Carotid Endarterectomy

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Carotid Endarterectomy
  • Indications
    •  7North American Symptomatic and Carotid Endarterectomy Trial (NASCET) guidelines:
      • For patients with hemispheric or retinal transient ischemic attacks (TIAs) or a mild stroke within three months and high-grade stenosis (> 70%): endarterectomy reduced rate of fatal & non-fatal strokes (17% at 18 months) and death by any cause (7% at 18 months) when compared to best medical management
Carotid Stenosis

Carotid Stenosis in 3D from 3D vascular atlas image using volume rendering techniques (3D CT):  courtesy of Elliot Fishman, MD,(c) 2000, Department of Radiology, Johns Hopkins University (http://www.ctisus.org), used with permission

  •  Variable rationale for surgery, depending on the center
  •  Variable complication rates between institutions
  •  Some studies have found that many procedures were done for inappropriate reasons (frequency = 33%)* 
    •   50% of procedures done for asymptomatic bruits1 {4% stroke rate/year without surgery; surgical complication rate > 9%; note this is a 1988 citation}
  •  Singular rationale for carotid endarterectomy: prevention future strokes
    •  Prodromal events for future strokes:
      • transient ischemic episodes/attacks (TIAs)
      • reversible ischemic neurological deficit
  •  Internal carotid artery occlusion extent of > 75%: probably associated with greater stroke risk than likelihood of surgical ischemic complications: procedure probably warranted
  • Conclusion: Carotid endarterectomy warranted if occlusion extent > 75%, otherwise medical management  + observation indicated
  • 2Other indications for carotid surgery:
    1. trauma
    2. loops & kinks
    3. acute occlusion
    4. intimal tears
    5. spontaneous dissection
2Contraindications: Carotid Endarterectomy
acute infarction "Stroke-in-evolution" with infarction Internal carotid artery occlusion Severe ipsilateral carotid siphon lesion Limited life expectancy Major operative risk
  • 7Symptoms of Carotid Stenosis:
    • Definition:
      • Symptomatic-- 1 or more ischemic episodes appropriate to lesion distribution;
      • Asymptomatic -- Only non-specific visual complaints, dizziness, syncope not associated with transient ischemic attack (TIAs) or stroke
    • Symptomatic presentations:
      • Motor deficit: {paralysis, clumsiness, weakness) of one extremity or both extremities on one side {opposite side of involvement }
      • Sensor deficit {numbness, including sensation loss or paresthesias involving  one or both extremities on one side of the body (opposite side of involvement)
      • Vision loss in one eye part of one eye (amaurosis fugax; definition -- amaurosis   = blindness occurring without apparent clinical lesion, i.e. from disease of  optic nerve, retina, spine or brain;amaurosis fugax =  transit episode of monocular blindness or partial blindness)
      • Vision loss off to one side (homonymous hemianopsia): affecting the right halves or the left halves of the visual fields of the two eyes {hemianopia = defective vision/blindness in half of the visual fields} 
      • Aphasia: language deficit extends from mild  effects to include complete speech loss
  • 7Diagnostic/Evaluative Imaging Methodologies:
    • Cerebral angiography:-Still probably the  Gold standard for carotid/server vascular disease evaluation
      • major drawback: procedural risk {1.3% risk of temporary neurological complication; 0.1% risk of permanent stroke}-- Risk sufficient to prevent angiography for use in screening
    • Carotid Doppler Ultrasound: widely used screening method; blood flow velocity analysis a loss assessment of stenosis extent
    • Magnetic Residence Angiography:noninvasive technique which produces angiographic images
  • 7Treatment Overview:
    • Surgical Intervention:
      1. carotid endarterectomy
      2. balloon angioplasty
    • Medical Treatment
      • Aspirin
        • diminishes platelet aggregation {reduces likelihood of clot formation}; dosage 325 mg orally/day
        • reduction those stroke incidents following TIAs  by 25%-35%
      • Ticlopidine (Ticlid)
        • Antiplatelet agent, possibly more effective than aspirin 
        • Risks: neutropenia {reduced white count}
        • Other factors: more expensive compared to aspirin
      • Antihypertensive treatment
      • Optimized control of diabetes
      • Reduction in serum lipids with cholesterol-lowering diet & antilipidemic drugs
      • Patients with asymptomatic atrial fibrillation should be managed with anticoagulant drugs
  • Factors influencing outcome in carotid endarterectomy
    • 7Summary of Medical Risk Factors:
      • angina, myocardial infarction within six months, congestive heart failure, severe hypertension, pulmonary disease, AGE > 70, severe obesity
    • 7Summary of Neurologic Risk Factors:
      • progressive neurological deficit, recent stroke less than seven days before surgery, frequent transient ischemic episodes (TIAs), resold neurological deficit < 24 hours before surgery, generalized CNS {cerebral} ischemia
      •  
    •  3Extent of carotid disease
      •  Morbidity/mortality for stroke-in-progress: 21%
      •  Morbidity/mortality for patients with TIAs or asymptomatic bruits:< 6.5%
      •  Acute carotid occlusion accompanied by significant preoperative neurologic deficit: postoperative mortality rate > 20% {if flow is restored, neurologic improvement occurs in nearly 60% of cases}
      •  Untreated acute carotid occlusion: mortality rate up to 55% {note significance of carotid endarterectomy in these patients}4
    •   Age
      •  Mortality highly correlated with increasing age
        • Mortality rate for patients 50-60 years old: 0.8%
        • Mortality rate for patients nine years old or greater: 4.17%
        • All mortality and carotid endarterectomy may result from factors directly related to patients age5
    •   Hypertension/carotid disease
      •  Patients preoperatively hypertensive are more likely to be postoperatively hypertensive
      •  Postoperative hypertension: associated with increased incidence of neurological deficits
      •  Hypertension postoperatively may be associated with hemorrhagic stroke {secondary to sudden increase in perfusion pressure}
    •   Diabetes mellitus: 
      •  Diabetic patients (asymptomatic preoperatively) -- postoperative neurological deficits-frequency 2.6% {0% in non-diabetic individuals}
      •  Increased long-term death rates in these populations were typically attributable to fatal myocardial infarction

