Initial 200 cases of carotid artery stenting using a reversal-of-flow cerebral protection device

Abstract

Because embolic complications can occur during carotid angioplasty and stenting (CAS), a new device, the Parodi Anti-Emboli System (PAES) was developed to protect the brain from embolization. We describe our initial experience with this device.
Between September 1999 and December 2003, CAS was performed in 200 consecutive patients (146 men; mean age, 70.4 years) with symptomatic (52%) or asymptomatic (48%) severe carotid artery stenosis (>70%). De novo lesions were present in 169 patients, restenosis in 18, and radiation-induced stenosis in 13. Wallstents were inserted in all cases, with selective predilatation, and the PAES was employed during all CAS procedures. Patients were evaluated by a neurologist before and after CAS. Minor strokes, major or fatal strokes, and myocardial infarctions that occurred within 30 days of the procedure were recorded.
The overall technical success rate for CAS using the PAES (with the PAES placed in position percutaneously) was 99%. The overall perioperative stroke and death rate was 1.5%. There were four transient neurologic events after CAS, three of which were related to hemodynamic instability and one to postoperative embolization.
Our experience indicates that CAS using the PAES is safe and effective. The protection device may prevent the debris released by angioplasty from entering the cerebral circulation. Additional studies of this device are warranted.

Full text

Initial 200 cases of carotid artery stenting
using a reversal-of-flow cerebral protection device
J. C. PARODI
1
, C. SCHÖNHOLZ
2
, F. E. PARODI
1
, G. SICARD
3
, L. M. FERREIRA
4
Aim. Because embolic complications can occur during
carotid angioplasty and stenting (CAS), a new device,
the Parodi Anti-Emboli System (PAES) was developed
to protect the brain from embolization. We describe our
initial experience with this device.
Methods. Between September 1999 and December 2003,
CAS was performed in 200 consecutive patients (146
men; mean age, 70.4 years) with symptomatic (52%) or
asymptomatic (48%) severe carotid artery stenosis
(>70%). De novo lesions were present in 169 patients,
restenosis in 18, and radiation-induced stenosis in 13.
Wallstents were inserted in all cases, with selective predi-
latation, and the PAES was employed during all CAS pro-
cedures. Patients were evaluated by a neurologist before
and after CAS. Minor strokes, major or fatal strokes, and
myocardial infarctions that occurred within 30 days of
the procedure were recorded.
Results. The overall technical success rate for CAS using
the PAES (with the PAES placed in position percuta-
neously) was 99%. The overall perioperative stroke and
death rate was 1.5%. There were four transient neuro-
logic events after CAS, three of which were related to
hemodynamic instability and one to postoperative
embolization.
Conclusion. Our experience indicates that CAS using the
PAES is safe and effective. The protection device may
prevent the debris released by angioplasty from enter-
ing the cerebral circulation. Additional studies of this
device are warranted.
K
EY WORDS: Carotid artery stenosis - Angioplasty, balloon.
E
mbolization to the brain is a universal occurrence
during carotid artery stenting (CAS) procedures,
as indicated by several well-conducted ex vivo stud-
1
Department of Surgery
Jackson Memorial Hospital
University of Miami, Miami, FL USA
2
Heart and Vascular Center
Medical University of South Carolina
Charleston, SC, USA
3
Barnes-Jewish Hospital
Washington University, Saint Louis, Mo, USA
4
FLENI, Buenos Aires, Argentina
ies,
1-3
routine transcranial Doppler monitoring (TCD),
and analyses of blood aspirated after use of distal
occlusion balloons. Thus, the goal of cerebral pro-
tection during CAS is to suppress or decrease the
number of particles or air bubbles that reach the brain
during the procedure.
Most reports have indicated that cerebral protection
during CAS is beneficial,
4-17
and numerous protection
devices have been described. Having used most of
these devices and recognizing their limitations, we
initiated an assessment of the safety and efficacy of a
novel cerebral protection device for use during CAS.
