A simple new model of physiologically working heterotopic rat heart transplantation provides hemodynamic performance equivalent to that of an orthotopic heart

Background: The widely used non-volume-loaded abdominal heterotopic heart t ransplant (NL) in rats undergoes atrophy after transplantation. Various tec hniques have been designed to load the transplanted heart because of its po tential immunological impact. Our aim was to create a volume-loaded heterot opic heart transplantation model (VL) capable of ejection and practical for routine studies. Using this model, we tested the hypothesis that VL isogra fts would retain myocardial performance comparable to native hearts (NH). Methods: Heterotopic hearts were transplanted using and end-to-side anastom osis between the donor's superior vena cava and the recipient's abdominal i nferior vena cava. The right ventricle loads the left ventricle (LV) via a direct anastomosis of the pulmonary artery to the left atrium. The LV eject s volume through an end-to-side anastomosis of the donor's aorta to the rec ipient's abdominal aorta. Hemodynamic data (systolic and diastolic LV press ures, dP/dt max and min, tau) were studied in-situ (at baseline and after a dding volume) and in a Langendorff perfusion system (at baseline and after stimulation with isoproterenol) 2 weeks after transplantation. Results: In situ systolic pressure and diastolic function of VL was superio r to NL, and P-adrenergic stimulated performance in the Langendorff perfusi on of VL showed hemodynamic performance equivalent to NH, unlike NL which h ad a diminished response. Conclusion: This technique results in a volume-loaded ejecting heart transp lant model that preserves anatomical structures. The VL can be evaluated in situ and after explantation in Langendorff perfusion system and may offer advantages if workload of the graft is of significance to the study perform ed.