The emerging technology and expertise of endovascular therapy is expanding the treatment of carotid artery disease. Interventional radiologists have extensive experience in treating lesions in the noncoronary vasculature and possess the skills to treat disease of the common carotid artery bifurcation as well. Carotid angioplasty and stenting has shown beneficial results in the treatment of carotid atherosclerotic lesions. More in-depth studies are under way to compare stenting with carotid endarterectomy. Antiembolic neuroprotective devices are nearing Food and Drug Administration approval and may be capable of reducing procedural strokes and transient ischemic attacks. Patient and lesion characteristics optimal for carotid artery stenting are becoming better defined as more procedures are performed throughout the world. This article reviews the technique, outcomes, trials, neuroprotective devices, and guidelines for endovascular therapy of common carotid artery bifurcation stenosis.
Dr. Opp received his BS in Health Science at Walla Walla
College, College Place, WA. He completed medical school and
residency, and is currently completing a
vascular/interventional radiology fellowship at Loma Linda
University School of Medicine, Loma Linda, CA. In July 2001, he
will begin practicing with a private group servicing hospitals
in Puyallup, Tacoma, and Lakewood, WA.
Strokes affect approximately 600,000 Americans every year,
leaving a large number with permanent and significant morbidity.
Approximately 20% to 30% of strokes arise from debris that embolize
from carotid artery bifurcation atherosclerotic plaques.
Because the North American Symptomatic Endar-
terectomy Trial (NASCET)
and the Asymptomatic Carotid Atherosclerosis Study (ACAS)
showed morbidity reduction in patients who received carotid
endarterectomy (CEA), treatment of carotid atherosclerotic disease
has shifted from medical therapy to surgical intervention.
Carotid artery stenting (CAS) has emerged as a less-invasive
technique to treat stenoses of the carotid bifurcation; however,
stenting atherosclerotic lesions of carotid arteries may cause far
more devastating effects than those found in other vascular
territories. A small embolic shower to the leg or kidney may be
tolerated, but similar embolization to the brain may have severe
consequences. The very stroke to be prevented by surgery or
endovascular therapy may be precipitated by these procedures. The
morbidity of carotid stent placement is rapidly decreasing and has
been shown to carry risks of cerebral embolization similar to that
Many more than 5000 patients have been treated with CAS worldwide,
with a significant number in Europe, where new technology tends to
reach the market sooner.
More comprehensive randomized studies are under way.
Carotid artery stenting
At the 2001 Society of Cardiovascular and Interventional
Radiology (SCVIR) Annual Meeting, Dr. Michael H. Wholey, among
others, discussed the technique of carotid stenting. Thorough
preprocedure neurologic evaluation, including the National
Institutes of Health (NIH) Stroke Scale,
is performed. Next, a four-vessel cerebral angiogram and other
imaging are completed. Most commonly, patients are premedicated
with 325 mg aspirin qd and 75 mg Plavix (Bristol-Myers
Squibb/Sandofi Pharmaceuticals Partnership, New York, NY) qd for 5
After sedation, a femoral venous sheath is placed to facilitate
transvenous pacer placement if needed. A pacer may be placed
prophylactally in cases in which the lesion involves the carotid
bulb. (A pacer should be readily accessible, as reflex bradycardia
is seen with carotid angioplasty, especially of the carotid body.)
Common femoral arterial access is made and a 9F sheath is placed
prior to administration of 5000 units of heparin. Activated
clotting time (ACT) is kept at 250 to 300 seconds.
Access is made to the external carotid artery and an exchange
length stiff guidewire is placed. A 7F sheath or a guiding catheter
loaded with a 7F introducer (DVI, Temecula, CA) is advanced into
the distal common carotid artery, but not within 1 cm of the
lesion. After removal of the guidewire and introducer, appropriate
angiograms are obtained.
