Le Dr Lenoir est chirurgien en cardiologie pédiatrique et congénitale - Hôpital de la Timone
2 ème thèse soutenue au M2P2 "Modélisation et simulation numérique des mécanismes d'interaction fluide-structure dans la valve aortique : vers un modèle biomécanique intégré de la valve aortique"
Publications scientifiques au M2P2
2024
Tom Fringand, Loic Mace, Isabelle Cheylan, Marien Lenoir, Julien Favier. Analysis of Fluid–Structure Interaction Mechanisms for a Native Aortic Valve, Patient-Specific Ozaki Procedure, and a Bioprosthetic Valve. Annals of Biomedical Engineering, 2024, 52 (11), pp.3021-3036. ⟨10.1007/s10439-024-03566-1⟩. ⟨hal-04928780⟩ Plus de détails...
The Ozaki procedure is a surgical technique which avoids to implant foreign aortic valve prostheses in human heart, using the patient’s own pericardium. Although this approach has well-identified benefits, it is still a topic of debate in the cardiac surgical community, which prevents its larger use to treat valve pathologies. This is linked to the actual lack of knowledge regarding the dynamics of tissue deformations and surrounding blood flow for this autograft pericardial valve. So far, there is no numerical study examining the coupling between the blood flow characteristics and the Ozaki leaflets dynamics. To fill this gap, we propose here a comprehensive comparison of various performance criteria between a healthy native valve, its pericardium-based counterpart, and a bioprosthetic solution, this is done using a three-dimensional fluid–structure interaction solver. Our findings reveal similar physiological dynamics between the valves but with the emergence of fluttering for the Ozaki leaflets and higher velocity and wall shear stress for the bioprosthetic heart valve.
Tom Fringand, Loic Mace, Isabelle Cheylan, Marien Lenoir, Julien Favier. Analysis of Fluid–Structure Interaction Mechanisms for a Native Aortic Valve, Patient-Specific Ozaki Procedure, and a Bioprosthetic Valve. Annals of Biomedical Engineering, 2024, 52 (11), pp.3021-3036. ⟨10.1007/s10439-024-03566-1⟩. ⟨hal-04928780⟩
Loïc Georges Macé, Tom Fringand, Isabelle Cheylan, Laurent Sabatier, Laurent Meille, et al.. Three-dimensional modelling of aortic leaflet coaptation and load-bearing surfaces: in silico design of aortic valve neocuspidizations. Interdisciplinary Cardiovascular and Thoracic Surgery, 2024, 39 (1), ⟨10.1093/icvts/ivae108⟩. ⟨hal-04971088⟩ Plus de détails...
Three-dimensional (3D) modelling of aortic leaflets remains difficult due to insufficient resolution of medical imaging. We aimed to model the coaptation and load-bearing surfaces of the aortic leaflets and adapt this workflow to aid in the design of aortic valve neocuspidizations. METHODS Geometric morphometrics, using landmarks and semilandmarks, was applied to the geometric determinants of the aortic leaflets from computed tomography, followed by an isogeometric analysis using Non-Uniform Rational Basis Splines (NURBS). Ten aortic valve models were generated, measuring determinants of leaflet geometry defined as 3D NURBS curves, and leaflet coaptation and load-bearing surfaces were defined as 3D NURBS surfaces. Neocuspidizations were obtained by either shifting the upper central coaptation landmark towards the sinotubular junction or using parametric neo-landmarks placed on a centreline drawn between the centroid of the aortic root base and centroid of a circle circumscribing the 3 upper commissural landmarks. RESULTS The ratio of the leaflet free margin length to the geometric height was 1.83, whereas the ratio of the commissural coaptation height to the central coaptation height was 1.93. The median coaptation surface was 137 mm2 (IQR 58) and the median load-bearing surface was 203 mm2 (60) per leaflet. Neocuspidization multiplied the central coaptation height by 3.7 and the coaptation surfaces by 1.97 and 1.92 using the native coaptation axis and centroid coaptation axis, respectively. CONCLUSIONS Geometric morphometrics reliably defined the coaptation and load-bearing surfaces of aortic leaflets, enabling an experimental 3D design for the in silico neocuspidization of aortic valves.
Loïc Georges Macé, Tom Fringand, Isabelle Cheylan, Laurent Sabatier, Laurent Meille, et al.. Three-dimensional modelling of aortic leaflet coaptation and load-bearing surfaces: in silico design of aortic valve neocuspidizations. Interdisciplinary Cardiovascular and Thoracic Surgery, 2024, 39 (1), ⟨10.1093/icvts/ivae108⟩. ⟨hal-04971088⟩
Journal: Interdisciplinary Cardiovascular and Thoracic Surgery
Tom Fringand, Isabelle Cheylan, Marien Lenoir, Loic Mace, Julien Favier. A stable and explicit fluid–structure interaction solver based on lattice-Boltzmann and immersed boundary methods. Computer Methods in Applied Mechanics and Engineering, 2024, 421, pp.116777. ⟨10.1016/j.cma.2024.116777⟩. ⟨hal-04971126⟩ Plus de détails...
Fluid-structure interaction (FSI) occurs in a wide range of contexts, from aeronautics to biological systems. To numerically address this challenging type of problem, various methods have been proposed, particularly using implicit coupling when the fluid and the solid have the same density, i.e., the density ratio is equal to 1. Aiming for a computationally efficient approach capable of handling strongly coupled dynamics and/or realistic conditions, we present an alternative to the implicit formulation by employing a fully explicit algorithm. The Lattice Boltzmann Method (LBM) is used for the fluid, with the finite element method (FEM) utilized for the structure. The Immersed Boundary Method (IBM) is applied to simulate moving and deforming boundaries immersed in fluid flows. The novelty of this work lies in the combination of Laplacian smoothing at the fluid/solid interface, an improved collision model for the LBM, and a reduction of non-physical frequencies on the structure mesh. The use of these adaptations results in a solver with remarkable stability properties, a primary concern when dealing with explicit coupling. We validate the numerical framework on several challenging test cases of increasing complexity, including 2D and 3D configurations, density ratio of 1, and turbulent conditions.
Tom Fringand, Isabelle Cheylan, Marien Lenoir, Loic Mace, Julien Favier. A stable and explicit fluid–structure interaction solver based on lattice-Boltzmann and immersed boundary methods. Computer Methods in Applied Mechanics and Engineering, 2024, 421, pp.116777. ⟨10.1016/j.cma.2024.116777⟩. ⟨hal-04971126⟩
Journal: Computer Methods in Applied Mechanics and Engineering
