Pulsatile Research Articles

Predictive value of acoustic radiation force impulse imaging in breast cancer after neoadjuvant chemotherapy

ABSTRACT To investigate the predictive value of acoustic radiation force impulse imaging for neoadjuvant chemotherapy in breast cancer. Seventy-eight breast cancer patients treated in our hospital from March 2019 to March 2022 were recruited. They received neoadjuvant chemotherapy and were examined by conventional ultrasound and acoustic radiation force impulse imaging before chemotherapy and after two cycles of chemotherapy. The lesion diameter, intralesional blood flow pulsatility index (PI), resistance index (RI), shear wave velocity (SWV), and change rate (Δlesion diameter, ΔPI, ΔRI, ΔSWV) were compared between the two groups before and after chemotherapy. The receiver operating characteristic curve was drawn to evaluate the predictive power of related parameters on the efficacy of neoadjuvant chemotherapy in breast cancer. After two cycles of neoadjuvant chemotherapy, according to the Miller-Payne grading, 57 cases (73.08%) with significant neoadjuvant chemotherapy response were classified as the response group, and 21 cases (26.92%) with non-significant response were classified as the non-response group. Before and after chemotherapy, the difference in lesion diameter, PI, RI, SWV, and change rate (Δlesion diameter, ΔPI, ΔRI, and ΔSWV) was statistically significant between the two groups (P < 0.05). The area under the curve of ΔSWV in predicting the efficacy of neoadjuvant chemotherapy 0.876 (95%CI 0.781 ~ 0.939) was significantly higher than that of Δlesion diameter 0.652 (95%CI 0.535 ~ 0.756), that of ΔPI 0.712 (95%CI 0.599 ~ 0.809), and that of ΔRI 0.678 (95%CI 0.563 ~ 0.780) (P < 0.05). The change rate of tissue stiffness has a relatively high predictive value for the effect of neoadjuvant chemotherapy in breast cancer.

Normative Cerebral Hemodynamics in Middle-aged and Older Adults Using 4D Flow MRI: Initial Analysis of Vascular Aging.

Background Characterizing cerebrovascular hemodynamics in older adults is important for identifying disease and understanding normal neurovascular aging. Four-dimensional (4D) flow MRI allows for a comprehensive assessment of cerebral hemodynamics in a single acquisition. Purpose To establish reference intracranial blood flow and pulsatility index values in a large cross-sectional sample of middle-aged (45-65 years) and older (>65 years) adults and characterize the effect of age and sex on blood flow and pulsatility. Materials and Methods In this retrospective study, patients aged 45-93 years (cognitively unimpaired) underwent cranial 4D flow MRI between March 2010 and March 2020. Blood flow rates and pulsatility indexes from 13 major arteries and four venous sinuses and total cerebral blood flow were collected. Intraobserver and interobserver reproducibility of flow and pulsatility measures was assessed in 30 patients. Descriptive statistics (mean ± SD) of blood flow and pulsatility were tabulated for the entire group and by age and sex. Multiple linear regression and linear mixed-effects models were used to assess the effect of age and sex on total cerebral blood flow and vessel-specific flow and pulsatility, respectively. Results There were 759 patients (mean age, 65 years ± 8 [SD]; 506 female patients) analyzed. For intra- and interobserver reproducibility, median intraclass correlation coefficients were greater than 0.90 for flow and pulsatility measures across all vessels. Regression coefficients β ± standard error from multiple linear regression showed a 4 mL/min decrease in total cerebral blood flow each year (age β = -3.94 mL/min per year ± 0.44; P < .001). Mixed effects showed a 1 mL/min average annual decrease in blood flow (age β = -0.95 mL/min per year ± 0.16; P < .001) and 0.01 arbitrary unit (au) average annual increase in pulsatility over all vessels (age β = 0.011 au per year ± 0.001; P < .001). No evidence of sex differences was observed for flow (β = -1.60 mL/min per male patient ± 1.77; P = .37), but pulsatility was higher in female patients (sex β = -0.018 au per male patient ± 0.008; P = .02). Conclusion Normal reference values for blood flow and pulsatility obtained using four-dimensional flow MRI showed correlations with age. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Steinman in this issue.

