Low Strain Research Articles

Comparison of Mechanical Behaviour of Prototype UFREI and PB-FREI Under Cyclic Loading

ABSTRACT An experimental study is carried out on prototype UFREI and PB-FREI to compare their hysteretic responses under combined vertical load and cyclic displacement history. Further, 3D finite element analysis of UFREI and PB-FREI is carried out up to shear strain level of 150%. Comparison of numerical responses of UFREI and PB-FREI under lateral strain of up to 150% is also carried out. It is observed that the stress and strain contours in elastomer layers are similar for UFREI and PB-FREI for lower strain level. However, higher compressive stress is observed in the central region of PB-FREI at higher strain level.

Statistical Characteristics of Strong Earthquake Sequence in Northeastern Tibetan Plateau

As the forefront of inland extension on the Indian plate, the northeastern Tibetan Plateau, marked by low strain rates and high stress levels, is one of the regions with the highest seismic risk. Analyzing seismicity through statistical methods holds significant scientific value for understanding tectonic conditions and assessing earthquake risk. However, seismic monitoring capacity in this region remains limited, and earthquake frequency is low, complicating efforts to improve earthquake catalogs through enhanced identification and localization techniques. Bi-scale empirical probability integral transformation (BEPIT), a statistical method, can address these data gaps by supplementing missing events shortly after moderate to large earthquakes, resulting in a more reliable statistical data set. In this study, we analyzed six earthquake sequences with magnitudes of MS ≥ 6.0 that occurred in northeastern Tibet since 2009, following the upgrade of the regional seismic network. Using BEPIT, we supplemented short-term missing aftershocks in these sequences, creating a more complete earthquake catalog. ETAS model parameters and b values for these sequences were then estimated using maximum likelihood methods to analyze parameter variability across sequences. The findings indicate that the b value is low, reflecting relatively high regional stress. The background seismicity rate is very low, with most mainshocks in these sequences being background events rather than foreshock-driven events. The p-parameter of the ETAS model is high, indicating that aftershocks decay relatively quickly, while the α-parameter is also elevated, suggesting that aftershocks are predominantly induced by the mainshock. These conditions suggest that earthquake prediction in this region is challenging through seismicity analysis alone, and alternative approaches integrating non-seismic data, such as electromagnetic and fluid monitoring, may offer more viable solutions. This study provides valuable insights into earthquake forecasting in the northeastern Tibetan Plateau.

Effect of anisotropic Peierls barrier on the evolution of discrete dislocation networks in Ni

Abstract Over low and intermediate strain rates, plasticity in face centered cubic (FCC) metals is governed by the glide of dislocations, which manifest as complex networks that evolve with strain. Considering the elastic anisotropy of FCC metals, the characteristics of dislocation motion are also anisotropic (i.e. dislocation character angle-dependent), which is expected to notably influence the overall evolution of the dislocation network, and consequently, the plastic response of these materials. The aggregate influence of the anisotropy in the Peierls stress on the mechanical response of single crystal Ni was investigated in the present work using discrete dislocation dynamics simulations. Twenty initial dislocation networks, differing in their configuration and dislocation density, were deformed under uniaxial tension up to at least 0.9% strain, and the analysis of character-dependent dynamics showed a suppression of plasticity only for segments of nearly screw character. While the increased screw component of the Peierls stress raised the initial strain hardening rate, it also resulted in longer dislocation segments overall, contrary to the reasoning that longer pinned segments exhibit a lower resistance to motion and might give a weaker response. A non-linear superposition principle is demonstrated to predict the hardening reasonably well, considering the cumulative effects of forest and Peierls stress-related strengthening. Further analysis of the network topology revealed a tendency to maintain connectivity over the course of deformation for those networks simulated using an unequal Peierls stress. The general increases in hardening rate and network connectivity contrast with the localized reduction of dislocation motion, which occurred mainly for segments of nearly screw-type character.

Mechanism and Structural Defects of Zinc Film Deposited on a Copper Substrate: A Study via Molecular Dynamics Simulations

