Unit 10: Abnormal Carotid Doppler Flashcards
What is used as the primary means of indicating % of stenosis?
Doppler.
What is the purpose of a carotid duplex exam PW Doppler?
- Identify artery
- Identify hemodynamically significant obstructions
- Grade severity of stenosis
- Document velocity changes across time
- Document velocity changes across locations in the artery.
What is the doppler flow patterns PRE-STENOSIS?
- Probably normal.
- High resistance ONLY for very tight distal obstructions or occlusions.
No diastolic flow in the CCA indicates what?
An ICA occlusion.
No diastolic flow in proximal ICA indicates what?
A distal ICA occlusion.
also known as “carotid siphon occlusion”
What is the doppler signal like AT STENOSIS?
- Abnormal
- As stenosis increases:
- Higher velocities caused increase change in frequencies.
- If stenosis is >50%, psv is atleast 2x pre-stenosis
- Spectral broadening which indicates non-laminar flow.
- May have reversed flow under peak.
- Increased velocity extends into post-stenotic turbulence.
How does the velocity differ with a hemodynamically signficant stenosis?
Velocity increases dramatically at 50% diameter stenosis or 75% area stenosis.
How should you measure velocities at a stenosis?
Must scroll SV through entire stenosis to fid the highest velocity center stream.
What is the typical velocity found in a stenosis >50%
Typically >125 cm/sec.
What is VITAL for accurate grading of stenosis ?
- Find and report the highest velocity center stream in the stenosis.
- Maintain a true angle with cursor parallel to the walls.
- Angle 60 degrees or less.
- Update frequently to be sure to maintain accurate location of SV and angle.
What are the doppler flow patterns post-stenosis?
- Post-stenotic turbulence.
- Severe spectral broadening
- Often reversed flow under systolic peak.
- Feathered downslope
- High PSV may continue at first and decrease distally.
What should you document in a stenosis?
The highest psv and edv in the stenosis.
How many samples should you take in a stenosis for accurate grading?
2-3 samples.
What documentation is need to make a diagnosis of a stenosis?
- Must show psv/edv/waveform at pre-stenosis and post-stenosis
- Must calculate the ICA/CCA ratio.
- Measure B-mode image in long and transverse
- Identify all arteries correctly. (include FD in all images that include distal CCA)
If a stenosis is graded 0-19% with a psv <125, what kind of waveform will it yield?
No spectral broadening.
If a stenosis is graded 20-49% with a psv <125, what type of waveform will it yield?
Some spectral broadening.
If a stenosis is graded 50-79% with a psv >125 and a edv of >140, will yield what type of waveform?
Turbulence.
A stenosis is graded 80-99% with a psv >125 and edv >140, what type of waveform would it yield?
Marked turbulence.
What does a ICA/CCA ratio of >2.0 signify?
>50% diameter stenosis.
What does a ICA/CCA ratio of >4.0 signify?
70% diameter stenosis.
T/F:
We don’t identify stenosis in the vertebral arteries.
True.
What do we check in the vertebral arteries?
Check for the PRESENCE of flow.
What must you be careful of when examining the vertebral arteries?
Check carefully for flow DIRECTION.
What does parvus tardus indicate in a vertebral artery waveform?
It indicates a proximal obstruction.
What does no edv with good visualization of vertebral indicate in a waveform?
Distal obstrucction, probable occlusion.
What do you need in order to state a possible occlusion of the vertebral artery?
Need a clear image.
What are To and Fro flow patterns in the vertebral artery due to?
Proximal and distal pressure changes during the cardiac cycle.
What can you use to document complete reverse flow on exercise?
Post-occlusive reactive hyperemia (PORH)
How do you preform a PORH exam?
- Place a pressure cuff on the arm of the affected side.
- Inflate to 30 mmHg above brachial pressure
- Hold for 3 minutes
- Deflate and check vertebral flow direction
- Pendulum flow may change to all reversed flow.
What does a biphasic, monophasic, or extensive turbulence indicate in the SCA?
It suggests a proximal obstruction.
What should you do to prove a subclavian obstruction ?
Take brachial pressure bilaterally.
Must be >20 mmHg difference to be signifcant.
The lowest side has the obstruction.
What should you check in order to identify subclavian steal?
Check vertebral flow.
What is the diagnosis criteria of SSS?
- Reversed vertebral flow
- BP difference >20 mmHg OR abnormal SCA doppler same side.
