Mechanical Analysis of the Connection Structure of a Double-Layered Valve Stent within an Annuloplasty Ring

Background: In this study, to address the failure of mitral valve repair surgery, a novel valve-in-ring model for an artificial mitral valve annuloplasty ring and a new double-layer mitral valve were established. A suitable number and length of ventricular fixation struts within the annuloplasty ring, as well as the implantation depth, result in variations in stress and strain for the inner and outer stent layers. Methods: The compression and self-expansion model of the stent was established via finite element analysis. The changes in stress and strain were analyzed by setting the length and number of the ventricular fixed struts and implantation depth. Results: When only affected by factors such as blood pressure, the maximum stresses of stent structures with three and six ventricular fixed struts are 476 and 222 MPa, respectively, in the right posterior annular region. At implantation depths of 0, 0.5, 1, and 2 mm, the maximum stresses are located in the left posterior annular region of the outer stent and are 740, 697, 709, and 742 MPa, respectively, and the maximum displacements of the inner stent are all in the right posterior ventricular fixed strut region of the posterior annulus and are 3.71, 3.10, 2.48, and 1.87 mm, respectively. In the three and six ventricular fixed strut stents, when the ventricular fixed strut length is 3, 4, and 5 mm, the maximum stresses are 570, 557, and 621 MPa and 674, 666, 644 MPa, respectively. Conclusions: Appropriately increasing the number of ventricular fixed struts can effectively reduce damage to the stent inside the body, and the damage to the stent is relatively consistent across different implantation depths; however, the right side of the stent's posterior annulus is particularly susceptible to damage. However, if the implantation depth is lower, the impact on the inner stent will be more significant. As the number of ventricular fixed struts increases, the strut length variation has a relatively stable impact on stent damage.