Intraoperative Bioprosthetic Valve Dysfunction Causing Severe Mitral Regurgitation.

Structural degeneration of bioprosthetic valves usually occurs gradually over time. Failure of a bioprosthetic valve immediately after implantation is extremely rare. Possible causes include obstruction of valve leaflets from preserved subvalvular tissue during chordal-sparing mitral valve replacement (MVR) or strut entrapment by suture loops. We report 2 cases of acute bioprosthetic mitral valve (MV) dysfunction involving newly implanted Perimount Theon (Edwards Lifesciences, Irvine, CA) bioprostheses, causing severe transvalvular mitral regurgitation (MR). Rapid diagnosis was achieved with the use of intraoperative transesophageal echocardiography (TEE). Operative assessment and examination of the explanted valves could not determine a definite cause of failure in either case.