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MIDS 197 > Ch 5 Parasternal CD > Flashcards

Ch 5 Parasternal CD Flashcards

1
Q

What is the doppler effect?

A

A change in frequency caused by the motion of a sound source, receiver or reflector

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2
Q

Doppler echocardiography is based on the change in what?

A

In frequency of the backscattered signal from small moving structures (ex RBCs)

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3
Q

If the motion is moving towards, the received echo has a lower or higher frequency?

A

Higher

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4
Q

If the motion is moving away, the received echo has a lower or higher frequency?

A

Lower

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5
Q

What is a doppler shift?

A

The difference in frequency b/w the transmitted frequency (Ft) + the scattered signal received back at the transducer (Fs)

(DS = Fs - Ft)

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6
Q

What is the audible range of doppler shifts?

A

0-20 KHz

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7
Q

What is a positive doppler shift?

A

When the RBCs are moving TOWARDS the probe

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8
Q

What is a negative doppler shift?

A

When the RBCs are moving AWAY from the probe

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9
Q

Blood flow towards the probe is going to appear above or below the baseline?

A

Above (antegrade) - due to positive doppler shift in our color scale

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10
Q

Blood flow away from the probe is going to appear above or below the baseline?

A

Below (retrograde) - due to negative doppler shift in our color scale

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11
Q

Explain what each variable is in the doppler equation: V = c (Fs-Ft) / 2 Ft (cos)

A

V: velocity of blood flow
C: speed of sound in blood
Ft: transducer frequency
Fs: backscattered frequency
Cos: angle b/w ultrasound beam + direction of blood flow

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12
Q

When applying cardiac doppler, should the u/s beam be parallel or perpendicular to blood flow?

A

Parallel

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13
Q

Is cosine equal to 1 or 0?

A

Cos = 1

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14
Q

Will a doppler shift be recorded/detected if the u/s beam is perpendicular to blood flow?

A

Nope

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15
Q

Should we use angle correct for cardiac doppler applications? Why or why not?

A

No! B/c of the chance that the “correction” will be erroneous (wrong + inaccurate)

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16
Q

How can we avoid errors in calculating the velocity of blood flow?

A

By having the intercept angle of the u/s beam + the direction of blood flow parallel

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17
Q

What are the 2 intracardiac flow patterns we see in the heart?

A

Laminar + disturbed/turbulent flow

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18
Q

What is laminar flow?

A

Movement of fluid along well defined parallel stream lines with uniform flow velocities

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19
Q

In 3D, what does laminar flow consist of?

A

Concentric layers (lamina) or flow, each with a predictable + uniform direction and velocity

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20
Q

What is disturbed/turbulent flow?

A

Blood flow in multiple directions + velocities (is chaotic)

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21
Q

When would disturbed/turbulent flow occur?

A

Downstream from areas of narrowing

(ex: stenotic + regurgitant orifices or an intracardiac shunt)

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22
Q

Is a small amount of turbulent flow as the valves close normal in people?

A

Yes

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23
Q

What are flow velocity profiles?

A

Spatial distribution of velocities in a cross section: at a specific intracardiac location + at a specific time in the cardiac cycle

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24
Q

What is a flat flow velocity profile?

A

Parallel streamlines in a laminar flow pattern with the same velocity

(image shows all arrows in a straight line going in same direction)

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25
Q

List structures in the heart that would have flat flow velocity profiles?

A

-Flow across MV + TV
-Flow across prox AO + PA

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26
Q

What is a parabolic flow velocity profile?

A

Flow velocity is higher in the center + lower at the walls

(image shows arrows going in same direction, but not at same speed)

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27
Q

When would we see parabolic flow velocity profiles in the heart?

A

Once laminar flow is achieved in long, straight blood vessels under steady flow conditions

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28
Q

A blunted version of parabolic flow occurs due to what 2 things?

A

-Pulsing of vessels
-Shorter vessel length

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29
Q

What type of flow must be achieved before parabolic flow can?

A

Laminar flow - in long straight vessels under steady flow conditions

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30
Q

CD is a form of what?

A

PW doppler

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31
Q

CD uses multiple sample volumes along what?

A

Multiple scan lines

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32
Q

Are CD images angle dependent?

A

YES, must be parallel

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33
Q

CD is subject to aliasing once velocities pass what?

A

The nyquist limit (1/2 the PRF)

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34
Q

Is the nyquist limit higher or lower in CD?

A

Lower! B/c the mean doppler shifts/velocities are detected at each sample volume

(color nyquist limit is lower than in all other forms of doppler)

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35
Q

Is the color scale + the nyquist limit the same thing?

A

Yes

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36
Q

Does CD give us qualitative or quantitative info?

A

Qualitative

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37
Q

What is the min frame rate we want?

A

20

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38
Q

List 4 things that CD provides qualitative info on?

