Prosthetic valve degeneration and stent creep

Stent Creep” seen in Hancock bioprosthesis is due to inward bending of the stent struts [1]. It is not obvious on echocardiographic imaging, but increases the transvalvular gradient as measured by Doppler echocardiography. Stent creep tends to increase with time after implantation [2]. It is due to an ultrastructural deformity polypropylene used in the valve stent [3].

Recently valve-in-valve tanscatheter aortic valve implantation has been used to treat bioprosthetic failure due to stent creep [4].

Mechanical valve malfunction

Mechanical valve malfunction could be due to ball degeneration, ball variance, strut fracture, thrombus or pannus. Pannus is the growth of fibrous tissue into the valve structure resulting in increase of transvalvular gradient.

References

  1. Schoen FJ, Schulman LJ, Cohn LH. Quantitative anatomic analysis of “stent creep” of explanted Hancock standard porcine bioprostheses used for cardiac valve replacement. Am J Cardiol. 1985 Jul 1;56(1):110-4.
  2. Akiyama K, Sawatani O, Imamura E, Endo M, Hashimoto A, Koyanagi H. Clinical study of “stent creep” in porcine bioprosthesis. Nihon Geka Gakkai Zasshi. 1988 May;89(5):747-51.
  3. Valente M, Bortolotti U, Thiene G, Arbustini E, Milano A, Mazzucco A, Gallucci V. Post bending of the polypropylene flexible stent in mitral Hancock bioprostheses. Eur J Cardiothorac Surg. 1987;1(3):134-8.
  4. Attia R, Papalexopoulou N, Hancock J, Young C, Thomas M, Bapat V. Successful treatment of failing biological prosthesis because of “Stent creep” with valve-in-valve transcatheter aortic valve implantation. Catheter Cardiovasc Interv. 2015 Aug;86(2):E119-25.