Percutaneous Coronary Intervention (PCI) (cont.)
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What is a stent?
A stent is an extendable metal scaffold that can be used to keep open previously narrowed coronary arteries after angioplasty has been performed. The mechanism used to place the stent in a narrowed or blocked coronary artery is very similar to balloon angioplasty. The difference is that the un-extended or collapsed stent surrounds the balloon. The stent surrounding the balloon is expanded when the balloon is inflated (see previous diagram). After the stent surrounding the balloon extends, it locks into place against the plaque/arterial vessel wall. The stent stays inside the artery after the balloon is deflated. Stents are useful because they keep the coronary artery open when the balloon is deflated, preventing most arteries from narrowing again (termed elastic recoil) after the balloon is deflated. Recurrent narrowing (restenosis) sometimes may still occur after the stent is placed due to formation of scar tissue.
The newest stents are termed drug-eluting stents. These stents are covered in a drug that slowly comes off the stent and prevents cell proliferation (scarring or fibrosis) at the stent site more effectively than uncoated, bare-metal stents.
There are many other stents beside coronary stents that are used for various other arteries and tissues. These include carotid artery stents (for stroke prevention), femoral artery stents, prostatic stents, esophageal stents, and many others.
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