A 0.014-inch guidewire is advanced carefully through the lesion,
and the tip is stabilized at the level of C2. If the Food and Drug
Administration (FDA) approves a cerebral protective device designed
for internal carotid artery use, as discussed below, or if the
procedure is performed within a trial of these devices, then this
device would be positioned at this point, instead of a
A 3- to 4-mm X 2-cm Savvy balloon catheter (Cordis Corp.,
Warren, NJ) is positioned within the lesion, and 0.5 mg of atropine
is given. The balloon is inflated gently (not briskly), deflated,
and removed. Depending on the lesion's characteristics, a stent is
chosen. The SMART stent (Cordis) or Wallstent (Boston Scientific,
Minneapolis, MN) are two self-expanding stents used with excellent
results. Alternatively, a balloon expandable Palmaz or Corinthian
stent (Cordis) can be chosen. The stent is centered in the lesion,
and final positioning prior to deployment may be performed during
contrast injections through the guiding catheter or sheath. After
self-expanding stent deployment, the stent is dilated with a 5- or
6-mm balloon for internal carotid lesions.
Balloon expandable stents have the advantage of easier tracking
through tortuous arteries, greater precision in placement, and
greater radial hoop-strength, but are subject to external
compression deformation. Self-expanding stents have an element of
rebound to external compression andcan be sized to conform to both
internal and common carotid arteries. Stents are usually oversized
1 to 2 mm, and if deployed within both the internal and common
carotid arteries, they are sized to the larger vessel. Many stents
in development are better suited for carotid use, such as the
Precise stent (Cordis). It has a 5.5F deployment system, is quite
flexible, and has less friction during deployment, facilitating
precision of placement.
Patients are hospitalized overnight and continue taking aspirin
(which they must continue for life) and Plavix, 75 mg qd for 3
weeks. Postprocedure neurologic evaluation is performed and NIH
Stroke Scale is utilized at 24 hours, 1 month, and 6 months.
Figure 1 is an example of successful internal carotid origin
stenting with a SMART stent (Cordis).
Retrospective analyses of CAS
show excellent results comparable with CEA.
In comparing the complications of CAS, one must remember that
patients are often treated in spite of their greater medical risks
or having lesions that are not ideal for CEA.
Wholey et al
published the results of 114 consecutive procedures in which 108
carotid arteries were stented. There were 6 technical failures,
mostly due to tortuous atherosclerotic vessels that prevented safe
positioning of the guiding sheath. The 30-day stroke and death rate
was 5.3%, all occurring in symptomatic patients, with an additional
4.4% periprocedural TIAs. No antiembolic neuroprotective devices
were used in this study.
Roubin et al
reported on 604 consecutive carotid arteries treated by stenting.
The 30-day stroke and death rate was 7.4%. The major portion of the
30-day stroke and death rate was composed of minor strokes whose
rate was decreased by >50% during the additional 5 years of
experience gained during the study. A minor stroke was defined as a
neurologic deficit, which was new and either resolved in 30 days or
raised the NIH Stroke Scale by ¾ 3. A nonfatal, major stroke was
defined as a neurologic deficit, which was new and persisted >30
days and raised the NIH Stroke Scale by >= 4. The 3-year rate of
freedom from stroke and death in patients who survived the 30-day
periprocedural period was 95%. No neuroprotective devices were used
in this study.
Theron's experience spans decades.
Since stents became available in 1990, he has reported on 93
stenoses treated, with stents used in only 65. A distal 2.6F type
of occlusion balloon catheter was used during angioplasty, but was
removed for technical reasons when stenting was necessary.
(Technological advances now allow his type of protective device to
remain in place during stenting.) He had 2.2% periprocedural
emboli. These were treated with intra-arterial urokinase with
excellent results. His follow-up showed 4% restenosis in stented
carotids and 16% in those receiving angioplasty alone.
Carotid Revascularization Endar-
terectomy versus Stent Trial (CREST) is a large NIH-funded trial
comparing the efficacy, restenosis, and cost of carotid stenting
with CEA. Randomization of 2500 patients has begun, and additional
investigators are being sought. Investigators must pass through a
credentialing phase before they may enroll patients in the trial.
The Carotid Artery Vertebral Artery Transluminal Angioplasty Study
(CAVATAS) is a completed trial that is currently following patients
randomized between carotid or endovascular therapy and CEA in North
America and Europe. Several other trials are under way in North
America and Europe. The importance of these studies must be
underscored, as further comparison is needed.
