-
Severe or Critical Stenosis
(Hemodynamically Significant to VAS Surgeon)
- Abnormally High Velocities
- Extensive Plaque
- Probable Calcification
- Velocities May Approach Zero
- String Sign
-
Occlusion
(Hemodynamically Significant to VAS Surgeon)
No Flow
-
Mottled Color Flow
Turbulent
-
Hemodynamically Significant
- 50% Diameter Reduction
- or
- 75% Cross Sectional Area Reduction
-
How Do You Calculate A Stenosis?
- Waveform Analysis
- Percent Stenosis: Diameter, Cross Sectional Area Reduction
- Color Flow
- VELOCITY
-
What Is The Most Accurate Means Of Calculating A Stenosis?
Velocity Measurements!
-
When There Is An ICA Stenosis...
- Proximal CCA Has Higher Pulsatility
- CCA Has Reduced Diastolic Flow
Intra or Extracranially
-
Proximal Obstruction
(Innominate A or Proximal CCA)
- Waveform Distal Will Be Low Amp
- Dampened Wave
- Compensatory Flow
- (Overestimate Stenosis On That Side)
-
Luminal Diameter Reduction
- % Stenosis = (1 - residual/original)x100
- % Stenosis = (1 - residual/distal)x100
-
Cross Sectional Area Reduction
- % Stenosis = (1 - residual^2/original^2)x100
- % Stenosis = (1 - residual1 x residual2 / original1 x original2)x100
-
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
-
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
-
Color flow is based on...
Frequency shift, not velocity
-
Bluth and UW Criteria
Residual/Original
-
ACAS and NASCET Criteria
Residual/Distal
-
ACAS = Asymptomatic Carotid Atherosclerosis Study
Carotid Endarterectomy (CEA) in good risk patients with ICA asymptomatic stenosis of 60-90%
-
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
-
Velocity measurement variability causes inaccurate doppler stenosis parameters...
Each ultrasound department should develop their own doppler parameters for identifying high-grade carotid stenoses
-
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
-
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
-
Post stenotic evaluation
- Severity of post stenotic turbulence is proportionate to severity of the luminal narrowing
- Greater stenosis, greater spectral broadening
- 70%+ very turbulent
-
Based on ACAS (UW)
- ICA stenosis 60-90%
- PSV > 260 cm/sec and EDV > 70 cm/sec
-
Based on NASCET (Bluth)
- ICA stenosis 70-99%
- PSV > 325 cm/sec or ICA/CCA ratio > 4.0
-
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
-
Reversal of flow in vertebrals = Subclavian steal
- Normal
- Hesitating - perform reactive hyperemia
- Alternating - perform reactive hyperemia
- Reversed - full transition
-
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
-
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
-
UW: C - Moderate [16-49%] Sample Volume: ICA
- Systolic peak < 4.0 kHz orr 125 cm/sec
- Spectral broadening throughout systole
- No window
-
UW: D - Moderately Severe [50-79%] ICA
- Systolic peak > 4.0 kHz or 125 cm/sec
- Marked spectral broadening
- Increased diastolic flow
-
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
-
UW: E - Occlusion CCA ICA
- Flow to zero or reversed
- No signal
-
Normal CCA contour
First zero slope after systole is below midslope
-
Abnormal CCA contour
First zero slope after systole is above midslope
-
Bluth: Systolic Velocity Ratio
- (VICA/VCCA) > 1.8 ... 60%
- (VICA/VCCA) > 3.7 ... 80%
-
Bluth: Diastolic Velocity Ratio
- (VICA/VCCA) > 2.4 ... 60%
- (VICA/VCCA) > 5.5 ... 80%
-
Lesion
to hurt, loss of function of a part
-
When plaque is found in the ICA...
Patient should be seen annually
-
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
-
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
-
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
-
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
-
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
-
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)
-
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
-
Intracranial AVMs
- Symptoms vary with location and extent
- Focal epileptic seizures
- Hemiparesis
- Aphasia
- Amnesia
- Bruit
-
Cavernous Sinus AVM Symptoms
- Glaucoma
- Diplopia
- Headache
- Bruit (through eye)
- Surgery may not be possible
-
Characteristics of AV Extracranialy
- Pulsating mass
- Port wine birthmark - increase in skin temp
- Venous engorgement
- Pain and swelling
- Disfigurement
-
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
-
Treatment of AV Communications
- Possible brain surgery - location, size, condition of AVM
- Endovascular microembolization - coils, embolic therapy
-
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
-
Carotid Body Tumor - Group 1
Consists of relatively small tumors, which are minimally attached to the carotid vessels - surgical excision is not difficult
-
Carotid Body Tumor - Group 2
Tumors are larger, with moderate attachments. These tumors may require a temporary intraluminal carotid shunt during surgery
-
Carotid Body Tumor - Group 3
Tumors are very large neoplasms that encase the carotid arteries and often require arterial resection and grafting
-
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
-
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
-
Symptoms of Subclavian Steal
- Vertigo
- Limb paresis
- Visual disturbances
- Ataxia
- Syncope
- UE limb claudication
-
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
-
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
-
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
-
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
-
Subclavian Steal Symptoms
- Syncope
- Dysphasia
- Ataxia
- Dysarthria
- Facial sensory problems
- Claudication
- Muscle atrophy
- Skin changes
- Pain at rest
-
FMD
- Most common in renal arteries
- Found affecting ICA
- Known as string of beads
-
FMD Variants
- Intimal fibroplasia
- Medial hyperplasia
- Medial fibroplasia - most common
- Perimedial dysplasia
-
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
-
FMD Patients
- Female most common - mid adult age
- May be for estrogen
- May be caused by stress on ICA with poor medial blood
-
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
-
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
-
Carotid Artery Aneurysm
- Rare!
- Two types: Fusiform or Saccular
- Saccular is most common: at biurcation bilaterally
-
Aneurysm Symptoms
- Pulsating mass in neck
- Bruit
- May see bulge in neck
- Pain over area
- Cerebral ischemia may result, distal emboli
- Compression adjacent
-
Aneurysm - Differential Diagnosis
- Carotid Body Tumor
- Peritonsillar abscess
- Lymph node or tumor
- TORTUOUS VESSELS
- Treatment = surgery
-
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)
-
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
-
Tortuosity and Coils
- More common than kink
- Usually bilateral
- May be congenital
- May worsen with age
- Benign condition
- No treatment necessary
-
Interpretation of Moderate
- 50%
- Slight increase in spectral
- Disease is present
- Patient may be
- Need follow up at
-
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%)
-
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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