Carotid Artery Disease
Lenore C. Ocava, MD
Vascular Neurology
AECOM/Jacobi Medical Center
Anatomy: Transverse Aortic Arch
 Brachiocephalic trunk or
Innominate Artery (1)
 R common carotid artery
 R subclavian artery
 Vertebral artery
 Left common carotid Artery (2)
 Left subclavian artery(3)
 L vertebral artery
1
2
3
 True in about 70%
 Common variant: L CCA
originating from innominate artery
Anatomy: Common Carotid Artery
 Located anterolaterally in the neck
and medial to the jugular vein
 The carotid artery, jugular vein,
and vagus nerve are enclosed in
connective tissue - carotid sheath
 Terminates as the carotid
bifurcation  Internal carotid
artery (ICA) and External carotid
artery (ECA)
 At the vicinity of the superior
border of the thyroid cartilage or
approximately at the level of C4
 Bifurcation has been described to
be as low as T2 and as high as
C1.
External Carotid Artery
 smaller of the two terminal
branches of the CCA
 Has 8 branches : the superior
thyroid, ascending pharyngeal,
lingual, facial, occipital,
posterior auricular, and the
terminal branches, the
superficial temporal, and the
internal maxillary artery.
 The abundant number of
anatomoses between the
branches of the ECA and the
intracranial circulation 
provides important collateral
pathway for cerebral perfusion
when significant disease is
present in the ICA
Internal Carotid Artery
 The larger of the CCA terminal
branches
 Divided into 4 main segments:
Cervical
 begins at the CCA
bifurcation and extends to
the base of the skull
 normally has a slight
dilation, termed the carotid
bulb and/or the carotid
sinus
 usually does not have
branches
Petrous - inside the petrous
part of the temporal bone
Internal Carotid Artery
Cavernous
 invested within the
cavernous sinus
 situated between the
layers of the dura mater
of the cavernous sinus,
but covered by the
lining membrane of the
sinus
Cerebral – begins after
the artery perforates the
dura matter, passes
between the optic and
oculomotor nerves,
then proceeds to the
terminal bifurcation into
The Circle of Willis
 Formed by branches from
paired carotid (anterior
circulation) and vertebral
(posterior circulation)
arteries
 the posterior cerebral,
posterior communicating,
internal carotid, anterior
cerebral, and anterior
communicating arteries
on each side
 Allows for “collateral flow”
in the setting of
atherostenosis or
occlusive disease
Carotid Artery Disease
 Vascular layers: adventitia, intima,
media
 Carotid disease is mostly due to
atherosclerosis  buildup of




cholesterol and fibrotic tissue in
the arterial wall
results from both genetic and
environmental influences
Caucasians – cervical carotid
disease
Ethnic minorities – intracranial
atherostenosis
Other uncommon causes:
dissection, vasculitis,
fibromuscular dysplasia
Evaluation of Patients with Carotid
Disease - History
Useful information:
vascular risk factors
focal neurologic deficits
transient monocular blindness
Likely unrelated events
Syncope
headache or pain*
*except in dissection
Evaluation of Patients with Carotid
Disease – Carotid Artery Bruit
Classic recommendation: assess for the
presence of a bruit (CAB – carotid artery
bruit)
Questions:
Does a detectable CAB indicate the presence
of a significant lesion?
Does the absence of a CAB preclude the
presence of a significant lesion?
Will the presence of a CAB change further
investigation and disposition?
Evaluation of Patients with Carotid
Disease – Carotid Artery Bruit
 Hemodynamically significant stenotic lesions
may exist in the absence of an audible bruit.
 The absence of CAB may also signify complete
occlusion of the carotid artery.
 CAB assessment has a sensitivity of 63%-76%
and specificity of 61%-76% for clinically
significant stenosis*
 Irrespective of the detection of a CAB in patients
with possible vascular events, most authorities
would still recommend imaging studies.