The functional principle behind this device is based
on an observation made on TCD during carotid
endarterectomy (CEA), that is, clamping the common
carotid artery (CCA) and the external carotid artery
(ECA) and inserting a shunt in the distal end of an arte-
riotomy induced flow reversal in the middle cerebral
artery (MCA) if the other end of the shunt was left
open to the air (Figure 1).
Initially, we applied the principle by creating a
small incision at the base of the neck; inserting a
short, 7F introducer in the CCA facing the lesion; and
occluding the ECA with a coronary balloon. The side
Juan C. Parodi and Claudio Schönholz are consultants for W. L. Gore
& Associates, Flagstaff, AZ, USA.
Address reprint requests to: J. C. Parodi, MD, 10988 SW 59 Ct, Pinecrest,
FL 33156, USA. E-mail: jparodi@med.miami.edu
Vol. 48 - No. 2 THE JOURNAL OF CARDIOVASCULAR SURGERY 117
ORIGINAL ARTICLES
J CARDIOVASC SURG 2007;48:117-24

PARODI INITIAL 200 CASES OF CAROTID ARTERY STENTING USING A REVERSAL-OF-FLOW CEREBRAL PROTECTION DEVICE
118 THE JOURNAL OF CARDIOVASCULAR SURGERY April 2007
port of the arterial catheter was then connected to a
side port of a sheath placed in the internal jugular
vein. Subsequently, we developed a long arterial
sheath with a balloon at its end to be used from a
femoral access (Figure 2). The design of the tip of
the catheter prevents trapping of particles around the
distal guiding catheter (Figure 3). The system also
includes an external balloon mounted in a hypotube
and a filter placed between the side port of the arte-
rial line and a venous sheath placed in the femoral
vein. The gradient between the internal carotid artery
(ICA) and the femoral vein produces flow reversal in
the ICA. Intermittent aspiration enhances flow rever-
sal during critical stages of CAS and before injection
of contrast media in the guiding sheath.
This flow reversal device became the Parodi Anti-
Emboli System (PAES; ArteriA, San Francisco, CA,
USA; Figure 4). The PAES is a closed system that
allows arrest of ICA flow, continuous passive ICA
flow reversal, or augmented active ICA flow reversal
so that any particles released during CAS will pass
retrograde through the catheter and be retrieved in the
arteriovenous conduit filter outside the body. The
three components of the device were designed specif-
ically to allow retrograde flow in the ICA and minimize
margination of particles or collection of material that
could subsequently embolize.
The first component, the Parodi antiembolic catheter
Figure 1.—Observation during open carotid endarterectomy using
transcranial Doppler (TCD) monitoring.
Figure 2.—First-generation reversal-of-flow system.
Figure 3.—Distal balloon of the reversal-of-flow system.
Figure 4.—The three components of the Parodi Anti-Emboli System,
which was designed to provide retrograde flow in the internal caro-
tid artery.

INITIAL 200 CASES OF CAROTID ARTERY STENTING USING A REVERSAL-OF-FLOW CEREBRAL PROTECTION DEVICE PARODI
Vol. 48 - No. 2 THE JOURNAL OF CARDIOVASCULAR SURGERY
119
(PAEC), is a 9.5F, 90-cm-long guide catheter with a fun-
nel-shaped balloon on its tip. This atraumatic balloon
allows occlusion of the CCA and flow reversal. It also
serves as the access port for the stent delivery system
and other therapeutic devices. The second compo-
nent, the Parodi external balloon (PEB), is a soft atrau-
matic oval balloon mounted on a 0.019-inch hypotube,
which is a low-profile hollow guidewire that allows
inflation of the balloon. The distal, shapeable, floppy
guidewire facilitates navigation into the ECA. The
third component, the Parodi blood return system
(PBRS) is a conduit that connects the side flow rever-
sal port of the PAEC to a venous sheath. The PBRS has
a 180 µm filter that collects particulate debris before
the blood reenters the venous system.
We report our experience with the PAES in 200
consecutive patients undergoing CAS.
