Chapter 7: The Extracranial Duplex Ultrasound Examination Flashcards
an abnormal “blowing” or “swishing” sound heard with a stethoscope while auscultating over an artery, such as the carotid. The sound results from vibrations that are transmitted through the tissues when blood flows through a stenotic artery.
bruit
A slight dilation involving variable portions of the distal common and proximal internal carotid arteries, often including the origin of the external carotid artery. This is where the baroreceptors assisting in reflex blood pressure control are located.
carotid bulb
Most commonly defined as the angle between the line of the Doppler ultrasound beam emitted by the transducer and the arterial wall (also called the “angle of insonation”). This is a key variable in the Doppler equation used to calculate flow velocity.
Doppler angle
The location along the ultrasound beam where a pulsed Doppler detects flow. The size and the depth of the sample volume can be adjusted by the examiner to allow evaluation of flow at any site in the B-mode image.
sample volume
A signal processing technique that displays the complete frequency and amplitude content of the Doppler flow signal. The spectral information is usually presented as waveforms with frequency (converted to a velocity scale) on the vertical axis, time on the horizontal axis, and amplitude indicated by a grayscale.
spectral analysis
An increase in the “width” of the spectral waveform (frequency band) or “filling in” of the normally clear area under the systolic peak. This represents turbulent blood flow associated with arterial lesions.
spectral broadening
An episode of stroke-like neurologic symptoms that typically lasts for a few minutes to several hours and then resolves completely. This is caused by a temporary interruption of the blood supply to the brain in the distribution of a cerbral artery.
transient ischemic attack (TIA)
Normal ICA PSV
<125 cm/s
Extensive plaque, often with acoustic shadowing due to calcification
PSV >125 cm/s and EDV > 140 cm/s
Severe (80-99%) ICA stenosis
Retrograde of “hesitant” flow in the ipsilateral vertebral artery
subclavian steal
brachial systolic pressure gradient >15 mmHg
Subclavian steal
minimal or no spectral broadening; flow separation present in the carotid bulb
Normal ICA
spectral broadening during deceleration phase of systole only
1% - 15% occlusion
spectral broading throughout systole; plaque
16-40% occlusion
mark spectral broadening; plaque
80-90% occlusion
No flow signal in the ICA; decreased or absent diastolic flow in the ipsilateral CCA; plaque or thrombosis in the ICA lumen; diffusely increased PSV in contralateral carotid system
100% occlusion
Primary goal of noninvasive testing for extracranial cerebrovascular disease
identify patients who are risk for stroke due to athersclerotic plaque
Secondary goal on nonvasive testing for extracranial cerebrovascular disease
document progressive disease in patients already known to be at risk or recurrent stenosis after intervention
Major indications Carotid exam
asymptomatic neck bruit
hemispheric cerebral or occular transient ischemic attacks
history of stroke
screening before major peripheral vascular
Only about ___ of bruits are related to high-grade internal carotid stenoses
1/3
sometimes referred to as a “mini stroke?
TIA
characterized by
focal weakness
numbness
aphasia
TIA
also known as cerebrovascular accident
stroke
provide best image resolution; most options for Doppler angle correction
linear array transducer 12-3MHz
Scale should be set in the range of ______ cm/s.
20-40
typically located anterior and medial to ICA
ECA
can be identified as the artery with multiple branches beyond carotid bifurcation
ECA
visible as a thin gray-white line on innermost part of wall
intima-media layer
Plaque most commonly forms at _______, ______, ______, and ______
common carotid bifurcation
distal CCA
proximal ICA
proximal ECA
uniform in appearance; often of relatively low echogenicity; correlates with high lipid content and presence of fibro fatty tissue; smooth appearing fibrous cap
homogeneous plaque
may be composed of fatty material and areas of calcium that tend to cause brighter echoes and acoustic shadowing.
mixed echogenicity plaque
occurs when calcium attenuate the transmission of ultrasound
acoustic shadowing
can cause plague to become “unstable”; can expand, increasing both degree of stenosis and potential to produce emboli to brain; ulceration or rupture of fibrous cap
intraplaque hemorrhage
disruption of the intima with blood from the true lumen flowing between layers of vessel wall
intraluminal defects
referred to as arterial dissection
intraluminal defects
Where do spontaneous arterial dissections usually occur?
