Pressure Gradient Research Articles

Influence of Higher Order Chemical Reaction on Rotational and Permeable Radiative Flow with Interruption of Micro-organism

Objective: The concentration on the function of the non-Newtonian radiative Casson Nanofluid model via a permeable and stretchable cone has been investigated. The innovation of the problem is Casson, taken as base fluid, and Manganese Ferrite is dropped in the base fluid under the action of a higher-order chemical reaction. This study examines the convective magneto-hydrodynamic (MHD) flow of a conducting micro-organism fluid confined within a horizontal channel via stimulus of a transverse magnetic field (MHD) and thermal radiation parameter. Methods: The foremost partial differential equations (PDE) are changed into an arrangement of ordinary differential equations by applying adequate corresponding transform. The outputs of these equations are performed numerically employing the RK method and computed by well-established BVP4C MATLAB software Special features such as radiation, heat generation/absorption, Joule heating, and electrically conductive MHD are examined. Skin friction and Nusselt number are incorporated into the flow and results are tabulated and outcomes are discussed graphically. Findings: The system incorporates the effects of micro-organism, pressure gradient and the movement of the moving cone. The generated heat is significant enough to cause radiation from both the fluid and the dust particles. Solutions for velocity and temperature distributions of the fluid, as well as the velocity and energy of the dust particles, are obtained using a perturbation scheme. The analytical impact of numerous geometrical parameters on both fluid and dust particle profiles has been analyzed and illustrated graphically. The impact of nonlinear partial derivative formulations is developed subjected to boundary layer theory. Novelty: As labelled in the results, heterogeneous is the examination of thermal radiation in science and technology such as liquid metal fluids different momentum devices for missiles, and turbines of gas effects on thermal radiation are exhibited and distinguished in various investigations and mathematical applications uses of the view in which radiant production be dependent on temperature are point out as a new value to the prevailing literature. Keywords: Thermal radiation, Brownian motion, Buoyancy flow, Chemical reaction, Heat and Mass transfer, Rotating cone

Energy Conversion Associated With Anomalous Magnetic Topology Sublayers in the Inner Low‐Latitude Boundary Layer

AbstractThe low‐latitude boundary layer (LLBL) is a crucial region for the transfer of mass, momentum, and energy between the solar wind and the planetary magnetosphere. However, the processes of energy conversion within this layer are not well understood. In this study, the anomalous magnetic topology sublayers (AMTSs) within Earth's inner LLBL are investigated during the local reconnection inactive period, using data from the Magnetospheric Multiscale (MMS) mission. We present the first in situ observations showing that these AMTSs lead to significant energy conversion within the inner LLBL. The electron populations in AMTSs are dominated by either the magnetospheric or magnetosheath populations, creating a substantial electron temperature gradient between these sublayers. This temperature gradient, in turn, generates non‐ideal electric fields through the pressure gradient term. Our findings improve the understanding of dynamics in the planetary LLBL, highlighting the importance of AMTSs in the energy conversion process.

On the laminar solutions and stability of accelerating and decelerating channel flows

We study the effect of acceleration and deceleration on the stability of channel flows. To do so, we derive an exact solution for laminar profiles of channel flows with an arbitrary, time-varying wall motion and pressure gradient. This solution then allows us to investigate the stability of any unsteady channel flow. In particular, we restrict our investigation to the non-normal growth of perturbations about time-varying base flows with exponentially decaying acceleration and deceleration, with comparisons to growth about a constant base flow (i.e. the time-invariant simple shear or parabolic profile). We apply this acceleration and deceleration through the velocity of the walls and through the flow rate. For accelerating base flows, perturbations never grow larger than perturbations about a constant base flow, while decelerating flows show massive amplification of perturbations – at a Reynolds number of $500$ , properly timed perturbations about the decelerating base flow grow $ {O}(10^5)$ times larger than perturbations grow about a constant base flow. This amplification increases as we raise the rate of deceleration and the Reynolds number. We find that this amplification arises due to a transition from spanwise perturbations leading to the largest amplification to streamwise perturbations leading to the largest amplification that only occurs in the decelerating base flow. By evolving the optimal perturbations through the linearized equations of motion, we reveal that the decelerating base flow achieves this massive amplification through the Orr mechanism, or the down-gradient Reynolds stress mechanism, which accelerating and constant base flows cannot maintain.

