Periodic Reporting for period 1 - HI-SiMed (Hemodynamics in an Infarcted heart:from multi-physics Simulations to Medical analysis)
Okres sprawozdawczy: 2019-09-01 do 2021-08-31
The computational framework is seen to provide realistic cardiovascular simulations both in terms of muscular activation, intraventricular hemodynamics and wall shear stresses. In particular, we have shown the propagation of the transmembrane potential over the myocardium triggered by a localized electrical input in the Bachmann and His bundles. The consequent action potential and heart chambers depolarization yields an active muscular tension and tissue contraction that is oriented according to the local direction of the muscular fibers. Hence, the model reproduces also the vigorous three–dimensional twist of the left ventricle from the apex to the valvular plane observed in-vivo. This electro-mechanical activity of the LH chambers originates a complex hemodynamics and valve dynamics, which is in qualitative and quantitative agreement with in-vivo and ex-vivo measurements. The mitral valve connecting the left atrium and ventricle, opens during diastole and closes when the ventricle contracts, owing to the external hydrodynamics loads exerted on its leaflets. At the same time the mitral valve prevents an undesired back-flow of oxygenated blood during systole, the aortic valve opens and blood is propelled in the thoracic aorta. Furthermore, the numerics well reproduces the Wiggers diagram of a healthy human adult reported in medical atlas. This diagram shows the time variation over a heart beat of the pressure in the left ventricle, atrium and thoracic aorta, with the typical pressure variation of 0–120 mmHg in the ventricle. During a heart beat, the ventricular volume diminishes from the maximum (tele-diastolic) volume, which is given as input through the ventricle geometry, to its minimum (tele-systolic) value, which is not imposed and computed as part of the solution. This volume variation of the ventricle corresponds to an ejection fraction of about 60% and a cardiac output of 5.06 l/min, which are typical physiological values for the heart of a healthy adult.
For the first time the hemodynamics of the whole left heart is described in all its details by the state-of-the-art direct numerical simulation of the Navier-Stokes equations and could be used to improve prognoses for cardiovascular diseases. Furthermore, the computational model is predictive because the kinematic of the active heart chambers and valve leaflets are not imposed but come as a result of the full electro-fluid-structure coupling. The intrinsic interdisciplinarity of the project and the two-way transfer of knowledge from medicine to fluid dynamics, in order to simulate heart conditions at best, and from fluid dynamics to medicine, with the aim of improving patient treatments, naturally widens the impact of the research.