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Transcatheter aortic valve (TAV) devices have evolved from first generation Sapien (open leaflets) to second generation Sapien XT (semi-closed leaflets) to current generation Sapien 3 (redesigned stent and sealing skirt). Durability remains a concern as TAVR expands to low-risk younger patients. High leaflet stresses portend poor durability. Our objective was to compare the stress on leaflets and stents across TAV generations.
Edwards Sapien, Sapien XT, and Sapien 3 TAVs (26mm) underwent micro-computed tomography scanning. The precise geometries of stent, leaflets, Dacron, and suture connections were reconstructed based on radiologic images. Finite element simulations were performed using ABAQUS software.
For TAV leaflets, maximum principal stresses on Sapien, Sapien XT and Sapien 3 were 1.31MPa, 1.45MPa and 2.17MPa, respectively at diastolic pressure (figure 1); while minimum principal stresses were -0.45MPa, -0.21MPa, and -0.24MPa respectively. For TAV stents, peak first principal stresses were 188.9MPa, 50.3MPa and 16.3MPa for Sapien, Sapien XT, and Sapien 3, respectively at diastolic pressure.
Our study demonstrated that maximum leaflet stresses appeared in similar locations at the commissural tips across generations. Maximum stress on the leaflets increased while maximum stress on stent decreased with successive TAV generations. Our results suggest that the newer generation of TAV had increased stresses on leaflets which may impact long-term durability. Comparison with similarly sized surgical bioprostheses may lead to further insight into relative TAV durability.
STRUCTURAL: Cardiac Surgery