Impact of spanwise rotation on flow separation and recovery behind a bulge in channel flows

Direct numerical simulations of spanwise-rotating turbulent channel flow with a parabolic bump on the bottom wall are employed to investigate the effects of rotation on flow separation. Four rotation rates, $Ro_b := 2\varOmega H/U_b = \pm 0.42$ , $\pm$ 1.0, are compared with the non-rotating scenario. The mild adverse pressure gradient induced by the lee side of the bump allows for a variable pressure-induced separation. The separation region is reduced (increased) when the bump is on the anti-cyclonic (cyclonic) side of the channel, compared with the non-rotating separation. The total drag is reduced in all rotating cases. Through several mechanisms, rotation alters the onset of separation, reattachment and wake recovery. The mean momentum deficit is found to be the key. A physical interpretation of the ratio between the system rotation and mean shear vorticity, $S:=\varOmega /\varOmega _s$ , provides the mechanisms regarding stability thresholds $S=-0.5$ and $-$ 1. The rotation effects are explained accordingly, with reference to the dynamics of several flow structures. For anti-cyclonic separation, particularly, the interaction between the Taylor–Görtler vortices and hairpin vortices of wall-bounded turbulence is proven to be responsible for the breakdown of the separating shear layer. A generalized argument is made regarding the essential role of near-wall deceleration and resultant ejection of enhanced hairpin vortices in destabilizing an anti-cyclonic flow. This mechanism is anticipated to have broad impacts on other applications in analogy to rotating shear flows, such as thermal convection and boundary layers over concave walls.

The histological grading of fibrosis in Budd-Chiari syndrome: A chronic liver disease, different from others.

Budd-Chiari syndrome (BCS) is an uncommon disease caused by hepatic venous outflow obstruction. They can result in centrilobular fibrosis, nodular regenerative hyperplasia and cirrhosis. Assessing liver fibrosis is crucial for determining the stage of BCS, predicting disease progression and guiding treatment decisions. Although this pathology has been known for decades, no useful grading system was assigned. This study aims to introduce a histologic fibrosis grading system for BCS patients. All patients from 2017 to 2022 (Sanjay Gandhi Postgraduate Institute of Medical Sciences [SGPGIMS]), Lucknow diagnosed with BCS for whom liver biopsy was performed were included in the study. The Budd-Chiari syndrome-Hepatic Fibrosis system (BCS-HFS) was implemented to grade fibrosis. The fibrosis grade was compared with the fibrosis percentage area and a correlation was found with the hemodynamic variables (hepatic venous pressure gradient[HVPG])and the prognostic scores. There were 56 patients with BCS. The median age was 27years, with a male-female ratio of 1.8:1. There was a significant difference in the fibrosis percentage, hemorrhage percentage and model for end-stage liver disease (MELD) score among the BCS-HFS grades (p < 0.05). There was a significant correlation between BCS-HFS and HVPG (ρ = 0.699, p < 0.001) and the MELD prognostic score (ρ = 0.474, p < 0.001). BCS-HFS is applicable for grading fibrosis in BCS. It can help in uniform histopathology reporting and for further prospective and comparative studies.

Esophageal pressure as estimation of pleural pressure: a study in a model of eviscerated chest.

Transpulmonary pressure is the effective pressure across the lung parenchyma and has been proposed as a guide for mechanical ventilation. The pleural pressure is challenging to directly measure in clinical setting and esophageal manometry using esophageal balloon catheters was suggested for estimation. However, the accuracy of using esophageal pressure to estimate pleural pressure is debated due to variability in the mechanical properties of respiratory system, esophagus and esophageal catheter. Furthermore, while a vertical pleural pressure gradient exists across lung regions, esophageal pressure balloon provides a single value, representing, at most, the pressure surrounding the esophagus. In a swine model with a preserved esophagus and a single homogenous, easily measurable intrathoracic pressure, we evaluated esophageal pressure's agreement with intrathoracic pressure at different positive end-expiratory pressure (PEEP) levels (0, 5, 10, 15 cmH2O). We assessed the improvement of measurement accuracy by correcting absolute esophageal values using a previously described technique, that accounts for the pressure generated by the esophageal wall in response to esophageal balloon inflation. The study involved five swine, wherein two different esophageal catheters were used alongside the four distinct PEEP levels. Swings, uncorrected and corrected absolute esophageal pressures (end-inspiratory, end-expiratory) were compared with their respective intrathoracic pressures. The effect of correction technique was assessed with manual incremental step inflation procedure. We found that both catheters significantly overestimated absolute esophageal pressure compared to intrathoracic pressure (5.01 ± 3.32 and 6.06 ± 5.62 cmH2O at end-expiration and end-inspiration, respectively), with error increasing at higher positive end-expiratory pressure levels (end-expiration: 2.36 ± 2.03, 3.77 ± 1.37, 6.24 ± 2.51 and 7.69 ± 4.02 for each PEEP level, P < 0.0001; end-inspiration: 1.71 ± 2.10, 3.70 ± 1.73, 7.67 ± 3.62 and 11.14 ± 7.60 for each PEEP level, P = 0.0004). Applying the correction technique significantly improved agreement for absolute values (0.82 ± 1.62 and 1.86 ± 3.94 cmH2O at end-expiration and end-inspiration, respectively). Esophageal pressure swings accurately estimated intrathoracic pressure swings at low-medium intrathoracic pressures (-0.64 ± 0.62, -0.07 ± 0.53, 1.43 ± 1.51, and 3.45 ± 3.94 at PEEP 0, 5, 10 and 15 cmH2O, respectively; P = 0.0197). The correction technique, based on the mechanical response of esophageal wall to the balloon inflation, is fundamental for obtaining reliable estimations of absolute intrathoracic pressure values, and for ensuring its correct application in clinical setting.