aortic root
most often related to progressive atherosclerotic plaque, cardiogenic emboli, trauma, or dissection
carotid artery thrombosis
any adverse patient condition that is induced inadvertently by a provider in course of diagnostic procedure or therapeutic intervention
iatrogenic injury
provide hemodynamic information for interpretation of flow changes proximal to, at, and distal to insonated location
Doppler Spectral
provides most reliable means for assessing vessel patency and classifying degree of stenosis
spectral Doppler
CCA, ICA, ECA Normal Doppler Waveform contour
rapid systolic upstroke
sharp systolic peak
clear spectral “window” under peak
supplies brain directly
lowest peripheral resistance
highest diastolic flow velocities with forward flow throughout cardiac cycle
ICA
relatively high resistance vascular bed; includes muscles of face and mouth; produces lower diastolic flow velocities; often results in a multiphasic waveform
ECA
takes on characteristics of both ICA and ECA; low resistance flow pattern with forward flow through cardiac cycle
CCA
____% of normal CCA flows through ICA
70
higher resistance flow pattern with forward flow throughout cardiac cycle
higher resistance flow pattern that reflects status of multiple vascular bed that it supplies: arm (high resistance), face (high resistance), brain (low resistance)
brachiocephalic artery
slight focal dilation in artery where baroreceptors assisting in reflex blood pressure control are located; typically involves origin and proximal segments of ICA, but dilated segment may also include distal CCA or origin of ECA
carotid sinus or carotid bulb
dictate that the flow pattern within a significant stenosis will be characterized by a high-velocity jet
hemodynamic principles
the situation where one vascular bed draws blood away or steals from another
steal waveform
flow that is beginning to show signs or reversal, not yet completely retrograde
latent steal
possess a deep flow reversal notch when flow pauses before progressing cephalad
hesistant steal
deep notch in Doppler waveform extends below baseline, with a portion of the flow being retrograde during part of the cardiac cycle
alternating or bidirectional
changing pressure gradients at origin of ipsilateral vertebral artery can alter ratio of antegrade to retrograde flow in the vertebral artery to the point when flow is entirely in retrograde direction
complete steal
characterized by low-velocity, somewhat resistive waveforms, pattern that proceeds complete occlusion of a vessel; most likely to be found in severely diseased ICA
“string sign” flow
tend to involve proximal and origin segments of ECA, associated with: focal velocity increase, postenotic turbulence, and dampened waveform distally
ECA stenosis
generate symmetrically abnormal Doppler arterial waveform contour in right and left carotids; brachial systolic pressures may also be symmetrically low
aortic valve or root stenosis
decreased pressure and waveform changes in right CCA and subclavian artery and their distal branches
Severe stenosis or occlusion of brachiocephalic artery
a severe distal ICA obstruction with continued patency of bifurcation
“choke” lesion
an unusual waveform with two prominent systolic peaks separated by a mid-systolic refraction
pulsus bisferiens
the angle between the line of the ultrasound beam and the arterial wall at site of PW Doppler sample volume
Doppler angle of insonation
obtained using an angle of insonation of 60 degrees or less
arterial velocity measurements
Carotid and vertebral systems are connect by ______ at the base of the brain.
circle of Willis
low resistance pattern; antegrade flow (toward the brain); rapid systolic acceleration; sharp peak and relatively high diastolic flow
vertebral artery
generally occur at origin of vessel from subclavian artery
vertebral artery stenosis
Normal PSV
30-50 cm/s
occurs with severe stenosis or occlusion of subclavian artery proximal to origin of vertebral artery; causes decreased pressure at origin of ipsilateral vertebral artery
subclavian steal
provocative noninvasive test that can be used to augment a subclavian steal from the latent or hesitant stages to complete stage
reactive hyperemia
produced by period of arterial occlusion; results in vasodilation and an increase in brachial systolic pressure gradient
tissue ischemia
What is the secondary goal of examination of the extracranial carotid artery system by duplex ultrasound?
to document progression of the disease
Which transducer is most commonly used to perform a duplex evaluation of the extracranial cerebrovascular system?
