DVT and Pulmonary Embolism

Question 1

What is a thrombus made up of?

Answer 1

Fibrin, platelets and RBCs

Question 2

Describe the process of thrombosis formation

Answer 2

Damage to endothelial - tissue factor - factor 10 converts prothrombin to thrombin - thrombin converts fibrinogen to fibrin

Question 3

What are 3 things that can cause thrombosis formation?

Answer 3

Hypercoagulability
Endothelial damage
Stasis

Question 4

Describe an arterial thrombosis

Answer 4

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

Question 5

Explain venous thrombosis

Answer 5

Virchow’s triad - esp. stasis and hypercoagulability in venous valves and venous sinusoids of muscles
Results in back pressure
DVT and PE
Red thrombus

Question 6

What can cause stasis of blood?

Answer 6

Immobility and long haul travel

Question 7

What can cause vessel damage?

Answer 7

Endothelial dysfunction - hypertension, smoking and high cholesterol
Endothelial damage - indwelling venous catheters, trauma and surgery

Question 8

What can cause hypercoagulability of blood?

Answer 8

Can be inherited
Acquired - pregnancy, cancer and sepsis

Question 9

Explain a DVT

Answer 9

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

Question 10

What are some examples of venous thromboembolism?

Answer 10

Limb deep vein thrombosis (DVT)
Pulmonary embolism (PE)
Visceral venous thrombosis
Intracranial venous thrombosis

Question 11

Describe the epidemiology of thromoembolism?

Answer 11

Leading cause of direct maternal death in the UK
1/3 of patients with PE die if left untreated

Question 12

What are some risk factors for VTE?

Answer 12

Surgery, obstetrics, lower limb problems, malignancy, reduced mobility, miscellaneous
Minor risk factors are cardiovascular and oestrogens

Question 13

What is used for prevention of VTE in hospitals?

Answer 13

Early mobilisation
Anti-embolism stockings
Other mechanical methods of thromboprophylaxis and pharmacological thromboprophylaxis ex. heparins

Question 14

What are the symptoms and signs of DVT?

Answer 14

Unilateral limb swelling, persisting discomfort and calf tenderness
Warmth, redness, dilated collateral veins and unilateral pitting oedema
May be clinically silent

Question 15

How do you diagnose a DVT?

Answer 15

Clinical assessment and pre-test probability score (wells score)
Blood test - D-dimmer
Imaging - compression US if positive D-dimer or high pre-test

Question 16

Describe the Wells score for DVT

Answer 16

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

Question 17

Explain what a D-dimer is

Answer 17

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

Question 18

What are the symptoms and signs of PE?

Answer 18

Pleuritic chest pain, breathlessness, possible blood in sputum, tachycardia and pleural rub on auscultation usually due to pulmonary infarct

Question 19

What are the signs and symptoms of a massive pulmonary embolism?

Answer 19

Severe dyspnoea of sudden onset, collapse, blue lips and tongue, tachycardia, low blood pressure and raised JVP
May also cause sudden death

Question 20

Describe the Wells score for PE

Answer 20

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

Question 21

How is PE diagnosed?

Answer 21

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

Question 22

What are some questions to ask in a patient with diagnosed VTE?

Answer 22

Recent surgery or hospitalisation
Any symptoms or signs to suggest underlying malignancy - urine and blood tests then CXR
Consider risk of recurrence

Question 23

What are the treatment options for PE?

Answer 23

Anticoagulation is main treatment
Can be parental options or enteral options
Direct oral anticoagulants used the most

Question 24

What are the parental options of treatment?

Answer 24

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

Question 25

What are the enteral options of treatment?

Answer 25

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

Question 26

What is the treatment for massive DVTs and PE?

Answer 26

Vascular surgery intervention in massive DVTs
Thrombolysis reserved for massive PE - Alteplase

Question 27

What are the aims of treatment for VTE?

Answer 27

Prevent clot extension
Prevent clot embolization
Prevent clot recurrence

Question 28

What are the potential long-term consequences of DVT?

Answer 28

Post thrombotic syndrome - damage to venous valves
Swelling, discomfort, pigmentation and ulceration

Question 29

What are the potential long-term consequences of pulmonary embolism?

Answer 29

Most recover fully
Pulmonary arterial hypertension which is serious