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)
What is a restriction of blood supply to a tissue called?
What is hypoxia?
Condition where part of the body is not recieving enough oxygen
What is the condition where part of the body is not recieving enough oxygen?
What are some different kinds of hypoxia?
What is hypoxic hypoxia?
Low inspired oxygen levels or normal inspired oxygen levels but low PaO2
What kind of hypoxia is low inspired oxygen levels or normal inspired oxygen levels but low PaO2?
What is anaemic hypoxia?
Normal inspired oxygen but blood is abnormal
What is the hypoxia with normal inspired oxygen levels but blood is abnormal?
What is stagnant hypoxia?
Normal inspired oxygen but abnormal delivery, due to local (occlusion of the vessel) or systemic problems (shock)
What is the hypoxia due to normal inspired oxygen but abnormal delivery, due to local (occlusion of the vessel) or systemic problems (shock)?
What is cytotoxic hypoxia?
Normal inspired oxygen but abnormal at tissue level
What hypoxia is due to normal inspired oxygen but abnormal at tissue level?
What are some factors that affect oxygen supply?
Integrity of vasculature
What are factors that affect oxygen demand?
Tissues itself (different tissues have different requirements)
Activity of the tissue above baseline value
What are the 2 general things that ischaemic heart tissue can be due to?
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)
Previous myocardial infarction
What is an example of a demand issue that can cause myocardial ischaemia?
Heart has high intrinsic demand, possible due to exertion or stress
What is atheroma/atherosclerosis?
Localised accumulation of lipid and fibrous tissue in intima of arteries
What is localised accumulation of lipid and fibrous tissue in intima of arteries called?
What are some of the clinical impacts of atheroma?
Ischaemia/infarction by thrombosis
Aneurysm (atheroma in the aorta)
What is stable angina?
Established atheroma in coronary arteries
What does an established atheroma in the coronary arteries cause?
What is unstable angina?
Complicated atheroma in the coronary arteries
What is a complicated atheroma in the coronary arteries called?
What are some possible clinical consequences due to atheroma?
Transient ischaemic attack (TIA)
Abdominal aortic aneurysm
Peripheral vascular disease
What does TIA stand for?
Transient ischaemic attack
What is a transient ischaemic attack?
Brief interruption of blood flow to part of the brain that causes temporary stroke like symptoms
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)
What is a brief interruption of blood flow to part of the brain that causes temporary stroke like symptoms called?
Transient ischaemic attack
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
What is an area of necrotic tissue in th ebrain resulting from a blockage or narrowing in the arteries supplying it with blood called?
What is an abdominal aortic aneursm?
Localised enlargement of the abdominal aorta so the diameter is greater than 3cm
What is localised enlargement of the abdominal aorta so the diameter is greater than 3cm called?
Abdominal aortic aneurysm
What is it called when the heart does not pump blood as well as it should?
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
What is cardiac failure?
Heart does not pump blood as well as it should
What does coronary artery disease lead to, and then what does this lead to?
Coronary artery disease -> myocardial infarction -> cardiac failure
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
What are the different categories of ischaemia?
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
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
What cannot be performed in a cell without oxygen?
What are the clinical effects of ischaemia?
What are the possible outcomes of ischaemia?
No clinical effect
Resolution verses therapeutic intervention
What is infarction?
Obstruction of the blood supply to an organ or region of tissue causing death of the tissue
What is infarction due to?
Cessation of blood flow
What is the aetiology of infarction?
What does the scale of damage due to ischaemia/infarction depend on?
Pattern of blood supply
What is the biochemical process of infarction?
1) Anaerobic respiration
2) Cell death
3) Liberation of enzymes
4) Breakdown of tissue
What are examples of infarction?
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
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?
What is colliquative necrosis?
Type of necrosis that results in transformation of the tissue into liquid viscous mass
What is the type of necrosis that results in transformation of the tissue into liquid viscous mass called?
Where does coagulative necrosis occur?
Heart and lungs
Where does colliquative necrosis occur?
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
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)
What are examples of microstructure changes that occurs due to myocardial infarction?
Cell and mitochrondrial swelling
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
How does the appearance of infarcts change between 24-48 hours?
Previously congested tissues
Second/continuing blood supply
Acute inflammation initially at edge of infarct, leading to loss of specialisd cell features
How does the appearance of infacts change after 72 hours?
Pale infarct (yellow/white and red periphery)
Red infarct (little change)
Macrophages remove debris
What are examples of pale infarcts?
What are examples of red infarcts?
What is the end appearance of infarction?
Scar replaces area of tissue damage
Shape depend on territory of occluded vessel
What is reperfusion?
Tissue damage caused when blood supply returns to a tissue after a period of ischaemia
What is tissue damage caused when blood supply returns to a tissue after a period of ischaemia called?
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
What is the microscopic process of myocardial infarction?
4 TO 12 HOURS
Early coagulation necrosis
12 TO 24 HOURS
Ongoing coagulation necrosis
Early neutrophilic infiltrate
1 TO 3 DAYS
Loss of nuclei and striations
Brisk neutrophilic infiltrate
3 TO 7 DAYS
Disintegration of dead myofibrils
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
MORE THAN 2 MONTHS
Dense collagenous scar
What are the 2 different kinds of myocardial infarction?
What is a transmural infarction?
Ischaemic necrosis affects full thickness of the myocardium
What is it called when ischaemic necrosis affects full thickness of the myocardium?
What is subendocardial infarction?
Ischaemic necrosis mostly limited to a zone of the myocardium under the endocardial lining of the heart
What is it called when ischaemic necrosis mostly limited to a zone of the myocardium under the endocardial lining of the heart?
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)
Clinically, what are acute infarcts classifed according to?
Whethere there is an elevation of the ST segment on the ECG:
Clinically, what are the 2 kinds of acute infarcts?
What does STEMI stand for?
ST elevated myocardial infarction
What does NSTEMI stand for?
Non-ST elevated myocardial infarction
What kind of myocardial infarction is NSTEMI thought to correlate with?
What does the effects of infarction depend on?
Site of infarct (within body and organ)
Size of infarct
Contribution of previous disease/infarction
What are some possible effects of infarction?
What can complications of myocardial infarction be classified as?
What are some examples of complications of myocardial infarctions?
Cardiac rupture (ventricular wall, septum or papillary muscle
Pulmonayr embolism secondary to deep vein thrombosis