 

"A plane is created between the atheroma and the remaining media of the vessel.  The plane should be kept immediately below the plaque so that the remaining wall is not to thin and at risk for rupture.The lower end of the plaque is separated and used as a handle to core out the remainder in a cephalad direction"

 "The extensions of plaque into external carotid and superior thyroid are gently teased out and separated with gradual traction to feather the ends in minimize intimal flaps."

"The distal end of the core of plaque is teased out in the same fashion"

Note: images & commentary courtesy courtesy of vesalius (http://www.vesalius.com), used with permission

  • Primary Reference: Katz, J.,  Evaluation Risk Assessment of Patients with Vascular Disease in Principles and Practice of Anesthesiology (Longnecker, D.E., Tinker, J.H. Morgan, Jr., G. E., eds)  Mosby, St. Louis, Mo., pp. 201-218, 1998.
  • 1Winslow, CN, Solomon, DH, Chassin, MR, et al: The appropriateness of carotid endarterectomy, N. Eng J Med 318:12,721, 1988.
  • 2 Ferguson, G: Clinical Neurosurgery, vol 29, Baltimore, 1982, Williams & Wilkins
  • 3Fode, NC, Sundt , TM, Robertson, JT, et al: Multicenter retrospective review of results and complications of carotid endarterectomy in 1981, Stroke, 17:370, 1986.
  • 4Norrving, B, Nilsson, B: Carotid artery occlusion: acute symptoms and long-term prognosis,Neurol. Res 3:229, 1981.
  • 5Glaser, R.B, Feigal, D: Age-specific morbidity and mortality.  An analysis of the California hospital discharge date tapes from the office of statewide health planning and development {unpublished data found in Primary Reference above}
  • 6Campbell, DR, Hoar, CS Jr, Wheelock, FC: Carotid artery surgery in diabetic patients, Arch Surg. 119:1405, 1984.
  • 7 UCLA Neurosurgery: Cerebrovascular & Stroke Diseases & Disorders -- Carotid Stenosis (http://www.neurosurgery.medsch.ucla.edu/Diagnoses/Cerebrovascular/CerebroDis_3.html)
  •  Note that above references 1-6 are second sourced from Katz, J.,  Evaluation Risk Assessment of Patients with Vascular Disease in Principles and Practice of Anesthesiology (Longnecker, D.E., Tinker, J.H. Morgan, Jr., G. E., eds)  Mosby, St. Louis, Mo., pp. 201-218, 1998.

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