An Arteriovenous Bioreactor Perfusion System for Physiological In Vitro Culture of Complex Vascularized Tissue Constructs

Background: The generation and perfusion of complex vascularized tissues in vitro requires sophisticated perfusion techniques. For multiscale arteriovenous networks, not only the arterial, but also the venous, biomechanical and biochemical conditions that physiologically exist in the human body must be accurately emulated. For this, we here present a modular arteriovenous perfusion system for the in vitro culture of a multi-scale bioartificial vascular network. Methods: The custom-built perfusion system consisted of two circuits: in the arterial circuit, physiological arterial biomechanical and biochemical conditions were simulated using a modular set-up with a pulsatile peristaltic pump, compliance chambers, and resistors. In the venous circuit, venous conditions were emulated accordingly. In the center of the system, a bioartificial multi-scale vascularized fibrin-based tissue was perfused by both circuits simultaneously under biomimetic arteriovenous conditions. Culture conditions were monitored continuously using a multi-sensor monitoring system. Results: The physiological arterial and venous pressure- and flow-curves, as well as the microvascular arteriovenous oxygen partial pressure gradient, were accurately emulated in the perfusion system. The multi-sensor monitoring system facilitated live monitoring of the respective parameters and data-logging. In a proof-of-concept experiment, vascularized three-dimensional fibrin tissues showed sustained cell viability and homogenous microvessel formation after culture in the perfusion system. Conclusions: The arteriovenous perfusion system facilitated the in vitro culture of a multiscale vascularized tissue under physiological pressure-, flow-, and oxygen-gradient conditions. With that, it presents a promising technique for the in vitro generation and culture of complex large-scale vascularized tissues.

Correlation between the diameter of esophageal varices measured using a virtual ruler under endoscopy and portal pressure gradient

BackgroundEsophageal variceal diameter (EVD) is a crucial factor in determining the risk of esophageal variceal bleeding, which is associated with an increased portal pressure gradient (PPG). However, research into the relationship between EVD and PPG has been limited, primarily because the assessment of EVD depends on visual estimation during endoscopy. Recently, we developed an artificial intelligence (AI)-based method to accurately detect EVD. In this study, we aim to investigate the correlation between EVD and PPG, with the goal of evaluating EVD as a potential non-invasive indicator of PPG.MethodsThis study included both retrospective and prospective data from 128 patients diagnosed with portal hypertension and gastroesophageal varices, gathered from two medical institutions. Clinical data including PPG, biochemical markers, and routine blood tests were collected. In the retrospective phase, EVD was evaluated using an AI-based virtual ruler. In the prospective phase, PPG was measured using radiological intervention methods, and EVD was measured during endoscopy with the aid of AI.ResultsA positive correlation between PPG and EVD was identified (r = 0.521, P &amp;lt; 0.001), which was further supported by multivariate linear regression analysis (b = 6.521, t = 6.872, P &amp;lt; 0.001). When patients were stratified into two groups based on PPG levels (27 patients with PPG &amp;lt; 20 mmHg and 101 patients with PPG ≥ 20 mmHg), a significant difference in EVD was observed between the groups (OR = 29.275, 95% CI 5.590–153.304, P &amp;lt; 0.001), with larger EVD in the higher PPG group. These findings suggest that EVD may serve as a predictor of adverse events associated with elevated PPG levels. In addition, receiver operating characteristic (ROC) curve analysis showed that EVD had an accuracy of 0.814 in diagnosing PPG function (standard error 0.048, 95% CI 0.720-0.908; P &amp;lt; 0.001), indicating that PPG levels are likely to exceed 20 mmHg when the variceal diameter is greater than 1.1 cm.ConclusionEVD demonstrated a positive correlation with PPG and could potentially be used as a predictive marker for assessing PPG levels. These findings provide novel insights for the non-invasive evaluation of PPG in clinical practice.