Epitaxial growth can be used to guide the controllable growth of one metal on the surface of another substrate by matching the interface lattice, thus improving the dendrite tendency of metal growth. The atomic arrangement of the Cu (111) crystal plane of the FCC structure is similar to that of the Zn (0002) crystal plane of the HCP structure, which is theoretically expected to promote the heterogeneous epitaxial nucleation growth of metal zinc under low strain. In this paper, the molecular dynamics method is used to simulate the atomic process of zinc film growth on the Cu (111) surface. It is found that the behavior of zinc-adsorbed atoms on the substrate surface conforms to the epitaxial growth mode. The close-packed structure grown along the (0002) direction of the layered clusters is tiled on the Cu (111) surface, forming a highly ordered low-lattice-mismatch interface. When a large area of layered zinc clusters cover the substrate, the growth mode will change from heteroepitaxial growth to homoepitaxial growth of Zn atoms on the zinc film, forming a lamellar distribution composed of FCC and HCP structure grains. Polycrystalline zinc film with a planar structure with a (0002) surface preferred a crystal plane. The increase in incident energy is helpful in improving the quality of zinc films, while the deposition rate, corresponding to the deposition temperature and electrolyte ion concentration, has no significant effect on the surface morphology and crystal structure of single metal films. In summary, the atomic arrangement of the Cu (111) surface has a strong guiding effect on the atomic ordered arrangement in the zinc film crystal, which is suitable for the epitaxial deposition of the substrate to induce the ordered growth of the Zn (0002) crystal plane.

Characterizing Six Percolation Cases in Flexible Electronic Composites: A Monte Carlo-Based 3D Compressive Percolation Model for Wearable Pressure Sensors

This study employs a Monte Carlo-based 3D compressive percolation model to systematically analyze the electrical behavior of flexible electronic composites under compressive deformation. By simulating the spatial distribution and connectivity of conductive particles, this study identifies six distinct percolation cases, each describing a unique connectivity evolution under strain. The model reveals that excessive initial connectivity leads to saturation effects, reducing sensitivity, while a high Poisson’s ratio (≥0.3) causes connectivity loss due to shear plane expansion. Notably, asymmetric particle shapes, such as cylinders and rectangles, exhibit superior percolation behavior, forming infinite clusters at lower strain thresholds (~0.4) compared to spherical particles (~0.5). Monte Carlo simulations with 3000 particles validate these findings, showing consistent trends in percolation behavior across different deformation states. By classifying and quantifying these six connectivity scenarios, this research provides a structured framework for optimizing flexible sensor designs, ensuring an optimal balance between conductivity and sensitivity. These findings contribute to advancing flexible electronics, particularly in wearable health monitoring, robotics, and smart textiles.

A lightweight TiZrV0.5Nb0.3Al0.2 refractory high-entropy alloys with enhanced strength and ductility at low and high strains loading

A lightweight TiZrV0.5Nb0.3Al0.2 refractory high-entropy alloys with enhanced strength and ductility at low and high strains loading

Comparative Transcriptomic Responses Directed Towards Reporter Metabolic Routes of Mucor circinelloides WJ11 for Growth Adaptation and Lipid Overproduction

Research into the cellular metabolic adaptations of Mucor circinelloides has gained significant interest due to its capability for lipid production, which has critical industrial applications. To address the regulatory mechanisms at the systems level, this study aimed to explore the global metabolic responses associated with lipid production in high and low lipid-producing strains of M. circinelloides, WJ11 and CBS277.49, respectively, through comparative transcriptome analysis and genome-scale model-driven analysis. The transcriptome analysis of expressed genes in M. circinelloides WJ11 (6398 genes), and CBS277.49 (6008 genes) were analyzed and compared. The results revealed 2811 significantly differentially expressed genes and highlighted strain-dependent differences in growth behavior and lipid production of M. circinelloides at the fast-growing stage, driven by transcriptional regulation across key metabolic pathways. Through genome-scale model-driven analysis, we identified 20 significant reporter metabolites that provide insights into the mechanisms employed by the WJ11 strain to optimize growth for lipid production in the subsequent lipid-accumulating stage. These interplay mechanisms are primarily involved in glycolysis, the TCA cycle, leucine metabolism, energy metabolism, and one-carbon metabolism towards lipid metabolism. These findings provide valuable insights into the regulatory mechanisms underlying lipid production in Mucor and highlight potential pathways for genetic and physiological optimization in high lipid-producing strains like WJ11. This research advances our understanding of how metabolic networks are interconnected and how they can be leveraged for more efficient lipid overproduction.

Virulence expression difference to intestinal cells of different pathogenic Listeria monocytogenes contaminating sausages after simulated digestive tract.

