Microbiological analysis of cryopreserved human heart valves after storage: a survey of 3 banks in Spain

Several reports have shown liquid nitrogen containers as not being sterile. Microorganism transmission has been observed in different cells and tissues stored under this condition, but there is no data on contamination of stored human valves. We performed a survey on heart valve banking in Spain. Regarding the questionnaire, we have a complete microbiological analysis of 304 thawed tissues prior to implant. In six cases positive culture results were observed. Patient follow-up did not reveal any adverse effects. Although some other possibilities should be stated, contamination of heart valves during storage in liquid nitrogen should be considered as a risk element in tissue banking. Strategies to asses and prevent microbial transmission from liquid nitrogen to heart valve banking ought to be further developed.