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Doppler Flashcards

(108 cards)

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1
Q

What does doppler focus on?

A

hemodynamics and physiology

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2
Q

___ Doppler, Austrian physicist, described the Doppler effect in the year ___

A

Christian, 1842

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3
Q

Describe the doppler effect

A

f increases as sound source moves closer

f decreases as sound source moves away

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4
Q

Doppler shift is the difference between

A

transmitted frequency and received frequency

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5
Q

positive doppler shift

A

rf > tf

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6
Q

negative doppler shift

A

rf < tf

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7
Q

is Doppler shift within the audible range?

A

yes

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8
Q

how is Doppler shift related to speed

A

direct

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9
Q

measured velocity = ___ x cosine

A

true velocity

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10
Q

in the doppler equation, v stands for

A

velocity of blood flow

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11
Q

in the doppler equation, cos stands for

A

angle of blood flow and US beam

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12
Q

in the doppler equation, change in frequency stands for

A

Doppler shift (can be pos. or neg.)

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13
Q

in the doppler equation, 2 stands for

A

double Doppler shift (reception and reflection)

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14
Q

in the doppler equation, fo stands for

A

known transmitted frequency

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15
Q

in the doppler equation, C stands for

A

speed of sound in soft tissue

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16
Q

how is change in frequency or Doppler shift related to reflector

A

direct

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17
Q

two types of doppler

A

CW

PW

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18
Q

simultaneous 2D imaging and Doppler

A

duplex imaging

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19
Q

how many crystals in CW doppler

A

2
one is always transmitting
one is always receiving

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20
Q

benefit of CW

A

accurate measurement of high velocity

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21
Q

cons of CW

A

poor range resolution

range ambiguity

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22
Q

what is range resolution?

A

being able to select the exact location where velocities are measured

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23
Q

what is a PEDOF probe

A

non imaging CW transducer
high signal to noise ratio, increased sensitivity
small footprint
easy to angulate