This study investigated the difference in survival among Listeria monocytogenes (LM) 10403S (highly pathogenic strain) and M7 (low pathogenic strain) in sausage under a simulated digestive environment, and established intestinal organoids and macrophages co-culture model to further explore the virulence expression difference to intestinal cells between LM 10403S and M7 after in vitro gastrointestinal digestion. Results showed that, compared with LM M7, LM 10403S exhibited a high survival rate during in vitro digestion, which may be due to the increased expression of stress response-related genes. In addition, the expression of virulence genes in LM 10403S was significantly higher than in LM M7 under the gastrointestinal environment. Furthermore, in the intestinal organoids and macrophages co-culture model infected by LM 10403S and M7 after in vitro gastrointestinal digestion, results showed that, compared with the LM M7 group, the LM 10403S group had significantly lower budding rate and significantly higher mortality of organoids. Also, the significantly increased LDH release and inflammatory factors (TNF-α and IL-1β) in the LM 10403S group were observed, and the main virulence genes (iap, inlA, inlB, actA, hly, plcA, and plcB) of 10403S were significantly highly expressed than LM M7 during the cell infection. These results reflected that the reason for the different pathogenicity between LM 10403S and M7 may be due to the high tolerance and the expression of virulence genes than LM M7 during gastrointestinal digestion and cell infection, which would be expected to provide a better understanding of the infection mechanisms among different pathogenic strains of L. monocytogenes in food.

Progress in the application of cardiac magnetic resonance to predict recurrence of atrial fibrillation after catheter ablation: A systematic review and meta-analysis.

This systematic review and meta-analysis aimed to assess changes in left atrial structure and function at baseline and after catheter ablation and their association with atrial fibrillation recurrence using cardiac magnetic resonance imaging (MRI). As of June 2024, a total of 3086 articles have been obtained through searching PubMed, Embase, and Cochrane databases. Standard mean differences and 95% confidence intervals were used to examine structural and functional changes of left atrium after catheter ablation and their relationship with recurrence of atrial fibrillation. A total of 13 prospective cohort studies were included in the analysis. Decreased left atrial emptying capacity is seen in the short term after catheter ablation, and structural changes in the left atrium are seen in the long term (EFActive: SMD, 1.23, 95% CI, 1.10-2.36, p<0.05; EFTotal: SMD, 0.83, 95% CI, 0.02-1.64, p<0.05; MinLAV: SMD, 0.30, 95% CI, 0.01-0.59, p<0.05). Decrease in left atrial volume after catheter ablationis positively associated with the risk of recurrence of atrial fibrillation. (MaxLAV: SMD, 1.27, 95% CI, 0.05, 2.49, p<0.05; MaxLAVi: SMD, 0.48, 95% CI, 0.05,0.9, p<0.05;MinLAVi: SMD, 0.78, 95% CI, 0.39,1.16, p<0.05). The larger the left atrial volume and the lower the emptying and strain function, the greater the likelihood of recurrence of atrial fibrillation following catheter ablation, (MaxLAV: SMD, 0.38, 95% CI, 0.18,0.59, p<0.05;MinLAV: SMD, 0.83,95% CI, 0.41,1.24, p<0.05; MaxLAVi: SMD, 0.35, 95% CI, 0.21,0.50, p<0.05;MinLAVi: SMD, 0.62, 95% CI, 0.47,0.78, p<0.05; EFPassive: SMD, -0.57, 95% CI, -0.78, -0.37, p<0.05; EFActive: SMD, -0.62, 95% CI, -1.08, -0.15, P<0.05; EFTotal: SMD, -0.70, 95% CI, -0.97, -0.44, P<0.05; ℇCT: SMD, -0.61, 95% CI, -0.90, -0.32, p<0.05; PLAS: SMD, -1.22, 95% CI, -1.87, -0.57, p<0.05; ℇR: SMD, -0.50, 95% CI, -0.79, -0.21, p<0.05; PLAS: SMD, -1.22, 95% CI, -1.87, -0.57, p<0.05). Short-term left atrial functional impairment can be observed after catheter ablation, while long-term reduction in left atrial volume can be seen. Changes in left atrial volume are likely to lead to the recurrence of atrial fibrillation, while alterations in left atrial function help maintain sinus rhythm. Larger left atrial volume and lower emptying and strain function at baseline assessment by cardiac magnetic resonance are more likely to lead to recurrence of atrial fibrillation after catheter ablation, which may be useful to identify those for whom catheter ablation has reduced success or for whom more aggressive ablation or medications may be useful.

Higher Aircraft Noise Exposure Is Linked to Worse Heart Structure and Function by Cardiovascular MRI.

