Quiz 1 Flashcards
what is a critical stenosis?
narrowing of the arterial lumen resulting in a hemodynamically significant reduction in volume, pressure, and flow
In the AORTA, how much of a cross sectional area must be encroached upon before there is a reduction in pressure and flow distally?
90%
in SMALLER VESSELS (such as carotid arteries) how much of a cross sectional area must be encroached upon before there is a reduction in pressure and flow distally?
70-90%
what is a reliable sonographic sign of a high grade stenosis?
colour aliasing
what happens to velocity as flow enters a stenotic area?
velocity of the colour flow increases to a point beyond primary settings
do we image aliasing?
yes
when is the only time we adjust velocity scale and colour gain?
if flow is not seen in an area of obvious plaque. we do this to show low flow
what helps to show low flow states?
power doppler
what does stenotic area sound like?
sounds will become high pitched or “whistling”
what is the sound of the waveform as you exit the stenotic zone and encounter post stenotic turbulence?
garbled
what does the flow sound like distal to a stenosis?
sounds becomes more low pitched again but its weaker in amplitude
what sound will be make when there is a complete occlusion?
thumping sound
what is the CIMT normal thickness?
<0.9mm
what are the 3 steps when measuring PSV within a stenosis?
- sample just prox to stenosis
- record the highest velocity within a stenosis more than once
- document post stenotic turbulence just distal to stenosis
what should the angle correct be when measuring the PSV within a stenosis?
should be parallel to vessel walls and 60 degrees
what do you do with sample volume inside a stenosis?
- move SV through narrowed area slowly using track ball
- listen for a high pitched sound
- look for colour aliasing
what sample sites WITHIN a stenotic zone must you document?
2-3 similar velocities with PSV and EDV measurments
what sample sites must you document with a stenosis?
- prior to stenosis
- within stenosis
- PST after stenosis
- distal tardus parvus waveform
what do we compare in a ratio meausurments?
flow velocity within a stenosis to the flow velocity in a more proximal stenosis
when is the ratio for stenosis not useful?
only useful when there is no stenosis or disease in the proximal setting
the higher the ratio______________
the greater the stenosis (directly proportional)
when are ratio measurments useful?
decreased heart function where the velocities are globally low throughout
diameter reduction mild stenosis
<20% diameter reduction
diameter reduction moderate stenosis
20-50% diameter reduction
diameter reducton critical (moderatley severe) stenosis
50-80% diameter reduction
diameter reduction severe stenosis
> 80% diameter reduction
diameter reduction total occlusion
no residual lumen to measure
what is diameter reduction measurement comparable to?
PSV measurments in a stenosis
what plane do we calculate diameter reduction?
SAG (longitudinal)
where are disatance measurments taken?
original lumen and the residual lumen
what is the formula for determining diameter and area reduction?
1-(residual/original) X 100
hemodynamically significant lesions are those with what percent in DIAMETER?
> 50 diameter reduction
what plane do we calculate area reduction?
TRV with the stenotic area
where are area measurments taken?
original (distal or prox) and the residual lumen
hemodynamically significant lesions are those with what percent with AREA?
> 75%
what is acceleration time (rise time)?
time elapsed from onset of systole to peak systole
where is significant delay to peak systole obtained?
in a waveform distal to a significant stenosis as in tardus parvus waveform
when is flow velocity slower?
when blood must move around an area of blockage through high resistant collateral pathways
when is systolic rise time extended?
when blood must move around an area of blockage through high resistant collateral pathways
where do we place calipers for acceleraton time?
calculated by placing a caliper on the level at which the gradient begins to rise and finished at the first peak (early systolic peak ESP)
what arteries is AT used?
carotid arteries
renal arteries
peripheral arteries
<15% stenosis NASCET
deceleration, spectral broadening
PSV <125 cm/s
16-49% stenosis NASCET
pansystolic, spectral broadening
PSV <125 cm/s
50-69% stenosis NASCET
pansystolic, spectral broadening PSV >125 cm/s EDV <110 cm/s OR ICA/CCA PSV ratio >2 but <4
70-79% stenosis NASCET
pansystolic spectral broadening PSV >270 cm/s EDV >110 cm/s OR ICA/CCA PSV ratio >4
80-99% stenosis NASCET
EDV >140 cm/s
complete occlusion NASCET
no flow, terminal thump
what could history of the patient include?
