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In the world of angioplasty, there are two types of stents: a drug-coated version and a bare-metal stent, which is sometimes simply called a bare stent or uncoated stent. Compared to a drug-coated stent, which slowly releases medicine that helps reduce the possibility that an artery will fill with plaque again, a bare stent simply performs its job of keeping an artery open after angioplasty. Bare stents were the first type of stent and have been used around the world for many years.
The stent plays an important role during and after angioplasty. During surgery, a cardiac surgeon uses a catheter to expand a small balloon in a blocked artery. This procedure helps widen that artery and break up the plaque that is causing the blockage. The surgeon then inserts the stent to prevent the artery from collapsing and becoming blocked again.
Bare stents, usually made of stainless steel, are formed in the shape of a mesh tube. The collapsible mesh construction allows a cardiac surgeon to thread the stent to the artery where it is needed and then prop it open to support that artery. The mesh stent conforms to surrounding tissue to hold it open for proper blood flow, and the stent remains in place permanently.
As the artery heals, new tissue grows around the bare stent to make it part of the blood vessel. During this healing process, and before the stent is completely covered by new cardiac tissue, flowing blood is exposed to the bare metal of the stent. Doctors typically give patients aspirin or other anti-clotting medication to prevent in-stent thrombosis during this healing period.
With the advent of drug-coated stents, many studies have been done to test whether uncoated bare stents or drug-coated stents help improve healing ad survival outcomes after angioplasty. Some researchers have found that in some cases, there is an overgrowth of scar tissue around bare stents that presents future problems for the patients. Other researchers have found that bare stents might be more useful in patients who are at lower risk for having an artery become clogged again.
Cardiologists developed the bare stent during the first decade that angioplasty was first being performed, from the late 1970s to the late 1980s. During the first angioplasty procedures, surgeons found that some arteries collapsed after being unblocked with a small balloon. Surgeons also found that over time, some unblocked arteries began to close up without explanation. The first bare stent was used in France in 1986 to try to overcome these problems and support artery walls. Over the years, manufacturers worldwide have improved the stent’s construction and flexibility.