Influence of morphology and hemodynamics on thrombosis in kawasaki disease patients

Kawasaki Disease (KD) patients with co-occurrent coronary artery aneurysms (CAAs) are prone to thrombosis. This study explores the thrombotic influence of morphology and hemodynamics in KD patients with CAAs. Patient-specific computed tomography angiogram images of 9 patients were used to rebuild coronary models (including 23 aneurysms; 10 in thrombosed group, and 13 in non-thrombosed group) and perform computational simulations to obtain the hemodynamic parameters. The thrombosed and non-thrombosed groups were compared in terms of six parameters, namely, the maximum diameter (Dmax), aspect ratio (Rl/d), shape, time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT). The results showed that: (1) In thrombosed aneurysms, there were several vortex structures (eddy zone), of which the position changed continuously in a cardiac cycle. In non-thrombosed aneurysms, the streamlines showed a large streaming zone. (2) Abnormal hemodynamic areas of aneurysms with thrombosis tended to appear in the same region (especially the proximal and near myocardial side of aneurysms). (3) In the non-thrombosed group, there was a correlation between the morphological and hemodynamic parameters. In thrombosed aneurysms, the flow pulsatility has a significant impact on the flow pattern. The thrombosed coronary aneurysms exhibited more risk factors and the co-location of hemodynamic abnormalities was consistent with the position of thrombosis. A score of risk factors could provide the thrombotic information of coronary aneurysms, which might be helpful for long-term clinical management of KD patients.

Multiphysics (Stress and Deformation) Behaviour of Stented Bifurcated Coronary Artery (Soft Tissue) Under Pulsatile Flow Condition

Multiphysics (Stress and Deformation) Behaviour of Stented Bifurcated Coronary Artery (Soft Tissue) Under Pulsatile Flow Condition

A multiscale framework for defining homeostasis in distal vascular trees: applications to the pulmonary circulation.

Pulmonary arteries constitute a low-pressure network of vessels, often characterized as a bifurcating tree with heterogeneous vessel mechanics. Understanding the vascular complexity and establishing homeostasis is important to study diseases such as pulmonary arterial hypertension (PAH). The onset and early progression of PAH can be traced to changes in the morphometry and structure of the distal vasculature. Coupling hemodynamics with vessel wall growth and remodeling (G&R) is crucial for understanding pathology at distal vasculature. Accordingly, the goal of this study is to provide a multiscale modeling framework that embeds the essential features of arterial wall constituents coupled with the hemodynamics within an arterial network characterized by an extension of Murray's law. This framework will be used to establish the homeostatic baseline characteristics of a pulmonary arterial tree, including important parameters such as vessel radius, wall thickness and shear stress. To define the vascular homeostasis and hemodynamics in the tree, we consider two timescales: a cardiac cycle and a longer period of vascular adaptations. An iterative homeostatic optimization, which integrates a metabolic cost function minimization, the stress equilibrium, and hemodynamics, is performed at the slow timescale. In the fast timescale, the pulsatile blood flow dynamics is described by a Womersley's deformable wall analytical solution. Illustrative examples for symmetric and asymmetric trees are presented that provide baseline characteristics for the normal pulmonary arterial vasculature. The results are compared with diverse literature data on morphometry, structure, and mechanics of pulmonary arteries. The developed framework demonstrates a potential for advanced parametric studies and future G&R and hemodynamics modeling of PAH.

Robust flow vector estimation for echocardiography with extended Nyquist velocity using dual-PRF approach: a flow phantom study

To enable quantitative assessments of multi-directional blood flow dynamics such as those in the heart, a two-dimensional (2D) flow vector estimation method using dual-angle Doppler measurements with a sector ultrasound probe was developed. However, that technique was prone to aliasing artifacts because the dual-angle transmissions reduced the pulse repetition frequency (PRF) and Nyquist flow speed by half for each Doppler measurement. To overcome this problem, this study devised a new dual-angle vector flow imaging framework with extended Nyquist velocity using the dual-PRF de-aliasing method. In the proposed framework, the Nyquist flow speed was doubled to 930 mm s−1 compared with the conventional dual-angle approach. Imaging experiments demonstrated that the proposed framework could correct the aliasing artifacts in color Doppler frames and successfully derive 2D flow vectors comparable to particle image velocimetry measurements with a relative error of −14.5% in the fast and 35.2% in the slow flow phases in a pulsatile flow condition.

