus via the gill and the afferent BVs. Therefore, Mytilus can start and stop its heartbeat as necessary., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Background: Routine Doppler study is a common tool for early diagnosis of Fetal Growth Restriction (FGR) and Small for Gestational Age (SGA) patients. It aimed to determine the role of the Foramen Ovale Pulsatility Index (FOPI) study beside routine Doppler study among patients with FGR and SGA fetuses., Methods: This prospective study was conducted on 35 FGR, 32 SGA, and 33 Appropriate for Gestational Age (AGA) fetuses. Demographic data, amniotic fluid index, neonatal outcome, and Doppler velocimetry, including Umbilical Artery Pulsatility Index (UMAPI), Uterine Artery Pulsatility Index (UTAPI), Middle Cerebral Artery Pulsatility Index (MCAPI), Ductus Venosus Pulsatility Index (DVPI), and FOPI were documented. Kolmogorov-Smirnov normality test, one-way ANOVA, Mann-Whitney U, Kruskal-Wallis, non-parametric pairwise comparisons adjusted for Bonferroni correction, Pearson correlation test, Chi square, Fisher's exact test, and Receiver Operating Characteristic Curve (ROC) analysis with Youden's Index (sensitivity+specificity-1) to estimate cut-off point were used to analyze the data at significance level <0.05 for all tests., Results: FOPI cut-off points were 2.24 (sensitivity=77%, specificity=94%) and 1.15 (sensitivity=90%, specificity=20%) to predict FGR and SGA, respectively. FOPI showed a positive correlation with UMAPI and UTAPI (r=0.52 and r=0.30, P<0.001 and P=0.006, respectively), but not with MCAPI and DVPI (r=0.08 and r=0.12, P=0.50 and P=0.30, respectively). Besides, UMAPI, UTAPI, and FOPI were altered among patients with stages I and II FGR. Umbilical cord potential hydrogen (umbilical cord pH), 1- and 5-min Apgar score significantly increased by Birth weight centile; however, UMAPI, FOPI, and UTAPI significantly decreased., Conclusion: UMAPI is recommended to predict short-term neonatal morbidities and demonstrate the early or late onset FGR. Besides, FOPI is suggested as the first-line Doppler study to detect abnormal growth velocity. More studies are warranted, especially considering long-term neonatal morbidities., Competing Interests: None declared., (Copyright: © Iranian Journal of Medical Sciences.)

Purpose: We aimed to evaluate several quantitative methods to describe the diastolic notch (DN) and compare their performance in the prediction of fetal growth restriction., Materials and Methods: Patients who underwent a placental scan at 16-26 weeks of gestation and delivered between Jan 2016 and Dec 2020 were included. The uterine artery pulsatility index was measured for all of the patients. In patients with a DN, it was quantified using the notch index and notch depth index. Odds ratios for small for gestational age neonates (defined as birth weight <10th and <5th percentile) were calculated. Predictive values of uterine artery pulsatility, notch, and notch depth index for fetal growth restriction were calculated., Results: Overall, 514 patients were included, with 69 (13.4%) of them delivering a small for gestational age neonate (birth weight<10th percentile). Of these, 20 (20.9%) had a mean uterine artery pulsatility index >95th percentile, 13 (18.8%) had a unilateral notch, and 11 (15.9%) had a bilateral notch. 16 patients (23.2%) had both a high uterine artery pulsatility index (>95th percentile) and a diastolic notch. Comparison of the performance between uterine artery pulsatility, notch, and notch depth index using receiver operating characteristic curves to predict fetal growth restriction <10th percentile found area under the curve values of 0.659, 0.679, and 0.704, respectively, with overlapping confidence intervals., Conclusion: Quantifying the diastolic notch at 16-26 weeks of gestation did not provide any added benefit in terms of prediction of neonatal birth weight below the 10th or 5th percentile for gestational age, compared with uterine artery pulsatility index., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

The physiologic impact of pulsatile flow (PF) on end-organ perfusion during cardiopulmonary bypass (CPB) is controversial. Using an intra-aortic balloon pump (IABP) to maintain PF during CPB for patients undergoing heart transplantation (HT) may impact end-organ perfusion, with implications for postoperative outcomes. A single-center retrospective study of 76 patients bridged to HT with IABP was conducted between January 2018 and December 2022. Beginning in May 2022, patients received IABP-generated PF during CPB at an internal rate of 80 beats/minute. Fifty-eight patients underwent HT with the IABP turned off (IABP-Off), whereas 18 patients underwent HT with IABP-generated PF (IABP-On). The unmatched IABP-On group experienced shorter organ ischemia times (180 vs . 203 minutes, p = 0.015) and CPB times (104 vs . 116 minutes, p = 0.022). The cohort was propensity matched according to age, organ ischemia time, and CPB time. Elevations in postoperative lactates in the immediate (2.8 vs . 1.5, p = 0.062) and 24 hour (4.7 vs . 2.4, p = 0.084) postoperative periods trended toward significance in the matched IABP-Off group. There was no difference in postoperative vasoactive inotropic score (VIS), postoperative creatinine, or length of stay. This limited preliminary data suggest that maintaining counterpulsation to generate PF during CPB may improve end-organ perfusion in this patient population as suggested by lower postoperative lactate levels., Competing Interests: Disclosure: The authors have no conflicts of interest to report., (Copyright © ASAIO 2024.)

Hemodynamic analysis reveals a highly significant effect on the prevention, diagnosis, and treatment of human vascular diseases. This article goes deeply into the periodic pulsatile blood flow in the carotid artery with an elastic vessel wall. In view of blood rheological experimental data, the constitutive equation of fractional Maxwell power-law fluid with yield stress, which can describe the four characteristics of yield stress, viscoelasticity, shear thinning, and thixotropy is established. Meanwhile, drawing support from the data of pulsatile flow, the finite Fourier series of pressure gradient with a period of 1 s has been proposed. Leading into Hooke's law can build the fluid-structure coupling boundary condition of blood flow and elastic vessel wall. The numerical solutions are got hold of finite difference method integrated with the newly developed L1-algorithm, and their convergence and stability of which are verified. The axial velocities of blood under different constitutive relationships are compared. The results throw light that other constitutive relationships underestimate the velocity of blood. Furthermore, the flow rate and wall shear stress on different fluid are calculated. It can be concluded that compared with Bingham fluid, the maximum and minimum flow rate/wall shear stress of fractional Maxwell power-law fluid with yield stress increases by 19% and 32%, respectively. The flow rate lags behind the pressure gradient and has time delay effect, on the contrary, the velocity of blood vessel wall is keeping pace with the pressure gradient. The effects of relevant physical parameters on velocity are discussed. In addition, the spatiotemporal distribution of blood flow in cerebral artery and femoral artery are analyzed.

Background: Cardiac pulsation propels blood through the cerebrovascular network to maintain cerebral homeostasis. The cerebrovascular network is uniquely surrounded by paravascular cerebrospinal fluid (pCSF), which plays a crucial role in waste removal, and its flow is suspected to be driven by arterial pulsations. Despite its importance, the relationship between vascular and paravascular fluid dynamics throughout the cardiac cycle remains poorly understood in humans., Methods: In this study, we developed a non-invasive neuroimaging approach to investigate the coupling between pulsatile vascular and pCSF dynamics within the subarachnoid space of the human brain. Resting-state functional MRI (fMRI) and dynamic diffusion-weighted imaging (dynDWI) were retrospectively cardiac-aligned to represent cerebral hemodynamics and pCSF motion, respectively. We measured the time between peaks (∆TTP) in d d ϕ f M R I and dynDWI waveforms and measured their coupling by calculating the waveforms correlation after peak alignment (correlation at aligned peaks). We compared the ∆TTP and correlation at aligned peaks between younger [mean age: 27.9 (3.3) years, n = 9] and older adults [mean age: 70.5 (6.6) years, n = 20], and assessed their reproducibility within subjects and across different imaging protocols., Results: Hemodynamic changes consistently precede pCSF motion. ∆TTP was significantly shorter in younger adults compared to older adults (-0.015 vs. -0.069, p < 0.05). The correlation at aligned peaks were high and did not differ between younger and older adults (0.833 vs. 0.776, p = 0.153). The ∆TTP and correlation at aligned peaks were robust across fMRI protocols (∆TTP: -0.15 vs. -0.053, p = 0.239; correlation at aligned peaks: 0.813 vs. 0.812, p = 0.985) and demonstrated good to excellent within-subject reproducibility (∆TTP: intraclass correlation coefficient = 0.36; correlation at aligned peaks: intraclass correlation coefficient = 0.89)., Conclusion: This study proposes a non-invasive technique to evaluate vascular and paravascular fluid dynamics. Our findings reveal a consistent and robust cardiac pulsation-driven coupling between cerebral hemodynamics and pCSF dynamics in both younger and older adults., (© 2024. The Author(s).)

