Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

VASC 335 > Arterial Hemodynamics > Flashcards

Arterial Hemodynamics Flashcards

1
Q

What is pressure and what is it measured in?

A

The amount of force put on artery at any point in time.

Mm of mercury (mmHg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does the pressure change from the heart to the ankles?

A

Systolic increases

Diastolic decreases

Mean decreases (creates gradient)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is kinetic energy and how much does it account for?

A

2 %

Energy created by the movement of blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When does KE increase?

A

During exercise or within a stenosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is potential energy and how much does it account for?

A

98%

The main form of energy resulting from the pressure distending the vessels (stored within vessel walls).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is flow?

A

The amount of fluid travelling past a point in a given amount of time

Units = volume/time (L/min)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the density of blood and does it change?

A

1.05 g/ml

No it is constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is viscosity?

A

The resistance of a fluid in motion to flow, the amount of frictional forces as the molecules move against one another. (Thickness of a fluid).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the most important factor affecting viscosity?

A

The concentration of RBC’s (hematocrit) and plasma protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does length effect resistance?

A

A longer length of tube contains more resistance due to increased friction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does radius effect resistance?

A

As radius decreases, resistance increases to the 4th power

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is resistance?

A

The force that must be overcome for flow to happen that is created by the friction of blood against the wall.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the most influential factor affecting resistance?

A

Radius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does poiseuille’s law define?

A

The relationship between pressure, volume flow and resistance through a cylinder.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the equation for the Poiseille relationship?

A

Flow volume = (Pi x change in pressure) x r^4) divided by (8 x Length x viscosity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the abbreviated formula of Poiseuille’s law?

A

Flow volume = Pressure gradient divided by the radius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the relationship between velocity and pressure?

A

Inverse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is stroke volume?

A

The amount of blood ejected from the heart during systole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What dictates the stroke volume?

A

The arterial pressure and the peripheral resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is systolic pressure?

A

Due to increased pressure from increased volume the artery walls expand creating PE within them.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the diastolic pressure?

A

As the volume and radius decreases during diastole, pressure decreases and blood flows due to its own momentum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What allows blood to flow?

A

The pressure gradient between the LV 120 mmHg and the RA (2-6mmHg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is hydrostatic pressure?

A

The force of gravity on a column of fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Where is hydrostatic pressure the greatest?

A

In the lower portion of the body

25
Q

Where is gravitational PE the highest?

A

In the upper portion of the body (right atrium).

26
Q

How is velocity related to vessel diameter?

A

Inverse.

Velocity up = diameter down

27
Q

What type of flow is referred to as “parabolic” and why?

A

Laminar flow due to the velocity profile (normal spectral and clear window looks like a parabola).

28
Q

How does mean velocity differ from max velocity i laminar flow?

A

Mean is half of the maximum peak

29
Q

When does blunt flow occur?

A

During systole in larger vessels or arterial branch origins

30
Q

What is flow separation?

A

A NORMAL flow variation when there is a sudden widening of a vessel causing fluid layers to separate and reverse flow along the wall

31
Q

What is non-laminar flow?

A

Flow that can be both normal and abnormal where a normal velocity profile is not established for 3 cm after a disruption

32
Q

What is the flow pattern of non-laminar flow?

A

Mixed w/forward and backward components

33
Q

What is the transition zone?

A

The site of boundary layer spearation in non laminar flow where the lamina reach zero velocity while transitioning from forward to backward flow.

34
Q

Where can the transition zone be seen?

A

Carotid bifurcation and distal to a stenosis.

35
Q

What is turbulance?

A

Chaotic flow where fluid exits a tight spot and enters a wider area, fluid whirls and is much more disordered than disturbed flow.

36
Q

What is the velocity pattern of turbulence?

A

Feathered appearance with spectral broadening.

37
Q

What is does the Reynold’s number predict? An how does velocity and viscosity affect?

A

A number that predicts when turbulence will occur.

Risk of turb increases as velocity and viscosity increase

38
Q

What is the reynolds number?

A

Turbulence occurs when the Reynolds meets or exceeds 2000

39
Q

What is the flow pattern around bifurcations and branches?

A

Disturbed (larger vessel = greater disturbance)

40
Q

What is the flow pattern most common in arteries with significant disease?

A

Disturbed

41
Q

What happens to the pressure at bifurcations of normal vessels?

A

Small pressure drop

42
Q

What type of flow patter occurs in curved vessels?

A

Helical flow

43
Q

What is helical flow?

A

In a curved vessel the fluid flows faster near the walls and may reverse in the centre due to the fast flow moving outward as it enters the curve.

44
Q

Match the flow profile to the region? (4)

A

Parabolic = laminar region

Plug = laminar region

Disturbed = transition zone

Turbulent = turbulent region

45
Q

List the 4 flow profiles from low to fast velocity?

A
  1. Parabolic (lowest)
  2. Plug (lower)
  3. Disturbed (higher)
  4. Turbulent (highest)
46
Q

What does the Bernoulli principle explain?

A

The balance of energy in the movement of fluid, explains relationship between area, velocity and pressure at a stenosis.

47
Q

What happens to the velocity and pressure within a stenosis?

A

Low pressure, high velocity (inversely related) to maintain the same total energy

48
Q

What happens to the velocity and pressure distal to a stenosis?

A

Velocity decreases and pressure increases compared to IN stenosis but not proximal to it.

49
Q

What is the profile proximal to a stenosis?

A
  • Increased pulsatility (high resistance = peaks)
  • Narrow sharp peak
  • Low peak systolic velocity
  • Laminar flow
  • Thumping during systole
50
Q

What happens to the peak systolic velocity and end diastolic velocity through a stenotic jet?

A

PSV increases to 80% of the diameter reduction and then DECREASES.

EDV is markedly increased with greater than 70% stenosis

51
Q

What happens distal to a stenosis?

A
  • Post-stenotic turbulence
  • Dampened tardus parvus
  • Energy released as heat
  • ## Max flow disturbance is seen within 1 cm of stenosis
52
Q

How do tandem Lesions/stenosis differ from singular?

A

There is a greater loss of energy and volume than a single lesion.

53
Q

In tandem lesions/stenosis how does the energy/velocity differ between the stenosis’s?

A

The 1st stenosis will have a greater incoming energy and will produce higher velocities than the second

54
Q

What are qualities of a low resistance waveform pattern?

A

Constant forward flow in systole and diastole with a diastolic component well above the baseline

55
Q

What are the qualities of a high resistance waveform?

A
  • Sharp upstroke
  • Low to absent diastolic flow
  • More pulsitile
56
Q

What is low pulsatility?

A

Low resistance, has a broad systolic peak and forward flow through diastole

57
Q

What is moderate pulsatility?

A

Tall sharp peak and little diastolic flow

58
Q

What is high pulsatility?

A

High resistance, narrow systolic peak, flow reveral in early diastole and little/late diastolic flow.

VASC 335 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions