Venous Thrombosis and Pulmonary Embolism

Question 1

What is a thrombus?

Answer 1

A solid mass of blood components formed in an artery or vein during life

Question 2

Where do venous thrombi tend to form?

Answer 2

Most often at the valves of the deep veins of the legs - can propagate up or down from there

Question 3

What factors predispose to venous thrombosis?

Answer 3

Changes in the vessel wall
Changes in the constituents of the blood
Changes in the blood flow

Question 4

What are primary hypercoagulable states?

Answer 4

Genetic predispositions 
Common:
- factor V Leiden - prevents APC from binding to cleavage site
- prothrombin III deficiency 
Uncommon:
- antithrombin III deficiency 
- protein C or protein S deficiency

Question 5

What are secondary hypercoagulable states?

Answer 5

Acquired states eg:
- surgery, massive trauma and burns, malignancy, obesity, smoking, hyper-oestrogenic states, nephrotic syndrome, anti-phospholipid antibody syndrome

Question 6

What are the 4 fates of a thrombus?

Answer 6

1) lysis –> flow is restored
2) undergo organisation –> scar formed on vessel wall
3) recanalisation –> new blood vessels sprout from vessel wall into thrombus and establish new vascular channels –> restore flow
4) embolism –> carried to a different site, can cause infarction or other clinical problems

Question 7

What is an embolus?

Answer 7

A mobile mass of material within the vascular system able to lodge within a vessel, occlude its lumen and obstruct its blood flow

Question 8

What is pulmonary thromboembolism?

Answer 8

Most arise from DVT, which travels to the right side of the heart and enters the pulmonary arterial circulation via the pulmonary artery

Question 9

What are the clinical effects of a pulmonary embolus?

Answer 9

Sudden death, dyspnoea, chest pain and circulatory failure mimicking myocardial infarction

Question 10

What are the clinical effects of a pulmonary embolus in the R or L pulmonary artery?

Answer 10

Sudden death, dyspnoea, chest pain and circulatory failure mimicking myocardial infarction

Question 11

What are the clinical effects of a small pulmonary embolus?

Answer 11

Pulmonary infarct 
- wedge shaped
- red (dual blood supply) 
- sharply demarcated
Clinically 
- dyspnoea, pleuritic chest pain, haemoptysis