Pathophysiology of Ischaemia & Infarction Flashcards Preview

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Flashcards in Pathophysiology of Ischaemia & Infarction Deck (85):
1

What is ischaemia?

Restriction in the blood supply to tissues, causing a shortage of oxygen that is needed for cellular respiration (to keep the tissue alive)

2

What is a restriction of blood supply to a tissue called?

Ischaemia

3

What is hypoxia?

Condition where part of the body is not recieving enough oxygen

4

What is the condition where part of the body is not recieving enough oxygen?

Hypoxia

5

What are some different kinds of hypoxia?

Hypoxic

Anaemic

Stagnant

Cytotoxic

6

What is hypoxic hypoxia?

Low inspired oxygen levels or normal inspired oxygen levels but low PaO2

7

What kind of hypoxia is low inspired oxygen levels or normal inspired oxygen levels but low PaO2​?

Hypoxic

8

What is anaemic hypoxia?

Normal inspired oxygen but blood is abnormal

9

What is the hypoxia with normal inspired oxygen levels but blood is abnormal?

Anaemia

10

What is stagnant hypoxia?

Normal inspired oxygen but abnormal delivery, due to local (occlusion of the vessel) or systemic problems (shock)

11

What is the hypoxia due to normal inspired oxygen but abnormal delivery, due to local (occlusion of the vessel) or systemic problems (shock)?

Stagnant hypoxia

12

What is cytotoxic hypoxia?

Normal inspired oxygen but abnormal at tissue level

13

What hypoxia is due to normal inspired oxygen but abnormal at tissue level?

Cytotoxic hypoxia

14

What are some factors that affect oxygen supply?

Inspired oxygen

Pulmonary function

Blood constituents

Blood flow

Integrity of vasculature

Tissue mechanisms

15

What are factors that affect oxygen demand?

Tissues itself (different tissues have different requirements)

Activity of the tissue above baseline value

16

What are the 2 general things that ischaemic heart tissue can be due to?

Supply issues

Demand issues

17

What are some examples of supply issues that can cause ischaemic heart disease?

Coronary artery atheroma

Cardiac failure (flow)

Pulmonary function (other disease or pulmonary oedema)

Anaemia

Previous myocardial infarction

18

What is an example of a demand issue that can cause myocardial ischaemia?

Heart has high intrinsic demand, possible due to exertion or stress

19

What is atheroma/atherosclerosis?

Localised accumulation of lipid and fibrous tissue in intima of arteries

20

What is localised accumulation of lipid and fibrous tissue in intima of arteries called?

Atheroma/atherosclerosis

21

What are some of the clinical impacts of atheroma?

Stable angina

Unstable angina

Ischaemia/infarction by thrombosis

Aneurysm (atheroma in the aorta)

22

What is stable angina?

Established atheroma in coronary arteries

23

What does an established atheroma in the coronary arteries cause?

Stable angina

24

What is unstable angina?

Complicated atheroma in the coronary arteries

25

What is a complicated atheroma in the coronary arteries called?

Unstable angina

26

What are some possible clinical consequences due to atheroma?

Myocardial infarction

Transient ischaemic attack (TIA)

Cerebral infarction

Abdominal aortic aneurysm

Peripheral vascular disease

Cardiac failure

27

What does TIA stand for?

Transient ischaemic attack

28

What is a transient ischaemic attack?

Brief interruption of blood flow to part of the brain that causes temporary stroke like symptoms

29

What is peripheral vascular disease?

Blood circulation disorder that causes the blood vessels outisde of your art and brain to narrow, block or spasm (happens in arteries or veins)

30

What is a brief interruption of blood flow to part of the brain that causes temporary stroke like symptoms called?

Transient ischaemic attack

31

What is a cerebral infarction?

Area of necrotic tissue in th ebrain resulting from a blockage or narrowing in the arteries supplying it with blood

32

What is an area of necrotic tissue in th ebrain resulting from a blockage or narrowing in the arteries supplying it with blood called?

Cerebral infarction

33

What is an abdominal aortic aneursm?

Localised enlargement of the abdominal aorta so the diameter is greater than 3cm

34

What is localised enlargement of the abdominal aorta so the diameter is greater than 3cm called?

Abdominal aortic aneurysm

35

What is it called when the heart does not pump blood as well as it should?

Heart failure

36

What is blood circulation disorder that causes the blood vessels outisde of your art and brain to narrow, block or spasm (happens in arteries or veins) called?

Peripheral vascular disease

37

What is cardiac failure?

Heart does not pump blood as well as it should

38

What does coronary artery disease lead to, and then what does this lead to?

Coronary artery disease -> myocardial infarction -> cardiac failure

39

In terms of formular, why does an atheroma have an impact on blood flow?

Atheroma decreases the radius of the vessel, causing decrease in flow (to the power of 4)

This decreases the delivery of oxygen and causes myocardial infarction

40

What are the different categories of ischaemia?

Acute

Chronic

Acute-on-chronic

41

How does ischaemia effect cells biochemically?

Decreased oxygen means aerobic respiration is not possible

So cell performs anaerobic respiration

Which does not produce enough energy

Cell death occurs

42

What can be said about the impact of ischaemia on different tissues?

Different tissues have variable oxygen demands and so have variable susceptibility to ischaemia

43

What cannot be performed in a cell without oxygen?

Aerobic respiration

44

What are the clinical effects of ischaemia?

Dysfunction

Pain

Physical damage

45

What are the possible outcomes of ischaemia?

No clinical effect

Resolution verses therapeutic intervention

Infarction

46

What is infarction?

Obstruction of the blood supply to an organ or region of tissue causing death of the tissue

47

What is infarction due to?

Cessation of blood flow

48

What is the aetiology of infarction?

