Hemodynamics from new textbook

Question 1

How much blood is pumped out of the heart per minute?

Answer 1

5-6L

Question 2

Equation for cardiac output?

Answer 2

CO=SVxHR

Question 3

Bernoulli’s principle:

Answer 3

Pressure and velocity have an inverse relationship

Question 4

Poiseuille’s Law

Answer 4

The higher the pressure gradient, the more flow. The more viscous the fluid, the less flow there is. The longer the tube, the more resistance and less flow

Question 5

What’s the component that’s most likely to change in Poiseuille’s Law?

Answer 5

Radius

Question 6

The more vessels there are in a parallel, the ____ the resistance

Answer 6

lower

Question 7

What is the 0 velocity at the vessel wall called?

Answer 7

Boundary layer

Question 8

What’s the most common flow found in the body?

Answer 8

Laminar

Question 9

Reynold’s #

Answer 9

Signifies turbulance. >2000

Question 10

When do you see a tardus parvus?

Answer 10

With a proximinal obstruction

Question 11

Critical stenosis is defined as:

Answer 11

Area reduction >75%

Diameter reduction >50%

Question 12

3 Ways for venous blood to return to the heart:

Answer 12

Calf muscles
Valves
Intrathoracic pressure changes

Question 13

Doppler shift:

Answer 13

change in frequency of sound caused by a moving reflector when observed by a stationary source

Question 14

What causes the Doppler shift in US?

Answer 14

RBC’s

Question 15

Strongest/most accurate DS:

Answer 15

0

Question 16

Lowest DS:

Answer 16

90

Question 17

Should you increase or decrease the Doppler angle to reduce aliasing?

Answer 17

Increase

Question 18

RI is:

Answer 18

Peripheral resistance to flow

Question 19

PI is:

Answer 19

how dampened a waveform is

Question 20

RI formula:

Answer 20

PSV-EDV/PSV

Question 21

PI formula:

Answer 21

PSV-EDV/mean velocity

Question 22

What is the most common gray scale artifact? How can it be fixed?

Answer 22

Reverb

THI

Question 23

What vessel are we likely to see color Doppler mirroring?

Answer 23

SCA

Question 24

You see a color bruit (color pixels present in soft tissue). What could be causing it?

Answer 24

Commonly occurs as a result of a stenosis in a nearby vessel, causing a thrill in the adjacent tissue

Question 25

Monophasic flow in a resting lower extremity artery ...

Answer 25

Indicates dilatation in the distal arterioles, which can be indicative of moderate to severe disease

Question 26

In the venous circulation, which of the following is the only variable of hydrostatic pressure? Height, gravity, density or viscosity

Answer 26

Height (only variable in the equation) | ????What about gravity

Question 27

Ohm's law is analogous to Poiseuille's law, where current is represented by:

Answer 27

Ohm’s law (I = V/R) is analogous to Poiseuille’s law (Q = ΔP/R). Pressure is represented by voltage, flow is current, and resistance is the same for both

Question 28

What is the Ohm's law equation:

Answer 28

I=V/R

Question 29

Which of the following is representative of normal lower extremity peripheral venous flow? (A) Pulsatile flow (B) Respiratory phasicity (C) High transmural pressure (D) Nonspontaneous flow

Answer 29

Lower extremity peripheral venous flow should be spontaneous, have respiratory phasicity, be noncontinuous, and be nonpulsatile. Veins typically have low transmural pressure, and will appear elliptical when supine due to the increased pressure outside the vessel compared to the pressure inside the vessel.

Question 30

Rayleigh scatters:

Answer 30

Scatter to the fourth power of the frequency

Question 31

A sonographer switches to a higher frequency transducer. What effect will that have on aliasing?

Answer 31

Increased risk of aliasing. Freq shift is directly related to operating frequency. The higher the frequency shift, the greater the risk for aliasing.

Question 32

FFT

Answer 32

Spectral Doppler

Question 33

Autocorrelation

Answer 33

Color Doppler

Question 34

The higher the ensemble length (packet size)...

Answer 34

the better the ability to document slow flow and the more accurate the measured mean velocities. Tradeoff is a worse frame rate

Question 35

Aliasing occurs for which of the following reasons? (A) The velocities are too low (B) The PRF is too high (C) The sampling rate is too slow (D) The sampling rate is too high

Answer 35

C

Question 36

Increasing the pulse repetition frequency (A) Decreases the number of cycles in a pulse (B) Decreases the number of pulses per second (C) Increases the imaging depth (D) Increases the measurable frequency shift

Answer 36

D

Question 37

more accurately measure acceleration time. Which control needs to be adjusted so the waveform can be stretched out to permit a more accurate measurement? (A) Doppler gate (B) Scale (C) Wall filter (D) Sweep speed

Answer 37

D

Question 38

What angle to flow is the most accurate? (A) 0 degrees (B) 90 degrees (C) 60 degrees (D) 15 degrees

Answer 38

0

Question 39

What is the most optimal angle for 2D, gray scale imaging? (A) 0 degrees (B) 90 degrees (C) 60 degrees (D) 15 degrees

Answer 39

B

Question 40

How many samples per cycle to avoid aliasing?

Answer 40

2-3

Question 41

When must angle correction be used in spectral Doppler? (A) At all times (B) Any time continuous-wave Doppler is used (C) Whenever arterial flow is measured (D) When velocity information is needed

Answer 41

D. Angle correction is possible with PW spectral Doppler. Angle correction permits peak systolic and end diastolic flow velocities to be measured. Angle correction is not limited to arterial flow, as there are some studies where venous velocities need to be measured. Angle correction is not possible with CW Doppler.

Question 42

Which of the following is directly related to the amplitude of the Doppler shift? (A) The Doppler angle (B) The operating frequency (C) The velocity of flow (D) The number of red blood cells present

Answer 42

D

Question 43

Which setting can be adjusted to permit color Doppler twinkling artifact as an aide in identifying small calcifications? (A) Scale (B) Frequency (C) Priority (D) Persistence

Answer 43

C -- allows color pixels to replace grayscale pixels (or vice versa) as selected by the operator

Question 44

Which of the following is a constant and does not change in a nonhemodynamically significant stenosis? (A) Area (B) Velocity (C) Flow (D) Pressure

Answer 44

(C) Flow is a constant and does not change in a nonhemodynamically significant stenosis.