Sutureless Bioprostheses for Aortic Valve Replacement: An Updated Systematic Review with Long-Term Results

Background: In recent years, in case of aortic valve replacement (AVR), a significant increase in the use of bioprostheses has been observed. The Perceval sutureless bioprosthesis has proven to be safe and reliable in the short and mid-term, with limited but promising long-term results. An updated systematic review with the long-term results of patients who underwent a sutureless bioprosthesis implantation with a Perceval biological valve is herewith presented. Methods: Studies published between 2015 and 2024, including the long-term outcomes—with clinical as well as echocardiographic information for up to five years—of patients who underwent a Perceval implantation for AVR were selected from the published literature. The Cochrane GRADE system was used to assess the study quality, and the risk of bias in non-randomized studies (ROBINS-I) tool was used to evaluate studies. Results: Ten studies were selected with an overall number of 5221 patients. The long-term survival ranged from 64.8 to 87.9%, freedom from structural valve degeneration (SVD) from 96.1 to 100%, freedom from significant paravalvular leak from 98.5 to 100%, freedom from prosthetic endocarditis from 90.7 to 99%, and freedom from reintervention from 94 to 100%. The long-term mortality ranged from 6.5 to 27.4%. SVD was observed in 0–4.8% patients. Significant paravalvular leak was observed in 0–3.4% patients, and infective endocarditis was observed in 0–3.4%. A bioprosthesis-related reintervention at long-term follow-up was required for 0–4.3% of patients, and 1.7–7.1% of patients required a late new pacemaker implantation. The transprosthetic mean pressure gradient ranged from 9 to 14.7 mmHg, peak pressure gradient ranged from 17.8 to 26.5 mmHg, and EOA ranged from 1.5 to 1.7 cm2. Conclusions: This systematic review shows that there is still a paucity of data about sutureless bioprostheses. Nevertheless, the clinical results from prospective studies or retrospective series are encouraging. Medium- and long-term results seem to support the increasing use of this type of prosthesis.

Placement of Recirculation Channel Casing Treatment in Transonic Fans: A Flow Physics Approach

This study investigates the effects of recirculation channel casing treatment positioning in a transonic fan. Recirculation channels are a passive casing treatment, consisting of an injection and extraction port connected by a secondary flowpath. Casing treatments typically extend stall margin at the cost of efficiency. However, in a transonic flowfield, strong pressure gradients can introduce an important unsteady component to the recirculation channel flow, giving these channels the potential to reduce this tradeoff by timing the injection and removal of the recirculated flow for maximum effectiveness. This timing aspect of the recirculation channel can be designed using the circumferential positioning (clocking) of the injection port relative to the extraction port. The presented results show two stability-enhancing mechanisms. First, the oscillation-attenuation mechanism improves flow stability by increasing the mean axial velocity at the tip and attenuating the oscillation of the shock and tip leakage vortex. Second, the tip leakage vortex (TLV) energization mechanism improves flow stability by injecting a jet that locally energizes the TLV. This study demonstrates that the stability-enhancing mechanism of the recirculation channel is determined by effective clocking.

