Venous thromboembolism Flashcards
What is the difference between a venous and an arterial thrombus?
Venous thrombus: red cells trapped in a fibrin meshwork
Arterial thrombus: platelets trapped in fibrin meshwork
Where do the majority of DVTs arise? What complications are associated with DVT?
Majority arise in calf venous sinuses
Can result in PEs
20% of DVTs are fatal
Other complications:
- extension of clot
- recurrent VTE
- post thrombotic syndrome: recurrent pain + swelling
- –> result of venous hypertension
What is Virchow’s triad?
3 factors that cause VTE:
- reduced blood flow (stasis)
- vessel wall disorder
- hypercoagulability
What are the risk factors for VTE?
- Genetic:
- antithrombin deficiency
- protein C+S deficiency
- Factor V leiden
- Elevated factor VII, IX and XI - Environmental:
- surgery
- trauma
- immobilisation
- pregnancy
- hormonal therapy
- travel - Acquired:
- age
- cancer
- antiphospholipid
- infections
- obesity
- smoking
Describe how DVTs usually present.
- Usually unilateral*
- Pain
- erythema
- tenderness
- swelling
- palpable cord (thrombosed vein)
- warmth
- ipsilateral oedema
- superficial venous dilation
What are the differential diagnoses for DVT?
- Musculotendinous: trauma, haematoma
- Congestive heart failure
- Compression of iliac veins
- Lymphoedema
- Acute arterial occlusion
- Post-thrombotic syndrome
- Ruptured baker’s cyst
How is DVT diagnosed? (besides clinical presentation)
- D-dimer test: increased value = increased thrombolysis = clot present
- radiological assessment: compression US, venography (gold standard), CT can be used
- Wells Score (>2 = DVT likely)
State the criteria in Wells score for DVT.
- active cancer (<6 months) = +1
- paralysis, paresis = +1
- bedridden >3 days = +1
- localised tenderness along deep veins = +1
- entire leg swollen = +1
- calf swelling >3cm = +1
- pitting oedema = +1
- collateral superficial vein = +1
- previous DVT = +1
- alternative diagnosis just as likely = -2
How does pulmonary embolism present/what are the signs?
Presentation:
- pulmonary infarct/haemorrhage –> breathlessness, pleuritic chest pain, haemoptysis
- isolated breathlessness
- collapse, syncope
Signs:
- tachypnoea
- tachycardia
- crepitations
- pleural rub
What might a PE look like on an ECG?
- sinus tachycardia
- right heart strain
- t wave inversion (anterior leads, V4 + V4)
- S1Q3T3 pattern
What might a PE look like on a CXR?
Often normal
- focal oligaemia
- small pleural effusion
- wedge shaped density above diaphragm
What would material blood gases in PE show?
Hypoxia
Hypercapnia
What are the differential diagnoses for PE?
- COPD exacerbation
- Pneumonia/bronchitis
- Acute coronary syndrome
- Pneumothorax
- Musculoskeletal pain/rib fracture
- Pulmonary hypertension
- Lung cancer
- Pericaridal tamponade
- Dissection of aorta
- Anxiety
- Asthma
How is PE diagnosed? (besides clinical presentation)
- CT pulmonary angiogram
- Isotope lung scan (normal lung scan will exclude PE)
- Echocardiogram
- Leg US if symptomatic
- D-dimer
- Wells Score (>/=4 = PE likely)
State the criteria for Wells Score in PE.
- Clinical signs of DVT = +3
- Alternative diagnosis is less likely = +3
- Pulse >100 = +1.5
- Immobilisation or surgery = +1.5
- Previous DVT or PE = +1.5
- Haemoptysis = +1
- Cancer (last 6 months) = +1
