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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3892_Библиотеки_им_академика_М_И_Перельмана
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250
What are some pros and
cons of using MRA for
evaluation of carotid
artery stenosis?
Pros
Anatomic imaging of the aortic arch
and major branch vessels
Allows for evaluation of both
intrathoracic and intracranial
vasculatures, unlike US
No ionizing radiation
Best noninvasive method for
evaluating heavily calcified lesions
Overall best for assessing plaque
morphology including ulceration
and risk of thromboembolic event
Lower risk of adverse
events (including allergy and
nephrotoxicity) from gadolinium-
based contrast agents used in MRA
than from iodinated contrast agents
used in CTA
Cons
Can overestimate stenosis
Cannot reliably discriminate
subtotal vs complete occlusion
Use limited in patients with:
Claustrophobia
Extreme obesity
Certain incompatible implanted
devices
Depending on type and amount
of gadolinium agent used and
possible risk of nephrogenic
systemic fibrosis (NSF) in some
patients with renal dysfunction:
Alternatively, time-of-flight MRA
technique may be used to evaluate
the vessels without the use of
contrast.
What is a limitation of
MRA in the evaluation
of carotid stenosis?
Accurate quantification of the degree
of endoluminal stenosis due to motion
artifact and flow voids
G. Gadodia
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251
What are some pros and
cons of using CTA for
evaluation of carotid
artery stenosis?
Pros
Anatomic imaging of the aortic arch
and major branch vessels:
Allows for evaluation of both
intrathoracic and intracranial
vasculatures, unlike US
Best noninvasive evaluation of
the arterial lumen and degree of
stenosis
No limitations based on
implanted devices
Often used in cases with
equivocal findings on US and
MRA, or with issues excluding
MRA evaluation
Cons
Ionizing radiation
Use of iodinated contrast:
Higher risk of adverse event
including allergy and nephrotoxicity
than Gd-based agents used in
MRA:
Limits use to patients without
renal dysfunction
Poor evaluation of heavily
calcified lesions due to artifact
Cannot reliably discriminate
subtotal vs complete occlusion
Overlying metal including
implanted devices and surgical clips
may obscure evaluation due to
artifact.
(continued)
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252
What is the gold standard
for evaluation of
carotid and intracranial
atherosclerosis, and why?
Digital subtraction angiography
(DSA) of aortic arch, bilateral
carotids, and bilateral vertebral
arteries including distal to the stenosis
Can assess for:
Degree of stenosis:
Most sensitive method, including
in evaluating possibly complete
occlusion
Intrathoracic and intracerebral
disease
Aberrant anatomy
When is DSA indicated
over noninvasive imaging
(US, CTA, or MRA)?
When noninvasive testing is
inconclusive or not feasible because of
technical issues or contraindications
in patients with transient retinal/
hemispheric neurological symptoms of
suspected ischemic origin (IIa, C)
For evaluation of the possibility of
revascularization when noninvasive
testing suggests complete carotid
occlusion (IIb, C)
Of note: While it is the gold standard
for diagnosis, DSA is generally only
done during planned endovascular
therapeutic intervention.
What past medical
history is especially
important to know pre-
procedurally?
History of radiation to the neck
History of coronary artery disease
(e.g., angina, stents, MIs, CABG)
G. Gadodia
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High Yield History
What are potential
underlying causes of carotid
stenosis?
Atherosclerotic plaque (most
common)
Aneurysm
Arteritis
Carotid dissection
Mass/neoplasm (both benign such
as glomus tumor and malignant
soft tissue tumors)
Radiation necrosis/intimal
hyperplasia
Vasospasm
Cystic medial necrosis
Fibromuscular dysplasia (FMD)
What are risk factors for
carotid stenosis?
Genetic (family history)
Hypertension (HTN)
Diabetes mellitus (DM)
Smoking
Hypercholesterolemia
What percentage of ischemic
strokes are caused by
extracranial ICA disease?
20–30%
What is the mechanism of
ischemic stroke from ICA
disease?
Embolization of atherosclerotic
debris or thrombotic material
from plaque into more distal
cerebral vessels
How is carotid stenosis
graded (according to 2011
ASA/ACC guidelines)?
Moderate: 50–69%
Severe: 70–99%
(continued)
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What velocities on ultrasound
correspond to what level of
stenosis?
Moderate stenosis (50–69%):
PSV of 125–230cm/s
Ratio of ICA to CCA PSV of
2–4
End-diastolic velocity (EDV) of
40–100cm/s
Severe stenosis (>70%):
PSV>230cm/s
Ratio of ICA to CCA PSV of
>4
EDV>100cm/s
What is the gold-standard
treatment for patients
with asymptomatic carotid
stenosis from atherosclerosis?
Antiplatelet therapy with aspirin,
75–325mg daily (I, A):
If patient has HTN: add
antihypertensives to maintain BP
below 140/90 (I, A).
What is the gold-standard
treatment for patients with
symptomatic carotid stenosis
from atherosclerosis (overall
class I, LOE B)?
Aspirin 75–325mg daily alone
Clopidogrel 75mg daily alone
Aspirin plus extended-release
dipyridamole (25 and 200mg
BID, respectively):
Better than aspirin and
clopidogrel together, which shows
no benefit within 3months of
symptoms
Is there a role for
anticoagulation in the setting
of carotid artery stenosis?
Anticoagulation with
unfractionated or LMW
heparin is not recommended in
symptomatic patients with carotid
stenosis (III, B):
Antiplatelet agents are
recommended over oral
anticoagulants in patients with
stenosis with (I, B) or without (I,
C) ischemic symptoms.
G. Gadodia
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How should patients with an
allergy to aspirin be treated
(IIa, C)?
