Training Patterns Research Articles

3D strain pattern in additively manufactured AlSi10Mg from digital volume correlation

Although much research has focused on AlSi10Mg processed via laser-based powder bed fusion, the material deformation mechanisms at the microscale are still unclear. To improve the current understanding, 3D measurements of the strain field at the microstructural scale are needed to complement surface-based SEM observations. This work demonstrates that X-ray tomography combined with digital volume correlation can be used to measure the strain in the bulk of AlSi10Mg using the Si-rich particles contained in the heat-treated microstructure as markers. The method allows for measuring strains larger than 0.5 % with a spatial resolution of 35 μm and it can thus be used to study the impact of factors like porosity distribution or crystallographic texture on the material deformation and damage mechanisms.

Early Prediction of Impending Exertional Heat Stroke With Wearable Multimodal Sensing and Anomaly Detection.

We employed wearable multimodal sensing (heart rate and triaxial accelerometry) with machine learning to enable early prediction of impending exertional heat stroke (EHS). US Army Rangers and Combat Engineers (N = 2,102) were instrumented while participating in rigorous 7-mile and 12-mile loaded rucksack timed marches. There were three EHS cases, and data from 478 Rangers were analyzed for model building and controls. The data-driven machine learning approach incorporated estimates of physiological strain (heart rate) and physical stress (estimated metabolic rate) trajectories, followed by reconstruction to obtain compressed representations which then fed into anomaly detection for EHS prediction. Impending EHS was predicted from 33 to 69 min before collapse. These findings demonstrate that low dimensional physiological stress to strain patterns with machine learning anomaly detection enables early prediction of impending EHS which will allow interventions that minimize or avoid pathophysiological sequelae. We describe how our approach can be expanded to other physical activities and enhanced with novel sensors.

3D printable spatial fractal structures undergoing auxetic elasticity

Currently simple and conventional structures are unable to meet increasingly critical and diverse applications, as well as establishment of constitutive relationship of complex structure is becoming a major challenge in materials and mechanics disciplines. To overcome these challenges, fractal structures have attracted much attention due to their abilities to establish constitutive relationships of complex structures. In this study, we design a spatial fractal framework by using high elasticity material and 3D printing method. The constitutive relationships of fractal framework are mathematically modeled. Effects of fractal levels, fractal dimension, and spatial pattern of structures on the mechanical behavior of the fractal framework and assembled spatial fractal structures are studied using both finite element analysis and experimental measurements. The constitutive relationships among stress, strain, fractal dimension, fractal levels, and spatial patterns of structures are proposed and discussed. This paper develops a novel method to establish constitutive relationships of complex structures, and provides theoretical and engineering basis for 3D printable spatial fractal structures undergoing auxetic elasticity.

POLICY DYNAMICS OF VILLAGE APPARATUS CAPACITY BUILDING

The village apparatus is the key to the implementation of good village governance. To ensure the quality of the village apparatus, the government has included a policy to increase the capacity of the village apparatus. By using a qualitative approach, this study aims to see the extent to which capacity building for village officials is running in the field and to see how it impacts efforts to realize good village governance. Based on the findings, several descriptions of policy challenges were obtained, including: the policies have not been implemented in full and well; policies have not been supported by an adequate budget; thematic training methods and patterns are still very limited; not yet optimal standardization and certification of facilitators, and efforts to strengthen the capacity of the village apparatus, which is still limited to the village government apparatus and has not yet been extended to members of other village institutions.

Distributed genotyping and clustering of Neisseria strains reveal continual emergence of epidemic meningococcus over a century

Core genome multilocus sequence typing (cgMLST) is commonly used to classify bacterial strains into different types, for taxonomical and epidemiological applications. However, cgMLST schemes require central databases for the nomenclature of new alleles and sequence types, which must be synchronized worldwide and involve increasingly intensive calculation and storage demands. Here, we describe a distributed cgMLST (dcgMLST) scheme that does not require a central database of allelic sequences and apply it to study evolutionary patterns of epidemic and endemic strains of the genus Neisseria. We classify 69,994 worldwide Neisseria strains into multi-level clusters that assign species, lineages, and local disease outbreaks. We divide Neisseria meningitidis into 168 endemic lineages and three epidemic lineages responsible for at least 9 epidemics in the past century. According to our analyses, the epidemic and endemic lineages experienced very different population dynamics in the past 100 years. Epidemic lineages repetitively emerged from endemic lineages, disseminated worldwide, and apparently disappeared rapidly afterward. We propose a stepwise model for the evolutionary trajectory of epidemic lineages in Neisseria, and expect that the development of similar dcgMLST schemes will facilitate epidemiological studies of other bacterial pathogens.

