Cold storage of the heart with University of Wisconsin solution and 2,3-butanedione monoxime: Langendorff vs isolated working rabbit heart model.

Currently, for clinical heart preservation with University of Wisconsin (UW) solution the ischemic time is limited to 8 h. The reliable preservation of the heart for 24 h or more would have a dramatic impact on the existing practice of cardiac transplantation. We showed previously [J. Thorac. Cardiovasc. Surg. 107; 764-775 (1994)] that experimentally preservation could be extended to 24-30 h by preventing ischemic contracture of the heart with 2, 3-butanedione monoxime (BDM) in the UW solution (UWBDM). This resulted in nearly 100% return of function as tested in the isolated crystalloid-reperfused rabbit heart in the nonworking Langendorff preparation. We have confirmed these results and now have measured the function of hearts stored in UWBDM for 2, 4, 12, and 24 h using the isolated working rabbit heart model. Preservation in UWBDM solution resulted in a biphasic decrease of cardiac output. In the hearts preserved for 2-12 h the decrease of function averaged 20-35% upon reperfusion, and the differences at 2, 4, or 12 h were not significant (analysis of variance p > 0.05). A more pronounced decrease of 64% was obtained after 24 h of cold storage. Hearts preserved for 24 h without BDM were practically nonfunctional. The release of enzymes (creatine kinase and lactate dehydrogenase) followed biphasic pattern similar to that of cardiac output: a small release between 2 and 12 h and larger, significant losses at 24 h. Although we originally proposed that hearts preserved with UWBDM for 24 h were well preserved (Langendorff model), we now show that poor function was obtained at 24 h. The difference was that in this study we used a more rigorous, isolated working rabbit heart model to test the function of the preserved heart, and this may be a better test of preservation quality.