HETEROTOPIC PIG MODEL FOR DIRECT REVASCULARIZATION AND VENOUS DRAINAGE OF TRACHEAL ALLOGRAFTS

A macrosurgical technique of thyrotracheal harvesting and direct revas cularization with and without venous drainage in a heterotopic thyrotr acheal and immunosuppressed allograft in the pig model is described. H arvesting included en bloc cervicothoracic exenteration of the aortic arch and its supraortic trunks, anterior vena cava, jugular veins, sub clavian vessels, thyroid gland, cervicothoracic trachea, and esophagus . This technique conserves the tracheal arterial supply provided by ei ther the right or left subclavian artery, directly or indirectly via t he inferior thyroid artery, and venous return provided by the anterior vena cava, directly or indirectly via the descending cervical vein. I n recipients, implantation included (1) arterial end-to-end anastomose s of the proximal and postscalenic stumps of donor's subclavian artery to the proximal and prescalenic stumps of recipient's subclavian arte ry; (2) end-to-side venous anastomosis of the donor's anterior vena ca va to the recipient's brachiocephalic venous hunk; and (3) heterotopic implantation of the proximal and distal orifices of the grafted trach ea into the neck. Ten adult Large White pigs underwent direct revascul arization of a thyrotracheal allograft with (n = 6, group 1) and witho ut (n = 4, group 2) venous drainage. All grafts of group 2 exhibited a venous infarction, extensive inferior thyroid artery thrombosis, and ischemic and suppurative thyrotr acheal necrosis 1 to 2 days after tra nsplantation. In group 1, the length of the grafted trachea and number of rings were 9.75 +/- 1.5 cm and 22.1 +/- 3.3, respectively; ischemi c time was 236.3 +/- 338.3 minutes. Group 1 pigs were put to death 4 ( n = 4) and 3 (n = 2) weeks after transplantation. All tracheal grafts had histologically normal airway epithelium; isolated areas of necroti c ischemia of the chorion and submucosa lasted for the first 7 days af ter transplantation but disappeared after epithelial regeneration. Pre mortem angiograms showed that ah vascular anastomoses were patent. Gra fts were histologically normal at postmortem examinations and all but one had no rejection. This large animal model demonstrates that long t racheal allografts might be transplanted by means of this direct revas cularization and venous drainage technique.