Impact of turbulence modeling on the simulation of blood flow in aortic coarctation.

Numerical simulations of pulsatile blood flow in an aortic coarctation require the use of turbulence modeling. This paper considers three models from the class of large eddy simulation (LES) models (Smagorinsky, Vreman, -model) and one model from the class of variational multiscale models (residual-based) within a finite element framework. The influence of these models on the estimation of clinically relevant biomarkers used to assess the degree of severity of the pathological condition (pressure difference, secondary flow degree, normalized flow displacement, wall shear stress) is investigated in detail. The simulations show that most methods are consistent in terms of severity indicators such as pressure difference and stenotic velocity. Moreover, using second-order velocity finite elements, different turbulence models might lead to considerably different results concerning other clinically relevant quantities such as wall shear stresses. These differences may be attributed to differences in numerical dissipation introduced by the turbulence models.

MarioHeart: Novel In-Vitro Flow Model for Testing Heart Valve Prostheses and Anticoagulant Therapies.

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.

Structural optimization to improve the dynamic performance of turbine flowmeters

It is of great significance to study the dynamic performance of flowmeters to improve their measurement accuracy in complex working conditions. The dynamic performance of the turbine flowmeter is studied by experiments and numerical simulations under step flow and pulsatile flow conditions. The results suggest that the mass and length of the impeller, the number of blades, the blade angle, and the tip radius of the impeller are the main factors affecting the dynamic performance of the turbine flowmeter. An optimized scheme is proposed based on the analysis results with the feasibility verified by CFD simulations and experiments. The results show that the dynamic performance of the turbine flowmeter is greatly improved after structural optimization. The step response time constant of the optimized model is reduced to 50 % of that of the original model, and the cutoff frequency of the amplitude-frequency characteristic is increased by 87.7 % under pulsatile flow conditions. The overall measurement errors for the pulsatile flow experiments are within 2 %.

Stormwater treatment using an ultrafiltration membrane and pulsatile fluid flow

ABSTRACT A polymeric ultrafiltration (UF) membrane was used for stormwater treatment, with the focus on evaluating the increase in the membrane process productivity by adding pulsatile fluid flow to UF membrane treatment. Sedimentation and sieving were used as pre-treatment. The result showed that increasing the pulse frequency from 0 to 4 Hz increased productivity from −6.6 to 82 LMH. UF membrane removed suspended solids, oil and turbidity below detection limit. The UF membrane also separated total coliforms, E. coli and P. aeruginosa below detection limit. Total organic carbon (TOC) was reduced by between 81%, in average. In addition, the UF membrane was able to reduce BOD7 and COD to below 7 mg/L in the permeate. According to the US EPA, WHO, and national regulations in Canada, Japan, and South Korea, treated stormwater can be used for flushing toilets and streets irrigation and agricultural use.

Prognostic role of pulmonary impedance estimation to predict right ventricular dysfunction in pulmonary hypertension.

The effect of pulmonary hypertension (PH) on right ventricular (RV) afterload is commonly defined by elevation of pulmonary artery (PA) pressure or pulmonary vascular resistance (PVR). In humans however, one-third to half of the hydraulic power in the PA is contained in pulsatile components of flow. Pulmonary impedance (Zc) expresses opposition of the PA to pulsatile blood flow. We evaluate pulmonary Zc relationships according to PH classification using a cardiac magnetic resonance (CMR)/right heart catheterization (RHC) method. Prospective study of 70 clinically indicated patients referred for same-day CMR and RHC [60±16years; 77% females, 16 mPAP <25mmHg (PVR <240dynes.s.cm-5 /mPCWP <15mmHg), 24 pre-capillary (PrecPH), 15 isolated post-capillary (IpcPH), 15 combined pre-capillary/post-capillary (CpcPH)]. CMR provided assessment of PA flow, and RHC, central PA pressure. Pulmonary Zc was expressed as the relationship of PA pressure to flow in the frequency domain (dynes.s.cm-5 ). Baseline demographic characteristics were well matched. There was a significant difference in mPAP (P<0.001), PVR (P=0.001), and pulmonary Zc between mPAP<25mmHg patients and those with PH (mPAP <25mmHg: 47±19 dynes.s.cm-5 ; PrecPH 86±20dynes.s.cm-5 ; IpcPH 66±30dynes.s.cm-5 ; CpcPH 86±39dynes.s.cm-5 ; P=0.05). For all patients with PH, elevated mPAP was found to be associated with raised PVR (P<0.001) but not with pulmonary Zc (P=0.87), except for those with PrecPH (P<0.001). Elevated pulmonary Zc was associated with reduced RVSWI, RVEF, and CO (all P<0.05), whereas PVR and mPAP were not. Raised pulmonary Zc was independent of elevated mPAP in patients with PH and more strongly predictive of maladaptive RV remodelling than PVR and mPAP. Use of this straightforward method to determine pulmonary Zc may help to better characterize pulsatile components of RV afterload in patients with PH than mPAP or PVR alone.

