Week 3- venous thrombosis Flashcards
Describe an arterial thrombosis?
Its a platelet rich atherosclerotic plaque. The vessel wall is injured, LDL cholesterol builds up in it. Platelets adhere to it.
How do you treat arterial thrombosis?
Aspirin and other anti-platelet drugs
Modify risk factors for atherosclerosis.
Describe a venous thrombosis?
Platelets are not activated in this type of clot. Its a fibrin rich clot due to activation of the coagulation cascade.
What makes up virchows triad?
Stasis
Hypercoagulability
Vessel wall (endothelial) damage
What is the treatment for venous clots?
Heparin/warfarin and newer oral anticoagulants.
Why does valvular failure cause blood clots?
Valvular failure leads to blood pooling, which leads to stasis which leads to blood clotting.
Name some examples of patients in hypercoagulable states?
Hypercoagulable = high levels of clotting factors in the blood.
Oral contraceptive pill, pregnancy, high oestrogen states.
Symptoms of a DVT
Limb is swollen, hot and tender.
Pitting oedema
Symptoms of a pulmonary embolism
Sharp stabbing pain (pleura rub together its incredibly sore)
Hypoxic
Heart cant pump the blood to the lungs,
Pulmonary infarction causes this.
Risk factors for VTE
Old age
Obesity
Pregnancy
Peurperium
Oestrogen therapy
Previous DVT/PE
Trauma/surgery
Malignancy
Paralysis
Infection
Thrombophillia
Which of the risk factors cause stasis?
Age
Marked obesity
Pregnancy
Previous DVT/PE
Trauma/surgery
Malignancy
Paralysis
Which of the risk factors cause vessel damage?
Age
Previous DVT/PE
Which of the risk factors cause hypercoagulability?
Age
Pregnancy
Peurperium
Oestrogen therapy
Trauma/surgery
Malignancy
Infection
Thrombophillia
What is hypercoagulability associated with?
Release of tissue factor, raised VWF and factor VIII.
What is thrombophillia?
Familial or acquired disorders of the haemostatic mechanism which are likely to predispose to thrombosis.
What can thrombophillia be due too?
Can be due to the lack of naturally occuring anticoagulants e.g. antithrombin or protein c and protein s.
What sort of clots are thrombophillia sufferers likely to have?
Venous thrombosis.
What is factor V leiden?
Factor V works completely normally however doesnt respond to switching off from Protein C and Protein S.
Describe hereditary thrombophillias?
A group of genetic defects in which affected individuals have an increased tendancy to develop premature, unsual and recurrent thrombosis.
Give examples of hereditary thrombophillias?
Factor V Leiden
Prothrombin 20210 mutation
Antithrombin deficiency
Protein C deficiency
Protein S deficiency
When should you consider screening for hereditary thrombophillias?
Venous thrombosis<45 years old
Recurrent venous thrombosis
Unusual venous thrombosis (cerebral veins or upper limb)
Family history of venous thrombosis
Family history of thrombophillia
How do you manage hereditary thrombophillias?
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 occur.
This explains how risk factors can affect the risk of thrombosis.
What is the toss up with long term anticoagulation?
Risk of recurrent thrombosis vs risk of serious haemorrhage.
What is more important, the clinical history or the results of thrombophillia screening?
Clinical history is much more important- need to pay attention to:
- History of previous thrombosis
- Spontaneous thrombosis rather than acquired transient RF e.g. immobility due to surgery
- Family history
- Thromobphillia screening results.
Name an acquired thrombophillia?
Is it more or less likely to cause thrombosis than the hereditary ones?
Antiphospholipid syndrome
More likely to cause thrombosis.
What are the features of antiphospholipid syndrome?
Recurrent thromboses (both arterial and venous- could be Hx of TIAs. This is due to it activating both primary and secondary haemostasis)
Recurrent fetal loss
Mild thrombocytopenia
Describe the pathogenesis of antiphospholipid syndrome?
Antibodies lead to a conformational change in beta 2 glycoprotein 1 (a protein with unknown function in health) which leads to activation of both primary and secondary haemostasis and vessel wall abnormalities.
Describe the antibodies in antiphospholipid syndrome?
They are autoantibodies with a specificity for anionic phospholipids and which prolong phospholipid dependent coagulation tests in vitro
Also called lupus anticoagulants.
What conditions are associated with antiphospholipid syndrome?
Autoimmune disorders
Lymphoproliferative disorders
Viral infections
Drugs
Primary
How do you treat anti-phospholipid syndrome?
It depends on how its presented, if venous thrombosis give warfarin, if arterial give aspirin. if both, give both.
