Thrombosis and Embolism Flashcards
what is thrombosis?
- formation of a mass of blood within vasculature
- the solid mass is a thrombus
(clot = mass of blood outside vasculature)
how is a thrombus formed?
Vichows triad:
1. abnormalities in vessel wall
2. abnormalities in blood flow
3. abnormalities in blood components
what can cause abnormalities to form in vessel walls?
- atheroma
- inflammation
- direct injury
- damage to heart
what can cause abnormalities to form in blood flow?
- 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
what can cause abnormalities to different blood components?
hypercoagulative state:
* smokers
* pregnanacy and post partum
* post op patients
* trauma and burns
how do arterial thrombus appear?
- pale
- granular
- lower cell content (mostly fibrin)
- lines of Zahn (layers of platelets - fibrin - red blood cells)
how do venous thrombus appear?
- soft
- gelatinous
- redder (since more red blood cells)
- higher cell content
what are the different outcomes or complications of a thrombus?
- lysis
- propogate
- organise
- recanalise
- embolise
what is lysis?
- thrombus break down
- usually only occurs when thrombi are small
- blood flow is re-established
what is propagation?
thrombus is getting larger
(retrograde in arteries)
(anterograde in veins)
what is orgnaniation?
- repair process
- ingrowth of fibroblasts and capillaries
- lumen remains blocked
what is recanalisation?
one or more channels form through an area of organising thrombus
blood flow is usually re-established but not completely
what is an embolism?
- part of thrombus breaks off
- travels in blood stream
- lodges at a distant site
what are the effects of venous thrombosis on tissue?
congestion
oedema
ischaemia
infarction
what are the effects of arterial thrombosis on tissue?
ischaemia
infarction
(depends on site and collateral circulation)
what are some risk factors for DVT?
- immbolity
- post op
- pregancy and post partum
- long haul flight
what are complications of a pulmonary thromboembolism?
- 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
what are the different types of emboli?
- air - occur as a result of trauma
- amniotic fluid - occur during labour
- nitrogen
- medical equipment
- tumour cells
- fat or bone marrow
how can you prevent thrombosis and thromboembolisms?
- identify high risk patients
- leg compression during surgery
- TED stockings
- use heparin sub-cutaneously
- mobilise early, limit bed rest
what is the Well’s score?
determines how likely a patient is to have DVT
how can you treat thrombi and thromboemboli?
clot busting drugs: carry out thrombolysis
* streptokinase, ateplase
low molecular weight heparin
direct oral anticoagulants (DOAC): anti facor Xa
* rivaroxaban
* apixaban