Simultaneous Viscosity Measurement of Suspended Blood and Plasma Separated by an Ultrasonic Transducer

Blood viscosity is influenced by several factors, including red blood cell (RBC) deformability, hematocrit (Hct), and plasma protein levels. To effectively isolate the individual contributions of several factors, it is necessary to simultaneously measure the viscosities of the blood and plasma. In this study, the viscosities of suspended blood and plasma were obtained sequentially by adopting an ultrasonic transducer for plasma separation and a co-flowing microfluidic channel for viscosity measurement. To improve the measurement accuracy of viscosity, the correction factor was obtained through experiments and numerical simulations, which was then inserted into the analytical expression for viscosity. To stabilize the pulsatile blood flow resulting from a micropump, the frequency (f) and voltage (v) were set to f = 300 Hz and v = 140 au, respectively. Flexible polyethylene tubing (i.d. = 500 µm, length = 40 mm) was connected to the microfluidic device as an air damper. Consequently, the coefficient of variance of the blood velocity decreased by up to 1%. As a demonstration, suspended blood (Hct = 20%, 30%, and 40%) was prepared by adding normal RBCs to autologous plasma. Compared with the previous method, the present method overestimates the viscosity values of both the fluids (i.e., suspended blood: 14–25% and plasma: 7–21%). The present method has the ability to sequentially measure the viscosities of suspended blood and plasma. The integrated system contributes to reducing blood-handling procedures (i.e., blood collection, blood loading into the syringe, and syringe installation into the syringe pump).

Axial shear rate: A hemorheological factor for erythrocyte aggregation under Womersley flow in an elastic vessel based on numerical simulation

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.

Specific HIF-2α (Hypoxia-Inducible Factor-2) Inhibitor PT2385 Mitigates Placental Dysfunction In Vitro and in a Rat Model of Preeclampsia (RUPP).

Preeclampsia is one of the leading causes of maternal mortality worldwide and is strongly associated with long-term morbidity in mothers and newborns. Referred to as one of the deep placentation disorders, insufficient remodeling of the spiral arteries during the first trimester remains a major cause of placental dysfunction. Persisting pulsatile uterine blood flow causes abnormal ischemia/reoxygenation phenomenon in the placenta and stabilizes the HIF-2α (hypoxia-inducible factor-2α) in the cytotrophoblasts. HIF-2α signaling impairs trophoblast differentiation and increases sFLT-1 (soluble fms-like tyrosine kinase-1) secretion, which reduces fetal growth and causes maternal symptoms. This study aims to evaluate the benefits of using PT2385-an oral specific HIF-2α inhibitor-to treat severe placental dysfunction. To evaluate its therapeutic potential, PT2385 was first studied in primary human cytotrophoblasts isolated from term placenta and exposed to 2.5% O2 to stabilize HIF-2α. Viability and luciferase assays, RNA sequencing, and immunostaining were used to analyze differentiation and angiogenic factor balance. The ability of PT2385 to mitigate maternal manifestations of preeclampsia was studied in the selective reduced uterine perfusion pressure model performed in Sprague-Dawley rats. In vitro, RNA sequencing analysis and conventional techniques showed that treated cytotrophoblast displayed an enhanced differentiation into syncytiotrophoblasts and normalized angiogenic factor secretion compared with vehicle-treated cells. In the selective reduced uterine perfusion pressure model, PT2385 efficiently decreased sFLT-1 production, thus preventing the onset of hypertension and proteinuria in pregnant dams. These results highlight HIF-2α as a new player in our understanding of placental dysfunction and support the use of PT2385 to treat severe preeclampsia in humans.

