Hemodynamic Assessment of the Pathological Left Ventricle Function under Rest and Exercise Conditions

Abstract

Purpose: The analysis of pathological human left ventricular hemodynamics using high-resolved image-based blood flow simulations shows a major potential for examining mitral valve insufficiency (MI) under exercise conditions. Since capturing and simulating the patient-specific movement of the left ventricle (LV) during rest and exercise is challenging, this study aims to propose a workflow to analyze the hemodynamics within the pathologically moving LV. Methods: Patient-specific ultrasound (US) data of ten patients with MI in different stages were captured with three-dimensional real-time echocardiography. US measurements were performed while patients were resting and while doing handgrip exercise (2–4 min work). Patient-specific hemodynamic simulations were carried out based on the captured ventricular wall movement. Velocity and kinetic energy were analyzed for rest and exercise and for the different MI stages. Results: The results reveal a dependency of the kinetic energy over time in the ventricular volume curves. Concerning the comparison between rest and exercise, the left ventricular function reveals lower systolic kinetic energy under exercise (kinetic energy normalized by EDV; mean ± standard deviation: rest = 0.16 ± 0.14; exercise = 0.06 ± 0.05; p-value = 0.04). Comparing patients with non-limiting (MI I) and mild/moderate (MI II/III) MI, lower velocities (mean ± standard deviation: non-limiting = 0.10 ± 0.03; mild/moderate = 0.06 ± 0.02; p-value = 0.01) and lower diastolic kinetic energy (kinetic energy normalized by EDV; mean ± standard deviation: non-limiting = 0.45 ± 0.30; mild/moderate = 0.20 ± 0.19; p-value = 0.03) were found for the latter. Conclusion: With the proposed workflow, the hemodynamics within LVs with MI can be analyzed under rest and exercise. The results reveal the importance of the patient-specific wall movement when analyzing intraventricular hemodynamics. These findings can be further used within patient-specific simulations, based on varying the imaging and segmentation methods.

Inter‐model and inter‐modality analysis of left ventricular hemodynamics: Comparative study of two CFD approaches based on echocardiography and magnetic resonance imaging

“…The first approach to numerically assess the hemodynamics within the moving domain was MM based on Grünwald et al [18] and Korte et al [28]. The 3D incompressible Navier-Stokes-Equations were solved in ANSYS Fluent (v.2021R2, ANSYS Inc.) and the method was implemented by using user-defined c-functions within the solver.…”

“…At the inlet (pulmonary veins) and outlet (ascending AO) pressure curves of a volunteer, assessed with the CircAdapt tool (CircAdapt, NL) were applied. For further information on setup, mesh and user defined movement, see [18,28].…”

“…This results in 90$$$ \cdotp $$$14 = 1260 surfaces, which prescribe the wall movement and were loaded into the setup with each time step. This resulted in a time step size of 0.6 ms (for further information, see [18] and [28]). At the inlet (pulmonary veins) and outlet (ascending AO) pressure curves of a volunteer, assessed with the CircAdapt tool (CircAdapt, NL) were applied.…”

Verification Study of In Silico Computed Intracardiac Blood Flow With 4D Flow MRI

“…Current research in the field addresses the left ventricle (LV), left atrium (LA), or aorta (AO), structures where cardiovascular diseases often originate or manifest. Subject of investigation are, e.g., intraventricular forces and their impact on remodeling processes [1], energetic efficiency of intraventricular flow [2]- [4], or cyclic washout and blood mixing processes in the context of thrombus formation [5]- [7]. Furthermore, virtual anatomical manipulations allow prior estimation of post-operative outcomes [8]- [10], offering the potential to provide advice where clinical standard procedures are absent.…”