TRACHEAL ALLOGRAFT REPLACEMENT - AN UNSUCCESSFUL METHOD

Replacement of the tracheal conduit remains a difficult and unresolved surgical problem. We present an experimental study of 20 pigs undergo ing replacement of the cervical trachea using glutaraldehyde (n = 5), glycerol (n = 5), lyophilized (n = 5) and cryopreserved (n = 5) pretre ated allogenic grafts (AGs). In the lyophilized group, a stainless ste el spiral endoprosthesis was used as stent. A segment of native trache a measuring 3.2 +/- 0.3 cm (range: 1 - 5 cm) in length and 1.4 +/- 0.0 2 cm in diameter was resected and replaced with AGs measuring 3.8 +/- 0.2 cm in length and 1.4 +/- 0.02 cm in diameter. Neither immunosuppre ssive agents nor steroids were given. Animals were followed up with we ekly bronchoscopy, and trachea and chest roentgenography. Those receiv ing glutaraldehyde AG (21.6 +/- 6.4 days) and lyophilized AG (19.5 +/- 7.8 days) had a longer survival than those receiving glycerol AG (6.8 +/- 0.3 days) and cryopreserved AG (5 +/- 0.5 days). At postmortem, g rafts were examined grossly and with light microscopy. The cause of de ath was always airway obstruction, and the underlying processes were: 1) collapse due to cartilaginous microscopic necrosis in cryopreserved and glycerol AGs; 2) necrosis of allograft which crossed the spiral s tent for lyophilized AGs; 3) granulation formation, tissue necrosis an d anastomosis leakage in glutaraldehyde AGs. Results demonstrate that passage of necrotic tissue across the grafts represent the common fail ure denominator, making the different AGs studied unsuitable for long- segment tracheal replacement.