Ch. 7 Vascular Flashcards
What are the indications for an extracranial duplex exam
asymptomatic neck bruit TIAs stroke screening for surgery f/u after a stent ot carotid endarterectomy
How many bruits are related to high grade stenosis
1/3
What is an emboli
piece of plaque that breaks off
Neurological deficits that occur intermittently, lasting from several minutes to a few hours
TIA
When do symptoms for TIA resolve
within 24 hours
Fixed or permanent neurologic deficits
CVA or completed stroke
Neurological deficits that last between 24 and 72 hours
Reversible Ischemic neurological deficit (RIND)
Symptoms of Carotid Artery Lesions
paralysis
paresthesia on one side (opposite side of affected)
Dysphasia/aphasia
Amaurosis fugax
What is paralysis
focal weakness
What is paesthesia
numbness usually on one side of the body
What is dysphasia or aphasia
difficulty speaking
What is Amaurosis fugax
(same side as responsible carotid lesion) is a TIA of the eye that produces blindness “shade” being pulled down over one eye
Symptoms of vertebrobasilar Insufficiency
doziness
diplopia
ataxia
What is diplopia
double vision
What is ataxia
loss of full control of bodily movement
What does the physical exam require
bilateral blood pressures
palpation of pulses for strength and symmetry
auscultation for bruits
What transducer and frequency is used for this exam
linear 7-14MHz
Vessels should be evaluated in both transverse and longitudinal planes and with
b-mode imaging
color
spectral doppler
A mobile appearing white line echo in the CCA is most likely
reverberation artifact from the IJV
What does speckling indicate
bruit
What is pulsed wave spectral doppler used for
measure flow velocities
document waveform contours
Differences between the ICA and ECA
ECA has multiple branches /
ECA will oscillate with “temporal tap” /
ICA is larger /
ICA has a low resistance wave form
Where do you perform the “temporal tap”
superficial temporal artery anterior to the ear
The ECA spectral waveform will have a
high resistance waveform and low diastolic component
How does the ICA typically lay in relation to the ICA
posterior
ICA has a
low resistance waveform and high diastolic
Where is flow reversal located in the bulb
along outer wall of bulb
What indicates normal flow within the bulb
yin yang sign
Is velocity measurement needed on bulb
no
Documented for flow separation in bulb:
flow reversal
yin yang sign
Sweeo doppler sample volume from
CCA into proximal ICA
What is PSV
peak systolic velocity
What is EDV
end diastolic velocity
What does isonate mean
to image with ultrasound
Where do you place the transducer to evaluate the vertebral artery
anteromedial aspect of midneck on long axis
Where do you want to obtain doppler signal for subclavian artery
as far proximal as possible
What are a few pitfalls
vessels high/low in the neck /
patients with thick short necks /
beam steering and angle correction with different transducers
Normal B-Mode characteristics
smooth vessel walls /
intima media clearly visible /
lumen is anechoic
Where does plaque most commonly occur
CCA bifurcation
What are the early stages of plaque
appears as thickened areas of intima media layers /
fibrous cap may form between plaque and lumen
How is plaque usually classified
smooth, irregular, homogeneous, heterogeneous
What term is discouraged to use by a sonographer
ulcerated because it is diagnostic
What is homogeneous plaque
uniform appearance and low echogenicity (high lipid content)
What is heterogeneous plaque
mixed echogenicity (fatty material and calcium)
What are some intraluminal defects identified by b-mode imaging
arterial dissection
carotid artery thrombosis
iatrogenic injury
What is iatrogenic injury
any adverse condition that is induced by a healthcare provider
What is arterial dissection
separation of layers that creates a second/false lumen
What is crucial with arterial dissection
to differentiate a dissection from an internal jugular vein wall artifact (use multiple views)
Signs of arterial dissection (CCA)
absence “yin yang” color flow pattern in transverse /
absence “wall thump” in doppler waveform /
may still see a uniform doppler waveform
What dpes spectral doppler do
provides the most reliable means for assessing vessel patency and classifying degree of stenosis
Doppler waveform contour is related to
cardiac output
vessel compliance
peripheral resistance (status of distal vascular bed)
Normal doppler waveform contour (CCA, ICA, ECA)
brisk systolic acceleration
sharp systolic peak
clear spectral waveform
On spectral doppler, ICA has
highest diastolic velocities
lowest peripheral resistance
On spectral doppler, ECA has
lowest diastolic velocities
highest peripheral resistance
On spectral doppler, CCA has
intermediate diastolic velocities
characteristics of both ICA and ECA
What do bulb baroreceptors to
assist in blood pressure control
what do bulb chemoreceptors do
involved in control of respiratory rate
Carotid bulb doppler waveform
normal flow separation along outer wall /
more laminar flow near flow divider /
absence of flow reversal can be considered abnormal
What happens as plaque starts to develop in the bulb
it can fill the bulb, reducing flow separation
Abnormal doppler waveform contour distal to stenosis
