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Vascular Boards > Chapter 18: Carotid Duplex > Flashcards

Chapter 18: Carotid Duplex Flashcards

1
Q

over estimating of the disease process (thinking theres a stenosis) can be from

A

cardiac output (faster flow on young people)
tortuous vessel
compensatory flow
inappropriate doppler angle

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2
Q

under estimation of the disease process

A

jet of accelerated flow missed
long smooth plaque formation
stenosis are area of dilation (carotid bulb)
inappropriate doppler angle

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3
Q

patient positioning

A

supine
neck slightly hyperextended
head turned slightly

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4
Q

what is used to Carotid imaging

A

spectral analysis
continous wave doppler
pulsed doppler

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5
Q

continous wave doppler

A

two piezo-electric crystals (one constantly sending and one receiving)
no range resolution
fixed sample size

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6
Q

pulsed doppler

A

crystals send then receive
high range resolution
variable sample size
well defined spectrum

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7
Q

color doppler

A

color displays average frequencies and direction
pulsed doppler eval multiple sample sites
slower scan rates

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8
Q

hypoechoic and homogeneous level echoes

A

low level echoes of similar appearance
fatty streaks
found in person of all ages

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9
Q

homogenous echoes

A

low to medium level echoes of similar appearance

fibrous plaque

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10
Q

echoic and heterogenous echoes

A

all levels of echoes

complex plaque of intraplaque hemorrhage

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11
Q

hyperechoic echoes

A

bright reflective echoes

shadowing from calcium deposits

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12
Q

suface characteristics

A

smooth
slightly irregular
grossly irregular

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13
Q

a stenosis should be visible from

A

at least two projections

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14
Q

occluded artery

A

varying echogenicity but vessel completely filled

vessel motion: horizontally or piston like

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15
Q

ICA doppler signals

A

high pitched and continous compared to ECA

waveform has rapid upstroke and down stroke with high diastolic component

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16
Q

ECA doppler signals

A

pulsatile, similar to peripheral vessels

rapid upstroke and down stroke with low flow in disatole

17
Q

temporal tap technique

A

tapping STA you will see vibration in ECA waveforms

18
Q

CCA doppler signals

A

similar to both ICA and ECA

19
Q

Stenosis doppler signal

A 
high pitched sound and waveform with higher velocity
spectral broadening (representing turbulence)
loss of spectral window (represents loss of laminar flow)
20
Q

distal to stenosis doppler

A

distrubed flow patterns

turbulent, bidirectional, dampened and monophasic

21
Q

when high resistant flow patterns in ICA, consider

A

disease at carotid siphon ( S shaped part of ICA)

22
Q

diminished CCA velocities bilaterally may indicate

A

poor cardiac output or stroke volume

23
Q

diminished velocities unilaterally suggest

A

proximal disease of innominate or CCA

24
Q

Normal PSV

A

<125 cm/sec

25
Q

Less than 50% stenosis

A

PSV <125cm/sec

26
Q

50-79% stenosis

A

PSV >125cm/sec

EDV <140 cm/sec

27
Q

80-99% stenosis

A

PSV >125cm/sec

EDV >140cm/sec

28
Q

NASCET criteria > / = 70% stenosis

A

ICA/CCA ratio >/= 4.0

highest ICA divided by Mid CCA

29
Q

Occlusion signals

A

CCA may have low or absent diastolic component
collaterals (ECA high diastolic flow)
Absent ICA signal or pre-occlusive thump

30
Q

absent signal may indicate occlusion but what can never be ruled out

A

a very significant stenosis

31
Q

alaising is

A

misrepresenttation of high doppler signal due to limitations of equipment being used
PRF is too low

32
Q

maximum frequency is

A

1/2 PRF

33
Q

nyquist limit

A

flow greater than 1/2 PRF cannot be displayed

waveform has a flat crew cut appearance

34
Q

methods of increasing the PRF/Nyquist limit

A 
decrease baseline
increase doppler scale
change transducer frequency
change angle of insonation
decrease depth
use CW doppler
35
Q

mirror imaging (crosstalk)

A

doppler shifts above and below baseline
display duplicate spectrum
artifact from strong reflectors or too much gain

36
Q

Helical flow occurs when

A 
flow moves into a wider portion of the vessel (bulb)
doppler shifts above and below baseline
spectral waveforms different
doppler angle constantly changing
flow is not laminar
spectral broadening is present
37
Q

Intraoperative monitoring is used to

A

identify defects secondary to surgery and/or areas of platelet aggregation
eval wall irregulatirty

38
Q

intraoperative monitoring technique

A 
12MHz 
sterile sleeve containing gel
wound filled with sterile saline
areas of flow disturbance identified 
gray scale imaging for wall defects

Vascular Boards (30 decks)

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