Aircraft noise is a growing concern for communities living near airports. This study aimed to explore the impact of aircraft noise on heart structure and function. Nighttime aircraft noise levels (Lnight) and weighted 24-hour day-evening-night aircraft noise levels (Lden) were provided by the UK Civil Aviation Authority for 2011. Health data came from UK Biobank (UKB) participants living near 4 UK major airports (London Heathrow, London Gatwick, Manchester, and Birmingham) who had cardiovascular magnetic resonance (CMR) imaging starting from 2014 and self-reported no hearing difficulties. Generalized linear models investigated the associations between aircraft noise exposure and CMR metrics (derived using a validated convolutional neural network to ensure consistent image segmentations), after adjustment for demographic, socioeconomic, lifestyle, and environmental confounders. Mediation by cardiovascular risk factors was also explored. Downstream associations between CMR metrics and major adverse cardiac events (MACE) were tested in a separate prospective UKB subcohort (n = 21,360), to understand the potential clinical impact of any noise-associated heart remodeling. Of the 3,635 UKB participants included, 3% experienced higher Lnight (≥45 dB) and 8% higher Lden (≥50 dB). Participants exposed to higher Lnight had 7% (95%CI: 4%-10%) greater left ventricular (LV) mass and 4% (95%CI: 2%-5%) thicker LV walls with a normal septal-to-lateral wall thickness ratio. This concentric LV remodeling is relevant because a 7% greater LV mass associates with a 32% greater risk of MACE. They also had worse LV myocardial dynamics (eg, an 8% [95%CI: 4%-12%] lower global circumferential strain which associates with a 27% higher risk of MACE). Overall, a hypothetical individual experiencing the typical CMR abnormalities associated with a higher Lnight exposure may have a 4 times higher risk of MACE. Findings were clearest for Lnight but were broadly similar in analyses using Lden. Body mass index and hypertension appeared to mediate 10% to 50% of the observed associations. Participants who did not move home during follow-up and were continuously exposed to higher aircraft noise levels had the worst CMR phenotype. Higher aircraft noise exposure associates with adverse LV remodeling, potentially due to noise increasing the risk of obesity and hypertension. Findings are consistent with the existing literature on aircraft noise and cardiovascular disease, and need to be considered by policymakers and the aviation industry.

Influence of asymmetric rolling paths on the microstructure, texture, mechanical behavior, and electrical conductivity of electrolytic tough-pitch copper

In this work, the influence of asymmetric rolling paths on the microstructure, texture, mechanical behavior, and electrical conductivity of electrolytic tough-pitch copper was studied. Four different asymmetric rolling paths including unidirectional (UD), rolling (RD), transverse (TD), and normal (ND) with a thickness reduction of 90% were applied. Based on simulation results, the uniformity of strain distribution in the UD path was less than the other paths, the RD and ND paths had a better distribution of strain along the thickness, and the TD path exhibited the best strain distribution. Because of this, the TD, ND, and RD samples revealed a better distribution of copper oxide particles compared to the UD sample. The homogeneity of texture through the sheet thickness for the RD, TD, and ND paths was more than that for the UD path due to the uniform strain distribution. Unlike the other samples, the UD sample exhibited {001}〈110〉 Rotated Cube and {001}〈100〉 Cube orientations in the areas close to the surface due to the formation of severe accumulated strain. The maximum yield strength (405.5 MPa) and tensile strength (419.0 MPa) belonged to the RD sample. The TD sample showed a lower strain hardening rate as a result of easier cross-slip. The highest electrical conductivity (85.2 %IACS) belonged to the TD sample due to its lower dislocation density. The presence of θ-fiber and γ-fiber improved the electron conductivity of copper.

Priming of ash saplings with a low virulent Hymenoscyphus fraxineus strain as a possible disease control approach for reducing symptoms of ash dieback

Ash dieback is a tree disease caused by the fungal pathogen Hymenoscyphus fraxineus. Since its introduction into Europe, it has caused widespread and significant losses of the European ash, Fraxinus excelsior. Inoculations of F. excelsior with a low virulent H. fraxineus isolate were assessed as a promising method for reducing symptoms associated with ash dieback, presumably by triggering systemic induced resistance. Two strains of H. fraxineus were chosen based on observations of high and low in planta virulence. Crude extracts obtained from cultures of the highly virulent strain were more phytotoxic in a leaf puncture assay than ones obtained from the low virulent strain. UHPLC-DAD-MS/MS data identified the phytotoxin viridiol and the potential phytotoxin hyfraxin A in both cultures. However, the production of these compounds in vitro did not correspond with virulence in planta. To test the effects of priming, saplings of F. excelsior were first inoculated with the low virulent strain and subsequently with the highly virulent strain. On average, necrosis expansion on the stems was reduced by 53% in primed saplings at the end of the 14-week monitoring period, thus providing proof of the priming concept. These results contribute to our understanding of a possible integrated biological disease control approach for increasing resistance in saplings and reducing potential damages associated with pathogens, particularly during nursery propagation, out-planting and through the establishment phase. We discuss results in the context of relevant literature and summarise the limited availability of literature on priming and underlying principles in trees.