A momentum-conserving wake superposition method for wind-farm flows under pressure gradient

Pressure gradient over topography will significantly affect wind-farm flow. However, knowledge gaps still exist on how to superpose wind-turbine wakes in the wind-farm flow analytical model to account for this effect, leading to systematic errors in evaluating wind-farm wake effects. To this end, we derive an implicit momentum-conserving wake superposition method under pressure gradient (PG-IMCM) based on the total momentum deficit equation, which is linearised by the convection velocity introduced by Zong &amp; Porté-Agel (J. Fluid Mech., vol. 889, 2020, A8). The PG-IMCM method consists of the linear-weighted sum of individual velocity deficits, the sum of the individual pressure correction terms and the total pressure correction term. Based on a sensitivity analysis, we demonstrate that the last two terms nearly cancel out and, thus, can be neglected, resulting in a simplified form, which has the same form as its counterpart under zero pressure gradient but with the single-wake quantities redefined based on the wake model under pressure gradient. This motivates us to further examine the performance of the combination of five empirical superposition methods and the stand-alone wake model under pressure gradient. Validation results based on large-eddy simulation show that PG-IMCM has an overall satisfactory performance in both the magnitude and shape of the velocity-deficit profiles, provided that the stand-alone turbine wake can be modelled accurately, which is virtually identical with its simplified form. Further comparison with empirical superposition methods shows that local linear and wind product superposition methods based on the updated base flow also have comparable performance, with only discernable differences with the PG-IMCM method in the near-wake region of downstream turbines. Therefore, they are two attractive methods for engineering applications.

Response of the nephron arterial network and its interactions to acute hypertension: a simulation.

We simulated the dynamics of a group of 10 nephrons supplied from an arterial network and subjected to acute increases in blood pressure. Arterial lengths and topology were based on measurements of a vascular cast. The model builds on a previous version exercised at a single blood pressure with 2 additional features: pressure diuresis and the effect of blood pressure on efferent arteriolar vascular resistance. The new version simulates autoregulation, and reproduces tubule pressure oscillations. Individual nephron dynamics depended on mean arterial pressure and the axial pressure gradient required to cause blood flow through the arteries. Rhythmic blood withdrawal into afferent arterioles caused blood flow fluctuations in downstream vessels. Blood pressure dependent changes in nephron dynamics affected synchronization metrics. The combination of vascular pressure gradients and oscillations created a range of arterial pressures at the origins of the 10 afferent arterioles. Because arterial blood pressure in conscious animals has 1/f dynamics, we applied an arterial pressure pattern with such dynamics to the model. Amplitude of tubule pressure oscillations were affected by the 1/f blood pressure fluctuations, but the oscillation frequencies did not change. The pressure gradients required to deliver blood to all afferent arterioles impose a complexity that affects nephrons according to their locations in the network, but other interactions compensate to ensure the stability of the system. The sensitivity of nephron response to location on the network, and the constancy of the tubular oscillation frequency provide a spatial and time context.

Impact of a free normal velocity boundary on the modelling of external MHD modes

Free normal-flow (NF) conditions at the plasma boundary are shown to be essential for three-dimensional magnetohydrodynamic (MHD) simulations to agree with linear stability theory. A comparative verification study is presented between two different formulations of the boundary conditions (BCs) for velocity perturbations: (i) fully consistent free NF implementation and (ii) fixed NF formulation, neglecting flow perturbations at the numerical boundary. Numerical results are compared with consolidated figures of merit from the linear theory of external kink modes. We consider two classes of initial equilibria presenting different numerical challenges: a uniform current channel surrounded by pure vacuum and a shaped Wesson-like equilibrium, with smooth (polynomial) radial dependency. Only the fully consistent free NF formulation is invariably accurate in modelling the plasma interface at the numerical boundary, without the need of enforcing a pseudovacuum region at the edge of the simulation domain, as in most analogous past studies. This study employs the cylindrical code SPECYL (Cappello &amp; Biskamp, Nucl. Fusion, vol. 36, no. 5, 1996, p. 571) that solves a full-MHD model without pressure gradients, whose fully consistent resistive wall module with free NF BCs was recently successfully verified against the independent code PIXIE3D (Spinicci et al., AIP Adv., vol. 13, no. 9, 2023, p. 095111).

Mass transport modelling of two partially miscible, multicomponent fluids in nanoporous media

High-pressure fluid transport in nanoporous media such as shale formations requires further understanding because conventional continuum approaches become inadequate due to their ultralow permeability and complexity of transport mechanisms. We propose a species-based approach for modelling two partially miscible, multicomponent fluids in nanoporous media – one that does not rely on conventional bulk fluid transport frameworks but on species movement. We develop a numerical model for species transport of partially miscible, non-ideal fluid mixtures using the chemical potential gradient as the driving force. The model considers the binary friction concept to include the friction between fluid molecules as well as between fluid molecules and pore walls, and incorporates the key multicomponent transport mechanisms – Knudsen, viscous and molecular diffusion. Under single-phase conditions, the system under consideration is quantified by introducing multicomponent Sherwood number (Sh), Péclet number (Pe) and fluid–solid friction modulus (φ). Despite the complexity of fluid transport in nanopores, the steady-state single-phase transport results reveal the contribution of diffusion in nanopores, where all parameters collapse on a set of master curves for the multicomponent Sh with a dependence on multicomponent Pe and φ. Unsteady state, two-phase transport modelling of the codiffusion process shows that light and intermediate alkanes are produced much higher than heavy alkanes when the vapour phase appears. We demonstrate that the pressure gradient is also crucial in promoting CO2 and alkane mixing during counterdiffusion processes. These results stress the need for a paradigm shift from classical bulk flow modelling to species-based transport modelling in nanoporous media.