Introduction: The effect of pump flow type on perfusion in coronary surgery using cardiopulmonary bypass (CPB) is discussed. We aimed to evaluate the effect of pump flow type on cognitive functions with neurocognitive function tests., Methods: One hundred patients who underwent isolated coronary artery bypass surgery between November 2020 and July 2021 were divided into two equa groups. Groups were formed according to pump flow type pulsatile (Group 1) and non-pulsatile (Group 2). Clock drawing test (CDT) and standardized mini mental test (SMMT) were performed on the patients in both groups in the preoperative period, on the 1st preoperative day, and on the day before discharge. Neurocognitive effects were compared with all follow-up parameters., Results: There was no difference between the groups in terms of demographic data and in terms of neurocognitive tests performed before the operation. SMMT on postoperative day 1 (Group I: 27.64 ± 1.05; Group II: 24.44 ± 1.64; P=0.001) and CDT (Group I: 5.4 ± 0.54; Group II: 4 .66 ± 0.52; P=0.001), and SMMT on the day before discharge (Group I: 27.92 ± 1.16; Group II: 24.66 ± 1.22; P=0.001) and CDT (Group I: 5 It was calculated as .66 ± 0.48; Group II: 5.44 ± 0.5; P=0.001). The duration of intensive care and hospitalization were higher in the non-pulsatile group., Conclusion: We think that the type of pump flow used in coronary artery bypass surgery using CPB is effective in terms of neurocognitive functions and that pulsatile flow makes positive contributions to this issue.

Background: Recent research indicates that there is a high prevalence of heart failure with preserved ejection fraction in patients with peripheral artery disease. We hypothesized that endovascular treatment (EVT) of flow-limiting peripheral stenosis improves left ventricular (LV) diastolic function., Methods: Thirty patients with symptomatic peripheral artery disease and heart failure with preserved ejection fraction according to Heart Failure Association-preserved ejection fraction score who were scheduled for EVT or angiography were investigated at baseline, the day after EVT (n=25) or angiography (control, n=5), and at 4 months follow-up. Peripheral hemodynamics were determined by the total peripheral resistance, common femoral artery flow, and ankle brachial index. Aortic function was measured by arterial compliance, augmentation index, and pulse wave velocity. Aortic pulsatile load was estimated as the characteristic impedance of the proximal aorta and the magnitude of wave reflection (reflection coefficient). LV mass index, LV mean wall thickness, and systolic and diastolic function were assessed using echocardiography. Patient-centered outcomes were treadmill walking distance and New York Heart Association class., Results: After EVT, peripheral hemodynamics changed significantly with a decrease in total peripheral resistance and an increase in common femoral artery flow and ankle brachial index. Aortic function improved after EVT, with significantly reduced augmentation index and pulse wave velocity and increased compliance immediately and at follow-up, resulting in a reduction in aortic pulsatile load (characteristic impedance of the proximal aorta and reflection coefficient). Concurrently, LV diastolic function improved after EVT compared with control, acutely and at follow-up, with increased septal and lateral e´ velocities and decreased E / e ´ and left atrial volume index. The LV mass index and LV mean wall thickness decreased at follow-up. The New York Heart Association class and treadmill walking distance improved post-EVT at follow-up. Augmentation index, pulse wave velocity, and arterial compliance were identified as independent contributors to E / e ´., Conclusions: Endovascular treatment of flow-limiting iliofemoral stenosis reduces aortic pulsatile load and concurrently lowers total peripheral resistance. This beneficial effect is associated with an acute and sustained improvement of left ventricular diastolic function., Registration: URL: http://www.clinicaltrials.gov; Unique identifier: NCT02728479., Competing Interests: None.

Severe right heart failure, often overlooked and challenging to manage, has prompted a growing interest in innovative approaches to provide functional support. This study uses experimentation in large porcine models to introduce a novel prototype of a pulsatile mechanical circulatory support device and document its effects when deployed as a right ventricular assist device (RVAD). The pulsatile ventricular assist platform (pVAP), featuring a membrane pump driven by an intra-aortic balloon pump console, actively generates pulsatile flow to propel right ventricular blood into the pulmonary artery. This novel prototype demonstrates promising potential in addressing the challenges of right heart failure management. After preliminary in vitro assessments, the pVAP was tested on seven porcine models in a healthy state and after the induction of right ventricular failure. During the procedure, a set of standard ( ie , standard-of-care) hemodynamic measurements was obtained. Additionally, invasive pressure-volume loop analysis was employed to examine left ventricular hemodynamics. Results indicated that activation of the pVAP during right ventricular failure significantly improved systemic hemodynamics and enhanced left ventricular function. This study sheds light on the potential of the pVAP in managing right heart failure., Competing Interests: O.M. is the CEO of PulseCath BV. M.B. receives personal fees from PulseCath BV. The other authors have no conflicts of interest to report., (Copyright © ASAIO 2024.)

Blood pressure or flow measurements have been associated with vascular health and cognitive function. We proposed that energetic hemodynamic parameters may provide a more nuanced understanding and stronger correlation with cognitive function, in comparisons with conventional aortic and carotid pressure and flow parameters. The study comprised 1858 participants, in whom we assessed cognitive function via MoCA method, and measured central aortic and carotid pressure and flow waveforms. In addition to various pressure and flow parameters, we calculated energetic hemodynamic parameters through integration of pressure multiplying flow with respect to time. Energetic hemodynamic parameters, particularly aortic and carotid mean and pulsatile energy and pulsatility index (PI), were significantly associated with MoCA score more than any aortic and carotid pressure and flow parameters, after adjusting for age, sex, education, depression score, heart rate, BMI, HDL-cholesterol, and glucose levels. MoCA exhibited a strong positive relationship with carotid mean energy (standardized beta = 0.053, P = 0.0253) and a negative relationship with carotid energy PI (standardized beta = -0.093, P = 0.0002), exceeding the association with all traditional pressure- or flow-based parameters. Aortic pressure reflection coefficient at the aorto-carotid junction was positively correlated with mean carotid energy and negatively correlated with PI. Aortic characteristic impedance positively correlated with carotid energy PI but not mean energy. Our research indicates that energetic hemodynamic parameters, particularly carotid mean energy and carotid energy PI, have a stronger association with MoCA scores than traditional pressure- or flow-based metrics. This correlation with cognitive function is notably influenced by the properties of the aorto-carotid interface., (© 2024. The Author(s).)

Background: Cerebrospinal fluid (CSF) dynamics are increasingly studied in aging and neurological disorders. Models of CSF-mediated waste clearance suggest that altered CSF dynamics could play a role in the accumulation of toxic waste in the CNS, with implications for Alzheimer's disease and other proteinopathies. Therefore, approaches that enable quantitative and volumetric assessment of CSF flow velocities could be of value. In this study we demonstrate the feasibility of 4D flow MRI for simultaneous assessment of CSF dynamics throughout the ventricular system, and evaluate associations to arterial pulsatility, ventricular volumes, and age., Methods: In a cognitively unimpaired cohort (N = 43; age 41-83 years), cardiac-resolved 4D flow MRI CSF velocities were obtained in the lateral ventricles (LV), foramens of Monro, third and fourth ventricles (V3 and V4), the cerebral aqueduct (CA) and the spinal canal (SC), using a velocity encoding (venc) of 5 cm/s. Cerebral blood flow pulsatility was also assessed with 4D flow (venc = 80 cm/s), and CSF volumes were obtained from T1- and T2-weighted MRI. Multiple linear regression was used to assess effects of age, ventricular volumes, and arterial pulsatility on CSF velocities., Results: Cardiac-driven CSF dynamics were observed in all CSF spaces, with region-averaged velocity range and root-mean-square (RMS) velocity encompassing from very low in the LVs (RMS 0.25 ± 0.08; range 0.85 ± 0.28 mm/s) to relatively high in the CA (RMS 6.29 ± 2.87; range 18.6 ± 15.2 mm/s). In the regression models, CSF velocity was significantly related to age in 5/6 regions, to CSF space volume in 2/3 regions, and to arterial pulsatility in 3/6 regions. Group-averaged waveforms indicated distinct CSF flow propagation delays throughout CSF spaces, particularly between the SC and LVs., Conclusions: Our findings show that 4D flow MRI enables assessment of CSF dynamics throughout the ventricular system, and captures independent effects of age, CSF space morphology, and arterial pulsatility on CSF motion., (© 2024. The Author(s).)

