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Recent innovations in
the treatment of stroke, including the new MERCI clot-retrieval
device, and improved imaging techniques, have opened
new windows of hope for stroke patients. Care is maximized
by fast-acting teams of professionals, like the Brain
Attack Team at University Hospital.
Apoplexy, the medical
condition now known as stroke, perplexed the ancient
Greeks. More than 2,400 years later, there’s still
no cure for stroke: It is the third leading cause of
death in America, and among those who survive, 15 percent
to 30 percent will be permanently disabled. That said,
advancements in medication, imaging, and endovascular
device technology—in the hands of dedicated stroke
teams—make the outlook for stroke patients dramatically
better than ever before.
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Picture of the MERCI Retriever System. |
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X-ray showing the MERCI Retriever
System after placement in a patient. |
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In the three short years
since the first
HealthLink article about stroke (November/December 2001),
giant steps have been made in the treatment and prevention
of stroke. Most recently, in August, the Food and Drug
Administration (FDA) approved the Merci Retriever, a
tiny corkscrew-shaped device that can remove blood clots
from the brains of people experiencing acute ischemic
stroke. (The most common type of stroke, ischemic, is
a blockage in an artery of the brain; a hemorrhagic
stroke, accounting for about 20 percent of strokes,
refers to bleeding in the brain.) The device, guided
to the blocked vessel via angiography, retrieves the
clot, restores normal blood flow, and is removed from
the body through a catheter. The Merci Retriever does
have limitations; for example, some clots are physically
beyond the reach of the device.
Nevertheless, says Dr.
Adnan Qureshi, a professor of neurology at New Jersey
Medical School and director of the stroke program at
University Hospital, the Merci Retriever is a welcome
addition to the treatment options University Hospital’s
Brain Attack Team (BATeam) has available for stroke.
“It’s a major step forward in the area of
devices, and having numerous treatment options is essential,”
he says. Physicians at University Hospital have already
trained with the Merci Retriever, and a protocol for
its use at the hospital is being developed.
Beat
the Clock
One word sums up the
challenge of stroke: time. Physicians are best able
to minimize the consequences of stroke—paralysis,
speech impairment, and cognitive difficulties among
them—if the patient is treated within three hours
of the onset of stroke symptoms. This timeframe isn’t
pulled from thin air. It’s when tissue Plasminogen
Activator (tPA), a clot-dissolving drug delivered by
an IV, is effective. As good as tPA is, it cannot be
used for every ischemic stroke patient for a variety
of reasons, including if the person is taking a blood
thinner or has had a stroke within the past three months.
Still, the most frustrating contraindication is time.
“Three hours can be very limiting because stroke
patients don’t usually rush right to the hospital,”
says Dr. Qureshi.
There is one way around
the tPA time constraints: deliver tPA directly to the
source of the problem. Using angiography guidance, an
interventional radiologist inserts a catheter at the
patient’s groin and navigates it to the blockage:
then, tPA is administered to the clot through the catheter.
Delivering clot-busting drugs this way extends the tPA
treatment window to six hours for some patients. However,
this specialized endovascular procedure—intraarterial
tPA—is only available at comprehensive stroke
centers, like University Hospital.
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| Angiogram
showing the microcatheter inserted into a blocked
artery prior to administration of the tPA. |
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One major concern physicians
have about the current generation of tPA is that it
can cause bleeding within the brain, especially in older
patients. They are turning to newer generations of thrombolytic
agents, either alone or in combination with other modalities,
to reduce this risk and offer potentially better outcomes
to patients.
For example, before Dr.
Qureshi came to University Hospital, he led a study
that combined the use of reteplase, a longer-acting
clot-buster, and balloon angioplasty or snares in high-risk
stroke patients. Low doses of reteplase were delivered
to a blood clot, which was then broken up mechanically.
Within this group of high-risk patients, one-third avoided
severe neurological deficit from stroke and were able
to live independently.
