DVT and PE: Venous thromboembolism Flashcards
What is a thrombus composed of?
Fibrin
Platelets
RBC
How do a thrombus form?
Damage to endothelium, cancer, infection -> activation of platelets, turning them into sticky platelets and aggregate in endothelium, becoming foundation on which a thrombus can be formed on
What is the cause of white thrombus in arterial system?
Usually rupture atherosclerotic plaques in arteries and L side of heart
What conditions can arise form arterial thrombosis?
ACS
Ischaemic stroke
Limb claudication / ischaemia
What conditions can arise from venous thrombosis?
DVT
Pulmonary embolism
What is the cause of red thrombus formation in the venous system?
Virchow’s triad and results in back pressure
What are the 3 factors in Virchow’s triad?
Changes to vessel wall (damage)
Changes to blood constituents (hypercoagulability)
Pattern of blood flow (stasis)
What can cause stasis of the blood?
Immobility
Long haul flights
What can cause hypercoagulability?
Inherited Pregnancy Cancer Recent trauma/surgery Sepsis
What can cause endothelial dysfunction?
Hypertension
Smoking
High cholesterol
What can cause endothelial damage?
Catheters
Trauma
Surgery
Define embolism
Intravascular material that migrates from its original location to a distal vessel (thrombus, fat, air, tumour)
Define thromboembolism
Movement of a thrombus along a vessel
What are 2 examples of venous thromboembolism?
Deep vein thrombosis (DVT) Pulmonary embolism (PE)
Visceral VT
Intracranial VT
What are the symptoms of DVT?
Unilateral limb swelling
Persisting discomfort
Calf tenderness
Warmth
Erythema (redness)
Prominent collateral veins
Pitting oedema
May be clinically silent
What can long-term DVT cause?
Post-thrombotic syndrome - damage to venous valves
What are the symptoms of post-thrombotic syndrome?
Swelling
Discomfort
Pigmentation
Ulceration if severe
How is DVT diagnosed?
Clinical assessment and pretest possibility score (wells score)
Blood test: D-dimer if low pre-test score
Imaging: Compression ultrasound - if high pretest score or positive D-dimer
What is D-Dimer?
Breakdown product of cross-linked fibrin
What are the symptoms of PE?
Pleuritic chest pain
Dyspnoea
Haemoptysis
What are the signs of PE?
Pleural rub on auscultation (due to pul. infarction)
What are the signs of a massive PE?
Acute severe dyspnoea Collapse Cyanosis Tachycardia Hypotension Elevated JVP Sudden death
How is PE diagnosed?
Clinical assessment and pretest probability (Wells and Geneva score)
Blood test: d-dimer if low test probability
Imaging: V/Q scan or CT pul. angiogram - if D-dimer positive or pretest high
What can prolonged PE cause?
Most fully recover
Pulmonary arterial hypertension
What are the aims of treatment of VTE?
Prevent clot extension
Prevent clot embolisation
Prevent recurrent clot
What is main treatment of VTE?
Anticoagulation
Parental: unfractionated or LMW heparin
Enteral: warfarin, direct oral anticoagulants (DOAC)
What treatment is given for massive PE?
Thrombolysis (alteplase)
What lines of prevention are taken for PE in hospital?
Early mobilisation
Anti-embolism stockings
Thromboprophylaxis - mechanical and pharmacological
How does pulmonary infarction develop from a PE?
Blockage of branch of pulmonary artery = increase pulmonary pressure
Force in branch too weak to dislodge
Leakage of blood into alveolar spaces -> infarction
