Carotid, Subclavian, and Vertebrobasilar Disease

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Carotid, Subclavian, and Vertebrobasilar Disease

• Kelley Hodgkiss-Harlow
• 9/30/2009

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Carotid Disease History

• 1875Gowers case report of R hemiplegia/L
  blindness
• 1914Hunt recognizes syndrome of TIAs as prodrome
  to stroke
• 1937Moniz Arteriography used to diagnose
  carotid artery occlusion
• 1954Eastcott publishes first report of
  successful CEA

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Pathology

• Atherosclerosis 90
• Deposition fat? intima?fatty plaque with
  intermittent hemorrhage/ulceration
• Bifurcation predominance-secondary to arterial
  geometry, velocity profile, and wall shear stress
• Other 10
• FMD
• Mechanical
• Inflammatory
• Radiation

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Stroke

• 3rd leading cause of death in USA
• Age is risk factor
• Malefemale ratio about 1.51
• gt65 y/o incidence 150-200/100,000
• High rate of recurrence if no intervention
• 10-20 within one year, 20-42 within 5 years
• Roughly accepted 10/yr recurrence risk
• Majority recur within one year
• High mortality rate with recurrence
• 35-65

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Stroke distribution

• MCA contralateral sensory/motor loss, head and
  eye deviation toward infarcted side
• leftaphasia/neuropsych symptoms
• ACA rare, contralateral lower extremity
  weakness/sensory, urinary incont, apathy, mutism,
  gait apraxia
• PCA mesencephalon, thalamus, occiptal and
  temporal lobeshomonymous visual field deficit,
  alexia, prosopagnosia, amnesia, hallucinations
• Watershed areas ACA/MCA and MCA/PCA borders
• Lacunar (brain stem, basal ganglia) pure motor,
  pure sensory, ataxis hemiparesis, and dysarthria.

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TIA

• Definition Transient focal neurologic deficit
  of either anterior or posterior circulation
• Rochester study TIAs followed for five yr
• Incidence stroke 36
• 51 of these occurred within first year
• Lit review annual stroke incidence in pts with
  TIAs ranges from 5.3-8.6/yr for first 5 years
• Approx 1/3 pts with TIA will suffer stroke within
  5 years

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TIA II

• Embolic theory of transient cerebral ischemia
  (versus mechanical flow reduction)
• Atheromatous debris, thrombus, or plt aggregates
• Ischemic attacks stop after occlusion
• TIA vs small stroke? Cerebral infarction and
  atrophy is correlated with percent stenosis and
  h/o TIAs
• 2 e/o stroke on CT with pts with mild stenoses
• 58 in pts with asymptomatic high-grade stenoses
• Therefore, important to identify asymptomatic
  lesions BEFORE TIA occurs

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Timing of CEA

• Historically weeks to months delay after TIA or
  stroke
• ipsilateral hemorrhage and extension of the
  infarct supported in several series
• Old data prior to current imaging studies
• No RCT addressing the question
• Large meta-analysis 2003
• No diff between rates of stroke or death for pts
  with stable stroke symptoms when CEA performed
  early (lt3-6 weeks) or delayed (gt3-6 weeks)
• Pooled analysis of NASCET and ESCT data
• Greatest benefit from surgery in group randomized
  within 2 wks of surgery and this benefit
  decreased with further delay from symptom onset

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Imaging Studies

• CT scan90 cortical ischemic infarctions are
  detectable with a clinical neurologic event after
  24h
• Hypodensities, mass effects, loss of distinction
  between cortical gray and subcortical white
  matter
• Hemorrhagic areas of reperfusion
• Only dx 50 brainstem infarcts
• CTA vs. Angiography Overal accuracy for correct
  stenosis 90-96, risks of complications avoided
• MRA Sensitivity 83-97 and specificity 92-98
  for detecting flow voids, tends to overestimate
  when compared to angiography

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Symptomatic Disease

• NASCET2226 pts randomized to medical care or
  CEA.
• Patients had either a transient ischemic attack
  or stroke within 4 months of enrollment and a
  30-99 internal carotid artery stenosis.
• For patients with a gt70 stenosis, carotid
  endarterectomy reduced the risk of any
  ipsilateral stroke from 26 to 9 at 2 years
  (Plt0.001).
• Conclusion CEA better if symptomatic with
  stenosis gt70

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Asymptomatic disease

• Natural history studies 30-50 pts who have
  suffered a stroke did NOT have TIA prior
• 20 pts with bruit will have hemodynamically
  significant stenosis of the carotid bulb
• ACAS trial (1995) Called off after 2.7 yrs f/u
• 5 yr risk for ipsi stroke, any periop stroke, and
  death was 5.1 surgical group c/w 11 medical
  group.
• Absolute risk reduction of 5.9 and relative risk
  reduction of 53 in favor of CEA.
• Combined neurologic morbidity and mortality 1.52
  for surgery.