* Using 70%-99% stenosis on a carotid angiogram as a gold standard threshold
Evaluation of Patients with Carotid
Disease – Imaging Studies
 Available Options
 Carotid duplex US
 Non invasive, virtually
without complications
 Readily available and
quick to do
 Sensitivity ~70% when
compared with
angiography
 CT angiogram – CT with IV
contrast, very thin sections
 Good resolution but
requires expertise for
interpretation
 Readily available and
quick to do
 Complications associated
with IV dye
 MR angiogram
 Good resolution but requires
expertise for interpretation
 Readily available (except in
Jacobi) and relatively quick to
do
 Claustrophobia-inducing
machine  patient required to
lie still for about 20-30 minutes
 Digital subtraction angiography
 gold standard
 Invasive
 Complications related to IV
dye
 1% stroke risk associated with
the procedure
Carotid Duplex Ultrasound
 The degree of
stenosis is
determined by the
velocity of blood flow
through the artery
 the higher the
velocity, the greater
the degree of stenosis
Carotid Duplex Ultrasound
 Color doppler can
demonstrate the area of
stenosis with increased
flow ( blue/ yellow flow
pattern in this image)
 B-mode can demonstrate
the walls of the vessel and
the area of stenosis
Carotid Duplex Ultrasound
 Can identify other
pathology.
 Carotid artery
dissection - the "false“
channel (yelloworange) is show,
distinct from the
normal lumen (red).
Carotid Duplex Ultrasound: Interpretation
Carotid Duplex Ultrasound: Interpretation
>70% stenosis
 with contralateral
PSV < 125 cm/sec
ICA occlusion: ICA
flow velocity may be
PSV>125 cm/sec
falsely elevated
EDV>140 cm/sec
 Other important
information:
ICA/CCA (PSV) >4
Occlusion
Absence of flow
<50% stenosis
50-79% stenosis
80-99% stenosis
 extent of the plaque
 plaque
characteristics
 patency of the distal
ICA
CT Angioram
 Using a 70% cutoff value
for stenosis, CTA
compared to DSA
 agreement in 96% of
cases
 sensitivity 100%
 specificity 63%
 negative predictive value
was 100%
 Interobserver agreement
was higher for CTAmeasured stenosis than
for DSA-measured
stenosis
Neurology. 2004;63:412-413, 457-460
CT Angioram
MR Angiogram
 70% to 99% ICA stenoses
 Time-of-flight MRA
Sensitivity 91.2% Specificity 88.3%
 Contrast-enhanced MRA
Sensitivity 94.6%
Specificity 91.9%
 ICA occlusion
 Time-of-flight MRA
Sensitivity 94.5% Specificity 99.3%
 Contrast-enhanced MRA
Sensitivity 99.4%
Specificity 99.6%
 Moderate (50 to 69%) stenoses
 Time-of-flight MRA
Sensitivity 37.9%
Specificity 92.1%
 Contrast-enhanced MRA
Sensitivity 65.9%
Stroke. 2008;39:2237-2248
Specificity 93.5%
MR Angiogram
R
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Digital Subtraction Angiogram
Treatment Strategy #1
stabilize or halt the progression of the carotid plaque
Risk Factor
Target
Comment
Hypertension
SBP <140 and DBP <90.
For patients with diabetes, SBP<130 and
DBP <85
Use of ACEIs should be
encouraged
Diabetes
FBS < 126 mg/dL
Diet and oral hypoglycemic
agents or insulin as needed
Elevated lipid levels
LDL <100 mg/dL
AHA step II diet (<30% fat,
<7% saturated fat, < 200mg
chol/d)
Statin therapy if lipid levels
remain elevated
Cigarette smoking
Stop smoking
Counseling, specific therapies
Alcohol use
Eliminate excessive use
Mild to moderate use (1-2
drinks per day)
Physical activity
30-60 minutes of exercise at least 3x per
week
Treatment Strategy #2
eliminate or reduce carotid stenosis
Treatment Strategy #2
eliminate or reduce carotid stenosis
 Carotid endarterectomy (CEA) – treatment of
choice
 Other procedures
EC-IC bypass: not beneficial (1980’s)
Currently being revisited - Carotid Occlusion Surgery
Study (COSS)
• aims to identify a subgroup of patients with carotid occlusion
that may benefit from EC-IC bypass
• ipsilateral increased oxygen extraction fraction (OEF)
measured by positron emission tomography (PET)
Carotid angioplasty and stenting
trials and case series have shown that the outcomes of
stenting are worse than or no different from those of
carotid endarterectomy
Current use limited to patients with high surgical risk
preventing the performance of CEA
Symptomatic Carotid Stenosis
>70% stenosis
2 rate of ipsilateral stroke: 26% in the medical
group and 9%in the surgical group*
Relative risk reduction 65%*
Absolute risk reduction 17%*
NNT 7-8 (# patients who would need to
undergo endarterectomy to prevent one stroke
in a 5-year period)**
*,**North American Symptomatic Carotid Endarterectomy Trial (NASCET), the **European
Carotid Surgery Trial (ECST), and the trial by the Veterans Affairs Cooperative Studies
Program
Symptomatic Carotid Stenosis
<50% stenosis
trials showed that there was no significant
benefit of surgery.
