Jet Velocity Research Articles

Abstract 4119560: Oxidized Phospholipids and Calcific Aortic Valvular Disease

Introduction: Oxidized phospholipids (OxPL) are carried by apolipoprotein B-100-containing lipoproteins (OxPL-apoB) including lipoprotein(a) [Lp(a)]. Both OxPL-apoB and Lp(a) have been associated with calcific aortic valve disease (CAVD). Aims: We aimed to evaluate the independent associations between OxPL-apoB, Lp(a) and the prevalence, incidence, and progression of CAVD. Methods: OxPL-apoB and Lp(a) were evaluated in the Multi-Ethnic Study of Atherosclerosis (MESA) and a participant-level meta-analysis of four randomized trials of participants with established aortic stenosis (AS). In MESA, the association of OxPL-apoB and Lp(a) with aortic valve calcium (AVC) at baseline and 9.5 years was evaluated using multivariable ordinal regression models. In the meta-analysis, the association between OxPL-apoB and Lp(a) with AS progression (annualized change in peak aortic valve jet velocity (V max )) was evaluated using multivariable linear regression models. Results: In MESA, both OxPL-apoB and Lp(a) were independently associated with prevalent AVC (OR (95% CI) per SD: 1.19 (1.07-1.32) and 1.13 (1.01-1.27), respectively) with a significant interaction between the two (p<0.01). Both OxPL-apoB and Lp(a) were associated with incident AVC at 9.5 years when evaluated independently (interaction p<0.01). The OxPL-apoB*Lp(a) interaction demonstrated higher odds of prevalent and incident AVC for OxPL-apoB with increasing Lp(a) levels. Mediation analyses demonstrated that Lp(a) partially mediated the association between OxPL-apoB and AVC. In a 2x2 analysis, the greatest risk for both prevalent and incident AVC was observed when Lp(a) and OxPL-apoB were both above the 80 th percentile ( Figure ). In the meta-analysis, when analyzed separately, both OxPL-apoB and Lp(a) were independently associated with faster increase in V max , but when evaluated together, only OxPL-apoB remained significant (ß 0.07, 95% CI 0.01-0.12, Figure ). Conclusions: OxPL-apoB is an independent predictor of the presence, incidence and progression of AVC and established AS, particularly in the setting of elevated Lp(a) levels and may represent a novel therapeutic target for CAVD.

Transient Sand Scour Dynamics Induced by Pulsed Submerged Water Jets: Simulation Analysis

Water jet scouring technology is extensively applied in marine engineering, harbor maintenance, river training, and various other fields, showcasing a broad spectrum of potential applications. However, achieving a comprehensive understanding of the transient sand scouring characteristics of water jets remains challenging due to the inherent complexity of the coupled flow structure involving submerged jets and environmental fluids, along with the intricate dynamics of two-phase flow. This study, rooted in numerical simulation and experimental validation, introduces pulse characteristics into a submerged jet. A thorough investigation is conducted to explore the transient sand scouring characteristics and sand transport laws of the submerged jet under diverse working conditions. The results of this study revealed that the main reason for the asymmetry of the sand pit morphology is not the non-uniform distribution of sand grains, but more likely caused by turbulence effects. Simultaneously, within the initial 0.25 s of the pulse cycle, suspended sediment resulting from the pulsed jet in the preceding cycle gradually transports to the dune and its surrounding areas. Subsequently, from 0.25 s to 0.5 s, sediment on both sides of the pit’s bottom undergoes movement and amalgamation with the sediment that remained unsettled during the previous cycle. The findings reveal that higher jet velocities significantly enhance sediment suspension, migration, and redeposition, leading to deeper erosion and the rapid formation of the sand pit’s outline within 2 s. Additionally, the jet velocity and the impact distance are identified as critical factors influencing erosion depth and sediment dynamics. These insights advance the understanding of erosion mechanisms driven by pulsed jets, highlighting their impact on sediment transport processes. The research findings provide important guidance for dredging and ocean engineering fields and offer a theoretical basis for improving the understanding of submerged jet scouring mechanisms.