Materials and methods
This study was approved by our institutional review
board, and all patients provided informed consent to
participation. Between September 1999 and December
2003, CAS was performed in 200 consecutive patients
(146 men; mean age, 70.4 years). All patients had CA
stenosis of greater than 70% (symptomatic, 52%;
asymptomatic, 48%). De novo lesions were present in
169 patients, restenosis in 18, and radiation-induced
stenosis in 13. The diagnosis of high-grade CA steno-
sis was based on duplex ultrasound scanning and
confirmed angiographically before CAS. All patients
were high-risk candidates for CEA because of one or
more of the following: history of congestive heart fail-
ure, coronary artery disease requiring coronary artery
bypass grafting (CABG) or percutaneous transluminal
angioplasty, severe chronic obstructive pulmonary
disease, renal insufficiency, first or second restenosis
after CEA, and hostile neck (Table I).
Beginning 3 days before CAS, patients received 325
mg of aspirin and 75 mg of clopidogrel per day, except
for the two patients who underwent combined CAS
and CABG. Symptomatic patients underwent com-
puterized tomographic (CT) scanning of the brain
before CAS. The CAS procedure was performed with
the patient under local anesthesia. The common
femoral artery and vein were cannulated percuta-
neously by using the Seldinger technique. A 10F
sheath was introduced in the artery and a 6F sheath
in the vein. An arch arteriogram was obtained with a
pigtail catheter in the left anterior oblique position. In
patients with a serum creatinine level above 2 mg/dL,
an arch study employing iodinated contrast media
was not done; instead, information about the anato-
my of the arch was obtained with use of magnetic
resonance (MR) angiography. Gadolinium rather than
iodinated contrast was used to visualize the arterial
branches after cannulation in those patients. The CCAs
were selected according to standard techniques. The
floppy wire used initially was exchanged for an
Amplatz super stiff wire (Boston Scientific, Natick,
MA) after insertion of the catheter in the ECA.
The PAES was positioned over the stiff wire. In all
cases, we demonstrated backflow by opening the
three-way stopcock located distal to the external filter
and immediately proximal to the venous sheath. We
applied additional suction with a syringe during the crit-
ical steps of the CAS procedure (crossing the lesion,
balloon deflation, and stent deployment). Additional
aspiration was also applied before a contrast injection
and immediately after the images were obtained. Flow
reversal was also documented directly by dynamic
angiography and Doppler monitoring (intracranial ICA
or MCA). TCD monitoring was used if available and a
temporal bone window was present for insonation.
The first step in obtaining flow reversal is placement
of the PAEC. This can be done by using any of the
accepted techniques for guide catheter placement in
TABLE I.—Demographic data and risk factors (n=200 patients).
Characteristic Value
Median (range) age, y 69 (55-83)
Sex (M/F) 146/54
Symptomatic disease 104
Previous stroke 22
Hemispheric TIA 31
Retinal TIA 6
Hypertension 185
Hyperlipidemia 171
Tobacco use (current or within previous year) 123
Diabetes mellitus 37
Symptomatic coronary artery disease 54
Previous coronary artery bypass 32
Previous PTCA 26
Coronary ischemia on cardiac testing 58
Congestive heart failure 17
Q-wave myocardial infarction 22
Contralateral ICA stenosis >70% 18
Contralateral ICA occlusion 12
Values are numbers of patients unless otherwise specified. TIA: transient
ischemic attack; PTCA: percutaneous transluminal angioplasty; ICA: internal
carotid artery.

PARODI INITIAL 200 CASES OF CAROTID ARTERY STENTING USING A REVERSAL-OF-FLOW CEREBRAL PROTECTION DEVICE
120 THE JOURNAL OF CARDIOVASCULAR SURGERY April 2007
the carotid artery. The PEB is then placed through
the dedicated proximal port of the PAEC and navi-
gated under fluoroscopic guidance into the ECA. The
third step is purging and attaching the PBRS to a 6F
venous sheath. The venous sheath can be placed in
the ipsilateral or contralateral femoral vein. After the
device has been positioned, the CCA is occluded with
the PAEC and the PEB is inflated in the ECA. Opening
the PBRS stopcock initiates continuous flow reversal
through the arteriovenous shunt. Patients are observed
for evidence of intolerance to flow reversal, which
may manifest as cloudiness of conscience, agitation,
hemispheric deficit, or seizure.
