Abstract: Objective To investigate the protective effect of high-pressure carbon monoxide for preservation of ex vivo rabbit
heart graft in comparison with the conventional HTK cardioplegic solution preservation. Methods Heart grafts isolated from
85 New Zealand rabbits were randomly divided into Naive group (n=5), HTK group (n=40) and CO group (n=40). The grafts
underwent no preservation procedures in Naive group, preserved at 4 ℃ in HTK cardioplegic solution in HTK group, and
preserved at 4 ℃ in a high-pressure tank (PO2: PCO=3200 hPa: 800 hPa) in CO group with Krebs-Henseleit solution perfusion
but without cardioplegic solution. After preservation for 2, 4, 6, 8, 10, 14, 18, and 24 h, 5 grafts from the two preservation
groups were perfused for 30 min with a modified Langendorff apparatus and examined for left ventricular systolic pressure
(LVSP), left ventricular diastolic pressure (LVDP), arrhythmia score (AS), myocardial ultrestructure, and cardiac enzyme
profiles. Results After preservation for 6 to 24 h, the cardiac enzyme profiles and systolic and diastolic functions were
significantly better in CO group than in HTK group, but these differences were not obvious between the two groups after graft
preservation for 2 to 4 h. Significant changes in the myocardial ultrastructures occurred in the isolated hearts after a 24-h
preservation in both CO and HTK groups, but the myocardial damages were milder in CO group. Conclusion Preservation
using high-pressure carbon monoxide can better protect isolated rabbit heart graft than the conventional HTK preservation
approach especially for prolonged graft preservation.