Impact of Inclined Magnetic Force on Bio-Fluid in Permeable Bifurcated Arteries: Analytical Approach

The present article aims at presenting analytical solutions of the effects of chemical reaction and inclined magnetic force on blood flow through bifurcated arteries placed in a porous medium in association with heat source. The equations of the blood flow model are solved analytically by means of infinite series solution of convergent scheme with appropriate initial and boundary conditions. The important characteristics of the electromagnetohydrodynamic flow of bio-fluid through bifurcated arteries are distinctly highlighted by virtue of the dual solutions that are obtained for Axial velocity, Normal velocity, fluid Temperature, molar species, Skin-friction, Nusselt Number and Sherwood Number. The behaviour of the biofluid variables with individual parameters like Prandtl Number (Pr), Magnetic drag force (Md), Porosity (Kp), Heat source (Hs), Schmidt Number (Sc), Thermal Radiation (R), Chemical reaction rate (Cr), decay (ξ) are discussed in detail through graphs using MATLAB Software. Validation of this work is presented and found suitable. It is disclosed that the flow of bio-fluid is noticeably influenced by the adequate strength of externally applied inclined magnetic force and porosity. This study is essentially important in simple flow, peristaltic flow, pulsatile flow and drug delivery.

Effect of a bend on vortex formation and evolution in a three-dimensional stenosed geometry during pulsatile flow

Stenosis at arterial bends alters hemodynamics and instigates abnormal disease progression. This configuration is addressed numerically by exploring pulsatile flow (Reynolds number Re = 300–1200; Womersley number Wo = 7.62–15.24) in arteries encountering bend angles of θ = 20°–60°. Individual influences of stenosis and bend on flow dynamics are investigated. Validations against particle image velocimetry experiments for Re = 800 and Wo = 7.62 are carried out in straight and 60° bend stenosed models. For Re = 300–800, the shear layer along the stenosis rolls up into a primary vortex, that is, constrained by the outer wall forming a secondary vortex. At Re = 1200, shear layers undergo instabilities along the post-stenotic region and develop new vortices that promote disturbances and induce asymmetries over the cross-plane flow structures. These features are not present in a straight stenosed tube, showing that the bend is responsible for flow distortion. During the pulsatile cycle, increasing bend angles intensify the size and strength of vortices, while these are suppressed at higher frequencies. A higher bend of 60° experiences large time-averaged wall shear stress and oscillatory loads. In time, wall loading spatially circumscribes the post-stenotic region followed by wall loading during cycle deceleration. These features are consistent with the skewing of a three-dimensional ring structure formed in a stenosed tube that evolves into disintegrated structures in the post-stenotic region. Overall, simulations reveal that strongly bent stenosed arteries experience aggravated oscillatory loading. In the biomedical context, such arterial geometries will require special attention.

High-Frequency Fluctuation Intensity as a Predictor of Post-Stenotic Dilatation in Swine.

To identify the turbulent components of blood flow facilitating aortic lumen dilatation in a post-stenotic dilatation (PSD) porcine model. The porcine abdominal aorta (AA) was moderately coarctated to induce overt flow turbulence in the downstream region and to lead to dilatation in time periods between four and twelve weeks. We propose a new metric, fluctuation intensity (FI), to quantify turbulent fluctuations of pulsatile aortic flow measured within twenty minutes post-coarctation. Lumen perimeter ratio (LPR) of the distal-to-suprarenal AA was used to assess the degree of PSD. Using k-means clustering analysis, we first divided FI frequency spectrum into low- and high-frequency fluctuation intensity (LFFI and HFFI), and subsequently grouped animals with coarctation. Receiver operating characteristic (ROC) analysis was performed to evaluate the ability of the proposed metric to predict PSD. The frequency band of the FI spectrum in facilitating aortic lumen dilatation was identified to be 40∼200 Hz. Using sham group as the reference, pigs receiving coarctation were clustered into two groups with (group A) and without (group B) increases in HFFI values. Coarctation significantly increased LPR values in group A, but not in group B. Moreover, group A exhibited a high probability density distribution on severe elastic fiber fragmentation. ROC analysis indicated HFFI to be capable of predicting PSD with excellent sensitivity and specificity. High-intensity, high-frequency components of blood flow fluctuations induced by moderate coarctation promote elastic lamella degradation and aortic lumen dilatation. HFFI application in flowmeter programs may provide a useful predictor of PSD.

