scholarly journals Visualization of Myocardial Strain Pattern Uniqueness with Respect to Activation Time and Contractility: A Computational Study

Data ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 79
Author(s):  
Borut Kirn
Keyword(s):  
Parameter Space ◽  
Measurement Errors ◽  
Computational Study ◽  
Myocardial Strain ◽  
Myocardial Tissue ◽  
Connected Component ◽  
Activation Time ◽  
Mechanical Coupling ◽  
Strain Pattern ◽  
High Uncertainty

Speckle tracking echography is used to measure myocardial strain patterns in order to assess the state of myocardial tissue. Because electro-mechanical coupling in myocardial tissue is complex and nonlinear, and because of the measurement errors the uniqueness of strain patterns is questionable. In this study, the uniqueness of strain patterns was visualized in order to revel characteristics that may improve their interpretation. A computational model of sarcomere mechanics was used to generate a database of 1681 strain patterns, each simulated with a different set of sarcomere parameters: time of activation (TA) and contractility (Con). TA and Con ranged from −100 ms to 100 ms and 2% to 202% in 41 steps respectively, thus forming a two-dimensional 41 × 41 parameter space. Uniqueness of the strain pattern was assessed by using a cohort of similar strain patterns defined by a measurement error. The cohort members were then visualized in the parameter space. Each cohort formed one connected component (or blob) in the parameter space; however, large differences in the shape, size, and eccentricity of the blobs were found for different regions in the parameter space. The blobs were elongated along the TA direction (±50 ms) when contractility was low, and along the Con direction (±50%) when contractility was high. The uniqueness of the strain patterns can be assessed and visualized in the parameter space. The strain patterns in the studied database are not degenerated because a cohort of similar strain patterns forms only one connected blob in the parameter space. However, the elongation of the blobs means that estimations of TA when contractility is low and of Con when contractility is high have high uncertainty.

scholarly journals A Divergence-Based Approach for the Identification of Atrial Fibrillation Focal Drivers From Multipolar Mapping: A Computational Study

2021 ◽  
Vol 12 ◽  
Author(s):  
Michela Masè ◽  
Alessandro Cristoforetti ◽  
Maurizio Del Greco ◽  
Flavia Ravelli
Keyword(s):  
Atrial Fibrillation ◽  
Vector Fields ◽  
Computational Study ◽  
Pulmonary Veins ◽  
Proof Of Concept ◽  
Activation Time ◽  
Mapping Data ◽  
Activation Patterns ◽  
Novel Approach

The expanding role of catheter ablation of atrial fibrillation (AF) has stimulated the development of novel mapping strategies to guide the procedure. We introduce a novel approach to characterize wave propagation and identify AF focal drivers from multipolar mapping data. The method reconstructs continuous activation patterns in the mapping area by a radial basis function (RBF) interpolation of multisite activation time series. Velocity vector fields are analytically determined, and the vector field divergence is used as a marker of focal drivers. The method was validated in a tissue patch cellular automaton model and in an anatomically realistic left atrial (LA) model with Courtemanche–Ramirez–Nattel ionic dynamics. Divergence analysis was effective in identifying focal drivers in a complex simulated AF pattern. Localization was reliable even with consistent reduction (47%) in the number of mapping points and in the presence of activation time misdetections (noise <10% of the cycle length). Proof-of-concept application of the method to human AF mapping data showed that divergence analysis consistently detected focal activation in the pulmonary veins and LA appendage area. These results suggest the potential of divergence analysis in combination with multipolar mapping to identify AF critical sites. Further studies on large clinical datasets may help to assess the clinical feasibility and benefit of divergence analysis for the optimization of ablation treatment.

Spatially varying ductile structures in fold-and-thrust belts: insights from laboratory experiments

2021 ◽  
Author(s):  
Sreetama Roy ◽  
Santanu Bose ◽  
Puspendu Saha
Keyword(s):  
Thin Sheet ◽  
Temporal Variations ◽  
Localized Deformation ◽  
Crustal Layer ◽  
Mechanical Coupling ◽  
Strain Pattern ◽  
Thrust Belts ◽  
Fold And Thrust Belts ◽  
Spatio Temporal ◽  
Gravity Driven Flow

<p>Fold and thrust belts (FTBs), formed by the collision of two continental plates, accommodate tectonic convergence through folding and faulting of crustal rocks. The effects of distributed deformation although ubiquitous in all fold-and-thrust belts, regionally occurring ductile structures are often interpreted as an outcome of localized deformation. Our study presents 3D laboratory-scale models using a viscous thin sheet as crustal layer to investigate the evolution of distributed ductile strain in FTBs. Here, we tested the role of mechanical coupling at the basal decollement (i.e., weak versus strong) on the nature of ductile strain variations within a deforming tectonic wedge. Convergence velocity has been kept constant in all experiments to avoid the influence of rate-dependence on viscous rheology. Our results reveal that the mode of wedge growth with changing basal coupling is crucial for varying strain pattern towards the hinterland. Weak decollement models yield a zone of constriction towards the central part of the hinterland, explaining the occurrence of isolated patches of L-tectonites and cross-folds in FTBs; while strong decollement condition allows the gravity-driven flow to be dominant over horizontal shortening, leading to rotation of earlier structures and formation of orogen-parallel recumbent folds, particularly towards the hinterland. The deformation towards the frontal part of the tectonic wedge, irrespective of coupling strength in both models is similar, forming a characteristic pattern of pervasive, hinterland dipping ductile fabrics. We correlate our findings to infer that spatio-temporal variations in basal coupling are responsible for the development of variably occurring ductile structures in FTBs.</p>

scholarly journals Experimental and Computational Study of Thermal Processes in Red Clays Exposed to High Temperatures

