Maximum Pressure Gradient Research Articles

The hemodynamic and geometric characteristics of carotid artery atherosclerotic plaque formation.

Ischemic stroke, which has a high incidence, disability, and mortality rate, is mainly caused by carotid atherosclerotic plaque. The difference in the geometric structures of the carotid arteries inevitably leads to the variability in the local hemodynamics, which plays a key role in the formation of carotid atherosclerosis. At present, the combined mechanisms of hemodynamic and geometric in the formation of carotid atherosclerotic plaque are not clear. Thus, this study characterized the geometric and hemodynamic characteristics of carotid atherosclerotic plaque formation using four-dimensional (4D) flow magnetic resonance imaging (MRI). Ultimately, 122 carotid arteries from 61 patients were examined in this study. According to the presence of plaques at the bifurcation of the carotid artery on cervical vascular ultrasound (US), carotid arteries were placed into a plaque group (N=69) and nonplaque group (N=53). The ratio of the maximum internal carotid artery (ICA) inner diameter to the maximum common carotid artery (CCA) inner diameter (ICA-CCA diameter ratio), bifurcation angle, and tortuosity were measured using neck three-dimensional time-of-flight magnetic resonance angiography (3D TOF-MRA). Meanwhile, 4D flow MRI was used to obtain the following hemodynamic parameters of the carotid arteries: volume flow rate, velocity, wall shear stress (WSS), and pressure gradient (PG). Independent sample t-tests were used to compare carotid artery geometry and hemodynamic changes between the plaque group and nonplaque group. The ICA-CCA diameter ratio between the plaque group and the nonplaque group was not significantly different (P=0.124), while there were significant differences in the bifurcation angle (P=0.005) and tortuosity (P=0.032). The bifurcation angle of the plaque group was greater than that of the nonplaque group (60.70°±20.75° vs. 49.32°±22.90°), and the tortuosity was smaller than that of the nonplaque group (1.07±0.04 vs. 1.09±0.05). There were no significant differences between the two groups in terms of volume flow rate (P=0.351) and the maximum value of velocity (velocitymax) (P=0.388), but the axial, circumferential, and 3D WSS values were all significantly different, including their mean values (all P values <0.001) and the maximum value of 3D WSS (P<0.001), with the mean axial, circumferential, 3D WSS values, along with the maximum 3D WSS value, being lower in the plaque group. The two groups also differed significantly in terms of maximum PG value (P=0.030) and mean PG value (P=0.026), with these values being greater in the nonplaque group than in the plaque group. A large bifurcation angle and a low tortuosity of the carotid artery are geometric risk factors for plaque formation in this area. Low WSS and low PG values are associated with carotid atherosclerotic plaque formation.

Endoscopic pressure study integrated system using an ultrathin gastroscope for the functional assessment of the lower esophageal sphincter.

The endoscopic pressure study integrated system (EPSIS) represents an innovative approach for evaluating lower esophageal sphincter function by monitoring intragastric pressure using diagnostic gastroscopes. This study aimed to assess the feasibility and validity of employing ultrathin gastroscopes for EPSIS. A retrospective analysis was conducted on a database of consecutive patients who underwent EPSIS using both ultrathin and regular gastroscopes between September 2021 and October 2023. The study compared EPSIS parameters between the two gastroscope types to evaluate the correlation of key metrics. Thirty patients underwent EPSIS with both ultrathin and regular gastroscopes. Significant positive correlations were observed in the pressure waveform: maximum intragastric pressure (mmHg) (ρ = 0.82, P < 0.001) and intragastric pressure gradient (mmHg/s) (ρ = 0.80, P < 0.001) when comparing the two gastroscopes. Maximum intragastric pressure (15.5 [5.3-20.3] vs. 18.5 [3.4-21.6], P < 0.001) and pressure gradient (0.16 [0.013-0.41] vs. 0.24 [0.0039-1.13], P < 0.001), (median [range]) were significantly lower with ultrathin gastroscopes. This study establishes that EPSIS parameters obtained with an ultrathin gastroscope exhibit a significant correlation with those obtained using a regular gastroscope, with each EPSIS parameter consistently lower. These findings support the viability of EPSIS for ultrathin gastroscopy and highlight its potential as a diagnostic tool for assessing lower esophageal sphincter function.

