Doctors Excited by 'Breakthrough' Heart Stent
"At the moment, many patients are still treated with
medicines, unless they have a [significant artery] blockage. Now, if you have a
safe device that really works -- the effectiveness of angioplasty is now over
90% -- [fewer] patients will go to surgery," Morice said.
With simple angioplasty, a balloon at the end of a long tube is
threaded through an artery in the groin. The doctor shimmies the probe up
through the patient's leg and right into the arteries of the heart, inflating
the tiny balloon at the spot where the vessel has narrowed. The balloon cracks
open the plaque and stretches the walls of the vessel. Then the balloon is
deflated and removed. In about 25% or 30% of patients, the arteries close up
To keep the vessel open, doctors often add a stent to the end
of the balloon catheter. Stents bring the rate of renarrowing down to about 15%
to 25% of cases.
It happens because the blood vessel wall is injured when the
stent is implanted. The area then becomes inflamed and new cells start to grow
to form scar tissue. The attempt to heal the wound becomes exaggerated and the
artery walls become so thick that it sometimes protrudes into the inside of the
mesh scaffold. This tends to happen within six months of the stent being
Doctors then have to stretch the blood vessel again, put a new
stent inside the existing one, or perform bypass surgery.
The new stent is coated with Rapamune, usually used to prevent
organ rejection in kidney transplants. It stops new cells forming without
impairing the proper healing of the vessel, dampens inflammation, and also has
The stent releases the drug, generically known as sirolimus or
rapamycin, over 45 days.
Johnson & Johnson, which developed the stent, said it
expects the device to be on the market in Europe next year and in the U.S. in
2003. The study was sponsored by the company.
This past spring, doctors have shown they can use radiation to
treat restenosis around stents. In fact, doctors had been so optimistic about
the procedure that they told WebMD that most cardiologists will be using
radiation to treat restenosis and prevent a recurrence.
The advantage of using this new stent, if it proves successful,
is that the initial renarrowing could be prevented and not even require the