Thrombosis and Embolism

Question 1

what is thrombosis?

Answer 1

• formation of a mass of blood within vasculature
• the solid mass is a thrombus
  (clot = mass of blood outside vasculature)

Question 2

how is a thrombus formed?

Answer 2

Vichows triad:
1. abnormalities in vessel wall
2. abnormalities in blood flow
3. abnormalities in blood components

Question 3

what can cause abnormalities to form in vessel walls?

Answer 3

• atheroma
• inflammation
• direct injury
• damage to heart

Question 4

what can cause abnormalities to form in blood flow?

Answer 4

• stasis (slowing of blood) - due to narrowing of lumen, immobility or low BP
• Turbulent blood flow - due to defects in vessel wall and heart valves, atrial fibrilation or ischaemia

Question 5

what can cause abnormalities to different blood components?

Answer 5

hypercoagulative state:
* smokers
* pregnanacy and post partum
* post op patients
* trauma and burns

Question 6

how do arterial thrombus appear?

Answer 6

• pale
• granular
• lower cell content (mostly fibrin)
• lines of Zahn (layers of platelets - fibrin - red blood cells)

Question 7

how do venous thrombus appear?

Answer 7

• soft
• gelatinous
• redder (since more red blood cells)
• higher cell content

Question 8

what are the different outcomes or complications of a thrombus?

Answer 8

• lysis
• propogate
• organise
• recanalise
• embolise

Question 9

what is lysis?

Answer 9

• thrombus break down
• usually only occurs when thrombi are small
• blood flow is re-established

Question 10

what is propagation?

Answer 10

thrombus is getting larger
(retrograde in arteries)
(anterograde in veins)

Question 11

what is orgnaniation?

Answer 11

• repair process
• ingrowth of fibroblasts and capillaries
• lumen remains blocked

Question 12

what is recanalisation?

Answer 12

one or more channels form through an area of organising thrombus
blood flow is usually re-established but not completely

Question 13

what is an embolism?

Answer 13

• part of thrombus breaks off
• travels in blood stream
• lodges at a distant site

Question 14

what are the effects of venous thrombosis on tissue?

Answer 14

congestion
oedema
ischaemia
infarction

Question 15

what are the effects of arterial thrombosis on tissue?

Answer 15

ischaemia
infarction
(depends on site and collateral circulation)

Question 16

what are some risk factors for DVT?

Answer 16

• immbolity
• post op
• pregancy and post partum
• long haul flight

Question 17

what are complications of a pulmonary thromboembolism?

Answer 17

• if there is a large embolism of main pulmonary artery it causes sudden death
• if there is a smaller embolism of peripheral pulmonary artery it causes pulmonary infarction
• if there are multiple smaller emboli it causes pulmonary hypertension

Question 18

what are the different types of emboli?

Answer 18

• air - occur as a result of trauma
• amniotic fluid - occur during labour
• nitrogen
• medical equipment
• tumour cells
• fat or bone marrow

Question 19

how can you prevent thrombosis and thromboembolisms?

Answer 19

• identify high risk patients
• leg compression during surgery
• TED stockings
• use heparin sub-cutaneously
• mobilise early, limit bed rest

Question 20

what is the Well’s score?

Answer 20

determines how likely a patient is to have DVT

Question 21

how can you treat thrombi and thromboemboli?

Answer 21

clot busting drugs: carry out thrombolysis
* streptokinase, ateplase

low molecular weight heparin

direct oral anticoagulants (DOAC): anti facor Xa
* rivaroxaban
* apixaban