Graft Contraction Phenomenon and Tracheal Stretching After Tracheal Replacement

Abstract

After cervical tracheal replacement (5 cm) using a bioabsorbable scaffold in a sheep model, Tsukada and coworkers [1Tsukada H. Gangadharan S. Garland R. Herth F. DeCamp M. Ernst A. Tracheal replacement with a bioabsorbable scaffold in sheep.Ann Thorac Surg. 2010; 90: 1793-1798Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar] observed a significant longitudinal contraction of the grafted area with tracheal approximation up to 75% at 9 months after surgery, in line with their previous results, by using aortic allografts (AAs). Therefore, they suggested that the observed graft shortening might allow for two-staged, end-to-end reconstruction of “large” tracheal defects after such temporary grafting techniques. We congratulate the authors for this contribution in the field of experimental tracheal surgery. Interestingly, by performing more than 200 tracheal replacements with AAs in a canine model, Pressman and Simon [2Pressman J.J. Simon M.B. Observations upon the experimental repair of the trachea using autogenous aorta and polyethylene tubes.Surg Gynecol Obstet. 1958; 106: 156-162Google Scholar, 3Pressman J.J. Simon M.B. Tracheal stretching and metaplasia of the tracheal rings from cartilage to bone following the use of aortic homografts.Am Surg. 1959; 25: 850-856PubMed Google Scholar] had already described the contraction phenomenon in 1958 to 1959, which led to stretching of the remaining tracheal segments. Consequently, the authors stated that this phenomenon “may be of sufficient magnitude to permit an end-to-end anastomosis, whereas this was not possible initially” [2Pressman J.J. Simon M.B. Observations upon the experimental repair of the trachea using autogenous aorta and polyethylene tubes.Surg Gynecol Obstet. 1958; 106: 156-162Google Scholar]. However, these recent and older landmark studies were restricted to replacements of the cervical trachea, and no relevant conclusion could be drawn as to more extensive tracheal replacements with AAs, such as we performed in a pig model (resection up to the thoracic inlet, down to the main carina) [4Makris D. Holder-Espinasse M. Wurtz A. et al.Tracheal replacement with cryopreserved, allogenic aorta.Chest. 2010; 137: 60-67Crossref PubMed Scopus (55) Google Scholar]. In our clinical practice [5Wurtz A. Porte H. Conti M. et al.Tracheal replacement with aortic allografts.New Engl J Med. 2006; 355: 1938-1940Crossref PubMed Scopus (102) Google Scholar, 6Wurtz A. Porte H. Conti M. Dusson C. et al.Surgical technique and results of tracheal and carinal replacement with aortic allografts for salivary gland-type carcinoma.J Thorac Cardiovasc Surg. 2010; 140: 387-393Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar], only 1 patient underwent limited (5.5-cm long) reconstruction of the central airway, after left carinal pneumonectomy. The other five patients underwent an extended tracheal resection (mean, 9.6-cm long; range 8.5 to 11 cm) including the carina in three [6Wurtz A. Porte H. Conti M. Dusson C. et al.Surgical technique and results of tracheal and carinal replacement with aortic allografts for salivary gland-type carcinoma.J Thorac Cardiovasc Surg. 2010; 140: 387-393Abstract Full Text Full Text PDF PubMed Scopus (81) Google Scholar], and the few remaining cartilage rings of the upper tracheal stump (mean, 2.8; range, 1 to 6) precluded a potential two-staged, end-to-end reconstruction. With a mean follow-up time of 48 months, in the 4 patients who were still alive, the observed graft shortening (mean, 50%) was actually insufficient to consider the staged procedure, as previously suggested [2Pressman J.J. Simon M.B. Observations upon the experimental repair of the trachea using autogenous aorta and polyethylene tubes.Surg Gynecol Obstet. 1958; 106: 156-162Google Scholar]. From a practical standpoint, in our series, the graft contraction phenomenon is currently evolving, precluding stent removal. To address this issue, we are currently investigating the construction of a tube-shaped graft from AAs reinforced by allogenic tracheal rings, with transferable vascular pedicle in a rabbit model, for more reliable replacement of the trachea in the future.