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2211 ◽  
Author(s):  
Václav Kočí ◽  
Lenka Scheinherrová ◽  
Jiří Maděra ◽  
Martin Keppert ◽  
Zbigniew Suchorab ◽  
...  
Keyword(s):  
Functional Properties ◽  
Measurement Errors ◽  
Building Materials ◽  
Energy Savings ◽  
Computational Study ◽  
Specific Treatment ◽  
High Volume ◽  
Thermal Processes ◽  
Energy Demands ◽  
Fired Bricks

Fired bricks represent one of the most popular building materials, of which production is still growing. Since the functional properties of bricks have reached their physical limits, the current development aims at an optimization of production procedures as it goes along with heavy environmental loads. This paper is focused on tailoring the firing procedure to optimize the energy demands. Dealing with five different clays, their heat storage properties are determined using inverse analysis of calorimetric data so that the measurement errors are reduced. Moreover, effective values incorporate the thermal processes that occur during firing. A simplified model of clay samples is then used to calculate the energy demands for reaching an optimal firing scheme. The results show that specific treatment is necessary for particular clays as the energy demands may range between 89 and 173 MJ·m−2, depending on a clay composition. The highest demands were found in the case of clays containing the high volume of calcite and dolomite, of which thermal decomposition is very energy demanding. Using the tailored firing scheme, one can reach energy savings of up to 49% while the functional properties would be preserved due to maintaining the optimal temperature evolution in the brick body.

Myocardial strain pattern progress in patients with Coarctation of the Aorta undergoing aortic stenting

2020 ◽  
Author(s):  
Natalia Freitas de Deus Vale Aragão ◽  
Juliana Nicchio Valentim Borgo ◽  
Carlos Alberto de Jesus ◽  
Tathiane Davoglio ◽  
Anderson da Costa Armstrong ◽  
...  
Keyword(s):  
Myocardial Strain ◽  
Coarctation Of The Aorta ◽  
Strain Pattern ◽  
Aortic Stenting

Myocardial strain pattern in patients with cardiac amyloidosis secondary to multiple myeloma: a cardiac MRI feature tracking study

2016 ◽  
Vol 34 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Sabha Bhatti ◽  
Srikanth Vallurupalli ◽  
Stephanie Ambach ◽  
Adam Magier ◽  
Evan Watts ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Cardiac Mri ◽  
Feature Tracking ◽  
Cardiac Amyloidosis ◽  
Myocardial Strain ◽  
Strain Pattern

Apical sparing strain pattern observed in danon disease: insights from a global registry

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
Q Bui ◽  
G Ma ◽  
M Kraushaar ◽  
V Escobedo ◽  
B Le ◽  
...  
Keyword(s):  
Cardiac Amyloidosis ◽  
Longitudinal Strain ◽  
Global Longitudinal Strain ◽  
Myocardial Strain ◽  
Posterior Wall ◽  
Volume Index ◽  
Danon Disease ◽  
Strain Pattern ◽  
Echocardiographic Parameters ◽  
Echocardiographic Images

Abstract Background Danon Disease (DD) is a rare X-linked autophagic disorder due to mutations in the Lysosomal Associated Membrane Protein 2 (LAMP-2) gene and causes severe cardiac manifestations. Measurement of longitudinal strain (LS) has been shown to provide diagnostic insights into different etiologies of hypertrophic cardiomyopathies compared to conventional echocardiographic parameters. Purpose The aim of this study was to describe the pattern of global and regional LS in DD. Methods A retrospective, international registry, using medical records provided by patients, was formed to describe the natural history of DD. Complete echocardiogram images were available for review and LS was analyzed globally and regionally (basal, mid, apex). Results A total of eighteen DD patients (male 72%, mean age 17.2±10 years) had sufficient quality echocardiographic images for both traditional and myocardial strain evaluation. Notable traditional echocardiographic parameters included a mean EF of 60±11%, LV mass index 200±159 g/m2, intraventricular septal diameter 17.7±10.3 mm, LV posterior wall diameter 16.1±7.7 mm, LA volume index 21.9±13 mL/m2. Global longitudinal strain was reduced with a mean of −12.1±4.9% with an observed regional strain gradient: apex (−16.6±6.6%), mid (−10.9±4.7%) and basal (−9.2±4.5%). Bull's eye plot patterns reflected an apical sparing pattern that was similar to that described in cardiac amyloidosis. Conclusion In this DD cohort, we describe for the first time a strain pattern characterized by reduction in global longitudinal strain with apical sparing, which was originally pathognomonic for cardiac amyloidosis. This strain pattern in conjunction with a paradoxically normal LA volume may discriminate patients with DD from other hypertrophic conditions. Funding Acknowledgement Type of funding source: None

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