Venous Thrombosis Flashcards
what does an arterial thrombotic event lead to
Coronary thrombosis (MI)
Cerebral (stroke)
Peripheral
what does a venous thrombotic event lead to
DVT
Pulmonary embolism
what leads to blood clots in arteries
atherosclerosis
cholesterol plaque builds up in artery narrowing it and causing hypoxia (angina, claudication pain)
atherosclerotic plaque ruptures and exposes collagen
collagen attracts platelets, platelet clot comes and completely occludes the vessel leading to complete tissue infection (platelet rich thrombus)
how do you treat arterial thrombosis
aspirin and other anti-platelet drugs
modify risk factors for atherosclerosis
causes of venous thrombosis
low pressure system - stasis problem, blood sits there and congeals and forms a fibrin clot
coagulation cascade activated which is rich in FIBRIN CLOT
treatment of venous thrombosis
anticoagulants - warfarin, heparin, new oral anticoagulants
what is Virchow’s triad in venous thrombosis
Stasis (blood not moving)
Vessel wall (deterioration of the valves in the vessels, caused by age, or previous clot)
Hypercoagulability (elevated levels of clotting factors eg, in acute response if unwell makes you more prone to forming blood clots) OR low levels of natural anti-coagulants (protein S, protein C)
presentation of deep vein thrombosis
limbs feel hot
swollen
tender
pitting oedema
how can DVT cause PE
clot goes up through IVC, into right side of the heart and then through into the lungs
Blood clot gets stuck in the smaller vessels of the lungs blocking off the venous blood supply
presentation of PE
pleuritic chest pain (every time you take a breath the lung irritates the pleura causing acute pain)
cardiovascular collapse/death
Right sided heart strain on ECG - backing up of blood into the right side of the heart?
Hypoxia
risk factors for venous thromboembolism (STASIS)
Stasis:
- age
- obesity
- pregnancy
- previous DVT/PE
- trauma/surgery
- malignancy
- paralysis
Risk factors for venous thrombosis (VESSEL WALL)
vessel wall:
- age
- previous DVT/PE
risk factors for venous thrombosis (hYPERCOAGULABILITY)
- age
- pregnancy (increased clotting factors in pregnancy to prevent haemorrhage in birth)
- puerperium
- oestrogen therapy (same problems as pregnancy)
- trauma/surgery
- malignancy
- infection
- thrombophilia
what goes wrong in normal haemostatic system to increase change of thrombophilia
decreased anticoagulant defences
increased coagulation activity (not common, antiphospholipid syndrome)
decreased fibrinolysis (rare)
what is thrombophilia
familia or acquired disorders of the haemostasis mechanism which are more likely to predispose to thrombosis
what does anti-thrombin do
Serine protease inhibitor
binds to thrombin and switches it off
(if anti-thrombin deficiency you’re at much higher risk of thrombosis)
what do proteins C and S do
switch off factor V and factor Xa
factor V leiden is a problem in switching off factor 5 - causes 5x risk of thrombosis
what are hereditary thrombophilias
group of genetic defects in which theres an increased tendency to develop premature unusual and recurrent thrombosis
what are the hereditary thrombophilia’s
Factor V Leidin Prothrombin 20210 mutation Antithrombin deficiency Protein C deficiency Protein S deficiency
when would you screen for hereditary thrombophilia
Venous thrombosis <45 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 thrombotic events in times of increased risk)
Short term anticoagulation (to treat thrombotic events)
Long term anticoagulation (if recurrent thrombotic events)
why do some people with thrombophilia never have a thrombosis
because to have a thrombotic event a number of risk factors have to go together
not necessarily enough to just have the thrombophilia but if thrombophilia + another risk factor eg. OCP = thrombosis
what has to be balanced when considering long term anticoagulation
risk of recurrent thrombosis vs risk of serious haemorrhage
causes of ACQUIRED thrombophilia
antiphospholipid antibody syndrome
stronger risk factor for thrombosis than hereditary thrombophilias
how does antiphospholipid syndrome present
recurrent thrombosis
(arterial, including TIAs AND venous)
recurrent fetal loss (thrombosis in the placenta)
mild thrombocytopenia
what do anti-phospholipid antibodies do
causes a conformational change in b1 glycoprotein 1
causes activation of both primary and secondary Haemostasis and vessel wall abnormalities
antibodies interfere with tests giving false positive clotting factor tests (APTT prolonged but not prone to bleeding, prone to clotting)
conditions associated with antiphospholipid antibodies
autoimmune disorders lymphoproliferative disorders viral infections drugs primary
treatment of anti-phospholipid syndrome
Aspirin
Warfarin
(need to treat both primary and secondary homeostasis)