Transfer‐Free Creation of Hierarchical Wrinkle Patterns for Stretchable and Compliant Strain and Contact Sensing

Higher order hierarchical wrinkle patterns may extend the functionalities and enable new capabilities in the devices created, but current transfer‐based methods are often complex and tedious. This work develops a transfer‐free method to generate hierarchical wrinkle patterns in MXene thin films via controlled deflation of a latex balloon substrate by exploiting its thermal‐elastic properties. This work generates four different wrinkle patterns with varying strain sensitivity: 2D (GF = 0.593), 1D1D (GF = 0.0979), 2D1D (GF = 0.0165), and 2D2D (GF = 0.545). Taking advantage of the small strain response exhibited by the 2D1D electrode, this work fabricates stretchable stain‐insensitive contact sensors where its behavior can be tuned by varying the thickness of the spacer. When the spacer is 0.16 mm thick, the sensor is observed to have a pressure sensitivity of 0.0922, 0.109, and 0.112 kPa−1 at 0%, 25% and 50% stretching states respectively at pressures of <2500 Pa. When the spacer is 0.32 mm thick, the sensor is observed to have a pressure sensitivity of 0.154, 0.185, and 0.233 kPa−1 under 0%, 25% and 50% strain respectively between the pressure range of 2900–5200 Pa.

Research on optimization of electrical parameters of EDM based on a neural network algorithm

An electrical Discharge Machine (EDM) is an effective spark machine that passes the sparks to get the desired shape by performing metal fabrication. In the EDM process, materials are removed between the two electrodes by transferring the workpiece’s high electric voltage and dielectric liquid. The voltage between the two electrodes is gradually increased to break down the dielectrics and remove the materials from the surface. EDM utilizes several parameters to regularize the material removal rate during this process. EDM changes its parameter for every experiment to minimize the Average Tool Wear Rate (ATWR). The existing techniques utilize a neural model to optimize the EDM parameter. However, the traditional approaches fail to perform the fine-tuning process that affects the Material Removal Rate (MRR) and ATWR. Therefore, meta-heuristics optimization techniques are incorporated with the neural model to enhance the EDM parameter optimization process. In this work, the EDM experimental data have been collected and processed by the learning process to create the training pattern. Then, the test data is investigated using the Backpropagation Neural Model (BPM) to propagate the neural parameters. The BPM model is integrated with the Butterfly Optimization Algorithm (BOA) to select the search space’s global parameters. This analysis clearly shows an 8.93% maximum prediction rate, 0.023 minimum prediction rate and 2.83% mean prediction rate while investigating the different testing patterns compared to other methods.

Myocardial mechanics and cardiac biomarkers in adults with severe anorexia nervosa.

