STRUCTURAL AND ULTRASTRUCTURAL-STUDY OF THE MYOCARDIUM AFTER 24-HOUR PRESERVATION IN UNIVERSITY-OF-WISCONSIN SOLUTION

This study deals with myocardial preservation after 24 hours of contin uous perfusion with University of Wisconsin (UW) solution, focusing on the morphological changes produced by preservation and reperfusion, a nd their possible relationship to the composition of the solution and the immediate hemodynamic findings after orthotopic heart transplantat ion in dogs. Following preservation, the histological images of the my ocardium were normal in almost every case. After revascularization, al though 50% of the hearts recovered preoperative functional levels, the re were relevant histological changes in all of them. These changes co nsisted of interstitial edema, damage to at least 50% of the mitochond ria, presence of contraction bands, loss of intercellular junction str ucture and vasoconstriction. According to these results, the associati on of continuous perfusion and UW solution appears to be effective dur ing the ischemic period of prolonged myocardial preservation, but not during reperfusion. Perhaps the proportion of viable hearts could be i ncreased by preventing vasoconstriction.