Evaluating the Diagnostic Potential of Four-Dimensional Flow Magnetic Resonance Imaging in Aortic Stenosis Diagnosis: A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis evaluates the potential of four-dimensionalflow magnetic resonance imaging(4DFM) in assessing aortic stenosis (AS) compared to traditional imaging modalities like two-dimensional phase contrast MRI (2D MRI) and transthoracic echocardiography (TTE). AS is a common and severe valvular heart disease, particularly in older adults, requiring accurate diagnosis for proper clinical management. Conventional imaging methods have limitations in capturing complex flow dynamics, prompting the need for advanced modalities like 4DFM. The objectives of the review were to determine whether 4DFM offers superior diagnostic metrics, including peak aortic jet velocity, transvalvular pressure gradients, and aortic valve area (AVA), and to identify potential advantages of 4DFM in overcoming the limitations of traditional modalities. This review included six cohort studies with 285 participants, examining the diagnostic accuracy of 4DFM in terms of peak aortic jet velocity, transvalvular pressure gradients, and aortic valve area (AVA). Studies were selected from MEDLINE (PubMed), Cochrane Library, and Google Scholar databases between December 2010 and October 2024. The study pool was limited by stringent inclusion criteria focusing on cohort studies that directly compared 4DFM with TTE or 2D MRI for AS assessment. The National Institutes of Health Quality Assessment Tool and Cochrane ROBINS-I tool were used to assess bias. Quantitative results showed that 4DFM typically measured higher AVA values than TTE, with a mean difference of 0.48 cm² (95% CI: -0.16 to 1.12). For mean pressure gradients, 4DFM reported slightly higher measurements in individual studies, but pooled results showed no significant difference compared to TTE (mean difference: 3.32 mmHg, 95% CI: -2.30 to 8.93). In terms of peak aortic jet velocity, 4DFM demonstrated a pooled mean difference of -0.18 m/s (95% CI: -0.44 to 0.08) compared to TTE. High heterogeneity was observed across studies (e.g., I² = 97% for peak velocity, I² = 93% for AVA), likely due to differences in patient populations, imaging protocols, and software for data analysis.4DFM demonstrates potential as a complementary imaging tool, particularly in complex AS cases where conventional methods like TTE may provide inconclusive results. Its capacity to capture intricate flow dynamics and deliver high spatial resolution could inform clinical decision-making, potentially influencing practice guidelines to integrate 4DFM as a supplementary tool. Limitations such as high costs, specialized training requirements, and access challenges currently restrict widespread adoption. Limitations of this review include small sample sizes, high heterogeneity, and variability in patient populations and imaging protocols. Despite these challenges, 4DFMI demonstrated superior spatial resolution and complex cardiovascular flow assessment, suggesting it could serve as a valuable complement to TTE for more detailed AS evaluation, particularly in complex cases.Future studies should aim to standardize imaging protocols, incorporate larger and more diverse populations, and conduct cost-benefit analyses to support the integration of 4DFM into clinical practice, potentially shaping future diagnostic guidelines.

Numerical Study of Hydrogen-Rich Fuel Coherent Jet in Blast Furnace Tuyere

Injecting hydrogen-rich fuel into blast furnaces is an effective strategy to reduce carbon dioxide (CO2) emissions. The present study established a three-dimensional (3D) model based on a coherent jet of hydrogen-rich fuel. The combustion characteristics and the flow, heat, and mass transfer behaviors in the reaction region were simulated by the Computational Fluid Dynamics (CFD) method. The effects of fuel jet velocity on the distributions of gas velocity, temperature, and species in the reaction region were systematically analyzed. The results show that hydrogen-rich fuel burned around the main jet, generating a high-temperature, low-density flame. As flame length increased, the main jet experienced less decay. The outward expansion of the jet caused continuous diffusion of gas temperature and its components. As the fuel jet velocity increased, the temperature along the main jet centerline rose sharply, while the length of the high-concentration gas region extended. Doubling the jet velocity increased its centerline velocity by 11% and raised the average reaction region temperature by 4.12%. The obtained highlighted results are of paramount importance for optimizing hydrogen-rich smelting in blast furnaces.

Effects of structural parameters of active pre-chamber on the combustion process of methanol/gasoline TJI rotary engine

The application of Turbulent Jet Ignition (TJI) combustion mode in spark ignition engine can improve combustion efficiency and output power. This paper innovatively proposes the application of active pre-chamber (APC) in rotary engine (RE) to realize this mode. And blending a certain percentage of methanol in gasoline to achieve carbon reduction. A three-dimensional computational model of the APC-RE was developed, and the effects of three APC structural parameters including throat section diameter, throat section length and orifice diameter on the component flow and combustion characteristics were investigated. The results showed that the APC-RE exhibited higher sensitivity to the diameter of the throat section than the length variation under the fixed active fuel injection strategy. The low length or small diameter of the throat section causes insufficient energy in the APC jet, and too high values cause unstable combustion. The optimal APC volume is achieved at a throat length of 8 mm and a diameter of 6 mm, with the highest Indicated mean effective pressure (IMEP) and Indicated thermal efficiency (ITE). Next, The APC volume was fixed and the effect of jet orifice size on RE performance was discussed and the optimal size was determined 1.25 mm, which can further optimize the jet velocity and can continue to increase IMEP and ITE by 1.24 % and 1.46 % respectively.