- previous stroke
- smoker (now or prior)
- elevated BP-HBP
- elevated cholesterol-hyperlipidmia
- diabetic
- family history of any of the above
what are indications on req or history from referring physician?
- headaches
- bruit heard on auscultation by physician
- present stroke
- TIA
- vertigo/dizziness
- amaurosis fugax
- limb wekaness-indicate which side
what could a bruit heard in the carotid artery be an indicaton of?
a carotid artery stenosis
when are bruits more commonly heard in the carotid artery?
70-90% stenosis
what can a false bruit be caused by?
- a murmur radiating from a stenosed aortic valve
- external carotid disease
- intraluminal turbulence in the ICA
- arteriovenous malformations
- external compression from thoracic outlet syndrome
- scarring due to neck surgery
- tumor
what should be written on a technical report?
- review images
- write PSV, EDV and ratio where indicated for all vessels
- draw areas of plaque
- comments of collateral or stenosis when present
- if TDS happens it should be mentioned
The ratio of ICA/CCA would be less than _____ if there is no hemodynamically significant stenosis
2
if ICA PSV is 120cm/s and the CCA PSV is 80cm/s –what would the ratio be ?
1.5
if ICA PSV is 150cm/s and the CCA PSV is 75cm/s-what would the ratio be?
2
what are some cases where a hemodynamically significant stenosis should be reported?
- velocity doubles from CCA to ICA
- the PSV of ICA is >125 cm/s
- the ratio is 2 or more
when the EDV of the ICA is _____ cm/s, there is a ______ stenosis
> 140 cm/s
>80%
What is a carotid endarterectomy (CEA)?
surgical procedure to remove the atheromatous plaque material or blockage in the lining of the artery
what is CEA done for?
reduce the risk of stroke
when is CEA considered?
if the artery is narrowed by more than 70% especially if the patient is symptomatic
what is important criteria in most severe stenoses?
measurement of the end diastolic velocity
how is homogenous and heterogenous plaque indicated?
by filling in the area with the approproate density of echoes
how is calcified plaque drawn?
indicated with XXXXXXX
how do you draw an occlusion?
completely fill in the lumen
what is trickle flow?
considered to be pre-occlusive with just a trickle of flow within lumen
what do we do to see trickle flow?
- decrease colour velocity scale (PRF)
- Increase the colour gain
- Increase the SV size to the lumen width
do we document collaterals?
yes
take imahes and write in the comments
when may collateral flow occur?
- high grade or complete occlusion of ICA
- SSS
- CCA occlusion
when internalization occurs of the ECA how will the ECA appear?
lower resistant with high flow
if the ICA and occludes and the ECA suffers from internalization, what happens to the CCA?
becomes more high resistant
confetti sign suggests?
bruit
string sign/trickle onflow
pre occlusion
what is importatnt when characterizong plaque?
length
Sessile
a longer area of plaque
what plaque causes less disturbance of flow?
longer area causes less than a short area of protruding plaque
dropout from calcification may occur, how do we check if thats the case?
- assess the colour before and after plaque
- assess the doppler signal before and after plaque
in areas of narrowed lumen where should the angle correct be?
parallel to the ealss of the vessels
do we make the gate bigger or smaller in the narrow flow zone?
open up and make bigger
when is angle correct not necessary?
opthalmic artery flow because direction of flow is only important
what outlines soft plaque?
colour
when do we use a straight colour box?
- tortous vessels
- TRV vessels
what does post stenotic turbulent flow look like?
- loss of sharp upstroke
- jagged peak
- flow above and below baseline
transient ischemic attack (T.I.A)
when a patients symptoms resolve in <24 hours
how long do TIA’s last?
usually sudden and brief, often lasting only 10 or 15 minutes.
