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Carotid Stenting and Transcranial Doppler Monitoring: Indications for Carotid
Stenosis Treatment
Article in Vascular and Endovascular Surgery · October 2010
DOI: 10.1177/1538574410375313 · Source: PubMed
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Carotid Stenting and Transcranial Doppler
Monitoring: Indications for Carotid Stenosis
Treatment
Vascular and Endovascular Surgery
44(7) 535-538
ª The Author(s) 2010
Reprints and permission:
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DOI: 10.1177/1538574410375313
http://ves.sagepub.com
Roberto Gattuso, MD1, Ombretta Martinelli, MD1,
Alessia Alunno, MD1, Ilaria D’Angeli, MD2, Marco Felli, MG, MD1,
Anna Castiglione, MD1, Luciano Izzo, MD, PhD1, and
Bruno Gossetti, MD, PhD1
Abstract
Background: Recently, angioplasty and stenting of carotid arteries (CAS) have taken the place of surgery. The aim of our study is to
assess the role of transcranial Doppler (TCD) monitoring during CAS to address the embolic complications during the stages of the
procedure, with or without embolic cerebral protection devices. Methods: A total of 152 patients were submitted to carotid
stenting. All patients were submitted to carotid arteries Duplex scanning. Results: Neurological complications are related to
TCD detection of corpuscolate signals in rapid succession. Even if no reduction of the overall incidence rate of microembolic
signals (MES) was observed, a decrease in the number of corpuscolate emboli were recorded when a cerebral protection was
working. Conclusions: According to our study, even in selected patients on the basis of preoperative diagnostic criteria, CAS
is burdened by a nonnegligible risk of subclinical embolic ischemic events detected at TCD and confirmed by diffusion-weighted
magnetic resonance imaging (DW-MRI).
Keywords
angiography, carotid artery, stenting, transcranial doppler, imaging
Introduction
A large body of evidence is now available on evaluation and
management of patients with cerebrovascular disease. Two
prospective randomized trials, 1 in North America (NASCET)1
and 1 in Europe (ECST),2 have demonstrated the safety and
efficacy of carotid endarterectomy (CEA) over medical therapies for symptomatic patients with high-grade carotid stenosis.
More recent data from several studies established the role of
CEA for patients with unstable and or ulcerative plaques associated with less than 70% stenosis of carotid arteries, either
symptomatic or asymptomatic.3,4 In the last years, carotid
angioplasty and stenting (CAS) has gained enough enthusiastic
support to be proposed as an alternative to conventional carotid
endarterectomy.5-7
The results of CAS are highly variable and mainly depend on
the risk of embolic events owing to catheters and wires use, angioplasty, and stent deployment across the lesion. The development
of emboli protection devices by temporary carotid arteries occlusion or by placing a filter distal to the lesion has been the second
major technical step designed to reduce the rate and severity of
embolic complications during CAS.8-10 On the ground of our
20-years experience with transcranial Doppler (TCD) during
CEA to monitor carotid cross clamping, the efficacy of indwelling
shunt, and to detect microembolic signals (MES),11-13 we have
been assessing the role of TCD monitoring during CAS to address
the embolic complications during the different stages of the procedure with or without embolic cerebral protection devices.
Materials and Methods
From January 2005 to December 2008, 152 patients, mean age
69 years, were submitted to carotid stenting. In all 112 (73.8%)
patients were asymptomatic and 40 (26.2%) symptomatic; in
this last group were included only patients who had neurologic
symptoms coherent to carotid lesion more than 6 months
before. In 127 (83.6%) cases, the carotid lesions were primitive
and in the remaining 25 (16.4%), a restenosis after CEA was
present.
Preoperatively, all patients were submitted to carotid
arteries Duplex scanning.14,15 All patients had >70% carotid
1
Department of Vascular Surgery A, ‘‘Sapienza’’ University, Rome, Italy
Department of Heart and Great Vessels ‘‘A. Reale,’’ ‘‘Sapienza’’ University,
Rome, Italy
2
Corresponding Author:
Ilaria D’Angeli, Sapienza University of Rome, Viale del Policlinico, 155, 00166,
Rome, Italy
Email: ilaria.d@libero.it
535
536
stenosis as determined using duplex criteria validated in our
unit including internal carotid artery (ICA) peak systolic velocity (PSV) >180 cm/s and end-diastolic (EDV) velocity >80
cm/s. A subgroup with 80% to 90% were also identified (PSV
ICA > 250 cm/s; EDV ICA > 100 cm/s). Ultrasound B-mode
imaging of each carotid artery plaque was performed using a
high-resolution scanner (Toshiba Aplio) and a 5-MHz to 7MHz multifrequency linear array probe. Images were normalized using 2 reference points (blood and adventitia) to a set
gray scale from 0 (black) to 255 (white). Plaque composition
was then determined using the criteria suggested by the
European Carotid Plaque Study Group.16 According to those
criteria, all the carotid artery lesions submitted to CAS were
iperechoic, predominantly fibrous with low calcifications and
smooth profile. A computed tomography scanning or a magnetic resonance angiography was always carried out to assess
aortic arch and cerebral vessels anatomy.
