Chordae tendineae being cut to release the heart's valves for use in a tissue bank. Parts of the heart taken from a donor or heart transplant recipient can be used in the treatment of other patients. Here the chordae tendineae, fibrous tissue attached to valves in the heart, are being cut to aid dissection. Once dissected, the extracted tissue is treated in antibiotic solution before being cooled and stored in the vapour phase of liquid nitrogen, a procedure known as cryopreservation. Small samples are then tested for disease and if the tissue passes, it is stored until it is matched with an appropriate recipient.