Heart valve bioprosthesis durability: a challenge to the new generation of porcine valves

Eur J Cardiothorac Surg. 1992:6 Suppl 1:S82-90.

Abstract

Long-term experience with first generation porcine valve xenografts enabled identification of the major limitations to their durability: (1) prosthetic-ventricular mismatch due to the high profile of the stent in patients with mitral stenosis and a small left ventricle; (2) high-pressure fixation with loss of natural collagen crimping in the fibrosa, and wash-out of proteoglycans in the spongiosa; (3) xenograft tissue autolysis, due to the long interval between animal slaughter and aortic valve removal fixation; (4) muscle shelf in the right coronary cusp, which created a gradient and could undergo accelerated calcification and/or spontaneous perforation with time; (5) a flexible polypropylene stent, which could creep or even fracture with consequent inward bending of the stent; (6) progressive time-related dystrophic calcification; (7) host fibrous tissue ingrowth. An awareness of these limitations stimulated technical modifications, which frequently brought about distinct improvements: (1) the reduction of the stent profile eliminated the problem of mismatch, but resulted in a higher tendency towards cusp prolapse and earlier commissural tearing; (2) natural collagen waviness, proteoglycans and cusp extensibility were preserved by employing low or even zero pressure during the fixation process; (3) earlier valve fixation enabled preservation of cell integrity; (4) a new orifice for small valves was designed by replacing the right muscular cusp, thus achieving less gradient and avoiding muscle-shelf-related complications; (5) polypropylene was replaced by Delrin as stent material; (6) calcium-retarding agents like T6 and toluidine blue were applied during commercial processing and storage in order to mitigate tissue mineralization.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Bioprosthesis / classification
  • Bioprosthesis / standards*
  • Bioprosthesis / trends
  • Calcinosis / epidemiology
  • Calcinosis / etiology
  • Heart Valve Prosthesis / classification
  • Heart Valve Prosthesis / standards*
  • Heart Valve Prosthesis / trends
  • Humans
  • Prosthesis Design / standards
  • Prosthesis Failure
  • Quality Control
  • Stents / standards
  • Tissue Preservation / methods
  • Tissue Preservation / standards