12-3Mhz linear array
A patient presents to the vascular lab for a carotid-vertebral duplex examination. Upon questioning, the patient reveals a 2 week history of intermittent blindness in the right eye. What would these symptoms indicate?
TIA
How should the patient’s head be positioned in order to expedite a carotid-vertebral duplex examination?
head rotated 45 degrees away from side being examined with a pillow under the shoulders
What is the most common technique used to identify the vertebral artery?
view the CCA and angle the transducer slightly posterior
When qualifying the appearance of plaque by ultrasound, the use of which of the following terms is discouraged owing to poor reliability?
a. homogeneous/heterogeneous
b. smooth/irregular
c. ulcerated
d. calcified
c
As plaque develops and fills the carotid bulb, what change can be expected in the Doppler waveform at theis level?
disappearance of normal flow separation
Which of the following will NOT result in symmetrical changes in the Doppler spectra?
a. aortive valve or root stenosis
b. brain death
c. subclavian steal
d. intra-aortic balloon pump
c
In a normally hemodynamically low-resistance system or vessel, such as the internal carotid and vertebral arteries, what will a change to high-resistance pattern suggest?
distal stenosis or occlusion
What is reactive hyperemia, a provocative maneuver used during the duplex examination of the extrancranial cerebrovascular, used to demonstrate?
a change from latent or partial to complete subclavian steal
Which of the following is NOT “sound” advice for sonographers who wish to prevent repetitive stress injuries while scanning?
a. be ambidextrious
b. arrange bed and equipment to be close to the patient
c. remain well hydrated during the day
d. avoid doing stretching exercises
d
Why do Doppler waveforms in the CCA display a contour suggestive of relatively low-resistance flow?
70% of its flow supplies the ICA
What type of flow is characterized by a blunted resistive waveform that often occurs as disease progresses to near occlusion?
string sign flowa
Which statement on power Doppler is FALSE?
a. it represents the amplitude of the Doppler signal instead of frequency shift
b. It depends on the angle of insonation
c. it does not give information about flow direction
d. it can detect low flow states
b
A patient presents to the vascular lab with a severe distal CCA obstruction; however, the internal carotid and external carotid artery remain patent. What is this lesion typically called?
choke lesion
During duplex evaluation of the internal carotid artery, peak systolic velocities are noted to be 532 cm/s and end diastolic velocities are 167 cm/s. According the University of Washington criteria, into what stenosis category would these findings fall?
80-99% stenosis
For subclavian steal syndrome or phenomenon to occur, where does a severe stenosis or an occlusion need to present?
the left subclavian artery or brachiocephalic artery proximal to the vertebral artery origin
Which of the follow would affect puled Doppler spectrum contour in all vessels of the extracranial cerebrovascular arterial system even when no disease is present?
a. low cardiac output
b. aortic root stenosis
c. intra-aortic balloon pump
d. all of the above
d
During duplex evaluation of the carotid artery system, velocities in the external carotid artery reached 250 cm/s, and turbulence was noted just after the area of increased velocty. What do these findings suggest?
> 50% stenosis
The primary goal of an examination of the extracranial cerebrovascular system by duplex ultrasound is to identify patients at risk for _____.
stroke
Approximately ____ of neck bruits are related to significant stenosis of the ICA.
1/3
Lesions or stenoses in the internal carotid arteries can be present without _____ symptoms.
neurologis
High-grade stenoses of the internal carotid arteries, as flow restricting lesions, are rarely the primary cause of neurologic symptoms because of ______.
collateral flow
Flow separation can be seen in the carotid bulb and will be represented by brief flow ____.
reversal
Transient symptoms manifested as a difficulty to speak are termed as ____.
aphasia
Neurologic deficits lasting between 24 and 72 hours are classified as _____.