Perivascular cerebrospinal fluid (pCSF) flow is a key component of the glymphatic system. Arterial pulsation has been proposed as the main driving force of pCSF influx along the superficial and penetrating arteries; however, evidence of this mechanism in humans is limited. We proposed an experimental framework of dynamic diffusion tensor imaging with low b-values and ultra-long echo time (dynDTI low-b ) to capture pCSF flow properties during the cardiac cycle in human brains. Healthy adult volunteers (aged 17-28 years; seven men, one woman) underwent dynDTI low-b using a 3T scanner (MAGNETOM Prisma, Siemens Healthcare, Erlangen, Germany) with simultaneously recorded cardiac output. The results showed that diffusion tensors reconstructed from pCSF were mainly oriented in the direction of the neighboring arterial flow. When switching from vasoconstriction to vasodilation, the axial and radial diffusivities of the pCSF increased by 5.7 % and 4.94 %, respectively, suggesting that arterial pulsation alters the pCSF flow both parallel and perpendicular to the arterial wall. DynDTI low-b signal intensity at b=0 s/mm 2 (i.e., T2-weighted, [S(b=0 s/mm 2 )]) decreased in systole, but this change was ∼7.5 % of a cardiac cycle slower than the changes in apparent diffusivity, suggesting that changes in S(b=0 s/mm 2 ) and apparent diffusivity arise from distinct physiological processes and potential biomarkers associated with perivascular space volume and pCSF flow, respectively. Additionally, the mean diffusivities of white matter showed cardiac-cycle dependencies similar to pCSF, although a delay relative to the peak time of apparent diffusivity in pCSF was present, suggesting that dynDTI low-b could potentially reveal the dynamics of magnetic resonance imaging-invisible pCSF surrounding small arteries and arterioles in white matter; this delay may result from pulse wave propagation along penetrating arteries. In conclusion, the vasodilation-induced increases in axial and radial diffusivities of pCSF and mean diffusivities of white matter are consistent with the notion that arterial pulsation can accelerate pCSF flow in human brain. Furthermore, the proposed dynDTI low-b technique can capture various pCSF dynamics in artery pulsation., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024. Published by Elsevier Inc.)

Objectives: Early shock reversal is crucial to improve patient outcomes. Capillary refill time (CRT) is clinically important to identify and monitor shock in children but has issues with inconsistency. To minimize inconsistency, we evaluated a CRT monitoring system using an automated compression device. Our objective was to determine proper compression pressure in children., Methods: Clinician force for CRT was collected during manual CRT measurement as a reference for automated compression in a previous study (12.9 N, 95% confidence interval, 12.5-13.4; n = 454). An automated compression device with a soft inflation bladder was fitted with a force sensor. We evaluated the effectiveness of the automated pressure to eliminate pulsatile blood flow from the distal phalange. Median and variance of CRT analysis at each pressure was compared., Results: A comparison of pressures at 300 to 500 mm Hg on a simulated finger yielded a force of 5 to 10 N, and these pressures were subsequently used for automated compression for CRT. Automated compression was tested in 44 subjects (median age, 33 months; interquartile range [IQR], 14-56 months). At interim analysis of 17 subjects, there was significant difference in the waveform with residual pulsatile blood flow (9/50: 18% at 300 mm Hg, 5/50:10% at 400 mm Hg, 0/51: 0% at 500 mm Hg, P = 0.008). With subsequent enrollment of 27 subjects at 400 and 500 mm Hg, none had residual pulsatile blood flow. There was no difference in the CRT: median 1.8 (IQR, 1.06-2.875) in 400 mm Hg vs median 1.87 (IQR, 1.25-2.8325) in 500 mm Hg, P = 0.81. The variance of CRT was significantly larger in 400 mm Hg: 2.99 in 400 mm Hg vs. 1.35 in 500 mm Hg, P = 0.02, Levene's test. Intraclass correlation coefficient for automated CRT was 0.56 at 400 mm Hg and 0.78 at 500 mm Hg., Conclusions: Using clinician CRT measurement data, we determined either 400 or 500 mm Hg is an appropriate pressure for automated CRT, although 500 mm Hg demonstrates superior consistency., Competing Interests: The remaining authors have disclosed that they do not have any conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Neurovascular 4D-Flow MRI enables non-invasive evaluation of cerebral hemodynamics including measures of cerebral blood flow (CBF), vessel pulsatility index (PI), and cerebral pulse wave velocity (PWV). 4D-Flow measures have been linked to various neurovascular disorders including small vessel disease and Alzheimer's disease; however, physiological and technical sources of variability are not well established. Here, we characterized sources of diurnal physiological and technical variability in cerebral hemodynamics using 4D-Flow in a retrospective study of cognitively unimpaired older adults (N = 750) and a prospective study of younger adults (N = 10). Younger participants underwent repeated MRI sessions at 7am, 4 pm, and 10 pm. In the older cohort, having an MRI earlier on the day was significantly associated with higher CBF and lower PI. In prospective experiments, time of day significantly explained variability in CBF and PI; however, not in PWV. Test-retest experiments showed high CBF intra-session repeatability (repeatability coefficient (RPC) =7.2%), compared to lower diurnal repeatability (RPC = 40%). PI and PWV displayed similar intra-session and diurnal variability (PI intra-session RPC = 22%, RPC = 24% 7am vs 4 pm; PWV intra-session RPC = 17%, RPC = 21% 7am vs 4 pm). Overall, CBF measures showed low technical variability, supporting diurnal variability is from physiology. PI and PWV showed higher technical variability but less diurnal variability., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: S.C. Johnson served on an advisory board for Roche Diagnostics in 2018 for which he received an honorarium and is principal investigator of an equipment grant from Roche. He conducts tau imaging in NIH funded studies as well as a study funded by Cerveau Technologies using radioligand precursor material supplied by Cerveau Technologies.

Aims: Right ventricular failure after left ventricular assist device (LVAD) implantation is a major concern that remains challenging to predict. We sought to investigate the relationship between preoperative pulmonary artery pulsatility index (PAPi) and mortality after LVAD implantation., Methods and Results: A retrospective analysis of the ASSIST-ICD multicentre registry allowed the assessment of PAPi before LVAD according to the formula [(systolic pulmonary artery pressure - diastolic pulmonary artery pressure)/central venous pressure]. The primary endpoint was survival at 3 months, according to the threshold value of PAPi determined by the receiver operating characteristic (ROC) curve. A multivariate analysis including demographic, echographic, haemodynamic, and biological variables was performed to identify predictive factors for 2 year mortality. One hundred seventeen patients were included from 2007 to 2021. The mean age was 58.45 years (±13.16), with 15.4% of women (sex ratio 5.5). A total of 53.4% were implanted as bridge to transplant and 43.1% as destination therapy. Post-operative right ventricular failure was observed in 57 patients (48.7%), with no significant difference between survivors and non-survivors at 1 month (odds ratio 1.59, P = 0.30). The median PAPi for the whole study population was 2.83 [interquartile range 1.63-4.69]. The threshold value of PAPi determined by the ROC curve was 2.84. Patients with PAPi ≥ 2.84 had a higher survival rate at 3 months [PAPi < 2.84: 58.1% [46.3-72.8%] vs. PAPi ≥ 2.84: 89.1% [81.1-97.7%], hazard ratio (HR) 0.08 [0.02-0.28], P < 0.01], with no significant difference after 3 months (HR 0.67 [0.17-2.67], P = 0.57). Other predictors of 2 year mortality were systemic hypertension (HR 4.22 [1.49-11.97], P < 0.01) and diabetes mellitus (HR 4.90 [1.83-13.14], P < 0.01). LVAD implantation as bridge to transplant (HR 0.18 [0.04-0.74], P = 0.02) and heart transplantation (HR 0.02 [0.00-0.18], P < 0.01) were associated with a higher survival rate at 2 years., Conclusions: Preoperative PAPi < 2.84 was associated with a higher risk of early mortality after LVAD implantation without impacting 2 year outcomes among survivors., (© 2024 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

