Pathophysiology of Thrombosis and Embolism

Question 1

Give 3 factors affecting the vascular system

Answer 1

• pressure gradient
• resistance
• viscosity of blood
• velocity
• compliance

Question 2

Are muscular arteries more or less compliant than elastic arteries?

Answer 2

Less compliant

Question 3

What kind of flow is normal blood flow?

Answer 3

Laminar

Question 4

What is stasis?

Answer 4

Stagnation of blood flow

Question 5

Give 3 examples of when stasis might occur

Answer 5

• in cardiac failure
• post-operative
• post long-haul flights

Question 6

What is turbulent blood flow?

Answer 6

Forceful, unpredictable blood flow

Question 7

What kind of blood flow would be most likely to occur following the protrusion of an atheromatous plaque into the lumen of a blood vessel?

Answer 7

Turbulent

Question 8

What form of hypoxia might cause hyper-viscosity?

Answer 8

Chronic hypoxia

Question 9

What is vaculitis?

Answer 9

Inflammation of a blood vessel wall

Question 10

What is caused by vascular steal?

Answer 10

Retrograde blood flow through vertebral artery due to subclavian artery obstruction

Question 11

Other than thromboembolism, give 3 causes of defects in blood flow

Answer 11

• atheroma
• hyperviscosity
• spasm
• external compression
• vasculitis
• vascular steal

Question 12

What is Virchow’s triad?

Answer 12

Three broad categories of factors that cause thrombosis

Question 13

What is a thrombus?

Answer 13

A solid mass formed from constituents of blood within the vascular system during life

Question 14

What is the first step in the pathogenesis of thrombosis?

Answer 14

Endothelial injury

Question 15

What is the most important risk factor for developing thrombosis?

Answer 15

Hypercholesterolaemia

Question 16

What is caused by turbulent flow when there is already an atheromatous plaque present in the vessel?

Answer 16

More loss of surface so more area exposed for thrombus formation
Thrombus may break off and travel elsewhere

Question 17

What three features of the blood/blood vessels are changed in the pathogenesis of thrombosis?

Answer 17

• vessel wall
• blood constituents
• blood flow

Question 18

Give 3 factors on which the consequences of thrombosis depend

Answer 18

• site of thrombus
• extent of thrombus
• collateral circulation

Question 19

Give 3 common clinical scenarios resulting from thrombosis

Answer 19

• deep venous thrombosis
• limb ischaemia
• myocardial infarction

Question 20

What are the possible outcomes of thrombosis?

Answer 20

• Resolution (without medical intervention)
• Organisation/Recanalisation
• Death
• Propagation leading to embolism

Question 21

What is an embolus?

Answer 21

A detatched intravascular solid, liquid or gaseous mass

Question 22

Give 3 sources of systemic/arterial thromboembolus

Answer 22

• mural thrombus
• aortic aneurysms
• atheromatous plaque
• valvular vegetations

Question 23

A systemic thromboembolus usually causes infarction, however what 3 factors does this depend on?

Answer 23

• vulnerability of affected tissues to ischaemia
• calibre of occluded vessel
• collateral circulation

Question 24

What is the most common form of thromboembolic disease and from where does this originate?

Answer 24

Venous thromboembolus

Originates from deep venous thromboses

Question 25

Venous thromboemboli travel to what circulation?

Answer 25

Pulmonary arterial circulation

Question 26

Give four consequences of pulmonary thromboembolism

Answer 26

- pulmonary haemorrhage - pulmonary infarction - right heart failure - sudden death

Question 27

What would be caused by multiple pulmonary embolisms over time if the pulmonary emboli were small enough not to cause sudden death?

Answer 27

Pulmonary hypertension and right ventricular failure

Question 28

Give 5 risk factors for deep venous thrombosis and pulmonary thromboembolism

Answer 28

- cardiac failure - post-operative/post-partum patients - nephrotic syndrome - disseminated malignancy - oral contraceptive pill - increased risk with increased age - immobilisation - obesity - past medical history of DVT

Question 29

When would a fat embolus occur?

Answer 29

After major trauma/fractures

Question 30

What 3 organs are most commonly affected by fat embolus?

Answer 30

Brain, kidneys, skin

Question 31

When would a gas embolus commonly occur?

Answer 31

In decompression sickness in divers, nitrogen forms as bubbles which lodge in capillaries due to rapid decompression

Question 32

Where/when would an air embolus occur?

Answer 32

- head and neck wounds - surgery - central venous lines

Question 33

What is the major risk factor of tumour emboli?

Answer 33

Tumour emboli may be a method of metastasis, emboli break off and leave metastatic deposits elsewhere

Question 34

What kind of embolus can occur in pregnant women?

Answer 34

Trophoblast embolism

Question 35

Give a condition in which a septic material embolism might occur?

Answer 35

Infective endocarditis

Question 36

What would an amniotic fluid embolus in the circulation cause?

Answer 36

Collapse and/or death

Question 37

What kind of embolism might occur following a fracture?

Answer 37

Bone marrow embolism

Question 38

Give two causes of foreign body embolism

Answer 38

- intravascular cannula tips | - sutures