Suchergebnisse

Comunicació presentada a: Computing in Cardiology Conference (CinC) celebrat del 23 al 26 de setembre de 2018 a Maastricht, Països Baixos. ; Electrocardiographic Imaging (ECGI) can unmask electrical abnormalities that were difficult to detect using the standard 12-lead ECG. However, it is still challenging to interpret the potential arrhythmogenic consequence of electrical patterns found with ECGI. Here, we introduce a computational framework that allows personalized simulations of cardiac electrophysiology (EP) to mimic electrical substrate as detected in an individual, to study the interaction between that substrate and premature ventricular complexes (PVCs). In patient data, electrical substrate identified using ECGI shows regions of pronounced dispersion of local recovery (i.e., recovery gradients). A computational model of ventricular EP was developed and then used to mimic the recovery gradients and PVCs found in patients. We studied a variety of gradients (6-98 ms/cm) and coupling intervals of the extra stimulus (-70 to +260 ms relative to the end of local recovery), which showed that re-entry can only occur when dispersion of recovery is large (≥76 ms/cm), and the extra stimulus occurs just after local recovery ended (~+40 ms). In conclusion, this computational framework allows to identify the specific conditions under which ECGI-detected substrates and PVCs can lead to re-entry in a personalized approach. ; This work is supported by the European Union Horizon 2020 Programme for Research and Innovation, under grant agreement No. 642676 (CardioFunXion).

Cardiac modeling has recently emerged as a promising tool to study pathophysiology mechanisms and to predict treatment outcomes for personalized clinical decision support. Nevertheless, achieving convergence under large deformation and defining a robust meshing for realistic heart geometries remain challenging, especially when maintaining the computational cost reasonable. Smoothed particle hydrodynamics (SPH) appears to be a promising alternative to the finite element method (FEM) since it removes the burden of mesh generation. A point cloud is used where each point (particle) contains all the physical properties that are updated throughout the simulation. SPH was evaluated for solid mechanics applications in the last decade but its capacity to address the challenge of simulating the mechanics of the heart has never been evaluated. In this paper, a total Lagrangian formulation of a corrected SPH was used to solve three solid mechanics problems designed to test important features that a cardiac mechanics solver should have. SPH results, in terms of ventricle displacements and strains, were compared to results obtained with 11 different FEM-based solvers, by using synthetic cardiac data from a benchmark study. In particular, passive dilation and active contraction were simulated in an ellipsoidal left ventricle with the exponential anisotropic constitutive law of Guccione following the direction of fibers. The proposed meshless method is able to reproduce the results of three benchmark problems for cardiac mechanics. Hyperelastic material with fiber orientation and high Poisson ratio allows wall thickening/thinning when large deformation is present. ; The work is supported by the European Union Horizon 2020 research and innovation programme under grant agreement No 642676 (CardioFunXion).

Comunicació presentada a la 9th international conference on Functional Imaging and Modeling of the Heart (FIMH 2017), celebrada els dies 11 a 13 de juny de 2017 a Toronto, Canadà. ; Finite element methods (FEM) are generally used in cardiac 3D-electromechanical modeling. For FEM modeling, a step of a suitable mesh construction is required, which is non-trivial and time-consuming for complex geometries. A meshless method is proposed to avoid meshing. The smoothed particle hydrodynamics (SPH) method was used to solve an electrophysiological model on a left ventricle extracted from medical imaging straightforwardly, without any need of a complex mesh. The proposed method was compared against FEM in the same left-ventricular model. Both FEM and SPH methods provide similar solutions of the models in terms of depolarization times. Main differences were up to 10.9% at the apex. Finally, a pathological application of SPH is shown on the same ventricular geometry with an added scar on the heart wall. ; The work is supported by the European Union Horizon 2020 research and innovation programme under grant agreement No 642676 (CardioFunXion).