Embolism, infarction, shock

What are the three common circulatory disorders?

Embolism Infarction Shock

What is an embolus?

A mass in blood vessels that can lodge and block a vessel lumen

What is the most common type of embolism?

Pulmonary embolism from deep leg vein thrombosis

What is thromboembolism?

An embolus formed from a dislodged thrombus

What determines the outcome of an embolism?

Origin of embolus and site where it lodges

Name common sources of emboli

Thrombus fragments infected lesions gas fat bone marrow tumour cells amniotic fluid

What type of gas emboli can occur in divers?

Nitrogen bubbles from rapid pressure change

What causes fat embolism?

Release of fat or bone marrow after fractures

Where do most pulmonary emboli originate?

Deep veins of the legs

Are most pulmonary emboli clinically obvious?

No most are small and silent

What severe outcomes can pulmonary embolism cause?

Sudden death right heart failure cardiovascular collapse

What happens if a pulmonary embolus blocks a medium vessel?

Pulmonary haemorrhage

What can repeated pulmonary emboli lead to?

Pulmonary hypertension

Where do most systemic arterial emboli originate?

Intracardiac mural thrombi

What percentage of systemic emboli are from unknown origin?

About 10 to 15 percent

What is the main consequence of arterial emboli?

Tissue infarction

What is an infarct?

An area of ischaemic necrosis due to blocked blood supply or drainage

What is infarction?

Death of tissue due to ischaemia from vascular occlusion

What is the main cause of infarcts?

Thrombotic or embolic arterial occlusion

Name other causes of infarction

Vasospasm haemorrhage in plaque vessel compression trauma

What is not considered infarction?

Necrosis caused by toxins or trauma

What determines the shape of an infarct?

Territory of the occluded blood supply

What shape are lung infarcts?

Wedge shaped

What shape are kidney infarcts?

Triangular

What shape are spleen infarcts?

Scarred

What is a white infarct?

An infarct with little haemorrhage in solid organs

Where do white infarcts occur?

Heart spleen kidney

What is a red infarct?

An infarct with significant haemorrhage

What is a septic infarct?

An infected infarct

What is a bland infarct?

An uninfected infarct

What factors influence infarct outcome?

Blood supply collateral circulation rate of occlusion tissue vulnerability oxygen content

Why is slow occlusion less damaging?

Allows time for collateral circulation to develop

Which cells are most vulnerable to hypoxia?

Neurons and myocardial cells

Can myocardial infarction be seen at 2 hours?

No changes are too early to detect

When is leukocyte infiltration most prominent after myocardial infarction?

2 to 4 days

What is shock?

A state of inadequate tissue perfusion

What causes hypotension in shock?

Reduced cardiac output or reduced circulating volume

What is cardiogenic shock?

Shock due to heart failure reducing cardiac output

What is hypovolaemic shock?

Shock due to loss of blood or plasma volume

What is septic shock?

Shock caused by infection leading to vasodilation and blood pooling

What is an embolus that is moving in blood called?

An embolism

How much blood does a healthy 70kg adult male have?

About 5 litres