Yielding onset in FGM thick-walled spherical shells under thermo-mechanical loading

Based on von Mises yield criterion, a thermoelasto-plastic analysis of a thick-walled spherical shell composed of functionally graded material (FGM) subjected to internal pressure and thermal gradient is conducted in order to accurately predict the onset radius of yielding within the vessel wall. The modulus of elasticity, thermal conductivity and thermal expansion coefficients, and yield stress of FGM are assumed to follow power-law functions in radius according to Erdogan’s model. The equilibrium differential equation of the shell under thermo-mechanical loading in steady-state conduction heat transfer are derived analytically and then solved to determine through-thickness variations of the radial and circumferential stresses and radial displacement in elastic and perfectly plastic zones in the vessel wall. The presented approach leads to the definition of new formulation to predict the onset radius of yielding. Moreover, a neural network (NN) solution to reliable quantify the influence of all uncertain input parameters with respect to uncertain output parameter is utilized. The numerical results showed that for various FGM parameters and specific thermal gradient, the plastic zone can commence from inside radius, outside radius, simultaneously in both radii, or may be launched in the intermediate radius of the spherical shell wall.

Abstract 4118342: Acoustic Analysis For The Detection Of Leaflet Thrombosis After Transcatheter Aortic Valve Replacement

Introduction: Following trans-catheter aortic valve replacement (TAVR), patients may develop aortic valve leaflet thrombosis, a condition associated with an increased risk of embolic events. Currently, the diagnosis of post-TAVR leaflet thrombosis is based on echocardiography surveillance or cardiac tomography (CCT) scan, both require specialized team and equipment, and may also expose the patients to radiation and contrast. Acoustic analysis is a non-invasive reproducible method, which incorporates the recording of cardiac sounds and analyzing them via machine learning algorithms. Here, we investigated the diagnostic abilities of acoustic analysis in the detection of post-TAVR leaflet thrombosis. Methods: Using an electronic stethoscope, heart sounds were prospectively recorded at 2 time points: 24-hours and 6-months post-TAVR. CCT scan was performed 6-months following TAVR to detect leaflet thrombosis. Acoustic sounds were analyzed, using a Gaussian support vector machine (SVM) algorithm, to identify features associated with leaflet thrombosis. Results: Of 19 consecutive patients, 3 were found to have high-grade leaflet thrombosis based on CCT results. The SVM algorithm effectively classified heart sounds into "normal" and "thrombotic", with a sensitivity of 100% and specificity of 97.2%. Following anticoagulation therapy, all 3 patients showed no signs of leaflet thrombosis on follow-up CCT scans and were also classified as "normal" by the algorithm. Notably, at the time of leaflet thrombosis, Doppler echocardiographies showed normal pressure gradients across the affected valves. Conclusions: These initial results suggest that acoustic analysis, combined with machine learning algorithms, may identify post-TAVR leaflet thrombosis, providing a non-invasive, cost-effective, and radiation-free alternative to traditional diagnostic methods.

Abstract 4138417: A Novel Echocardiography Risk Score Predicted Mortality In Patients With Heart Failure With Preserved Ejection Fraction.

