A 2nd Look at Carotid Disease and Stroke:
Review and Evidence-based Practice Guidelines
* referenced with literature citations
1. Epidemiology of Stroke
a. Industrialized countries: 3rd leading cause of death (heart disease, cancer)*
b. #1 cause of disability for survivors*
c. Stroke Study: 700K annual US strokes, 500K new, 200K recurrent*
d. Racial disparities: Black>Hispanics>Caucasians*
e. Undetected ischemic cerebral events increase with age*
f. Ischemic-clot/hemorrhagic stroke ≈ 88%/12%*
g. Carotid & vertebral disease as cause of ischemic stroke: 5-17/100K population*
2. Extra- and Intra-cerebral circulation – anatomic wonder
a. Know our anatomy!
b. Steady, biphasic cerebral blood flow (vs. triphasic)
c. Patent collateralization beneficial when stenosis develops
i. External (EC) to internal carotid (IC) artery
1. Internal maxillary of ECsuperficial temporal supratrochlear &
supraorbital of IC
2. Occipital branch of EC ipsilateral vertebral
ii. Vertebrobasilar posterior communicating middle cerebral (IC)
iii. Intracranial (circle of Willis) ipsil.contral. IC via anterior communicating
d. Circle of Willis: complete anastomotic patent circle in 50%
3. Internal carotid stenosis, predominantly at carotid bulb
a. Pathobiology consistent with generalized atherosclerosis
b. Intimal arterial damage, complex mechanisms of plaque growth
c. Thrombosis and arterial plaques often develop distal to bifurcations
i. Reduced and turbulent flow, particularly at dilated carotid sinus
ii. Shear stress on opposite arterial side resists atherosclerotic plaques
4. Detection of extra- and intra-cranial carotid stenosis
a. Auscultation
i. Optimum technique
ii. Cervical bruit: 2.6 times greater risk of stroke*
iii. Conundrum with concurrent heart murmurs.
b. Doppler ultrasound
i. Duplex
1. Combines 2-dimensional image with flow characteristics
2. Blood flow velocity approximates degree of stenosis*
3. Gender variability; influenced by contralateral ICA stenosis*
ii. Continuous wave
1. Useful for major arteries
iii. Pulsed, transcranial Doppler (TCD)
1. Acoustic windows
2. Collateralization tool
c. MRA – Magnetic Resonance Angiography
i. Noninvasive, no ionizing radiation, radiofrequency imaging
ii. Blood flow is movement against the static surrounding soft tissue*
iii. Gadolinium-based contrast agents beneficial, less toxic
iv. Insensitive to calcium thrombus (vs. CTA)
v. Unable to confirm complete vs partial stenosis
vi. 97-100% sensitivity and 82-96% specificity*
vii. Claustrophobia, obesity, implant devices such as pacemaker problematic
viii. Acquisition times much faster for claustrophobic patients
d. CTA – Computed Tomographic Angiography
i. Summation of multiple thin images to visualize vessel lumen
ii. Software enhancements, technology evolution maximize resolution*
iii. Best with iodinated contrast agents; higher risk than MRA
iv. Defibrillators and pacemakers allowed during CTA
v. Imaging better for aortic arch and tortuous vessels than MRA
vi. Nearly 100% sensitivity and 63% specificity*
e. Digital angiography
i. Gold standard
ii. Increased costs and risks; ≈1% incidence of stroke*
iii. Less usage when correlation between Doppler and MRA,CTA
iv. Frequently used during stenting procedures
5. Clinical Presentations of potential carotid artery disease
a. Symptoms
i. Transient monocular blindness
ii. TIA – other neurologic symptoms
b. Primary Ophthalmic signs
i. Cervical bruit
ii. Retinal emboli, vessel sheathing
iii. Relative arteriole attenuation
iv. CRAO and BRAO
v. Hypoperfusion retinopathy
vi. Iris rubeosis
6. Guidelines for management of asymptomatic patients with known or suspected carotid artery
disease
a. Baseline Doppler duplex ultrasound
b. Reasonable to perform Doppler ultrasound in patients with cervical bruit
c. Annual repeat of ultrasound is sensible for charting disease progression
d. Ultrasound can be considered in patients with concurrent peripheral artery disease,
coronary artery disease, and atherosclerotic aortic aneurysm
7. Stroke (and stenosis) prevention guidelines*
a. Medical cost of acute and long term stroke care in US: $68.9 billion*
b. Hypertension – maintain BP 140/90 or less*
c. Tobacco smoking – quit*
d. Hyperlipidemia – reduce LDL below 100mg/dL*
e. Diabetes Mellitus – good control of blood glucose (HgA1c)is advised, however the link of
tight DM control to reduce stroke risk has not been established*
f. Hyperhomocysteinemia – while a marker of risk, there is poor evidence that vitamin
supplementation of folic acid significantly influences outcomes.*
g. Obesity and the Metabolic Syndrome – All components collectively influence risk for
carotid disease, including glucose, HTN, lipids, BMI, urinary albumin excretion, etc.*
h. Physical inactivity – moderate level of activity generally reduces risk of stroke*
i. Antithrombotic therapy – guidelines vary by individual risk profile*
i. Prevention of MI, stroke with risk factors yet no previous incident*
ii. Prevention of recurrent ischemic stroke*
1. PROFESS study (Prevention Regimen for Effectively Avoiding Second
Strokes)*
iii. Prevention of MI, stroke in aspirin-intolerant patients*
8. Revascularization of symptomatic and asymptomatic patients
a. Who should consider surgical intervention?*
b. Surgical techniques and medical therapy have both improved, studies can be outdated
c. Significance of identifying pre-surgical collateralization
d. Procedures:
i. Carotid Endarterectomy (CEA)
1. Technique and risks
a. Discrepancy of reported complications*
b. Embolic protection device
c. Guideline/recommendations for perisurgical management*
2. Selected studies
a. ECST (European Carotid Surgery Trial)*
b. NASCET (North American Symptomatic Endarterectomy Trial)*
c. VACS (Veterans Affairs Cooperative Study)*
ii. Carotid artery stents (CAS)
1. Technique and risks
a. Patient selection; placement of metal mesh stent
b. As with any procedure, outcomes and complications may be
partially surgeon dependent.
c. Guidelines/recommendations for perisurgical management*
2. Studies
a. Comparative studies of CEA and CAS are challenging due to
severity of individual conditions that differ in the cohorts
b. CaRESS study (Carotid Revascularization using Endarterectomy
or Stenting Systems)*
c. SAPPHIRE study (Stenting and Angioplasty with Protection in
Patients at High Risk for Endarterectomy)*
9. Management guidelines and post-surgical imaging to detect re-stenosis of carotid