19. Thrombosis and Embolism

Question 1

What are the components of a thrombus?

Answer 1

Platelets
Fibrin
RBCs

Question 2

What factors do endothelial cells normally produce?

Answer 2

Prostacyclin
Thrombomodulin
Plasminogen activator
NO

Question 3

What is the function of prostacyclin?

Answer 3

Platelet inhibitor

Question 4

What factors do endothelial cells produced when damaged?

Answer 4

Platelet Aggregating Factor

Plasminogen Activator Inhibitors

Question 5

What factor do platelets release when they aggregate?

Answer 5

Thromboxane

Question 6

What factors can cause endothelial damage?

Answer 6

Plaque in atherosclerosis
Vasculitis
Hypertension
Turbulent flow
Cigarette smoke

Question 7

Why can abnormal flow predispose to thrombosis?

Answer 7

Platelets in contact with endothelium
Clotting factors aren’t diluted by flowing blood
Slows clotting inhibitors getting to the site
Allows build up of thrombi
Promotes endothelial cell activation

Question 8

What is the most common form of abnormal flow in arteries?

Answer 8

Turbulence

Question 9

What is the most common form of abnormal flow in veins?

Answer 9

Stasis

Question 10

What factors can cause venous stasis?

Answer 10

Immobility
heart failure
Shock
External pressure
Aneurysms

Question 11

Give 2 causes of primary hypercoaguability

Answer 11

Mutation in factor V gene

Prothrombin gene

Question 12

Give 2 reasons of secondary hypercoaguability

Answer 12

Cancer

DIC

Question 13

What are the consequences of thrombi in an artery?

Answer 13

Ischaemia, infarction and emboli

Question 14

What consequence can a thrombus have in veins?

Answer 14

PE

Question 15

What are the possible fates of a thrombus?

Answer 15

Propagation (leading to vessel obstruction)
Embolisation
Dissolution
Scarring and recanalisation of blood vessel

Question 16

What are the consequences of thrombi in capillaries?

Answer 16

Frost bite

Necrosis and ulceration

Question 17

How does COVID-19 cause vasoconstriction and thrombosis?

Answer 17

Uses ACE-2 enzyme to get into the cell, which inactivates the enzyme
High ACE and angiotensin 2 cause vasoconstriction and thrombosis

Question 18

What things can cause thrombi to form in the heart?

Answer 18

Post MI
Valves in infective endocarditis
LA in atrial fibrillation

Question 19

What effect does a massive pulmonary embolus have?

Answer 19

Wedges in pulmonary artery and causes sudden death

Question 20

What effect does an intermediate pulmonary embolus have?

Answer 20

May cause infarction

Necrosis will only happen if circulation is already compromised as lungs have dual circulation

Question 21

What effect can pulmonary microemboli have?

Answer 21

Block small pulmonary arterioles

Cause right heart failure

Question 22

Where are the most common places for systemic emboli to arise?

Answer 22

Left heart
Aorta
Carotids

Question 23

How are air emboli created?

Answer 23

If the veins of head or neck are cut, air is sucked in during inspiration

Question 24

What effect can an air embolus have?

Answer 24

Reduces heart pump function as when ventricles contract they only serve to compress air

Question 25

What causes decompression sickness?

Answer 25

High pressure (eg. divers) cause an increase of nitrogen in body fluids
Rapidly decreasing pressure cause nitrogen bubbles to form

Question 26

What is the bends?

Answer 26

Bubbles form in muscles and joints

Question 27

What is the chokes?

Answer 27

Oedema and haemorrhage in lungs

Ischaemia

Question 28

How are fat emboli created?

Answer 28

Fracture of long bones

Question 29

What are the symptoms of a fat embolus?

Answer 29

Dyspnoea and cyanosis
CNS symptoms
Petechial haemorrhages