ischameia and infarction Flashcards
what is ischaemia
Relative lack of blood supply to tissue/organ leading to inadequate O2 supply to meet needs of tissue/organ: hypoxia
what are the 4 types of hypoxia
hypoxic
anaemic
stagnant
cytotoxic
what is ischemic heart disease
when the supply/demand of body tissues don’t match
CVD and high energy dmand like stress
what happens if the radius reduces from 4 to 2`
there will be a 16 fold decrease in blood flow
what cells are supceptible to ischaemia
cells with high metabolic rate are at greater risk
what are the clinical effects of ischaemia
dysfunction
pain
physical damage
what are the outcomes of ischaemia
no clinical effect
resolution by therapeutic intervention
infarction
what is the aetiology (cause) of infarction
cessation of blood flow
what causes cessation of blood flow
thrombosis
embolism
strangulation (gut arteries twisted)
trauma - cut or ruptured vessel
what is the definition of infarction
Ischaemic necrosis within a tissue/organ in living body produced by occlusion of either the arterial supply or venous drainage
what factors effect the scale of damage caused by infarction
time period
tissue/organ (metabolic rate)
pattern of blood supply
previous disease
what is the break down of tissue and cell death in the heart and lungs called
coagulative necrois
break down of the proteins
what is the break down of tissue and cell death in the brain called
colliquative necrosis
fat break down
what is the end result of infarcts
scar replaces area of tissue damage
possible reperfusion injury
what is hypoxic hypoxia
low inspired O2
normal inspired O2 but low PaO2
what is anaemic hypoxia
normal inspired O2 but blood abnormal
what is stagnant Hypoxia
normal inspired O2 but abnormal delivery
ie local (occlusion of vessel)
systemic (shock)
what is cytotoxic Hypoxia
normal inspired O2 but abnormal tissue level
what factors affect oxygen supply
inspired O2 pulmonary function blood constituents blood flow integrity of vasculature tissue mechanisms
what causes unstable angina
complicated atheroma
what cuases stable angina
established atheroma
atheroma in the aorta leads to
aneurysm
what is the definition of infarction
Ischaemic necrosis within a tissue/organ in living body produced by occlusion of either the arterial supply or venous drainage
what determines the scale of damage from infarction
time period
tissue/organ
pattern of blood supply
previous disease
when does heart failure start after infarction
2 minutes
when there is the loss of myocardial contractility
when does irreversible damage occur relating to ischemia
sever ischemia - 20-30mins
what happens 4-12 hours after a MI
Early coagulation necrosis, oedema, haemorrhage
what happens 12-24 hours after a MI
Ongoing coagulation necrosis, myocyte changes, early neutrophilic infiltrate
what happens 1-3 days after a MI
coagulation necrosis
loss of nucleis striations
what happens 3-7 days after a MI
disintegration of dead myofibres, dying neutrophils, early phagocytosis
what is a transmural infarction
ischaemic necrosis affects full thickness of the myocardium
what is Subendocardial infarction
ischemic myocardium under the endocardial lining of the heart
