Venous Thrombosis Flashcards
types of arterial thrombotic events?
coronary
cerebral
peripheral
types of venous thrombotic events?
DVT
PE
artery vs vein?
artery has thicker muscle
artery actually pulsates itself
blood pumped through vein via contraction of surrounding muscles
what usually causes arterial thrombosis?
atherosclerosis leading to a platelet rich thrombus if plaque ruptures exposing collagen etc
treatment of arterial thrombosis?
aspirin and other anti-platelets
modify risk factors
what tends to be the problem causing venous thrombosis?
blood stasis (platelets not activated) static blood tends to congeal and form a fibrin clot via the coagulation cascade
management of venous thrombosis?
target fibrin formation
warfarin, anticoagulants etc
virchows triad of cause of venous thrombosis?
venous stasis
damage to vessel wall (deterioration of valves due to age, previous clots etc)
hypercoagulable blood (elevated clotting factors due to illness or inherited low levels of naturally occurring anticoagulants such as protein C and S and antithrombin)
features of DVT?
limb feels hot, swollen and tender
pitting oedema
high WCC
signs of PE?
pleuritic chest pain tachypnoea tachycardia hypoxia cardiovascular collapse/death right heart strain on ECG
risk factors for venous thromboembolism?
age (damaged vessels and lack of mobility) obesity pregnancy puerperium(6 weeks following childbirth) oestrogen therapy previous DVT/PE (damages vessel wall) trauma/surgery malignancy paralysis infection thrombophilia anything that cause reduced mobility
stasis related risk factors?
age obesity pregnancy previous DVT/PE trauma/surgery malignancy paralysis
vessel wall related risk factors?
age
previous DVT/PE
hypercoagulability related risk factors?
age pregnancy (increased CFs and oestrogen) puerperium oestrogen therapy (increases CFs) trauma/surgery malignancy infection thrombophilia (increased TF, vWF and CF 8)
what part of haemostatic system tends to go wrong in thrombophilia?
anticoagulant defences
what is thrombophilia?
familial acquired disorders of the haemostatic mechanism which are likely to predispose to thrombosis
potential mechanisms of thrombophilia?
decreased anticoagulant activity increased coagulation (antiphospholipid syndrome)
what are the naturally occurring anticoagulants which can be deficient in families?
anti-thrombin (type of serine protease inhibitor)
protein C and protein S (factor 5 leiden can reduce ability of protein C and S to switch off CF 5)
what is hereditary thrombophilia?
group of genetic defects in which affected individuals have an increased tendency to develop premature unusual and recurrent thrombosis
causes of hereditary thrombophilia?
presence of factor 5 leiden prothrombin 20210 mutation antithrombin deficiency protein C deficiency protein S deficiency
when would a diagnosis of hereditary thrombophilia 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 to avoid risk
short term prophylaxis during periods of known risk
short term anticoagulation to treat thrombotic events
long term anticoagulation if recurrent thrombotic events
when does a thrombotic event become likely in thrombophilia?
when there are multiple risk factors
often never have an event if no other risk factors are present
risks of recurrent thrombosis in order of highest-lowest risk?
history of previous DVT/PE
spontaneous thrombosis rather than acquired risk factor (e.g immobility or surgery etc)
family history
thrombophilia screen results
risk of thrombosis in antiphospholipid syndrome?
stronger risk factor than hereditary thrombophilia
features of antiphospholipid syndrome?
recurrent arterial and venous thromboses (including TIA)
recurrent foetal loss
mild thrombocytopaenia
pathogenesis of antiphospholipid syndrome?
antibodies lead to a conformational change in beta 2 glycoprotein 1 which leads to activation of both primary and secondary haemostasis and vessel wall abnormalities
describe the antibodies in antiphospholipid syndrome
autoantibodies which have specificity for anionic phospholipids
also prolong phospholipid dependant coagulation tests in vitro (prolongs ATPP test even though there isn’t a clotting factor deficiency)
also known as lupus anticoagulants
conditions associated with antiphospholipid antibodies?
autoimmune disorders lymphoproliferative disorders viral infection drugs primary
management of antiphospholipid syndrome?
aspirin (venous thrombosis)
warfarin (arterial thrombosis)