In this series, a Wallstent (Boston Scientific) was
inserted in all cases, with selective predilatation. The
Wallstent was dilated with a 5- or 6-mm-diameter bal-
loon. Half milligram of atropine was injected intra-
venously before balloon dilatation in every patient
with the exception of those with restenosis after
surgery. A final arteriogram with intracranial views
was obtained for every patient (Figure 5).
After the procedure, patients received 75 mg of
clopidogrel per day for 30 days and 325 mg of aspirin
for life. Independent neurologists assessed the neu-
rologic status of the patients before and after the CAS
procedure, including during a visit made before hos-
pital discharge. Data on the technical success of CAS
using the PAES; the patients’ duration of hospitaliza-
tion; post-procedure (within 30 days) strokes, deaths,
and myocardial infarctions (MIs); and other compli-
cations were compiled.
Results
The overall technical success rate for CAS using
the PAES in this series was 99%. High success rate is
due to anatomical selection of patients using MRA or
CTA. Patients with severe tortuous and calcified arter-
ies or very small vessels were excluded. The only
patient who could not be treated percutaneously was
successfully treated endoluminally by approaching
the proximal CCA through a 3-cm incision at the base
of the neck. Flow reversal was created after clamping
the CCA and connecting the side port of the arterial
introducer to the side port of a venous introducer
inserted in the internal jugular vein.
In all cases, particles of different sizes were recov-
ered in the interposed filter. TCD monitoring was
used in 132 patients, and no embolic signals were
registered during reversal of flow. In some patients,
TCD showed intracranial ICA or MCA flow reversal; in
others, there was sufficient collateralization from the
anterior cerebral artery. For 180 of the 200 patients,
hospital discharge occurred the day after the CAS pro-
cedure. Seventeen were discharged on the second
day after treatment. The three patients with serious
complications had a prolonged hospital stay.
The overall perioperative (30 days or in-hospital)
stroke and death rate was 1.5% (Table II). There was
one contralateral minor stroke after cardiac surgery
was performed concomitantly, one case of fatal hyper-
Figure 5.—Angiographic images of carotid angioplasty and stenting
with reversal of flow. A) High-grade stenosis of the internal carotid
artery. B) The balloons in the external carotid artery and the common
carotid artery are inflated. C) During flow reversal, the lesion is cros-
sed with a wire, predilated with a 4-mm balloon, and stented. D)
Post-procedural angiogram shows reestablishment of antegrade flow.
TABLE II.—Peri-procedure (within 30 days) end points (n=200
patients).
End point No. (%)
of events
Minor stroke (non corresponding) 1 (0.5)
Major stroke (intracranial hemorrhage) 1 (0.5)
Fatal stroke (intracranial hemorrhage) 1 (0.5)
Fatal myocardial infarction 1 (0.5)
Perioperative stroke/death 3 (1.5)

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perfusion syndrome, and one fatal MI. In the patient
with the minor stroke, symptoms had partly resolved
by 30 days after the CAS procedure. The stroke was
probably due to excessive catheter manipulation in a
patient with a type III aortic arch. Hyperperfusion
syndrome developed in a patient who was discharged
the day after CAS and readmitted 3 days later because
of severe headache. TCD indicated hyperperfusion.
Despite treatment, a massive hemispheric hematoma
developed and the patient died. The fatal MI was in
a patient who had prolonged hypotension and brady-
cardia that began during the CAS procedure. The MI
occurred despite an attempt to treat the cardiac
ischemia with coronary stent-assisted balloon angio-
plasty. The patient had a history of syncope and had
been given a diagnosis of hypersensitivity of the
carotid sinus.
Transient neurologic symptoms developed in four
patients (2%) during the perioperative period. In three,
the symptoms were related to hypotension; in the
fourth, they were due to postoperative embolization
24 hours after CAS. Each patient underwent TCD mon-
itoring and CT scanning to rule out emboli and infarc-
tions. In the first three patients, the symptoms resolved
as soon as the blood pressure returned to normal.