A method for automated masking and plantar pressure analysis using segmented computed tomography scans

BackgroundPlantar pressure, a common gait and foot biomechanics measurement, is typically analyzed using proprietary commercial software packages. Regional plantar pressure analysis is often reported in terms of underlying bony geometry, and recent advances in image processing and accessibility have made computed tomography, radiographs, magnetic resonance imaging, or other imaging methods more popular for incorporating bone analyses in biomechanics. Research QuestionCan a computed tomography-based regional mask provide comparable regional analysis to commercial plantar pressure software and can the increased flexibility of an in-house method obtain additional insight from common measurements? MethodsA plantar pressure analysis method was developed based on bony geometry from computed tomography scans to calculate peak pressure, pressure time integral incorporating sub-peak values, force time integral, pressure gradient, and pressure gradient angle. Static and dynamic plantar pressure were acquired for 4 subjects (male, 65 ± 2.4 years). Plantar pressure variables were calculated using commercial and computed tomography-based systems. ResultsDynamic peak pressure, pressure time integral, and force-time integral computed using the bone-based software was 5 % (9kPa), 7 % (0.3kPa-s) and 13 % (0.3 N-s) different than the commercial software on average. Region masks of the metatarsals and toes differed between commercial and computed tomography-based software due to subject-specific bone geometry and toe shape. Pressure time integral values incorporating sub-peak pressure were higher and demonstrated higher relative hindfoot values compared to those without. Removing step-on frames to static pressure analysis decreased forefoot pressures. Regional maps of peak pressure and maximum pressure gradient demonstrate different peak locations. SignificanceComputed tomography-based regional masks are comparable to commercial masks. Inclusion of static step-on frames and sub-peak pressures may change regional plantar pressure patterns. Differences in location of maximum pressure gradient and peak pressure may be useful for assessing subject specific injury risk.

Correlation between pressure gradient from echocardiography and peak-to-peak pressure gradient from cardiac catheterization or surgery in patients with coarctation of aorta.

The gold standard for assessing pressure gradients (PG) across coarctation involves measurements obtained through cardiac catheterization or surgical intervention. There has been ongoing discussion regarding the accuracy of non-invasive methods for estimating these gradients. This study sought to establish the correlation and agreement between the systolic blood pressure (SBP) gradient between the upper and lower extremities, as well as, the mean and maximum PG derived from echocardiography, in comparison to the peak-to-peak pressure gradient obtained from either cardiac catheterization or surgery. We conducted a retrospective study on patients < 18 years diagnosed with coarctation at Chiang Mai University Hospital from 2011 to 2022. The study involved the measurement of the SBP gradient between the upper and lower extremities, mean and maximum PG using echocardiography, peak-to-peak pressure gradient obtained from cardiac catheterization, and pressure gradient recorded during surgical procedures. The Spearman's correlation and Bland-Altman analysis were employed to assess correlation and agreement. Fifty-four patients with aortic coarctation were enrolled. The mean PG measured by echocardiography showed a significantly moderate correlation (r = 0.78, p < 0.001) and the highest level of agreement according to Bland Altman plots, in comparison to the peak-to-peak pressure gradient measured during both cardiac catheterization and surgical procedure. The max PG demonstrated a notable overestimation compared to the gold standard (mean difference + 13.14 with a slope of biases + 0.64, p < 0.001). The mean PG obtained through echocardiography has more potential to be applied in practical application in predicting pressure gradient in patients with coarctation.

Alleviation of micro-pressure waves radiated from tunnel hoods

When a train enters a tunnel, an impulsive pressure wave, called a micro-pressure wave (MPW), radiates from the tunnel exit. The MPW causes infrasound and audible noise near the tunnel portals; therefore, it should be reduced for environmental reasons. A typical countermeasure is the installation of a hood at the tunnel entrance portal. In a previous study, we proposed a new type of hood that combined two hoods with constant and different cross-sectional areas (a two-step hood). The two-step hood was more effective than the existing hoods. However, because the cross-sectional area of the portal of the two-step hood was larger than that of the existing hoods, the MPW radiated by a train entering the opposite tunnel portal increased in a double-track tunnel. This study developed a new concept for a tunnel hood that reduces the radiated MPW (performance at the MPW radiation stage) while maintaining the performance in terms of reducing the maximum pressure gradient of the compression wave (CW) generated by a train entering a tunnel (performance at the CW generation stage). The desired specifications for satisfying both performances were determined through calculations based on acoustic theory, and their performances were investigated through model experiments using a train model launcher. As the results, the desired specifications were lh3/lw>0.6, lh1≈lh2>lwMt/1-Mt, σh1=1.4, and σh2=2.5, where lh1, lh2, and lh3 are lengths of first hood, second hood, and added lateral wall, respectively, lw is wavefront thickness, Mt is the train’s Mach number, and σh1 and σh2 are the cross-sectional area ratio of the first and second hoods to tunnel, respectively. The developed hood is expected to provide more effective performance in mitigating MPW than existing hoods.