Anorexia nervosa (AN) is associated with left ventricular (LV) atrophy and unexplained sudden death. Myocardial mechanics have not been well studied in adults with AN. Whether LV mass or illness duration, markers of AN severity, correlate with abnormal strain imaging is unknown. We performed a prospective study among patients hospitalized with severe AN (n = 29) [body mass index (BMI) < 14.5 kg/m2] and sex/age-matched controls (n = 16) (BMI > 18.5 kg/m2). LV ejection fraction (LVEF) was calculated via modified-biplane method and LV mass was derived using the truncated ellipsoid formula. Apical 2-, 3-, and 4-chamber images were used to generate regional strain mapping and global longitudinal strain (GLS). N-terminal brain natriuretic peptide (NT-proBNP) levels were measured and linear regression was used to determine independent predictors of strain. Mean LVEF did not differ (65% ± 6.0 vs. 62% ± 4.4, p = 0.06), but LV mass was substantially reduced (61.6 ± 16.8 vs. 97.6 ± 19.1 g, p < .0001). GLS was similar (-20.6 ± 3.8 vs. -20.9 ± 2.8, p = 0.82), however, the basal strain was worse (-18.7 ± 4.8 vs. -21.9 ± 4.1, p = 0.03). Lower LV mass was associated with worsening GLS (r = -0.40, p = 0.003), but not among controls (p = 0.89). Median (IQR) NT-proBNP (pg/ml) was higher in patients with AN [141 (59-257) vs. 35.5 (21-56.5) p = 0.0007]. Both increasing NT-proBNP and illness duration were associated with worsening strain patterns in AN (both p = .001). While LVEF and GLS did not differ, regional strain variation was noted among patients with AN. Elevated NT-proBNP may reflect increased wall tension from LV atrophy. Whether strain heterogeneity can identify patients with AN, at risk for sudden death, requires further study.

Speckle-Tracking Analysis of the Right and Left Heart after Peak Exercise in Healthy Subjects with Type 1 Diabetes: An Explorative Analysis of the AppEx Trial.

In eight healthy participants with Type 1 diabetes (T1D) exercise-related dynamic cardiac remodeling was analyzed by performing two-dimensional echocardiography, including deformation analysis of the left-ventricular (LV) global longitudinal strain (LV-GLS), and the deformation pattern of the left atrium (LA) and right ventricle (RV) at rest and post-peak performance on a bicycle. The feasibility echocardiographic speckle-tracking analysis was performed on eight asymptomatic participants with T1D (n = 8, male n = 5, age: 23-65 years). The obtained echocardiographic data were compared for various echocardiographic parameters at rest and post exercise. Across our participating T1D individuals no structural echocardiographic abnormalities of concern could be revealed. All participating T1D subjects showed preserved contractile reserve of the LV and no significant diastolic dysfunction. Significant differences were found for the phasic LA contractile strain pattern at rest and post exercise (p < 0.001), whereby the dynamic RV (p = 0.5839 and p = 0.7419) and LV strain pattern (p = 0.5952) did not reveal significant differences in comparison to resting conditions. This descriptive secondary outcome analysis describes preserved contractile reserve of the LV and elucidates dynamic modification of the phasic LA contractile deformation pattern in asymptomatic T1D individuals after exhaustive exercise on a bicycle.

Relative longitudinal strain apical sparing pattern and low albumin as detrimental factors of cardiovascular outcome after transcatheter aortic valve replacement

Abstract Background Relative apical sparing pattern (RASP) of longitudinal strain (LS), a typical echocardiographic feature of cardiac amyloidosis, is associated with cardiac death or heart failure admission in severe aortic stenosis (AS) patients, and associated with all-cause death among elderly patients with severe AS undergoing transcatheter aortic valve replacement (TAVR). Purpose Present study aimed to explore clinical and echocardiographic determinants of short-term and long-term CV outcome (including CV death and CV hospitalization) in symptomatic severe AS patients after TAVR, and to assess the independent and incremental prognostic value of RASP on CV outcome in TAVR patients. Methods This retrospective study comprised 598 consecutive AS patients underwent TAVR (mean age 81.7±5.7 years, 48.7% male). Pre-operative clinical and echocardiography data, including 2D speckle tracking imaging indexes, were analyzed. Clinical outcomes included CV death and procedure related complications at 30 days, 1 year, and at 2 years after TAVR. Results Relative apical sparing pattern (RASP) of longitudinal strain (LS) was defined as ≥3 LV wall segments with the apical-basal LS ratio &amp;gt;3.0. The prevalence of RASP was 19.2%. Compared with patients without RASP, patients with RASP were associated with higher risk of acute kidney injury (AKI, 10.4% vs. 3.3%, P=0.001) and new-onset left bundle branch block (LBBB) after TAVR (17.4% vs. 6.8%, P&amp;lt;0.001) and higher 2-year CV mortality (22.6% vs. 9.9%, P&amp;lt;0.001, Figure 1) after TAVR. Lower pre-procedural albumin level and RASP were identified as independent determinants of increased 2-year CV mortality (RASP: HR=2.178, P=0.002; albumin&amp;lt;4.0g/dl: HR= 2.548, P&amp;lt;0.001), regardless of TAVR approach and EuroSCORE II. After adjustment, the addition of RASP significantly improved prognostic power of a model including clinical variables and low albumin level for predicting 2-year CV death (χ2 from 28.179 to 40.699, P=0.001, Figure 2). Conclusion RASP is a significant determinant of AKI and new-onset LBBB after TAVR. RASP together with low pre-procedural albumin level serve as the strongest determinants of increased risk of 2-year CV mortality after TAVR.Figure 1Figure 2

