Cerebro

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Author:
RachelRafferty
ID:
219529
Filename:
Cerebro
Updated:
2013-05-14 14:34:41
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Vascular
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Description:
Exam 2
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  1. Severe or Critical Stenosis
    (Hemodynamically Significant to VAS Surgeon)
    • Abnormally High Velocities
    • Extensive Plaque
    • Probable Calcification
    • Velocities May Approach Zero
    • String Sign
  2. Occlusion
    (Hemodynamically Significant to VAS Surgeon)
    No Flow
  3. Mottled Color Flow
    Turbulent
  4. Hemodynamically Significant
    • 50% Diameter Reduction
    • or
    • 75% Cross Sectional Area Reduction
  5. How Do You Calculate A Stenosis?
    • Waveform Analysis
    • Percent Stenosis: Diameter, Cross Sectional Area Reduction
    • Color Flow
    • VELOCITY
  6. What Is The Most Accurate Means Of Calculating A Stenosis?
    Velocity Measurements!
  7. When There Is An ICA Stenosis...
    • Proximal CCA Has Higher Pulsatility
    • CCA Has Reduced Diastolic Flow

    Intra or Extracranially
  8. Proximal Obstruction
    (Innominate A or Proximal CCA)
    • Waveform Distal Will Be Low Amp
    • Dampened Wave
    • Compensatory Flow
    • (Overestimate Stenosis On That Side)
  9. Luminal Diameter Reduction
    • % Stenosis = (1 - residual/original)x100
    • % Stenosis = (1 - residual/distal)x100
  10. Cross Sectional Area Reduction
    • % Stenosis = (1 - residual^2/original^2)x100
    • % Stenosis = (1 - residual1 x residual2 / original1 x original2)x100
  11. You Can Also Equate A Diameter Reduction By Ratio...
    • ICA Velocity/CCA Velocity = More Than 1
    • ICA/CCA Ratio Of 1.8 = A 60% Stenosis
  12. Color Flow In A Stenosis
    • Presence or Absence of Flow
    • Direction of Flow
    • Color Pattern - Changes in Saturation/Hue or Mosaic/Mottled Pattern Distal to a Stenosis
    • Facilitates Visibility of Tortuosity/Bifurcations
  13. Color flow is based on...
    Frequency shift, not velocity
  14. Bluth and UW Criteria
    Residual/Original
  15. ACAS and NASCET Criteria
    Residual/Distal
  16. ACAS = Asymptomatic Carotid Atherosclerosis Study
    Carotid Endarterectomy (CEA) in good risk patients with ICA asymptomatic stenosis of 60-90%
  17. NASCET = North American Symptomatic Endarterectomy Trial
    Symptomatic patients with ICA stenosis of 70-90% diameter reduction treated with a combination of medical management and CEA
  18. Velocity measurement variability causes inaccurate doppler stenosis parameters...
    Each ultrasound department should develop their own doppler parameters for identifying high-grade carotid stenoses
  19. Peak systolic
    • Highest within the stenosis
    • Higher the velocity, higher the stenosis
    • Once it reaches critical point of resistance to flow
    • Decrease in velocity measurement here
    • The length of lesion effects velocity
    • Longer lesion, lower velocity
  20. Peak end diastolic
    Less than 50% no significant pressure gradient = no significant velocity change

    Greater than 50% develop pressure gradient = increased velocity in proportion to degree of luminal narrowing