RIND
(reversible ischemic neurologic deficit)
If significant flow turbulence is noted in the proximal right common carotid, it becomes imperative to examine the _____.
brachiocephalic artery
There are usually two recommended methods to distinguish the internal from the external carotid artery. In one method, one would perform _____ to demonstrate oscillations on the Doppler spectru,
temporal tap
The use of a curved or phased array transducer is recommended for the examination of the distal internal carotid arteries, particulary in patients with tortuous vessels, fibromuscular dysplasia, or vessels that are _____ than usual.
deeperI
In order to evaluate the subclavian artery, the transducer is placed in a(n) _______ orientation at the base of the neck
transverse
The internal featuresa of plaque found in the extracranial cerebrovascular system are usually related to the _____ of the plaque
echogenicity
Bleeding within a plaque underneath the fibrous cap (intraplaque hemorrhage) can cause the plaque to become ____.
unstable
Dissection of the intima, particular in common carotid arteries, could be confused with artifacts from the wall of ______.
internal jugular veins
______ injury is defined as any adverse patient condition that is induced inadvertently by a health care provider during a diagnostic procedure or intervention.
iatrogenic
“latent”, “hesitant”, “alternating”, and “complete” are terms usually describing the stages of ______.
steal phenomenon
The wavform contour distal to a significant stenosis is often referred to as a ______ pattern, characterized by damp, rounded waveform with decreased velocity and delayed acceleration
tardus parvus
In the presence of significant common carotid stenosis, the ICA/CCA ratio criteria are _____.
not valid
_____ Doppler is particularly helpful in detecting extremely low-flow velocities, including string sign flow.
power
According to the criteria developed by the University of Washington, ,the stenosis categories below the 50% threshold are differentiated from one another by the presence or absence of flow separation, the extent of spectral ______, and the amount of plaque visualized.
broadening
Symptoms of vertebrobasilar insufficiency include all of the following except:
a. ataxia
b. diplopia
c. dizziness
d. amaurosis fugax
d
What is the best method for evaluating an arterial segment for stenosis?
sweep through with spectral Doppler
Which of the following is a potential pitfall in performing a temporal tap maneuver?
a. visible oscillation occurs in the ECA and not in the ICA
b. performing a temporal tap in the presence of an ICA occlusion
c. oscillations may be transmitted within the ICA if the temportal artery is tapped too strongly
d. No oscillations will be generated if the temporal artery is inadequately tapped
a
What is the name of the artifact caused by heavily calcific plauqe?
acoustic shadowing
Neurologic defecits that occur intermittently, lasting from several minutes to a few hours, symptoms resolve within 24 hours
Transient Ischemic attack
fixed or permanent neurgolic defects
cerebrovascular accident
Neurologic defecits that last between 24 and 72 hours
reversible ischemic neurologic defecit
Carotid artery duplex evaluation generally includes examination of bilateral:
CCAs
ICAs
ECAs
vertebral arteries
subclavian arteries
Color Doppler should be used to identify:
areas of aliasing or mosaic flow patterns
speckling that could indicate color bruit
Pulsed wave spectral Doppler is used to”
measure flow velocities
document waveform contours
ECA spectral waveform will oscillate with _____.
temporal tap
ICA typically lies _____ to ECA
posterior
Plaque most often occurs at the _____.
CCA bifurcation
_____ may form between plaque and lumen.
fibrous cap
By ultasound plaque is usually classified as _____ vs. ______ or ______ vs. _______.
smooth
irregular
homogeneous
heterogeneous
Provides the most reliable means for assessing vessel patency and classifying degree of stenosis
Spectral Doppler
Doppler waveform is related to:
cardiac output
vessel compliance
status of distal vascular bed
distal vascular bed:
ciricle of Willis
ICA has _____ diastolic velocities and _____ peripheral resistance.
highest
lowest
ECA has _____ diastolic velocities and _____ peripheral resistance.