Identification of novel risk profiles for ventricular arrythmias in hypertrophic cardiomyopathy through clustering analysis including left ventricular strain data

Abstract Aims The excess mortality in hypertrophic cardiomyopathy (HCM) patients is mainly attributed to the occurrence of ventricular arrythmias (VA) and sudden cardiac death (SCD). The prediction of VA remains challenging and could be improved. The aim of the study was to characterize VA risk profile in HCM patients through clustering analysis combining clinical and conventional imaging parameters with information derived from left ventricular longitudinal strain analysis (LV-LS). Methods A total of 434 HCM patients (65% men, mean age 56 years) were retrospectively included from two referral centers from two different countries and followed longitudinally (mean duration 6 years). Mechanical and temporal parameters were automatically extracted from the LV-LS segmental curves of each patient in addition to conventional clinical and imaging data. A total of 287 features were analyzed using a clustering approach (k-means). The first endpoint for ventricular arrythmias (VA) included suspected SCD, aborted cardiac arrest, appropriate ICD therapy (AIT), sustained ventricular tachycardia (SVT) and non-sustained ventricular tachycardia (NSVT) during follow-up. Results 4 clusters were identified with a higher rhythmic risk for cluster 1 and 4 (VA rates of 26%(28/108), 13%(13/97), 12%(14/120), and 31%(34/109) for cluster 1,2,3 and 4 respectively) (Figure 1). These 4 clusters have been mainly separated based on LV strain parameters with severe and homogeneous decrease of myocardial deformation for cluster 4 (global longitudinal strain (GLS) -11%), a small decrease for cluster 2 and 3 (GLS -17.2 and -16.3%, respectively) and a marked mechanical and temporal dispersion for cluster 1 associated with a moderate decrease of the GLS (-15.3%; p &amp;lt;0.0001 for GLS comparison between clusters) (Figure 2). Patients from cluster 4 had the most severe phenotype (mean LV mass index 123 vs. 112 g/m²; p=0.0003) with marked diastolic dysfunction (left atrial volume index (LAVI) 46.6 vs. 41.5 ml/m² for others clusters; p=0.04) and impaired exercise capacity (% predicted peak work 58.6 vs. 69.5%; p= 0.025). Patient from cluster 2 had the less severe phenotype (mean LV mass index 99.6 vs. 121 g/m²; p=0.0001 and LAVI 37.2 vs. 44.3 ml/m²; p=0.04). Patients from cluster 3 and 1 had a moderate phenotype and were older in cluster 3 (mean age 62.1 vs. 54.1 years; p &amp;lt; 0.0001) and had more obstructive form in cluster 1 (peak gradient LV outflow tract ≥ 30 mmHg for 36 vs. 23% of patients; p=0.046) with a larger left atrium size (LAVI 45.8 vs. 41.7 ml/m²; p=0.0023). Conclusion Using a clustering approach processing LV-LS parameters in HCM patients identified 4 clusters with specific LV-strain patterns and different rhythmic risk level. In the future, the automatic extraction and analysis of LV strain parameters could help to improve the risk stratification for SCD in HCM patients.Figure 1:Survival curvesFigure 2:Different strain patterns

Diagnostic accuracy of apical sparing pattern in transthyretin-derived cardiac amyloidosis assessed by two-dimensional strain echocardiography