Multi-spatial scale and multi-frequency resolution Proper Orthogonal Decomposition for patterns of wall-streamwise pressure gradient fluctuation of impinging jets

In the coating industry, seemingly ordered millimeter-scale W or X-like patterns inevitably appear on the coating wiped by jets. Considering the dynamic control of coating thickness by the maximum wall-streamwise pressure gradient on the impinging wall, exploring its fluctuation characteristics may provide insights into W or X-like patterns formation and suppression. Large Eddy Simulation is conducted to simulate jets impinging on a dry wall. The computed pressure gradient is processed by a two-dimensional Discrete Wavelet Transform using Coif2 wavelet, helping determine the spatial scale dominated by its fluctuation energy and providing snapshots on specific spatial scales. Afterward, snapshots on selected spatial scales undergo processing using either multi-scale Proper Orthogonal Decomposition (mPOD) or spectral POD, depending on the presence of some distinguishable peaks in its spectrum. This process can extract modes with spectral purity on the corresponding spatial scale, providing an advantage in addressing problems strongly linked to spatial scales. Applying this methodology, the study unveiled the evolution of the pressure gradient modes with frequency on the energy-dominant spatial scale, ranging from 0.625 mm × 0.785 mm to 1.25 mm × 1.57 mm. This evolution may be the cause of W or X-like patterns and suggests introducing a guiding jet to mitigate them.

Associations between vitamin D status, VDR gene polymorphisms and echocardiographic markers in Polish patients with cardiovascular disease.

Aim: This work was designed to investigate the associations between vitamin D metabolites, VDR gene polymorphismsand echocardiographic markers in a population of patients with cardiovascular disease. Methods: Echocardiographic markers for 42 patients were determined with tissue Doppler techniques. PCR-restriction fragment length polymorphismanalysisidentified genetic variants ApaI, TaqI, BsmI and FokI. A validated UHPLC-MS/MS methoddetermined vitamin D metabolites. Results: Patients with the ApaI-GT genotype exhibited a lower pressure gradient across the aortic valve than ApaI-TT carriers. BMI, ApaI-GT, TaqI-TC, aortic arch diameterand maximal pressure gradient were significant univariate predictors of hypertension. Conclusion: A potential link existsbetween VDR gene polymorphisms and cardiovascular function.

Методология влияния свободной порозности и водоотдачи на процессы, происходящие в почвогрунтах оросительных каналов с земляным руслом

Purpose of the research: to consider the influence of free porosity and water loss on the filtration of water from channels with an earthen bed. Explore existing calculation methods taking into account the parameters of free porosity and fluid loss. Collect calculation material that can form the basis of a program for calculating the filtration of channels with an earthen bed, taking into account the factors influencing the first and second stages of filtration in the channels. Materials and research methods: The work used theoretical methods for calculating filtration in channels with an earthen bed, presented the calculation of the loss of flow rate Qf for filtration per 1 km of length with a steady free surface for different types of channel cross-sections, considered the basic formulas proving that water supply changes with changes in transverse cross-section of the canal, the change in the stability of the canal slopes is shown, a test calculation of the canal for filtration strength according to the maximum pressure gradients is presented, the need to compare the excess of the critical filtration pressure gradient with the permissible pressure gradient is considered. Results and its discussion. The relationship between the total, capillary and minimum moisture capacity and water yield in the thickness of soils is presented, the dependence of free porosity on the groundwater level, and the change in water permeability of soils over time are considered. As a result of the research, material was collected on the influence of free porosity and water loss on the movement of water in soils and the influence on the increase in groundwater levels in the zone of influence of canals, a methodology was presented for the influence of free porosity and water loss on the processes occurring in the soils of irrigation canals in an earthen channel, which will allow its use for modeling these processes on a computer.

CO2 soluble surfactants for carbon storage in carbonate saline aquifers with achievable injectivity: Implications from the continuous CO2 injection study

