Arterial Physiology & Fluid Dynamics

Question 1

the arterial system pumps ~ ___ ml of blood into the aorta with every heartbeat

Answer 1

~70ml

Question 2

what is stroke volume?

Answer 2

amount of blood ejected

Question 3

blood moves from regions of ___ to ___ energy

Answer 3

high to low energy

Question 4

what 3 types of energy are there in the vascular system?

Answer 4

kinetic
potential
gravitational

Question 5

what is the formula for kinetic energy?

Answer 5

KE = 1/2mv²

Question 6

what is the formula for potential energy?

Answer 6

PE = mgh

Question 7

two types of laminar flow

Answer 7

parabolic flow
plug flow

Question 8

describe parabolic flow

Answer 8

highest velocity is in the center of the lumen

Question 9

describe plug flow

Answer 9

blood travels at the same velocity throughout the lumen

Question 10

what is viscosity?

Answer 10

thickness of fluid

Question 11

↑ viscosity causes ↓ ____

Answer 11

↑ viscosity ↓ velocity

Question 12

___ of the vessel has an even more dramatic effect on flow resistance

Answer 12

diameter

Question 13

what is the equation for flow resistance?

Answer 13

R = 8ηL / πr⁴

η = fluid viscosity
L = length
r = radius

Question 14

what is the equation for Poiseuille’s Law?

Answer 14

Q = (P1 - P2)πr⁴ / 8ηL

P1 = pressure at the proximal end
P2 = pressure at the distal end
r = radius
η = fluid viscosity
L = length

Question 15

what is the equation for Reynolds Number?

Answer 15

Re = Vp2r / η

V = velocity
r = radius
p = density of fluid
η = fluid viscosity

Question 16

Re > 2000

Answer 16

turbulent flow

Question 17

turbulent flow may cause the vessel walls to vibrate which is called a ___

Answer 17

bruit

Question 18

what is Bernoulli’s Principle?

Answer 18

velocity and pressure are inversely related

Question 19

flow separations are caused by changes in (2)

Answer 19

geometry of the vessel
direction of the vessel

Question 20

flow seperations help define whether an image is in systole or diastole, during ___ the flow at the vessel wall is stagnant

Answer 20

diastole = stagnant

Question 21

Answer 21

A = early systole
B = peak systole - aorta walls distend, storing PE
C = late systole - temporary flow reversal
D = early diastole
E = late diastole - vessels recoil, converting PE to KE

Question 22

unilateral flow alterations suggest ___ and/or ___

Answer 22

vessel disease and/or extrinsic compression

Question 23

bilateral flow alterations suggest ___

Answer 23

cardiac involvement

Question 24

stenosis of the aortic valve causes (2)

Answer 24

delay in systolic upstroke
decrease PSVs

Question 25

regurgitation/insufficiency of the aortic valve cause (2)

Answer 25

double systolic peak (pulsus bisferiens)
diminished diastolic flow or reverse flow

Question 26

high cardiac output may be evident in ____

Answer 26

younger athletes

Question 27

high cardiac output may be related to ___

Answer 27

noncardiac source (anemia)

Question 28

low cardiac output

unilateral - suspect ___
bilateral - extreme case of ___

Answer 28

unilateral - suspect severe proximal occlusive disease
bilateral - extreme case of cardiomyopathy

Question 29

intra-aortic balloon pump provides temporary assistance with left ventricular contraction by ___

Answer 29

decreasing afterload

Question 30

intra-aortic balloon pump increases ___ in cases of low cardiac output or cardiac instability

Answer 30

increases coronary artery blood flow

Question 31

intra-aortic balloon pump is placed in the thoracic aorta via ___

Answer 31

superficial artery

Question 32

intra-aortic balloon pump is inflated during ___ which increases aortic pressure and coronary artery blood flow

Answer 32

diastole

Question 33

intra-aortic balloon pump is deflated during ___

Answer 33

left ventricular ejection

Question 34

ventricular assist device (VAD) assist weakened ventricles by ___

Answer 34

mechanically pumping blood out of the heart

Question 35

what is LVAD?

Answer 35

continuous flow pump (most commonly used)

Question 36

what is BiVAD?

Answer 36

pulsatile flow pump that assists both ventricles

Question 37

what is the most common finding suggestive of a cardiac abnormality?

Answer 37

pulsatile venous Doppler in the lower extremity

Question 38

what is the best vasodilator of high resistance vessels?

Answer 38

exercise

Question 39

exercise decreases ___ of the Doppler signal

Answer 39

decreases flow reversal

Question 40

stenosis causes a major reduction in (2)

Answer 40

volume flow
pressure

Question 41

stenosis is significant when the cross-sectional area of the arterial lumen is reduced ___% which corresponds to a diameter reduction of ___%

Answer 41

cross-sectional area reduction 75% = diameter reduction 50%

Question 42

true or false: 2 or more stenotic lesions that occur in series have a greater effect on volume flow and distal pressure than a single lesion of equal total length

Answer 42

true

Question 43

if there are stenoses in two different. vessels that are parallel, the overall resistance to flow is ___ than the resistance in each individual stenosis

Answer 43

less

Question 44

velocities usually dampen ___ to stenosis

Answer 44

proximal

Question 45

the increased range of Doppler frequency shift frequencies is displayed as ___

Answer 45

spectral broadening

Question 46

___ turbulence is usually seen with stenosis

Answer 46

poststenotic turbulence