thrombosis and embolism Flashcards
what is thrombosis
formation of a solid mass of blood within the circulatory system
the solid mass is called a thrombus
what’s the difference between a thrombus and a clot
a thrombus is within the circulatory system and a clot is outside the vessel wall.
when does a thrombus form
Virchow's triad abnormality in : 1. vessel wall 2. blood flow 3. blood components
what can cause damage to wall of the vascular system
atheroma - fatty deposition, calcification and narrowing of vessel inflammation inflammation direct injury damage to the <3
what problems can you have with blood flow
stasis- slowing of blood. narrowing, immobility , low blood pressure
turbulent blood flow- defects in wall and heart valves , atrial fibrillation , area of dead cardiac muscle.
name some hypercoagulable states
smokers - activates factor 12 pregnancy and post partum trauma & burns camper patients covid patients genetic/inherited disease
how does an arterial thrombus look
pale
granular
lower cell content
lines of Zahn (layering up of RBCs , platelets , fibrin)
how does a venous thrombus look
soft
gelatinous
deep red
higher cell content
explain thrombosis
platelet adhere to von Willebrand factor due to endothelial damage which releases factors to recruit more platelets.
intrinsic pathway of factor 2,8,9,10 and 11
extrinsic pathway of factor 5,7,10
both activate factor 10
prothrombin becomes thrombin
fibrinogen becomes fibrin
forms platelet plug.
explain the outcome/complications of thrombosis
lysis-breakdown of thrombus. blood flow re-established.
propagation-progressive spread of thrombosis.
organisation -reparative process. ingrowth of fibroblasts and capillaries. lumen remains obstructed.
recanalise- one or more channels form through areas of organising thrombus and blood flow can be re-established but usually incompletely.
embolise- part of thrombus breaks off and travels through blood stream and lodges at distant site.
effects of venous thrombosis on the tissue
congestion
oedema
ischaemia
infarction
effects of arterial thrombosis on the tissue
ischaemia
infarction
depends on site and collateral circulation.
what is embolism
blockage of a blood vessel by a solid, liquid or gas at a site distant from its origin.
pre-disposing factors for a DVT
immobility/bed rest post-operative pregnancy/post-partum oral contraceptives severe burns cardiac failure disseminated cancer superficial thrombophlebitis - inflammation of superficial veins of the legs.
how does a DVT look
oedema
unilateral swelling
indurated (hardened) appearance of surface of skin.
what can DVT lead to
pulmonary embolism
what happens if theres a massive coiled embolus in main pulmonary artery
sudden death
What happens if there is a small embolism lodged in peripheral pulmonary artery ?
pulmonary infarct
what happens if there is multiple repeated small emboli
pulmonary hypertension
name some embolisms
air in cannula/ syringe amniotic fluid nitrogen 'the bends' medical equipment tumour cells fat, BM
how to prevent thrombosis a thromboembolism
identify high risk patients Low Molecular Weight Heparin mobilise early and limit bed rest aspirin leg compressions during surgery- TED stockings , flowtron boots
when to suspect a DVT
well’s score of 2 or more.
D-dimers in blood (this is a fibrinogen degradation product)
anticoagulant therapy.
treatment for thrombos and thromboemboli
clot busters/ thrombolysis- streptokinase, ateplase
low molecular weight heparin.
anticoagulants- apixaban, rivaroxaban.
oral warfarin
mechanical intervention- filters on IVC, devices in left atria to stop thrombus fomation etc
embolectomy