Recent computational and experimental studies of intracranial aneurysms have revealed potential mechanisms of aneurysm bruits and murmurs, driven by flow instabilities rather than by stable pulsatile flow. Some of these studies have been conducted under the assumption of constant flow rate (steady flow); however the validity of this assumption has not been evaluated for high-frequency flow instability, or vibrations from fluid-structure interaction (FSI) simulations. We evaluated the time-averaged wall shear stress, flow instability and vibration amplitude of steady flow simulations, performed at both cycle-averaged and peak-systolic flow rates, and compared these to recent pulsatile FSI simulations. Wall shear stress fields of pulsatile flow (time-averaged and peak values) were well-approximated by the respective steady-flow FSI simulations, and the spatial distribution and frequency content of flow instability and vibrations were reasonably approximated by the steady flow simulations at peak-systolic flow rates. However, the level of flow instability and vibration was generally over-predicted by the steady flow simulations at peak-systolic flow rates as flow remained unstable for longer than in the pulsatile simulation, while no flow instability was detected for steady flow at cycle-averaged flow rates. Additionally, the amplitude of flow instability and vibration fluctuated considerably in the steady flow simulations, while the pulsatile simulations exhibited consistent vibration amplitudes (less than 10 % variation at peak systole between cycles). Finally, steady flow simulations at peak-systolic conditions required 2-3x more compute time than the pulsatile simulations for the same time duration. Therefore, we recommend using pulsatile flow simulations when investigating vibrations and flow instabilities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Purpose: Directly imaging the function of cerebral perforating arteries could provide valuable insight into the pathology of cerebral small vessel diseases (cSVD). Arterial pulsatility has been identified as a useful biomarker for assessing vascular dysfunction. In this study, we investigate the feasibility and reliability of using dual velocity encoding (VENC) phase-contrast MRI (PC-MRI) to measure the pulsatility of cerebral perforating arteries at 7 T., Methods: Twenty participants, including 12 young volunteers and 8 elder adults, underwent high-resolution 2D PC-MRI scans with VENCs of 20 cm/s and 40 cm/s at 7T. The sensitivity of perforator detection and the reliability of pulsatility measurement of cerebral perforating arteries using dual-VENC PC-MRI were evaluated by comparison with the single-VENC data. The effects of temporal resolution in the PC-MRI acquisition and aging on the pulsatility measurements were investigated., Results: Compared to the single VENCs, dual-VENC PC-MRI provided improved sensitivity of perforator detection and more reliable pulsatility measurements. Temporal resolution impacted the pulsatility measurements, as decreasing temporal resolution led to an underestimation of pulsatility. Elderly adults had elevated pulsatility in cerebral perforating arteries compared to young adults, but there was no difference in the number of detected perforators between the two age groups., Conclusion: Dual-VENC PC-MRI is a reliable imaging method for the assessment of pulsatility of cerebral perforating arteries, which could be useful as a potential imaging biomarker of aging and cSVD., (© 2024 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Unruptured intracranial aneurysms are common in the general population, and many uncertainties remain when predicting rupture risks and treatment outcomes. One of the cutting-edge tools used to investigate this condition is computational fluid dynamics (CFD). However, CFD is not yet mature enough to guide the clinical management of this disease. In addition, recent studies have reported significant flow instabilities when refined numerical methods are used. Questions remain as to how to properly simulate and evaluate this flow, and whether these instabilities are really turbulence. The purpose of the present study is to evaluate the impact of the simulation setup on the results and investigate the occurrence of turbulence in a cerebral artery with an aneurysm. For this purpose, direct numerical simulations were performed with up to 200 cardiac cycles and with data sampling rates of up to 100,000 times per cardiac cycle. Through phase-averaging or triple decomposition, the contributions of turbulence and of laminar pulsatile waves to the velocity, pressure and wall shear stress fluctuations were distinguished. For example, the commonly used oscillatory shear index was found to be closely related to the laminar waves introduced at the inlet, rather than turbulence. The turbulence energy cascade was evaluated through energy spectrum estimates, revealing that, despite the low flow rates and Reynolds number, the flow is turbulent near the aneurysm. Phase-averaging was shown to be an approach that can help researchers better understand this flow, although the results are highly dependent on simulation setup and post-processing choices., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: In lower extremity peripheral artery disease (PAD), the ankle-brachial index (ABI) is an easily reproducible diagnostic tool for PAD, but it loses reliability when > 1.4 due to calcification of the vessel wall. Patients with diabetes are at higher risk for wall calcification. In order to overcome the limitation and reliability of ABI, particularly in patients with diabetes, we decided to assess resistive (RI) and pulsatility index (PI) by ultrasound doppler of the dorsal metatarsal artery (DMA)., Results: We therefore analyzed 51 legs (32 patients), evaluating the correlation between PI, RI, and ABI. Patients with diabetes were 21 (65.6 %), accounting for 33 legs (64.7 %). Out of 51 legs assessed, 37 (72.5 %) cases had compressible arteries, whereas in 14 legs (27.5 %) ABI was not calculable due to wall calcification. PAD was significantly associated with lower both RI and PI of the DMA (both p < 0.000). RI, but not PI, showed a significant correlation (r = 0.535) with ABI, when ABI was less than 1.4, but not when ABI > 1.4. When analyzed separately, patients with diabetes showed a similar figure in comparison with those without diabetes (r = 0.600), RI, but not PI, showed a significant correlation with ABI., Conclusion: Dorsal metatarsal artery resistive index (MARI) showed a significant inverse correlation with PAD, similarly to ABI, irrespective of the presence of diabetes. MARI seems to be an effective screening tool for PAD even in patients with wall calcification. Further studies are needed for confirming the results of the present pilot study., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Functional abnormalities of the ascending aorta (AA) have been mainly reported in young patients who underwent arterial switch operation (ASO) for transposition of the great arteries (TGA)., Objectives: To compare systolic, diastolic brachial and central blood pressures (bSBP, bDBP, cSBP, cDBP), aortic biomechanical parameters, and left ventricular (LV) afterload criteria in adult ASO patients with healthy controls and to assess their relationships with LV remodeling and aortic size., Materials and Methods: Forty-one prospectively enrolled patients (16.8 to 35.8 years) and 41 age- and sex-matched healthy volunteers underwent cardiac MRI to assess LV remodeling with simultaneous brachial BP estimation. After MRI, carotid-femoral tonometry was performed to measure pulse wave velocity (cfPWV), cSBP and cDBP for further calculation of pulse pressure (cPP), AA distensibility (AA D ), and AA and LV elastance (AA E , LV E )., Results: bSBP, bDBP, cSBP,cDBP and cPP were all significantly higher in ASO group than in controls: cSBP (116.5 ± 13.8 vs 106.1 ± 12.0, p < 0.001), cDBP (72.5 ± 6.9 vs 67.1 ± 9.4, p = 0.002), cPP (44.0 ± 12.1 vs 39.1 ± 8.9, p = 0.003) and not related to aortic size. AA D were decreased in ASO patients vs controls (4.70 ± 2.72 vs 6.69 ± 2.16, p < 0.001). LV mass was correlated with bSBP, cSBP, cPP (ρ = 0.48; p < 0.001), while concentric LV remodeling was correlated with AA E (ρ = 0.60, p < 0.001) and LV E (ρ = 0.32, p = 0.04), but not with distensibility., Conclusion: Even without reaching arterial hypertension, aortic sBP and PP are increased in the adult TGA population after ASO, altering the pulsatile components of afterload and contributing to LV concentric remodeling., (Copyright © 2023. Published by Elsevier B.V.)

Background: At present, the most effective treatment for symptomatic moyamoya disease (MMD) is surgery. However, the high incidence of postoperative complications is a serious problem plaguing the surgical treatment of MMD, especially the acute cerebral infarction. Decreased cerebrovascular reserve is an independent risk factor for ischemic infarction, and the pulsatility index (PI) of transcranial Doppler (TCD) is a common intuitive index for evaluating intracranial vascular compliance. However, the relationship between PI and the occurrence of ischemic stroke after operation is unclear., Objective: To explore whether the PI in the middle cerebral artery (MCA) could serve as a potential predictor for the occurrence of ischemic infarction after bypass surgery in MMD., Methods: We performed a retrospective analysis of data from 71 patients who underwent combined revascularization surgery, including superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis and encephalo-duro-myo-synangiosis (EDMS). The patients were divided into two groups according to the median of ipsilateral MCA-PI before operation, low PI group (MCA-PI < 0.614) and high PI group (MCA-PI ≥ 0.614). Univariate and multivariate regression analysis were used to explore risk factors affecting the occurrence of postoperative cerebral infarction., Results: Among the 71 patients with moyamoya disease, 11 patients had cerebral infarction within one week after revascularization. Among them, 10 patients' ipsilateral MCA-PI were less than 0.614, and another one's MCA- PI is higher than 0.614. Univariate analysis showed that the lower ipsilateral MCA-PI (0.448 ± 0.109 vs. 0.637 ± 0.124; P = 0.001) and higher Suzuki stage (P = 0.025) were linked to postoperative cerebral infarction. Multivariate analysis revealed that lower ipsilateral MCA-PI was an independent risk factor for predicting postoperative cerebral infarction (adjusted OR = 14.063; 95% CI = 6.265 ~ 37.308; P = 0.009)., Conclusions: A lower PI in the ipsilateral MCA may predict the cerebral infarction after combined revascularization surgery with high specificity. And combined revascularization appears to be safer for the moyamoya patients in early stages., (© 2024. The Author(s).)