Thrombosis

Embolism

Strangulation

Trauma

49

What does the scale of damage due to ischaemia/infarction depend on?

Time period

Tissue/organ

Pattern of blood supply

Previous disease

50

What is the biochemical process of infarction?

1) Anaerobic respiration

2) Cell death

3) Liberation of enzymes

4) Breakdown of tissue

51

What are examples of infarction?

Coagulative necrosis

Colliquative necrosis

52

What is coagulative necrosis?

Accidental cell death typically caused by ischaemia or infarction, architecture of dead tissue is preserved for a few days so if surrounded by healthy tissue regeneration can occur

53

What is accidental cell death typically caused by ischaemia or infarction, architecture of dead tissue is preserved for a few days so if surrounded by healthy tissue regeneration can occur called?

Coagulative necrosis

54

What is colliquative necrosis?

Type of necrosis that results in transformation of the tissue into liquid viscous mass

55

What is the type of necrosis that results in transformation of the tissue into liquid viscous mass called?

Colliquative necrosis

56

Where does coagulative necrosis occur?

Heart and lungs

57

Where does colliquative necrosis occur?

Brain

58

What is the process of myocardial infarction?

1) Coronary artery obstruction

2) Decrease in blood flow to region of the myocardium

3) Ischaemia and rapid myocardial dysfunction

4) Myocyte death

59

What does myocardial infarction lead to?

Anaerobic respiration, onset of ATP depletion (within seconds)

Loss of myocardial contractility which leads to heart failure (within 2 minutes)

Ultrastructural changes (after a few minutes)

Myocyte necrosis (20-40 minutes)

Injury to the microvasculature (after 1 hour)

60

What are examples of microstructure changes that occurs due to myocardial infarction?

Myofibrillar relaxation

Glycogen depletion

Cell and mitochrondrial swelling

61

How does the appearance of infarcts change within less than 24 hours?

No change on visual inspection

A few hours to 12 hours post insult see swollen mitochondria on electron microscopy

62

How does the appearance of infarcts change between 24-48 hours?

PALE INFARCT

Solid tissues

 

RED INFARCT

Loose tissues
Previously congested tissues
Second/continuing blood supply
Venous occlusion

 

MICROSCOPICALLY

Acute inflammation initially at edge of infarct, leading to loss of specialisd cell features

 

63

How does the appearance of infacts change after 72 hours?

MACROSCOPICALLY

Pale infarct (yellow/white and red periphery)
Red infarct (little change)

 

MICROSCOPICALLY

Chronic inflammation
Macrophages remove debris
Granulation tissue
Fibrosis

64

What are examples of pale infarcts?

Myocardium

Spleen

Kidney

65

What are examples of red infarcts?

Lung

Liver

66

What is the end appearance of infarction?

Scar replaces area of tissue damage

Shape depend on territory of occluded vessel

Possibly reperfusion

67

What is reperfusion?

Tissue damage caused when blood supply returns to a tissue after a period of ischaemia

68

What is tissue damage caused when blood supply returns to a tissue after a period of ischaemia called?

Reperfusion

69

What is the reparative process after infarction?

 

1) Cell death

2) Acute inflammation

3) Macrophages phagocytosis of dead cells

4) Granulation tissue

5) Collagen deposition (fibrosis)

6) Scar formation

70

What is the microscopic process of myocardial infarction?

4 TO 12 HOURS

Early coagulation necrosis
Oedema
Haemorrhage

 

12 TO 24 HOURS

Ongoing coagulation necrosis
Myocyte changes
Early neutrophilic infiltrate

 

1 TO 3 DAYS

Coagulation necrosis
Loss of nuclei and striations
Brisk neutrophilic infiltrate

 

3 TO 7 DAYS

Disintegration of dead myofibrils
Dying neutrophils
Early phagocytosis

 

7 TO 10 DAYS

Well developed phagocytosis
Granulation tissue at margins

 

10 TO 14 DAYS

Well established granulation tissue with new blood vessels and collagen deposition

 

2 TO 8 WEEKS

Increased collagen deposition
Decreased cellularity

 

MORE THAN 2 MONTHS

Dense collagenous scar

71

What are the 2 different kinds of myocardial infarction?

Transmural infarction

Subendocardial infarction

72

What is a transmural infarction?

Ischaemic necrosis affects full thickness of the myocardium

73

What is it called when ischaemic necrosis affects full thickness of the myocardium?

Transmural infarction

74

What is subendocardial infarction?

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

75

What is it called when ischaemic necrosis mostly limited to a zone of the myocardium under the endocardial lining of the heart?

Subendocardial infarction

76

How do the histological features compare between transmural and subendocardial infactions?

They are the same (same repair time and granulation tissue stage followed by fibrosis)

77

Clinically, what are acute infarcts classifed according to?

Whethere there is an elevation of the ST segment on the ECG:

NSTEMI
STEMI

78

Clinically, what are the 2 kinds of acute infarcts?

STEMI

NSTEMI

79

What does STEMI stand for?

ST elevated myocardial infarction

80

What does NSTEMI stand for?

Non-ST elevated myocardial infarction

81

What kind of myocardial infarction is NSTEMI thought to correlate with?

Subendocardial infarction

82

What does the effects of infarction depend on?

Site of infarct (within body and organ)

Size of infarct

Contribution of previous disease/infarction

83

What are some possible effects of infarction?

Death

Dysfunciton (pain)

84

What can complications of myocardial infarction be classified as?

Immediate

Early

Late

85

What are some examples of complications of myocardial infarctions?

Sudden death

Arrhythmias

Angina

Cardiac failure

Cardiac rupture (ventricular wall, septum or papillary muscle

Reinfarction

Pericarditis

Pulmonayr embolism secondary to deep vein thrombosis

Mitral incompetence

Ventricular aneurysm

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