A

-A specific area of interrogation (color box)
-Direction of flow (BART + zero doppler shift appears black)
-Velocity of flow (not as specific as spectral doppler)
-Type of flow (laminar vs turbulent)

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39
Q

How to differentiate b/w laminar + turbulent flow with CD?

A

Laminar: smooth sold color pattern

Turbulent: aliasing with mosaic colors due to higher velocities

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40
Q

Is laminar or turbulent flow normal in the heart?

A

Laminar

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41
Q

How to differentiate b/w high + low flow velocities with CD?

A

High: brighter/vibrant hued colors which are farther away from the black zero doppler shift area on scale (baseline)

Low: deeper hued colors which are closer to the black zero doppler shift area on scale (baseline)

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42
Q

Do we use CD as a guide for spectral doppler interrogation?

A

Yes! For PW + CW

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43
Q

What is the general range our scale should be in?

A

50-90 cm/s (depends on structure of interest)

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44
Q

Why is it important to know the normal scale values for each valve?

A

Helps us optimize where to put our scale

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45
Q

What is regurgitation?

A

Backflow of blood through an incompetent valve

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46
Q

What is regurgitation in the semilunar valves called?

A

Insufficiency

47
Q

What does valve regurgitation look like with CD?

A

Can be primarily one color or mosaic

48
Q

What is a stenosis?

A

An area that is smaller than anatomically ideal

(m/c referred to with valves)

49
Q

Stenosis can occur in specific anatomic locations due to what 2 factors?

A

-Hypertrophy
-Scarring

50
Q

What does stenosis look like with CD?

A

Expect mosaic colors

51
Q

What would intracardiac shunts appear with CD?

A

Can be primarily one color or mosaic

52
Q

What would outflow tract obstructions appear with CD?

A

Mosaic

53
Q

How would regurg, stenosis, shunts + outflow tract obstructions appear on CD?

A

Regurg + shunts: 1 color or mosaic
Stenosis + obstructions: mosaic

54
Q

Explain how the flow travels in PLAX?

A

-Flows from LA through MV to LV
-Flows from LV through AoV to AO

55
Q

In PLAX, where do we assess for potential anomalous (abnormal) flow?

A

Through the IVS (looking for possible ventricular septal defects)

56
Q

What is the primary goal we want to establish in regards to flow in our views?

A

To establish normal laminar flow between structures

57
Q

What color should flow be in PLAX as it moves from LV, LVOT into AoV during systole?

A

Red

(small amounts of blue due to change of direction in flow as valve closes)

58
Q

What color would AoV regurg be in diastole in PLAX?

A

Blue

59
Q

What would mosaic colors present at valves possibly indicate?

A

Stenosis or other valvular defects

(ensure scale is set appropriately)

60
Q

What should we do to our scale if we are seeing a bunch of mosaic colors?

A

Increase scale to remove aliasing

61
Q

Where should we put our CD box when assessing the AoV?

A

Extends from part of LV + goes just past AoV

(if regurg is seen, extend box over majority of LV to include whole jet)

62
Q

What is the scale/nyquist limit range for semilunar valves?

A

60-90

(higher scale for these valves b/c they have higher velocity + pressure)

63
Q

What color should flow be in PLAX as it moves from LA to LV in diastole?

A

Red

64
Q

What color would regurg be from LV to LA in systole in PLAX?

A

Blue

65
Q

Where should the CD box be placed when assessing the MV?

A

Should cover whole LA

66
Q

What should the scale/nyquist limit range be for AV valves?

A

60-70

67
Q

What is the primary goal when evaluating the IVS in PLAX?

A

-To ensure no shunt (abnormal communication) from LV to RV

-Can detect other flow accelerations + anomalies in LV such as LVOT obstructions

68
Q

Where should the CD box be when assessing the IVS in PLAX?

A

Must cover entire length of IVS with overlap of RV + LV

(should be NO color passing b/w ventricles)

69
Q

In RVIT, what color should flow be from the RA to RV in diastole?

A

Red

(can sometimes see red flow from IVC into RA)

70
Q

In RVIT, what color would regurg be from RV to RA in systole?

A

Blue

71
Q

Where should the CD box be when assessing the TV in RVIT?

A

Covers whole RA + slightly past TV

72
Q

What would be the hemodynamic consequences of severe TV regurg in RVIT?

A

Would back up into venous circulation causing an increased fluid volume into IVC

73
Q

In RVOT, what color should flow be as it moves from RV, RVOT into PV during systole?

A

Blue

74
Q

In RVOT, what color would regurg be from PV in diastole?

A

Red

75
Q

Where should the CD box be when assessing the PV in RVOT?

A

Extends above RVOT + along PA

76
Q

Would stenosis of the PV cause increased afterload or preload?

A

Afterload of RV

(increases force + pressure the RV has to contract against + push blood into pulmonary circulation)

77
Q

Does the PV or AoV have higher pressure?

A

AoV

78
Q

What structures can we evaluate in PSAX - AoV?

