Treatment used to prevent
heart attacks found to be effective at lowering stroke
risk
BY KRISTA CONGER
A technique traditionally
used to prevent heart attacks may provide new hope for
people suffering from repeated, debilitating pre-stroke
symptoms, say Stanford physicians. By inserting miniscule
inflatable devices into partially blocked arteries in the
brain, the researchers are able to gently stretch the
vessel walls and increase blood flow to oxygen deprived
regions. The procedure can alleviate transient ischemic
attacks, which frequently signal an impending stroke, and
decrease the likelihood of permanent neurological damage.
In a new study of the
procedure, more than 90 percent of the 23 patients
treated responded favorably, resulting in a marked
decrease in the group's annual rate of strokes over a
three-year period, according Michael Marks, MD, associate
professor of radiology.
"Not only has there
been a low rate of stroke, but none of the patients that
we're aware of today have had repeated symptoms of
transient ischemic attacks," said Marks, lead author
of the study that appeared in the May issue of the
journal Stroke. He believes that the results of the new
intracranial angioplasty treatment are promising enough
to warrant a controlled study comparing its success with
traditional medication for stroke-prone patients.
Strokes are the leading
cause of disability and the third leading cause of death
in the United States. The condition is caused by a
blockage in blood flow to the brain, either by a blood
clot that has migrated from another part of the body, or
by plaque that builds up gradually on the inside of an
artery. A stroke occurs when the blood flow is blocked
enough to cause long-term neurological damage or death.
Warning signs of an
impending stroke can include temporary muscle weakness,
difficulty speaking, dizziness or double vision. These
symptoms, known as transient ischemic attacks, or TIAs,
resolve themselves within minutes or hours. Severely
affected patients can suffer several attacks per day and
are unable to function normally. They are also much more
likely to suffer strokes, according to Marks.
"Strokes are
surprisingly common, particularly after a patient first
exhibits symptoms," he said. According to Marks, the
annual stroke rate for patients with blockage in the
cranial arteries is about eight to ten percent.
Standard treatments for
people who suffer strokes or TIAs include anti-coagulant
or anti-platelet therapy to inhibit further clotting in
the artery. However, some patients do not respond well to
medication and continue to have multiple attacks.
In the current study, a
group of patients whose symptoms were not alleviated by
medication were selected for the new angioplasty
procedure. The researchers used catheters and guide wires
to direct the uninflated balloons from the femoral artery
in the hip to the sight of the blockage in the brain.
Once in place, the balloons were slowly inflated over a
period of about 30 to 45 seconds to about two to four
millimeters, a diameter somewhat smaller than the
surrounding, unblocked regions. The balloons were then
deflated and withdrawn.
"The procedure is
designed to basically crack or injure the atherosclerotic
plaque and have it heal in a more open fashion,"
said Marks. A more open artery results in more blood flow
to the brain, he explained.
The procedure helped
decrease the degree of blockage from about 91 percent to
about 40 percent in 22 of the patients studied. One
patient died and one patient could not undergo
angioplasty because the balloon could not be properly
placed.
After the angioplasty
procedure, the patients were monitored for an average of
three years to determine the extended benefits of the
treatment. All remained on medication during the
follow-up period. Three years after treatment, the
group's annual stroke rate was 3.2 percent for strokes
occurring in the previously blocked region, and 4.8
percent for all strokes. That compares to an expected
eight to ten percent chance of stroke for patients
treated with medication alone.
"One of the most
rewarding experiences was that a group of patients that
were having repeated symptoms despite medication, some of
whom were literally bedridden, experienced complete
relief from symptoms of transient ischemic attacks,"
said Marks.
Balloon angioplasty has
become an accepted way to treat blockage in arteries near
the heart or in peripheral arteries feeding the limbs.
But using the balloons to treat blockage within the brain
is still relatively new. Researchers had to redesign the
balloons to be more easily guided and tracked during
their longer trip from the hip to the brain before they
could be used inside the cranium, according to Marks.
Even with the
improvements, the treatment is usually used only for
vessels at the base of the brain. Arteries more internal
are difficult to reach, and are usually responsible for
delivering blood to a smaller region of the brain, said
Marks.
Marks said the results of
the current study warrant further investigation and also
emphasized that the procedure is most appropriate for
people with especially severe symptoms.
"We are continuing to
do the procedure and are offering it to patients that we
think are at a high risk of stroke despite traditional
medical treatments," he said.
Marks' colleagues on the
study include Gregory Albers, MD, associate professor of
neurology and neurological sciences and director of the
Stroke Center; Gary Steinberg, MD, PhD, professor of
neurosurgery; David Tong, MD, assistant professor of
neurology; Alexander Norbash, MD, assistant professor or
radiology; and Mary Marcellus, RN, nurse coordinator of
the Stroke Center. SR
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