Carotid Artery Occlusive Disease Flashcards
Cerebrovascular disease constitutes the ____ leading cause of death
in the U.S.
3rd
Causes of Atherosclerosis
Genetics Tobacco Abuse Hypertension Diabetes Hyperlipidemia ^ homocysteine levels Diet and obesity Female Job/environment
Diabetes and CAOD
- Increased lipoproteins
- Inhibits basement membrane function
- Platelet aggregation
- Cytokine-enhanced smooth muscle cell proliferation
- Enhancement of thrombogenic factors II, V, and X
Tobacco Abuse and CAOD
• Carbon monoxide → arterial wall injury, increased plasma flux, entry of LDL, intimal hyperplasia • Increased platelet reactivity • Lowers HDL levels • Peripheral vasoconstriction
Risk Factor Reduction
Platelet Inhibitor Smoking cessation Control hypertension Control diabetes Decrease hyperlipidemia, LDL level, and triglycerides Diet Aerobic exercise Multivitamin Vitamin E and Vitamin C—antioxidants, increase vascular elasticity B-complex vitamins with B6, B12, and folic acid—decrease homocysteine levels Omega 3 fish oil
Medical Management:
Coated Aspirin
Inhibits cyclooxygenase activity which blocks prostaglandin metabolism and synthesis of thromboxane A2—stimulator of platelet aggregation
• Mainly COX 1 (platelets), COX2 (inflammatory cells) 50:1
Medical Management:
Ticlopidine (Ticlid)
Inhibits adenosine diphosphate (ADP), which plays a central role in platelet aggregation and activation
• Complications: rash, diarrhea, life-threatening neutropenia (can be fatal)
Medical Management:
Persantine
Not shown to be more affective than aspirin alone or in combination
Medical Management:
Clopidigrel
- Blocks ADP receptor P2Y12 , an extra carboxymethyl side group
- 6 times more potent than Ticlid with fewer side effects
- CAPRIE trial (Clopidogrel vs Aspirin in Patients at Risk of Ischemic Events)
- 8.7% risk reduction in vascular death, ischemic stroke, and myocardial infarction versus aspirin
Asymptomatic Patient
NASCET study, European Carotid Surgery trial, CASANOVA study
• Surgical Intervention—superior results to medical management when stenosis is 70% or greater
• Stroke rates at 1, 3, and 5 years were 23%, 37%, and 45%, respectively in the
asymptomatic patient
Symptomatic Patient
TIA, RIND
• Symptomatic patient with:
70% stenosis— 35% risk of stroke in 1 year
80% stenosis— 46% risk of stroke in 1 year, 62% risk in 2 years
90% stenosis— 75% risk of stroke within 1 year
Transient Ischemic Attack
– Principal cause is a brief disruption in perfusion
– Initial symptom of carotid disease and precursor of an impending stroke
– Signs and symptoms typically resolve within hours
– Focal neurological deficit lasting less than 24 hours
– Complete recovery
Symptomatic Patient
CVA/Stroke
- High likelihood of a 2nd stroke with worsening deficits
- Periumbra region, “scar down period” to prevent an ischemic infarction to worsen/extend by way of a hemorrhagic infarction during reperfusion
Stroke
Acute neurological deficit of
vascular origin persisting longer
than 24 hours
Major Stroke
defined as neurological deficit which lasts longer than seven days and increases the NIH stroke scale number by >4
Minor Stroke
defined as a neurological deficit lasting >24
hours and increases the NIH stroke scale by <3
Symptomatic Patient
Stroke in Evolution
“stuttering stroke”
“catch 22” - damned if you do, damned if you don’t
Diagnosis of Carotid Artery Disease
Many imaging tools are used to diagnosis disease • Choose optimal method • Imaging tools used with good results • Angiography • Duplex ultrasonography
CTA
MRA
Doppler
Indications: carotid bruits (cardiac source, stenosis, tortuosity), symptomatic, continued monitoring and follow-up
Duplex Scanning: non-invasive, can characterize % stenosis/consistency/ulcerations, 92-95% accurate
Contrast Studies
Advantage • To confirm doppler findings • “Roadmap” for surgery • Visualization of aortic arch, extracranial vessels (subclavian and vertebral arteries), and intracranial vessels Carotid cerebral angiography • Still the “gold standard” • Invasive • Most institutions forgo this, provided that non-invasive preoperative testing is of diagnostic quality and correlates with the patients clinical presentation Cat scan angiography MRA with gadolinium
Surgery:
Carotid Endarterectomy
- Shunt
- Patch graft angioplasty
- Anti-platelet drugs
- Cranial nerve injury
- Stroke, mortality
• The combined perioperative risk of death and stroke was 3% to 3.5% in asymptomatic patients, compared with 5.18% for symptomatic patients - Post-operative follow-up
• Dopplers—6wks, 6months, 1 year, then annually
Surgery:
Carotid Stenting
- Being used with increasing frequency in many centers worldwide
Still very controversial for when it should be used
Initially, significantly higher stroke morbidity and mortality rate - Carotid Revascularization Endarterectomy vs. Stent Trial (CREST)
• Cerebral anti-embolism device/cerebral protection
• Ongoing trial for several more years funded by NIH and guidant
• Initial study—13% stroke and death rate in patients older than 80yrs. Trial has stopped enrolling octogenarians.
• 30-day morbidity and mortality rate 5.5% for symptomatic patients, 2.8% for asymptomatic patients. These results
compare very well with surgical series.
• Average cost for carotid endarterectomy $21,670, whereas carotid angioplasty with stenting costs $36,140
Possible indications for carotid stenting
- Class III or IV congestive heart failure
- Open heart surgery needed within 6 wks
- Recent myocardial infarction (>24hr and <4wks)
- Unstable angina (Class III or IV)
- Severe pulmonary disease
- Contralateral carotid occlusion
- Contralateral laryngeal nerve palsy
- Radiation therapy to neck
- Previous CEA with recurrent stenosis
- High cervical ICA lesions or CCA lesions below the clavicle
- Severe tandem lesions
Treatment of Carotid Artery Disease
Carotid stenting
• Less invasive, percutaneous
• Developed for patients at high risk for surgical intervention
• Safety of procedure has improved with advent of embolic protection
devices
Preoperative Evaluation
- Cardiac clearance—stress testing
- Pulmonary function testing
- Beta-blocker protocol