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24
Q

how many crystals in a PW doppler

A

1 crystal

alternates transmission and reception

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25
what does the PRF determine
frequency shift
26
maximum frequency shift
1/2 PRF
27
Nyquist limit = ?
1/2 PRF
28
what happens when the Doppler shift is greater than the nyquist limit?
aliasing
29
what is aliasing
false display of velocity (wraps around image)
30
relationship between depth and PRF
inverse
31
3 factors determining aliasing
increased depth low PRF high velocity
32
how to resolve aliasing
use CW shallower depth lower f transducer shift baseline
33
has multiple sample volumes or gates along scan line
color PW
34
sample volume is measured in max or mean velocity?
mean
35
BART system
blue away | red towards
36
we use color doppler to
visualize anatomic and hemodynamic info at the same time
37
what is an autocorrelator
compares frequency shift on a scan line to the other gates on the scan line color is assigned where the f shift exists
38
what does color doppler display include?
blood flow direction and velocity frequency aliasing laminar and turbulent flow timing of color doppler signals
39
what does frame rate mean
frames per second
40
frame rate depends on
depth of sector sector width density of scan lines number of gates along each scan line
41
how does high frame rate affect sensitivity?
high frame rate = good sensitivity
42
what can we change on the frame rate of color doppler
depth of sector | sector width
43
how can we increase the frame rate / sensitivity in color doppler
narrow sector / increase PRF / shallower depth
44
can color doppler alias?
yes, it is PW
45
graphic display of blood flow velocities over time
spectral doppler
46
FFT processor stands for? | what does it analyze?
fast Fourier transform | frequency shift
47
y axis of spectral doppler
velocity and direction of blood flow
48
x axis of spectral doppler
time
49
positive shift in doppler is
above baseline
50
negative Doppler shift appears
below baseline
51
t or f: color of doppler represents average f shifts in the area
true
52
do blood cells move at equal velocities in doppler?
no, they each create different doppler shifts
53
how is intensity/brightness related to # of RBC moving at that velocity at that time
direct
54
streamline flow
laminar
55
turbulent flow
flow is irregular
56
which has range resolution? | CW or PW?
PW
57
does CW have range resolution or range ambiguity?
range ambiguity
58
Doppler Controls: | Reject =
reduces # of shades of grey to help with envelope detection
59
Doppler Controls: | compression / dynamic range =
reduces # of shades of gray
60
Color of TR in apical 4?
blue, away from trx
61
Color doppler: White means? Black means?
high f shift | no f shift
62
audible range (doppler range)
20 Hz - 20 KHz
63
cosine of 90 =
0
64
strive to be parallel to flow or angle less than __ degrees
20
65
spectral doppler provides?
direction velocity duration timing / point in cardiac cycle
66
acceleration time
period before spike in m mode (onset of flow to peak)
67
deceleration time
peak of curve in m mode (peak to end of flow)
68
what views do we use to find LVOT / AV velocity
apical 3 or 5 | LVOT is always less than AV
69
shape of LVOT blood flow tracing
V shape
70
LVOT blood flow time
.7 - 1.1 m/s
71
AV blood flow time
.2 - .4 m/s higher than LVOT due to lower CSA at leaflet tips
72
it is common practice to evaluate the AV velocity with CW or PW?
CW
73
normal peak velocity of AV
1 m/s
74
normal AVA (aortic valve area)
3 - 4 cm2 velocity > 4 = severe aortic stenosis AVA > 2 cm squared AVA < .7 cm sq = severe stenosis
75
what view do we get the best RVOT and PA velocity
short axis or sometimes long axis
76
max velocity of RVOT / PA
1 m/s
77
what window do we get LV inflow in
apical 4 at leaflet tips
78
normal E velocity
1 m/s
79
normal A velocity
2-4 cm/s
80
E/A ratio should be greater than or less than 1
greater than 1
81
RV inflow velocity
.3 - .7 m/s
82
PW sample should be positioned at
leaflet tips
83
TR provides monographers with ability to calculate __
pulmonary artery pressures
84
Is TR normal?
yes, 70 to 80% of people have a small amount
85
how does blood flow into the LA
via 4 pulmonary veins | RU, LU, RL, LL
86
PV that is most widely used
RUPV
87
view we want for Pulmonary vein flow
apical 4
88
PW or CW for pulmonary vein flow
PW, has pulse range resolution
89
where do we place the sample volume for pulmonary vein
1-2 cm into pv
90
PV flow has 3 distinct waveforms...
systolic antegrade flow diastolic antegrade flow atrial retrograde flow
91
S wave
systolic forward flow as a result of LA relaxation and movement of MV annulus toward apex with ventricular systole same positioning as E wave
92
D wave
diastolic forward flow during diastole occurs when there is an open conduit between PV, LA, open MV and LV usually lower velocity than S wave
93
AR wave
atrial flow reversal retrograde flow into PV after atrial contraction normal velocities are low
94
Severe MR may cause blunted __ wave (retrograde flow)
S
95
pulmonary vein characteristics are a good way to determine ___
diastolic dysfunction
96
view for hepatic vein
subcostal long axis view of IVC
97
hepatic vein flows into
RA
98
hepatic flow is the same as ___ flow
IVC flow
99
is spectral doppler of hepatic flow more accurate than IVC?
yes, velocities increase with respirations in IVC
100
Hepatic vein waveforms
S - systolic forward flow D - diastolic forward flow AR - retrograde flow
101
what happens with respiratory variation and flow
inspiration increases antegrade flow | expiration increases retrograde flow
102
TR
75% functional - normal | 24% structural - something wrong with valve
103
we can calculate TR pressures using ___
pulmonary pressures
104
normal velocity of TR
less than 2 m/s
105
what does the PRF in PW equal?
sampling rate
106
which doppler type has range resolution
PW
107
LV inflow velocity
2-4 cm/s
108
rv inflow seen in what view
apical or RV inflow view

Cardiac Ultrasound (2 decks)

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