Scanning
the Possibilities
When brain cells are
deprived of oxygen, as occurs during stroke, they can
die within minutes. And yet, there are ways that physicians
can save precious minutes or even “buy”
time for stroke patients. One comes in the form of a
multidisciplinary stroke team, such as the BATeam at
University Hospital, that’s available 24-7 at
the call of a pager. The BATeam’s emergency room
physicians, nurses, neurologists, interventional neuroradiologists,
and technicians are well-versed in their respective
roles. “Everyone knows the sequence of events
and takes an urgent approach when a possible stroke
patient comes through the ER doors,” says Dr.
Qureshi. “Within 10 minutes, the patient is going
to get a scan.”
The team first assesses
the patient for stroke. That involves physical and neurological
examinations and, in most cases, a computed tomography
(CT) scan. CT, through computer technology and X-rays,
creates cross-section pictures that can indicate the
presence of abnormalities within the brain; namely,
bleeding, known as a hemorrhagic stroke, or blockage,
an ischemic stroke.
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Angiogram 3D reconstruction showing
area of intracranial arterial blockage. |
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Once a stroke is diagnosed,
the team needs more visual information of the affected
vessels. Angiography, considered by many to be the gold
standard, involves guiding a catheter to the area, injecting
a contrast dye into the vessels, and taking X-rays.
Another option, Magnetic Resonance Imaging (MRI), can
produce very precise images of brain tissue in special
sequences. As useful as these imaging techniques are,
they both have their disadvantages: Angiography is an
invasive procedure that can dislodge plaque within an
artery or dissect the vessel. Availability of the MRI
machine (most community hospitals have only one) and
the time it takes to develop images are two of this
imaging technique’s drawbacks when it comes to
stroke.
There is, however, another
imaging option that’s being used successfully
and more frequently with stroke patients. Computed tomography
angiography, or CTA, is a non-invasive way of imaging
the brain’s vessels. A dye is delivered intravenously,
and images are taken with a CT scanner equipped with
special software. CTA’s images are of a different
nature than angiography – being a snapshot versus
a video of sequential pictures taken over time—and
are not quite as precise as those captured by MRI, says
Dr.
Charles Prestigiacomo, an assistant professor of
neurological surgery and radiology at New Jersey Medical
School and director of neuroendovascular surgery. But
consider the factors of risk and time, and CTA has some
significant advantages.
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Dr. Charles Prestigiacomo |
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“A morbidly obese
patient came to University Hospital with symptoms suggestive
of a stroke. A CTA showed that the major blood vessels
of the patient’s brain were not blocked in any
way, and therefore, she was not having a stroke. Because
of CTA’s non-invasive nature, we were able to
get key information in a safer way,” says Dr.
Prestigiacomo. “For this patient, an angiogram
would have been very risky.” CTA’s major
risk is an allergic reaction to the dye, also a possibility
with angiography.
Another major advantage
of CTA is its speed. “With CTA, it requires only
about 25 seconds to take a scan, and then about 2 minutes
to process it,” says Dr. Prestigiacomo. “Depending
on the MRI sequence, it can take 25 to 30 seconds or
much longer to capture the images, and several minutes
of processing time. And that’s assuming the MRI
is immediately available. With stroke, every minute
counts, and that’s why CTA is such an important
imaging modality. It allows us to get important, potentially
life-saving information quickly, safely, and efficiently.
The extra minutes gained can save brain.”
From
the Heart
Imitation may be the
sincerest form of flattery; in the treatment of stroke,
it can also be lifesaving. Before tPA was used to dissolve
clots in the brain’s arteries, cardiologists used
it with heart attack patients. Similarly, some of the
endovascular devices that revolutionized heart surgery—balloon
catheters and stents—now are being used in the
brain’s vessels. Although tinier than their cardiac
counterparts, they perform the same jobs: balloon catheters
to open blocked vessels and stents to reinforce vessel
walls. Another type of device, coils, are used to clot
bleeding vessels.
Endovascular procedures
for stroke patients can be as effective as “open”
surgeries, but with the benefits of a minimally invasive
approach. As part of the national Carotid Revascularization
Endarterectomy versus Stent Trial (CREST), Dr.
