Thrombosis, ischaemia, embolism and infarction Flashcards
What is the definition of thrombosis?
A condition in which the blood changes from a liquid to a solid within the CV system and produces a mass of coagulated blood
What is the role of von Willebrand factor in primary haemostasis?
Binds to other proteins (particularly factor VIII)
- acts as a carrier, improving the half life
Acts as a bridging molecule for normal platelet adhesion
Promotes platelet aggregation
What is Virchow’s triad?
Describes three broad categories of factors that are thought to contribute to thrombosis
- hypercoagulability
- haemodynamic changes
- endothelial injury/dysfunction
What is the difference between arterial and venous thrombosis?
Arterial
- ‘white thrombus’
- many platelets with small amounts of fibrin due to high flow
Venous
- ‘red thrombus’
- many fibrin with trapped red cells due to indolent flow
What are the differential diagnoses for a sore leg?
Trauma
- fractures, disolcations, muscle strain
Non-traumatic
- MSK causes, oesto, rheumatoid or septic arthritis, gout, Baker’s cyst, bursitis
Skin/soft tissue infections
- cellulitis, erysipelas, abscesses, necrotising fasciitis
Vascular causes
- venous occlusion (DVT, superficial vein thrombosis, venous insufficiency)
- acute ischaemia (cardia thromboembolism, PAD)
- lymphoedema
Bilateral swelling
- systemic oedema (Heart failure, cirrhosos, nephrotic syndrome)
Where is a DVT most likely to occur?
The leg
Are you more likely to get a deep vein thrombosis or a superficial vein thrombosis?
DVTs make up 2/3rds of all venous thrombosis
What are the risk factors for DVT?
Vessel wall
- increasing age, varicose veins, surgery
Blood flow
- obesity, pregnancy, immobilisation, IV catheters, external vein compression
Composition of the blood
- thrombophilias (including family history). inflammatory conditions, oestrogen hormones
How is a DVT diagnosed?
Clinical decision
- determination of likelihood (risk factors)
Blood tests
- fibrin D-dimer, a measure of dissolved thrombus
Imaging
- compression ultrasound, venography
Describe the components of the Wells clinical scoring system.
All worth one mark
Active cancer
Paralysis or recent plaster immobilisation of lower extremities
Recently bed ridden, or recent surgery (12 weeks)
Entire leg swollen
Calf swollen 3cm or more than the other leg
Pitting oedema
Collateral superficial veins
Previous DVT
Alternative diagnosis more likely than DVT (-2)
What score on the Wells clinical scoring system suggest DVT/PE?
2 or more
What are the possible outcomes following a DVT?
Painful swollen leg Pulmonary embolism - 50% of cases Recurrent VTE - 20-30% at 10 years Venous insufficiency - 40-60% have residual thrombus on US at 6-12 months Post thrombotic syndrome - 25% at 2 years - increased risk if DVT is recurrent - compression stockings reduce risk
What are the possible outcomes following a PE?
Dyspnoea, chest pain, haemoptysis Collapse Death - 90% diagnosed PM - 0.6% risk after DVT Recurrent VTE Chronic thromboembolic pulmonary hypertension - risk increases if PE is recurrent
How is a DVT treated?
Prevent thrombus extending or embolising
- anticoagulant for 3-6 months
- heparin (LMWH)
- warfarin
- direct oral anti-coagulant (direct Xa or IIa inhibitor)
Remove risk factors
Pain relief
Gradual elastic compression stockingsHow are VTEs prevented?
Avoid risk factors
Risk assess at hospital admission or surgery
Provide thrombo-prophylaxis when appropriate
- anti-embolism stockings
- heparin (LMWH daily sub cut)
Educate patients on risk and avoidance measures
- early mobilisation