Central arterial stiffness, brain white matter hyperintensity and total brain volume across the adult lifespan.

Mounting evidence suggests that central arterial stiffening is associated with brain ageing in older adults. The purpose of this study was to determine the associations of age with carotid arterial stiffness and carotid-femoral pulse wave velocity (cfPWV), both measurements of central arterial stiffness, the relationship between age-related arterial stiffness, brain white matter hyperintensity (WMH) and total brain volume (TBV), and whether effects of central arterial stiffness on WMH volume and TBV are mediated by pulsatile cerebral blood flow (CBF). One hundred and seventy-eight healthy adults (21-80 years) underwent measurements of central arterial stiffness using tonometry and ultrasonography, WMH and TBV via MRI, and pulsatile CBF at the middle cerebral artery via transcranial Doppler. Advanced age was associated with increases in both carotid arterial stiffness and cfPWV, increases in WMH volume and decreases in TBV (all P < 0.01). Multiple linear regression analysis showed that carotid β-stiffness was positively associated with WMH volume (B = 0.015, P = 0.017) and cfPWV negatively with TBV (B = -0.558, P < 0.001) after adjustment for age, sex and arterial pressure. Pulsatile CBF mediates the associations between carotid β-stiffness and WMH (95% confidence interval: 0.0001-0.0079). These findings suggest that age-related central arterial stiffness is associated with increased WMH volume and decreased TBV, which is likely mediated by increased arterial pulsation.

Effects of a Novel Stereoscopic Flow-Diverting Stent on Intracranial Aneurysm Hemodynamics

Objective: To preliminarily explore the effects of a novel stereoscopic flow-diverting stent on the hemodynamics and pathophysiology of intracranial aneurysm. Methods: Three-dimensional digital subtraction angiography (3D-DSA) and transcranial Doppler ultrasound (TCD) findings and blood examination-related parameters were collected from eligible patients for clinical research. Then a model of aneurysm with its bearing artery was established, based on which a novel stereoscopic flow-diverting stent model was constructed, and hemodynamic data of fluid models with and without novel stereoscopic flow-diverting stent implantation were analyzed. Results: The novel stereoscopic flow-diverting stent could effectively decrease blood flow into the aneurysm and notably reduce blood flow velocity in the aneurysm. The time-averaged wall shear stress (TAWSS) in the aneurysm was distinctly attenuated, and the high shear stress distribution area was also markedly diminished. Conclusion: The novel stereoscopic flow-diverting stent plays an effective isolating role, which is conducive to inducing thrombosis in aneurysm, thus protecting aneurysm vessels. Furthermore, the novel stereoscopic flow-diverting stent can evidently alter the hemodynamic environment in the aneurysm, notably reduce blood flow into the aneurysm, attenuate the mechanical compression of pulsatile blood flow on the vascular wall, and slow down the blood flow velocity in the aneurysm, thus contributing to stabilizing aneurysm. Improving the hemodynamic environment guarantees arterial revascularization and stable thrombosis, thereby effectively controlling the illness.

Surgical treatment of heart failure in China: towards the era of artificial heart

The number of patients with heart failure in China is large, and the proportion of patients with end-stage heart failure continues to increase. The clinical effect of guideline-directed medications therapy for end-stage heart failure is poor. Heart transplantation is the most effective treatment for end-stage heart failure. But it is faced with many limitations such as the shortage of donors. In recent years, the research and development of artificial heart in China has made great progress. Three devices have been approved by the National Medical Products Administration for marketing, and another one is undergoing pre-marketing clinical trial. Since 2017, more than 200 cases of ventricular assist device implantation have been carried out in more than 34 hospitals in China. Among them, 70 patients in Fuwai Hospital, Chinese Academy of Medical Sciences had a 2-year survival rate of 90%. The first patient has survived more than 5 years with the device. More efforts should be put into the training of standardized technical team and quality control. Further research should be carried out in the aspects of pulsatile blood flow pump, fully implanted cable-free device, and improved biomaterial with better blood compatibility.