EXPERIMENTAL-MODELS OF TRACHEOBRONCHIAL STENOSES - A USEFUL TOOL FOR EVALUATING AIRWAY STENTS

Background. Stent implantation is a conservative alternative to open o peration for treating benign tracheobronchial strictures. Most of the presently available stents were primarily designed for endovascular us e. Their respiratory use entails a risk of iatrogenic complications. F rom a scientific and from an ethical point of view these risks justify preclinical evaluation of new respiratory stents in experimental mode ls of central airway stenoses. Therefore, an attempt was made to devel op such models in piglets and adult minipigs. Methods. Tracheal stenos es were obtained by creating first a segmental tracheomalacia through extramucosal resection of cartilaginous arches. The fibrous component of the stenoses was then obtained through bronchoscopic application of a caustic agent causing progressive deep mucosal and submucosal injur y. Stenoses of the main bronchi were created by topical application of the caustic agent only. Results. These models demonstrated the typica l features of benign fibromalacic tracheobronchial stenoses with const ant recurrence after mechanical dilation. Preliminary experiments show ed that short-term problems of tolerance of stent prototypes are easil y demonstrable in these models. Conclusions. These experimental models , which simulate quite realistically human diseases, offer the opportu nity to perfect new tracheobronchial stents specifically designed for respiratory use and to evaluate their longterm tolerance before their use in humans.