USE OF OVER-SIZED MATURE PULMONARY LOWER LOBE GRAFTS RESULTS IN SUPERIOR PULMONARY-FUNCTION

Background. Mature lobar transplantation will increase the pediatric d onor organ pool; however, issues regarding size discrepancy between do nor grafts and recipient lungs remain unresolved. We hypothesized that an oversized mature pulmonary lobar allograft implanted into an immat ure recipient would provide adequate longterm pulmonary function versu s a size-matched mature lobar graft or an immature whole lung. Methods . We investigated our hypothesis in a porcine orthotopic left lung tra nsplant model in which 19 immature animals made up one control and thr ee recipient groups. Group I underwent sham left thoracotomy (control, n = 4). Group II received age-and size-matched immature whole left lu ng transplant (n = 6). Group III received mature size-matched left upp er robe transplants (n = 4). Group IV received mature over-sized left lower lobe transplants (n 5). Twelve weeks after implantation, data we re collected after the native right lung was excluded. Results. Graft weight was significantly elevated in group IV as compared with the exp lanted lung (72.4 +/- 6.8 versus 38.3 +/- 4.5 g; p = 0.003). Pulmonary artery pressure and pulmonary vascular resistance were significantly elevated in group III as compared with the over-sized mature lower lob e transplants (51.8 +/- 2.2 versus 40.4 +/- 2.5 mm tig [p < 0.0001] an d 1,605.9 +/- 117.5 versus 857.6 +/- 133.6 dynes.s.cm(-5) [p < 0.0005] , respectively). A trend toward decreased oxygenation was identified i n group II. Conclusions. Over-sized mature lobar grafts provide improv ed hemodynamics as compared with size-matched grafts. Mature left lowe r lobe grafts are superior to size-matched upper lobe grafts in this m odel, probably as a result of an augmented vascular bed. (C) 1997 by T he Society of Thoracic Surgeons.