How are the homograft valves preserved?
The tissue is soaked in a chemical product known as DMSO. DMSO is the preservation medium. It displaces water from the tissue at the cellular level. Water has to be driven out of the cells, or when it is frozen it will cause ice crystals that will damage the cells (causing cellular rupture). Once the tissue is saturated with DMSO it is placed in liquid nitrogen which is cooled to a temp of 100-130 degrees below zero. This causes the tissue to freeze instantly and minimizes the damage to the tissue. The allograft is then rock hard and has to be handled very carefully. If dropped (and they have been dropped according to the co. rep.) they will shatter into pieces. When the tissue is shipped it is kept frozen and “dry packed”. When it gets to the operating room there is a slow procedure of warming and dilution to get rid of the DMSO and unfreeze. An interesting side note DMSO is a solvent, I’m not sure approved by the FDA for any use other than the above. It is used by Horse vets as an an
