Physics Lecture #4

Question 1

Vertical axis

Answer 1

Increasing frequency shifts/velocity towards and away from the transducer

Question 2

Horizontal axis

Answer 2

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

Question 3

Third Axis

Answer 3

Corresponds to amplitude of strength of the signal

Question 4

For a fixed location

Answer 4

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

Question 5

Systolic acceleration and pressure

Answer 5

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

Question 6

As systolic pressure increases

Answer 6

Volume increases

Question 7

Normal flow

Answer 7

Rapid increase in pressure should result in a rapid accleration

Question 8

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

Answer 8

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

Question 9

Risetime

Answer 9

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

Question 10

Doppler Risetime

Answer 10

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

Question 11

How is decreased acceleration visualized

Answer 11

Longer time to reach peak velocity

Question 12

Spectral window

Answer 12

region of signal absence

Question 13

what will diminish spectral window

Answer 13

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

Question 14

what may cause there to be no spectral window

Answer 14

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
-spectral broadening artifact

Question 15

Absence of a spectral window does not necessarily imply

Answer 15

A hemodynamic state of turbulence or pathological condition

Question 16

Normal arterial signal

Answer 16

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

Question 17

Velocity criteria

Answer 17

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

Question 18

Peak velocity

Answer 18

is the highest velocity obtained throughout the cardiac cycle

Question 19

peak systolic velocity

Answer 19

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

Question 20

Mean velocity

Answer 20

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