New expandable mitral annuloplasty ring facilitates transcatheter mitral valve implantation: proof of concept

AIMS: Transcatheter mitral valve-in-ring (TMVIR) implantation with transcatheter heart valve (THV) prostheses can be performed in patients with recurrent mitral regurgitation (MR) following annuloplasty. However, an oval configuration and sometimes the rigidity of surgical rings can often lead to suboptimal THV expansion, resulting in considerable paravalvular or central leakage. Therefore, our aim was to develop an annuloplasty ring that fully adjusts to THV implantation. METHODS AND RESULTS: A three-dimensional annuloplasty ring was separated into four pieces at defined locations, the sections were reconnected with heat-shrinkable tubing and rearranged into the original shape. A non-tear stainless steel circular cord of defined length was inserted into the ring's sewing cuff to serve as a limiting structure for THV expansion. We implanted this ring in the mitral position into an isolated pig heart, deployed a THV into the ring, and investigated its function. Fluoroscopy showed that, upon THV deployment, the four breaking points of the ring separated as expected, and the ring expanded in a circular fashion to full expansion of the limiting cord. It securely anchored the THV to the ring, leaving no paravalvular gaps. CONCLUSIONS: We developed an expandable mitral ring to which the THV attached without leakage. This may impact on the future design of annuloplasty rings. Further studies should evaluate the safety of increasing the perimeter of a mitral ring and its durability.