New, Expandable Mitral Annuloplasty Ring Designed to Prevent Central or Paravalvular Leak and Provide Better THV-oversizing Capacities

Objectives: Trans-catheter Valve-in-Ring (VIR) strategies have been developed to treat recurrent MR after failing surgical annuloplasty in selected, high-risk patients. However, this new technique raised considerable problems due to the different geometry and rigidity of the devices (oval, sometimes rigid ring, but round THV), causing suboptimal THV-expansion with consecutive paravalvular or central leakage. This generated the need for a new expandable ring.

Methods: A rigid and saddle-shaped annuloplasty ring (Profile 3D^®, Medtronic Inc., Minneapolis, Minnesota, United States) was interrupted at four locations. The four segments then were re-connected with small tension springs, rearranged to the original shape and covered with a new sewing cuff. The length of the annuloplasty ring construct, including the four ring segments and the completely extended tension springs, was defined by the perimeter of an appropriate THV. This new annuloplasty ring was implanted in the mitral position of an isolated cadaver pig heart. Then, we deployed a Sapien XT^TM (Edwards Lifesciences) THV of greater perimeter within the new ring, expanded it to its maximum extent and investigated the geometrical changes.

Results: Fluoroscopy confirmed correct 3-dimensional, oval, saddle-shape before dilatation. After THV implantation, the four ring segments spread apart and the tension springs were stretched to their maximum extent. As result, the new annuloplasty ring was extended and changed its configuration from “oval” to perfectly “round” shape. The extended new ring construct securely anchored the THV, leaving no paravalvular gaps that potentially could cause insufficiency.

Conclusion: We developed an expandable annuloplasty ring that is perfectly concerted to THV implantation. The proof of concept revealed no paravalvular leaks and great oversizing capacities and might therefore impact future ring design. Further in vivo studies have to evaluate device safety in terms of LVOT-obstruction and durability before it can be introduced in clinical practice. Furthermore, this concept could be introduced in surgical valve bioprosthesis to enable later THV-implantation without the need of downsizing.