ischameia and infarction

Question 1

what is 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 are the 4 types of hypoxia

Answer 2

hypoxic
anaemic
stagnant
cytotoxic

Question 3

what is ischemic heart disease

Answer 3

when the supply/demand of body tissues don’t match

CVD and high energy dmand like stress

Question 4

what happens if the radius reduces from 4 to 2`

Answer 4

there will be a 16 fold decrease in blood flow

Question 5

what cells are supceptible to ischaemia

Answer 5

cells with high metabolic rate are at greater risk

Question 6

what are the clinical effects of ischaemia

Answer 6

dysfunction

pain

physical damage

Question 7

what are the outcomes of ischaemia

Answer 7

no clinical effect

resolution by therapeutic intervention

infarction

Question 8

what is the aetiology (cause) of infarction

Answer 8

cessation of blood flow

Question 9

what causes cessation of blood flow

Answer 9

thrombosis
embolism
strangulation (gut arteries twisted)
trauma - cut or ruptured vessel

Question 10

what is the definition of infarction

Answer 10

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

Question 11

what factors effect the scale of damage caused by infarction

Answer 11

time period
tissue/organ (metabolic rate)
pattern of blood supply
previous disease

Question 12

what is the break down of tissue and cell death in the heart and lungs called

Answer 12

coagulative necrois

break down of the proteins

Question 13

what is the break down of tissue and cell death in the brain called

Answer 13

colliquative necrosis

fat break down

Question 14

what is the end result of infarcts

Answer 14

scar replaces area of tissue damage

possible reperfusion injury

Question 15

what is hypoxic hypoxia

Answer 15

low inspired O2

normal inspired O2 but low PaO2

Question 16

what is anaemic hypoxia

Answer 16

normal inspired O2 but blood abnormal

Question 17

what is stagnant Hypoxia

Answer 17

normal inspired O2 but abnormal delivery

ie local (occlusion of vessel)

systemic (shock)

Question 18

what is cytotoxic Hypoxia

Answer 18

normal inspired O2 but abnormal tissue level

Question 19

what factors affect oxygen supply

Answer 19

inspired O2
pulmonary function 
blood constituents
blood flow 
integrity of vasculature
tissue mechanisms

Question 20

what causes unstable angina

Answer 20

complicated atheroma

Question 21

what cuases stable angina

Answer 21

established atheroma

Question 22

atheroma in the aorta leads to

Answer 22

aneurysm

Question 23

what is the definition of infarction

Answer 23

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

Question 24

what determines the scale of damage from infarction

Answer 24

time period
tissue/organ
pattern of blood supply
previous disease

Question 25

when does heart failure start after infarction

Answer 25

2 minutes

when there is the loss of myocardial contractility

Question 26

when does irreversible damage occur relating to ischemia

Answer 26

sever ischemia - 20-30mins

Question 27

what happens 4-12 hours after a MI

Answer 27

Early coagulation necrosis, oedema, haemorrhage

Question 28

what happens 12-24 hours after a MI

Answer 28

Ongoing coagulation necrosis, myocyte changes, early neutrophilic infiltrate

Question 29

what happens 1-3 days after a MI

Answer 29

coagulation necrosis

loss of nucleis striations

Question 30

what happens 3-7 days after a MI

Answer 30

disintegration of dead myofibres, dying neutrophils, early phagocytosis

Question 31

what is a transmural infarction

Answer 31

ischaemic necrosis affects full thickness of the myocardium

Question 32

what is Subendocardial infarction

Answer 32

ischemic myocardium under the endocardial lining of the heart