# Physics Lecture #4 Flashcards

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1
Q

Vertical axis

A

Increasing frequency shifts/velocity towards and away from the transducer

2
Q

Horizontal axis

A

Since the transmitting of Doppler lines is repeated fro a period of at least a cardiac cycle, the variation of the Doppler spectrum with time is presented on horizontal axis

3
Q

Third Axis

A

Corresponds to amplitude of strength of the signal

4
Q

For a fixed location

A

varying spectral signal intensities are generally related to the number of reflecting RBC (Greater numbers of RBC have greater reflectivity)

5
Q

Systolic acceleration and pressure

A

The sharp upstroke of a normal pressure waveform represents the rapid rise in pressure during systole (heart cycle)
A rapid increase in pressure should result in a rapid increase in volume
As pressure increases, the volume increase

6
Q

As systolic pressure increases

A

Volume increases

7
Q

Normal flow

A

Rapid increase in pressure should result in a rapid accleration

8
Q

Because the vertical axis of spectral Doppler=velocity and horizontal represents time….

A

Slope of the Doppler Spectrum represents the rate of change in velocity per time (acceleration)

9
Q

Risetime

A

Note that the change in time that it takes for a velocity to go from its minimum at the end of the diastolic flow phase to the peak systole

10
Q

Doppler Risetime

A

The acceleration of the Doppler spectrum will decrease with proximal flow reducing stenosis
This decreased acceleration is clearly the consequence of an inability for the volume to rapidly increase across the resistance/blockage of the stenosis

11
Q

How is decreased acceleration visualized

A

Longer time to reach peak velocity

12
Q

Spectral window

A

region of signal absence

13
Q

what will diminish spectral window

A

This presence of abnormal flow or turbulent flow will diminish this spectral window

14
Q

what may cause there to be no spectral window

A
```CW Doppler
Large PW sample to vessel size
-sample volume too close to the vessel wall
-overgaining of the spectrum
-Flow angle too close to 90 degrees
15
Q

Absence of a spectral window does not necessarily imply

A

A hemodynamic state of turbulence or pathological condition

16
Q

Normal arterial signal

A

multi-phasic with rapid,
(a) followed by one or more diastolic
components

17
Q

Velocity criteria

A
```Spectral Doppler provides the distribution of signals, there is more than one velocity measurement that can be correlated with disease and severity
Peak Systolic Velocity
Mean Velocity
Resistive Index
End Diastolic Velocity```
18
Q

Peak velocity

A

is the highest velocity obtained throughout the cardiac cycle

19
Q

peak systolic velocity

A

For a normal situation, flow velocity in an artery accelerates very rapidly and reaches its peak within a few hundreds of a second after ventricular contraction begins
Produces an almost vertical deflection of the Doppler waveform at the start of systole

20
Q

Mean velocity

A

The mean velocity is the average velocity registered over a cardiac cycle
It can be used in conjunction with an area measurement to calculate volumetric flow