REESTABLISHMENT OF LYMPHATIC DRAINAGE AFTER CANINE LUNG TRANSPLANTATION

The technique of pulmonary lymphoscintigraphy was used to evaluate pul monary lymphatic flow and to assess reestablishment of lymphatic drain age after lung transplantation. A first group of six control dogs unde rwent percutaneous transthoracic injection of a radiocolloid into the periphery of the left upper and lower lobes. Radiocolloids are large m olecules tagged with radioisotopes that are absorbed only through lymp h and are concentrated in tributary lymph nodes. Twenty-four hours aft er injection the dogs underwent scintigraphic studies of the chest and upper part of the abdomen. Mediastinal lymph nodes were visualized in all animals. A second group of four dogs underwent partial reimplanta tion of the native left lung, with interruption of all lymphatic conne ctions between the lung and mediastinum. Lymphoscintigraphic studies o f the left lung were obtained on the third postoperative day and then weekly for 4 weeks. Three of the four dogs in this group did not have visible mediastinal nodes 3 days after the operation. Nodes were visua lized in all animals at 1 week and at all following studies. A third g roup of five dogs were subjected to left lung allotransplantation by m eans of standard surgical techniques, as well as immunosuppression. Th e animals were studied with radiocolloid injections and lung lymphosci ntigraphy at weekly intervals for 6 weeks. Mediastinal nodes were visu alized for the first time 2 to 4 weeks after the operation and at ever y subsequent study. We conclude that lung lymphoscintigraphy is a reli able technique for the study of pulmonary lymphatic flow. This experim ent demonstrates that lymphatic drainage after lung transplantation is reestablished as early as the second postoperative week.