lowest
highest
slight focal dilation in the carotid artery
carotid bulb
contains baroreceptors that assist in blood pressure control
carotid bulb
a situation where one vascular bed draws blood away or steals from another
steal
Degree of steal depends on:
Severity of stenosis
resistance offered by the various downstream vascular beds
flow that is beginnings to show signs of reversal but not completely retrograde
waveform characteristics can be:
hesitant (deep flow reversal notch)
alternating or bidirectional
latent steal
complete retrograde flow of vessel involved
complete steal
Associated with the following findings in extracranial ICA:
decreased diastolic flow or resistive compnent
overal “blunted” appearing waveform
Distal ICA stenosis or occlusion
Associated with:
focal velocity increase
poststenotic turbulence
damplened distal waveform
ECA stenosis
_____ may result in retrograde ECA to supply ICA
Choke lesion
Will generate symmetrically abnormal Doppler wavefor,m contouir in the bilateral carotid systems; may also cause bilateral low brachial systolic pressures
aorti valve or root stenosis
Brachiocephalic stenosis will only affect the ___ carotid system
right
PSV > 230 cm/s
ICA/CCA ratio >4.0
> 70% stenosis
low resistance
antegrade flow throughout cardiac cycle
brisk systolic acceleration, sharp peak, and relatively high diastolic flow
vertebral artery flow
Symptoms of vertebrobasilar insufficiency include all of the following except:
a. dizziness
b. ataxia
c. amaurosis fugax
d. diplopia
c
What is the best method for evaluating an arterial segment for stenosis?
sweep through with spectral Doppler
Which of the following is not a potential pitfall in performing a temporal tap maneuver?
a. Performing a temporal tap in the presence of an ICA occlusion
b. Visible oscillation occurs in the ECA and not in the ICA
c. Oscillations may be transmitted within the ICA if the temporal artery is tapped too strongly
d. No oscillations will be generated if the temporal artery is inadequately tapped
b
What is the name of the artifact caused by heavily calcific plaque?
acoustic shadowing
Which of the following is true about normal ICA flow?
a. low resistance flow with low diastolic flow component
b. high resistance flow with low diastolic flow componenet
c. high restistance flow with high diastolic flow compenent
d. low resistance flow with high diastolic flow component
d
What crucial element should be documented when confirming string that sign flow is present (and the ICA is not completely occluded)?
presence of Doppler flow in the mid/distal ICA
What is meant by the term “choke lesion”?
severe stenosis or occlusion of the CCA
Which of the following would invalidate the ICA/CCA ratio (NASCET method)?
a. severe stenosis of the ECA
b. Severe stenosis of the ascending aorta
c. severe stenosis of the CCA
d. Severe stenosis of the contralateral ICA
c
What does spectral broadening in the Doppler waveform generally represent?
turbulent flow
Flow separation is:
a. only observed at a flow reducing carotid stenosis
b. a term referring to retrograde flow in the ECA, which feeds the ICA
c. observed in the CCA in patients with aortic insufficiency
d. often observed at the carotid bulb and appears as a small area of flow reversal
d
The normal position of the vertebral arteries is:
passing through the transverse processes of the cervical vertebrae
The characterization of an ulcerative plaque is best done with:
a pathologic specimen at time of surgery
Which of the following statements about the ECA is not true?
a. it supplies a low resistance bed
b. it can demonstrate a multiphasic waveform similar to a peripheral artery
c. it demonstrates lower diastolic velocities when compared with the ICA
d. It supplies the muscles of the face and mouth
a
In a patient with reversed right vertebral artery flow, the possible cause of the steal can be:
a stenosis in the brachiocephalic artery
The concensus criteria use which two values as secondary parameters for ICA disease classification?
The ICA end-diastolic velocity (EDV) and the ICA/CCA peak systolic velocity ratio
The main advantage of power Doppler imaging is:
the ability to detect low flow startes
Which of the following statements correctly identifies the calculation of the ICA/CCA peak systolic velocity ratio?
a. Use the highest PSV from the stenotic site for the ICA and the PSV from the normal mid to distal CCA
b. use hte highest PSV from the stenotic site for the ICA and the PSV from the proximal CCA
c. Use the highest PSV from the ICA and the highest PSV from the CCA
d. Use only the proximal ICA PSV and the PSV from the normal mid to distal CCA
a
Gold standard techniques used to validate carotid ultrasound criteria include all of the following except:
a. CTA
b. MRA
c. Contrast arteriography
d. MRI
d
The transducer maneuver used to adjust vessel insonation to help create an angle of 60 degrees or less is called:
toe-heel maneuver
Cardiac assist devices used in patients with heart failure can have what affect on carotid artery signals?
the contour is affected such that the pattern of arterial flow is unrecognizable
