A Stent is a small, expandable wire-mesh structure device in Inox 317L, Cobalt Chrome, Plastic or biodegradable material that treats coronary heart disease and other diseases in which vessels are clogged, by re-opening narrowed arteries.
Stents implantation is a common procedure, a stent is mounted on a balloon catheter and then introduced through the area of obstruction in an artery. The balloon is inflated to widen the vessel and relieve the blockage. The stent, now against the vessel wall, is working as a scaffolding and the balloon is deflated and retracted, leaving the stent behind. Some stents are also self-expandable, whit deployment activated by the surgeon with a mechanism using the delivery system.
The first stents were bare metal stents (BMS) and despite improvements on the design, material and introduction techniques, BMS were facing high in-stent restenosis, which occurred in 10-30% of all stents. Restenosis is the term used when an “unblocked” vessel is “blocked” again after the procedure, usually within the first year.
The introduction of drug-eluting stents (DES) in the early 2000’s was to address the issue of restenosis. A polymer and a drug is applied to the stent strut that will help reducing the rates of repeat revascularization. The polymer, attached to the drug, serves as a barrier so the drug can be released over a period of time, generally months.
DES or third generations stents relies on manufacturing methods like ultrasonic spray coating, dipping, air brush and deposition on the stent struts. The challenges that stent manufacturers are facing are complex because the solution must be applied with accuracy, repeatability and homogeneity. Furthermore, the process must be perfectly controlled to meet medical standards.