Abstract Background Cardiac amyloidosis (CA) is a rapidly progressive disease that portends poor prognosis. Recently, transthyretin-derived CA (ATTR-CA) has attracted attention due to the emergence of specific drugs, and its simple and accurate diagnosis is required. Apical sparing pattern of regional longitudinal strain (LS) distribution has been known as specific echocardiographic finding for CA. However, its diagnostic significance is unclear when limited to ATTR-CA. Aims This study aimed to investigate the diagnostic accuracy of apical sparing pattern to distinguish ATTR-CA from other left ventricular hypertrophic diseases. Methods This was a retrospective study evaluating 32 patients underwent endomyocardial biopsy for differentiation of left ventricular hypertrophy from November 2018 to August 2022. Based on clinical data, patients were classified into 9 patients in ATTR-CA, 14 patients in hypertrophic cardiomyopathy (HCM), and 9 patients in hypertensive heart disease (HHD). In addition to routine echocardiographic findings, left ventricular LS analysis was performed. Relative regional strain ratio (RRSR) as an index of apical sparing pattern was measured as the average of apical LS divided by the sum of the average of mid and basal LS values. Results RRSR in ATTR-CA group was significantly higher than in HCM and HHD groups (0.96 vs. 0.68 vs. 0.72, P=0.004) (Table). In the receiver-operating characteristic analysis of RRSR for differentiating ATTR-CA from HCM and HHD, the optimal cut-off value of RRSR for the diagnosis of ATTR-CA was 0.93 (sensitivity 67%, specificity 96%, area under the curve 0.84) (Figure). Conclusions Apical sparing pattern may have acceptable accuracy in diagnosing ATTR-CA versus other left ventricular hypertrophic diseases, but the relatively low sensitivity may be a clinical limitation.Table:Echocardiographic dataFigure

Transthyretin amyloid cardiomyopathy among patients with hypertrophic cardiomyopathy: clinical, cardiac imaging, and electrocardiographic findings from the TTRACK study

Abstract Background Transthyretin amyloid cardiomyopathy (ATTR-CM) is often misdiagnosed as hypertrophic cardiomyopathy (HCM). Identifying ATTR-CM in patients with HCM is essential because treatment approaches vary, especially with the availability of disease-modifying therapies for ATTR-CM. In this analysis of the TTRACK study, we investigated clinical, cardiac imaging, and electrocardiogram (ECG) features of ATTR-CM that may heighten suspicion of amyloid disease and prompt further screening in patients with HCM. Purpose Explore the clinical, echocardiogram (echo), magnetic resonance imaging (MRI), and ECG findings of patients with HCM screened for ATTR-CM in the TTRACK study. Methods In this global, multicentre, non-interventional epidemiological study, the prevalence of ATTR-CM was assessed in patients ≥50 years of age with HCM of unknown aetiology (left ventricular [LV] maximum wall thickness ≥15 mm [echo]) using 99mTc-DPD/99mTc-PYP/99mTc-HMDP-labeled bone scintigraphy. Nuclear images were graded based on cardiac vs bone radiotracer uptake following the Perugini system. Monoclonal protein testing was performed to exclude light chain amyloidosis. Results Of 766 eligible patients with scintigraphy data, 521 (68.0%) had no cardiac uptake; 37 (4.8%) had low uptake (grade 1); and 208 (27.2%) had moderate/high uptake (grade 2/3). Among patients with moderate/high uptake (cardiac amyloidosis [CA]), 137 (65.9% of patients with CA; 17.9% of the overall cohort) had confirmed ATTR-CM. Comparing NYHA classification of patients with no cardiac uptake vs those with ATTR-CM, 33.8% and 25.0% were asymptomatic (NYHA class I). Marked numerical differences were observed in some echo findings of patients with no cardiac uptake vs ATTR-CM, including mean LV mass index (155.6 vs 177.0 g/m2) and the proportions of patients with preserved apical strain (57.9% vs 74.2%) and concentric hypertrophic pattern (38.8% vs 77.8%) (Table [A]). Although a smaller percentage of patients with ATTR-CM exhibited LV outflow tract (LVOT) obstruction than patients with no cardiac uptake, 12.5% of patients with ATTR-CM had LVOT obstruction (LVOT gradient &amp;gt;30 mmHg). A substantially lower proportion of patients with no cardiac uptake (54.7%) had late gadolinium enhancement on MRI than those with ATTR-CM (84.6%). Notable ECG differences were seen in PR interval (179.4 vs 196.9 ms) and the proportion with poor precordial R wave progression (21.9% vs 47.9%) (Table [B]). Conclusions In the TTRACK study, conducted in the largest cohort of patients with HCM ever screened for ATTR-CM, approximately 18% of patients ≥50 years of age with HCM had findings indicative of ATTR-CM. Noteworthy differences in some clinical, cardiac imaging, and ECG findings were seen between patients with HCM with and without ATTR-CM, but none appeared to be definitive. These findings suggest that broader screening for amyloid disease with scintigraphy should be considered among all patients with HCM.