Influence of different polymeric materials of implant and attachment on stress distribution in implant-supported overdentures: a three-dimensional finite element study

PurposeInvestigating high performance thermoplastic polymers as substitutes to titanium alloy, in fabrication of implants and attachments to support mandibular overdenture, aiming to overcome stress shielding effect of titanium alloy implants.Aim of studyAssessment of stress distribution in polymeric prosthetic components and bone around polymeric implants, in case of implant-supported mandibular overdenture.Materials and methods3D finite element model was established for mandibular overdenture, supported bilaterally by two implants at canine region, and retained by two ball attachments. Linear static stress analysis was carried out by ANSYS 2020 R1. Three identical models were created with different materials for modeling of prosthetic components (implant body, gingival former, ball attachment and matrix). The Monolithic principle was applied as the same material was used in modelling all the prosthetic components in each model (Titanium alloy grade V, poly-ether-ether-ketone (PEEK) and poly-ether-ketone-ketone (PEKK)). Simultaneous Force application of 60 N was carried out bilaterally at the first molar occlusal surface area using 3 runs (vertical, lateral and oblique).ResultsPEEK and PEKK prosthetic components exhibited the highest total deformation and critical Maximum von Mises stresses values in implant body and gingival former under lateral and oblique loads. The stress values approached the fatigue limit of both polymeric materials presenting low factor of safety (< 1.5). The Peri-implant cortical bone in case of PEEK and PEKK showed nearly double maximum principal stresses compared with the titanium model. Conversely, Maximum von Mises stresses in spongy bone were lower in polymeric models than those of titanium ones. Additionally maximum equivalent strain values in spongy peri-implant bone of polymeric models were also lower than those of titanium model.ConclusionCritical high stresses were induced in implant body and gingival former under oblique or lateral loadings, accordingly, fatigue failure of both PEEK and PEKK polymer prosthetic elements was estimated due to low factor of safety. Both PEEK and PEKK Polymer models offered no advantage over titanium one regarding stress shielding effect, due to low stress and strain values generated at spongy peri-implant bone in polymer models.

Exposure to prenatal hypoxia impairs the function and structure of the carotid arteries in the adult offspring.

Prenatal hypoxia, a common pregnancy complication, can lead to vascular dysfunction, thereby increasing the risk of cardiovascular disease in the adult offspring. Carotid arteries are responsible for the majority of the blood flow to the brain/head, and carotid artery dysfunction is associated with life-threating cardiovascular events, such as stroke. However, whether prenatal hypoxia exposure impacts the function of the carotid arteries in the adult offspring is not known. We hypothesize that prenatal hypoxia impairs carotid artery function in the adult male and female offspring. Sprague Dawley rats were exposed to normoxia (21% O2) or hypoxia (11% O2) from gestational day (GD) 15 to 21 (term=22 days; n=9-11/group). Carotid arteries were isolated from the 4-month-old adult male and female offspring. Vasoconstrictor and vasodilatory properties were assessed by wire myography, and biomechanical properties (myogenic tone, circumferential stress and strain) by pressure myography. Collagen deposition (Masson's trichrome stain) and elastin density (Verhoeff stain) were measured in carotid artery cryosections. Prenatal hypoxia did not impact vasoconstriction or vasorelaxation responses in carotid arteries from both offspring. However, in males, prenatal hypoxia reduced carotid artery myogenic tone development and increased circumferential strain, which coincided with a lower collagen deposition and higher elastin density. In females, prenatal hypoxia tended to lower carotid artery circumferential strain (i.e., increased stiffness), without differences in myogenic tone or collagen/elastin density. Altogether, these data show that prenatal hypoxia exposure affects the carotid arteries of the adult offspring in a sex-specific manner, which may impact the blood flow regulation to the brain.

High sensitivity flexible strain sensor for motion monitoring based on MWCNT@MXene and silicone rubber

