Session 1 ILOs - Anatomy, Imagine and Haemodynamics

Question 1

Outline the values for the following parameters and resting conditions and during exercise:

Cardiac output
Heart rate
Stroke volume

Answer 1

Resting conditions:

Cardiac output = 5 L/min
Heart rate = 60-90 bpm
Stroke volume = 55-80 ml/beat

During exercise:

Cardiac output = 20-35 L/min
Heart rate = 150 -200 bpm
Stroke volume = 200 ml/beat

Question 2

Describe the 3 layers of the heart wall

Answer 2

Epicardium/pericardium
- Serous membrane

Myocardium
- Cardiac muscle cells (responsible for contracting)

Endocardium
- Smooth inner surface (single cell thick)

Question 3

Describe the 3 main coronary arteries

Answer 3

1. Right coronary artery

(Left coronary/main artery - branches into)

2. Circumflex artery
3. Left anterior descending artery (Widow maker)

Question 4

What happens to flow, if resistance increases

Answer 4

If resistance increases, flow decreases

Question 5

Explain laminar and turbulent flow

Answer 5

Laminar flow (typical):

• Smooth
• Silent
• Streamlined
• Maintain energy
• Typical situation in most blood vessels

Turbulent flow (atypical):

• Disorganised
• Noisy
• Energy is lost
• Due to stenosis/narrowing

Question 6

What factor of Poisuellie’s Law has the biggest effect on flow (delta P x pi x r4 / 8 x viscosity x length)

Answer 6

Radius of vessel - it is radius to the power of 4

Question 7

Below what mean arterial pressure (MAP), does organ perfusion become impaired?

Answer 7

MAP < 70 mmHg

Question 8

With turbulent flow, what are the terms for what you can feel and what you can hear?

Answer 8

Thrill = what you can feel (if palpating)
Bruit = what you can hear (if auscultating)

Question 9

Explain the stages involved in manual blood pressure taking

Answer 9

1. Increase pulse pressure
   - Occludes the brachial artery = NO FLOW = silent
2. Gradually reduce cuff pressure
   - Some blood flow but it’s TURUBLENT FLOW = can hear Korotoff sounds
   - Start of systole
3. Reduce cuff pressure further until cuff pressure < artery pressure = NORMAL FLOW = silent again
   - Start of diastole

Question 10

Write out the equations to work out the following parameters:

Pulse pressure (PP)
Mean arterial pressure (MAP) - 2 equations
Cardiac output (CO)

Answer 10

Pulse pressure (PP)
PP = SBP - DBP

Mean arterial pressure (MAP)

1. MAP = DBP + (SBP-DBP / 3) - DBP
2. MAP = CO x TPR

Cardiac output (CO)
CO = HR x SV