The added value of abnormal regional myocardial function for risk prediction in arrhythmogenic right ventricular cardiomyopathy

Abstract Background &amp; aims A risk calculator for individualized prediction of first-time sustained ventricular arrhythmia (VA) in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients has recently been developed and validated. This study aimed to investigate whether regional functional abnormalities, measured by echocardiographic deformation imaging, can provide additional prognostic value. Methods &amp; results From two referral centres, 150 consecutive patients with a definite ARVC diagnosis, no prior sustained VA and an echocardiogram suitable for deformation analysis were included (aged 41 ± 17 years, 50% female). During a median follow-up of 6.3 (IQR 3.1-9.8) years, 37 (25%) experienced a first-time sustained VA. All tested left and right ventricular (LV, RV) deformation parameters were univariate predictors for first-time VA. While LV function did not add predictive value in multivariate analysis, two RV deformation parameters did; RV free wall longitudinal strain and regional RV deformation patterns remained independent predictors after adjusting for the calculator-predicted risk (HR 1.07 [1.02-1.11]; p = 0.004 and 4.45 [1.07-18.57]; p = 0.040, respectively) and improved its discriminative value (from C-statistic 0.78 to 0.82 in both. Akaike information criterion change &amp;gt;2). Importantly, all patients who experienced VA within 5 years from the echocardiographic assessment had abnormal regional RV deformation patterns at baseline. Conclusions This study showed that regional functional abnormalities measured by echocardiographic deformation imaging can further refine personalized arrhythmic risk prediction when added to the ARVC risk calculator. The excellent negative predictive value of normal RV deformation could support a watchful waiting strategy regarding ICD implantation in intermediate risk patients.Added value of functional abnormalities

Body Composition of Master Swimmers before and after the COVID-19 Pandemic: A Longitudinal Study.

The long-term effect of physical activity on body composition in Master athletes is rarely presented in the literature. The aim of this study was to identify possible changes in body composition of Master swimmers over a period of 4 years, including during the COVID-19 pandemic. Additionally, we wanted to discover if sarcopenia symptoms would occur in Master athletes during the analyzed period. The body compositions of one hundred and sixty-seven Master swimmers were assessed with the InBody 270 analyzer in 2018. In 2022, the measurements were repeated in forty-six men and fourteen women. The Muscle Mass Index and the Skeletal Muscle Index were calculated to identify sarcopenia-related changes in body composition. We surveyed participants to gather data on their training patterns and SARS-CoV-2 infection history. No significant changes in body composition parameters were noted in Master swimmers during the analysis period (p > 0.05). Sarcopenia risk was not identified in examined athletes, and sarcopenia indicators did not change markedly over the 4-year period (p > 0.05). Participants with a history of SARS-CoV-2 infection did not differ from non-infected subjects in terms of body composition. Training cessation during the COVID-19 pandemic and SARS-CoV-2 infection did not induce long-term changes in body composition of Master swimmers. Life-long participation in swimming activities appears to delay negative changes in body composition, including sarcopenia symptoms.

