Authors: Sara Valvez, Vítor Miguel Santos, L. Gonçalves, A. P. Piedade, A.M. Amaro

The left atrial appendage (LAA) is a major source of thromboembolism, and its mechanical occlusion is a therapeutic option for patients who cannot tolerate anticoagulation. However, its morphological variability complicates device sizing, highlighting the need for biomimetic models that reproduce both geometric and mechanical behavior. This study evaluated the ability of auxetic structures to mimic the mechanical behavior of LAA tissue. Three auxetic geometries (re-entrant bow-tie, missing rib, and missing rib cut) and one rectilinear reference geometry were combined with elastomeric materials with Shore A hardness values of 60A, 70A, and 85A. The re-entrant bow-tie geometry with Shore A 70 provided the closest approximation to the characteristic J-shaped behavior of LAA tissue.

Sara Valvez¹ | Vítor Miguel Santos¹ | L. Gonçalves² | A. P. Piedade¹ | A.M. Amaro¹
1 University of Coimbra, Centre for Mechanical Engineering, Materials and Processes (CEMMPRE, ARISE), Department of
Mechanical Engineering, Portugal
2 University of Coimbra, Clinical and Biomedical Research Institute (iCBR), Faculty of Medicine, Portugal