Competing Interests: Financial/Nonfinancial Disclosures None declared.

Mechanisms behind the protective effects of aerobic exercise on brain health remain elusive but may be vascular in origin and relate to cerebral pulsatility. This pilot study investigated the effects of 12-wk aerobic exercise training on cerebral pulsatility and its vascular contributors (large artery stiffness, characteristic impedance) in at-risk middle-aged adults. Twenty-eight inactive middle-aged adults with elevated blood pressure or stage 1 hypertension were assigned to either moderate/vigorous aerobic exercise training (AET) for 3 days/wk or no-exercise control (CON) group. Middle cerebral artery (MCA) pulsatility index (PI), large artery (i.e., aorta, carotid) stiffness, and characteristic impedance were assessed via Doppler and tonometry at baseline, 6, and 12 wk, whereas cardiorespiratory fitness (V̇o 2peak ) was assessed via incremental exercise test and cognitive function via computerized battery at baseline and 12 wk. V̇o 2peak increased 6% in AET and decreased 4% in CON ( P < 0.05). Proximal aortic compliance increased ( P = 0.04, partial η 2 = 0.14) and aortic characteristic impedance decreased ( P = 0.02, partial η 2  = 0.17) with AET but not CON. Cerebral pulsatility showed a medium-to-large effect size increase with AET, although not statistically significant ( P = 0.07, partial η 2  = 0.11) compared with CON. Working memory reaction time improved with AET but not CON ( P = 0.02, partial η 2  = 0.20). Our data suggest 12-wk AET elicited improvements in central vascular hemodynamics (e.g., proximal aortic compliance and characteristic impedance) along with apparent, paradoxical increases in cerebral pulsatile hemodynamics. NEW & NOTEWORTHY We identify differential central versus cerebrovascular responses to 12 wk of aerobic exercise training in middle-aged adults. Although proximal aortic compliance and characteristic impedance improved after 12 wk of exercise, cerebral pulsatility tended to unexpectedly increase. These data suggest short-term aerobic exercise training may lead to more immediate benefits in the central vasculature, whereas longer duration exercise training may be required for beneficial changes in pulsatility within the cerebrovasculature.

Objective: Our aim was to investigate the significance of cerebro-placento-uterine ratio CPUR, a new Doppler index, and fetal cardiac parameters (Mod MPI, EFT) in early-onset preeclampsia (EOPE) and to examine whether these parameters are related to perinatal outcome., Study Design: Forty participants diagnosed with EOPE (preeclampsia cases diagnosed before 34 weeks of gestation) and 40 healthy pregnant women were included in this study. Demographic data were recorded. Doppler parameters such as middle cerebral artery (MCA), umbilical artery (UA), and uterine artery (Ut-A), and left modified myocardial performance index (Mod-MPI) and epicardial fat thickness (EFT) were measured. Cerebroplacental ratio (CPR) was determined by dividing MCA pulsatility index (PI) by UA PI. CPUR was calculated as the ratio of CPR to mean UtA-PI (CPUR = CPR/UtA-PI). All parameters were compared between the EOPE and control groups. Correlation tests were used to examine the relationship between Doppler parameters and perinatal outcome. p values less than 0.05 were considered statistically significant., Results: The pulsatility index of the middle cerebellar artery, CPUR and CPR values were statistically lower in the EOPE group than in the control group (p = 0.002; p = <0.001; p = <0.001; respectively). No statistical differences were found between groups for isovolumetric contraction time (ICT), isovolumetric relaxation time (IRT), ejection time (ET), left mod-MPI, EFT (p = 0.117; p = 0.093; p = 0.398; p = 0.882; p = 0.202, respectively). Umbilical artery Doppler pulsatility index (PI), mean uterine artery Doppler pulsatility index (PI), were higher in the EOPE group than in the control group (p = 0.006; and p = <0.001, respectively). The CPUR value for predicting EOPE was ≤1.3652 with 74. 4% sensitivity and 94.9% specificity. Positive correlations were found between CPUR, CPR, and some neonatal parameters., Conclusion: CPUR, a new index combining fetal and uterine Doppler indices, may add contribution to predict adverse perinatal outcome and EOPE., (© 2024 Wiley Periodicals LLC.)

Objectives: The aim of this study was to evaluate if the presence of a pulsatile femoral vein pattern is an indicator of venous congestion in the intensive care unit (ICU)., Design: Retrospective observational study., Setting: Three medico-surgical university-affiliated ICUs., Participants: Adult patients who had an ultrasound evaluation at several time points during their ICU stay: at baseline (within 24 hours of admission to ICU), daily during their ICU stay, and within 24 hours before ICU discharge., Interventions: At each time point, the hemodynamic, respiratory, and cardiac ultrasound parameters were recorded. The common femoral vein was studied with pulsed-wave Doppler at the level of the femoral trigonum, with high frequency (5-13 MHz) linear array vascular probe and venous vascular mode, in supine patients., Measurements and Main Results: One hundred eight patients who underwent 400 ultrasound evaluations (3.7 ± 1 ultrasound evaluations per patient) during their ICU stay were included. Seventy-nine of 108 patients (73%) had a pulsatile femoral vein pattern at least at 1 time point. The multivariable mixed effects logistic regression model demonstrated an association among pulsatile femoral vein pattern, body mass index (OR: 0.91[95% CI 0.85-0.96], p = 0.002), inferior vena cava mean diameter (OR: 2.35 [95% CI 1.18-4.66], p = 0.014), portal vein pulsatility (OR: 2.3 [95% CI 1.2-4.4], p = 0.012), and congestive renal vein flow pattern (OR: 4.02 [95% CI 2.01-8.03], p < 0.001). The results were confirmed by principal component analysis., Conclusion: In the ICU, a pulsatile femoral vein pattern is associated with parameters of venous congestion, independently of the patient's volume status, and ventilatory treatment. These results suggest the femoral vein Doppler pulsatility as a parameter of congestion in ICU patients., Competing Interests: Declaration of competing interest None., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background and Aim: In hydrocephalus patients, after ventriculoperitoneal (VP) shunt, decrease in pulsatility index (PI) correlates with decrease in ventricle size. Also, increase in PI is noted in obstructed or malfunctioning VP shunts. However, previous studies were either done in infants and children or included patients of all age groups. Our aim was to compare PI before and after successful VP shunt surgery in adult patients and also the trend of transcranial Doppler (TCD) parameters for 3 days after surgery., Materials and Methods: A prospective, observational study was done in 20 adult patients undergoing VP shunt. Clinical features, vitals, Evans index, and TCD parameters were noted in the preoperative period. A computed tomography (CT) head was repeated 4-6 h after surgery, and the position of ventricular end of shunt was confirmed and Evans index was calculated. The vitals and TCD parameters were noted at same time and for the next 2 days. Repeated measures analysis of variance (ANOVA) and paired t-test were uses for statistical analysis., Results: A total of 18 patients were included for statistical analysis. The mean preoperative PI was 1.19 ± 0.24 and the postoperative PI after surgery was 0.97 ± 0.17, 0.97 ± 0.23, and 0.94 ± 0.21 (P = 0.0039) on postoperative day (POD) 1 (POD1), POD2, and POD3, respectively. The mean preoperative value of Evans index was 0.37 ± 0.06 and there was statistically significant (P = < 0.001) reduction to 0.33 ± 0.07 after VP shunt surgery. The change in PI and change in Evans index were found to be positively correlated (r = 0.34 and P = 0.0013)., Conclusions: The decrease in PI after VP shunt surgery correlates with decrease in ventricular size. Any increase in PI in the postoperative period should raise the suspicion of malfunctioning of VP shunt., (Copyright © 2024 Copyright: © 2024 Neurology India, Neurological Society of India.)