Numerical investigation on the liquid jet and the dynamics of the near-wall cavitation bubble under an acoustic field

The dynamics of the near-wall cavitation bubble in an acoustic field are the fundamental forms of acoustic cavitation, which has been associated with promising applications in ultrasonic cleaning, chemical engineering, and food processing. However, the potential physical mechanisms for acoustic cavitation-induced surface cleaning have not been fully elucidated. The dynamics of an ultrasonically driven near-wall cavitation bubble are numerically investigated by employing a compressible two-phase model implemented in OpenFOAM. The corresponding validation of the current model containing the acoustic field was performed by comparison with experimental and state-of-the-art theoretical results. Compared to the state without the acoustic field, the acoustic field can enhance the near-wall bubble collapse due to its stretching effect, causing higher jet velocities and shorter collapse intervals. The jet velocity in the acoustic field increases by 80.2%, and the collapse time reduces by 40.9% compared to those without an acoustic field for γ = 1.1. In addition, the effects of the stand-off distances (γ), acoustic pressure wave frequency (f), and initial pressure (p*) on the bubble dynamic behaviors were analyzed in depth. The results indicate that cavitation effects (e.g., pressure loads at the wall center and the maximal bubble temperature) are weakened with the increase in the frequency (f) owing to the shorter oscillation periods. Furthermore, the maximum radius of bubble expansion and the collapse time decrease with increasing f and increase with increasing p*. The bubble maximum radius reduces by 12.6% when f increases by 62.5% and increases by 20.5% when p* increases by 74%.

Calculation of Single and Multiple Low Reynolds Number Free Jets with a Lattice-Boltzmann Method

Numerical calculations of low-Reynolds-number freejets with a Lattice Boltzmann Method are presented. The calculated-time-averaged axial velocity of a round jet with Re=1030 matches experimental data, including the length of transition from laminar to turbulent flow. Special care was needed for the inlet conditions in order to reproduce the vena contracta phenomenon. The results for round jets with Re=1000/1500/2000 show good agreement with Finite Difference Method calculations from the literature. In principle, there is a strong sensitivity to the inlet conditions, suggesting a need in future experimental work to measure in detail the velocity profiles and turbulence quantities at the nozzle outlet. The application of turbulence at the inflow boundary of the calculation domain is often used to emulate sources of disturbances in experiments. The present study demonstrates the need to investigate the impact of turbulence level and length scale at inlet independent of each other. Finally, the calculation for a bundle of nine jets with a square inlet led to the finding that the velocity decay of the central jet is maximal when the spacing between the jets is ca. one jet diameter.

Effect of explosives charges types on the jet characteristics, penetration performance and fragmentation patterns of shaped charges

Different explosive materials have been studied numerically and experimentally to assess the efficiency of a small diameter shaped charge in terms of produced jet characteristics and penetration depth into RHA steel targets. 26 different explosives have been simulated numerically using Autodyn hydrocode, whereas recommended explosives have been loaded into small diameter shaped charges by pressing technique and tested by static firing against RHA targets in order to validate the numerical calculations. The numerical analysis has presented an intensive global view about the variation of the shaped charge jets as a potential of the loaded explosive charge efficiencies. A successful trial has been performed to measure the shaped charge jet velocity using detonation velocity VOD 812 apparatus, where its measured value was only 3.6% different from the numerical one for HMX-V5 explosive. Besides, TITAN (L3) flash X-ray radiograph has also been implemented to explore the jet profile using the same explosive type and to measure its jet tip velocity, which has only 2.1% different from that estimated numerically. Extensive fragmentation analysis has been presented, which showed increase in both the fragment number and the fragment speed when the used explosive charge is of high detonation velocity. CL-20 explosive exhibited the largest jet tip velocity and its scaled collapse velocity was found to be 140% of TNT explosive. The calculated average fragment speed has been validated and the measured fragment speed has only 2.3% difference when compared to the SPH calculations.

Numerical Analysis of the Cell Droplet Loading Process in Cell Printing

Cell printing is a promising technology in tissue engineering, with which the complex three-dimensional tissue constructs can be formed by sequentially printing the cells layer by layer. Though some cell printing experiments with commercial inkjet printers show the possibility of this idea, there are some problems, such as cell damage due the mechanical impact during cell direct writing, which include two processes of cell ejection and cell landing. Cell damage observed during the bioprinting process is often simply attributed to interactions between cells and substrate. However, in reality, cell damage can also arise from complex mechanical effects caused by collisions between cell droplets during continuous printing processes. The objective of this research is to numerically simulate the collision effects between continuously printed cell droplets within the bioprinting process, with a particular focus on analyzing the consequent cell droplet deformation and stress distribution. The influence of gravity force was ignored, cell droplet landing was divided into four phases, the first phase is cell droplet free falling at a certain velocity; the second phase is the collision between the descending cell droplet and the pre-existing cell droplets that have been previously printed onto the substrate. This collision results in significant deformation of the cell membranes of both cell droplets in contact; the third phase is the cell droplet hitting a rigid body substrate; the fourth phase is the cell droplet being bounced. We conducted a qualitative analysis of the stress and strain of cell droplets during the cell printing process to evaluate the influence of different parameters on the printing effect. The results indicate that an increase in jet velocity leads to an increase in stress on cell droplets, thereby increasing the probability of cell damage. Adding cell droplet layers on the substrate can effectively reduce the impact force caused by collisions. Smaller droplets are more susceptible to rupture at higher velocities. These findings provide a scientific basis for optimizing cell printing parameters.

