Ischaemia And Infarction

Question 1

Hypoxic hypoxia

Answer 1

Low inspired O2

Or normal inspired O2 but low PaO2

Question 2

Anaemic hypoxia

Answer 2

Normal inspired O2 but blood is abnormal

Question 3

Stangnant hypoxia

Answer 3

Normal inspired O2 but abnormal delivery from local occlusion of vessel or systemic effects eg shock

Question 4

Cytotoxic hypoxia

Answer 4

Normal inspired O2 but abnormal at tissue level

Question 5

Factors affecting oxygen supply

Answer 5

Inspired O2
Pulmonary function
Blood constituents
Blood flow
Integrity of vasculature
Tissue mechanisms

Question 6

Factors affecting oxygen demand

Answer 6

Different types of tissue

Activity of tissues above baseline value

Question 7

Causes of supply issues in is ischaemic heart disease

Answer 7

Coronary artery atheroma, cardiac failure, pulmonary disease or oedema (LVF), anaemia, previous MI

Question 8

Cause of demand issues in is ischaemic heart disease

Answer 8

Heart has high Intrinsic demand, exertion/stress

Question 9

Atheroma types in coronary artery

Answer 9

Established - stable angina(on exertion)

Complicated - unstable angina (at rest)

Ulcerated/fissured - thrombosis then ischaemia/infarction

Question 10

Clinical consequences of ischemia

Answer 10

MI
TIA
Cerebral infarction
Abdominal aortic aneurysm
Peripheral vascular disease
CF

Question 11

blood flow formula

Answer 11

Q= difference in Pressure over resistance

Resistance is worked out with radius and constants and length and viscosity

Question 12

Biochemical effects of ischemia

Answer 12

Only anaerobic respiration so less ATP

Lactate produces and the acid damages tissue

Question 13

Clinical effects/symptoms of ischemia

Answer 13

Dysfunction
Pain
Physical damage

Question 14

Outcomes of ischemia

Answer 14

No clinical effects
Resolution with or without therapeutic intervention
Infarction

Question 15

Causes of infarction

Answer 15

Thrombosis
Embolism
Strangulation eg gut
trauma

Occlusion of either arterial supply or venous drainage

Question 16

what is coagulative necrosis and where does it happen

Answer 16

Goes hard eg heart, lung

Question 17

Colliquitive necrosis

Answer 17

Eg brain, draws fluid

Question 18

Onset time of anaerobic metabolism and ATP depletion in MI

Answer 18

Seconds

Question 19

Onset of loss of myocardial contractility (heart failure) in MI

Answer 19

Less than 2 minutes

Question 19

Onset of loss of myocardial contractility (heart failure) in MI

Answer 19

Less than 2 minutes

Question 20

Onset of ultrastructural changes in MI eg myofibrillar relaxation, glycogen depletion, cell and mitochondrial swelling

Answer 20

A few minutes

Question 21

When does severe ischaemia become irreversible in MI

Answer 21

20-30 minutes

Question 22

Onset of myocyte necrosis (disruption of sarcolemmal membrane and leakage of cell contents) in MI

Answer 22

20-40 minutes

Question 23

Onset of injury to microvasculature in MI

Answer 23

Over an hour

Question 24

Changes of appearance of infarcts at under 24 hours

Answer 24

No visual but under EM swollen mitochondria at under 12 hours

Question 25

Changes of appearance of infarcts at 24-48 hours

Answer 25

Pale infarct eg myocardium, spleen , kidney (solid tissues) Or Red infarct eg lung, liver (loose tissues, previously congested tissue, second/continuing blood supply, venous occlusion Microscopically, acute inflammation initially at edges, loss of specialised cell features

Question 26

Changes in appearance of infarcts at 72hours

Answer 26

Pale infarct with red periphery Red little change Chronic inflammation, MQ to remove debris, granulation tissue, fibrosis

Question 27

End result appearance of infarcts

Answer 27

Scar replaces tissue damage

Question 28

Reparative processes in myocardial infarction

Answer 28

``` Cell death Acute inflammation Macrophages phagocytosing dead cells Granulation tissue Collagen deposition (fibrosis) Scar formation ```

Question 29

4-12 hours of myocardial infarction

Answer 29

Early coagulation necrosis, odema and haemorrhage

Question 30

12-24 hours of myocardial infarction

Answer 30

Ongoing coagulation necrosis, myocyte changes, early neutrophilic infiltrate

Question 31

1-3 days of myocardial infarction

Answer 31

Coagulation necrosis again, loss of nuclei and striations, brisk neutrophilic infiltrate

Question 32

3-7 days of myocardial infarction

Answer 32

Disintegration of dead myofibres, dying neutrophils, early phagocytosis

Question 33

7-10 days of myocardial infarction

Answer 33

Well developed phagocytosis, granulation tissue at margins

Question 34

10-14 days of myocardial infarction

Answer 34

Well established granulation tissue with new blood vessels and collagen deposition

Question 35

2-8 weeks of myocardial infarction

Answer 35

Increased collagen deposition, decreased cellularity

Question 36

>2 months of myocardial infarction

Answer 36

Dense collagenous scar

Question 37

Transmural infarction

Answer 37

Ischemic necrosis affects full thickness of myocardium

Question 38

Subendocardial infarction

Answer 38

Ischemic necrosis mostly limited to a zone of myocardium under the endocardial lining of the heart

Question 39

What type of infarct correlates with Non-stemi

Answer 39

Subendocardial