Deep Vein Thrombosis & Pulmonary Embolism

Question 1

What are the three components of Virchow’s triad?

Answer 1

Hypercoagulability
Endothelial injury
Venous stasis

Question 2

What are potential reasons for an individual having a hypercoagulable state?

Answer 2

Malignancy
Pregnancy (even in the peripartum)
Oestrogen therapy
IBD
Sepsis
Thrombophillia

Question 3

What are potential causes of endothelial injury?

Answer 3

Smoking
Venous disorders
Venous valvular disorders
Trauma/Surgery
Indwelling catheters

Question 4

What are causes of circulatory stasis?

Answer 4

Left ventricular dysfunction
Immobility or paralysis
Venous insufficiency/Varicose veins
Venous obstruction (e.g. tumor, obesity, pregnancy)

Question 5

Which veins are commonly involved in DVTs?

Answer 5

Calves

Those affecting the popliteal vein and femoral vein are more likely to embolise.

Question 6

How is DVT diagnosed?

Answer 6

D-dimer (if low-risk)
US Doppler of leg is diagnostic - perform if clinical suspicion exists

Question 7

How is DVT managed in the acute presentation?

Answer 7

Anticoagulate - apixaban and rivaroxaban (or other DOACs) are first line.

If patient cannot take these, give LMWH followed by dabigatran/edoxaban. May also give LMWH followed by warfarin.

Question 8

What are secondary treatments used to prevent DVT in the long-term?

Answer 8

Can give either:
Warfarin
LMWH
DOACs

Question 9

How long should anticoagulant therapy be continued in those with a provoked DVT, accompanied by reversible risk factors?

Answer 9

Continue for 3 months.

Question 10

How long should anticoagulant therapy be continued in those with a provoked DVT, accompanied by irreversible factors/an unprovoked DVT?

Answer 10

Atleast 3-6 months - may need life-long if patient has serious risk factors (e.g. clotting disorder).

Question 11

What is the most common pre-cursor of a pulmonary embolism?

Answer 11

DVT - occurs in 95% of cases.

May also result from AF.

Question 12

How can AF cause a PE?

Answer 12

Blood clots form within the atria due to stasis of blood, which then embolises to the pulmonary arteries.

Question 13

What scoring system is used to determine potential risk of a PE?

Answer 13

Wells score

Question 14

If Wells score suggests potential PE, what is performed?

Answer 14

CT-pa

This is gold standard in the diagnosis of a PE.

Question 15

If Wells scores suggests a PE is unlikely, what is performed?

Answer 15

D-dimer

If this is positive, carry out CT-pa.

Question 16

In which patients may a V/Q scan be used rather than CT-pa?

Answer 16

Renal impairment
Contrast allergy
Pregnancy (although if v unwell, peform CT-pa)

Question 17

How does PE appear on an ABG?

Answer 17

Type 1 respiratory failure, with respiratory alkalosis.

Question 18

How is PE treated acutely?

Answer 18

DOACs are first-line.

Thrombolysis is indicated if massive PE and circulatory failure exists (i.e. hypotension).