Optimization of collection efficiency for a dual-row jet mining machine based on CFD-DEM coupling

Deep-sea mineral resources possess vast reserves; yet, the depositional environment is extremely harsh, and the mining challenges are significant. Overcoming the technical hurdles of deep-sea mining and protecting the marine environment to achieve sustainable development and utilization of seabed resources are major challenges in the field of marine resource development. In this work, we employ a coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) approach with the objective of enhancing the collection efficiency of deep-sea polymetallic nodules. The research focuses on adjusting and optimizing the collection parameters of a dual-jet collector. We examine the influence of the collector's jet angle and velocity on the collection efficiency. We conduct a numerical analysis of the movement characteristics of nodules, the distribution of the flow field, and the efficiency of nodule collection. The results indicate that when the rear jet angle is too small, the stripping and blocking effects on the nodules deteriorate. Conversely, when the jet angle is too large, the upwelling flow velocity decreases. The optimal collection effect is achieved with a rear jet angle of 55°. Lower jet velocities result in poorer nodule stripping, collection, and lifting. Higher jet velocities, however, increase seafloor disturbance and reduce the device's energy utilization efficiency. The collection efficiency is optimal at jet velocities ranging from 8 to 9 m/s. This research provides valuable insights for the design of high-efficiency dual-jet collector devices.

Prediction and Analysis of Borosilicate Glass Surface Deformation Induced by Flame Jet

To address the issues of low processing efficiency, poor forming accuracy, and internal damage in glass material processing, this study proposes the use of flame jet forming. However, the mechanism of flame jet processing requires further elucidation. This research investigates the relationship between the indentation morphology on the glass surface and the inlet velocity of the flame jet. A theoretical model was established through mathematical analysis to reflect this relationship. The model’s accuracy was validated using numerical simulation methods. By comparing experimental data with theoretical model results, surface tension was incorporated, and the model was iteratively optimized using MATLAB R2024a. The final optimized model demonstrated an absolute error range of 0.009 to 0.069 mm. This study confirms the feasibility of flame jet processing and enriches the understanding of its mechanism, providing a novel, efficient, and precise method for processing glass materials.

Impact of sex-specific thresholds for low flow in assessment of prognosis in concordantly and discordantly graded aortic valve stenosis.

Sex-specific low flow was recently defined as stroke volume index (SVi) ≤40 ml/m² in men and ≤32 ml/m² in women. We tested the prognostic association of these cut-offs in patients with aortic stenosis (AS) with concordantly and discordantly graded AS (CGASEL and DGASEL) based on pressure recovery adjusted aortic valve area (energy loss, EL). Data from 1351 patients with asymptomatic AS, peak jet velocity <4m/s and preserved left ventricular ejection fraction enrolled in the Simvastatin and Ezetimibe in AS study was used. DGASEL was defined as EL <1.0 cm² with mean aortic gradient <40 mmHg, and CGASEL as EL ≥1.0 cm² with mean aortic gradient <40mmHg. Patients were further grouped into normal and low flow. Outcome was combined all-cause death and hospitalization for heart failure. CGASEL with normal/low flow was present in 915/253 patients, and DGASEL with normal/low flow in 57/126 patients. During median 4.3 years follow-up, event-free survival was lower in patients with DGASEL irrespective of flow compared to CGASEL with normal flow (p<0.05). In Cox regression analysis, DGASEL with normal or low flow were both associated with increased risk of all-cause death and hospitalization for heart failure after adjustment for age, sex, heart rate, randomized study treatment, hypertension, aortic valve replacement and aortic valve calcification (p<0.05). No survival difference was found between patients with normal vs. low flow within groups of DGASEL or CGASEL. Identification of low flow by the proposed sex-specific thresholds of SVi needs more prognostic validation before application in clinical practice.

