How do those stents work?

I get this question a lot when I tell people I have stents in my coronary arteries. It is difficult to explain since I was pretty much like everyone else, I knew what happened from a patient's standpoint but I wasn't sure of the mechanics so I did some research.
I looked all over the place for good information on the placement of stents and was amazed at the lack of good information. I even looked at Stanford University's web site thinking that they at least would have some good visual representations. They didn't. I kept looking and I found a great web site with information on how and why the stents are placed along with information for people that may be thinking of getting stents. It is the National Heart Lung and Blood Institute web site. This image is from the site and shows what the artery looks like with plaque blockage and the various steps of placing a stent. (Click on the image to see a larger version) The site has a great little video that shows the placement procedure except for one huge difference. In the video there is a bandage placed over the groin site to stop the bleeding, but in all six of my experiences I have had a nurse pull the sheath out and place enormous pressure on the wound with a hand to stop the blood flow. This pressure is held for about 30 minutes and is really painful! After the sheath is pulled and the bleeding stopped you need to lay still and not move that leg for 4 to 6 hours before you can even attempt to get comfortable.

One of the things that I had trouble with this last time was a tear in an artery. I was really confused about that one until the doctor explained it visually. I thought the artery would tear like a run in panty-hose and that every time I heard of a tear in a blood vessel it was like a big rip, but I was wrong. It seems that an artery tears not with the length of the artery, but across it and there are layers of the arteries which tear. The tear does not go all the way from the inside to the outside but remains in a layer of the artery. Here is a good picture of a tear from inside the artery to give you a good idea. The tear can then catch the blood as it is pumped and stop the blood flow. Dr. Filardo explained this by rolling up a paper towel and then folding in the innermost layer forming a pocket, you can see how it would catch the blood flow and act as a sort of valve not allowing the blood to go any farther. This is the perfect use for a stent. It can be placed to push the tear closed and allow for the blood flow to go on past the site with no resistance. That's what the doctor had to do for me. Pretty cool isn't it?