Continuous CO2 injection (CCI) into saline aquifers suffers from low sweep efficiency. While utilizing foam can effectively address this issue, a relatively potent foam design may undesirably reduce the injectivity of CO2. In this study, the potential of CO2-soluble surfactants assisted carbon storage in carbonate saline aquifers was evaluated by core flooding tests and numerical simulations. It is found that foam can be generated at the displacement front during continuous CO2 injection with 0.39 g/L surfactant (CCI + S, fg = 100 %). The CO2 saturation can reach 60 % after 1.0 pore volume of CCI + S, approximately 50 % higher than that of CCI. The maximum pressure gradient is around 1.5 psi/ft at an injection rate of 1.0 ft/d in 162 mD Indiana Limestone for CCI + S. The effects of surfactant concentration, foam quality, and rock permeability were also investigated by core flooding. Moreover, the influence of surfactant partitioning and adsorption on CO2 transport behavior was systematically evaluated by numerical simulation in synthetic and geological models, using modeling parameters that are realistic for field applications. The advantage of injecting surfactant with CO2 is more evident in heterogeneous saline aquifers. Such novel injection strategy provides a promising approach for carbon sequestration in saline aquifers by controlling the mobility of CO2 at the displacement front and simultaneously maintaining acceptable injectivity in the field. The CCI + S process may also impose less risk to the caprock. Expanding the potential CO2 storage sites to heterogeneous saline aquifers could be a game-changer. Our understanding of foam dynamics in porous media could also be advanced.

Permeability reduction techniques: Plain and fiber HPAM gels in fractured cores

The aim of this study is to investigate how fibers influence the ability of polymer gels to resist washing out from fractures. For this purpose, synthetic and mineral wool fibers were integrated into polymer gels. These fiber-gels were compared to plain gels using bottle tests, viscosity measurements, and fractured core flooding experiments.The bottle tests show no effect of 13-mm-long synthetic fibers on gel strength. However, inside a constricted fracture, the polymer-synthetic fiber gel exhibited 8.4 times higher resistance to the flow of brine compared to the plain gel. This is explained by the retention of the fibers at the constriction point. In low salinity brine, mineral wool fibers allowed a substantial improvement in gel strength, while, at the same time, a reduction in the concentration of chemicals by 40% was made possible.Furthermore, with the addition of 0.6 wt.% mineral wool fibers, the viscosity of the 0.3 wt.% polymer gel increased from 560.5 to 106,920 cp. In fact, in a 1-mm-wide fracture, a gel containing 0.3 wt.% polymer and 0.6 wt.% mineral wool fiber achieved a post-flush pressure gradient that was 58 times higher than a 0.75 wt.% plain polymer gel. Unfortunately, the choice of a makeup brine with an increased salinity resulted in the deterioration of fiber-gel strength. Nonetheless, a substantial improvement of gel strength can be achieved by adding 0.6 wt.% mineral wool fibers, even if the salinity is as high as 143 g/L. Moreover, in experiments in which the permeability of the adjacent matrix was very low, 0.018 mD, a gel of 0.3 wt.% polymer and 0.6 wt.% mineral wool fiber prepared in 242.6 g/L brine, was still superior to a 0.75 wt.% plain gel prepared in low salinity brine.Experimentation with large fracture widths of 2.55 mm and 4 mm was also done to confirm gel effectiveness. For example, a gel of 0.3 wt.% polymer and 0.6 wt.% mineral wool fiber, prepared in 14 g/L brine, provided a 1.46 times higher post-flush pressure gradient in a 2.55-mm-wide fracture, as compared to that of a 0.75 wt.% plain polymer low salinity gel in a 1-mm-wide fracture. With an increase in the salinity, to 234.6 g/L, of the makeup brine used with a fiber-gel, the resistance to the flow of brine in a 2.55-mm-wide fracture became comparable to that of a plain gel in a 1-mm-wide fracture. In a 4-mm-wide fracture, a gel with 0.3 wt.% polymer prepared in 234.6 g/L brine and one of 0.5 wt.% polymer prepared in 14 g/L brine, each with 0.6 wt.% mineral wool fiber, provided maximal post-flush pressure gradients equal to 12–14 psi/ft. This is the same range usually expected from a 0.5 wt.% relatively low molecular weight plain polymer gel in a 1-mm-wide fracture.Although, fibers improved the ability of gels to resist washing out from fractures, in a 4-mm-wide fracture such a fiber-gel could not provide notable resistance to the flow of brine with an increase in the superficial flow velocity higher than 1,000 ft/d. Discovering formulas that would increase the resistance of gels to being washed out of wide fractures must continue.

Von Willebrand factor Ristocetin co-factor activity to von Willebrand factor antigen level ratio for diagnosis of acquired von Willebrand syndrome caused by aortic stenosis