Dynamical linkages between Arctic Oscillations and winter precipitation patterns over the Indian Region

Winter precipitation over the Indian region is mainly beneficial for the maintenance of the glaciers in the mountainous region and associated atmospheric conditions benefit various sectors, including agriculture, water resources, power generation, and tourism, among others. Hence, understanding the variability and teleconnections of winter precipitation is indispensable. The present study focuses on the understanding of dynamical linkages between the Arctic Oscillations (AO) and winter precipitation variability over the Indian region using reanalysis and observational datasets. The analysis reveals the dipole pattern in the precipitation between the western Himalayas and the central Indian region, which is mainly linked with the positive (negative) phase of the AO. The positive (negative) phase of the AO is mainly associated to the Rossby wave with wavenumber 2 and dominated by the quasi-barotropic Euro-Atlantic and Siberian High (Ural-Siberian high and high over Northwest Pacific) which is accompanied by the wave train pattern across Europe through subtropical north Africa and west Asia. The wave train pattern abets the strengthening (weakening and southward movement) of the middle east jet stream and induces anticyclonic (cyclonic) circulation over the Arabian Sea in a positive (negative) regime of the AO. The precipitation dipole between the western Himalayan region and central India is primarily due to the moisture transport from an outflow of anticyclonic (cyclonic) circulation positioned over the north Arabian Sea which is allied with the positive (negative) phase of the AO and associated atmospheric dynamics.

Abstract 18738: 3D Speckle Tracking Echocardiography in Radiation-Associated Cardiac Disease and Associated Mortality Outcomes

Introduction: The 2D echocardiographic features of radiation-associated cardiac disease (RACD) are well-described including aorto-mitral curtain thickness. However, the 3D speckle tracking echocardiographic strain patterns and their predictive risk for all-cause mortality are not well known in RACD. Methods: We studied 441 patients with RACD (63.7 ± 13.4 y; 62.4% female) seen in our institution. Echocardiographic strain patterns of their initial echocardiograms were reviewed. 3D strain analysis using TOMTEC was performed for left ventricle (LV), right ventricle (RV), and left atrium (LA). Primary outcome was all-cause mortality. We constructed 3 Cox regression models: (1) unadjusted; (2) minimally adjusted for age and sex; (3) adjusted for 42 covariates including CV risk factors, cancer history, cardiac treatments, and cardiac function. Results: During a median 6.8 (95%CI 5.7-7.4) years follow-up, 245 patients died. In the unadjusted model, all LV, RV, and LA strain metrics (except for RV free wall strain) were significantly associated with all-cause death. After comprehensive adjustment for 42 covariates, the strain metrics (except for left atrial contraction strain) remained significantly associated with mortality. The strongest predictor for mortality was reduced LV GLS (HR 0.93, 95%CI 0.89-0.96; p &lt;0.001). Conclusions: Abnormal strain patterns in patients with RACD were associated with increased all-cause mortality independently from other known risk factors. Abnormal strain is a distinct feature of radiation-induced cardiac disease, possibly indicating the mechanism of radiation associated cardiac disease. (JED and TSK are first Co-authors)

Abstract 14705: Diastolic Function is Uniquely Augmented by Direct Mechanical Ventricular Actuation in the Failing Heart

Introduction: Diastolic dysfunction represents a significant pathophysiology in cardiomyopathies and heart failure (HF), yet limited therapies exist for treatment. Direct Mechanical Ventricular Actuation (DMVA) is a non-blood contacting device highly unique in its ability to provide both diastolic and systolic support. The purpose of this study was to further evaluate DMVA’s effect on diastolic function in the failing heart. Methods: Adult canine (63.7 ± 13.4 lb, n=9) underwent repeated cycles of ventricular fibrillation to generate progressive levels of acute HF. DMVA was applied to support HF after defibrillation. Intracardiac echocardiography was used to quantify LV longitudinal strain/strain rates using speckle-tracking algorithms. Strain/strain rate peak magnitudes and composite waveforms were analyzed during baseline (n = 35), DMVA (n = 127), and non-support HF (n = 127). One-way ANOVA with post-hoc Tukey’s HSD was used to assess statistical differences (p&lt;0.05) for all comparisons. Results: LV strain metrics were augmented during DMVA support (strain: 20.0 ± 0.5 %, strain rate: systolic, -1.64 ± 0.03 1/s, diastolic, 1.68 ± 0.04 1/s) versus non-supported HF (strain: 9.9 ± 0.2 %, p&lt;0.001, strain rate: systolic, -0.83 ± 0.02 1/s, p&lt;0.001, diastolic, 0.86 ± 0.02 1/s, p&lt;0.001). All strain metrics were increased during DMVA compared to baseline (strain: 14.2 ± 0.4 %, p&lt;0.001, strain rate: systolic, -1.11 ± 0.03 1/s, p&lt;0.001, diastolic, 1.14 ± 0.04 1/s, p&lt;0.001). Composite strain waveforms aligned by systolic peak revealed an early diastolic boost during DMVA relative to baseline (see figure). Conclusions: Diastolic strain dynamics were significantly improved during DMVA in this model of progressive HF. Direct cardiac compression devices can impair diastolic function, which limits feasibility for circulatory support. This study further validates that DMVA restores near physiologic LV strain patterns during HF and uniquely augments diastolic function.