All patients underwent a detailed neurologic examination
and cognitive tests (CSF-12 questionary, Mini-mental state,
Beck depression inventory, and Zung anxiety inventory) before
treatment and at 1, 3, and 6 months, postoperatively.
A preoperative Transcranial Doppler (TCD; DWL Multidop) 60/min-monitoring was carried out in all cases to evaluate
the Willis circle and the vasomotor reactivity by means of functional tests and to detect cerebral embolic events. All patients
with MES recorded in the preoperative monitoring were
excluded from this study. Microemboli were recorded by TCD
as high-intensity signals (MES) and were characterized in
terms of direction, duration, and amplitude to identify the corpuscolate emboli and the bubbles. Both middle cerebral arteries
TCD monitoring was always performed throughout CAS from
the percutaneous approach to 60’ after the end of the procedure.
Diffusion-weighted magnetic resonance imaging (DW MRI)
was always performed before discharge, typically on first or
second postoperative day. The MRI studies were examined
by blinded investigators to determine the presence of acute
changes and the number of lesions.
Extracranial and intracranial angiography was carried out at
the time of intervention to confirm preoperative imaging. The
CAS technique involved stent placement and postdilation in all
cases.
In 2 cases, the procedure was stopped for an ongoing
reversible upper monoparesis and disphasia after guiding
catheter positioning in common carotid artery (CCA) and consequently before cerebral protection device insertion. In the
remaining cases, a carotid Wallstent was implanted in 119
(79.6%) patients, a Precise in 19 (12.8%), an Acculink in 8
(5.3%), and a Protegè in 4 patients (2.8%).
The cerebral protection devices were an Epifilter Wire EZ in
110 patients (73.3%), an Angioguard in 19 (12.7%), an Accunet in 8 (5.3%), and a SpiderX in the last 13 patients (8.7%).
Results
There was no perioperative death or intraoperative major
stroke. During the follow-up (3-6 months), it has not been
536
Vascular and Endovascular Surgery 44(7)
possible to correlate any death or major stroke to the procedure;
2 patients died of miocardial infarction.
In 2 cases, the procedure was stopped before stenting
because of an ipsilateral transient ischemic attack (TIA) that
occurred during catheterization of the CCA and 1 contralateral
TIA that occurred when the guiding catheter was withdrawn
from the aortic arch. Intraoperatively, 5 patients suffered from
minor stroke that was reversible in few hours during the ICU
recovery. One patient developed a postoperative atassic syndrome for stent dislodgement in the CCA; this major stroke
occurred on the second postoperative day. In summary, we collected 8 complications out of 152 procedures, with a 5.2% incidence rate. Nevertheless, only 1 patient remained symptomatic
with an atassic syndrome, while the remaining 7 became
symptom-free few days after the procedure. During CCA cannulation, filter positioning and withdrawal, MES incidence rate
were 81%; conversely, during percutaneous angioplasty (PTA),
stenting and post-ballooning, the incidence rate of MES was
31%. In the 6 patients who developed neurological deficit,
symptoms followed a rapid sequence of corpuscolate MES
(>8/min) by TCD; in 5 cases, those MES were recorded on
stent realising and subsequent ballooning.
We found mono or bilateral new ischemic hemispheric
lesions at 24 to 48 hours by DW-MRI in 66 (44%) of 152
patients. It must be underlined that TIAs and minor or major
strokes developed only in 12.1% (8 of 66) of those patients.
As far as the remaining asymptomatic patients with positive
DW-MRI, the cognitive tests showed a decline in neuropsychometric permormance in 66.6% (36 of 54), with a 24% overall
incidence rate and with a more evident cognitive impairment
in younger.
The symptomatic patients suffering from minor or major
strokes had DWI lesions larger than 20 mm2. There were
no differences in terms of size and hyperintensity on
postoperative DWI in the cases with TIA as compared to the
asymptomatic ones.
Discussion
In the last years, angioplasty and stenting of carotid arteries
have been introduced to take the place of surgery in this field.