BackgroundSevere aortic stenosis (AS) causes acquired von Willebrand syndrome by the excessive shear stress–dependent cleavage of high molecular weight multimers of von Willebrand factor (VWF). While the current standard diagnostic method is so-called VWF multimer analysis that is western blotting under nonreducing conditions, it remains unclear whether a ratio of VWF Ristocetin co-factor activity (VWF:RCo) to VWF antigen levels (VWF:Ag) of <0.7, which can be measured with an automated coagulation analyzer in clinical laboratories and is used for the diagnosis of hereditary von Willebrand disease. ObjectivesTo evaluated whether the VWF:RCo/VWF:Ag is useful for the diagnosis of AS-induced acquired von Willebrand syndrome. MethodsVWF:RCo and VWF:Ag were evaluated with the VWF large multimer index as a reference, which represents the percentage of a patient’s VWF high molecular weight multimer ratio to that of standard plasma in the VWF multimer analysis. ResultsWe analyzed 382 patients with AS having transaortic valve maximal pressure gradients of >30 mmHg, 27 patients with peripheral artery disease, and 46 control patients free of cardiovascular disease with osteoarthritis, diabetes, and so on. We assumed a large multimer index of <80% as loss of VWF large multimers since 59.0% of patients with severe AS had the indices of <80%, while no control patients or patients with peripheral artery disease, except for 2 patients, exhibited the indices of <80%. The VWF:RCo/VWF:Ag ratios, measured using an automated blood coagulation analyzer, were correlated with the indices (rs = 0.470, P < .001). When the ratio of <0.7 was used as a cut-off point, the sensitivity and specificity to VWF large multimer indices of <80% were 0.437 and 0.826, respectively. ConclusionVWF:RCo/VWF:Ag ratios of <0.7 may indicate loss of VWF large multimers with high specificity, but low sensitivity. VWF:RCo/VWF:Ag ratios in patients with AS having a ratio of <0.7 may be useful for monitoring the loss of VWF large multimers during their clinical courses.

A Wellbore Pressure Control Method for Two-Layer Coal Seam Gas Coproduction Wells

In coal seam gas (CSG) coproduction wells, due to the different production pressures of CSG production layer at different depths, the interlayer interference in wellbore seriously affects the gas production of a coproduction well. To effectively suppress the interlayer interference of the wellbore, a wellbore pressure distribution method for a two-layer coproduction well is proposed. Based on the analysis of the factors influencing the flow pressure distribution in the wellbore of two-layer coproduction wells, a method of coproduction flow pressure adjustment by regulating the wellhead pressure and the depth of the dynamic fluid level was established in this paper. The results show that wellhead pressure can directly affect the production pressure of two layers. The variation in layer 1 output mainly affects the pressure difference between the wellhead pressure and the pressure at the depth of layer 1, which has little effect on the pressure difference between layer 1 and 2. An increase in gas production from layer 2 would not only cause a pressure increase in layer 1, but also result in a reduction of the production pressure at layer 2. The maximum pressure gradient of the gas section is 0.14 MPa/100 m, and the pressure gradient of the gas–liquid section is 0.53–1.0 MPa/100 m.

Impact of Premature Ventricular Complex (PVC) Burden on the Left Ventricle in the Structurally Normal Heart: Hemodynamic Alterations of Idiopathic PVC on Echocardiography.

Premature ventricular complex (PVC) without structural heart disease is mostly viewed as a benign arrhythmia. However, the high burden of PVC causes cardiomyopathy due to intraventricular dyssynchrony. The effects of ectopic contraction on left ventricular (LV) hemodynamics in the structurally normal heart are unclear. To examine the effect of PVC burden on LV dimension, LV systolic function, and intraventricular blood flow, and to determine whether ectopic ventricular contraction affects LV hemodynamics. Patients aged ≥ 18 years with PVC ≥ 5% on Holter recording were enrolled and divided into groups G1 (5-10%), G2 (10-20%), and G3 (≥ 20%). We excluded patients with structural heart diseases, pacemakers, and LV systolic dysfunction [LV ejection fraction (LVEF) < 50%]. Clinical characteristics and routine transthoracic echocardiography parameters were compared. The end-systolic LV internal dimension increased according to the PVC burden from G1 to G3 (p = 0.001). LVEF was inversely associated with PVC burden from G1 to G3 (p = 0.002). The same pattern was seen for LV outflow tract (LVOT) maximal velocity (p = 0.005) and maximal pressure gradient (PG) (p = 0.005), LVOT velocity time integral (VTI) (p = 0.03) and LV stroke volume index (LVSI) (p = 0.008). Systolic function and LV end-systolic dimension were inversely associated with PVC burden. Decreased LVOT flow velocity and PG were related to increased PVC burden. LVOT VTI and LVSI were smaller when the PVC burden exceeded 20%. These negative hemodynamic manifestations of idiopathic PVC were considerable even in structure normal hearts, hence the early elimination of PVC is strongly advised.

