Week 3 - Lesson 1 (Part 6)

Question 1

What is blood pressure effect by? (2)

Answer 1

1. Peripheral resistance

2. Blood vessel elasticity

Question 2

What does a healthy artery do? (4)

Answer 2

1. Expands
2. Absorbs the shock of systolic pressure
   - each instant that the left ventricle contracts and forces a large bolus of blood into the system
3. Elastic recoil of the vessel
4. Maintains the continued flow of blood during diastole

Question 3

What happens to an individual that has arteriosclerosis? (2)

Answer 3

1. Arteries become calcified and rigid
   - so they can’t expand when the pulse wave of systolic pressure passes through them
2. The walls of the arteries experience higher pressures and become weaker and weaker

Question 4

Where does atheroma develop?

Answer 4

In the arteries

Question 5

What does atheroma do?

Answer 5

Impeds the flow of blood

Question 6

How can you confirm atheroma?

Answer 6

Spectral doppler analysis

- depends on the extent of atheroma present and on the degree of obstruction

Question 7

What kind of flow does a vessel have when flow enters it?

Answer 7

Plug flow

Question 8

Plug flow

Answer 8

No leaders in velocity

- all at the same time

Question 9

What happens to the flow pattern of blood as it moves along the normal straight unobstructed tube?

Answer 9

It becomes parabolic

- laminar (normal flow)

Question 10

Where is the flow the highest/lowest in laminar flow? (2)

Answer 10

1. Highest = in the centre

2. Lowest = at the walls

Question 11

What is laminal flow determined by? (2)

Answer 11

1. Frictional fouces
2. Inertial forces

• between the layers of blood and changes throughout the pulse cycle

Question 12

What kind of velocity for laminar flow have?

Answer 12

Low

Question 13

What happens to the blood flow as the pressure wave propagates? (2)

Answer 13

1. Flow begins as a result of high pressure to low pressure gradient
2. Blood velocity increases uniformly across the vessel in early systole as fluid motion begins

Question 14

What kind of velocity does turbulent flow have?

Answer 14

High

Question 15

Turbulent flow (4)

Answer 15

1. Abnormal flow
2. Particular elements no longer travel along well-defined paths
3. Random component to the motion of the fluid
4. Significant irreversible loss of energy occurs

Question 16

What are 2 essential flow states?

Answer 16

1. Laminar

2. Turbulent

Question 17

Disturbed flow

Answer 17

Is flow that is somewhere between laminar and turbulent flow

Question 18

What is an example of disturbed flow?

Answer 18

The separation of flow that occurs in vessels with an obvious change in lumen size
- eg. the carotid bulb

Question 19

What is the velocity in disturbed flow?

Answer 19

Will be more random and display itself as spectral broadening, but will not show an increase in velocity in a normal vessel

Question 20

What is disturbed flow often an indication of?

Answer 20

Pathological change in the vessel

Question 21

Where does disturbed flow occur? (4)

Answer 21

1. Arterial dilatation
2. Curvature
3. Branching
4. Bifurcation

Question 22

What does turbulent flow create?

Answer 22

Eddy’s

- swirling

Question 23

What does a clean signal look like on US? (6)

Answer 23

1. Clean up stroke
2. Low resistance
3. Low flow
4. Clean anechoic window
5. Free floating above the base line
6. Bright

Question 24

What does a abnormal spectral broadening look like on US? (5)

Answer 24

1. Turbulent flow
2. Window is filled in
3. Little bit below the baseline
4. High pitch sound
5. Aliasing

Question 25

Where does turbulent flow mostly occur?

Answer 25

After a stenosis

- but some happen at the stenosis

Question 26

Where does disturbed and turbulent flow occur?

Answer 26

In post stenotic regions

Question 27

What does disturbed and turbulent flow give rise to?

Answer 27

Spectral broadening

Question 28

Critical stenosis

Answer 28

Narrowing of the arterial lumen resulting in a hemodynamically significant reduction in volume, pressure and flow

Question 29

What happens to pressure right before a stenosis?

Answer 29

It decreases

Question 30

Why does pressure decrease before a stenosis?

Answer 30

In order to allow fluid to accelerate into the stenosis and decelerate out of it

Question 31

What is the magnitude of blood cells dependent on?

Answer 31

The degree of the stenosis

Question 32

Where is arterial pressure higher/lower? (2)

Answer 32

1. Higher = proximal to the site of narrowing

2. Lower = distally to the site of narrowing

Question 33

What is arterial pressure reduction distally accompanied by?

Answer 33

A loss of kinetic energy distal to the stenosis

Question 34

What is the result of a disease progression?

Answer 34

Further loss of energy and pressure, which results in increased vasodilation

Question 35

Mild turbulent

Answer 35

Little bit of filling, turbulence, not alot of change

Question 36

Critical turbulent

Answer 36

Pressure decreases and velocity increases