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A mechanical model of the heart that is effective, more versatile and more economical – results from industrial PhD program CardiofunXion with Philips

(Original UPF news)

Most models of the heart use cardiac images comprising pixels or dots to extract a realistic geometry of the anatomy of the heart. The models that seek to simulate cardiac motion require the construction of an elaborate cardiac mesh that entails computational difficulties generated from this set of dots from the images.

Cardiovascular diseases are the leading cause of death worldwide. Most experiments associated with the study of these diseases are conducted on experimental animals and/or people, in trials which often incur high costs. Thanks to the breakthroughs in computational resources and numerical methods, it is possible to make computer simulations to reduce these costs. Recently, cardiac modelling has emerged as a promising tool to study the physiological mechanisms involved in heart diseases, predict the effectiveness of treatment, and help in personalized clinical decision-making.

Cardiac modelling has emerged as a promising tool to study the physiological mechanisms involved in heart diseases, predict the effectiveness of treatment, and help in personalized clinical decision-making

 ”Most computer simulations are based on cardiac mesh methods which require the construction of a good quality mesh, which has a high computational cost and hinders its generalization to different heart geometries”, explains Èric Lluch, first author of a study that presents a meshless method to create a mechanical model of the heart. Compared with existing models, this model has proved its worth in heart simulations and that it can be used as a more versatile and more economical alternative.

Èric Lluch is the first author and Bart Bijnens, Jérôme Noailly and Oscar Camara, researchers from the BCN MedTech Research Unit at the Department of Information and Communication Technologies (DTIC) at UPF, with researchers from Medisys Philips Research in Suresnes (France) and INRIA, Université Côte d’Azur, Sophia Antipolis (France), are co-authors.

“This work means the verification of a mechanical model, although shortly we plan to publish a full electromechanical model made from images from magnetic resonance techniques”, explains Oscar Camara, co-author of the article.

https://www.upf.edu/documents/10193/217772317/Fiura9Eric.jpg/b113ed27-1c04-698f-1d47-b820973ce6dc?t=1560252782980Figure 9 of the paper: four steps in time of the simulation of heart contraction until reaching the solution (grey colour). Comparing the last step with the first, we can see a twisting of the red lines which is caused by the effect of the orientation of the fibres in heart contraction.

A meshless method to create a mechanical model of the heart

The new model is based on smoothed particle hydrodynamics (SPH) that appears to be a promising alternative to the finite element method (FEM) because it removes the burden of generating the mesh. SPH uses a cloud of dots where each point (particle) contains all the physical properties that are updated throughout the simulation. Although in the last decade SPH was evaluated for applications in solid mechanics, its ability to tackle the challenge of simulating cardiac mechanics had never been tried before.

This paper presents this new method and its ability to reproduce and simulate problems of cardiac mechanics. “In particular, we simulated passive dilation and active contraction in an ellipsoidal left ventricle with the exponential anisotropic constitutive law of Guccione following the direction of fibres”, explains Lluch. The study shows that the proposed model is able to reproduce effectively the results of the benchmark problems for cardiac mechanics.

Related work:

Èric Lluch, Mathieu De Craene, Bart Bijnens, Maxime Sermesant, Jérôme Noailly, Oscar Camara, Hernán G. Morales (2019), “Breaking the state of the heart: meshless model for cardiac mechanics”, Biomechanics and Modeling in Mechanobiology, 3 of June,  DOI: 10.1007/s10237-019-01175-9