Study on smoke sealing effectiveness of the air curtain in exit bifurcated tunnel fires

The feasibility of using a smoke prevention air curtain in the exit bifurcated tunnel was investigated through 1:10 scale model experiments. The results indicated that the jet velocity and heat release rate (HRR) significantly influenced the smoke sealing effectiveness of the air curtain. However, once the jet velocity reached a certain extent, the longitudinal fire location had a relatively limited effect on the smoke sealing effectiveness. Subsequently, numerical simulations were conducted to investigate the influence of the HRR, jet velocity, longitudinal velocity, and bifurcation angle on the smoke sealing efficiency of the air curtain. The simulations were based on the evacuation strategy of bifurcated tunnel under longitudinal ventilation, assuming no smoke backflow upstream of the fire. The findings revealed that the smoke sealing efficiency was positively correlated with the jet velocity, negatively correlated with the HRR and longitudinal velocity, and somewhat increased with the increase of bifurcation angle. Additionally, a prediction model was proposed for determining the optimal air curtain jet velocity in the bifurcated tunnel. This model was developed using dimensional analysis principles and taking into account various influencing factors, which can provide valuable insights for designing smoke control measures and enhancing safety in bifurcated tunnel fires.

Left ventricular mass index and prognosis of symptomatic severe aortic stenosis in women and men

Abstract Background Symptomatic severe aortic stenosis (AS) requires surgical (SAVR) or transcatheter aortic valve replacement (TAVR), and many patients are on the procedure waiting list. The diagnosis of severe AS is based on clinical and echocardiographic criteria, such as left ventricular ejection fraction (LVEF), aortic valve area (AVA), mean transvalvular gradient, and peak aortic jet velocity. However, there is a gap in knowledge regarding the influence of left ventricular mass on the prognosis of these patients, especially considering differences between women and men. Purpose To evaluate the influence of left ventricular mass index (LVMi) on the mortality of women and men with severe AS awaiting SAVR or TAVR. Methods A prospective study analysed the death rate in 531 outpatients with symptomatic severe AS with mean transvalvular gradient ≥40 mmHg, AVA ≤1.0 cm2, or peak aortic jet velocity ≥4.0m/s at echocardiography with the indication for TAVR or SAVR in the period from April 2020 to February 2024. Baseline data included analysis of clinical characteristics, echocardiographic variables, and the presence of coronary artery disease (CAD). Statistical analyses were performed using the Kaplan-Meier (K-M) and Cox proportional hazards methods to analyze mortality rates in women and men. Results The mean age was 74.7±11.6 years, with 283 (53.3%) men. Over a follow-up period of 2.67±1.22 years, death occurred in 165 (31.1%), 148 (86%) due to cardiovascular disease, and 152 (92%) had heart failure (HF) NYHA II to IV, 51 (9,6%) had angina, and syncope in 11 (2.1%) of the patients. Patients who died had lower LVEF (61.4%±8.9% vs. 58.8%±10.8%; p=0.008) and higher LVMi (125.3±32.5 g/m2 vs. 115.5±29.3 g/m2; p=0.001). Angina, syncope, hypertension, dyslipidemia, diabetes, smoking, atrial fibrillation, and CAD prevalence were similar in living patients and in those who died. Both groups had similar echocardiographic data, such as left atrial volume, mean transvalvular gradient, and peak jet velocity. TAVR and SAVR were done in 111 (20.9%) and 162 (30.5%) patients. Of these, 21 (18.9%) and 20 (12.4%) died during follow-up, respectively. Cumulative mortality of all patients was higher with LVMi &amp;gt;115 g/m2 compared to ≤115 g/m2 (p=0.008)(Figure). In women but not in men, cumulative mortality was higher with LVMi &amp;gt;115 g/m2 compared to ≤115 g/m2 (p=0.046). Cox multivariate analysis, adjusted for LVEF, LVMi, CAD, and age, showed LVMi as an independent variable for death [HR=1.50 (95%CI: 1.10-2.05); p=0.011]. LVEF [HR=0.97 (95%CI: 0.95-0.99); p=0.009] and LVMi [HR=1.75 (95%CI: 1.10-2.79); p=0.016] were independent variables for death in women, but not in men. Conclusion Women with higher LVMi and lower LVEF should have valve intervention prioritized.Figure

LncRNA MEG3 promotes aortic valve calcification by inducing osteoblast differentiation via Wnt catenin signaling pathway