The fourth patient, who had two hemispheric transient
ischemic attacks (TIAs) in the recovery room, was
treated with dextran. TCD monitoring revealed
microemboli and 50 high-intensity transitory signals
(HITS) per hour. This resolved after 30 minutes of
treatment.
Early in the series, three patients had temporary
asystole during CAS, without sequelae. Bradycardia
occurred in 12% of patients and hypotension in 6%.
After we initiated a policy of discontinuing all anti-
hypertensive drugs the day before CAS, hypotension
was rarely observed. Minor groin hematoma devel-
oped in 10 patients, but none required a blood trans-
fusion or drainage.
Discussion
Many investigators consider cerebral embolization
the Achilles heel of CAS. Information provided by
TCD during CAS and the retrieval of particles by cere-
bral protection devices used in clinical trials indicate
that embolization is universal during the procedure.
8,
18, 19
Additional corroboration has been provided by in
vitro studies using CEA specimens.
1-3
The conse-
quences of cerebral embolization during CAS are not
yet completely understood, and findings in studies
of this issue probably depend on the sensitivity of
the assessment method used. In a study by Schlüter et
al.,
20
diffusion-weighted MR imaging (DWMRI) after
CAS in which filters were used for protection showed
a 22.7% rate of cerebral diffusion defects. New
ischemic lesions were observed on post-procedure
DWMRI in 10 patients, but only one had a major
stroke. None of the other nine patients had any
adverse neurologic deficits.
Cognitive studies, although inconclusive, have sug-
gested that the effects of cerebral embolization of
particles are not inconsequential. Gaunt et al.
21
observed significant cognitive changes in patients
with embolization (detected by TCD) of 10 particles
during carotid dissection as part of a CEA, but these
were not associated with adverse clinical outcomes.
Thus, “nonclinical” consequences of embolization
depend on the method used to detect them. In our ini-
tial study of CAS and carotid protection,
22
we observed
a trend toward an increased incidence of complica-
tions in unprotected patients (a 9.53% rate of neuro-
logic events in the unprotected group compared with
no events in the protected group). In the same study,
in which TCD was used routinely, we found that the
only protection system that produced no HITS during
the protected period was the PAES. However, it is
becoming evident that all protection devices provide
some degree of protection against cerebral emboliza-
tion. In an evaluation of a registry of CAS procedures,
Wholey et al.
4
found a 5.29% rate of stroke/mortality
in unprotected patients and a 2.23% rate in patients in
whom cerebral protection was used.
There are stages of CAS in which the brain is not
protected: while the arch arteriogram is being
obtained, during cannulation of the arteries, and dur-
ing advancement of the sheath inside the CCA. This
occurs with all protection devices, including the PAES.
In addition, devices such as the PercuSurge (Medtronic
Vascular, Santa Rosa, CA) or filters that cross the stenot-
ic lesion may disrupt or embolize material. Ohki et al.
23
reported that 12% of particles generated during an
in vitro procedure were produced during crossing of
the lesion. Another in vitro study found that crossing
the lesion produced more than 50,000 particles.
3
In
two studies of CEA specimens, thrombus lining the
carotid plaque was found in 24% and 48% of cases,
respectively.
24, 25
We have observed, as have Al-
Mubarak et al.,
26
that HITS occur throughout CAS pro-

PARODI INITIAL 200 CASES OF CAROTID ARTERY STENTING USING A REVERSAL-OF-FLOW CEREBRAL PROTECTION DEVICE
122 THE JOURNAL OF CARDIOVASCULAR SURGERY April 2007
cedures that use a PercuSurge device. It is clear that,
in such cases, particles travel to the MCA through the
ECA flow. We found that crossing the lesion while
using a filter produced showers of particles. HITS
also appeared in the TCD monitor throughout the
procedure, caused by particles crossing the filter or get-
ting around the filter. The typical pore size in filters is
120 µm. However, studies in animals found that par-
ticles larger than 50 µm can produce lesions.
27
In studies in vitro, filters were found to miss 2.3%
to 18% of particles injected proximally to the filters.
28
Moreover, the degree of tortuosity of vessels affects the
rate at which particles are captured. Jaeger et al.
