A stent is a tube made of metal mesh, that is inserted into an artery to help keep it open. Heart stents are placed during an angioplasty, and then left in place.There are two kinds of stents. Bare metal stents are the traditional kind, and solely made of metal. With these, there is a chance the artery can become blocked with scar tissue during the healing process.ith the combination of several long arteries, that may be stented along their entire lengths, and the possiblility of putting stents within stents, the amount a person can have is virtually limitless. Having a lot of stents, however, is never be a good thing.