Microbubble contrast agent as a minimally invasive pressure sensor at body temperature and reduced concentrations in an ultrasound flow phantom

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): MRC. Background Cardiac catheterisation is the gold standard for assessing cardiac pressures. However, this is an invasive and costly procedure. A minimally invasive alternative may be to use the subharmonic signal of microbubble ultrasound contrast agents to estimate pressure using echocardiography (Sub-Harmonic Assisted Pressure Estimation: SHAPE). Purpose The aim of this work was to investigate the ability of SHAPE to track dynamic diastolic pressures in a flow phantom at body temperature and at reduced microbubble concentrations. Methods A priming dose of 0.4 mL/L of sulphur hexafluoride microbubbles was circulated through a silicone tube using a peristaltic pump at a flow rate of 375 mL/min (generating 376 pressure cycles/min and maximum pressure gradient of 1.9 mmHg/ms; Fig. 1). The ULtrasound Advanced Open Platform (ULA-OP) was used with a cardiac phased array transducer to transmit a pulse-inversion sequence at 2.1 MHz. Radiofrequency data were recorded at five acoustic pressures (71–228 kPa peak-negative). To investigate the effects of temperature, the subharmonic-pressure relationship was measured over 60 min at both room and body temperature (37°C). Microbubble concentration was maintained by regular top-up (0.15 mL/L every 3–5 min). To investigate the effect of lower concentrations on the subharmonic-pressure relationship, a priming dose of 0.4, 0.3 or 0.2 mL/L was administered before a single acquisition was made. The system was immediately purged before testing the next concentration. The subharmonic (1.05 MHz) amplitude of the microbubbles was calculated over a 40% bandwidth. A solid-state catheter recorded ground-truth pressures. Correlation coefficient (r) and sensitivity (dB/mmHg) of the subharmonic signal to the pressure values were calculated. Results The mean correlation coefficient (r = 0.91 ± 0.04; Fig. 2) and sensitivity (0.20 ± 0.04 dB/mmHg) at body temperature (n = 20) were significantly greater than those for the same batch of microbubbles at room temperature (r = 0.81 ± 0.07 and 0.14 ± 0.02; n = 18; p &amp;lt; 0.05) at the optimal acoustic pressure (Fig. 2). No significant differences in the subharmonic-pressure relationship were observed between the three different microbubble concentrations (Correlation: r = 0.96 ± 0.00, 0.96 ± 0.01, 0.97 ± 0.01. Sensitivity: 0.26 ± 0.02, 0.26 ± 0.03, 0.28 ± 0.02 mmHg/dB for 0.4, 0.3 and 0.2 mL/L, respectively; n = 3) at the optimal acoustic pressure. Conclusions SHAPE can accurately track diastolic pressures five times faster than the average resting heart rate at body temperature and with reduced microbubble concentrations. SHAPE is a potential method for assessing cardiac diastolic pressures using ultrasound in a minimally invasive fashion, being suitable for use in patients with faster microbubble clearance or in the event of delayed acquisition. The use of SHAPE fits into routine clinical procedures and has the potential to improve the diagnosis and monitoring of cardiovascular diseases.

Influence of factors on filtration regime of an earth dam under headwater drawdown

Introduction. As the statistics of observations of groundwater retaining structures shows, one of the most significant factors of emergencies in these structures is the occurrence of filtration deformations in the dam body. This often results in the appearance of moves of concentrated filtration. The occurrence of these phenomena can be provoked by a rapid decrease of the headwater level known as reservoir drawdown. It can be caused either by the technological requirements of the operation of the hydraulic unit or by the occurrence of an emergency situation. Modern design standards require mandatory consideration of the case of rapid drawdown with an assessment of the filtration regime and stability of the structure.&#x0D; &#x0D; Materials and methods. The results of numerical studies of unsteady filtration in a homogeneous earth dam under reservoir drawdown are considered. Numerical studies were carried out on the basis of the finite element method using the PRAXIS software package. Test calculations were carried out, which showed the reliability of the results obtained. The influence of the soil filtration coefficient of the dam, the rate of drawdown and the slope of the structure on the change in the position of the depression curve and the value of the maximum pressure gradient is analyzed.&#x0D; &#x0D; Results. For the considered variants of earth dams with different characteristics, the parameters of the filtration flow are obtained when the headwater level changes: the position of the depression curve and the values of the maximum pressure gradients. An assessment of the possibility of occurrence of filtration deformations of soils of the upper prism of the dam is given.&#x0D; &#x0D; Conclusions. The use of the PLAXIS software package for solving problems of unsteady filtration under reservoir level changes allows to obtain reliable results that are well comparable with the results of other proven methods. At certain rates of runoff for soils of different permeability in the upper prism of an earth dam, large values of pressure gradients exceeding critical values may occur. This indicates the necessity to control the process of drawdown and the use of antifiltration measures.

