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Commentary: Toward a more ideal pediatric airway stent for tracheobronchomalacia

  • Roosevelt Bryant III
    Correspondence
    Address for reprints: Roosevelt Bryant III, MD, Heart Transplantation and Mechanical Circulatory Support, Phoenix Children's Hospital, 1919 E Thomas Rd, Phoenix, AZ 85016.
    Affiliations
    Division of Congenital Heart Surgery, The Heart Center, Phoenix Children's Hospital, Phoenix, Ariz
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Open ArchivePublished:April 18, 2020DOI:https://doi.org/10.1016/j.jtcvs.2020.04.035
      Figure thumbnail fx1
      CasMin Twine helical stent.
      • Lopez-Minguez S.
      • Serrano-Casorran C.
      • Guirola J.A.
      • Rodriquez-Zapater S.
      • Bonastre C.
      • DeGregorio M.A.
      New tracheal stainless steel pilot study: twelve month follow-up in a rabbit model.
      The helical Niti-S airway stent shows promise as a more ideal prosthesis for the management of tracheobronchomalacia.
      See Article page e51.
      The first clinical deployment of a pediatric airway stent was in 1988 and was reported by Loeff and colleagues.
      • Loeff D.S.
      • Filler R.M.
      • Gorenstein A.
      • Ein S.
      • Philippart A.
      • Bahoric A.
      • et al.
      A new intratracheal stent for tracheobronchial reconstruction: experimental and clinical studies.
      Since that time, an array of airway stents have developed to treat complex airway disease in children. Pediatric-specific applications of airway stents include use after tracheal reconstruction for congenital tracheal stenosis
      • Jacobs J.P.
      • Quintessenza J.A.
      • Botero L.M.
      • van Gelder H.M.
      • Giroud J.M.
      • Elliot M.J.
      • et al.
      The role of airway stents in the management of pediatric tracheal, carinal, and bronchial disease.
      and for tracheobronchomalacia
      • Furman R.H.
      • Backer C.L.
      • Dunham M.E.
      • Donaldson J.
      • Mavroudis C.
      • Holinger L.D.
      The use of balloon-expandable metallic stents in the treatment of pediatric tracheomalacia and bronchomalacia.
      not responsive to medical therapy. However, the ideal pediatric airway stent has yet to be developed. The ideal airway stent for pediatric patients should be easy to place, should support the airway without the development of significant complications, and should be easy to remove to allow maximal growth of the airway.
      • Jacobs J.P.
      • Quintessenza J.A.
      • Botero L.M.
      • van Gelder H.M.
      • Giroud J.M.
      • Elliot M.J.
      • et al.
      The role of airway stents in the management of pediatric tracheal, carinal, and bronchial disease.
      Potential stent-related complications include migration, granulation tissue formation, mucus formation, and infection,
      • Matt B.H.
      • Myer III, C.M.
      • Harrison C.J.
      • Reising S.F.
      • Cotton R.T.
      Tracheal granulation tissue. A study of bacteriology.
      particularly when granulation tissue develops. Despite the wide array (metallic,
      • Santoro G.
      • Picardo S.
      • Testa G.
      • Formigari R.
      • Marianeschi S.
      • Catena G.
      • et al.
      Balloon-expandable metallic stents in the management of tracheomalacia in neonates.
      silicon,
      • Nicolai T.
      Airway stents in children.
      bioabsorbable
      • Zajac A.
      • Krysta M.
      • Kiszka A.
      • Gorecki W.
      Biodegradable airway stents: novel treatment of airway obstruction in children.
      ) of pediatric stents available, none of them is ideal. The known complications associated with these devices have led to a stent-related mortality rate as high as 12.9%.
      • Nicolai T.
      Airway stents in children.
      Furthermore, the radial force used to keep certain kinds of stents in place has been shown to damage the microcirculation and serves as the nidus for mucosal injury and subsequent granulation tissue formation.
      • Roscoe A.
      • Kanellakos G.W.
      • McRae K.
      • Slinger P.
      Pressures exerted by endobronchial devices.
      ,
      • Frietag L.
      • Darwiche K.
      Endoscopic treatment of tracheal stenosis.
      In this issue of the Journal, Mondal and colleagues
      • Mondal A.
      • Ha J.
      • Jo V.Y.
      • Wu F.
      • Kaza A.K.
      • Dupont P.E.
      Preclinical evaluation of a pediatric airway stent for tracheobronchomalacia.
      present the results of a promising animal study looking at a novel airway stent, the helical Niti-S stent (Taewong Medical, Seoul, Korea), for the treatment of tracheobronchomalacia in children.
      • Mondal A.
      • Ha J.
      • Jo V.Y.
      • Wu F.
      • Kaza A.K.
      • Dupont P.E.
      Preclinical evaluation of a pediatric airway stent for tracheobronchomalacia.
      Its helical design is similar to the CasMin-Twine helical stent
      • Lopez-Minguez S.
      • Serrano-Casorran C.
      • Guirola J.A.
      • Rodriquez-Zapater S.
      • Bonastre C.
      • DeGregorio M.A.
      New tracheal stainless steel pilot study: twelve month follow-up in a rabbit model.
      used to treat canine tracheal collapse. The 2 types of helical stents share certain advantages. These include ease of deployment, limited mucus production, and focal mucosal changes limited to the areas of stent contact. The helical design provides radial support with substantially less mucosal contact and at a lower pressure. The results of the study by Mondal colleagues provide further evidence that the stent design provides less of a nidus for granulation tissue formation. This was also shown with the CasMin-Twine helical stent animal study. Where the 2 stents diverge is the novel removal tool associated with the helical Niti-S stent. Removal of the stent should allow optimal growth of the airway. A primary limitation of the study by Mondal colleagues is the short duration of therapy. After tracheal reconstruction for example, it can take 2 to 6 months for the airway to endothelialize.
      • Jacobs J.P.
      • Quintessenza J.A.
      • Botero L.M.
      • van Gelder H.M.
      • Giroud J.M.
      • Elliot M.J.
      • et al.
      The role of airway stents in the management of pediatric tracheal, carinal, and bronchial disease.
      It remains to be seen whether the helical Niti-S stent will be as amenable to removal with longer durations of therapy. However, the early advantages of the helical Niti-S certainly seem to be taking us toward a more ideal pediatric airway stent.

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