    Closer to 70%, the greater the increase

    Highly reliable for detection of high grade stenosis
  21. Post stenotic evaluation
    • Severity of post stenotic turbulence is proportionate to severity of the luminal narrowing
    • Greater stenosis, greater spectral broadening 
    • 70%+ very turbulent
  22. Based on ACAS (UW)
    • ICA stenosis 60-90%
    • PSV > 260 cm/sec and EDV > 70 cm/sec
  23. Based on NASCET (Bluth)
    • ICA stenosis 70-99%
    • PSV > 325 cm/sec or ICA/CCA ratio > 4.0
  24. Vertebrals
    • Normal flow around 40 or 50 cm/sec for average old person
    • Vessel diameters vary
    • May be tortuous 
    • Origin stenosis - reduced flow, damped
    • Distal obstruction - lower velocities/more pulsatile
    • Lower cardiac ejection lower velocities - bilateral
  25. Reversal of flow in vertebrals = Subclavian steal
    • Normal
    • Hesitating - perform reactive hyperemia
    • Alternating - perform reactive hyperemia
    • Reversed - full transition
  26. UW: A - Normal [0%] Sample Volume: CCA ICA
    • Normal CCA contour
    • Systolic Peak < 4.0 kHz or 125 cm/sec
    • None/Minimal spectral broadening in decelerating phase of systole
    • Window present
  27. UW: B - Minimal [1-15%] Sample Volume: CCA ICA
    • Abnormal CCA contour
    • Systolic peak < 4.0 kHz or 125 cm/sec
    • None/minimal spectral broadening in decelerating phase of systole
    • Window present
  28. UW: C - Moderate [16-49%] Sample Volume: ICA
    • Systolic peak < 4.0 kHz orr 125 cm/sec
    • Spectral broadening throughout systole
    • No window
  29. UW: D - Moderately Severe [50-79%] ICA
    • Systolic peak > 4.0 kHz or 125 cm/sec
    • Marked spectral broadening
    • Increased diastolic flow
  30. UW: D+ - Severe [80-99%] ICA
    • Systolic peak > 4.0 kHz or 125 cm/sec
    • Marked spectral broadening
    • Increased diastolic flow
    • End diastolic > 4.5 kHz or 145 cm/sec
  31. UW: E - Occlusion CCA ICA
    • Flow to zero or reversed
    • No signal
  32. Normal CCA contour
    First zero slope after systole is below midslope
  33. Abnormal CCA contour
    First zero slope after systole is above midslope
  34. Bluth: Systolic Velocity Ratio
    • (VICA/VCCA) > 1.8 ... 60%
    • (VICA/VCCA) > 3.7 ... 80%
  35. Bluth: Diastolic Velocity Ratio
    • (VICA/VCCA) > 2.4 ... 60%
    • (VICA/VCCA) > 5.5 ... 80%
  36. Lesion
    to hurt, loss of function of a part
  37. When plaque is found in the ICA...
    Patient should be seen annually
  38. Carotid dissection
    • Occurs when a false lumen develops beneath the intima of a vessel
    • False channel extends for variable distance
    • Elevates the intima
    • Compromises the true lumen
    • Thrombosis may form in false lumen
  39. Carotid dissection
    • Affect on flow depends on severity of luminal compromise
    • Vessel may thrombose causing complete occlusion
    • If not occluded, flow may be maintained through true or false lumen
    • Spontaneous dissection usually past bulb
  40. Causes of Carotid Dissection
    • Trauma - causing an intimal rip or tear
    • Dissecting aneurysm of ascending aorta
    • Spontaneous means that the true cause is not known
  41. Symptoms of carotid dissection
    • Atherosclerotic disease - TIA/CVA
    • Headache 
    • Severe neck and scalp pain
    • Sudden onset or cessation of bruit
    • Horner's Syndrome - drooping of ipsilateral eyelid
  42. Arterial Venous Malformation
    • Malformation: defective formation, deformity, acquired during development
    • Communication between artery and vein
    • Uncommon occurrence
    • True AVMs are considered CONGENITAL
    • May be intracranial or extracranial
    • Decrease in resistance to flow
  43. Arterial Venous Fistula
    • Fistula: abnormal tube like passage, created surgically and others occur as a result of injury or as congenital
    • Single connection between artery and vein
    • Caused by penetrating injury, aneurysm, infection, MANMADE (iatrogenic)
  44. Congenital AVMs
    • Normal development of vascular system is altered
    • Capillaries undergo changes
    • Proper changes result in multiple or single AVMs
    • Later stage has fewer AVMs
    • May have tortuous channels
    • May involve artery
  45. Intracranial AVMs
    • Symptoms vary with location and extent
    • Focal epileptic seizures
    • Hemiparesis
    • Aphasia
    • Amnesia
    • Bruit
  46. Cavernous Sinus AVM Symptoms
    • Glaucoma
    • Diplopia
    • Headache
    • Bruit (through eye)
    • Surgery may not be possible
  47. Characteristics of AV Extracranialy
    • Pulsating mass
    • Port wine birthmark - increase in skin temp
    • Venous engorgement
    • Pain and swelling
    • Disfigurement
  48. Characteristics of AV Flow Changes
    • Increase in flow to feeding artery with dialation
    • Reverse flow artery distal to AV
    • Venous distension in distal vein
    • Valvular incompetence
    • Increased pulsatile flow in proximal vein
    • Bruit loudest over site of AV communication
    • Patient may have pulsatile tinnitus
    • May feel thrill over area
    • Causes an increase in cardiac output - enlarged heart and CHF
  49. Treatment of AV Communications
    • Possible brain surgery - location, size, condition of AVM
    • Endovascular microembolization - coils, embolic therapy
  50. Carotid Body Tumor
    • Relatively rare - 600 annually
    • Neoplasm - could be bilateral
    • Occurs at bifurcation - carotid body size of grain
