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Hemodynamics > Hemodynamics > Flashcards

Hemodynamics Flashcards

1
Q

Factors that affect Blood flow volume?

A

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

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2
Q

The factors that affect Blood flow volume are expressed how?

A

Poiseuille’s Law

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3
Q

Poiseuille’s Law

A

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

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4
Q

As pressure gradient increases

A

flow volume increases

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5
Q

As tube diameter or radius increases

A

flow volume increases

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6
Q

As length of the tube increases

A

flow volume decreases

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7
Q

As fluid viscosity increases

A

flow volume decreases

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8
Q

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

A

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

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9
Q

What will increase resistance of flow?

A

An increase in Fluid viscosity and or tube length

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10
Q

What determines how blood moves in the heart?

A

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

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11
Q

Average pressures in each chamber(diastole/systole)

A

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

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12
Q

Pressure Gradient

A

Difference in pressure on either side of a valve

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13
Q

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

A

Low PG during diastole.

High PG during systole.

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14
Q

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

A

Low PG during systole.

High PG during diastole.

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15
Q

What does low PG do?

A

Allow blood flow

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16
Q

What does high PG do?

A

Keeps valves shut

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17
Q

Five types of steady flow?

A

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

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18
Q

What is Inlet(plug) flow?

A

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)

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19
Q

What is Laminar flow?

A

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

20
Q

What is Disturbed flow?

A

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

21
Q

What are the types of laminar flow?

A

Inlet(plug), parabolic, and disturbed flow

22
Q

What is Turbulent flow?

A

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

23
Q

What is a Vortices?

A

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

24
Q

What is a Eddi flow?

A

small circular currents may develop where blood becomes turbulent

25
Q

What predicts Turbulent flow?

A

Reynolds number greater than 2000

26
Q

When turbulent flow is present what happens to the PG?

A

It increases rapidly

27
Q

Bernoulli equation states what?

A

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

28
Q

Bernoulli based on what?

A

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.

29
Q

Simplified Bernoulli equation?

A

P=4(Vsquared)

30
Q

In clinical imaging ultrasound

A

proximal velocity, flow acceleration and viscous friction are ignored

31
Q

Pitfalls of Bernoulli equation?

A
  • 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
32
Q

Why do you estimate PG from transvalvular velocity?

A

To assess severity of stenosis

33
Q

Echo is?

A

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

34
Q

Heart Catherization

A

Gold Standard

35
Q

Valvular Stenosis

A

Causes a reduced orifice

36
Q

How do we evaluate valvular stenosis?

A

2D, color flow, and spectral doppler

37
Q

Valvular Stenosis causes a pressure overload where?

A

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

38
Q

AS/PS Where does pressure increase?

A

Ventricles

39
Q

MS/TS Where does pressure increase?

A

Atrias

40
Q

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

A

Increases with abnormal flow, and will have lower pressure

41
Q

AS/PS What is the effect on the chamber?

A

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

42
Q

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

A

Increases with abnormal flow, will have lower pressure

43
Q

MS/TS What is the effect on the chamber?

A

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

44
Q

Which part of the stenosis is the velocity the highest?

A

The narrowest part of the stenosis, pressure lower

45
Q

Which part of the stenosis is the pressure the highest?

A

Proximal to the stenosis

46
Q

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

A

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

Hemodynamics (1 decks)

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