Module 5: Echo Doppler Basics Flashcards
1
Q
What does doppler echo include? 2
A
- Colour flow imaging (Tissue doppler TDI)
- Spectral doppler
2
Q
What is three types of spectral doppler?
A
- Pulsed wave
- Continuous wave doppler
- Tissue doppler
3
Q
What do we use doppler in echo to assess? 5
A
- Flow through valves
- Pulmonary venous flow into the LA
- Hepatic venous flow
- SVC/IVC flow
- Aortic flow
differentiate tissue from blood
4
Q
What are normal vs Abnormal valve velocities?
A
5
Q
What is valvular stenosis?
A
A narrowing of the valve resulting in increased flow velocities
6
Q
When does valvular stenosis occur?
A
Occurs during forward or antegrade flow through a valve
7
Q
What is valvular regurgitation?
A
Valvular regurgitation occurs when a valve cannot coapt, or close correctly resulting in leakage, or backward flow through the valve
8
Q
What timeframe does valvular regurgitation occur?
A
During the timeframe the valve should normally be closed
9
Q
What is the three things to look out for in doppler echo?
A
- Colour
- Pulsed wave spectral
- Continuous wave spectral
10
Q
What information does doppler provide for echo?
A
- Qualitative info
- Gives us a good idea about regurgitation, stenosis, etc
11
Q
What information does pulsed wave spectral tells us about doppler echo? 2
A
- Quantitive
- Gives us a spectral signal from a specific sample spot
12
Q
What does continuous wave spectral tells us about doppler echo? 3
A
- Quantitive
- Gives us a spectral signal from a entire line of scan
- Used for very high velocities
13
Q
What is the order of images for echo?
A
- 2D/Mmode (+/- zoom)
- Colour
- Spectral (either PW or CW)
14
Q
Colour doppler is a pulsed wave technique and subject to what?
A
Aliasing
15
Q
When aliased the flow direction is what?
A
Ambiguous
16
Q
The LVOT and AV colour doppler here is what?
A
Aliased in the normal heart
17
Q
Normal flow direction depends on what?
A
The cardiac cycle
18
Q
What does the cardiac cycle add to cardiac component?
A
Dynamic component
19
Q
Colour doppler is what kind of technique?
A
Pulsed wave doppler technique with many tiny sample volumes placed in the colour box
20
Q
With Colour doppler being a PW doppler technique what does this subject it to? 2
A
The same rules as Pulsed way such as
1. Lowering frame rate
2. The Nyquist limit
21
Q
Color aliasing can be a helpful artifact in echo to do what?
A
Accessing valve pathology
22
Q
What are some advantages of colour doppler? 3
A
- Sensitivity
- Region of interest
- Laminar vs turbulent flow
23
Q
How is sensitivity good for colour doppler?
A
It can detect small amounts of blood flow
24
Q
How does region of interest help colour doppler?
A
Anatomical + hemodynamics information on one image
25
Why is seeing laminar vs turbulent flow good for Colour doppler?
We are able to see the difference because turbulent flow in the heart is almost always aliased
26
What is the disadvantages of Colour doppler? 2
1. Aliasing
2. Directional Ambiguity
27
What is directional ambiguity in terms of colour doppler? 2
1. Perpendicular flow appears as multiple colours
2. Confuses the interpretation of blood flow direction
28
When does aliasing happen in colour doppler?
At high velocities
29
What are some questions we need to ask to find out if the Colour is normal for colour doppler? 2
1. Know when to expect regurgitation on the valve you are assessing
2. Know which color regurgitation will appear on the valve you’re assessing
30
For colour doppler what will stenosis show?
Aliasing
31
During colour doppler what will regurgitation show?
A bit of aliasing right at the valve, unless the leak is really big
32
What are the steps for adjusting gain for colour doppler?
1. Turn gain up until you see speckle
2. Turn gain down just until the speckle disappear
33
Colour gains should be adjusted when?
Must be adjusted for each new patient or when scale has been majorly adjusted
34
What happens when you overgain?
Bleeding
35
What happens when you undergain?