&lt;b&gt;Reducing Micro-pressure Waves Using Train Nose Optimization Based on Linear Acoustic Theory&lt;/b&gt;

The shapes of train noses have been optimized for several decades to reduce the peak values of the micro-pressure waves radiating from tunnel portals of high-speed railways. This study optimized the shapes of multistep noses using three transfer functions based on the theory of compact Green's function (WT ), experimental results (WE ), and the average value of WT and WE (WM ). Model experiments were performed to measure the maximum pressure gradients of compression waves generated by each train nose entering a tunnel for offset running. For optimized train noses based on WT or WE , the values of the maximum pressure gradient could not be sufficiently reduced, and the pressure gradient waveforms were not trapezoidal. Although the optimized noses based on WM reduced the maximum pressure gradients considerably, the maximum pressure gradient values were larger than those for the optimized noses based on the computational fluid dynamics.

Creating the Phenotype of Preeclamptic Endothelial Dysfunction in Placental Vessels

Objective: To determine if placental vessel endothelial dysfunction can be produced in control vessels by exposure to preeclamptic plasma, establishing a model to further explore the mechanisms of dysfunction and therapeutics to restore function in preeclampsia. Hypothesis: Preeclamptic plasma administered to unaffected vessels induces endothelial dysfunction. Methods: Placental microvessels were dissected from the maternal side of placentas from patients consented to the Medical College of Wisconsin Maternal Research Placenta and Cord Blood Bank. Control vessels were treated with 10% healthy maternal plasma or 10% preeclamptic (PreE) maternal plasma within the vessel lumen for 12-16 hours[MJ1]. PreE vessels were not treated with plasma. Microvessels were then cannulated on glass micropipettes, pressurized to 60mmHg and constricted with 0.1-1.0 nM Endothelin-1 (ET-1). A 1-100cm H2O pressure gradient was applied and the inner diameter of the vessel was measured by video microscopy. The change in diameter was calculated as a % of maximum diameter as assessed by exposure to 100μM papaverine. Flow mediated dilation (FMD) was evaluated by a two-way ANOVA test with Dunnett’s multiple comparisons. The maximum dilation values were evaluated by a Kruskal-Wallis test with Dunn’s multiple comparative test or t-test as appropriate. FMD is evaluated as mean +/- SEM. Data: Control vessels at maximum flow dilated to 81.1 % ± 7.1 % (n=5), whereas vessel from PreE placentas dilated to 36.9 % ± 8.6% (n=3,). Incubation of control vessels with normal plasma resulted in maximal dilation of 80.6% ± 3.3%, n=3. Control vessels incubated with plasma from PreE patients dilated to 44.7% ± 4.7%. n=3). Summary of Results: Control vessels dilated significantly more than PreE vessels when evaluated by t-test (p=0.05). Incubation of control vessels with normal plasma did not change maximal dilation (p&gt;0.99). Control vessels incubated with PreE plasma demonstrated a near significant drop in dilatory capacity (p=0.05). PreE plasma exposed vessels compared to untreated PreE vessels showed no significant difference (p=0.46[DDG2] ).When comparing overall flow mediated dilatory responses in these vessels there is a significant difference observed between control vessels, control vessels treated with PreE plasma, and PreE vessels at 50cm H2O (p&lt;0.05). This difference is even more significant (p&lt;0.01) at the maximum pressure gradient when analyzed by two-way ANOVA. There is no significant difference at any point between control vessels and control vessels treated with normal plasma as evaluated by two-way ANOVA (p&gt;0.99). Conclusions: The addition of PreE plasma to control vessels demonstrates similar impairment in endothelium-dependent vasodilation as seen in untreated PreE vessels. Future directions will include evaluation of the mechanisms of vasodilation and therapeutic options that could restore endothelial function in PreE vessels. NHLBI 1K08HL150340-01 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Left ventricular remodeling and long-term outcomes of aortic stenosis patients receiving 19mm Mosaic.