Objective: This study investigated the correlation between the pulsatility index (PI) of the middle cerebral artery with the total burden of cerebral small vessel disease and cognitive impairment., Method: Information on patients hospitalized in the Department of Neurology was collected retrospectively. These patients had complete clinical and laboratory data. The middle cerebral artery PI was measured using transcranial Doppler, a Mini-Mental State Examination (MMSE) was used to assess cognitive function, and the total cerebral small vessel disease burden was assessed using magnetic resonance imaging. Patients were grouped according to their scores for total imaging burden of cerebral small vessel disease and cognitive function. Logistic regression analysis assessed the association between the PI, total imaging burden, and cognitive impairment. Spearman analysis was used to evaluate the correlation between the PI and total imaging burden and cognitive impairment, and receiver operating characteristic (ROC) curves were used to determine the predictive value of the PI for cognitive function., Results: The PI was higher in the cognitive impairment (CI) group than in the no-CI group. Binary logistic regression analysis showed that increased PI was an independent risk factor for CI (OR = 1.582; 95% CI: 1.043-2.401; p = .031) and total imaging burden (OR = 1.842; 95% CI: 1.274-2.663; p = .001). Spearman analysis found that the PI correlated negatively with the MMSE score (r = -.627, p < .001). ROC curve analysis showed the PI predicted CI with an area under the curve of 0.784. The PI combined with the total imaging burden predicted CI in cerebral small vessel disease with an area under the curve of 0.832., Conclusion: An increased PI was associated with CI and a high imaging burden in cerebral small vessel disease patients. The PI combined with the total burden score shows a high predictive value for CI., (© 2024 The Authors. Brain and Behavior published by Wiley Periodicals LLC.)

In this work, we investigated the influence of the bifurcation geometry of the iliac artery on the propagation properties of the pulse wave, and applied software to establish the straight bifurcation and curved bifurcation bi-directional fluid-solid coupling finite element analysis models based on the iliac artery, and compared and analyzed the influence of the bifurcation angle of the blood vessel on the propagation characteristics of the pulse wave. It was found that the bifurcation geometry had a significant effect on the pulse wave propagation in the iliac arteries, and the pressure and velocity pulse wave amplitudes predicted by these two models had a good agreement with that before the vessel bifurcation in a cardiac cycle. The curvilinear bifurcation model predicted the pulse wave amplitude to be lower and the pressure drop to be smaller after the bifurcation, which was more in line with the actual situation of the human body. In addition, the bifurcation point is accompanied by the stress concentration phenomenon in the vessel wall, and there is a transient increase in the velocity pulse waveform amplitude, which was consistent with the fact that the bifurcation site is prone to phenomena such as arterial stenosis and hardening. The preliminary results of this paper will provide some reference for the use of pulse waveforms in the diagnosis of arterial diseases.

Objective: The objective was to analyze the impact of the uterine artery pulsatility index (PI) on pregnancy outcomes by measuring uterine artery blood flow on the day of endometrial transformation in patients undergoing frozen-thawed embryo transfer (FET)., Methods: This was a case-control study. In total, 2,036 patients who underwent FET at the Third Affiliated Hospital of Zhengzhou University from October 2019 to September 2020 were included. The patients were divided into a clinical pregnancy group and a nonclinical pregnancy group according to pregnancy outcome. A multivariate logistic regression model was used to analyze the factors affecting the clinical pregnancy rate. The receiver operating characteristic (ROC) curve was used to determine the optimal mean PI cutoff value of 1.75. After 1:1 propensity score matching (PSM), 562 patients were included. For statistical description and analysis, the patients were divided into two groups: a group with a mean PI > 1.75 and a group with a mean PI ≤ 1.75., Results: The clinical pregnancy group included 1,218 cycles, and the nonclinical pregnancy group included 818 cycles. There were significant differences in female age (P<0.01), infertility type (P=0.04), baseline follicle-stimulating hormone level (P=0.04), anti-Müllerian hormone (AMH) level (P<0.01), antral follicle count (P<0.01), number of transferred embryos (P=0.045) and type of transferred embryo (P<0.01). There was no significant difference in the mean bilateral PI (1.98 ± 0.34 vs. 1.95 ± 0.35, P=0.10). The multivariate analysis results showed that maternal age (AOR=0.95, 95% CI=0.93-0.98, P<0.01), AMH level (AOR=1.00, 95% CI=1.00-1.01, P=0.045), number of transferred embryos (AOR=1.98, 95% CI=1.47-2.70, P<0.01), and type of transferred embryo (AOR=3.10, 95% CI=2.27-4.23, P<0.01) were independent factors influencing the clinical pregnancy rate. The mean PI (AOR=0.85, 95% CI=0.70-1.05; P=0.13) was not an independent factor influencing the clinical pregnancy rate. Participants were divided into two groups according to the mean PI cutoff value of 1.75, and there was no significant difference between the two groups (P > 0.05)., Conclusion: In this study, we found that the uterine artery PI on the day of endometrial transformation in patients undergoing FET is not a good predictor of pregnancy outcomes., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Li, Du, Wu, Wen, Kong, Zhang and Guan.)

To investigate flow conditions in a double-layered carotid artery stent, a bench-top in vitro flow setup including a bifurcation phantom was designed and fabricated. The geometry of the tissue-mimicking phantom was based on healthy individuals. Two identical phantoms were created using 3D-printing techniques and molding with PVA-gel. In one of them, a clinically available CGuard double-layer stent was inserted. Measurements were performed using both continuous and pulsatile flow conditions. Blood flow studies were performed using echoPIV: a novel ultrasound-based technique combined with particle image velocimetry. A maximum deviation of 3% was visible between desired and measured flow patterns. The echoPIV measurements showed promising results on visualization and quantification of blood flow in and downstream the stent. Further research could demonstrate the effects of a double-layered stent on blood flow patterns in a carotid bifurcation in detail., (© 2023. International Federation for Medical and Biological Engineering.)

Continuous flow (CF) left ventricular assist devices (LVAD) operate at a constant speed mode, which could result in increased risk of adverse events due to reduced vascular pulsatility. Consequently, pump speed modulation algorithms have been proposed to augment vascular pulsatility. However, the quantitative local hemodynamic effects on the aorta when the pump is operating with speed modulation using different types of CF-LVADs are still under investigation. The computational fluid dynamics (CFD) study was conducted to quantitatively elucidate the hemodynamic effects on a clinical patient-specific aortic model under different speed patterns of CF-LVADs. Pressure distribution, wall shear stress (WSS), time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and velocity were calculated to compare their differences at constant and pulsatile speeds under centrifugal and axial LVAD support. Results showed that pulse pressure on the aorta was significantly larger under pulsatile speed mode than that under constant speed mode for both CF-LVADs, indicating enhanced aorta pulsatility, as well as the higher peak blood flow velocity on some representative slices of aorta. Pulsatile speed modulation enhanced peak WSS compared to constant speed; high TAWSS region appeared near the branch of left common carotid artery and distal aorta regardless of speed modes and CF-LVADs but these regions also had low OSI; RRT was almost the same for all the cases. This study may provide a basis for the scientific and reasonable selection of the pulsatile speed patterns of CF-LVADs for treating heart failure patients., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Objective: Effective first-trimester screening for pre-eclampsia (PE) can be achieved using a competing-risks model that combines risk factors from the maternal history with multiples of the median (MoM) values of biomarkers. A new model using artificial intelligence through machine-learning methods has been shown to achieve similar screening performance without the need for conversion of raw data of biomarkers into MoM. This study aimed to investigate whether this model can be used across populations without specific adaptations., Methods: Previously, a machine-learning model derived with the use of a fully connected neural network for first-trimester prediction of early (< 34 weeks), preterm (< 37 weeks) and all PE was developed and tested in a cohort of pregnant women in the UK. The model was based on maternal risk factors and mean arterial blood pressure (MAP), uterine artery pulsatility index (UtA-PI), placental growth factor (PlGF) and pregnancy-associated plasma protein-A (PAPP-A). In this study, the model was applied to a dataset of 10 110 singleton pregnancies examined in Spain who participated in the first-trimester PE validation (PREVAL) study, in which first-trimester screening for PE was carried out using the Fetal Medicine Foundation (FMF) competing-risks model. The performance of screening was assessed by examining the area under the receiver-operating-characteristics curve (AUC) and detection rate (DR) at a 10% screen-positive rate (SPR). These indices were compared with those derived from the application of the FMF competing-risks model. The performance of screening was poor if no adjustment was made for the analyzer used to measure PlGF, which was different in the UK and Spain. Therefore, adjustment for the analyzer used was performed using simple linear regression., Results: The DRs at 10% SPR for early, preterm and all PE with the machine-learning model were 84.4% (95% CI, 67.2-94.7%), 77.8% (95% CI, 66.4-86.7%) and 55.7% (95% CI, 49.0-62.2%), respectively, with the corresponding AUCs of 0.920 (95% CI, 0.864-0.975), 0.913 (95% CI, 0.882-0.944) and 0.846 (95% CI, 0.820-0.872). This performance was achieved with the use of three of the biomarkers (MAP, UtA-PI and PlGF); inclusion of PAPP-A did not provide significant improvement in DR. The machine-learning model had similar performance to that achieved by the FMF competing-risks model (DR at 10% SPR, 82.7% (95% CI, 69.6-95.8%) for early PE, 72.7% (95% CI, 62.9-82.6%) for preterm PE and 55.1% (95% CI, 48.8-61.4%) for all PE) without requiring specific adaptations to the population., Conclusions: A machine-learning model for first-trimester prediction of PE based on a neural network provides effective screening for PE that can be applied in different populations. However, before doing so, it is essential to make adjustments for the analyzer used for biochemical testing. © 2023 International Society of Ultrasound in Obstetrics and Gynecology., (© 2023 International Society of Ultrasound in Obstetrics and Gynecology.)

