How does a stent open out when itís put in there?
Sun, 12th Aug 2007
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from the show Summer Special Naked Science Question and Answer
John, Peterborough asked:
I was watching a programme the other day about lining the arteries when you have a problem with them. How does a stent open out when itís put in there?
When youíve got a blocked coronary artery for example in the heart, what people used to do was to stick a line in through the top of the leg, into the artery, thread it back to where the heart is, go into the blood vessels supplying the heart and then you inflate a tiny balloon inside the artery. This opened up the artery by squashing the blockage which was making the artery narrow.
When they did that to start with, what would happen is, very quickly the artery would block up or fur up again. So then doctors discovered that the best approach is you if you deploy whatís called a stent, which is like a metal scaffold. Now itís very very tiny when you first put it in and itís threaded over the end of the balloon and when it gets to the right point in the artery where you want to deploy it, you inflate the balloon which stretches the scaffold. Itís almost like it ratchets out and locks in position. It props open the wall of the artery, stopping it constricting again and this should hold the problem area open and make sure it doesnít block again.