Abstract Background Calcific aortic valve stenosis (CAVS) is the most common valvular heart disease in elderly population. This study aimed to investigate the role of long non-coding RNAs (lncRNAs) in the development of CAVS. Methods ldlr-/-mice were feeding with western diet for 6 months to induce CAVS. RNA-seq analysis was performed to identify differentially expressed molecular signaling between aortic valves of CAVS mice and control mice. The degree of aortic stenosis was detected by ultrasound. Calcium salt deposits were detected by Haematoxylin and eosin (H&amp;E) staining, Von Kossa staining and alizarin red S staining. PCR and western blotting were employed to detect osteogenic differentiation markers after various interventions. Results A mouse CAVS model was successfully established, as evidenced by increased thickness and calcium deposition in the aortic valve leaflets and increased transvalvular peak jet velocity. RNA-seq analysis showed that lncRNA MEG3 was significantly enriched in aortic valves of CAVS mice as compared to that of control mice. MEG3 expression in aortic valve, assessed by RNA in situ hybridization and PCR, was also significantly upregulated during the osteoblast differentiation of AVICs in vitro. Gain- and loss-of-function experiments indicate that MEG3 could indeed promote osteoblast differentiation of primary AVICs as evidenced by increased calcified nodule formation and expressions of osteoblast differentiation markers (Runx2 and osterix). Consistent with these in vitro data, MEG3 knockdown in vivo through tail injection of antisense oligonucleotide chain MEG3 (ASO-MEG3) at 6 weeks interval for 12 weeks significantly attenuated aortic valve calcification in CAVS mice. Subsequent KEGG analysis demonstrated that the Wnt/β-catenin signaling pathway was significantly enriched during the CAVS progression. Overexpression of MEG3 activated the Wnt/β-catenin signaling pathway and upregulated osteogenic protein expressions, while this upregulation could be significantly ameliorated by Dickkopf 1, a Wnt/β-catenin pathway inhibitor. Conclusion Present study demonstrates that LncRNA MEG3 could promote aortic valve calcification by inducing osteoblast differentiation via activating Wnt/β-catenin signaling pathway. Our results provide experimental evidence of targeting MEG3 and Wnt/β-catenin signaling pathway as potential promising therapeutic option for prevention and treatment of aortic valve calcification.

Overview of the risk of myocardial infarction in patients with aortic stenosis: insights from the VALVENOR Registry

Abstract Background Close interaction between aortic stenosis (AS) and coronary artery disease (CAD) has been suggested. However, the risk of myocardial infarction (MI) in patients with AS is poorly described outside the context of aortic valve replacement. Objectives To assess the incidence, correlates and impact on outcomes of MI occurrence in patients with different degrees of AS severity. Methods Between 2016 and 2017, the multicenter prospective VALVENOR registry enrolled 2,830 outpatients with native valvular AS (peak aortic jet velocity (Vmax) ≥ 2.5m/s). AS was defined as mild (Vmax 2.5-2.9), moderate (Vmax 3-3.9) or severe (Vmax ≥4). MI was defined using the 4th universal definition (type 2 MI were not considered). Results The mean age was 76.0 years, 54% of the patients were men and 18.3% had experienced prior coronary event (PCE). Altogether, one third (n=820 [30.3%]) of the patients had diabetes. At 5 years, the cumulative incidence of MI (death as competing event) was only 2.5% (n=72, 1/3 of ST-elevation MI). Sixty MI (83.3%) were categorized as type 1 MI while 12 were peri-procedural MI (surgical aortic valve replacement, n=5; transcatheter aortic valve replacement, n=2; coronary artery bypass surgery, n=1; percutaneous coronary intervention, n=3; coronary angiography, n=1). PCE and angina symptoms were associated with an increased risk, whereas female gender with a decreased risk. By contrast, AS severity was not associated with the risk of MI. Five-year cumulative incidence of MI was 6.5% [95% CI, 4.5 - 8.9] in patients with PCE vs. 1.7% [95% CI, 1.2 - 2.3] in patients with no PCE (P&amp;lt;0.001), 8.3% [95% CI, 4.1 - 14.4] in patients with angina vs. 2.3% [95% CI, 1.8 - 2.9] in patients without angina (P&amp;lt;0.001), and 3.2% [95% CI, 2.4 - 4.2] in men vs. 1.8% [95% CI, 1.1 - 2.6] in women (P=0.014). Subsequent mortality was high and at 52.8% during follow-up (median 648 days after MI occurrence). When analyzed as a time-dependent variable, incident MI was a powerful predictor of mortality (HR=2.00, P&amp;lt;0.001 after adjustment). Conclusions In patients with AS, the risk of MI is relatively low especially in patients without PCE and without angina. No association between the risk of MI and AS severity was observed. Although rare, incident MI is strongly associated with subsequent mortality.

Discordance between symptomatic response and changes in cardiac structure and function one year after transcatheter aortic valve implantation

