Angioplasty Info and the Stent, Part 7
Installing Coated Replacements to Repair Stents Tested Better than Using Radiation
- Small mesh cylinders called stents, which doctors surgically implant to prop open clogged arteries, have a disturbing tendency to become blocked soon after they are inserted.
- Stents can be cleared, but the only approved treatment for keeping a bare-metal stent from clogging again is the application of radiation directly inside the blood vessel.
- Inserting a new, drug-coated stent inside the old one—like a sleeve inside a sleeve—keeps blood flowing better than the application of radiation.
- Millions of people with blocked coronary arteries have avoided heart-bypass surgery by undergoing angioplasty, in which a doctor inflates a balloon-tipped catheter into a blocked artery to clear the obstruction; however, angioplasty is only a temporary fix for many patients.
- The move to stents has been much more efficient, but within a few months after they are implanted, about twenty percent of bare-metal stents start clogging.
- The blockages are made up of cells and proteins similar to those that form a scab.
- Radioactive pellets inserted into a bare-metal stent impede cell growth and can keep blood flowing through the vessel more consistently than angioplasty alone; however, radiation is said to be cumbersome to use and expensive.
- In addition, radiation sometimes contributes to a blockage by exacerbating vessel damage at the edges of the stent.
- Drug-coated stents discharge their cargo slowly over several weeks, the period when the vessel is still traumatized from angioplasty and at greatest risk of forming a clog inside the stent.
New research has come up with a better way to stop the clogging of stents
- Two research teams randomly assigned 780 people with blocked bare-metal stents to have angioplasty followed either by insertion of a second, coated stent or by radiation at the stent site.
- The stent-in-stent approach has proven to be better. Only nine percent and eleven percent of stents laced with the drugs sirolimus (Rapamycin) and paclitaxel (Taxol), respectively, needed to be reopened during the two nine-month trials.
- In patients receiving radiation, roughly twice as many stents required reopening during that time. The companies that make the two drug-coated stents sponsored the trials.
- Coupled with earlier work, the new studies "establish the role of drug-[releasing] stents as the preferred treatment" for blocked bare-metal stents, says cardiologist Adnan Kastrati of the German Heart Center in Munich.
There is more information about angioplasty; as well as, the stent at the following links:
Angioplasty Info and the Stent, Part 1
Angioplasty Info and the Stent, Part 2
Angioplasty Info and the Stent, Part 3
Angioplasty Info and the Stent, Part 4
Angioplasty Info and the Stent, Part 5
Angioplasty Info and the Stent, Part 6