in NASCET, there was no significant difference
in the risk of ipsilateral stroke between those
who were treated with endarterectomy and
those who were treated medically
North American Symptomatic Carotid Endarterectomy Trial (NASCET), the European Carotid
Surgery Trial (ECST), and the trial by the Veterans Affairs Cooperative Studies Program
Symptomatic Carotid Stenosis
Moderate stenosis, 50 to 69%
In ECST, there was no significant benefit of
surgery for those with moderate stenosis.
In NASCET, the 5-year risk of fatal or nonfatal
ipsilateral stroke among patients was 22.2% in
the medical group and 15.7% in the surgical
group
Absolute risk reduction 6.5%
NNT 15
North American Symptomatic Carotid Endarterectomy Trial (NASCET), and the European
Carotid Surgery Trial (ECST)
Patients with symptomatic moderate
grade stenosis with greatest benefit from
CEA
more severe stenosis
75 years of age and older
men
patients with a recent (within 3 months) history of stroke
(rather than transient ischemic attacks) as the qualifying
event
patients with hemispheric TIAs rather than transient
monocular blindness
radiographic factors: the presence of intracranial
stenosis, the absence of microvascular ischemia, and
the presence of collateral vessels
operative risk
experience of the surgeon
Asymptomatic Carotid Stenosis
 the risk of stroke is lower than that associated
with symptomatic disease
 In observational studies, the rate of ipsilateral
stroke was 1 to 3% per year among patients with
asymptomatic stenosis of greater than 50%
 the risk in NASCET was 3.2% per year for
asymptomatic stenosis of 60 to 99%
Asymptomatic Carotid Atherosclerosis
Study (ACAS) - >60% stenosis
 The risk of ipsilateral stroke or any perioperative stroke
or death was 5% during 5 years of follow-up in surgically
treated patients and 11% in medically treated patients.
 Absolute risk reduction (ARR) 6%
 NNT 17
 Because of the lower ARR, a rate of perioperative
complications (stroke or death) of more than 3% would
eliminate the potential benefit of the operation
 The benefit of surgery was greater for men than
women (reduction in risk, 66% vs. 17%)
 The rate of perioperative complications was higher
among women than men (3.6% vs. 1.7%).
Risk and Benefit of CE in Women With
Symptomatic Carotid Artery Disease
 With 70% stenosis, the 5-year absolute risk
reduction (ARR) in stroke from CE was similar
between women (15.1%) and men (17.3%).
30-day perioperative risk of death was higher in women
than in men (2.3% versus 0.8%)
Higher perioperative risk of stroke and death was also
observed in women (7.6% versus 5.9%) but not
statistically significant.
 With 50% to 69% stenosis
CE was not beneficial in women (ARR=3.0%), contrary
to men (ARR=10.0%).
Medically treated women had low risk for stroke
Data from NASCET and ACAS
Stroke. 2005;36:27
Challenging the Results From ACAS and
NASCET
 Observational study
 Results
(Southern Illinois University School of
Medicine )
 Surgical death rates were
nearly identical for
 21-year period
asymptomatic and
 1,204 CEAs performed
symptomatic patients.
 464 (39%) in
 Perioperative stroke rates
women
were similar for
 739 (61%) in men
asymptomatic and
symptomatic patients.
 Complete follow-up
was available in 70% of
 Life-table stroke-free rates
patients.
at 1, 5, and 8 years were
similar for asymptomatic
women and men and
stroke-free survival rates at these follow-up
symptomatic women and
intervals were greater for asymptomatic
men.
women compared with men, and for
symptomatic women compared to men
Ann Surg. 2001 October; 234(4): 438–446
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