Carotid Grading Flashcards
Critical stenosis is a (3)
Hemodynamically significant reduction in volume, pressure and flow
What % of the cross-sectional area must be encroached upon before there’s a reduction in distal pressure & flow in the AORTA versus the carotid
Aorta: 90% reduction cross sectional area
Carotid: 70-90% reduction
Plaque morphology: what does homogenous vs heterogenous vs calcified vs ulcerated suggest
Homogenous - acute
Heterogenous - longer
Calcified - chronic
Ulcerated - a piece broken off
T/F - power Doppler does not show aliasing however it helps delineate low flow
True
How do you adjust parameters to demonstrate low flow? (2)
Lower velocity scale & colour gain
Stenosic zone SOUND
High pitched whistling (higher velocity)
Post-stenotic turbulence SOUND
Garbled sound
Distal stenosis SOUND
Low pitch, weaker amplitude
Complete occlusion SOUND
Thumping
What is the normal carotid intima media thickness (CMIT) measure?
<0.9 mm
What do you document when a stenosis is found (4)
1- Proximal stenosis sample
2- Within stenosis: measure PSV & EDV (highest velocity recorded 2-3 times).
3- After stenosis: document post-stenotic turbulence
4- Distal tardus parvus waveform
What is the PSV ratio measurement?
What does the ratio indicate as it increases?
When is this useful?
- PSV stenosis/PSV ICA
- The higher the ratio, the greater the stenosis (directly proportional relationship)
- Useful when velocities are globally low (i.e. decreased heart function)
A MILD stenosis: ____% diameter reduction
Mild: 20% diameter reduction
A MODERATE stenosis: ____% diameter reduction
MODERATE: 20-50% diameter reduction
A MODERATELY SEVERE stenosis: ___% diameter reduction
MODERATELY SEVERE: 50-80%
A SEVERE stenosis: ___% diameter reduction
SEVERE: >80% diameter reduction
Total occlusion is
No residual lumen to measure
Difference between calculating DIAMETER reduction vs. AREA reduction
Diameter:
longitudinal view + hemeodynamically significant lesions >50% diameter reduction
Area:
Transverse view + hemodynamically significant lesions >75% area reduction
What is the FORMULA for calculating % stenosis for area/diameter reduction?
= 1 - (residual/original) * 100
Systolic Acceleration Time (AT) or
RISE TIME is the
Onset of systole to peak systole (ms)
The rise time in the renal arteries should be less than ____
70 ms
NASCET Criteria:
<15% stenosis traits
Deceleration spectral broadening
< 125 cm/s PSV
NASCET Criteria:
16-49% ICA Stenosis traits
Pansystolic spectral broadening
<125 cm/s PSV
NASCET criteria:
50-69% stenosis
Pansystolic spectral broadening PSV >125 cm/s EDV <110 cm/s OR ICA/CCA PSV ratio between 2-4
NASCET criteria
70-79% stenosis
Pansystolic spectral broadening PSV >270 cm/s OR EDV >110 cm/s OR ICA/CCA ratio >4
NASCET Criteria
80-99% stenosis
EDV > 140 cm/s
Patient HISTORY (6)
Previous stroke Smoker Elevated BP Hyperlipidemia Diabetic Family Hx of any above
INDICATIONS (7)
Headaches Bruit Present stroke TIA Vertigo/dizziness A autos is fagax Limb weakness
When are carotid BRUITS most COMMON? When are they most SEVERE?
Common: With increasing stenosis and maximal at 70-90% stenosis
Severe: If pt has ipsilateral bruit, diabetes, or previous TIA
*DIFFERENTIAL DIAGNOSIS of a carotid bruit (7)
- Murmur radiating from stenosis ao valve
- ECA disease
- Intraluminal turbulence ICA
- Arteriovenous malformations
- External compression from thoracic outlet syndrome
- Scarring due to neck surgery
- Tumour
If the ICA/CCA ratio is 2 or more, then what 3 things occur?
There is a hemodynamically significant stenosis, meaning
1- the velocity doubles from CCA to ICA
2- the PSV of the ICA is > 125 cm/s
3- the ratio is 2 or more
How do you measure the ICA/PSV ratio?
Proximal ICA PSV/Distal CCA PSV
What is a CEA?
Carotid endarterectomy
A surgical procedure that removes plaque / blockage in lining of artery
*When is a CEA recommended?
If the patient is symptomatic and >70% narrowing of artery
How is calcified plaque delineated on the technical impression
Xxxxxx
What is TRICKLE FLOW also referred to as?
Pre-occlusive flow
With trickle flow, how would you adjust the parameters? (3)
Decrease PRF
Increase colour gain
Increase sample volume size to lumen width
COLLATERAL flow examples (3)
1- OA direction in setting of high grade/complete occlusion of ICA
2- reversed VA flow and brachial artery systolic pressures in setting of SSS
3- Reversed ECA flow in setting of CCA occlusion
Document changes in flow patters if the ICA is occluded (5)
1- Lower resistant with high flow “internalization” (because flow is now going into the ICA)
2- Post stenotic turbulence to stenosis (PST)
3- turbulent prox CCA flow in setting of INN A or LT SCA stenosis
4- Tardus parvus waveform distal to high grade stenosis
5- High resistant CCA prox to ICA stenosis
When does externalization of the CCA happen?
Occlusion ICA, retrograde flow in stump of ICA, absence of flow in the ICA and beyond
You should always include image of prox ICA demonstrating colour outline of _____ plaque
Soft plaque
The term for a longer area of calcified plaque
How does this affect flow versus a shorter area of plaque?
Sessile
Is angle correct necessary for the opthalmic artery?
No, only the direction of flow is important
When do you use a straight colour box? (2)
Tortuous vessels
Imaging vessel in TRV
POST STENOTIC TURBULENCE waveform
Loss of sharp upstroke
Jagged peak
Flow above and below the baseline simultaneously
When you’re assessing OA, what parameters do you change? (2)
Lower PRF
Remove angle correct
OA reversed flow suggests what (2)
ICA occluded or high grade stenosis
Normally ICA feeds the OA, but if it’s occluded, then ECA will feed OA
What plaques are the most dangerous and why?
Hypo/echolucent - most likely to break off