Mosaic valve shows higher pressure gradient after aortic valve replacement compared to other same size labeled prostheses in postoperative echocardiogram. The purpose of this study was to evaluate the mid-term echocardiogram findings and long-term clinical outcomes of patients receiving a 19mm Mosaic. Forty-six aortic stenosis patients receiving 19mm Mosaic and 112 patients receiving either 19mm Magna or Inspiris, who underwent mid-term follow-up echocardiogram were included in the study. Mid-term hemodynamic measurements evaluated by trans-thoracic echocardiogram and long-term outcomes were compared. Patients receiving Mosaic were significantly older (Mosaic: 76 ± 5.1years vs. Magna/Inspiris: 74 ± 5.5years, p = 0.046) and had smaller body surface area (Mosaic: 1.40 ± 0.114m2 vs. Magna/Inspiris: 1.48 ± 0.143m2, p < 0.001). There were no significant differences in comorbidities and medications. Post-operative echocardiogram performed at 1week after the surgery showed higher maximum pressure gradient in patients receiving Mosaic (Mosaic: 38 ± 13.5mmHg vs. Magna/Inspiris: 31 ± 10.7mmHg, p = 0.002). Furthermore, mid-term echocardiogram follow-up performed at median duration of 53 ± 14.9months after the surgery continuously showed higher maximum pressure gradient in patients receiving Mosaic (Mosaic: 45 ± 15.6mmHg vs. Magna/Inspiris: 32 ± 13.0mmHg, p < 0.001). However, there were no significant difference in changes in left ventricular mass from baseline in both groups. Kaplan-Meyer curve also showed no difference in long-term mortality and major adverse cardiac and cerebrovascular event between the two groups. Although the pressure gradient across the valve evaluated by echocardiogram was higher in 19mm Mosaic compared to 19mm Magna/Inspiris, there were no significant differences in left ventricular remodeling and long-term outcomes between the two groups.

Emergent transcatheter aortic valve implantation combined with enterectomy for acute decompensated heart failure caused by severe aortic stenosis and strangulated femoral hernia.

A 74-year-old female was admitted to our department with orthopnea, oliguria, and vomiting. She had a pacemaker implanted two years ago. Physical examination revealed an 8 cm × 6 cm bulge in the right groin. The transthoracic echocardiography showed that the area of aortic orifice was 0.4 cm2 and the left ventricle ejection fraction (LVEF) was 25%. The Society of Thoracic Surgeons score was 25.6%. Abdominal ultrasound demonstrated right femoral hernia with intestinal obstruction. Because of hemodynamic instability and the risk of intestinal necrosis, emergent transcatheter aortic valve implantation (TAVI) combined with hernia repair was scheduled to perform. The procedure was performed under general anesthesia with intubation. The transesophageal echocardiography (TEE) showed that the maximal and mean pressure gradient was 64 and 35 mmHg, respectively (Panels A–C); coronary angiography indicated no coronary artery stenosis. We chose left femoral artery access for TAVI through a totally percutaneous approach. According to TEE, aortic root angiography and based on the balloon pre-dilation (Panel D), 26 Venus-A self-expandable valve was successfully implanted (Panel F). And then, the right oblique cutdown was performed, and a tense hernial sac was revealed, in which we observed an 8-cm-long necrotic bowel (Panel E). The gastrointestinal surgeon had to resect the strangulated and anastomose the normal bowel. TEE showed that the maximal and mean aortic pressure gradient was 13 and 7 mmHg, respectively (Panels G and H). Thirteen days later after the operation, the patient was discharged from the hospital with no complications. Follow-up echocardiography demonstrated that the device position was appropriate, no perivalvular leakage, and the LVEF increased to 50%.

Integrative echocardiographic assessment of post-operative obstruction severity and restenosis after balloon valvuloplasty in 81 dogs with pulmonary stenosis

Introduction/objectivesPulmonary stenosis (PS) is a congenital defect in the dog that is managed with balloon valvuloplasty (BV). Obstruction severity is routinely assessed using transthoracic echocardiography. The objectives of this study were to describe the short-term changes and long-term restenosis by retrospectively evaluating flow-dependent and flow-independent echocardiographic variables for dogs with PS after BV. Animals, materials, and methodsMedical records and stored echocardiographic images were reviewed from dogs that received BV for PS. The following echocardiographic variables were measured or calculated: maximum systolic ejection velocity (VmaxPV) and velocity-derived maximal pressure gradient (PV maxPG) across the pulmonary valve; ratio of aortic to pulmonary velocity time integral (VTIAV/VTIPV); ratio of aortic to pulmonary maximal velocity. ResultsEighty-one dogs with PS that had a BV were included. Each of these dogs had pulmonary obstruction severity assessed in at least three timepoints. Forty-nine dogs had at least one additional examination performed, the last of which occurred a median of 504 days after the BV. Echocardiographic variables at the first follow-up had increased by a clinically relevant quantity in 20–34% of the dogs when comparing to the immediate post-BV examination. The last follow-up examination identified valve restenosis in 18–38% of the dogs in this study. Valve type and pre-BV obstruction severity did not have a significant effect (P > 0.1). ConclusionsFor the assessment of BV efficacy, the immediate post-BV echocardiogram may not be as useful as the first follow-up examination several months later. Pulmonary restenosis after BV may be more prevalent than previously reported.