Influence of surgical technique on the results of pulmonary reimplantation

Lung transplantation in the rat. III. Functional studies in iso- and allografts

Recently a microsurgical technique for orthotopic left lung transplantation in the rat was developed. The aim of this study was to investigate the influence of the operation itself and of an unmodified rejection reaction on the function of the transplanted rat lung. Orthotopic left lung transplantation was performed in 59 rats (34 isografts and 25 allografts). Isografts demonstrated a mean left lung perfusion of 23.1% in the first two postoperative weeks. Seven out of the 10 animals, subjected to a repeated scintigraphy 5-10 weeks later, had an increased graft perfusion, resulting in an almost normal mean left lung perfusion of 34.8%. At that time chest roentgenography revealed a good aeration of the grafts, that at autopsy had a normal aspect. Allografts showed an initial mean left lung perfusion (24.6%) similar to the isografts, which, however, declined sharply a few days later (4.3%). At that time chest roentgenography revealed totally opalescent grafts that at autopsy had the hepatized aspect characteristic of lung allograft rejection. These results of isogeneic and allogeneic lung transplantation in the rat were comparable with those of canine auto- and allotransplantation. For immunogenetic and economical reasons lung transplantation in the rat is a good alternative animal model in lung transplantation research.

Lung transplantation in the rat: II. lung perfusion scintigraphy in normal and left lung-transplanted rats

Lung perfusion scintigraphy with technetium 99m-labeled microspheres was performed in a series of 14 normal rats. The mean value of left lung perfusion was 36.9 +/- 4.9% of total lung perfusion. Duplicate determinations on three possible error levels were evaluated statistically: (1) separation of the lung fields on the computer scintigram, (2) positioning of the animal under the gamma camera, and (3) measurement after a one-week interval. The determinations resulted in standard deviations of (1) 2.8%, (2) 0, and (3) 1.4%, respectively. These results are comparable with those of lung perfusion studies in dogs. Lung perfusion scintigraphy, chest roentgenography, and postmortem examination were used in the functional evaluation of two groups of left lung-transplanted rats: Group A (n = 12) had short-term follow-up and Group B (n = 11) had long-term follow-up. A common finding in Group A was a subnormally perfused and aerated graft, showing normal lung tissue for the most part at postmortem examination. In Group B, grafts were rarely perfused and aerated. At postmortem examination, they were fibrotic or abscessed, possibly due to chronic rejection. A good correlation was found between perfusion scintigraphy, chest roentgenography, and postmortem findings.

Lung transplantation in the rat: I. Technique and survival

For immunogenetic and economical reasons, an operative technique for lung transplantation in the rat was developed. With the use of an operation microscope and 8-0, 9-0, and 10-0 sutures, the left pulmonary artery, vein, and brochus were anastomosed. The mean operation time was 4 hours; the mean graft ischemia time, 87 minutes. After frequent failures initially, due to anesthetic problems and lack of experience with microsurgical operative technique, a final peroperative survival of about 80% was obtained. Postoperative mortality approximated 50%. The main cause of postoperative death was thrombus formation at the site of an anastomosis. In a final series of 28 isogeneic transplantations, proper data for a one-month follow-up was obtained from 36% of the animals that underwent operation, a percentage comparable with initial canine pulmonary and rat renal transplantation studies. Left lung transplantation in the rat proved to be technically feasible and may provide an immunogenetically well defined and economically advantageous animal model in lung transplantation research.

Pulmonary reimplantation response

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