Abstract Background Symptomatic improvement is one of the main goals of transcatheter aortic valve implantation (TAVI) in patients with severe symptomatic aortic stenosis. We hypothesized that the degree of symptomatic response after TAVI is associated with improvement in cardiac structure and function after TAVI. Purpose We aimed to evaluate 1) the change in symptomatic burden measured by New York Heart Association (NYHA) and Canadian Cardiovascular Society (CCS) functional class after TAVI, 2) the change in echocardiographic structural and functional parameters after TAVI, and 3) the association of symptomatic response with echocardiographic response as well as long-term survival. Methods In patients undergoing TAVI, we assessed New York Heart Association (NYHA) and Canadian Cardiovascular Society (CCS) functional class at 12 months. Symptomatic response was defined as NYHA/CCS class I or ≥ 1 improvement in NYHA/CCS class compared to baseline at 12 months. Echocardiographic images at baseline and 6-18 months post-TAVI were analysed using an automated, validated, deep-learning workflow. Logistic regression was used to assess association between change in echocardiographic parameters and symptomatic change at 12 months. The association of symptomatic response and echocardiographic changes in the first 12 months after TAVI with survival beyond 12 months, was evaluated by landmark analysis using Kaplan-Meier analysis. Results Among 868 TAVI patients (median age 80 years, 53% female), the majority (74%) had NYHA/CCS class III at baseline and 77% of patients experienced improvement in symptoms at 12 months post-TAVI (Figure 1). Patients without an improvement in symptoms more often had COPD, atrial fibrillation and more heart failure medications compared to responders. Left ventricular systolic function did not show improvement compared to baseline, whereas a modest improvement in left atrial volume index, left ventricular mass index, E/A ratio, E/e’ ratio, mean e’ and tricuspid regurgitation peak jet velocity was observed. Symptomatic response was not associated with echocardiographic response. Beyond 12 months, patients with symptomatic improvement had lower mortality than those without symptomatic improvement (1.5 vs. 2.4 per 10 patient years; p = .001), whereas changes in echocardiographic parameters were not associated with subsequent mortality (Figure 2). Conclusion Patients undergoing TAVI for symptomatic severe aortic stenosis, showed substantial symptomatic improvement at one year after the procedure, whereas only a modest improvement in echocardiographic parameters was observed. Improvement in symptoms was not associated with improvement in echocardiographic measures of cardiac structure and function. Symptomatic improvement, but not improvement in cardiac structure and function at 12 months, was a strong predictor of subsequent survival.Change in NYHA/CCS class after TAVISymptoms and echo versus mortality

Prevalence and outcomes of patients with discordant high gradient aortic stenosis

Abstract Background Conflicting prognostic results have been reported in patients with discordant high gradient aortic stenosis (DHG-AS, the combination of a mean pressure gradient ≥40 mmHg and an aortic valve area (AVA) &amp;gt;1cm² ). Moreover, existing studies only included selected patients without concomitant aortic regurgitation. Purpose We assessed the prevalence and survival of patients presenting with DHG-AS in an unselected group of consecutive patients presenting to the echocardiography laboratory of a tertiary referral center. Methods 3,547 adult patients with AVA ≤1.5cm² and peak aortic jet velocity ≥2.5m/s or mean gradient ≥25mmHg who presented between 2005 and 2015 were included. Baseline clinical and echocardiographic data, and, when available, aortic valve calcium score (AVC) were collected in an institutional database, with subsequent retrospective analysis. The primary endpoint was all cause mortality during follow-up. Results DHG-AS was observed in 163 patients (11.6% of all patients with a gradient ≥ 40mmHg). After adjustment for potential confounders, overall mortality rate of patients with DHG-AS was similar to that of concordant severe AS (AVA ≤1cm², mean gradient ≥40mmHg; CSev-AS) patients (N=1,243; HR: 0.98[0.68;-1.44]; p=0.91), and discordant low gradient-AS (AVA ≤1cm²; gradient &amp;lt;40 mmHg; HGDLG-AS) patients (N=1,131, HR: 0.85[0.58-1.26]; p=0.42), and was worse than that of concordant moderate AS (AVA &amp;gt;1.0cm², gradient &amp;lt;40mmHg; CMod-AS) patients (N=1,010; HR: 0.54[0.36-0.81]; p=0.003, Fig 1). After adjustment for aortic velocities, aortic regurgitation had no significant impact on survival. Calcium scoring was performed in 716 patients, including 40 patients with DHG-AS. AVC in DHG-AS was higher than in patients with CMod-AS and DLG-AS, and not significantly different from that of CSev-AS. The AVC ratio (AVC divided by the sex-specific thresholds) was higher in patients with DHG-AS as compared to both CMod-AS and DLG-AS patients (Fig 2). Conclusions DHG-AS is not uncommon. Although an AVA ≥1.0 cm² is often seen as reassuring and mistaken as moderate AS, a high-pressure gradient conveys a poor prognosis, whatever the AVA and independently of the presence of concomitant aortic regurgitation.

Pulmonary valve acceleration fraction as a novel echo parameter to evaluate systolic pulmonary artery pressure during exercise echocardiography

