Venous Thrombosis Flashcards
what are common arterial thrombotic events
coronary- MI
cerebral- CVA
peripheral- pain, gangrene, loss of limb
what are common venous thrombotic events
DVT- lower limb most common
PE
what side of heart to DVTs go to when dislodged and cause a PE
right side
what moves blood in leg veins back to hearts
leg muscles and valves
what causes arterial thrombosis
athersclerosis- cholesterol plaque builds up
high pressure system causes plaque to rupture damaging vessel
this exposes collagen and causes platelet binding
platelet rich thrombus blocks vessel
what type of thombus is arterial
platelet rich
what is the treatment for arterial thrombosis
aspirin / other antiplatelet
modify risk factors for athersclerosis
what causes a venous thrombosis
low pressure system
virchows triad:
-stasis of blood: congeals
activates coagulation cascade- fibrin rich clot
- vessel wall: deterioration of valves (age, previous VTE)
- hypercoagulability (elevated tissue factor/ CF or low levels of antithrombin / proteins C and S)
what type of clot in venous thrombosis
fibrin rich
what type of drug for venous thrombosis
heparin/warfarin/ NOAC as secondary haemostasis
what is the biggest risk factor for VTE
previous VTE
what are the features of a DVT
limb feels hot, swollen and tender
pitting oedema
what are the differentials for a DVT
cardiac failure (would affect both legs)
infection
cellulitis
what are the consequences of PE
(pulmonary embolism causing infarction) pleuritic chest pain (lodges peripherally, inflamed lung rubs on chest wall) cardiovascular collaspe/ death hypoxia right side heart strain (on ECG S1Q3T3)
what is the lifetime risk of a VTE
2.5%
highest when eldery/ pregnant/ post natal
what are the risk factors for VTE IN EXAMS
(anything that causes stasis, vessel wall damage or hypercoagulability)
age marked obesity pregnancy puerperium oestrogen therapy previous DVT/ PE trauma/ surgery malignancy paralysis infection thrombophilia
what can cause stasis
age
obesity
pregnancy (gravid uterus can compress on veins)
previous DVT/PE
trauma/ surgery (esp lower limb orthopaedic)
malignancy
paralysis
what are the common causes of vessel wall damage
age
previous DVT/PE
what causes hypercoagulabilty
anything that causes infection of inflammation: age pregnancy and puerperium (oestrogen and CF 8 rise physiologically to prevent harmorrhage) osterogen therapy trauma/ surgery malignancy infection thrombophilia
what component of haemostasis is a VTE usually caused by
failure of anticoagulant defences
hypercoagulability causes the release and increase of what factors
release of tissue factor
raised VWF and CF 8
fibrinogen and other CF also activated
what is thrombophilia
familial or acquired disorders of the haemostatic mechanism which are likely to predispose to thrombosis
what are the potential mechanisms of thrombophilia
decreased anticoagulant activity (most common)
increased coagulation (platelet plug/ fibrin clot formation)
decreased fibrinolytic activity
what does the bodys anticoagulant activity do
switches off 2nd haemostasis
what are naturally occurring anticoagulants
serine protease inhibitors (anti-thrombin)
protein C and protein S (switch off CF 5 and 8)
what is the most common inherited thrombophilia
factor 5 leiden
what are hereditary thrombophilias
group of genetic defects in which affected individuals have an increased tendancy to develop premature, unusual and recurrent thrombosis
what are the types of hereditary thrombophilia
factor 5 leiden (5x risk) prothrombin 20210 (2x risk) antithrombin def protein C def protein S def
when should you consider hereditary thrombophilia screening
VTE <45 y/o recurrent VTE unusual VTE (e.g. in upper limb) FHx of VTE FHx of thrombophilia
what is the management of hereditary thrombophilia
advice on risk avoidance
short term prophylaxis (during periods of known risk)
short term anticoagulation (to treat thrombotic events)
long term anticoagulation (if recurrent thrombotic events)
will everyone with hereditary thrombophilia have a thrombosis
most will never
lots of other influences e.g. RFs
what do you need to consider in long term anticoagulation
risk of recurrent thrombosis
vs
risk of serious haemorrhage
(warfarin annual rate of ICH 1 in 200)
what is the most important thing in assessing risk of recurrent thrombosis
history of previous thrombosis
spontaneous thrombosis rather than acquired transient risk factor (immobility/ surgery)
FHx
thrombophilia screen results
name an acquired thrombophilia
antiphospholipid syndrome
does hereditary thrombophilia or APS have a bigger risk for thrombosis
APS
what is APS
autoimmune condition with antibodies against beta2 glycoprotein 1 which causes activation of primary and secondary haemostasis and vessel wall abnormalities
(get arterial- platelets- and venous- fibrin- clots)
what are the features of APS
recurrent thrombosis:
- arterial (common cause of TIA/ stroke in young)
- venous
recurrent fetal loss (thrombosis in placenta)
mild thrombocytoenia (can have ITP like condition due to cross reactivity of antibody)
what are the antiphospholipid antibodies
lupus anticoagulants
have specificity for anionic phsophlipids which prolong phosholipid dependent coagulation in vitro (APTT prolonged)
what conditions are associated with antiphospholipid antbodies
autoimmune disorders lymphoproliferative disorders (chronic lymphocytic leukaemia) viral infections (EBV) drugs primary
what is the treatment of APS
as activation of 1st and 2nd haemostasis get arterial and venous thrombosis so need aspirin (aterial) and warfarin (vein) (if given in pregnancy with APS drastically increase chance of live birth)
(warfarin preffered over NOACs as has some protection against arterial events too)
