MAXIMAL PRESERVATION TIME OF TRACHEAL ALLOGRAFTS

Background. Our objective was to study the maximal preservation time o f directly revascularized tracheal allografts in immunosuppressed pigl ets. Methods. Donor grafts were flushed with Euro-Collins solution (65 mL/kg at 4 degrees C) by simultaneous inferior thyroid artery and bro nchial artery perfusion through a 15-cm aortic segment and heterotopic ally implanted on their own vascular pedicle after 3 (group 1), 6 (gro up 2), 15 (group 3), and 24 (group 4) hours of static storage in Euro- Collins solution at 4 degrees C (n = 5 each). The animals were observe d for 4 weeks after transplantation and then sacrificed. Histologic ev aluation of the tracheal allografts was routinely done using specimens from open biopsies. Results. The overall length of tracheal grafts wa s 12.4 +/- 0.6 cm, and this variable was not significantly different b etween the four groups. Graft exocrine (mucous secretion) function beg an 1.3 +/- 0.5 days after transplantation in groups 1 through 3 but wa s absent in all group 4 grafts (p < 0.0001). All grafts in groups 1 th rough 3 were viable at the time of sacrifice and showed Little discern ible intergroup and intragroup histologic and functional (tracheal smo oth muscle contraction and relaxation) variations except for a signifi cantly higher (p < 0.001) incidence of rejection in group 3 allografts . In contrast, all grafts in group 4 became completely necrotic 4 days after transplantation (p < 0.001) despite full patency of all the vas cular anastomoses. Conclusions. These results demonstrate that trachea l allografts may be safely preserved for as long as 15 hours and that longer periods of ischemia are likely to result in irreversible allogr aft damage.