Stents are now used in most angioplasties. They are spring-like metal devices about the size of the spring of a ballpoint pen. When putting a stent, the blockage may be first opened up with a balloon. Then a stent, tightly mounted on an angioplasty balloon is positioned or the site of the blockage. When the angioplasty balloon is inflated, it opens the stent against the walls of the coronary arteries. The stent locks in this position, keeping the artery open. Finally, the balloon catheter is removed from the body. Once the stent is expanded or ‘opened’, it will never collapse to its original size.
Advantages of Stents:
Unlike plain balloon angioplasty, that with a stent mounted opens up the artery more widely.
The chances of a block recurring become less with the use of a stent. For example, consider an artery which has a block of 90%. After balloon angioplasty, the block will be reduced to 20-30 %. After stent implantation, the block will be nearly 0%. Thus, the block will be completely eliminated. Besides, when a blocked coronary artery is treated with the balloon procedure alone the chances of the blockage recurring are about 30% . But if a stent is implanted, the chances of the blockage recurring and causing symptoms drop to as low as 10% . So, using stents has become a necessary and routine procedure.
If after placing a stent the block does not recur in six months, the blocked artery stays open permanently. The chances of re-blockage of a stented artery in six months are 10%. So, stents can ‘cure’ most of the blocks if blockages do not recur in six months. However, patients have to take blood-thinner medicines for very long periods of time to prevent late clotting in these stents. Newer drug-coated stents are being developed to reduce this rare late clotting (thrombosis).
Drug Coated Stents:
With the progress of technology, better stents have become available. The new stents have a special type of coating of drugs like rapamycin or paclitexel. When these stents are deployed, they elute these drugs for variable times. They prevent swelling and proliferation (growth) of tissue around the stent. They also reduce the chances of re-blockage in the stented coronary arteries to as low as 2%. In the USA, in 90% of angioplasties such drug-coated or drug-eluting (coated) stents are used. People who receive drug-eluting stents should take aspirin lifelong as well as another blood thinner called Clopidogrel for over one year.