Deep Vein Thrombosis & Pulmonary Embolism - Presentation, Investigation & Therapy Flashcards
What is thrombosis?
The formation of a thrombus
What is the formation of a thrombus called?
Thrombosis
What is a thrombus?
Blood clot that forms in a vessel and remains there
What is a blood clot that forms in a vessel and remains there called?
Thrombus
Where can a thrombus be present?
Artery
Vein
What is a clot made up of?
Fibrin
Platelets
Red blood cells
What catalyses the reaction of fibrinogen to fibrin?
Thrombin
What catalyses the reaction of thrombin to prothrombin?
Tissue factor V
How does the mechanism of arterial thrombus differ from venous?
Arterial is usually due to rupture of atherosclerotic plaque
Venous is usually a combination of Virchow’s triad (especially stasis and hypercoagulability)
What do arterial thrombus result in?
Ischaemia and infarction
What do venous thrombus result in?
Back pressure
What diseases can arterial thrombus lead to?
Acute coronary syndrome
Ischaemic stroke
Limb claudication/ischaemia
What diseases can venous thrombus lead to?
Deep vein thrombosis
Pulmonary embolism
What is the composition of an arterial thrombus?
White thrombus (platelets and fibrin)
What is the combination of a venous thrombus?
Red thrombus (red blood cellsa and fibrin)
What is Virchow’s triad?
The factors that leads to thrombosis
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What are some risk factors for the stasis aspect of Virchow’s triad?
Immobility
Long haul travel
What are some risk factors for the vessel damage aspect of Virchow’s triad?
Endothelial dynsfunction (hypertension, smoking)
Endothelial damage (trauma, surgery)
What are some risk factors for the hypercoagulability aspect of Virchow’s triad?
Pregnancy
Cancer
Sepsis
What is an embolism?
Intravascular material that migrates from its original location to a distal vessel
What is intravascular material that migrates from its original location to a distal vessel called?
Embolism
What are examples of different embolus?
Blood clot
Fat
Air
Tumour
What is a thromboembolism?
Movement of a blood clot along a vessel
What is movement of a blood clot along a vessel called?
Thromboembolism
What does VTE stand for?
Venous thromboembolism
What are some examples of venous thromboembolism?
Limp deep vein thromboembolism
Pulmonary embolism
Visceral venous thrombosis
Intracranial venous thrombosis
What does PE stand for?
Pulmonary embolism
What does DVT stand for?
Deep vein thrombosis
What is the prevalence of DVT?
1/1000
What is the prevalence of pulmonary embolism?
1/3000
What is the leading cause of direct maternal death in the UK?
Venous thromboembolism
What is the fatality rate of untreated pulmonary embolism?
30%
What are some risk factors for venous thromboembolism?
Surgery
Fracture
Hypertension
Cardiac failure
Obesity
What are some symptoms and signs for deep vein thrombosis?
Unilateral limb swelling
Persisting discomfort
Calf tenderness
Warmth
Redness
Prominent collateral veins
Unilateral pitting oedema
May be clinically silent
What are some potential long term consequences of deep vein thrombosis?
Post thrombotic syndrome (damage to venous valves)
What is the incidence of post thrombotic syndrome?
20-60% within 2 years of deep vein thrombosis
What are the symptoms of post thrombotic syndrome (damage to venous valves)?
Swelling
Discomfort
Pigmentation
Ulceration in severe form
What is used to diagnose deep vein thrombosis?
Clinical assessment and pre-test probability score (Well’s score)
Blood tests (D-dimer if low pre-test probability score)
Imaging (compression ultrasound if positive D-dimer or high pre-test probability score)
What scoring system is used to diagnose deep vein thrombosis?
Well score
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What well score is a high probability of DVT?
More than or 3
What wells score is a moderate probability of deep vein thrombosis?
1 or 2
What wells score is a low probability of deep vein thrombosis?
Less than or 0
What is D-dimer?
Breakdown product of cross-linked fibrin (produced during fibrinolysis)
What is fibrinolysis?
Breakdown of fibrin in blood clots
What is breakdown of fibrin in blood clots called?
Fibrinolysis
What are some symptoms and signs of pulmonary embolism?
Pleuritic chest pain
Dyspnoea
Haemoptysis
Tachycardia
Pleural rub on auscultation
What are symptoms and signs of massive pulmonary embolism?
Severe dyspnoea of sudden onset
Collapse
Cyanosis
Tachycardia
Low blood pressure
Raised jugular venous pressure
Sudden death
What is used for the diagnosis of pulmonary embolism?
Clinical assessment and pre-test probability (Wells score)
Blood test (D-dimer if low pre test probability)
Imaging, perfusion scan or CT pulmonary angiogram (if D-dimer positive or high pre-test probability score)
What imaging is used to diagnose pulmonary embolism?
Perfusion scan
CT pulmonary angiogram
What Wells score is a high probability for pulmonary embolism?
More than or equal to 6.5
What Wells score is a moderate probability for pulmonary embolism?
4.5-6
What Wells score is a low probability for pulmonary embolism?
Less than or equal to 4
What are potential long term consequences of pulmonary embolism?
Most recover fully
Pulmonary arterial hypertension
What are the aims of treatment for venous thromboemolism?
Prevent clot extension
Prevent clot embolism
Prevent recurrent clot
What are the treatment options for venous thromboembolism?
Anticoagulatation (main treatment)
Thrombolysis (reserved for massive pulmonary embolism)
What are examples of anticoagulants?
Unfractionated heparin
Low molecular weight heparin
Warfarin
Direct oral anticoagulants (DOACs)
What is an example of a thrombolysis?
Alteplase
How is venous thromboembolism prevented in hospital?
Early mobilisation
Anti-embolism stockings
Other mechanical methods of thromboprophylaxis
Pharmacological thromboprohylaxis
What can develop after a pulmonary embolism?
Pulmonary infarction
What is the process of pulmonary embolism leading to pulmonary infarction?
1) Blockage to a branch of the pulmonary artery causes increase in pressure within pulmonary vasculature
2) Force within bronchial artery must be sufficient to overcome this
3) Leakage of blood into alveolar space occurs and leads to infarction
Why is pulmonary infarction?
Dual vascular supply to the lungs with anastomoses
What is the dual vascular supply to the lungs composed of?
Pulmonary vascular system
Bronchial vascular system
What vascular system supplies the majority of O2 to the lung parenchyma?
Bronchial vascular system
Where do the pulmonary and bronchial vascular systems anastomoses?
Pre and post capillary