Research on flexible strain sensors has grown rapidly and is widely applied in the fields of soft robotics, body motion detection, wearable sensors, health monitoring, and sports. In this study, MXene was successfully synthesized in powder form and combined with multi-walled carbon nanotube (MWCNT) to develop MWCNT@MXene conductive network-based flexible strain sensors with silicone rubber (SR) substrate. Combining MWCNTs with MXene as a conductive material has been shown to significantly improve the sensor performance, due to MXene’s high conductivity properties that strengthen the MWCNT conductive pathway, increase sensitivity, and improve sensor stability. The sensor is fabricated by a sandwich method consisting of three layers, which enables more accurate and reliable detection of strain changes. The main innovation of this research is the utilization of MWCNT@MXene as a conductive material that optimizes the performance of flexible strain sensors, overcomes the limitations of previous materials, and makes it a more effective solution for long-term applications. Furthermore, the sensor was evaluated to test its performance through sensitivity, linearity, response time, and durability tests. The results showed that the sensor exhibited excellent performance with a high sensitivity of 39.97 over a strain range of 0-100% and excellent linearity (0.99) over a strain of 0–50%. The sensor also has a fast response time of about 70 ms, it also has good stability during low (1–5%) and high (20–100%) strain cycle testing and can withstand up to 1200 loading and unloading cycles. In addition, the sensor effectively detects a wide range of body movements, including finger, wrist and knee movements. These findings show that the electromechanical properties of strain sensors are significantly improved through the use of MWCNT@MXene as a conductive material, so these sensors are considered a promising solution for applications in wearables and body motion monitoring.

Clinical impact of right atrium function on tricuspid regurgitation

Abstract Background tricuspid regurgitation (TR) is frequent, and its related systemic venous congestion is associated with mortality. Purpose This study aims to evaluate the role of right atrial (RA) function, measured using the strain technique, on the medium- to long-term clinical effects of tricuspid regurgitation (TR). Our primary objective was to analyze the impact of RA function, measured at baseline, on a composite endpoint consisting of death and/or hospitalization for predominantly right-sided heart failure. The secondary endpoints are hospitalizations, worsening of renal function, and an increase in diuretic dosage (DD). Methods We performed a single center, prospective, observational study regarding adult patients with tricuspid regurgitation and measurable effective regurgitant orifice area (EROA) and a state of hemodynamic stability that underwent a complete echocardiography and full cardiologic evaluation in our Institution, from January 2020 to February 2023. Those patients with acute HF, poor quality imaging, previous repair or prosthetic replacement of the tricuspid valve, and severe renal or hepatic insufficiency were excluded. Patients were assessed clinically at each follow up. Results 134 patients were included (females 62%, mean age 73 ± 13 years old). Median follow up was 23,5 months (12 - 34 months). TR was functional in 87% of cases and was more than moderate in 52% of cases. Mean RA strain was 18,7 ± 11,2%, and divided patients in low strain (LS) and high strain (HS). HS was associated with lower increase and frequently a decrease in DD (-5,5 ± 44,7 mg vs 20,8 ± 63,2 mg, p = 0,009) but no echocardiographic variable independently predicted an increase in DD. Patients with worsening renal function had significantly lower RA (16.7 ± 10.6% vs 20.7 ± 10.9%, p 0.042). LS independently predicted a worsening renal function (OR 3,07; 95% CI 1,026-9,2). RA strain was significantly lower in hospitalized patients (13.1 ± 8 vs 20.3 ± 11.4, p&amp;lt;0.001). Cox regression analysis showed a LS to be an independent predictor of the composite endpoint (adjusted HR 3.1, 95% CI 1.101 – 8.74) correcting for other clinical and echocardiographic variables. ROC curve analysis showed an RA strain cut-off of 18.5% to have a sensitivity of 79% and specificity of 56% in predicting the combined endpoint. Conclusions RA strain is associated with DD and LS patients have higher DD at follow up. RA strain is an independent predictor of worsening renal function. RA function measured by strain is an independent predictor of the composite endpoint of death and/or hospitalization.

Utility of left atrial strain in characterizing patients with reablated atrial fibrillation

Abstract Introduction and Objectives Atrial fibrillation (AF) is a highly prevalent condition, with projections indicating it will increase in the future. Various ablation techniques exist to try to eliminate the arrhythmia, but the problem of recurrences and the need for reinterventions are not uncommon. We need markers to predict which patients will benefit from these procedures and which will recur despite our efforts. Atrial strain techniques have emerged as a novel tool in assessing the function and degree of atrial fibrosis, which could improve patient selection and increase the success of procedures. Methods A retrospective analysis was conducted, including adult patients who had undergone echocardiography at our center during the years 2023-2024. A total of 59 healthy patients with no history of cardiovascular disease, labeled as "normal studies" by the examiner, served as the control group, and another group of 47 patients with recurrent AF with at least two ablation procedures were included. Various left atrial strain values (Reservoir, Conduit, and Pump) of each patient were analyzed. Descriptive statistics were calculated for each group and segment, and the Mann-Whitney U test was used to compare the groups. Results Patients with reablated AF showed significantly lower absolute strain values compared to normal patients in all three analyzed varieties (Reservoir, Conduit, and Pump) with p&amp;lt;0.01 for all comparisons. The mean strain in the control group was 41.80 for reservoir strain, -24.01 for conduit strain, and -17.07 for pump strain; while the mean in the AF group was 17.42, -11.72, and -6.33, respectively. Conclusions We found significant differences in left atrial strain values between normal patients and patients with reablated AF. These findings suggest that left atrial strain could be useful in selecting patients for AF ablation procedures, as those more prone to recurrence exhibit lower absolute strain values, indicating a higher degree of atrial fibrosis where anomalous circuits may establish and perpetuate the arrhythmia over time. Normal Vs Atrial fibrillation