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Asymptomatic Disease II

• Conclusion CEA better if can offer with
  morbidity/mortality lt1.5, recc if gt60 stenosis
• Corresponds to 80 stenosis when using
  standardized duplex criteria
• ASCT (2004) 5 yr trial results confirm and
  extend ACAS results.
• 5 yr risk for ipsi stroke, any periop stroke, and
  death was 6.4 surgical group c/w 11.8 medical
  group.
• Benefit in pts gt60 stenosis
• Most benefit in pts gt75 y/o

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Duplex Criteria

• Individualized to each vascular laboratory with a
  program of internal quality control.

ICA stenosis Peak Systolic Velocity End diastolic velocity
lt50 lt125
50-74 gt125 lt125
gt75 gt125 (gt300) gt125
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Pre-Op Medications

• Antiplatelet Therapy
• Cochrane meta-analysis ASA 81mg statistically
  significant benefit in reducing rate of stroke
  from any cause, but not death or cardiac events
• 81mg as effective as 325mg with less bleeding
  complications/risks
• Statin
• Reduction in in-hospital mortality, perioperative
  stroke and death rates, but not in-hospital
  cardiac events
• Multivariate analysis 3-fold reduction in
  stroke, 5-fold reduction in death

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CEA Techniques

• Vertical vs. Horizontal Incision
• Identification and Mobilization
• Cervical lymph nodes
• Hypoglossal nerve
• Gaining distal ICA exposure
• Digastric muscle division
• Mandibular subluxation
• EndarterectomyEversion vs. Patch
• No difference in rate of stroke/death
• Advantagefaster, less exposure, no suture line
  on ICA
• Disadvantagetech challenging, mobilization of
  bulb, less visualization of endpoint, shunting
  cumbersome
• Shuntingsnow plowing the intima

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Selective Shunting

• Local/Regional Anesthesia (0-1.1 permanent
  deficit)
• 10 all procedures done
• Lesser fluctuations in blood pressure
• EEG Monitoring (1.5-3.5)
• Wide threshold between EEG monitoring becoming
  abnormal vs. infarction
• ?sensitivity/specificity
• Stump pressure measurements (0.8-2)
• 50mmHg based on correlations with EEG monitoring,
  status of contralateral artery, and reported
  outcomes

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To Shunt or Not To Shunt

• Clamping ischemia is uncommon cause of
  perioperative stroke
• 93-96 pts tolerate carotid clamping without
  shunt under local/regional anesthesia
• Embolization or thrombosis usually due to
  technical difficulties
• Shunt does not protect or contribute to stroke
  riskno superiority in either technique between
  selective shunting vs. routine shunting.
  (Cochrane stroke group)

Risk Stroke rate
Low patent contra ICA and stump pressure gt50mmHg 1.1
Intermediate occluded contra ICA, pressure gt50mmHg 4
High occluded contra ICA, pressure lt50 mmHg 4
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Intraoperative Assessment

• Operative Arteriography
• If routinely performed, a reduction in mortality,
  stroke rate, and fatal strokes has been noted in
  several studies
• Angioscopy
• Direct visualization of the luminal surface
• Increases cross-clamp time, no info on patterns
  of blood flow
• Duplex Ultrasonography
• Detection and correction of turbulent blood flow
  and anatomic defects lead to decreased occlusions
  and restenosis

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CEA vs. CAS

• Randomized clinical trials to gain evidence on
  which to base clinical decisions.
• CAS vs. CEA?need to enhance our understanding of
  their roles.
• CAVATASangioplasty alone vs. surgery, horrible
  results both arms, of historical interest only

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SAPPHIRE (Stenting and Angioplasty with
Protection in Pts at High Risk for Endarterectomy)

• Initially, data showed results for stenting
  statistically significantly superior to those of
  CEA.but
• Primary endpoint was amalgam of short and
  intermediate term results (periprocedural stroke,
  MI, or death, and one year ipsilateral stroke or
  death)
• No statistically significant difference in
  outcome in any individual endpoint (death,
  stroke, or MI).
• Majority of MIs were non Q-wave and of doubtful
  significance.
• lt30 high-risk pts had symptomatic dz, treatment
  groups are not equal in terms of
  comorbidities/age
• No medical management arm

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Symptomatic Trials

• EVA-3S gt60 symptomatic stenosis equally
  eligible pts
• 30 day Stroke/death rates 3.9 (CEA) vs. 9.6
  (CAS)
• 6 months 6.1 vs. 11.7
• Butless experienced surgeons, no CPD
• SPACE symptomatic pts randomized CEA vs. CAS,
  failed to prove non-inferiority
• CPD in only 27