Robert Hobson, a professor of surgery at New Jersey
Medical School, compared the use of catheter-delivered
stents and the traditional surgical removal of plaque
within the carotid artery. The carotid arteries, located
on either side of the neck, deliver blood to the brain.
Over time, plaque buildup can interfere with blood flow
or block a carotid artery, causing a stroke. Removal
of plaque within the carotid artery can reduce a person’s
risk of stroke.
In Dr. Hobson’s
study, the subjects were older patients at high risk
for stroke. Fewer than three percent of the patients
who underwent stenting had a stroke or died within a
month of the procedure, leading Dr. Hobson to conclude
that the minimally invasive procedure was both effective
and less risky than other preventive treatments.
The
Role of Research
When stroke patients
are able to resume regular routines and live at home,
it’s in large part because of the contributions
made by researchers. Dr.
Patrick Pullicino, chair of neurosciences at New
Jersey Medical School, is lead investigator of a 70-site,
$30 million National Institutes of Health (NIH) study
exploring the relationship between heart failure and
stroke. “I’m very interested in developing
this new area of neurology and cardiology,” says
Dr. Pullicino. He discounts the commonly held idea that
cardiac care belongs to the cardiologist and stroke
is a matter for neurologists, because when it comes
to stroke, the two are interrelated. Blood clots or
plaque can break off from within the heart, be carried
by blood flow, and block the tiny vessels in the brain,
causing a stroke.
The Zeenat Qureshi Stroke
Research Center at New Jersey Medical School, led by
Afshin Andre Divani, Ph.D., is engaged in several projects
related to stroke. “Clinicians bring us problems
they deal with each day, and our basic scientists work
to solve them,” says Dr. Divani. The stroke research
center is engaged in an extensive research strategy
involving epidemiological, clinical, and basic science
research pertaining to cerebrovascular diseases. “Effective
research needs to be conducted at all levels to develop
meaningful treatments for stroke,” says Dr. Divani.
“The more we understand the pathogeneses of cerebrovascular
diseases, the better we can develop prevention and treatment
strategies to combat this devastating disease.”
One real-world problem
is, that despite a medical team’s best efforts,
stroke can damage brain cells. The research center is
exploring the use of hypothermia (reducing body temperature)
to slow the brain’s metabolism and maximize the
recovery potential for brain tissue. The researchers
are also investigating whether neurological recovery
could be improved by using stimulating factors to increase
the presence of stem cells without the need of direct
implantation of stem cells at the affected area in the
brain.
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Afshin Andre Divani, Ph.D. |
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In addition, the Zeenat
Qureshi Stroke Research Center is leading a multicenter
NIH trial that studies the issues of blood pressure
control in patients with hemorrhagic stroke. The study
will evaluate therapeutic intervention in a group of
patients with very high death rates. The image analysis
facility in the center is used by several multicenter
studies funded by the NIH.
The group also works
with private companies and other academic institutions
in the testing of stroke-related devices. “One
collaborative effort”, says Dr. Divani, “assesses
how clot-retrieval devices effect or injure the blood
vessel walls.”
“Our ultimate goal
is not only to save the lives of stroke patients, but
also to improve the quality of their lives through our
innovative research,” added Dr. Divani.
“Brain
is Everything”
By the time most stroke
victims come to the hospital, the window of opportunity
is slamming shut. It’s then the job of stroke
specialists, such as those at University Hospital, to
utilize other treatments to prop the window open.
“The saying is
‘time is brain.’ I add, ‘and brain
is everything’,” says Dr. Qureshi. “I
am convinced that stroke will no longer be an untreatable
disease, and clinicians and researchers at New Jersey
Medical School and the Stroke Research Center will make
important contributions toward reducing the associated
death and disability.”
To
learn more about the prevention, diagnosis and treatment
of stroke, visit the Stroke Center at University Hospital
website at www.TheUniversityHospital.com/stroke
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