Doctors Excited by 'Breakthrough' Heart Stent
"I'm impressed," said Dr. Karl Karsch, head of cardiology at Bristol University in England, "but I'm always suspicious when the complication rate is zero. We have seen devices before that were very promising at this stage. Everybody was excited and it turned out that after two or three years there was a certain [relapse]."
Van der Giessen added that the rarely reported problem of contaminated (or infected) stents may get worse because the drug coating hampers the immune response.
More than one third of heart disease patients get angioplasty -- about 1 million people every year worldwide. Some patients have it done several times because their arteries keep renarrowing. An additional 700,000 people worldwide have heart surgery every year.
"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 again.
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 implanted.