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Cardiac Ultrasound > Doppler > Flashcards

Doppler Flashcards

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
Q

what does the PRF determine

A

frequency shift

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26
Q

maximum frequency shift

A

1/2 PRF

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27
Q

Nyquist limit = ?

A

1/2 PRF

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28
Q

what happens when the Doppler shift is greater than the nyquist limit?

A

aliasing

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29
Q

what is aliasing

A

false display of velocity (wraps around image)

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30
Q

relationship between depth and PRF

A

inverse

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31
Q

3 factors determining aliasing

A

increased depth
low PRF
high velocity

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32
Q

how to resolve aliasing

A

use CW
shallower depth
lower f transducer
shift baseline

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33
Q

has multiple sample volumes or gates along scan line

A

color PW

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34
Q

sample volume is measured in max or mean velocity?

A

mean

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35
Q

BART system

A

blue away

red towards

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36
Q

we use color doppler to

A

visualize anatomic and hemodynamic info at the same time

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37
Q

what is an autocorrelator

A

compares frequency shift on a scan line to the other gates on the scan line
color is assigned where the f shift exists

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38
Q

what does color doppler display include?

A

blood flow direction and velocity
frequency aliasing
laminar and turbulent flow
timing of color doppler signals

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39
Q

what does frame rate mean

A

frames per second

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40
Q

frame rate depends on

A

depth of sector
sector width
density of scan lines
number of gates along each scan line

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41
Q

how does high frame rate affect sensitivity?

A

high frame rate = good sensitivity

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42
Q

what can we change on the frame rate of color doppler

A

depth of sector

sector width

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43
Q

how can we increase the frame rate / sensitivity in color doppler

A

narrow sector / increase PRF / shallower depth

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44
Q

can color doppler alias?

A

yes, it is PW

45
Q

graphic display of blood flow velocities over time

A

spectral doppler

46
Q

FFT processor stands for?

what does it analyze?

A

fast Fourier transform

frequency shift

47
Q

y axis of spectral doppler

A

velocity and direction of blood flow

48
Q

x axis of spectral doppler

A

time

49
Q

positive shift in doppler is

A

above baseline

50
Q

negative Doppler shift appears

A

below baseline

51
Q

t or f: color of doppler represents average f shifts in the area

A

true

52
Q

do blood cells move at equal velocities in doppler?

A

no, they each create different doppler shifts

53
Q

how is intensity/brightness related to # of RBC moving at that velocity at that time

A

direct

54
Q

streamline flow

A

laminar

55
Q

turbulent flow

A

flow is irregular

56
Q

which has range resolution?

CW or PW?

A

PW

57
Q

does CW have range resolution or range ambiguity?

A

range ambiguity

58
Q

Doppler Controls:

Reject =

A

reduces # of shades of grey to help with envelope detection

59
Q

Doppler Controls:

compression / dynamic range =

A

reduces # of shades of gray

60
Q

Color of TR in apical 4?

A

blue, away from trx

61
Q

Color doppler:
White means?
Black means?

A

high f shift

no f shift

62
Q

audible range (doppler range)

A

20 Hz - 20 KHz

63
Q

cosine of 90 =

A

0

64
Q

strive to be parallel to flow or angle less than __ degrees

A

20

65
Q

spectral doppler provides?

A

direction velocity
duration
timing / point in cardiac cycle

66
Q

acceleration time

A

period before spike in m mode (onset of flow to peak)

67
Q

deceleration time

A

peak of curve in m mode (peak to end of flow)

68
Q

what views do we use to find LVOT / AV velocity

A

apical 3 or 5

LVOT is always less than AV

69
Q

shape of LVOT blood flow tracing

A

V shape

70
Q

LVOT blood flow time

A

.7 - 1.1 m/s

71
Q

AV blood flow time

A

.2 - .4 m/s higher than LVOT due to lower CSA at leaflet tips

72
Q

it is common practice to evaluate the AV velocity with CW or PW?

A

CW

73
Q

normal peak velocity of AV

A

1 m/s

74
Q

normal AVA (aortic valve area)

A

3 - 4 cm2

velocity > 4 = severe aortic stenosis
AVA > 2 cm squared
AVA < .7 cm sq = severe stenosis

75
Q

what view do we get the best RVOT and PA velocity

A

short axis or sometimes long axis

76
Q

max velocity of RVOT / PA

A

1 m/s

77
Q

what window do we get LV inflow in

A

apical 4 at leaflet tips

78
Q

normal E velocity

A

1 m/s

79
Q

normal A velocity

A

2-4 cm/s

80
Q

E/A ratio should be greater than or less than 1

A

greater than 1

81
Q

RV inflow velocity

A

.3 - .7 m/s

82
Q

PW sample should be positioned at

A

leaflet tips

83
Q

TR provides monographers with ability to calculate __

A

pulmonary artery pressures

84
Q

Is TR normal?

A

yes, 70 to 80% of people have a small amount

85
Q

how does blood flow into the LA

A

via 4 pulmonary veins

RU, LU, RL, LL

86
Q

PV that is most widely used

A

RUPV

87
Q

view we want for Pulmonary vein flow

A

apical 4

88
Q

PW or CW for pulmonary vein flow

A

PW, has pulse range resolution

89
Q

where do we place the sample volume for pulmonary vein

A

1-2 cm into pv

90
Q

PV flow has 3 distinct waveforms…

A

systolic antegrade flow
diastolic antegrade flow
atrial retrograde flow

91
Q

S wave

A

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
Q

D wave

A

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
Q

AR wave

A

atrial flow reversal
retrograde flow into PV after atrial contraction
normal velocities are low

94
Q

Severe MR may cause blunted __ wave (retrograde flow)

A

S

95
Q

pulmonary vein characteristics are a good way to determine ___

A

diastolic dysfunction

96
Q

view for hepatic vein

A

subcostal long axis view of IVC

97
Q

hepatic vein flows into

A

RA

98
Q

hepatic flow is the same as ___ flow

A

IVC flow

99
Q

is spectral doppler of hepatic flow more accurate than IVC?

A

yes, velocities increase with respirations in IVC

100
Q

Hepatic vein waveforms

A

S - systolic forward flow
D - diastolic forward flow
AR - retrograde flow

101
Q

what happens with respiratory variation and flow

A

inspiration increases antegrade flow

expiration increases retrograde flow

102
Q

TR

A

75% functional - normal

24% structural - something wrong with valve

103
Q

we can calculate TR pressures using ___

A

pulmonary pressures

104
Q

normal velocity of TR

A

less than 2 m/s

105
Q

what does the PRF in PW equal?

A

sampling rate

106
Q

which doppler type has range resolution

A

PW

107
Q

LV inflow velocity

A

2-4 cm/s

108
Q

rv inflow seen in what view

A

apical or RV inflow view

Cardiac Ultrasound (2 decks)

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