Heterotopic heart-lung transplantation: a new experimental model.

A new method of heterotopic heart-lung transplantation in the rabbit neck is described. Fourteen animals have received transplants with a view to studying the simultaneous histologic changes of early rejection. Seven animals have been treated with cyclosporine; a similar group of seven animals received no immunosuppressive therapy. Cardiac rejection has been characterized by a diffuse infiltrate of mononuclear cells progressing to myocyte necrosis and eventually to global infarction. In the lung the changes of rejection have been reflected especially on the vascular bed, with proliferative endothelial changes involving small- and medium-sized arteries often to the point of occlusion. There has been a striking lack of correlation between the severity of the lesions in the two organs. Prevention of graft rejection by cyclosporine has not been possible because of the susceptibility of rabbits to Pasteurella pneumonia. This new model also holds promise for the evaluation of graft function in acute situations.