The effects of -80 °C short-term storage on the mechanical response of tricuspid valve leaflets

Abstract

Mechanical testing of soft tissues would ideally rely on using fresh specimens. In the event that fresh tissues are not readily available, alternative measures, such as storing fresh specimens at -80 °C, could be considered. Previous studies have shown that changes in the mechanical properties of the tissues due to freezing could be tissue-dependent. Prior to our study, however, such information was not available for the tricuspid valve leaflets. As such, for the first time, we examined whether fresh porcine specimens tested in a biaxial tensile machine would offer comparable results after being frozen at -80 °C. The stress-strain response of the tricuspid valve leaflets displayed no major deviation of the post-frozen leaflets as compared to fresh leaflets. We further compared the radial and circumferential strains as an indicator of deformation at similar stress states in fresh and thawed tissues, and we did not find any significant differences. Ice formation within the extra cellular matrix may modify the collagen fiber configuration, resulting in a slight change in the mechanical response. Nevertheless, our results indicated such a small deviation was negligible, thus enabling the possibility of using frozen porcine tricuspid valve specimens for future research.

Keywords: Biaxial mechanical testing; Freezing; Heart valve.