In reply to Flinticus:
I used to sell these devices.
They are tiny cages which are placed during a procedure called a baloon angioplasty, a tiny baloon is inflated under controlled pressue inside the stent. They are inserted through the wrist or thigh using a guide wire to navigate into one of the three main arteries around the heart. Its guided under xray; a contrast is used to reveal the arteries to allow the cardiologist to see where to place the device.
Its quite a skill steering a tiny wire into these tortuous places but its a routine and regular procedure.
There are two main types, a drug eluting stent or a standard without drugs. In both cases the stent is used as a scaffold to open up the arties where lesions occur. There is micro damage of the arterial wall, which is a good thing because it contains the stent in place.
The problems occur when the body tries to protect itself from the foreign body and completely cover the stent and occlude the artery again. This results in in-stent restenosis. The drug eluting stent is the answer to that; the stent is covered by a polymer into which a drug, Paclitaxel or similar, is impregnated. This drug elutes over time and prevents the lumen closing up.
Post edited at 16:54