TIA’s are _____ in nature
multiple
when are TIA’s at a high risk for stroke?
patients who present with multiple TIA’s in a short period of time
where do TIA’s effect in the body?
affect the side of the body opposite its physical location in the brain
what is the exception for where TIA’s effect in the body?
amaurosis fugax
reversible ischemic neurlogical deficit (R.I.N.D)
symtoms lasting >24 hours but completely resolve thereafter
cerebral vascular accident (C.V.A)
symtoms that do not resolve and leave the patient with a permanent deficit
do CVA’s resolve?
no
what is amaurosis fugax?
a degree of blindness affecting one eye which is usually described by the patient as “like a shade being pulled over one eye”
how may the vison of a person with amaurosis fugax appear?
affect all or only a portion of the patient’s visual field or it may simply be “blurred vision”
syncope
episodes of blacking out
dizziness
may be accompanied by nausea
numbness
affecting the face, tongue, etc or the limbs could be effected
hemiparesis
Unilateral weakness of a limb or limbs on one side of the body
aphasia
loss of ability to vocalize
what are the symptoms of CVA?
- syncope
- dizziness
- numbness
- altered speech
where does amaurosis affect?
the eye on the same side as the source of the problem
what may a headache suggest?
indicate insufficient cerebral perfusion or impending stroke
what is the most common cause of stroke?
infarction of the middle cerebral artery (MCA)
what does the brains left hemisphere control?
the right side of the body
what are the signs and symptoms of an affected MCA?
- dysphasia or aphasia
- contralateral hemoparesis more severe in face and upper extremity
- confusion
- behavoral changes
- agitated delirium
what are the signs and symptoms of an affected ICA?
- contralateral weakness
- numbness or paralysis
- ipsilateral amaurosis fugax
- aphasia
- bruit
- occasional alteration in level of consciousness
what are the signs and symptoms of an affected ACA?
- contralateral hemiparesis, especially of lower extremitiy
- incontinence
- loss of cordination
- impaired motor and sensory functions
what are the signs and symptoms of an affected PCA?
- dyslexia
- coma without paralysis
what are the signs and symptoms of an affected vetevbrobasilar?
- facial numbness
- diplopia
- vertigo
- dysphagia
- amnesia
- ataxia
carotid/anterior circulation symtoms
UNILATERAL motor and sensory deficits
- paresthesia
- dysphasia and or aphasia
- monocular disturbances
- behavioural abnormalities
paresthesia
tingling or numbness on one side
vertebrovascular/posterior circulation symptoms
BILATERAL motor and sensort deficits
- vertigo
- ataxia
- bilateral visual fiels defects
- bilateral paresthesia
- drop attack
vertigo
a spinning sensation
drop attack
falling to ground without other symptoms or loss of conciousness
what are non localizong symtoms?
- dizziness
- syncope
- headache
- confusion
what should a physical exam include?
palpation of easily accessible arteries
- Auscultation of carotid and vertebral arteries for bruit
- brachial systolic pressures on both arms
- ophthalmoscopy
what does a pressure diiference of 20 mmHg in both arms suggest?
Suspicious for SSS
what patients are treated with endarterectomy?
most symptomatic patients with a stenosis >70% diameter reduction are treated surgically
-some are preformed in asymtomatic patients with a stenosis of >60%
balloon angioplasty and atherectomy
non-surgical methods for treating carotid athersclerosis as well as other vessels
what does balloon angioplasty and atherectomy have a risk of?
acute embolization
what is offered as medical therapy in patients with carotid disease?
in the form of daily aspirin use
who is aspirin given to?
patients with mild to moderate levels of stenosis and no history of hypertension
what may be given to patients with TIA’s?
anticoagulents and platelet inhibitors
Clopidogrel(Plavix)
platelet inhibitor
heparin
antiocoagulant
aspirin
anticoagulent
what do you do of your patient has subclavian steal?
bilateral brachial pressure systolic measurments must be taken
how do you know which side the stenosis is when measuring brachial pressure?
the side with the innominate or subclavian stenosis will have lower pressure
-damped or monophasic flow pattern
what difference in pressure will the arm have with SSS?
40 mm/Hg difference
if your patient has an occluded ICA or high grade stenosis:
-the OA flow will be reversed on the side of the occlusion