A

-Flow over AoV
-Flow from RA, TV, RV
-Flow from RV, RVOT, PV, PA
-Potential anomalous/abnormal flow through IAS + IVS

79
Q

In PSAX AoV, what color should flow be through the AoV in systole?

A

Red

(regurg from AoV to LV is blue)

80
Q

Which view are we possibly able to view portions of the RCA + LCA?

A

PSAX AoV

(must lower scale b/c coronaries have lower velocity)

81
Q

Where should we place our CD box when assessing the PSAX AoV?

A

Must fully cover the zoomed in AoV (assess IVS for VSDs)

(we are “enface” to the valve - meaning face to face with it)

82
Q

What is the only exception where we would see flow exiting the AoV in PSAX AoV?

A

Within the coronaries (RCA, LCA), otherwise should NOT see flow exiting

83
Q

In PSAX AoV - TV, what color should flow be when moving from RA to RV in diastole?

A

Red (regurg from RV to RA in systole is blue)

84
Q

Mosaic antegrade flow through the TV indicates what?

A

Indicates TV stenosis

85
Q

In PSAX AoV, where should our CD box be when assessing the TV?

A

Extends just past TV into RV + covers entire RA

86
Q

In PSAX AoV - PV, what color should flow be when moving from RVOT, PV to RA in systole?

A

Blue (regurg from PA to RV in diastole is red)

87
Q

In PSAX AoV - PV, anomalous/abnormal flow from below the PV from the right side of the PA could indicate what?

A

A patent ductus arteriosus

(remnant from fetal circulation)

88
Q

In PSAX AoV, where should our CD box be when assessing the PV?

A

Extends just passed PV into the RVOT + includes majority of PA

89
Q

What does color over the IAS tell us in PSAX AoV?

A

Tells us if there is communication b/w the LA + RA

(possible ASD)

90
Q

What is a patent foramen ovale?

A

Failure of the fetal communication (foramen ovale) to close after birth

91
Q

What is an atrial septal defect (ASD)?

A

Hole through IAS

92
Q

What should the scale/nyquist limit range be set at to assess the IAS?

A

Decreased to 40-50

93
Q

In PSAX MV, what color should flow be when moving from LA to LV in diastole?

A

Red (regurg from LV to LA in systole is blue)

94
Q

Where should we place our CD box in PSAX MV?

A

Over MV and/or IVS (to look for abnormal communication b/w LV + RV)

95
Q

What is the significance of clarifying “structure of interest”?

A

To clarify what the star of the show is + the reason why we are taking the image

96
Q

Is PSAX PM CD clip always obtained?

A

Nope, only when wanting to evaluate for presence of a VSD

97
Q

Where would we place our CD box in PSAX PM + apex?

A

Over entire IVS

(do this if we are expecting to see an IVS defect)

98
Q

Is PSAX apex CD clip always obtained?

A

Nope, only when wanting to evaluate for presence of a VSD

99
Q

What is the most important factor when optimizing for doppler imaging?

A

The alignment of the u/s beam!!

-Perpendicular to flow = no doppler shift
-Be as parallel as possible (tilting + rotating helps align the beam)

100
Q

List 5 things we can adjust to optimize the controls for CD imaging?

A

-Color box size
-Velocity scale (nyquist limit)
-CD + 2D gains
-Wall filter
-Baseline

101
Q

The CD box is adjustable in what 3 ways?

A

Position, length + width

102
Q

The size of the CD box affects what?

A

Frame Rate: larger box reduces FR + makes image quality worse

Scale: longer + deeper boxes reduce PRF

103
Q

Under what circumstances would we increase our scale?

A

-Reduce aliasing
-Smooth flow in high velocities of normal

104
Q

Under what circumstances would we decrease our scale?

A

For visualization of slower velocity flow

105
Q

What size CD box is best?

A

Shorter boxes with shallow depths

106
Q

Is it possible to make things look worse/better than what they are accidentally when adjusting our scale + gains?

A

Yes! Ensure settings on machine are right

107
Q

Does color have difficulty overriding grayscale at times?

A

Yes

108
Q

What technique do we do to ensure we are at correct CD gains?

A

Increase the gain to where we see “speckling”, then decrease it to right below that

(must optimize + adjust CD gain in each view)

109
Q

What does adjusting our wall filter do?

A

Enables removal of doppler shifts from display

110
Q

What happens when we increase + decrease our wall filter?

A

Increase/high filter: excludes low velocity signals from valves or walls
(image shows correct vessel fill in)

Decrease/low filter: allows visualization of low velocity flow
(image shows color bleeding outside vessel)

111
Q

Where is the baseline typically set?

A

In middle of color scale (black area) - but can be moved in 1 direction or another to remove aliasing

112
Q

What is the baseline especially useful for?

A

Measurements for evaluating regurg

113
Q

When would we shift the baseline?

A

When pathology is present

MIDS 197 (15 decks)

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