Based on the large experience obtained by intraoperative TCD
monitoring of middle carotid artery (MCA) during CEA (more
than 900 procedures were monitored in the last years, under
general and locoregional anesthesia), we decided to apply this
technique in patients submitted to endovascular procedures.
Transcranial Doppler monitoring was used before and during
the treatment to achieve different purposes. Preoperatively, the
measure of decrease of middle blood velocity (MBV) in MCA
during temporary digital compression test of ipsilateral CCA
allows to evaluate the effectiveness of intracranial circulation
and whether the occlusion of vessel by balloon is feasible and
without complications. Microembolic signal monitoring shows
the risk of embolism due to plaque surface and morphology.
Pretreatment study of morphological pattern of plaque by
color-duplex imaging and of embolic risk by TCD may reduce
Roberto et al
Figure 1. Position of the TCD with bilateral MCA insonorization
duing the carotid stenting.
the incidence of embolic complications during endovascular
procedures. Intraoperatively, using TCD monitoring, the
changes of cerebral perfusion due to the presence of cerebral
protection devices (filters) are the indicators of the effectiveness
and efficacy of the devices itself in reducing MES throughout
the procedure (Figure 1). Moreover, the identification of MES
during angioplasty, stenting, and ballooning might allow to
modify the procedure and to avoid neurological deficit.
The simultaneous online monitoring of both middle cerebral
arteries have shown also a very important finding characterized
by a relevant number of MES recorded on the contralateral
hemisphere during the catheter passage across the aortic arch.
This emphasized the opinion that the presence of atherosclerotic plaque is the cause of those microembolic events that we
have collected in the contralateral side and that were also evident as ischemic lesions at the MR with DWI images. On this
basis, we have changed the procedural approach to the cerebral
vessels, avoiding always the aortic arch angiography, excluding those patients with grade IV and grade V plaques of the
aortic arch visualized on angio TC or transesophageal echocardiography and choosing alternative approach for the carotid
vessels like axillary way or low surgical cervicotomy.
In our experience, the TCD has clearly confirmed that the
routine use of the cerebral protection devices is recommended
during carotid stenting. These data were obtained from the
observations that the larger number of MES were recorded
mainly within the 2 most important stages of the procedure,
which are stent deployment and ballooning.
Nevertheless, in our experience, we have found a positive
DW-MRI in 66 (44%) of 152 patients, which experienced neurological deficits only in 5.2% of cases while the remaining
patients were asymptomatic. The correlation between clinical
537
Figure 2. Magnetic resonance imaging (MRI) in diffusion-weighted
imaging (DWI): bilateral cerebral ischemic lesions 24 hours after
procedure.
symptoms and procedure timing showed clearly that in all
5 symptomatic patients, the TCD have recorded a rapid
sequence of corpuscolate MES just during stent release and
ballooning. This suggests that, if it is true that the cerebral
protection device are able to reduce the number of MES
(31% versus 81%), this does not imply that there is a complete
protection from microembolism.
DTC microembolic signals, recorded throughout the
carotid-stenting procedure are asymptomatic in most of the
cases and this raised a question about the clinical relevance
of those findings in the past. This experience has demonstrated
that asymptomatic MES detection during percutaneous carotid
intervention may be related to onset of new ischemic lesions at
postoperative DW-MRI. Our results are consistent with the
recent studies by Zhou et al15 and Palombo et al.17
Nevertheless, these encouraging results collected, the new
data we obtained with the routine pre and postoperative use
of the cognitive tests and DW-MRI, are showing new controversial findings.18 The presence of ischemic cerebral lesions
in both cerebral and cerebellar hemispheres in symptomatic
(Figure 2) and asymptomatic patients and a worsening cognitive test in about 36% of them represent a new ongoing scenario.19, 20 On the basis of these results, we believe that new
prospective studies are needed to confirm our findings.
The endovascular treatment of stenotic lesions is fascinating
and elegant, but the question is if this is the best treatment for
the brain.
Nevertheless, according to our study, even in selected
patients on the basis of preoperative diagnostic criteria,
CAS is burdened by a nonnegligible risk of subclinical
537
538
embolic ischemic events detected at DTC and confirmed by
DW-MRI. These events correlate with the potential cognitive
impairment of these patients. These findings suggest the need
for a greater selection of patients from each side of further
studies to confirm.
Declaration of Conflicting Interests
The author(s) declared no conflicts of interest with respect to the
authorship and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for
the research and/or authorship of this article: Research Council of
Mashhad University of Medical Sciences.
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