Cerebral protective investigative technology
Significant amounts of debris can shower the cerebrum during
CAS. Anti-embolic devices will likely become standard during CAS
due to the potential reduction in periprocedural morbidity. Martin
evaluated the aspirate from 9 cases using protection by Theron's
technique. This showed cholesterol crystals and lipoid masses as
the major component of embolic material. The cholesterol crystals
ranged in size from 4 to 489 µm, and 115 to 8697 particles on
average were recovered. Lipoid masses ranged from 7 to 600 µm and
numbered 341 to 34,000. The amount of debris is likely an
underestimation, because the debris flushed into the external
carotid artery by saline before the balloon was removed could not
be recovered for analysis. This strongly suggests the need for
cerebral protection during CAS.
There are various types of cerebral protection, and some are
approaching FDA approval. At least three major types of devices are
being developed. The distal occlusion balloon, the distal filter,
and the proximal occlusion catheter are described below
1) A distal occlusion balloon interrupts distal internal carotid
artery blood flow, preventing cerebral emboli, which is an obvious
benefit; however, patients without a patent circle of Willis may
not be candidates for this type of device. The Guardwire
(PercuSurge, Sunnyvale, CA) is a promising example. A hollow, thin
shaft can be used as a guidewire after the detachable inflator is
used to inflate the distal balloon. Over the 0.014-inch shaft,
angioplasty and stenting is performed. Aspiration and flushing of
embolic material via the guiding catheter or sheath is performed
before the balloon is deflated and withdrawn through the stent.
2) A distal filter allows antegrade flow of blood, trapping most
emboli, and is removed at the completion of the procedure. Its
ability to permit cerebral perfusion while providing cerebral
protection is desirable. These devices must be inserted through the
carotid lesion and removed through the newly deployed stent. The
filters'relatively large size (3F to 5F) compared with other
devices is a drawback when crossing tight or friable lesions. As
with other devices in the field, size tends to diminish as
technology increases. One such filter is the AngioGaurd
3) A proximal occlusion catheter, such as the Parodi
Anti-Embolization Catheter (ArteriA, San Francisco, CA), is an
innovative concept. A balloon is located on the outside of a 7F or
8F guiding catheter in the common carotid artery, and an occlusion
balloon is advanced through the guiding catheter into the external
carotid artery. Both occlusion balloons are then inflated. Blood
flows retrograde from the internal carotid artery, through the
guiding catheter, where it is filtered and flows to a sheath in the
common femoral vein.
Stabilization of a device when in the distal internal carotid
artery must be achieved to prevent spasm or dissection. If spasm is
encountered, 100 µg of nitroglycerine may be administered
intra-arterially. When removing devices that are pulled through a
newly placed stent, care must be used so as not to dislodge or
In late 1999, 17 leaders in various fields involved in CAS met
in New York, and a consensus of their meeting was published in
The specialties represented were interventional cardiology,
interventional radiology, neurosurgery, and vascular surgery. They
report that the indications for CAS are:
1) Symptomatic patients with high risk factors or those who are
unfit for surgery;
2) Patients with recurrent stenosis;
3) Patients with a history of radical neck surgery or local
4) Patients with high common carotid bifurcation.
Most of the participants believed that CAS was indicated in the
presence of contralateral carotid occlusion.
Contraindications to CAS were stated to be:
1) Thrombus within the lesion;
2) Complex lesions containing multifocal disease or an angulated
3) Severe tortuosity or calcification of the great vessels or
extensive atherosclerotic plaque involving the arch or great
4) Common carotid bifurcation containing heavy ring-like
5) Stroke within 3 weeks or neurologically unstable.
Many of the participants stated that CAS should be limited to
high-risk patients until randomized studies are completed. It was
noted that most experts believe that neuroprotective devices should
be used when available. Intra-arterial fibrinolysis must be
available during and immediately after the procedure.
Carotid angioplasty and stenting is a less-invasive technique to
treat stenoses of the common carotid bifurcation. Stenting
noncoronary arteries is accomplished by interventional
radiologists, and similar skills are required to treat the common
carotid bifurcation. CAS has complication rates comparable to CEA
but lacks long-term follow-up of randomized patients; this process
is currently under way. Antiembolic neuroprotective devices are
rapidly approaching the market in the United States and are already
used abroad and in controlled studies in this country. Patient and
lesion selection are becoming more defined. In certain high-risk
patients, treatment by CAS may be the procedure of choice. Its
exact role in the overall treatment of carotid artery occlusive
disease remains to be clarified. *