RECENT ADVANCEMENT IN AIRWAY SELF EXPANDING METALIC STENT (SEMS) DELIVERY SYSTEMS
These certainly must be exciting times for interventional pulmonologists. New innovations in airway stents and stent delivery systems are currently being developed and introduced for clinical use. The majority if these newer systems utilize flexible bronchoscopy. Advancements in delivery device sophistication, lower diameter profiles, rigid guidewires with “floppy” tips and the introduction of radiopaque catheter markers have resulted in new features including ease of deployment with less airway mucosal trauma and better placement precision in traditionally difficult anatomic locations further down the respiratory tree.
The flexible Over-The-Wire (OTW) lower profile (7.4mm) delivery catheters, such as with the Merit Endotek AEROstent, allows for single-handed deployment of a pre-loaded fully covered SEMS into traditionally difficult anatomical locations.
Through-The-Scope (TTS) delivery systems, such as the with the Merit Endotek AEROmini, also for deployment of fully covered SEMS, are another newer flexible system innovation designed to accept smaller diameter SEMS, which allow for stent deployment in more distal, tortuous and shorter segments of the tracheobronchial tree. The TTS system requires a working channel with diameters as small as >2.8mm for use. Additionally, they’ve produced a through-the-stent direct visualization delivery system (not to be confused with their TTS system) allowing for bedside deployment without the need of fluoroscopy for accurate stent placement.
Thoracent has recently devised an ultra-thin coaxial delivery system for their Bonastent, with some of their smaller sized catheters able to pass through the working channel of a flexible therapeutic bronchoscope, as well. The Bonastent delivery device allows for use of a <=0.035 inch guidewire. This system also possesses a stent recapturing feature allowing for immediate retrieval at up to 70% of stent deployment.
Atrium has recently introduced a balloon-expandable covered stent, the iCast, which employs a pre-mounted, multi-lumen delivery catheter comprised of both a primary wire and secondary inflation lumen. The iCast deployment system may be utilized through a working channel of >2.8mm, allows for a <=0.035 inch guidewire and has shown early reports of ease of deployment to compliment the stents increased flexibility and radial strength[29957039].
Recent advancement in guidewires has resulted in new delivery product designs as well.
Boston Scientific’s Amplatz Super Stiff (>=0.038in OD) guidewire for use in deployment of their Ultraflex SEMS and Merit Endotek’s Maxxwire (>=0.035in OD), are both guidewires employing radiopaque markers for improved visualization, ultra-stiffness for increased control, lower profiles for improved passage through stenoses by malignant tumors, and extra “floppy” tips to minimize mucosal trauma during deployment and stent displacement during catheter withdrawal. Cho et al has reported utilizing the Maxxwire in deployment of two Atrium iCast balloon-expandable covered stents[29957039].
We will certainly be monitoring the literature for the first peer reviewed case studies and clinical trials regarding the applications and efficacies these products in the future.
LITERATURE CITED
Cho RJ, Zamora FD, Gibson H, Dincer HE. Successful Deployment of Two Balloon-Expandable Stents Using an In-Stent Bifurcating Approach. Ann Am Thorac Soc. 2018;15(7):884-886. doi:10.1513/AnnalsATS.201712-963CC
