Hemodynamics

Question 1

Factors that affect Blood flow volume?

Answer 1

Pressure Gradient, Tube Radius, Tube Length, & Blood Viscosity

Question 2

The factors that affect Blood flow volume are expressed how?

Answer 2

Poiseuille’s Law

Question 3

Poiseuille’s Law

Answer 3

States that flow volume varies directly with the pressure gradient and the 4th power of the radius of the tube, & flow varies inversely with the length of the tube & viscosity of the fluid

Question 4

As pressure gradient increases

Answer 4

flow volume increases

Question 5

As tube diameter or radius increases

Answer 5

flow volume increases

Question 6

As length of the tube increases

Answer 6

flow volume decreases

Question 7

As fluid viscosity increases

Answer 7

flow volume decreases

Question 8

What has the greatest effect or influence on the flow volume and flow resistance?

Answer 8

Tube diameter or radius, because it is to the 4th power

Question 9

What will increase resistance of flow?

Answer 9

An increase in Fluid viscosity and or tube length

Question 10

What determines how blood moves in the heart?

Answer 10

Blood moves from an area of high pressure to area of low pressure

Question 11

Average pressures in each chamber(diastole/systole)

Answer 11

RA:5/5, RV:5/25,
LA:10/10, LV:10/120,
PA:10/25, AO:80/120

Question 12

Pressure Gradient

Answer 12

Difference in pressure on either side of a valve

Question 13

Describe the normal PG between atria & ventricle during diastole? During systole?

Answer 13

Low PG during diastole.

High PG during systole.

Question 14

Describe the normal PG between great arteries and ventricles during systole? During diastole?

Answer 14

Low PG during systole.

High PG during diastole.

Question 15

What does low PG do?

Answer 15

Allow blood flow

Question 16

What does high PG do?

Answer 16

Keeps valves shut

Question 17

Five types of steady flow?

Answer 17

Inlet(Plug), Laminar, Parabolic, Disturbed, Turbulent

Question 18

What is Inlet(plug) flow?

Answer 18

All velocities are equal at all radical distances from the center of the tube. usually located at the entrance of a great vessel(AOV or PV)

Question 19

What is Laminar flow?

Answer 19

When fluid particle motion becomes smooth and parallel to each other. Fully developed laminar flow becomes parabolic in shape.

Question 20

What is Disturbed flow?

Answer 20

Occurs at an area of stenosis or vessel bifurcation where fluid particles still flow in a forward direction but have been disturbed

Question 21

What are the types of laminar flow?

Answer 21

Inlet(plug), parabolic, and disturbed flow

Question 22

What is Turbulent flow?

Answer 22

Occurs when fluid particles move in multiple directions and different velocities and is considered abnormal flow. Turbulent flow net direction of flow is forward.

Question 23

What is a Vortices?

Answer 23

Fluid with whirling or circular motion and may develop where blood becomes turbulent

Question 24

What is a Eddi flow?

Answer 24

small circular currents may develop where blood becomes turbulent

Question 25

What predicts Turbulent flow?

Answer 25

Reynolds number greater than 2000

Question 26

When turbulent flow is present what happens to the PG?

Answer 26

It increases rapidly

Question 27

Bernoulli equation states what?

Answer 27

There will be an increase in velocity(kinetic energy) with a decrease in pressure(potential energy) at the site of an obstruction to flow. An inverse relationship

Question 28

Bernoulli based on what?

Answer 28

Conservation of energy principle which says that if there is a change in one of these energies, potential(pressure), kinetic(velolcity), or gravitational energy there will be a change in the other energies to maintain the same level of total energy.

Question 29

Simplified Bernoulli equation?

Answer 29

P=4(Vsquared)

Question 30

In clinical imaging ultrasound

Answer 30

proximal velocity, flow acceleration and viscous friction are ignored

Question 31

Pitfalls of Bernoulli equation?

Answer 31

* If proximal velocity is greater than 1.0m/s (PG may be overestimated) * Stenosis in a series (coronary artery disease, or tunnel like stenosis (coarctation,prosthetic heart valves),=PG will be too low due to ignoring viscous friction

Question 32

Why do you estimate PG from transvalvular velocity?

Answer 32

To assess severity of stenosis

Question 33

Echo is?

Answer 33

Non-invasive, low risk, reproducible, lower cost than heart cath and the method of choice in evaluation of valvular heart diseases

Question 34

Heart Catherization

Answer 34

Gold Standard

Question 35

Valvular Stenosis

Answer 35

Causes a reduced orifice

Question 36

How do we evaluate valvular stenosis?

Answer 36

2D, color flow, and spectral doppler

Question 37

Valvular Stenosis causes a pressure overload where?

Answer 37

Chamber proximal to the obstruction and turbulent flow distal to it.

Question 38

AS/PS Where does pressure increase?

Answer 38

Ventricles

Question 39

MS/TS Where does pressure increase?

Answer 39

Atrias

Question 40

AS/PS What is the effect on velocity through the valve?

Answer 40

Increases with abnormal flow, and will have lower pressure

Question 41

AS/PS What is the effect on the chamber?

Answer 41

Hypertrophy, enlarged & thickened like a larger muscle, pressure has increased with the abnormal flow, and will have a lower velocity

Question 42

MS/TS What is effect on the velocity through the valve?

Answer 42

Increases with abnormal flow, will have lower pressure

Question 43

MS/TS What is the effect on the chamber?

Answer 43

Atria dilate and stretch (like a balloon) because of increased pressure. Pressure lowers at stenosis, and normalizes distal to stenosis

Question 44

Which part of the stenosis is the velocity the highest?

Answer 44

The narrowest part of the stenosis, pressure lower

Question 45

Which part of the stenosis is the pressure the highest?

Answer 45

Proximal to the stenosis

Question 46

With regurgitation, the abnormal flow (turbulent flow) results will be?

Answer 46

Volume overload, chamber dilation, can have pressure overload and volume overload together