Combined heart-lung transplantation in the rat. Comparison of thoracic and abdominal operation techniques

Recently, we developed two techniques for the combined transplantation of heart and the left lung into the left hemithorax of rats. One technique, with two vessel anastomoses, comprised the microsurgical repair of aorta, anterior vena cava, and left main bronchus. With the other, single vessel technique, only the aorta and bronchus were anastomosed. In this study, we determined the function and histology of syngeneic and cyclosporine (CsA)-treated allogeneic grafts transplanted with both techniques, and compared the results with those of heterotopic heart-lung grafts transplanted with a previously described technique for transplantation into the rat's abdomen. The survival rate of rats operated with either of the thoracic transplantation techniques was high (83%). Lungs and hearts of the grafts functioned well for over two months and had normal morphology when the double vessel technique was used. With the single vessel technique, the function of the lungs started to deteriorate from the third postoperative week onward, probably secondary to congestion. The results of thoracic grafts were superior to those of abdominal transplants, where the nonventilated lungs--especially during immunosuppression--were frequently infected. We conclude that these new techniques for thoracic transplantation are most suitable for research of combined heart-lung transplantation.