Simulation patient spécifique de la fermeture percutanée de l’auricule gauche, approche numérique et validation expérimentale

Nathan Collin

The Left Atrial Appendages’s (LAA) percutaneous closure is a mini-invasive surgery preventing thromboembolic complications for patients with atrial fibrillation. This procedure consist in deploying Implantable Medical Device that occlude the LAA. Its success depend on the patient-specific choice in type and in size of the DMI. This thesis, conducted in partnership with Sim&Cure, aims to develop patient-specific computational tools to improve surgical planning for this procedure and the experimental validation of these tools. This work is structured in four steps : (1) a literature review on the clinical context, mechanical modeling of LAA tissues, and standards for numerical computation and validation of medical devices, (2) the development of an experimental test bench based on a silicone structure reproducing the AAG with field measurement techniques (stereocorrelation and OCT), (3) the creation of a finite element numerical model based on shell and beam modeling of bodies to simulate device-heart wall interaction, and (4) a sensitivity analysis to rank the impact of model parameters. The test bench allowed to propose an idealized geometry for the LAA and to propose the hypothesis that the polymer fabric of the chosen DMI does not impact the deformation of its metal structure. The digital model was partially validated for static pressurization of the LAA and calibrated using DMI deployment data. The sensitivity analysis revealed that the bending stiffness of the LAA wall and the rotation of the device around its axis of rotation have an insignificant impact, that the deployment depth and the angle of attack outside the LAA’s plane of symmetry have a moderate impact, while the nonlinearity of the LAA’s tissue material and the angle of attack in the LAA’s plane of symmetry have a significant impact on the results. The DMI-LAA interaction has not been fully validated, and research has not identified a relevant clinical indicator to characterize the LAA in its axial direction. The perspectives for this work include enriching the experimental validation database, integrating physiological variability into LAA geometry, and taking into account the physiological preload of the LAA’s tissue. This research establishes scientific basis for the development of approvable patient-specific simulation tools for LAA percutaneous closure. Contributions include an experimental framework, a calibrated numerical model, and a hierarchy of certain critical parameters. These contributions provide a solid basis for the development of a medical device for surgical planning designed to improve the clinical outcomes of patient-specific LAA closure procedures.