Missing data
36
What are some tips for adjusting scale for colour images?
Assess flow type
1. average velocity
2. High Velocity
3. Low Velocity
37
What should the scale be set for average velocity?
Leave scale as in (50-75)
38
What should we scale for in terms of high velocity? What do we need to remember?
1. Increase scale
2. Some aliasing is normal at AV, PV, Ao
39
What should we do in terms of scale for low velocity? What are some examples?
1. Decrease scale
2. Pulmonary veins, IVS, IAS
40
What are some tips for Box size in colour doppler?
1. Box should be wide enough to cover the width of the entire valve
2. Box should be narrow enough to maintain FR
3. Box should be fairly tall
41
What should we remember to do with Box size in terms of colour imaging?
Make it long and lean!
42
What should the framerate be for colour imaging?
20 Hz+
43
What are some tips for entering in colour imaging? 2
1. Centre the subject within the colour box
2. Ensure there is some room around the subject
44
What are five ways we can make spectral adjustments?
1. Alignment
2. Baseline
3. Scale
4. Gain
5. Sweep speed
45
How should we use alignment to make spectral adjustments? 2
1. Ideal doppler angle is 0 degrees
2. Try to line up flow to be parallel wit hour beam
46
How can we use the baseline to adjust the spectral image?
Baseline should sit 1/4 - 1/3 from either the top or bottom, leaving room for dominant flow patter
47
How should we adjust scale to adjust spectral image?
1. Scale low enough for no wasted space
2. Scale high enough to leave room around signal
*waveform should occupy >50% of the available space*
48
How do we use gain to adjust for spectral imaging? 2
1. Eliminate noise from behind signal. *Background black, PW- black envelope*
2. Gain should be high enough to see signal well. *some background noise on difficult patients*
49
How can we use sweep speed for spectral adjustment?
1. Sweep speed should be set to show 3-4 full beats
2. Increase the sweep speed for higher HR
3. Decrease sweep speed for Low HR
50
Sweep speed must be optimized when?
Whenever measuring time, faster sweep speed stretches waveform out
51
Sweep speed is measured how?
Mm/sec
52
What are values we use for measuring sweep speed? 4
1. Peak velocities
2. Traces
3. Slopes
4. Times
53
When adjusting the spectral signal to assess for Tricuspid regurgitation, we want to do what?
Leave enough room below the baseline to show potential Tricuspid regurgitation
54
We assess the TV with spectral in what? (windows)
1. PLAX
2. PSAX
3. A4C
4. +/- subcostal
55
TV scale should be set to what?
240 cm/sec
56
Why is the TV scale below baseline set to 240 cm/sec
Velocity where significant TR first appears
57
In terms of spectral doppler why do we use pulsed wave? 2
1. Pulses sample from a specific site
2. Used for lower velocity signal
58
Why would we use a continuous wave for spectral doppler? 2
1. Samples entire scan line
2. Used for high velocity signals such as stenosis
59
What are some advantages for PW?
1. Range specificity
2. Adjustment of sample volume size and position
3. **Able to map velocities at any point in the heart**
4. 2D display guidance
60
What disadvantages of PW? 2
1. Inability to measure high velocities (>2.0 - 2.5 m/s) due to aliasing
2. PW doppler is limited by speed of sound in tissue and PRF
61
What are some limitations of PW limitations? What happens when we exceed limitations? 3
1. Nyquist limit
2. Nyquist is around 1/2 PRF
3. Aliasing occurs if the Nyquist limit is exceeded
62
How do we overcome PW doppler limitations? 4
1. Adjust baseline
2. Decrease the sample depth (Increase PRF)
3. Increase the PRF by increasing the number of sample volumes
4. Switch to CW doppler?
63
In terms of increasing the PRF by increasing the number of sample volumes, how would we do this?
1. 2nd pulse emitted before the 1st returns
2. Leads to range ambiguity
64
What is CW doppler?
2 crystal transducer. One that transmits and one that receives
65
What is the advantage of CW?
High velocity range
66
What is the main disadvantage of CW?