Using P2Y
12
inhibitors on their
own, including:
Clopidogrel
Prasugrel
Ticagrelor
Cangrelor
What are the major
methods of carotid artery
revascularization?
Surgical carotid endarterectomy
(CEA)
Endovascular carotid artery
stenting (CAS)
Indications/Contraindications
What are the
indications for
revascularization in
symptomatic carotid
artery stenosis?
Symptomatic patients at low or average
risk of procedural complication (<6%
risk of major complication or mortality)
should undergo CEA or CAS for
revascularization if the lumen of the
ipsilateral carotid artery is reduced by
>70% by noninvasive imaging or >50%
by angiography (class: I).
When should
intervention be
undertaken in relation
to symptoms?
In cases where revascularization is
indicated in symptomatic patients
without contraindications, reasonable to
do so within 2weeks of symptom onset
(IIa, B)
(continued)
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What are the
indications for
revascularization in
asymptomatic carotid
artery stenosis?
Asymptomatic patients should
undergo revascularization based on
an assessment of comorbidities, life
expectancy, and other individual factors
(I, C):
Reasonable to do CEA in
asymptomatic patients with >70%
stenosis of the ICA and with low risk of
perioperative stroke, MI, or death (IIa,
A).
CAS may be considered in highly
selected patients with asymptomatic
carotid stenosis (minimum 60% by
angiography, 70% by validated Doppler
ultrasound) (IIb, B).
Of note: There is no data to prove
that this is really better than medical
therapy alone.
Overall, what
is the current
recommendations
regarding treatment
choice in carotid
revascularization?
If there are no contraindications, CEA
is generally recommended over CAS:
Symptomatic patients
50–69% stenosis:
CEA (I, B)
CAS (I, B)
70–99% stenosis:
CEA (I, A)
CAS (I, B)
Asymptomatic patients
70–99% stenosis:
CEA (IIa, A)
CAS (IIb, B)
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When should CAS be
chosen over CEA for
revascularization?
When neck or lesion anatomy is
unfavorable for arterial surgery (IIa, B),
including:
History of prior neck surgery or
radiation therapy to the neck
Carotid dissection
Tandem stenosis (carotid and
ipsilateral intracranial stenosis)
Surgically inaccessible lesion
(intrathoracic or intracranial)
Tumor encasing the carotid artery
Existing tracheostomy
Limitation in cross flow circulation:
Contralateral carotid occlusion
or other disease requiring
revascularization
Stenosis after completed or
attempted CEA within past 31days
In patients with significant cardiac
history and risk of periprocedural
cardiac event (controversial), including:
Congestive heart failure
LVEF < 30%
Recent MI
Significant coronary artery disease
Unstable angina
Uncontrolled diabetes
Recent heart surgery (<6weeks)
In what situations is
revascularization not
recommended?
<50% atherosclerotic luminal
narrowing (III, A)
Chronic total occlusion of the target
artery (III, C)
In patients with severe disability caused
by cerebral infarction that precludes
preservation of useful function (III, C)
(continued)
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What are absolute
contraindications to
CAS?
Chronic carotid artery occlusion
Allergy to antiplatelet medications
Allergy to metals in stent
Uncorrectable coagulopathy
Incompatible anatomy
What are relative
contraindications to
CAS?
Acute clot within stenosis
History of stroke within 6weeks or
prior disabling stroke (modified Rankin
scale >3)
Recent intracranial hemorrhage
Bacteremia/sepsis
Immunocompromised state
Circumferential or near circumferential
calcified lesion
What are the
indications for
re-intervening in
patients with restenosis
after revascularization?
Reasonable to repeat CEA or perform
CAS in patients with symptomatic
cerebral ischemia (symptomatic
patients) and recurrent carotid
stenosis due to intimal hyperplasia
or atherosclerosis, using the same
criteria as recommended for initial
revascularization (IIa, C).
Reasonable when duplex ultrasound
AND another confirmatory imaging
method identify rapidly progressive
restenosis that indicates a threat of
complete occlusion (IIa, C).
In asymptomatic patients with recurrent
stenosis, re-operative CEA or CAS
may be considered using the same
criteria as recommended for initial
revascularization (IIb, C),
What is a
contraindication to
reoperation?
Asymptomatic patients with <70%
stenosis (class III)
G. Gadodia
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Relevant Anatomy
What three major branches
commonly arise from the
aortic arch?
Brachiocephalic trunk (innominate
artery), left common carotid artery,
and left subclavian artery
What is the most common
aortic arch anatomic
variant?
Common origin of the
brachiocephalic and left common
carotid arteries (often colloquially
called a “bovine arch,” which is a
misnomer, as it does not normally
occur in bovines)
Where do atherosclerotic
lesions usually occur in the
carotid?
At the external/internal carotid
bifurcation
Where do the external and
internal carotid arteries
usually bifurcate?
At the level of the thyroid cartilage
What is the carotid bulb? Dilated portion at the origin of the
ICA extending for about 2cm
What arteries provide
collateral circulation to
territories possibly affected
by a stenotic ICA?
Ipsilateral external carotid artery
Ipsilateral vertebral artery,
contralateral ECA, and vertebral
artery (via the circle of Willis)
What arteries should be
evaluated angiographically
prior to endovascular
revascularization?
Bilateral common carotids and
branches (external and internal
carotids)
Bilateral vertebral arteries
Relevant Materials
What kinds of catheter
can be used for carotid
angiography?
4 or 5 Fr diagnostic catheter
(e.g., Bernstein II, Sidewinder II,
Multipurpose, Vertebral, Headhunter)
(continued)
25 Carotid Artery Stenosis
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