Introduction: Fetal growth restriction is known to be related to decreased fetal and placental blood flow. It is not known, however, whether placental size is related to fetal and placental blood flow. We studied the correlations of intrauterine placental volume and placental-fetal-ratio with pulsatility index (PI) in the uterine arteries, fetal middle cerebral artery, and umbilical artery., Methods: We followed a convenience sample of 104 singleton pregnancies, and we measured placental and fetal volumes using magnetic resonance imaging (MRI) at gestational week 27 and 37 (n = 89). Pulsatility index (PI) was measured using Doppler ultrasound. We calculated cerebroplacental ratio as fetal middle cerebral artery PI/umbilical artery PI and placental-fetal-ratio as placental volume (cm 3 )/fetal volume (cm 3 )., Results: At gestational week 27, placental volume was negatively correlated with uterine artery PI (r = -0.237, p = 0.015, Pearson's correlation coefficient), and positively correlated with fetal middle cerebral artery PI (r = 0.247, p = 0.012) and cerebroplacental ratio (r = 0.208, p = 0.035). Corresponding correlations for placental-fetal-ratio were -0.273 (p = 0.005), 0.233 (p = 0.018) and 0.183 (p = 0.064). Umbilical artery PI was not correlated with placental volume. At gestational week 37, we found weaker and no significant correlations between placental volume and the pulsatility indices., Conclusions: Our results suggest that placental size is correlated with placental and fetal blood flow at gestational week 27., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Background: Regular and supervised exercise during pregnancy is worldwide recommended due to its proven benefits, but, during exercise, maternal blood flow is redirected from the viscera to the muscles and how fetal wellbeing may be affected by this redistribution is still not well known., Objective: To analyze the longitudinal effect of a supervised moderate physical exercise program during pregnancy on uteroplacental and fetal Doppler parameters., Methods: This is a planned secondary analysis of an randomized controlled trial (RCT), performed at Hospital Universitario de Torrejón, Madrid, Spain, including 124 women randomized from 12 +0 to 15 +6  weeks of gestation to exercise vs. control group. Fetal umbilical artery (UA), middle cerebral artery, and uterine artery pulsatility index (PI), were longitudinally collected by Doppler ultrasound assessment throughout gestation, and derived cerebroplacental ratio (normalized by z -score), and maternal mean PI in the uterine arteries (normalized by multiplies of the median). Obstetric appointments were scheduled at 12 (baseline, 12 +0 to 13 +5 ), 20 (19 +0 to 24 +2 ), 28 (26 +3 to 31 +3 ) and 35 weeks (32 +6 to 38 +6 ) of gestation. Generalized estimating equations were adjusted to assess longitudinal changes in the Doppler measurements according to the randomization group., Results: No significant differences in the fetal or maternal Doppler measurements were found at any of the different checkup time points studied. The only variable that consistently affected the Doppler standardized values was gestational age at the time of assessment. The evolution of the UA PI z -score during the pregnancy was different in the two study groups, with a higher z -score in the exercise group at 20 weeks and a subsequent decrease until delivery while in the control group it remained stable at around zero., Conclusions: A regular supervised moderate exercise program during pregnancy does not deteriorate fetal or maternal ultrasound Doppler parameters along the pregnancy, suggesting that the fetal well-being is not compromised by the exercise intervention. Fetal UA PI z -score decreases during pregnancy to lower levels in the exercise group compared with the control group.

In this study, we investigate the impact of aortic stenosis on the hemodynamics of pulsatile blood flow within a 3D aortic model. Employing a non-Newtonian Casson model with a hematocrit of 45%, our study introduces a preliminary hypothesis to simulate blood flow dynamics, incorporating both linear elastic and viscoelastic models to define the mechanical characteristics of the artery. Through simulations conducted with Ansys-Cfx (version 15), we utilize a 2-way fluid-structure interaction (FSI) approach, employing a Lagrangian-Eulerian formulation with second-order accuracy. We explore the influence of stenosis severity on variables including velocity profiles, pressure distribution, shear stress, wall displacement, and changes in the OSI parameter. Our investigation encompasses arteries with both elastic and viscoelastic walls. The key findings that arise from our results highlight the viscoelastic model's demonstration of reduced radial wall displacement when compared to the linear elastic model. Additionally, we observe that elevated arterial stenosis percentages lead to the elongation of vortex length, heightened wall shear stress, and increased slope of velocity profiles downstream of the stenosed region. Furthermore, bulky obstruction of viscoelastic arteries as opposed to elastic, resulted in a maximum 5 percent increase in velocity profile and a 29.6% decrease in radial displacement. The zenith of shear stress occurs concomitantly with the velocity's peak within the stenosed area. Viscoelastic arterial wall shear stress at the stenosis site escalates due to the rapid expansion of the stenosis. The viscoelastic wall, responding with a blend of viscous and elastic characteristics to applied stress, undergoes slight deformation in shape. Following stress reduction, the wall gradually reverts to its original form, thus alleviating some of the applied stress. In contrast, the elastic wall retains its altered shape due to stress preservation within the material. Additionally, we ascertain an augmentation in radial displacement corresponding with increased artery stenosis., (© 2023 IOP Publishing Ltd.)

Regulating pulsatile flow is important to achieve optimal separation and mixing and enhanced heat transfer in microfluidic devices, as well as maintaining homeostasis in biological systems. The human aorta, a composite and layered tube made (among others) of elastin and collagen, is an inspiration for researchers who seek an engineering solution for a self-regulation of pulsatile flow. Here, we present a bio-inspired approach showing that fabric-jacketed elastomeric tubes, manufactured using commercially available silicone rubber and knitted textiles, can be used to regulate pulsatile flow. Our tubes are evaluated via incorporation into a mock-circulatory 'flow loop' that replicates the pulsatile fluid flow conditions of an ex-vivo heart perfusion (EVHP) device, a machine used in heart transplants. Pressure waveforms measured near the elastomeric tubing clearly indicated an effective flow regulation. The 'dynamic stiffening' behavior of the tubes during deformation is analyzed quantitatively. Broadly, the fabric jackets allow for the tubes to experience greater magnitudes of pressure and distension without risk of asymmetric aneurysm within the expected operating time of an EVHP. Owing to its highly tunable nature, our design may serve as a basis for tubing systems that require passive self-regulation of pulsatile flow., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background: Continuous follow assist devices (CFAD) are the most commonly used mechanical circulatory support devices. Compared to Pulsatile flow assist devices (PFAD), CFADs deliver a non-physiologic type of flow, which might contribute to complications related to lack of pulsatility in these devices. Moreover, lack of pulsatility complicates the clinical management of these patients who often present with good perfusion but with no palpable pulse and none or a negligible pulse pressure on blood pressure measurement., Methods and Results: Presented here is a concept of a universal converter device that can be added inline other CFADs to convert the flow from continuous to pulsatile, simulating a normal flow and pressure pattern. After initial implantation and stabilization with a CFAD, adding this converter might potentially provide the benefits of pulsatile physiologic flow. The device is made of 2 components connected in parallel, working in tandem in user determined cycles. The continuous flow through a specifically positioned openings create a smooth conversion to a pulsatile flow. This device can convert a continuous flow to a physiologic pulsatile flow to achieve a native-like flow pattern and potentially prevent some CFAD complications., Conclusion: This paper presents the concept of pulsatility generation and simulation for other assist devices. Such a device can be a universal add-on or a supplemental option for CFADs.