29
reported that application of filters was problematic
in a high proportion of patients: predilatation was
required in 27%, repositioning of the filter was nec-
essary in 18%, and retrieval difficulties occurred in
7%. In some cases, a “buddy wire” was used to allow
advancement of the filter along a tortuous artery.
Filters may also fill with material that migrates when
the filter is retrieved. The stroke rate in clinical trials
in which filters have been used is still significant.
19
The
Stenting and Angioplasty with Protection in Patients
at High Risk for Endarterectomy (SAPPHIRE) trial had
a 30-day stroke rate of 3.8%,
5
and the ACCULINK for
Revascularization of Carotids in High-Risk Patients
(ARCHeR) trial had a rate of 5.3%.
8
Placement of balloons and filters in the distal ICA
can induce spasm and damage to the intima.
Dissections of the ICA have occurred with use of the
PercuSurge device. In contrast, the PAEC is a guiding
sheath with an occlusion balloon attached at the dis-
tal end of the catheter. The main lumen has an inner
diameter of 7F, which allows passage of balloons and
stents. After the PAEC is inserted in the CCA, the occlu-
sion balloon attached to the outer surface of the PAEC
and the ECA occlusion balloon are inflated, thereby
occluding inflow to the carotid bifurcation while main-
taining access to the carotid bifurcation lesion through
the main lumen. The side port of the PAEC is then con-
nected to a sheath that is inserted percutaneously into
the femoral vein to create a temporary arteriovenous
shunt. This shunt, along with the ECA occlusion by the
balloon, creates reversal of flow in the ICA. Particles
of all sizes will flow retrograde through the PAEC and
can be captured. Once reversal of flow is established,
CAS can be safely performed with use of the guidewire
of choice. The lesion is not manipulated with any
device until cerebral protection is achieved. Because
the PAES device provides cerebral protection before
crossing of the lesion, the risk of generation of embol-
ic particles and possible neurologic complications is
avoided.
The PAES device overcomes most of the problems
encountered with balloons and filters, including fail-
ure to cross the lesion, embolization during lesion
crossing, failure to capture all emboli, and detach-
ment of filter or balloon components. It has some
drawbacks, however. Its large profile requires the use
of large introducers (10F), and the 9F sheath for the
PAEC is somewhat bulky for navigation through tor-
tuous arteries. However, intolerance to balloon infla-
tion is much less common or problematic than what
may have been predicted. In our series, all proce-
dures were completed despite a 3% rate of clinical
intolerance. Intolerance to flow reversal was charac-
terized by cloudiness of conscience; one patient had
a temporary corresponding side hemi paresis, no
patient experienced seizures. Our approach to intol-
erance was: patients with mild cloudiness of con-
science continued to have the procedure. Patients
with stupor were treated in the following way: after
careful aspiration of the sheath, the common carotid
balloon was deflated; as soon as the patient recovered
a second inflation was performed. Because of the
phenomenon called pre-conditioning second infla-
tion was well tolerated. It is important to define the
anatomy of the circle of Willis in advance. Patients with
isolated middle cerebral artery should be treated with
filters or better, with the association of flow reversal
and filters as was described by us as the “seat belt-air
bag” technique.
37
Two patients who we not included
in this series were treated in this way.
Criado et al.
30
reported an intriguing study sug-
gesting that reversal of flow is better tolerated than bal-
loon occlusion of the ICA. They speculated that this
may be because flow reversal enhances collateral
flow to the circle of Willis. In any event, reversal of
flow in the ICA provides the operator with assurance
that no particles will migrate to the brain and that
lesion crossing and removal of thrombus from the
lesion will be safe.
Our results using the PAES compare favorably with
those in trials or registries of CAS performed in high-
risk patients,
31
although it should be noted that we did
not use troponin assessments to rule out acute MIs.
However, the stroke and mortality rate in our series is
somewhat lower than that in other series. Moreover,
other authors have reported results with the PAES
that are similar to ours. Adami et al.
32
described a sev-

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en-center, nonrandomized prospective trial of CAS
using PAES protection. The study included 30 patients
with 15 symptomatic (>70%) and 15 asymptomatic
(>80%) stenotic ICAs. The PAES was positioned in all
30 patients, although access for flow reversal was not
successful in 2 of them. One patient had onset of
aphasia after flow reversal, necessitating balloon defla-
tion between subsequent stages of the procedure.