Introduction: Patients with heart failure with preserved ejection fraction (HFpEF) exhibit several echocardiographic abnormalities, including diastolic dysfunction, left ventricular (LV) hypertrophy, left atrial enlargement or pulmonary hypertrophy. It is not fully understood how these abnormalities are related with prognosis in HFpEF patients. Hypothesis: A combination of echocardiography parameters can predict clinical outcome in patients with HFpEF. Aims: This study aimed to develop a model to predict all-cause mortality in patients with HFpEF using echocardiography parameters. Methods: We analyzed data from 952 patients (81±9 years, 43% male) registered in the PURSUIT-HFpEF (Prospective, Multicenter, Observational Study of Patients with Heart Failure with Preserved Ejection Fraction) study, a multicenter registry of patients hospitalized for acute decompensated HFpEF. Comprehensive echocardiography was performed before discharge. Patients were randomly assigned to the derivation and validation cohorts (2:1 ratio). Stepwise model selection was performed on age, sex and 26 echocardiography parameters to identify independent predictors of mortality. These predictors were used to construct a risk model for mortality. The accuracy of the risk score was validated using time-dependent ROC curves in both the derivation cohort (n=629) and in the validation cohort (n=323). Results: During the follow-up period (720 days, IQR: 376, 1100 days), all-cause death was observed in 248 patients (26.1%). Age, sex, diastolic (DWS), E/e’ ratio, LV mass index, LV posterior wall thickness (PWth), relative wall thickness (RWT), tricuspid regurgitant pressure gradient (TRPG) were selected as independent predictors of all-cause death. The score shown in the Table was applied to each factor, and the sum of the scores was calculated as the risk score. The AUC of the risk score for predicting 1-year mortality in the derivation cohort was 0.71 and the optimal cut-off value of 4.5 provided a sensitivity and specificity of 62.8% and 69.1%, respectively. The AUC for 1-year mortality in the validation cohort was 0.67. Conclusions: The novel echocardiography score effectively predicted mortality in HFpEF. This model could be a valuable tool for risk stratification.

Abstract 4132498: Hemodynamic and Clinical Outcomes with Balloon-Expandable Valves Versus Self-Expanding Valves in Patients with Small Aortic Annulus Undergoing Transcatheter Aortic Valve Implantation: A Meta-Analysis of Randomized Controlled Trials and Propensity Score Matched Studies

Background: Transcatheter aortic valve implantation (TAVI) is thought to be more effective than surgery for patients with small aortic annulus (SAA), however, the comparative efficacy of different transcatheter heart valves (THVs) remains uncertain. The objective of this meta-analysis was to compare the effects of balloon-expandable valves (BEVs) and self-expanding valves (SEVs) on hemodynamic parameters and clinical outcomes in patients with SAA who underwent TAVI. Methods: A thorough literature search was performed across PubMed/MEDLINE, Embase, and the Cochrane Library from their inception until May 2024 to identify eligible randomized controlled trials (RCTs) and propensity-score matched (PSM) studies. Clinical outcomes were evaluated using a random-effects model to pool risk ratios (RRs) with 95% confidence intervals (CIs). Results: The analysis included 8 studies; 2 RCTs and 6 PSM studies, with a total of 2,180 patients with SAA. BEVs were associated with a smaller indexed effective orifice area (MD: -0.18, 95% CI: -0.31 to -0.05) and a higher transvalvular mean pressure gradient (MD: 5.23, 95% CI 3.44 to 7.02) than SEVs. The risk for prosthesis-patient mismatch (PPM) (RR= 1.82, 95% CI: 1.27 to 2.60) and severe PPM (RR= 2.77, 95% CI: 1.93 to 3.98) was significantly higher for patients receiving BEVs than those receiving SEVs. However, no significant difference was observed between BEVs and SEVs regarding the risk of paravalvular leak (RR= 0.98, 95% CI: 0.57 to 1.69) and the permanent pacemaker implantation (RR= 0.78, 95% CI: 0.50 to 1.23). Although patients receiving BEVs showed a slightly lower risk of major bleeding events (RR= 0.69, 95% CI: 0.49 to 0.99), BEVs were associated with a significantly increased risk of 1-year cardiovascular mortality (RR= 1.61, 95% CI: 1.05 to 2.47) compared to those receiving SEVs. However, no significant differences were observed between BEVs and SEVs regarding 30-day all-cause mortality (RR= 1.19, 95% CI: 0.57 to 2.49), 1-year all-cause mortality (RR= 1.17, 95% CI: 0.89 to 1.53), stroke rates (RR= 0.83, 95% CI: 0.52 to 1.31) and any vascular complication (RR= 1.13, 95% CI: 0.72 to 1.75). Conclusion: In patients with SAA, SEVs showed reduced risks of PPM and severe PPM compared to BEVs, along with a larger indexed effective orifice area. Moreover, SEVs were associated with a lower risk of 1-year cardiovascular mortality.