Abstract Background/Introduction Long-COVID is a disabling chronic condition. Some patients have features of exercise-induced pulmonary hypertension (PHT) but non-invasive assessment during exercise stress echo (SE) is often limited by absence of reliable jet of tricuspid regurgitation (TR). We aimed to investigate novel Doppler echo parameters elicited from right ventricular (RV) outflow tract to aid diagnosis of exercise induced PHT among patients referred to our centre with Long-COVID symptoms. Purpose We investigated the ratio of the pulmonary valve acceleration time (PV AccT) to RV ejection time (RV ET) to calculate the pulmonary acceleration fraction (PV AccT/RV ET), thereby adjusting to heart rate. To identify its utility to estimate pulmonary artery pressure (PASP) during SE we correlated the PV AccT/RV ET and the TR-estimated RV systolic pressure (RVSP) in patients referred for evaluation of exercise-induced PHT in Long-Covid patients. Methods We developed a dedicated Covid-19 SE protocol to assess RV and pulmonary hemodynamics. From November 2022 to February 2023 all consecutive patients with Long-COVID symptoms underwent supine bike exercise with 3-min increments of workload of 25W. We did not evaluate the inferior vena cava during exercise, therefore estimated pressures from maximal TR jet velocities only. Results We enrolled 93 consecutive patients. The mean age was 50.1 years, 42.9% were female. No patients had RV impairment or RVSP &amp;gt;40mmHg at baseline. The average exercise time was 12.4 minutes, only 33% achieved the sub-maximum target heart rate (THR), in 50/93 (53.7%) reasons for termination were recorded as shortness of breath. The pulmonary acceleration fraction could be recorded in every patient at rest and at stress, while 20/92 (21.7%) patients had insufficient spectral Doppler profile of TR to estimate RVSP. The PV acceleration fraction was correlated with the available RVSPs during exercise (Spearman’s ϱ -0.446 (95% CI -0.606- -0.251[p&amp;lt;0.0001]). ROC analysis indicated a pulmonary acceleration fraction ≤0.44 was associated with the maximum Youden index to discriminate an increase in RVSP &amp;gt;20mmHg during exercise (AUC =0.731 [p&amp;lt;0.001]) with a sensitivity and specificity of 70.0% and 80.0%. In logistic regression analysis, a PV acceleration fraction ≤0.44 was independently associated with an increase in RVSP&amp;gt;20mmHg during exercise independently of age, gender and baseline LVEF, LVEDV, TAPSE and baseline RVSP (p&amp;lt;0.001). Conclusions Significant proportion of Long-COVID patients are limited by symptoms and not able to achieve THR during exercise. PV Acc T/ PV ET correlates well to RVSP and can be used to estimate PA pressure. A threshold of 0.44 appears independently associated with a benchmark of PA systolic pressure increase of &amp;gt;20mmHg. Further studies needed to evaluate this new marker of pulmonary hypertension in other group of patients.

Core laboratory versus center-reported echocardiographic assessment of the native and bioprosthetic aortic valve

Abstract Background The use of a central echocardiographic core laboratory (ECL) is advised to minimize measurement variation and heterogeneity in clinical trials. Insights into quantitative differences between ECL and center-reported echocardiographic assessment of the native and bioprosthetic aortic valve are lacking. We aimed to explore clinically relevant differences between these evaluations. Methods Data were used from the PERIcardial SurGical AOrtic Valve ReplacemeNt (PERIGON) Pivotal Trial for the Avalus valve. In this trial, patients with an indication for surgical aortic valve replacement (SAVR) due to aortic stenosis or regurgitation (AR) were enrolled. Serial echocardiographic examinations were performed at each center and reanalyzed by an independent ECL. For the bioprosthetic valve analysis, postoperative data throughout 5-year follow-up were pooled. Differences between the ECL and the centers in continuous parameters were quantified in mean differences and intraclass correlation coefficients (ICCs). Between-center differences were illustrated by plotting standardized mean differences (SMDs) between centers and the ECL for the 10 sites that implanted the most prostheses. Agreement on AR, paravalvular leak (PVL), and prosthesis-patient mismatch (PPM) classification was investigated using Cohen’s kappa coefficients. Results The analysis on the native aortic valve was performed on 1118 patients. The relative mean difference was largest for the left ventricular outflow tract (LVOT) area, followed by stroke volume and effective orifice area (index), with center-reported values being 11-7% higher (Table 1). High ICCs of around 0.90 were observed for peak aortic jet velocity, mean pressure gradient, and the velocity-time integral across the aortic valve. More than 5000 echocardiograms were available for the bioprosthetic valve analysis. Therein, comparable results were observed. In Figure 1, differences in assessment on center level are illustrated. The SMDs for peak velocity were between 0 and 0.5 for all centers, while there was more heterogeneity between centers for other parameters. The kappa coefficient was 0.59 (95% confidence interval [CI] 0.56, 0.63) for agreement on native AR, 0.28 (95% CI 0.18, 0.37) for PVL, and 0.42 (95% CI 0.40, 0.44) for PPM. Conclusions For echocardiographic assessment of the native and bioprosthetic aortic valve, agreement between the ECL and the clinical centers varies by parameter and by center. There is high agreement on continuous-wave Doppler-related measurements. On the contrary, agreement is low for parameters that involve measurement of the LVOT diameter. These results provide important context for the interpretation of aortic valve performance in studies that lack central ECL evaluation.