Thrombosis and Anticoagulation Flashcards
what is thrombosis?
blood coagulation inside a vessel
describe appropriate coagulation
when blood escapes a vessel, failure of coagulation in this situation leads to bleeding
when can thrombosis occur?
arterial circulation: high pressure: platelet rich
venous circulation: low pressure fibrin rich
symptoms of arterial thrombosis in coronary circulation
pain in left arm
angina
symptoms of arterial thrombosis in cerebral circulation
slurred speech, headaches
symptoms of arterial thrombosis in peripheral circulation
pain in leg
symptoms of arterial thrombosis in Superior mesenteric artery
belly ache
what are the underlying causes of arterial thrombosis in most cases?
–Atherosclerosis
-Inflammatory
-Infective
-Trauma
-Tumours
-Unknown
-Platelet driven
what are the presentations of arterial thrombosis?
-Myocardial infarction
-CVA
-Peripheral vascular disease
-Others
what are the treatments for arterial thrombosis in the coronary circulation ?
Coronary:
-Aspirin other antiplatelets
-LMWH or Fondaparinux or UFH
-Thrombolytic therapy: streptokinase tissue plasminogen activator
-Reperfusion – Catheter directed treatments and stents
-Aspirin inhibits platelet function
TPA generates plasmin, degrades fibrin
Why is Fondaparinux used instead of heparin?
Fondaparinux- used to prevent clotting
much higher risk of bleeding with heparin than fondaparinux- also has a much higher half life than heparin
what is the treatment of arterial thrombosis in the cerebral circulation?
-Aspirin,
-other anti-platelets
Thrombolysis
-Catheter directed treatments
Reperfusion
Why is heparin not used in cerebral circulation?
too much bleeding
what is the treatment of arterial thrombosis in other sites?
Antiplatelets, statins
Role of anticoagulants evolving
Endovascular vs Surgical
where does deep vein thrombosis occur peripherally?
Peripheral –Ileofemoral, femoro-popliteal
between ivc and popliteal vein
what are the non specific symptoms for venous thrombosis?
calf pain
chest pain
breathlessness
pulled muscle
groin strain
what are things that can change blood flow in virchows triad?
Immobilisation
-Surgery
-Long haul flights
-Trauma
what are things that can change endothelium in virchows triad?
Injury – physical, chemical
what are things that can change blood constituents genetically in virchows triad?
Factor V Leiden (5%)
PT20210A (3%)
Antithrombin deficiency
Protein C deficiency
Protein S deficiency
what are the components of virchows triad?
blood constituents
blood flow
endothelium
what are things that can change blood constituents acquired in virchows triad?
-Anti-phospholipid syndrome
-Lupus anticoagulant
–Hyperhomocysteinaemia
what is the main treatment for venous thrombosis?
- heparin or LMWH
-Warfarin - DOAC- direct oral anti coagulation- only once daily- don’t have to monitor
-endovascular- catheter inserted into vein
-surgical - very rare
how is venous thrombosis prevented?
-Mechanical or chemical thromboprophylaxsis
-Also early mobilisation and good hydration
describe heparin
heparin is given IV via a canula on a continuous infusion- measured with various ratios/ APTT depending on why given medication
- short half life
what does heparin do?
-Binds to antithrombin and increases its activity
-Indirect thrombin inhibitor
what is the difference with low molecular weight heparin?
-smaller molecule, less variation in dose and renally excreted
-Once daily, weight-adjusted dose given subcutaneously
-Used for treatment and prophylaxsis
describe warfarin
- orally active
-Antagonist of vitamin K
Long half life (36 hours)
what does warfarin do?
-Prevents synthesis of active factors II, VII, IX and X
-Prolongs the prothrombin time
drawbacks of warfarin
-Difficult to use,
-Individual variation in dose
-Need to monitor
-Measure INR (international normalised ratio, derived from prothrombin time)
describe DOAC
Orally active
Directly acting on factor II or X
No blood tests or monitoring
Shorter half lives so bd or od
Not used in pregnancy
when is DOAC used?
Used for extended thromboprophylasis and treatment of AF and DVT/PE
describe fondaparineux
Pentasaccharide
Indirect Xa inhibitor
what does aspirin do?
-Inhibits cyclo-oxygenase irreversibly
-Act for lifetime of platelet, 7-10 days
-Inhibits thromboxane formation and hence platelet aggregation
-Used in arterial thrombosis, 75-300 mg od
symptoms of DVT
leg pain, swelling
signs of DVT
tenderness, swelling, warmth, discolouration
complications of DVT
Phlegmasia Alba Dolens and Phlegmasia Cerulae Dolens, PE
What are the investigations done for DVT?
-D-dimer: normal excludes diagnosis positive does not confirm diagnosis
Ultrasound compression
CT or MR venogram
catheter venogram?
DVT treatments
-LMW Heparin (for min 5 days)
-Oral warfarin (INR 2-3) for 3-6 months
-Or DOAC/NOAC
-Compression stockings – symptoms vs PTS
-Treat/ seek underlying cause
describe re- canalisation - endovenous
Chemical
Mechanical
Mechanico-chemical
Stents
how are dvt prevented?
Mechanical- hydration and early mobilisation, Compression stockings, Foot pumps
Chemical- LMW Heparin
symptoms of pulmonary embolism
breathlessness, pleuritic chest pain
symptoms of DVT
risk factors for DVT
signs of pulmonary embolism
tachycardia, tachypnoea, pleural rub,
Signs of DVT
how are pulmonary embolisms treated?
Supportive treatment
LMW Heparin
Oral warfarin (INR 2-3)for 6 months
DOAC/NOAC
Treat underlying cause
how is PE prevention/
Anticoagulation
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