There were no strokes or neurologic deficits at 30
days.
Bates et al.
33
reported on a series of 62 patients,
including 27 (44%) with restenotic lesions after remote
CEA and 11 (18%) who had previously undergone
radical neck surgery and external-beam radiation ther-
apy for cancer. There were no strokes or TIAs during
the CAS procedure or follow-up. Intolerance to ICA
flow arrest or reversal occurred in five patients, but the
procedures were completed in stages, without seque-
lae. Independent neurologic evaluations detected no
important changes in National Institutes of Health
Stroke Scale (NIHSS) status.
Rabe et al.
34
recently reported results of CAS using
reversal of flow in 56 patients. The procedure was
technically successful in all cases. There were no
strokes or deaths during the intervention. Fifty-five
of the 56 patients (98.2%) had a full recovery, with no
change in NIHSS status, immediately after deflation of
the occlusion balloons. One patient had a TIA and
became unconscious for 1 minute and aphasic for 3
minutes because of the strong suction required to
remove a thrombus at the lesion site. These symp-
toms resolved completely at the end of the proce-
dure, and post-procedure cerebral MR imaging (MRI)
showed no evidence of a new ischemic lesion or
bleeding. Cerebral MRI or CT scanning was performed
before CAS in 54 of the 56 patients (96.4%) in this
series. The imaging studies showed that 15 of the
patients (27.7%) had ipsilateral ischemic lesions and
13 (24.1%) had contralateral ischemic lesions. After
CAS, cerebral MRI or CT scanning was performed in
46 of the 56 patients (82.1%) and no new ipsilateral or
contralateral ischemic lesions were found.
Cerebral protection devices that provide proximal
occlusion with or without reversal of flow (PAES and
MO.MA [Invatec, Roncadelle, Italy]) activate protection
before interaction with the lesion and collect all
released particles. This represents an important advan-
tage over distal protection devices, since ex vivo stud-
ies found that 15% of the particles released during
CAS are related to crossing the lesion before protec-
tion can be initiated.
23
In addition, TCD studies per-
formed during CAS procedures showed HITS consis-
tent with embolization occurring during simple manip-
ulation of the guidewire across the lesion.
35
Both the MO.MA device and the PAES reverse the
flow in the ICA, but the PAES does it continuously,
whereas the MO.MA device does it intermittently and
at the end of the procedure. However, release of
microemboli can occur between aspirations,
36
so con-
tinuous flow reversal theoretically provides better
cerebral protection. Other disadvantages of the
MO.MA system are that it cannot be used when the
ECA is occluded; cerebral protection cannot be estab-
lished before interaction with the lesion when the
stenosis is in the CCA; and protection is not available
during removal of the MO.MA system (pulling down
of the ECA balloon) because the CCA balloon has
already been deflated. When the stent crosses the
ECA ostium, the balloon catheter is compressed
between the stent and arterial wall, which may result
in release of plaque particles.
36
Aside from providing continuous flow reversal, the
PAES has the advantage of being separate from the
working wire, thus allowing the interventionalist to
select a wire that is most appropriate for the patient’s
specific ICA anatomy. Moreover, even patients with a
contralateral occlusion or an incomplete circle of
Willis may be able to undergo CAS with either flow
reversal and intermittent cerebral protection or with
a PAES to facilitate placement of a distal filter (seat belt
and air bag technique).
37
The second-generation PAES, currently named the
NPS (Neuroprotection System), has been redesigned
by its new manufacturer (W.L. Gore & Associates,
Flagstaff, AZ, USA) to make it lower in profile, more
flexible, kink resistant, and easier to use. This new-
generation device received the CE Mark in July 2006
and is now in investigational use in the Embolic
Protection with Flow Reversal (EMPIRE) trial in the
United States. Our experience in 200 patients sug-
gests that ongoing and subsequent research will con-
firm that CAS using flow reversal is a safe and effec-
tive method for treating carotid artery stenosis.
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