Pathophysiology of ischaemia and infraction (part 1)

Question 1

Define ischaemia?

Answer 1

relative lack of blood supply to tissue/organ leading to inadequate O2 supply to meet needs of tissue/organ: hypoxia

Question 2

What is hypoxic?

Answer 2

a) low inspired O2 level

b) normal inspired O2 but low PaO2

Question 3

What is anaemic?

Answer 3

normal inspired O2 but blood abnormal

not enough haemoglobin to carry oxygen

Question 4

What are the 4 types of hypoxia?

Answer 4

hypoxic

anaemic

stagnant

cytotoxic

Question 5

What is stagnant hypoxia?

Answer 5

normal inspired O2 but abnormal delivery

Question 6

What are 2 types of stagnant hypoxia?

Answer 6

local e.g. occlusion of vessel

systemic e.g. shock

Question 7

What is cytotoxic hypoxia?

Answer 7

normal inspired O2 but abnormal at tissue level

tissue cannot use oxygen that is being delivered to it

Question 8

What factors effect oxygen supply?

Answer 8

inspired O2

pulmonary function

blood constituents

blood flow

integrity of vasculature

tissue mechanisms

Question 9

What are 2 factors affecting oxygen demand?

Answer 9

1. tissue itself - different tissues have different requirements
2. activity of tissue above baseline value

Question 10

What are examples of supply issues in ischaemic HD?

Answer 10

coronary artery atheroma

cardiac failure (flow)

pulmonary function - other disease or pulmonary oedema (LVF)

Anaemia

previous MI

Question 11

What does it mean that the heart has a high intrinsic demand?

Answer 11

the control of the hearts output/ contraction force

increase cardiac output

Question 12

What is atheroma/ atherosclerosis?

Answer 12

localized accumulation of lipid and fibrous tissue in intima of arteries

Question 13

What is the clinical correlation of established atheroma in a cornionary artery?

Answer 13

stable angina

Question 14

What is the clinical correlation of complicated atheroma in coronary artery?

Answer 14

unstable angina

Question 15

What is angina?

Answer 15

when the coronary arteries receive not a sufficient blood supply

Question 16

What are the clinical manifestations of stable angina?

Answer 16

pain on exertion but not at rest

Question 17

When does a complicated atheroma in coronary artery occur?

Answer 17

something has happened to the atheroma, hemorrhage or plaque rupture

Question 18

What happens if the plaque ulcerates of fissures?

Answer 18

thrombosis –> ischemia/infarction

Question 19

What is the clinical consideration of atheroma in the aorta?

Answer 19

aneurysm

Question 20

What is infarction?

Answer 20

lecture definition:
ischemic necrosis within a tissue/organ in living body produced by occlusion of either the arterial supply or venous drainage

death of tissue as a result of failure of blood supply

commonly due to obstruction of blood vessel by a atheroma or narrow of vessel channel

Question 21

List 6 clinical consequences of atheroma/ischemia?

Answer 21

MI

TIA (transient ischemic attack)

cerebral infarction

abdominal aortic aneurysm

peripheral vascular disease

cardiac failure

Question 22

Put these terms in order of events

• MI
• coronary artery disease
• cardiac failure

Answer 22

coronary artery disease

MI

cardiac failure

Question 23

What can a change in the vessel wall cause? (Virchow’s triad)

Answer 23

thrombosis

Question 24

Name the components of Virchow’s triad?

Answer 24

Question 25

What are 3 categories of the effects of ischaemia?

Answer 25

acute chronic acute-on-chronic

Question 26

What are the biochemical effects of ishaemia?

Answer 26

decrease oxygen --> anaerobic metabolism --> cell death

Question 27

Are all cells equally susceptible to ischemia?

Answer 27

no, different tissues have variable o2 requirement and are variably susceptible to ischemia

Question 28

What tissues are more affected ischaemia?

Answer 28

cells with high metabolic rate

Question 29

Name cells with a high metabolic rate

Answer 29

specialized cells... neurons heart muscles cells nerve cells

Question 30

What are the clinical effects of ischaemia?

Answer 30

dysfunction pain physical damage - specialized cells

Question 31

In the heart what can little bits of ischemia cause?

Answer 31

arrhythmia

Question 32

What would you call myocardial pain?

Answer 32

angina

Question 33

What are the outcomes of ischaemia?

Answer 33

no clinal effect resolution versus therapeutic intervention infarction

Question 34

What is the aetiology of infarction?

Answer 34

cessation of blood flow

Question 35

Name 4 things that can cause infarction? (cessation of blood flow)

Answer 35

thrombosis embolism strangulation e.g. gut trauma - cut/ ruptured vessel

Question 36

What are 4 factors which dictate the scale of damage of ischemia?

Answer 36

time period tissue organ pattern of blood supply previous disease

Question 37

How does anaerobic metabolism cause necrosis?

Answer 37

causes cell death --> liberation of enzymes --> breakdown of tissues (necrosis)

Question 38

Where would you get coagulation necrosis?

Answer 38

lung heart

Question 39

Where would you get colliquitive necrosis?

Answer 39

brain

Question 40

How long does it take to get myocyte necrosis?

Answer 40

20-40 minutes