Pursuing ventricular-arterial coupling: a comparison of cardiac magnetic resonance right ventricular strain analysis and novel echo-derived indexes of right ventricular myocardial work

Abstract Introduction End-systolic to arterial elastance ratio (Ees/Ea) represents right ventricular-arterial coupling (RVAC) and is the gold standard for measuring right ventricular (RV) function However, this method is time-consuming and not always readily available. A simplified approach is using the stroke volume (SV) to end-systolic volume (ESV) ratio, which has shown prognostic relevance in pts with PH, with a cut-off value of 0.5. Cardiac magnetic resonance (CMR) measurements of volumetric data allow the assessment of this ratio. CMR strain analysis has also emerged as a technique to detect subtle changes in RV function, and, recently, right ventricular myocardial work (RVMW) assessed by transthoracic echocardiography (TTE) allows the study of RV pressure-strain loops. The association between indexes of RVMW and CMR derived parameters has not yet been extensively studied, namely in pre-capillary PH population. Objectives To evaluate the relationship between the SV/ESV ratio and CMR-derived RV strain and TTE-derived RVMW in a cohort of pts with group I and group IV PH. Methods Thirteen consecutive precapillary PH pts underwent CMR, TTE and right heart catheterization prospectively. CMR feature-tracking was used to track tissue voxel motion in short and long-axis cine images, in order to derive myocardial strain. In TTE, dedicated software for left ventricle myocardial work was used for the RV. Results 69% of pts included were women, mean age 67. The average of mean PAP was 35 mmHg (± 13.5) and PVR was 4.8 WU (± 4.9). SV/ESV ratio significantly correlated with RV ejection fraction (EF) (r = 0.888, p &amp;lt; 0.001) and circumferential peak systolic (CPS) strain (r = 0.538, p = 0.037), but not with longitudinal peak systolic (LPS) strain (p = 0.571). As for TTE-derived RVMW, SV/ESV ratio demonstrated significant correlations with RVGWI (r = 0.580, p = 0.038) and RVGCW (r = 0.654, p = 0.015) but not with RVGWW (p = 0.780) nor RVGWE (p = 0.364). Significant correlations were found between RVEF and CPS strain (r = 0.690, p = 0.009), RVEF and RVGCW (r = - 0.592, p = 0.033) and between CPS strain and RVGWI (r = 0.620, p = 0.024) and RVGCW (r = 0.718, p = 0.006). 38,5% of pts had SV/ESV ratio &amp;lt; 0.5. These pts had lower RVEF (48 ± 7.1 vs 61 ± 5.5, p = 0.004), lower CPS strain (-10.9 ± 3.0 vs -15.8 ± 2.9, p = 0.015) but higher RVGWI (828 ± 167.4 vs 526 ± 192.0, p = 0.015) and RVGCW (1061 ± 228.5 vs 698 ± 141.0, p = 0.004) compared to pts with SV/ESV &amp;gt; 0.5. LPS strain, RVGWW and RVGWE did not showed statistically differences between groups. Conclusion SV/ESV ratio correlated with both CMR-derived CPS strain and TTE-derived RVMW. Pts with a lower SV/ESV ratio had lower circumferential strain but higher work indices, suggesting potential compensatory mechanisms, where increased work may not translate to efficient pumping. Further studies with larger cohorts are warranted to validate these parameters and establish relation with outcomes. Figure 1 Figure 2

Speckle tracking echocardiography has an additive value to differentiate pulmonary hypertension associated with left heart or lung diseases in patients presenting with dyspnoea