Objectives: The mechanism by which aspirin prevents pre-eclampsia is poorly understood, and its effects on biomarkers throughout pregnancy are unknown. We aimed to investigate the effects of aspirin on mean arterial pressure (MAP) and mean uterine artery pulsatility index (UtA-PI) using repeated measures from women at increased risk of preterm pre-eclampsia., Methods: This was a longitudinal secondary analysis of the Combined Multimarker Screening and Randomized Patient Treatment with Aspirin for Evidence-Based Pre-eclampsia Prevention (ASPRE) trial using repeated measures of MAP and UtA-PI. In the trial, 1620 women at increased risk of preterm pre-eclampsia were identified using the Fetal Medicine Foundation algorithm at 11 + 0 to 13 + 6 weeks, of whom 798 were randomly assigned to receive 150 mg/day aspirin and 822 were assigned to receive placebo daily from 11-14 weeks to 36 weeks of gestation or delivery, whichever came first. MAP and UtA-PI were measured at baseline and follow-up visits at 19-24, 32-34 and 36 weeks of gestation. Generalized additive mixed models with treatment by gestational age interaction terms were used to investigate the effects of aspirin on MAP and UtA-PI trajectories over time., Results: Among 798 participants in the aspirin group and 822 in the placebo group, there were 5951 MAP and 5942 UtA-PI measurements. Trajectories of raw and multiples of the median (MoM) values of MAP did not differ significantly between the two groups (MAP MoM analysis: P-value for treatment by gestational age interaction, 0.340). In contrast, trajectories of raw and MoM values of UtA-PI showed a significantly steeper decline in the aspirin group than in the placebo group, with the difference mainly driven by a more pronounced reduction before 20 weeks of gestation (UtA-PI MoM analysis: P-value for treatment by gestational age interaction, 0.006)., Conclusions: In women at increased risk of preterm pre-eclampsia, 150 mg/day aspirin initiated in the first trimester does not affect MAP but is associated with a significant decrease in mean UtA-PI, particularly before 20 weeks of gestation. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology., (© 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.)

Aortic aneurysm is one of the most common aortic diseases that can lead to unfortunate consequences. Numerical simulations have an important role in the prediction of the aftereffects of vascular diseases including aneurysm. In this research, numerical simulation of pulsatile blood flow is performed for a 3-dimensional patient-specific model of a thoracic aortic aneurysm (TAA). Since the choice of blood viscosity model may have a significant impact on the simulation results, the effects of four non-Newtonian models of blood viscosity namely Carreau, Casson, Herschel-Bulkley, power low, and the Newtonian model on the wall shear stress (WSS) distribution, shear rate, and oscillatory shear index (OSI) have been analyzed. Simulation results showed that all the non-Newtonian and Newtonian models generally, predict similar patterns for blood flow and shear rate. At high flow rates in the cardiac cycle, the WSS value for all the models are similar to each other except for the power-law model due to the shear thinning behavior. All models predict high values of OSI on the inner wall of the ascending aorta and broad areas of the inner wall of the aneurysm sac. However, the Newtonian model predicts the OSI less than the non-Newtonian models in some areas of the aneurysm sac. Results indicated that the Newtonian model generally can predict the hemodynamic parameters of the blood flow similar to the non-Newtonian but for more precise analysis and to predict the regions prone to rupture and atherosclerosis, choosing a proper non-Newtonian model is recommended.

This work presents a numerical technique for simulating non-Newtonian blood flow in human's arteries driven by an oscillating pressure gradient. The blood is considered as a thixotropic fluid and its structural properties are considered to obey Moore's thixotropic model as a constitutive equation. The equations of motion are simplified considering the flow laminar, axisymmetric and the fluid incompressible. A numerical solution is presented using finite difference method in order to compute the velocity field and wall shear stress distribution. The numerical results obtained have been validated with the analytical solution available in the literature. Furthermore, the effect of the structural properties, the average of the pressure gradient and the external acceleration on the velocity and wall shear stress distribution is investigated. These results reveal the influence of the different parameters studied on the pipe flow response of the thixotropic fluid.

Pulsatile hemodynamics analyses provide important information about the ventricular-arterial system which cannot be inferred by standard blood pressure measurements. Pulse wave analysis (PWA), wave separation analysis (WSA), and wave power analysis (WPA) characterize arterial hemodynamics with limited preclinical applications. Integrating these tools into preclinical testing may enhance understanding of disease or therapeutic effects on cardiovascular function. We used a canine rapid ventricular pacing (RVP) heart failure model to: (1) Characterize hemodynamics in response to RVP and (2) assess analyses from flow waveforms synthesized from pressure compared to those derived from measured flow. Female canines (n = 7) were instrumented with thoracic aortic pressure transducers, ventricular pacing leads, and an ascending aortic flow probe. Data were collected at baseline, 1 week, and 1 month after RVP onset. RVP progressively reduced stroke volume (SV), the PWA SV estimator, and WSA and WPA pulsatility and wave reflection indices. Indices derived from synthesized flow exhibited similar directional changes and high concordance with measured flow calculations. Our data demonstrate the value of analytical hemodynamic methods to gain deeper insight into cardiovascular function in preclinical models. These approaches can provide complementary value to standard endpoints in evaluating potential effects of pharmaceutical agents intended for human use., (© 2023 Merck Sharp & Dohme LLC and The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Mechanical heart valve (MHV) prostheses present a risk of thromboembolic complications despite antithrombotic therapy. Further steps in the development of more hemocompatible MHVs and new anticoagulants are impeded due to the lack of adequate in-vitro models. With the development of a novel in-vitro model (MarioHeart), a pulsatile flow similar to the arterial circulation is emulated. The MarioHeart design owns unique features as 1) a single MHV within a torus with low surface/volume ratio, 2) a closed loop system, and 3) a dedicated external control system driving the oscillating rotational motion of the torus. For verification purposes, a blood analog fluid seeded with particles was used to assess fluid velocity and flow rate using a speckle tracking method on high-speed video recordings of the rotating model. The flow rate resembled the physiological flow rate in the aortic root, in both shape and amplitude. Additional in-vitro runs with porcine blood showed thrombi on the MHV associated with the suture ring, which is similar to the in-vivo situation. MarioHeart is a simple design which induces well-defined fluid dynamics resulting in physiologically nonturbulent flow without stasis of the blood. MarioHeart seems suitable for testing the thrombogenicity of MHVs and the potential of new anticoagulants., Competing Interests: Disclosure: The authors have no conflicts of interest to report., (Copyright © ASAIO 2023.)

Erythrocyte aggregation (EA) is a highly dynamic, vital phenomenon to interpreting human hemorheology, which would be helpful for the diagnosis and prediction of circulatory anomalies. Previous studies of EA on erythrocyte migration and the Fåhraeus Effect are based on the microvasculature. They have not considered the natural pulsatility of the blood flow or large vessels and mainly focused on shear rate along radial direction under steady flow to comprehend the dynamic properties of EA. To our knowledge, the rheological characteristics of non-Newtonian fluids under Womersley flow have not reflected the spatiotemporal behaviors of EA or the distribution of erythrocyte dynamics (ED). Hence, it needs to interpret the ED affected by temporal and spatial flow variation to understand the effect of EA under Womersley flow. Here, we demonstrated the numerically simulated ED to decipher EA's rheological role in axial shear rate under Womersley flow. In the present study, the temporal and spatial variations of the local EA were found to mainly depend on the axial shear rate under Womersley flow in an elastic vessel, while mean EA decreased with radial shear rate. The localized distribution of parabolic or M-shape clustered EA was found in a range of the axial shear rate profile (-15 to 15s -1 ) at low radial shear rates during a pulsatile cycle. However, the linear formation of rouleaux was realized without local clusters in a rigid wall where the axial shear rate is zero. In vivo, the axial shear rate is usually considered insignificant, especially in straight arteries, but it has a great impact on the disturbed blood flow due to the geometrical properties, such as bifurcations, stenosis, aneurysm, and the cyclic variation of pressure. Our findings regarding axial shear rate provide new insight into the local dynamic distribution of EA, which is a critical player in blood viscosity. These will provide a basis for the computer-aided diagnosis of hemodynamic-based cardiovascular diseases by decreasing the uncertainty in the pulsatile flow calculation., Competing Interests: Declaration of competing interest The authors declare that they do not have any competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier Ltd.. All rights reserved.)