Fluid-electro-mechanical model of the human heart for supercomputers
- Autores: Alfonso Santiago
- Directores de la Tesis: Mariano Vázquez (dir. tes.), Raimon Jané Campos (tut. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2018
- Idioma: español
- Tribunal Calificador de la Tesis: José Félix Rodríguez Matas (presid.), Oscar Camara Rey (secret.), Mark Palmer (voc.)
- Programa de doctorado: Programa de Doctorado en Ingeniería Biomédica por la Universidad Politécnica de Catalunya y la Universidad de Zaragoza
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
The heart is a complex system From the transmembrane cellular activity to the spatial organization in helicoidal fibers, it includes severa! spatial and temporal scales The heart muscle is surrounded by two main tissues that modulate how it deforms: the pericardiurn and the blood. The former constrains the epicardial surface and the latter exerts a force in the endocardium. The main function of this peculiar muscle is to purnp blood to the pulrnonary and systernic circulations In this way, salid dynarnics of the heart is as importan! as the induced fluid dynamics. Until today. only partial heart models has been proposed, None of the published works include electrophysiology, salid mechanics and fluid dynamics solved together in a complete heart model In this work, we propase, develop and test a fluid-electro-mechanical rnodel of the human heart.
To start, the heartbeat phenomenon is disassernbled in the different composing problems. The first building block is the electrical activity of the myocites, that induces the mechanical deformation of the rnyocardiurn. The contraction of the muscle reduces the intracavitary space, that pushes out the contained blood At the sarne time, the inertia, pressure and viscous stresses in this fluid exerts a force on the salid wall In this way, we can understand the heart as a fluid-electro-rnechanical problem.
Ali the models are implemented in Alya, the Barcelona Supercornputing Center simulation software A multi-code approach is used, splitting the problem in a salid and a fluid domain. In the former, electrophysiology coupled with salid mechanics are solved. In the later, fluid dynamics in an arbitrary Lagrangian-Eulerian domain The equations are spatially discretized using the finite elements rnethod and temporally discretized using finite differences . Facilitated by the multi-code approach. a novel high performance quasi-Newton method is developed to deal with the intrinsic issues of fluid-structure interaction problems in biomechanics . Ali the schemes are optimized to run in rnassively parallel computers.
A wide range of experiments are shown to validate, test and tune the numerical model. The different hypothesis proposed -- as the critica! effect of the atrium or the presence of pericardium -- are also proven in these experiments . Finally, a normal heartbeat is simulated and deeply analyzed This healthy computational heart is first diseased with a left bundle branch block. After this, its func_tion is restored simulating a cardiac resy.nchronization therapy . Then, A third grade atrioventricular block is simulated in the l:iealthy heart. In this case, the pathologic rnodel is treated with a minimaliy invasive leadless intracardiac pacemaker. This requires to include the device in the geometrical description of the problem, salve the structural problem with the tissue, and the fluid-structure interaction problem with the blood. As final experiment, we test the parallel performance of the coupled solver .
Finally, a first glance in a coupled fluid-electro-mechanical cardiovascular system is shown. This model is build adding a one dimensional model of the arterial network created by the Laboratório Nacional de Computacion Cientifica in Petropolis. Brasil Despite the artificial geometries used, the outflow curves are comparable with physiological observations.
The model presented in this thesis is a step towards the virtual human. In a near future computational models like the presented in this thesis will change how pathologies are understood and treated, and the way biomedical device are designed
