Effect of simultaneous lung transplantation on heart transplant survival in rats.

Clinical observations in humans reveal that heart-lung transplant recipients suffer significantly less cardiac rejection than those receiving only heart transplants. A heterotopic combined heart-lung model in rats was used to test the hypothesis that the presence of the lung in this combination increases survival of the heart transplant. Cardiac survival was compared between en bloc heart-lung transplants and heart transplants. Low dosages of cyclosporine were used to prolong but not prevent the rejection process. Heart graft survival in the cyclosporine, 1 mg/kg/day, groups was significantly prolonged in heart-lung allografts. Histologic studies also demonstrated more advanced rejection of the heart in the heart-only transplant groups as compared with the heart-lung transplant groups. This study shows that the presence of the lungs in heart-lung allografts provides for prolongation of cardiac survival.