Transcatheter Aortic Valve Implantation as Valve in Valve in Degenerated Stentless Bioprothesis—Feasible or Not?

Objectives: Numerous patients received stentless valve prostheses in the past 15 years. Following degeneration of these valves, those patients are in need of replacement. While transcatheter aortic valve implantation (TAVI) as valve in valve (ViV) is performed on a daily basis in stented bioprostheses, it is yet controversially discussed in stentless prostheses, especially in cases without significant calcification. At present, the safety of fixation of the transcatheter valve (TCV) as well as the risk of rupture during implantation in the stentless prosthesis is unclear. Therefore, we present the results of an in vitro study addressing these problems.

Methods: Degenerated stentless biological valves (SV) of different sizes (23 and 25 mm Köhler Root Elan) were investigated before and after implantation of TCV (Edwards Sapien 23 mm or Medtronic Evolut 23 mm). We tested the valves and ViV combinations in a HKP 2.0 pulse duplicator simulating 70 bpm and 70 mL stroke volume (cardiac output 4.9 L/min). Geometrical fixation, mean transvalvular gradient (MTVG), closing time, and volume, leakage volume, of nine separate measurements were assessed and compared between valve combinations (SV-ME: ViV with Medtronic Evolut, SV-ES: ViV with Edwards Sapien). Function of all valves was visualized by means of a high-speed camera at 1,000 frames/s.

Results: The fixation of both TCV implantation types was safe in all combinations and no significant movement of the TCV after implantation was seen. No rupture of the stentless valve was observed following implantation of Edwards Sapien under moderate implantation pressure (max. 15 atm). MTVG were lower after TCV implantation. SVME exhibited Tte lowest gradients (SV: 10.2 ± 0.4 mm Hg, SVME: 8.5 ± 0.3 mm Hg, SVEP: 9.9 ± 0.3 mm Hg). Leakage volume remained constant.

Conclusion: We hypothesize that TAVI as ViV is a valid option in cases of stentless bioprothesis. Using the Edwards Sapien valve, a moderate pressure under implantation prevented a rupture of the stentless valve and provided a sufficient fixation of the TCV. Among the valves compared, the Medtronic Evolut valve showed the best hemodynamic performance as ViV.

No conflict of interest has been declared by the author(s).