Thrombosis Flashcards
two types of thombotic events
arterial
- coronary, cerebral, peripheral
venous
- DVT/PE
Differences between arterial + venous systems
arterial
- much thicker, have to withstand higher pressures
venous
- thinner, lower pressure, have valves
what causes an arterial thrombosis
atherosclerosis
how is an arterial thrombosis formed
damage to the epithelium – platelets adhesion + aggregation – coagulation – may completely occlude the vessel or can embolise
platelet rich thrombus
treatment of arterial thrombus
aspirin / clopidogrel
modify risk factors for atherosclerosis
what is activated in a venous thrombosis
coagulation cascade i.e. fibrin clot
platelets not activated
what dysfunction leads to venous thrombosis
dysfunction in VIRCHOW’S TRIAD
- stasis
- vessel wall damage
- hypercoagulability
treatment of venous thrombosis
heparin/warfarin/ other new oral anticoagulants
which type of thrombus is platelet rich
arterial
which type of thrombus is fibrin rich
venous
signs of DVT
limb feels HOT, SWOLLEN, TENDER
pitting oedema
signs of PE
pleuritic chest pain
hypoxia
cardiovascular collapse
right heart strain
risk factors for venous thromboembolism
Age obesity pregnancy previous DVT/PE trauma/surgery oestrogen therapy thrombophilia paralysis
why is pregnancy a risk factor for venous thromboembolism
clotting factors raise to about 3 times normal level to prepare for child birth
why does hypercoagulability increase risk of venous thromboembolism
all associated with the release of tissue factor, raised VWF and factor 8
what is thrombophilia
familial or acquired disorders of the haemostatic mechanism which are likely to predispose to thrombosis
mechanism for thrombophilia
decreased anti-coagulant activity
potential reasons for decreased anti-coagulant activity in thrombophilia
low levels of antithrombin III
low levels of protein C and S
role of protein C and S
switch off factor V, VIII, X
most common cause for decreased anti-coagulant activity
Factor V leiden
- varient in factor V gene- makes it more difficult for protein C and S to switch off factor V
what are hereditary thrombophilias
group of genetic defects in which affected individuals have increased tendency to develop premature, unusual and recurrent thrombosis
examples of hereditary thrombophilias
factor V leiden prothrombin 20210 mutation anti-thrombin deficiency protein C deficiency protein S deficiency
when should hereditary thrombophilia screening be considered
venous thrombosis <45 years old recurrent venous thrombosis unusual venous thrombosis family history of venous thrombosis family history of thrombophilia
management of hereditary thrombophilia
advice on avoiding risk
short term prophylaxis
- to prevent thrombic events during periods of known risk e.g. long haul flight
short term anticoagulation
- to treat thrombotic events
long term anticoagulation
- if recurrent thrombotic events
