Simulations of left atrial appendage inversion procedure: Patient-specific models with different appendage geometries

Atrial fibrillation (AF) increases the risk of thromboembolic events due to clot formation in the left atrial appendage (LAA). Traditional methods to mitigate AF-related risk involve surgical or percutaneous exclusion of the LAA. Recently, left atrial appendage inversion (LAAI) has been proposed as a device-free, minimally invasive alternative for treating AF. This study uses computational modeling to understand the biomechanical implications of LAAI on four distinct LAA phenotypes: Chicken wing, cactus, windsock, and cauliflower. Structural inversion by finite-element analysis revealed significant changes in stress distribution, with the inverted apex experiencing positive stress surrounded by compressive stress fields peaking at nearly -4 MPa. The use of a stress-growth law predicted tissue resorption in the inverted apex, aligning with clinical and animal studies. Flow velocity and vorticity post-LAAI were estimated using one-way fluid-solid interaction (FSI) modeling. The cactus and cauliflower morphologies showed vorticity maxima of 3.9 1/s and 4.9 1/s, with most vorticity values concentrated around the Q1 quartile. Conversely, the windsock phenotype exhibited lower vorticity risks, indicating a reduced likelihood of thrombogenic events. These findings suggest that patient-specific simulations may improve the development and application of LAAI therapy to optimize clinical outcomes in patients with AF.