Key Terms

Question 1

Hemodynamics

Answer 1

study of blood moving through the circulatory system

Question 2

Flow

Answer 2

indicates the volume of blood moving during a particular time

Question 3

Velocity

Answer 3

indicates the speed or swiftness of a fluid moving from one location to another

Question 4

Laminar vs. turbulentLaminar

Answer 4

when the flow streamlines are aligned and parallel

Question 5

Laminar vs. turbulentTurbulent

Answer 5

chaotic flow patterns in many different directions and at many speeds

Question 6

Reynolds number

Answer 6

predicts whether flow is laminar or turbulent, unit less number

Question 7

Forms of energy

Answer 7

kinetic, pressure, and gravitational

Question 8

Energy losses in circulation

Answer 8

viscous loss, frictional loss, and inertial loss

Question 9

Stenosis

Answer 9

narrowing in the lumen of a vessel

Question 10

Bernoulli’s principle:

Answer 10

relationship between velocity and pressure in a moving fluid

Question 11

Ohm’s law

Answer 11

pressure gradient = flow x resistance

Question 12

Venous hemodynamics

Answer 12

normal function = low pressure, partially filled with blood and only partial expanded

Question 13

Hydrostatic pressure

Answer 13

pressure related to the weight of blood pressing on a vessel measured at a height above or below heart level

Question 14

Doppler frequency

Answer 14

the change in frequency

Question 15

Frequency shift

Answer 15

created when transmitted sound waves strike moving red blood cells

Question 16

Speed vs. velocitySpeed

Answer 16

purely magnitude, indicates the distance that red blood cells moves in 1 second

Question 17

Speed vs. velocityVelocity

Answer 17

defined by a magnitude and a direction, length of arrow indicates magnitude and angle indicates direction

Question 18

Doppler equation

Answer 18

Doppler shift = 2 x velocity x transducer frequency x cos / propagation speed

Question 19

Sound beam direction vs. flow direction

Answer 19

Doppler shift represents 100% of true velocity when blood flow is parallel to sound beam. When there is an angle, Doppler measures less than the true velocity

Question 20

Bidirectional Doppler

Answer 20

distinguish the flow to and away from transducer, positive toward, negative away

Question 21

Continuous wave Doppler

Answer 21

two crystals, one constantly transmits and one constantly receives

Question 22

Pulsed wave Doppler

Answer 22

one pzt is necessary, alternated between sending and receiving sound pulses

Question 23

Aliasing

Answer 23

22. Aliasing: false: identity, high velocity in one direction are incorrect, flow above baseline, bottom part of spectrum

Question 24

Nyquist limit

Answer 24

high Doppler frequency or velocity that can be measuring without the appearance of aliasing, top of spectrum

Question 25

Gray shades of a spectrum

Answer 25

related to amplitude of reflected sound or number of blood cells creating the reflection

Question 26

Color flow Doppler

Answer 26

measure mean velocity, is pulsed technique, range resolution, and subject to aliasing

Question 27

Color maps

Answer 27

convert measured velocities into colors that appear on the image

Question 28

Doppler packets

Answer 28

multiple ultrasounds pulses are used to accurately determine blood velocities

Question 29

Power Doppler

Answer 29

only identifies the presence of a Doppler shift, doesn’t evaluate speed or direction

Question 30

Spectral analysis

Answer 30

tools that breaks the complex signal into tis basic “building blocks” and identifies the individual velocities that make up reflected Doppler signal

Question 31

FFT

Answer 31

digital technique, is used to process both pulsed and continuous wave Doppler signals

Question 32

Autocorrelation

Answer 32

digital technique used to analyze color flow Doppler

Question 33

Wall filter

Answer 33

removes the color form slowly moving reflectors such as blood cells and vibrating tissue