Procedure to Open Blocked Arteries May Cause Damage to Blood Vessel
Nov. 15, 1999 (Cleveland) -- Stents, the tiny wire mesh tubes that are
threaded into blocked arteries in the heart and then expanded to create a
free-flowing passage for blood, have rapidly surpassed balloon angioplasty as
the technique of choice to open blocked arteries. Now, however, a small study
from Canada suggests that the stents themselves may damage blood vessels.
The researchers compared three different treatments to open blocked arteries
in the heart, and stenting was the only one associated with damage to the
lining of the vessels. The other two procedures -- balloon angioplasty and
directional atherectomy -- were not associated with damaging blood vessels,
according to the study, which is published in the Nov. 15 issue of Journal
of the American College of Cardiology.
In balloon angioplasty, a tiny deflated balloon is threaded through the
heart to the location where a vessel is blocked. The balloon is then inflated,
and the inflation forces the vessel open. The third method, directional
atherectomy, uses a device with tiny rotating blades. The device is loaded on a
catheter and threaded through the blood vessels; when it encounters a blockage
the operator activates the blades, which then slice away at the fatty plaque
that is blocking the artery.
The researchers tested 12 patients who had received stents, 15 who had
balloon angioplasty, and 12 who were treated with directional atherectomy. The
team assessed patients more than a year after they had undergone the procedures
to open a single vessel. Patients were given a drug, Miochol-E
(acetylecholine), that causes damaged vessels to constrict or spasm.
Co-researcher John D. Parker, MD, says that only patients who had undergone
stenting responded with significant constriction. "If this is clinically
relevant is unclear," he tells WebMD. Parker is an associate professor of
medicine at Mount Sinai Hospital at University of Toronto.
In an editorial accompanying the study, Gregory D. Tilton, MD, writes that
the group receiving stents had twice as much spasm further down in the blood
vessel away from the previous blockage than did the other two groups. Tilton is
a clinical instructor at Louisiana State University Health Sciences Center in
New Orleans. "Most studies are looking at the effects of stents on the
artery at the point the stent is implanted. We have a lot of those studies, but
this is a novel study," he tells WebMD.
Although the number of patients in the study was small, Tilton says the fact
that so many of the patients receiving stents had the same damage to the blood
vessel makes it interesting. "If the stent itself is doing this we need to
know if this is real." He says that the presence of a foreign object -- in
this case the stent -- may cause the body's immune system to overreact. This
reaction, he says, may cause damage to the vessel lining.
If a stent does cause these changes in blood vessels, the next issue is
finding out what effect the changes have. "Is it possible that this could
lead to angina ... ?" Tilton asks.
Tilton says, however, that there is no need for alarm because with so many
stents placed in recent years, enough time has passed that cardiologists would
already be talking among themselves about postprocedure problems. He says there
has "been no outpouring of concern in the cardiology community about
Parker agrees with Tilton and says that he, too, is unaware of any rising
concern among cardiologists.