Left bundle branch pacing better preserves ventricular mechanical synchrony than right ventricular pacing: a two-centre study.

Left bundle branch pacing (LBBP) has been shown to better maintain electrical synchrony compared with right ventricular pacing (RVP), but little is known about its impact on mechanical synchrony. This study investigates whether LBBP better preserves left ventricular (LV) mechanical synchronicity and function compared with RVP. Sixty patients with pacing indication for bradycardia were included: LBBP (n = 31) and RVP (n = 29). Echocardiography was performed before and shortly after pacemaker implantation and at 1-year follow-up. The lateral wall-septal wall (LW-SW) work difference was used as a measure of mechanical dyssynchrony. Septal flash, apical rocking, and septal strain patterns were also assessed. At baseline, LW-SW work difference was small and similar in two groups. SW was markedly decreased, while LW work remained mostly unchanged in RVP, resulting in a larger LW-SW work difference compared with LBBP (1253 ± 687 mmHg·% vs. 439 ± 408 mmHg·%, P < 0.01) at last follow-up. In addition, RVP more often induced septal flash or apical rocking and resulted in more advanced strain patterns compared with LBBP. At 1 year follow-up, LV ejection fraction (EF) and global longitudinal strain (GLS) were more decreased in RVP compared with LBBP (ΔLVEF: -7.4 ± 7.0% vs. 0.3 ± 4.1%; ΔLVGLS: -4.8 ± 4.0% vs. -1.4 ± 2.5%, both P < 0.01). In addition, ΔLW-SW work difference was independently correlated with LV adverse remodelling (r = 0.42, P < 0.01) and LV dysfunction (ΔLVEF: r = -0.61, P < 0.01 and ΔLVGLS: r = -0.38, P = 0.02). LBBP causes less LV mechanical dyssynchrony than RVP as it preserves a more physiologic electrical conduction. As a consequence, LBBP appears to preserve LV function better than RVP.

How Fast Can Minibasins Translate Down a Slope? Observations from 2D Numerical Models

Minibasins are important features in salt-bearing basins and are abundant in salt-detached continental slopes where the salt and the overlying sedimentary cover (including minibasins) undergo seaward translation due to gravity. One question which is relevant for understanding the structural evolution of salt-detached slopes is what controls the translation velocity of the salt layer and of overlying minibasins. The aim of this study is three-fold: 1) to compare minibasin downslope translation velocity with salt translation velocity; 2) to understand what controls minibasin translation velocity and 3) to understand how minibasins translating at different velocities can kinematically interact and modify strain patterns around them. To address these questions, we present a 2D numerical modelling study. In addition to parameters that control salt velocity, we show that minibasin thickness is the main factor controlling minibasin velocity in the numerical models. If the minibasin is far from the base-of-salt, its velocity can be estimated by a 1D analytical solution of salt flowing on a slope. Specifically, thicker minibasins translate slower than thinner minibasins. If the minibasin is close to the base-of-salt, viscous drag slows it further, and the numerical results deviate from the 1D analytical solution. Finally, we assess how several minibasins of differing thicknesses and translation velocities, may diverge or converge as they translate downslope, resulting in varying strain patterns around them. Findings from our numerical modelling provide additional conceptual understanding of structural evolution of salt-detached continental slopes that have significant implications for understanding minibasin behaviour, and interpreting strain patterns around them.