No range resolution. Unable to be sure that a velocity is coming from a specific location
67
What does tissue doppler imaging (TDI/ DTI) do? What are some benefits? What principles does it use?
1. Uses the same principles as blood flow
2. Assessing the movement of myocardial tissue
3. TDI signal is of greater intensity (bright)
4. Lower velocity as compared to blood flow velocities
68
TDI should resemebe a mirr image of what?
MV velocity profile and on a lower scale
69
The machine is able to change settings to automatically to do what for TDI?
Optimize tissue doppler waveforms
70
For TDI Filters are set how?
1. Filters set to exclude high velocities
2. Filters set to exclude weak reflectors
3. May need increase gain on Philips machines
71
Advantages of TDI?
1. Easily reproducible
2. Provides both systolic and diastolic information in one waveform
3. Can be performed on every patient including TDS patients
4. **Less volume dependent than MV inflow**
72
What are some disadvantages of TDI?
1. Angle dependent
2. Filter settings can vary widely between vendors
3. Gain settings can be too low on Philips
4. Not helpful when patient has prosthetic valves, mitral annular calcification, and mitral annular ring
73
How to turn on TDI?
1. Click the TDI button on the touch screen
2. Place your cursor at the annulus
3. Turn on PW
74
What are the two common measurements used for doppler?
1. Peak velocity
2. Velocity time integral (VTI)
75
What does peak velocity measure in basic doppler? What can it be done on? And what we do not include?
1. Peak velocity
2. Maximum peak instantaneous pressure gradient
3. Can be done on any valve inflow or regurgitation
4. Do not include the feathering when performing the measurement
76
For measuring peak instantaneous pressure gradient the higher the pressure gradient between the two chambers what happens?
The higher the velocity
77
What are some measures we use for Velocity time integral? 5
1. Peak velocity (m/s)
2. Mean velocity (m/s)
3. VTI (CM)
4. Max PG (mmHG)
5. Mean PG (mmHg)
78
How do we measure the “chin” in terms of Jet overestimation?
Measure the Max TR jet vel at the strongest, signals “modal velocity”
79
What is the “beard” for jet overestimation?
Instrincic spectral broadening will result in an overestimation of TR and therefore the RVSP
80
What will we use the bernoulli principle to measure in echo?
Measure pressure gradients
81
What are some limitations of pressure gradient estimations?
1. Can be underestimated by non- parallel sampling of blood flow
2. Doppler derived pressures are not a direct match with in vastly derived pressures
3. Should measure 3-5 beats when arrhythmias are present
82
Echo values are slightly higher than what?
Cath labs
83
Pressure gradient estimations should measure 3-5 beats when arrhythmias are present especially when?
Atrial fibrillation where velocities will be averaged
84
Pressure gradients may be underestimated due to what?
1. Incorrect doppler angles <20
2. Viscous friction from blood hitting walls
3. Increased proximal velocity >1.2 m/sec
85
When we have a incorrect doppler angle <20 degrees what happens?
1. A 20 degree offset flow direction = 6% underestimation of blood flow velocity
2. When factored into the Bernoulli equation, the error will be much inherent because we square the velocity
86
When would viscous friction from blood hitting walls be an underestimation of pressure gradients?
1. When a stenosis is > 10mm in length
2. Eccentric regurgitation wall jets
87
What are some measurements we take for RVSP and Bernoulli principle? 3
1. TR max velocity
2. IVC diameter
3. IVC collapse %
88
What is the systolic pressure in the PA equal to?
Systolic pressure in the RV assuming there is no blockage in the outflow
89
Systolic pulmonary artery pressure = what?
Right ventricular systolic pressure
**SPAP = RVSP**
90
TR pressure gradient is the difference between what?
The RV and RA pressures during systole
91
TR pressure is the difference between the RV and RA pressures during systole. We can calculate this using what Bernoulli formula?
92
If we want to know the pressure in the RV, we must do what?
Add the pressure in the RA to the TR pressure gradient
93
What is the Bernoulli principle? And what is the normal RVSP?
94
How do we calculate AVA?
CSA x (LVOT.VTI/AV.VTI)
CSA = 0.785 X LVOT^2
