Updated: 2/6/2020

Carotid Stenosis

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Snapshot
  • A 60-year-old man presents with a visual disturbance that occurred one day ago. He reports that he experienced a “curtain coming down” over his left eye that lasted a few minutes. His past medical history includes long-standing type 2 diabetes mellitus, hypertension, coronary artery disease, and a 20 pack-year smoking history. On physical exam, he has bilateral carotid bruits. An ultrasound duplex of his carotids shows bilateral stenosis with 40% on the right and 75% on the left.
Introduction
  • Clinical definition
    • carotid artery narrowing, or stenosis, caused by atherosclerotic plaques
  • Epidemiology
    • demographics
      • male > female
    • risk factors
      • family history
      • hyperlipidemia
      • smoking
      • hypertension
      • diabetes
      • older age
  • Etiology
    • atherosclerosis
  • Pathogenesis
    • build up of atherosclerotic plaques in the carotid arteries causes narrowing of the lumen
      • free cholesterol creates a necrotic core, contained by a weak fibrous cap
      • enlargement of the necrotic core can disrupt the fibrous cap and cause thrombosis or embolization
  • Associated conditions
    • peripheral artery disease
    • coronary artery disease
  • Prognosis
    • ↑ survival with appropriate treatment
Presentation
  • Symptoms
    • may be asymptomatic
    • if symptomatic, usually presents as transient ischemic attack or stroke
      • transient visual disturbance (amaurosis fugax)
      • unilateral muscle weakness or paresthesia
      • dizziness
      • tinnitus
      • aphasia
  • Physical exam
    • carotid bruit (typically present if there’s 60-70% stenosis)
    • motor or sensory deficits
Imaging
  • Duplex Doppler ultrasound
    • indications
      • best initial test
    • findings
      • level of stenosis
      • > 50% is moderate
      • > 70% is severe
  • Angiography (magnetic resonance or computed tomography)
    • indications
      • ultrasound unavailable or findings are unclear
Studies
  • Making the diagnosis
    • based on clinical presentation and imaging
Differential
  • Temporal arteritis
    • distinguishing factors
      • may also present with amaurosis fugax and carotid bruit
      • however, may present with other symptoms such as headache or jaw claudication
      • ↑ inflammatory markers
      • no carotid stenosis is seen on ultrasound
Treatment
  • Management approach
    • screening for asymptomatic patients is not recommended
    • all patients should receive optimal therapy for the underlying cardiovascular disease, such as hypertension or hyperlipidemia
  • Conservative
    • smoking cessation
      • indication
        • for all patients
  • Medical
    • anti-platelet therapy 
      • indication
        • symptomatic patients
      • drugs
        • clopidogrel
        • aspirin plus dipyridamole
    • statins
      • indication
        • for all patients
  • Operative
    • carotid artery revascularization
      • indication
        • stenosis > 70%
        • post-transient ischemic attack or stroke
      • surgeries
        • carotid endarterectomy (CEA)  
          • first-line for patients who can tolerate surgery
        • carotid artery stenting
          • for patients unable to tolerate CEA
Complications
  • Neurological sequelae
    • central retinal artery occlusion
    • transient ischemic attack
    • stroke
    • nerve injury
      • facial nerve 
        • specifically the marginal mandibular branch
      • hyopglossal nerve
      • recurrent laryngeal nerve
      • glossopharyngeal nerve
        • specifically nerve of Herin branch
      • sympathetic nerve
 

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Questions (4)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M3.CV.15.56) A 71-year-old woman presents with a transient episode of right arm and hand weakness that resolved in approximately one hour. Her symptoms started while she was gardening. Her past medical history is notable for hypertension, diabetes, anxiety, and dyslipidemia. Her current medications include insulin, metformin, and fluoxetine. Examination reveals a left carotid bruit. Ultrasound duplex of her carotid arteries demonstrates right and left carotid stenosis of 35% and 50%, respectively. Which of the following is the best next step in management? Review Topic | Tested Concept

QID: 103347
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Aspirin

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Bilateral carotid endarterectomy

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Left carotid endarterectomy only

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Observation

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Warfarin

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