Design and numerical analysis of a prosthetic mitral valve with a lantern-shaped variable diameter stent for TMVR

Transcatheter mitral valve replacement (TMVR) faces challenges of stent migration and left ventricular outflow tract (LVOT) obstruction. Traditional stents fail to meet the demands of systolic high pressure, dynamic saddle-shaped annular contraction, and diastolic LVOT protection, while auxiliary anchoring devices may cause tissue damage. To address these issues, we propose a dual-layer lantern-shaped nitinol stent (L-NiTi) with a pressure-responsive diameter modulation. Using SAPIEN 3 Ultra cylindrical cobalt-chromium (C-CoCr) and cylindrical nitinol (C-NiTi) stents as controls, we constructed a finite element native valve stent prosthesis interaction model under cardiac cycle pressure loading to quantify the performance of the stents. Results showed that the L-NiTi exhibited a maximum strain of 8.9%, a 9.17% ± 3.12% loss in prosthetic leaflet area (compared to a 23% loss in controls), a 34 N increase in systolic migration resistance, and an axial displacement of 1.28 mm (compared to 2.16 and 4.78 mm in C-CoCr and C-NiTi controls, respectively). The improved asymmetric lantern-shaped stent maintained a 32 N increase in migration resistance while increasing the neo-LVOT area from 2.52 to 2.81 cm². The proposed new design of stent for TMVR enhances anchoring without compromising LVOT, demonstrating translational potential for TMVR.