carotid artery disease
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Carotid Artery DiseaseCarotid 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
True in about 70% Common variant: L CCA
originating from innominate artery
12 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.
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 (yellow-orange) is show, distinct from the normal lumen (red).
Carotid Duplex Ultrasound: Interpretation
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
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
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% Specificity 93.5% Stroke. 2008;39:2237-2248
MR Angiogram
LR
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
Stroke. 2005;36:27 Data from NASCET and ACAS
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
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