OBJECTIVETo 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.

METHODSHeart 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 degrees celsius; in HTK cardioplegic solution in HTK group, and preserved at 4 degrees celsius; 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.

RESULTSAfter 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.

CONCLUSIONPreservation using high-pressure carbon monoxide can better protect isolated rabbit heart graft than the conventional HTK preservation approach especially for prolonged graft preservation.