Optimal storage temperature and benefit of hypothermic cardioplegic arrest for long-term preservation of donor hearts: a study in the dog.

Currently, for practical clinical purposes, the preservation of donor hearts is limited to about 4 h. Transplantation must be finished within this period to assure complete functional recovery upon reperfusion. From the clinical setting it is well known that hypothermia results in a better myocardial preservation during ischemia. During ischemia, rapid catabolism of high-energy phosphates (e.g., ATP and creatine phosphate) occurs. The purpose of this study was to investigate the influence of temperature during a 24-h preservation period on the rate of catabolism of ATP and on the rate of accumulation of breakdown products (ADP, AMP, adenosine, inosine, hypoxanthine, and xanthine). For this purpose, hearts were excised and stored for 24 h at 0.5 degrees, 12 degrees, or 18 degrees C. In addition, the effect of initial cardioplegic arrest was compared with simple normothermic excision of the heart followed by 24 h in cold storage. It was found that the higher the storage temperature, the higher the rate of catabolism of high-energy phosphates and, hence, after 24 h, the lower the final ATP level and the higher the level of breakdown products, mainly nucleosides. It was also found that the initial cardioplegic arrest strongly benefits the preservation of high-energy phosphates as a result of the ATP-sparing effect.