Abstract 4138624: Looking Beyond Respirophasic Ventricular Interdependence: A Case Report of Constrictive Pericarditis Masquerading as Cirrhosis

Case Presentation: A 67-year-old man with recurrent pleural effusions and concern for cirrhosis was referred for liver transplant. Pleural fluid was transudative by Light’s criteria with a high total protein level of 3.5 g/dL, which made hepatic hydrothorax unlikely. Liver biopsy confirmed congestive hepatopathy without advanced fibrosis. Transthoracic echocardiogram showed left ventricular (LV) ejection fraction 55%, right ventricular (RV) systolic pressure 35 mmHg, normal mitral annular tissue doppler velocities, and early diastolic septal bounce. Right and left heart catheterization showed prominent X and Y descent, elevated and equalized diastolic pressures, but no respiratory discordance in the LV-RV pressure gradient. As etiology of these findings were unclear, he underwent aggressive diuresis and hemodialysis, but repeat right heart catheterization showed persistently elevated right and left filling pressures. Cardiac MRI had no evidence of myocardial or pericardial inflammation/edema but showed pericardial thickening (7.9 mm) and septal bounce. There was no inspiratory septal shift, but the large pleural effusion appeared to limit diaphragm excursion. Given lack of respirophasic ventricular interdependence and thickened pericardium on MRI, CT was ordered, showing pericardial calcifications. Diagnosis of constrictive pericarditis was made, and patient underwent complete pericardiectomy. Pathology confirmed calcified and thick pericardium without acute inflammation. Post-operatively, patient developed RV failure, but recovered with inotrope support and was discharged with improvement in congestive symptoms. Discussion: Constrictive pericarditis classically exhibits respirophasic ventricular interdependence, but large pleural effusions may decrease respiratory variation in intrathoracic pressures, blunting this response. Normal mitral annulus tissue doppler velocities and lack of infiltrative process on cardiac MRI made restrictive cardiomyopathy unlikely. In the absence of respirophasic changes on multimodality testing, constriction can be diagnosed with other supportive features such as diastolic septal bounce, rapid Y descent, diastolic pressure equalization, and pericardial thickening and calcifications.

Abstract 4140192: Time Trends in Outcomes of Trans-Catheter Aortic Valve Replacement with Balloon-expanding Versus Self-expanding Valves: A Meta-analysis of Randomized Controlled Trials

Background: The research on the outcomes of transcatheter aortic valve replacement with balloon-expandable valves (BEV) and self-expanding valves (SEV) are limited. Hypothesis: This study aims to compare the clinical and hemodynamic outcomes of BEV and SEV at short-term (30 days), mid-term (1 year), and long-term (&gt;1 year) endpoints. Methods: PubMed, Embase, Scopus, and Cochrane Library databases were searched up to April 25, 2024, for randomized controlled trials (RCTs). Random-effect model (DerSimonian–Laird method) was used to pool the risk ratios (RR), mean differences (MD) and 95% confidence interval (CI) for binary and continuous outcomes, respectively. Results: A total of 11 RCTs comprising 4,325 patients (2,295 BEV, 2,030 SEV) were included. At short-term, the risk of cardiovascular (RR: 0.56, 95% CI: 0.36-0.87) and all-cause mortality (RR: 0.54, 95% CI: 0.35-0.81) were lower in the BEV group. However, no differences were noted between the two treatment modalities in longer follow-ups despite the lower risk of moderate to severe paravalvular leak (PVL) among BEV patients. The risk of stroke was comparable between two groups across all three follow-up endpoints, albeit a limited number of studies suggesting the BEV group showed a greater risk of clinical valve thrombosis in mid-term and long-term assessments. The need for permanent pacemaker implantation was lower in BEV arm in short-term (RR: 0.56, 95% CI: 0.37-0.87) and mid-term (RR: 0.78, 95% CI: 0.64-0.94). Yet, this difference was not observed in long-term follow-ups. Conversely, the SEV group had a larger effective orifice area with lower mean transvalvular pressure gradient from short-term (MD: 0.17, 95% CI: 0.07-0.26 and MD: 3.71, 95% CI: 2.64-4.78, respectively) to long-term (MD: 0.25, 95% CI: 0.17-0.32 and MD: 3.73, 95% CI: 3.19-4.27, respectively) periods. Conclusions: BEV is associated with reduced risk of clinical outcomes at short-term; however, most differences diminish in longer evaluations, except for moderate to severe PVL. Conversely, SEV is linked to better hemodynamic outcomes and a lower risk of clinical valve thrombosis across all follow-up durations.