Doppler Review

Question 1

Define Doppler method

Answer 1

A method for detecting the direction and velocity of moving red blood cells and tissue within the heart

Question 2

What does Doppler echo include

Answer 2

Colour flow imaging

Spectral Doppler

Question 3

What is kind of Doppler is used in colour flow imaging

Answer 3

Power Doppler

Question 4

What types of Doppler are involved in spectral Doppler

Answer 4

Pulsed wave (PW)
Continuous wave Doppler (CW)
Tissue Doppler

Question 5

What is the doppler principle measuring

Answer 5

Frequency shift

Question 6

What is the doppler shift formula

Answer 6

Df = fd– f0

Question 7

F0

Answer 7

Transmitted beam frequnecy

Question 8

Fd

Answer 8

Received beam frequency

Question 9

V

Answer 9

Velocity of blood flow

Question 10

C

Answer 10

Sound speed in the medium

Question 11

What is the doppler shift formula for blood flow

Answer 11

Df = 2 x f0 x V x cos f/ C

Question 12

What is the purpose of doppler in echo

Answer 12

Detect areas of NORMAL and ABNORMAL flow
Assess systolic and diastolic function
Provide functional information

Question 13

What are the areas of abnormal flow that doppler can detect

Answer 13

Valves: stenosis/regurg
Shunts
Differentiate between tissue and areas of blood flow

Question 14

What is the functional information that doppler in echo provides

Answer 14

Flow velocity

Pressure gradient through valves

Question 15

What are the advantages of PW doppler

Answer 15

Range specificity
Adjustment of sample volume size and position
Able to map velocities at any point in the heart

Question 16

What are the disadvantages of PW doppler

Answer 16

Inability to measure high velocities (>2.0-2.5m/s) due to aliasing
Is limited by the speed of sound in tissue and PRF

Question 17

What is the main limitation of PW doppler due to

Answer 17

The NyQuil limit

Question 18

What is the Nyquist limit

Answer 18

Approximately 1/2 PRF

Question 19

When does aliasing occur

Answer 19

If the nyquist limit is exceeded

Question 20

What is doppler CW

Answer 20

2 crystal transducer

-one for transmitting, one for receiving

Question 21

What is the main advantage of CW doppler

Answer 21

High velocity range

Question 22

What is the main disadvantage for CW doppler

Answer 22

No range resolution

Question 23

Why is there no range resolution in CW doppler

Answer 23

Only maximum velocity is measured along a scan line

Unable to be sure that a velocity is coming from a specific location- can only assume

Question 24

What does TDI use the same principle as

Answer 24

Blood flow

Question 25

What does TDI measure

Answer 25

Movement of myocardial tissue

Question 26

tissue doppler signal if of what intensity

Answer 26

Greater

Question 27

When the tissue doppler signal is compared to the blood flow signal, which velocity is lower

Answer 27

Tissue doppler (e prime, s prime)

Question 28

What is the machine automatically able to change the settings on for TDI

Answer 28

Filters set to exclude high velocities | Filters set to exclude weak reflectors (blood)

Question 29

What is the pros of tissue doppler

Answer 29

Easily reproducible Provides systolic and diastolic information in one waveform Can be preformed on TDS patients Less volume (preload) dependant than MV inflow

Question 30

What are the cons of tissue doppler

Answer 30

Angle dependant E primes should be measured at end expiration Filter settings can vary widely between vendors Gain setting can be to low on certain machines Velocities will be lower than myocardium in rest of LV due to -prosthetic valves, MAC, mitral annular ring

Question 31

What does the x axis represent on doppler signal display

Answer 31

Time in seconds

Question 32

What does the y axis represent on the doppler signal display

Answer 32

Direction + velocity (m/sec or cm/s)

Question 33

What does the z axis represent in doppler signal display

Answer 33

Brightness, strength of returning echo, # of cells at a particular velocity

Question 34

What does a strong signal represent in doppler signal display

Answer 34

More cells moving at that velocity

Question 35

What does a weak signal represent on doppler signal display

Answer 35

Less cells moving at that velocity

Question 36

In spectral Doppler the velocity range is adjusted so what happens to the waveform

Answer 36

So that it occupies at least 50% of the available scale

Question 37

What does blue represent in colour doppler

Answer 37

Flow away from the probe

Question 38

What does red represent in colour doppler

Answer 38

Flow towards the probe

Question 39

What does green indicate in colour doppler

Answer 39

Turbulence

Question 40

What is colour doppler

Answer 40

A pulsed wave technique, subject to aliasing

Question 41

What happens when the colour doppler aliases

Answer 41

The flow direction becomes ambiguous

Question 42

In the heart how can the flow direction change

Answer 42

It can change within one structure during the cardiac cycle

Question 43

What does flow direction add to cardiac scanning

Answer 43

A dynamic component

Question 44

If we call flow “normal” in cardiac scanning what are we referring to

Answer 44

Directional flow during a particular portion of the cardiac cycle

Question 45

Is colour doppler effected by the nyquist limit

Answer 45

Yes

Question 46

What are the advantages of colour doppler

Answer 46

Sensitivity Region of interest Laminar vs turbulent flow

Question 47

What are the disadvantages of colour doppler

Answer 47

Aliasing | Directional ambiguity

Question 48

What does the Bernoulli equation outline

Answer 48

The relationship between velocity and pressure

Question 49

As velocity of a moving fluid increases what what happens to the pressure within the fluid

Answer 49

Decreases

Question 50

What does the drop in pressure create

Answer 50

A pressure difference between the region proximal to a narrowing and within the narrowing

Question 51

What is the simplified Bernoulli equation

Answer 51

P1-P2=4V^2

Question 52

When is the modified Bernoulli equation used

Answer 52

To assess maximum instantaneous and mean pressure gradients

Question 53

What is the maximum gradient calculated from

Answer 53

The maximum velocity

Question 54

How is the mean gradient calculated

Answer 54

By averaging the instantaneous gradients over the ejection period

Question 55

Pressure gradient estimations can be underestimated by

Answer 55

Non-parallel sampling of blood flow

Question 56

A 20 degree offset from flow direction = what

Answer 56

6% underestimation of blood flow velocity

Question 57

When the offset degree is factored into the Bernoulli equation what will happen

Answer 57

The error will be much higher because the velocity is squared

Question 58

If an arrhymia is present what must be measured for pressure gradient estimations

Answer 58

3-5 beats, they will than be averaged

Question 59

What are other factors that will underestimate the pressure gradients

Answer 59

Significant flow acceleration Viscous forces Increased proximal velocities

Question 60

Are prosthetic valves heavier than normal valves

Answer 60

Yes

Question 61

What are the different types of viscous forces

Answer 61

Long, tubular stenosis When a stenosis is >10mm in length Eccentric wall jets

Question 62

In a normal heart where there is no significant regurg or shunts, the SV through all 4 valves will be what

Answer 62

The same

Question 63

The stroke volume through a regurgitant valve will be what than through a competent valve

Answer 63

Higher

Question 64

The SV through a regurgitant valve will include what

Answer 64

The volume of the leak and the normal SV

Question 65

What is the equation for SV

Answer 65

SV(rv)= SV(cv)+ RV

Question 66

What is the equation for the regurgitant calculation

Answer 66

RF=RV/SV

Question 67

What does the Dp/Dt measure

Answer 67

``` The rise (or fall) of pressure divided by the change in time How quickly the LV can generate pressure ```

Question 68

What is the Dp/Dt most often used for

Answer 68

Assess LV global systolic function

Question 69

When is Dp/Dt only done

Answer 69

When MR is present