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CREST

• 2500 pts equally eligible for CEA vs. CAS,
  enrolled based on NASCET/ACAS guidelines
  (50/70)
• Lead-in results suggest that older pts suffer
  worse outcomes (P0.0006)

Age (N) Stroke/Death
lt60 (120) 2 (1.7)
60-69 (229) 3 (1.3)
70-79 (301) 16 (5.3)
gt 80 (99) 12 (12.1)
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Conclusions CAS vs. CEA

• The low morbidity and mortality rates in both
  nonrandomized and randomized series studying CEA
  for both asymptomatic and symptomatic pts must be
  equaled for CAS.
• 30d stroke and stroke/mortality rates for CAS
  appear to be marginally statistically
  significantly higher than those associated with
  CEA (1.3)
• Accepted indications
• Surgically inaccessible lesion
• Hostile Neck
• Restenosis
• Medical high risk (hard to define)
• Participation in RCT

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Vertebrobasilar Ischemia

• Symptoms Commonly manifested as vertigo, visual
  disturbances, progressive neuro deficit
• Mechanisms
• Microembolization from heart or more proximal
  arteries. Less common.
• innominate, prox subclavian, and vertebrals
• Low-flow lack appropriate inflow from the
  vertebral artery and have inadequate compensation
  from the carotid.
• More frequent
• Stenosis/occlusion of vert, also extrinsic
  compression
• Orthostatic hypotension, antihypertensive meds,
  arrythmias, CHF, pacemaker malfunction, anemia

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Evaluation of Patients

• Dizziness, vertebral artery stenosis are common
  complaints/findings
• Imaging brain to r/o tumor, investigate for
  infarctions
• Check bilateral arm BPs to r/o subclavian steal
  syndrome
• Document reversal of flow by duplex
• Extrinsic compression by osteophytes
• Turning head side to side, slowly, then briskly
  to differentiate from BPV
• Confirm with angiogram

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Global ischemia

• Drop attacks comprise roughly 30 of
  presentations
• One or both internal carotid arteries occluded or
  with severe siphon stenosis.
• Vertebral arteries important pathways for
  cerebral revascularization when they are
  critically stenosed or occluded.
• Minimal anatomic req to justify vert
  reconstruction is gt60 stenosis in dominant if
  contra is hypoplastic, or gt60 in both.

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Angiography

• Most common athersclerotic lesion is stenosis of
  its origin
• Presence of post-stenotic dilation proximally is
  suggestive of hidden stenosis
• Extrinsic compression seen at V2multiple
  views/manipulation necessary
• V2-V3 segments site of traumatic injury from
  periosteum/adventitia fixation
• V3 usually area of reconstitution secondary to
  collaterals from occipital artery

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Angiography
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Treatment

• Anticoagulation
• Trial of medical therapy prior to pursuing any
  surgical intervention
• Most effective for lesions that cause symptoms
  through embolization or thrombosis of small
  arteries
• If definite clinical syndrome, MRI documenting
  absence of alternate pathology, arteriography
  with structural lesion, and persistent symptoms
  on anticoagulation?surgery

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Surgical Options

• Transposition of Vertebral Artery into the Common
  Carotid Artery
• Origin stenosis
• Supraclavicular at level of C6
• Patency 90-97, stroke risk 2, mortality risk
  lt1
• Complications Horners, lymphocele
• Distal Vertebral Artery Reconstruction
• GSV
• Level of C2
• Endovascular interventions?

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Subclavian Disease

• Atherosclerotic disease leftgtright
• Asymptomatic lesions even with asymptomatic
  steal?treatment deferred
• Subclavian steal
• Retrograde blood flow associated with proximal
  subclavian stenosis or occlusion
• Upper extremity ischemia (71), VBI (44),
  Hemispheric TIA (29)

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Subclavian Steal Syndrome

• Physical exam
• Blood pressure differential gt20mmHg
• 2-3x more common on the left
• Embolic phenoma to hands
• Duplex ultrasonography
• Reversal blood flow within vertebral
• Monophasic waveforms in subclavian a.
• High-frequency blood flow pattern
• Arch aortography with selected views

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Treatment

• Treat ICA lesion first!
• If symptoms persist
• Transposition of subclavian artery onto the
  common carotid
• Approx 100 patency rate at followup
• Carotid-Subclavian bypass
• Approx 94 patency at 10 years
• Axilloaxillary bypass
• Setting of previous extensive neck surgery or
  radiation
• Long-term durability inferior
• Subclavian artery stenting/angioplasty

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Any Questions?