Numerical analysis of the radial force produced by the Medtronic-CoreValve and Edwards-SAPIEN after transcatheter aortic valve implantation (TAVI)

A better understanding of the mechanisms producing the radial force in transcatheter heart valves is essential in order to reduce the reported cases of migration and atrio-ventricular block and improve the effectiveness of the treatment. This paper presents a numerical study of the different mechanisms responsible for the radial force exerted on the aortic annulus by self-expanding and balloon-expandable prostheses. The behavior of the Medtronic CoreValve (self-expanding) and the Edwards SAPIEN (balloon-expandable) devices, both of size 26, has been simulated and compared. The results indicate that, for both prostheses, the radial force may vary considerably within the recommended functional range for the valve implantation and is substantially higher at the smallest annular sizes. In particular, in the case of the self-expanding valve the radial force is essentially dependent on the diameter of the left ventricular outflow tract, while for the balloon-expandable valve the radial force produced is influenced by both the geometry and stiffness of the host tissue. The outcomes of this study provide a better insight into the phenomenon and useful information that could support the development of improved solutions.