Graft function after heterotopic rat heart transplant with an isolated reperfused working heart: a methodic consideration

OBJECTIVES: Assessment of graft function in experimental cardiac transplant has been underused by insufficient methods (echo-cardiography, magnetic resonance imaging). The isolated reperfused working-heart model is an excellent tool for hemodynamic evaluation of rodent hearts. So far, it has never been used in a cardiac transplant setting. Our study tries to combine the in vivo technique of a rat heart transplant model with the ex vivo method of an isolated working heart.

MATERIALS AND METHODS: Heterotopic heart transplants have been performed in rats with a nonsuture cuff technique. After 8 hours of cold ischemia and 24 hours of reperfusion, grafts were mounted on the working heart. To assess graft function, cardiac output was measured with increasing levels of afterload pressure. Nontransplanted hearts were mounted directly to the working heart apparatus to serve as a control group. Each heart was assessed subjectively by the Stanford score before being mounted on the working-heart apparatus.

RESULTS: The working-heart assessment detected significantly impaired graft function in the transplant group compared with control hearts. In contrast, functional assessment with the score-system could not detect any difference between transplanted and native hearts.

CONCLUSIONS: The isolated working-heart model is an excellent tool for assessing graft function after experimental heart transplant in rodents.