    • Neural crest paraganglion cell hyperplasia
    • Highly vascularized mass
    • Mass may cause hoarseness
    • May cause vocal cord or facial paralysis
    • Patient may display Horner's syndrome
  51. Carotid Body Tumor - Group 1
    Consists of relatively small tumors, which are minimally attached to the carotid vessels - surgical excision is not difficult
  52. Carotid Body Tumor - Group 2
    Tumors are larger, with moderate attachments. These tumors may require a temporary intraluminal carotid shunt during surgery
  53. Carotid Body Tumor - Group 3
    Tumors are very large neoplasms that encase the carotid arteries and often require arterial resection and grafting
  54. Carotid Body Tumor
    • Radiation therapy has not been successful for reducing or slowing tumor growth
    • Bilateral in 5% of patients, 32% in families
    • May lead to death
    • Surgical resection treatment of choice
  55. Subclavian steal
    • Stenosis or occlusion of subclavian or innominate artery
    • Results in reversal of flow patterns due to pressure gradient changes
    • Atherosclerosis most common cause
  56. Symptoms of Subclavian Steal
    • Vertigo
    • Limb paresis
    • Visual disturbances
    • Ataxia
    • Syncope
    • UE limb claudication
  57. Innominate occlusion
    • Reduces total cerebral blood flow by 18%
    • Severely affects hemodynamics extracranially
    • Patient is usually asymptomatic
    • Three distinct collateral patterns: Reversed Vertebral (Most common), Reverse right vertebral and right carotid artery, antegrade right vertebral and retrograde right ICA/CCA
  58. Subclavian steal
    • Subclavian occlusion with reversed vertebral
    • Total cerebral flow is decreased by 6% due to reversed vertebral and subsequent subclavian steal
    • No surgery for asymptomatic patients
  59. Subclavian steal
    • Most labs consider 20mmHg pressure difference between brachial arteries
    • Reactive hyperemia - pump ipsilateral cuff 20 mmHg above systole for 3 minutes, cuff is deflated while monitoring ipsilateral vertebral artery
  60. Subclavian Steal Waveforms
    • No steal - normal after RH no change
    • Limited steal - after RH some flow reversal
    • Latent steal - alternating before, mostly reversed after
    • Completed steal - mostly before, totally reversed after
  61. Subclavian Steal Symptoms
    • Syncope
    • Dysphasia
    • Ataxia
    • Dysarthria
    • Facial sensory problems
    • Claudication
    • Muscle atrophy
    • Skin changes
    • Pain at rest
  62. FMD
    • Most common in renal arteries
    • Found affecting ICA
    • Known as string of beads
  63. FMD Variants
    • Intimal fibroplasia
    • Medial hyperplasia
    • Medial fibroplasia - most common
    • Perimedial dysplasia
  64. FMD Location
    • Lesions in mid to distal portion of cervical ICA
    • May extend to skull
    • May be confined to proximal ICA
    • Rarely affects intracranial vessels
    • May lead to spontaneous dissection of ICA
  65. FMD Patients
    • Female most common - mid adult age
    • May be for estrogen
    • May be caused by stress on ICA with poor medial blood
  66. FMD Symptoms
    • Localizing - TIA
    • Nonlocalizing - dizziness and lightheadedness
    • Expressive aphasia, blurred vision, roaring in ear, and vertigo
    • Completed stroke
    • Bruit in 75% or more
    • May be hypertensive
  67. FMD Characteristics
    • Usually bilateral - one side worse
    • May have string of beads appearance
    • May have atherosclerosis changes at bifurcation
    • May have dissection
    • Usually treated with anticoagulants
    • May be treated with surgery
    • Repaired with balloon
  68. Carotid Artery Aneurysm
    • Rare!
    • Two types: Fusiform or Saccular
    • Saccular is most common: at biurcation bilaterally
  69. Aneurysm Symptoms
    • Pulsating mass in neck
    • Bruit
    • May see bulge in neck
    • Pain over area
    • Cerebral ischemia may result, distal emboli
    • Compression adjacent
  70. Aneurysm - Differential Diagnosis
    • Carotid Body Tumor
    • Peritonsillar abscess
    • Lymph node or tumor
    • TORTUOUS VESSELS
    • Treatment = surgery
  71. Carotid kink
    • Sharp angulation of vessel
    • Not very common
    • May cause cerebral insufficiency
    • Affects one or more segments of the artery
    • Creates stenosis
    • Commonly occurs 2 - 4 cm above bifurcation!!!
    • May be bilateral
    • May be acquired (not congenital)
  72. Causes of Carotid Kink
    • Loss of vessel elasticity
    • Atherosclerotic degeneration
    • Subintimal disruption from plaque
    • Artery elongates and folds
    • Patients usually 50+ years old
    • No surgery for asymptomatic patients
  73. Tortuosity and Coils
    • More common than kink
    • Usually bilateral
    • May be congenital
    • May worsen with age
    • Benign condition
    • No treatment necessary
  74. Interpretation of Moderate
    • 50%
    • Slight increase in spectral
    • Disease is present
    • Patient may be
    • Need follow up at
  75. Hemodynamically Significant
    • Velocity increases and flow decreases are not worthy of meaning or mention until a stenosis reaches 50% diameter reduction
    • Vascular surgeons hemodynamically significant is when surgery is needed (80-99%)
  76. Moderate to Severe
    • Greater than 50%
    • Increase in velocity, due to stenosis
    • Extensive
    • PSV may be 2-3 times higher than normal
    • Patient may be

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