Abstract Background The diagnostic pathway of pulmonary hypertension (PH) is complex and requires several parameters. Differential diagnosis between left heart disease (group 2) and pulmonary disease (group 3) as PH etiology is also challenging. The latest European guidelines recommend a comprehensive echocardiographic evaluation for suspected PH, and the use of several basic echocardiographic indices to assess cardiac etiology of PH. Speckle tracking echocardiography (STE) has emerged as a more sensitive technique to evaluate myocardial performance in different clinical settings and is recommended for the diagnosis of HFpEF. Purpose Our ai was to assess the potential value of STE to predict left heart disease in patients presenting with dyspnoea and PH. Methods Consecutive outpatients with dyspnoea with efforts and subsequent diagnosis of PH were retrospectively enrolled. Inclusion criteria were New York heart association (NYHA) class≥II, LV ejection fraction≥50%, echocardiographic evidence of systolic pulmonary artery pressure≥35 mmHg and tricuspid regurgitant velocity≥2.8 ms, known diagnosis of PH with relative etiology (heart failure with preserved ejection fraction, HFpEF or lung diseases i.e. sarcoidosis, idiopathic pulmonary fibrosis, chronic obstructive lung disease). Patients underwent clinical, biohumoral and echocardiographic evaluation, STE was performed offline. Primary endpoint was the prediction of HFpEF. Results Overall, 145 patients were enrolled (80 with HFpEF, 65 with lung disease). Mean age was 75±12 years, 53% were female. Patients with HFpEF were older (77±10 vs. 68±14 years, p&amp;lt;0.0001) and had higher LA volume (93±37 vs. 64±31 ml, p&amp;lt;0.0001), E/E’ by tissue Doppler imaging (TDI) (15±5 vs. 9±3, p&amp;lt;0.0001), mitral regurgitation (MR) grading (p=0.002), lower tricuspid regurgitation (TR) grading (p=0.004). Regarding STE, patients with HFpEF had lower peak atrial longitudinal strain (PALS) (15 ± 8 vs. 24 ± 11%, p&amp;lt;0.0001) and LV global longitudinal strain (-13 ± 9 vs. -17 ± 6%, p=0.009). LA stiffness, calculated as the ratio between E/E’ and PALS, an index of LA dysfunction and fibrosis, was higher in patients with HFpEF (median LA stiffness = 1.09 [CI = 0.64-1.73] 0. Vs.0.35 [CI = 0.20-0.59], p&amp;lt;0.0001). With ROC curves, both E/E’ and global PALS provided a good prediction for HFpEF (AUC 0.73 and 0.79 respectively), but LA stiffness significantly enhanced the predictive power (AUC = 0.83) with an optimal cutoff value ≥0.53. With multivariate analysis including age, LA volume, LV GLS, LA stiffness, mitral and tricuspid regurgitation grade, LA stiffness≥0.53 (RR = 19.14, CI 5.86-62.55) was the only independent predictor of HFpEF in our cohort of patients with PH (Fig.1). Conclusions STE may aid differential diagnosis of etiology between left heart disease and pulmonary disease in patients with PH. The combination of TDI E/E’ and PALS to calculate LA stiffness offers the most accurate prediction of PH with cardiac etiology.

Utility of left atrial strain in differentiating between cardiac amyloidosis and hypertrophic cardiomyopathy

Abstract Introduction and Objectives Cardiac amyloidosis (AL) is a disease characterized by the abnormal accumulation of anomalous proteins in cardiac tissue, while hypertrophic cardiomyopathy (HCM) is a hereditary cardiac disease characterized by abnormal thickening of the cardiac muscle, associated with tissue fibrosis and cardiac dysfunction in its natural progression. The echocardiogram has emerged as a fundamental tool in the diagnosis and follow-up of these patients, and strain analysis techniques can provide highly useful additional information on cardiac function in these patients, especially in the early stages of the disease. We questioned whether it might be useful in differentiating between these two diseases. Methods This retrospective analysis included adult patients who had undergone echocardiography at our center during the years 2023-2024. A total of 52 patients with a confirmed diagnosis of transthyretin AL confirmed by scintigraphy and/or biopsy, and another group of 51 patients with a confirmed diagnosis of HCM and ICD carriers for being high-risk patients were included. Various left atrial strain values (Reservoir, Conduit, and Pump) were analyzed. Descriptive statistics were calculated for each group and segment, and the Mann-Whitney U test was used to compare the groups. Results Patients with AL showed significantly lower absolute strain values compared to patients with HCM in all three analyzed varieties (Reservoir, Conduit, and Pump) with p&amp;lt;0.01 for all comparisons. The mean strain in the HCM group was 18.57 for reservoir strain, -11.85 for conduit strain, and -6.94 for pump strain; while the mean in the AL group was 9.28, -6.93, and -3.10, respectively. Conclusions Our study found significant differences in left atrial strain values between patients with HCM and patients with transthyretin AL. These findings suggest that left atrial strain analysis could be useful in evaluating cardiac function, follow-up, and differential diagnosis between patients with AL and HCM, especially in the earlier stages of the disease, where it is more challenging to establish a reliable diagnosis. HCM Vs amyloidosis