Venous Thrombosis Flashcards
What is involved in arterial thrombosis?
High pressure system
Atherosclerosis
Platelet rich thrombus
How is arterial thrombus treated?
Aspirin and other anti platelet drugs
Modify RFs for atherosclerosis
What is involved in venous thrombosis?
Low pressure system
Platelets not activated
Activates coagulation cascade- rich in fibrin clot
What is Virchow’s triad?
Stasis
Vessel wall- endothelial injury
Hypercoagulability
How is venous thrombosis treated?
Heparin/warfarin/ new oral anticoagulants
What are the clinical features in DVT?
Limbs feel hot, swollen, tender
Pitting oedema
What can a PE cause?
Pulmonary infarction Pleuritic chest pain Cardiovascular collapse/death Hypoxia Right heart strain
What is the risk of having a VTE?
1/1000/annum
Young adults 1/10000/annum
Elderly 1/100/annum
Lifetime risk 2.5%
What are RFs for VTE?
Age Marked obesity Pregnancy Puerperium Oestrogen therapy Previous DVT/PE Trauma/Surgery Malignancy Paralysis Infection Thrombophilia
What RFs are associated with stasis?
Age Marked obesity Pregnancy Previous DVT/PE Trauma/surgery Malignancy Paralysis
What RFs are associated with vessel wall injury?
Age
Previous DVT/PE
What RFs are associated with hypercoagulability?
Age Pregnancy Puerperium Oestrogen therapy Trauma/surgery Malignancy Infection Thrombophilia
What are the RFs related to hypercoagulability associated with?
Release of TF, raised vWF and factor VIII
What is thrombophilia?
Familial or acquired disorders of the haemostatic mechanism which are likely to predispose to thrombosis.
What are the possible mechanisms of thrombophilia?
Increased coagulation activity- Platelet plug formation, fibrin clot formation
Decreased fibrinolytic activity
Decreased anticoagulant activity
What are the hereditary thrombophilias?
A group of genetic defects in which affected individuals have an increased tendancy to develop premature, unusual and recurrent thromboses
What can cause a hereditary thrombophilia?
Factor V Leiden Prothrombin 20210 mutation Antithrombin deficiency Protein C deficiency Protein S deficiency
When should you consider hereditary thrombophilia screening?
Venous thrombosis <45 years old Recurrent venous thrombosis Unusual venous thrombosis Family history of venous thrombosis Family history of thrombophilia
How should you manage hereditary thrombophilia?
Advice on avoiding risk
Short term prophylaxis to prevent thrombotic events during periods of known risk
Short term anticoagulation to treat thrombotic events
Long term anticoagulation if recurrent thrombotic events
How should risk of recurrent thrombosis be evaluated?
History of previous thrombosis
Spontaneous thrombosis rather than acquired transient risk factor (eg immobility or surgery)
Family history
Thrombophilia screen results
(Clinical history much more important than results of screening)
What can cause acquired thrombophilia?
Antiphospholipid antibody syndrome
Is antiphospholipid antibody syndrome a stronger RF for thrombosis than the hereditary thrombophilias?
Yes
What are some features of antiphospholipid antibody syndrome?
Recurrent thromboses- Arterial, including TIAs, Venous
Recurrent fetal loss
Mild thrombocytopenia
What is the pathogenesis of antiphospholipid antibodies?
Antibodies lead to a conformational change in β2 glycoprotein 1 (a protein with unknown function in health) which leads to activation of both primary and secondary haemostasis and vessel wall abnormalities
What are antiphospholipid antibodies?
Autoantibodies which have specificity for anionic phospholipids and which prolong phospholipid dependant coagulation tests in vitro
Also known as Lupus anticoagulants
What conditions are associated with antiphospholipid antibodies?
AI Disorders Lymphoproliferative disorders Viral infections Drugs Primary
What is the treatment of anti-phospholipid syndrome?
Aspirin
Warfarin
