2. 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
True in about 70%
Common variant: L CCA
originating from innominate artery
1
2 3
3. 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.
4. 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
5. 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
6. 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
7. 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
8. 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
9. 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
10. 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?
11. 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
12. 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
13. 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
14. 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
15. Carotid Duplex Ultrasound
Can identify other
pathology.
Carotid artery
dissection - the "false“
channel (yellow-
orange) is show,
distinct from the
normal lumen (red).
17. Carotid Duplex Ultrasound: Interpretation
<50% stenosis PSV < 125 cm/sec
50-79% stenosis PSV>125 cm/sec
80-99% stenosis EDV>140 cm/sec
>70% stenosis ICA/CCA (PSV) >4
Occlusion Absence of flow
with contralateral
ICA occlusion: ICA
flow velocity may be
falsely elevated
Other important
information:
extent of the plaque
plaque
characteristics
patency of the distal
ICA
18. 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 CTA-
measured stenosis than
for DSA-measured
stenosis
Neurology. 2004;63:412-413, 457-460
23. 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
25. 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
26. 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
27. 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
28. 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)
29. 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
30. 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%
31. 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%).
32.
33. 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
Stroke. 2005;36:27Data from NASCET and ACAS
34. Challenging the Results From ACAS and
NASCET
Observational study
(Southern Illinois University School of
Medicine )
21-year period
1,204 CEAs performed
464 (39%) in
women
739 (61%) in men
Complete follow-up
was available in 70% of
patients.
Results
Surgical death rates were
nearly identical for
asymptomatic and
symptomatic patients.
Perioperative stroke rates
were similar for
asymptomatic and
symptomatic patients.
Life-table stroke-free rates
at 1, 5, and 8 years were
similar for asymptomatic
women and men and
symptomatic women and
men.
Ann Surg. 2001 October; 234(4): 438–446
stroke-free survival rates at these follow-up
intervals were greater for asymptomatic
women compared with men, and for
symptomatic women compared to men