DVT and Pulmonary Embolism Flashcards
What is a thrombus made up of?
Fibrin, platelets and RBCs
Describe the process of thrombosis formation
Damage to endothelial - tissue factor - factor 10 converts prothrombin to thrombin - thrombin converts fibrinogen to fibrin
What are 3 things that can cause thrombosis formation?
Hypercoagulability
Endothelial damage
Stasis
Describe an arterial thrombosis
Usually rupture of atherosclerosis plaque in arteries or left heart chambers
Results in ischaemia and infarction
Diseases include acute coronary syndrome, ischaemic stroke and limb claudication
White thrombus
Explain venous thrombosis
Virchow’s triad - esp. stasis and hypercoagulability in venous valves and venous sinusoids of muscles
Results in back pressure
DVT and PE
Red thrombus
What can cause stasis of blood?
Immobility and long haul travel
What can cause vessel damage?
Endothelial dysfunction - hypertension, smoking and high cholesterol
Endothelial damage - indwelling venous catheters, trauma and surgery
What can cause hypercoagulability of blood?
Can be inherited
Acquired - pregnancy, cancer and sepsis
Explain a DVT
Deep veins have valves and these become incompetent causing stasis of blood
Can be caused from infection or IDU
Causes pain and possible ischaemia
Worried about embolism
What are some examples of venous thromboembolism?
Limb deep vein thrombosis (DVT)
Pulmonary embolism (PE)
Visceral venous thrombosis
Intracranial venous thrombosis
Describe the epidemiology of thromoembolism?
Leading cause of direct maternal death in the UK
1/3 of patients with PE die if left untreated
What are some risk factors for VTE?
Surgery, obstetrics, lower limb problems, malignancy, reduced mobility, miscellaneous
Minor risk factors are cardiovascular and oestrogens
What is used for prevention of VTE in hospitals?
Early mobilisation
Anti-embolism stockings
Other mechanical methods of thromboprophylaxis and pharmacological thromboprophylaxis ex. heparins
What are the symptoms and signs of DVT?
Unilateral limb swelling, persisting discomfort and calf tenderness
Warmth, redness, dilated collateral veins and unilateral pitting oedema
May be clinically silent
How do you diagnose a DVT?
Clinical assessment and pre-test probability score (wells score)
Blood test - D-dimmer
Imaging - compression US if positive D-dimer or high pre-test
Describe the Wells score for DVT
9 factors contributing
if < or equal to 1 then 1/10 chance of DVT then d-dimer
If >2 or equal to then 1/3 chance of DVT, gold standard test done - US
Explain what a D-dimer is
Breakdown product of cross-linked fibrin produced during fibrinolysis
High sensitivity and low specificity for VTE As other factors can cause activation of clotting cascade
What are the symptoms and signs of PE?
Pleuritic chest pain, breathlessness, possible blood in sputum, tachycardia and pleural rub on auscultation usually due to pulmonary infarct
What are the signs and symptoms of a massive pulmonary embolism?
Severe dyspnoea of sudden onset, collapse, blue lips and tongue, tachycardia, low blood pressure and raised JVP
May also cause sudden death
Describe the Wells score for PE
If < or equal to 4 then low risk so D-dimer blood test
If > 4.5 then high risk so ventilation/ perfusion scan or CT pulmonary angiogram
How is PE diagnosed?
Clinical assessment and pre-test probability score
Blood test - d-dimer if low pre-test
Imaging - if D-dimer positive or pre-test probability score. Isotope V/Q scan or CT pulmonary angiogram
What are some questions to ask in a patient with diagnosed VTE?
Recent surgery or hospitalisation
Any symptoms or signs to suggest underlying malignancy - urine and blood tests then CXR
Consider risk of recurrence
What are the treatment options for PE?
Anticoagulation is main treatment
Can be parental options or enteral options
Direct oral anticoagulants used the most
What are the parental options of treatment?
Low molecular weight heparin - factor 10A inhibitor, no monitoring and first choice in patients with malignancy
Unfractionated heparin - inhibitor of intrinsic pathway and given by IV so needs close monitoring
What are the enteral options of treatment?
Direct oral anticoagulants - 10A inhibitors or direct thrombin inhibitors, no monitoring
Warfarin - inhibitor of Vit K dependant clotting factors, needs close monitoring as can cause renal failure
What is the treatment for massive DVTs and PE?
Vascular surgery intervention in massive DVTs
Thrombolysis reserved for massive PE - Alteplase
What are the aims of treatment for VTE?
Prevent clot extension
Prevent clot embolization
Prevent clot recurrence
What are the potential long-term consequences of DVT?
Post thrombotic syndrome - damage to venous valves
Swelling, discomfort, pigmentation and ulceration
What are the potential long-term consequences of pulmonary embolism?
Most recover fully
Pulmonary arterial hypertension which is serious
