Study of cardiovascular function using a coupled left ventricle and systemic circulation model

Abstract

To gain insight into cardio-arterial interactions, a coupled left ventricle-systemic artery (LV–SA) model is developed that incorporates a three-dimensional finite-strain left ventricle (LV), and a physiologically-based one-dimensional model for the systemic arteries (SA). The coupling of the LV model and the SA model is achieved by matching the pressure and the flow rate at the aortic root, i.e. the SA model feeds back the pressure as a boundary condition to the LV model, and the aortic flow rate from the LV model is used as the input for the SA model. The governing equations of the coupled system are solved using a combined immersed-boundary finite-element (IB/FE) method and a Lax–Wendroff scheme. A baseline case using physiological measurements of healthy subjects, and four exemplar cases based on different physiological and pathological scenarios are studied using the LV–SA model. The results of the baseline case agree well with published experimental data. The four exemplar cases predict varied pathological responses of the cardiovascular system, which are also supported by clinical observations. The new model can be used to gain insight into cardio-arterial interactions across a range of clinical applications.

Modelling mitral valvular dynamics–current trend and future directions

“…Thus, an accurately modelled myocardial relaxation process is needed along with pressure boundary conditions in the left atrium. In systole, systemic circulation contributes to the physiologically pressure/flow rate boundary conditions, and this may be modelled using either a simplified Windkessel model or 1‐dimensional structure tree model . Because the flow across AV is driven by the LV contraction, a pressure boundary condition in the AV plane will be easier to implement, and the simulated AV flow rate can be used to validate the model with measured flow rates.…”

“…In systole, systemic circulation contributes to the physiologically pressure/flow rate boundary conditions, and this may be modelled using either a simplified Windkessel model or 1-dimensional structure tree model. 170 Because the flow across AV is driven by the LV contraction, a pressure boundary condition in the AV plane will be easier to implement, and the simulated AV flow rate can be used to validate the model with measured flow rates. Other boundary conditions may also be needed to account for ventricular structure dynamics, such as the motion of the LV basal plane, constrains of the pericardium.…”

Fully coupled fluid‐electro‐mechanical model of the human heart for supercomputers

“…The strongly coupled technique, also called bidirectional or implicit is physically and numerically more accurate due to the enforced energy conservation. As there is no electric depolarization, FSI models of the heart are focused on diastole, [52][53][54][55] or use externally imposed stresses, displacements, or calcium fields [56][57][58][59] to produce systole. In a few exceptional cases, the fluid dynamics outflow is connected with a 1D model of the vessels.…”

“…As there is no electric depolarization, FSI models of the heart are focused on diastole, or use externally imposed stresses, displacements, or calcium fields to produce systole. In a few exceptional cases, the fluid dynamics outflow is connected with a 1D model of the vessels . Fluid‐structure interaction (FSI) models that exclude electrophysiology, also find a large application field, but mainly related with diastolic filling pathologies and devices …”

Advances in computational modelling for personalised medicine after myocardial infarction

“…The ratio between early mitral inflow velocity and mitral annular early diastolic velocity has been used to estimate the ventricular filling pressure, but this can be unreliable in certain situations 29. Systolic ventricular pressure may be inferred from non-invasive cuff-measured blood pressure or by measuring flow in large arteries through coupling circulation models 30. Non-invasively measuring the absolute blood pressure is challenging, though pressure gradients can be estimated from flow measurements.…”