decreased flow velocity
delayed acceleration
rounded peak
“tardus-parvus”
What is “tardus-parvus”
low velocity flow with delayed acceleration
In an abnormal doppler waveform contour, spectral broadening generally represents
turbulent flow
In abnormal doppler waveform contour, proximal to stenosis, with very significant stenosis
proximal waveform will display a more high resistance pattern (decreased or absent diastolic flow)
What is a steal waveform contour
where one vascular bed draws blood away or steals from another
Degree of steal depends on
severity of stenosis
resistance offered by the venous downstream vascular beds
What is a latent steal
flow that is beginning to show signs of reversal but not completely retrograde
Waveform characteristics of a hesitant waveform
antegrade flow with deep flow reversal notch /
alternating or bilateral
Hesitant doppler waveform contour sign
vertebral bunny sign
What is a complete steal
complete retrograde flow of vessel involved
What is string sign
blunted, resistive waveform that precede complete occlusion
Where is string sign most commonly found
ICA
How to detect string sign
use low scale and high gain doppler settings /
use power doppler to evaluate distal flow
Appearance of distal ICA stenosis or occlusion
decreased diastolic flow /
high resistance flow pattern indicates severe stenosis or occlusion distal to the segment evaluated /
blunted appearance
High resistance flow pattern indicates severe stenosis or occlusion ______ to the segment evaluated
distal
ECA stenosis _____ tend to involve origin and proximal segments
lesions
ECA stenosis associated with
focal velocity increase
post-stenotic turbulence
dampened distal waveform
In ECA stenosis, watch for _____ in velocity as a result of collateralization
diffuse increase
CCA stenosis can occur in the
proximal, mid or distal segments
Significant stenosis in CCA is associated with
focal velocity increases
poststenotic turbulence
dampened distal waveforms in both the ICA and ECA
May result in retrograde ECA to supply ICA
choke lesion
Aortic valve and root stenosis will generate
symmetrically abnormal doppler waveform contour in the bilateral carotid systems
In aortic valve or root stenosis, dampened waveforms are ______ carotid artery systems
throughout both
AV or RS may also have _____ brachial systolic pressures
bilateral low
Brachiocephalic stenosis will _____ affect the right carotid system
only
Special considerations for AV or RS
low cardiac output or poor EF / aortic valvular disease / hypertrophic obstructive cardiomyopathy / arrhythmias / cardiac assist devices
What is the primary criterion for classification of stenosis severity
doppler flow velocity
doppler flow velocity depends on
correct doppler angle 60 degrees or less and parallel to vessel wall
doppler flow velocity may require doppler beam
steering or “heel toe” to get proper alignment
Pulsed wave doppler sample volume should be
“swept” through all vessels
Criteria for classification of disease has validated for the
ICA only
Criteria for classification of disease was developed by comparing duplex results with
“gold standard” imaging modalities (angiography)
Classification for disease for CCA and ECA stenosis criteria are
focal velocity increase
poststenotic turbulence
distal waveform changes
Changes in CCA and ECA for stenosis correlate with a
<50% stenosis in these vessels
Smooth, single color in the low to medium tone range indicates
laminar flow
Aliasing occurs with
higher flow velocities
______ produces a “mosaic” color doppler pattern
turbulent flow
Always use ______ waveforms to classify severity of disease
pulsed wave spectral doppler
Power doppler displays flow based on _____ rather than ______ shift
amplitude
frequency
_______ has no direction information and is independent of angle
power doppler
Power doppler is extremely helpful in detecting ______ velocities such as “string sign”
extremely low flow
What is helpful with power doppler
high color gain
low color scale (PRF)
low wall filter
Proximal vertebral artery usually evaluated during routine
carotid duplex scan
Normal vertebral artery flow has same pattern as
ICA
Normal flow in vertebra artery is
low resistance antegrade brisk systolic acceleration sharp peak high diastolic flow
PROXIMAL vertebral artery stenosis will produce
abnormal antegrade dampened waveforms distally with delayed acceleration and rounded peaks
Proximal vertebral artery stenosis occurs at origin from
subclavian artery
What waveforms indicate DISTAL stenosis or occlusion
resistive or blunted
Hemodynamically significant stenosis in the proximal subclavian artery causes changes to
vertebral artery flow
Subclavian stenosis results in ______ decrease on affected side more than ______ lower than contralateral arm
brachial blood pressure
15 mmHg
Subclavian stenosis will show
elevated flow velocity with post stenotic turbulence /
abnormal vertebral artery waveform contour
What are the steps to vertebral artery flow changes as obstruction progresses
- normal antegrade flow
- antegrade with deep notch mid cycle
- alternating or bidirectional flow
- complete reversal fully retrograded flow
What is reactive hyperemia
proactive test used to augment a subclavian steal from “latent” to “complete”
