Venous Thromboembolism

Question 1

What is a thrombosis?

Answer 1

pathological clot (thrombus) formation within a blood vessel.

Question 2

What is an embolism?

Answer 2

clot which breaks off and travels through circulation until it gets obstructed by a smaller vessel

Question 3

What do venous thrombi look like?

Answer 3

Red clots

Question 4

What do arterial thrombi look like?

Answer 4

White clots

Question 5

What are the main examples of venous thromboembolism (VTE)

Answer 5

DVT - deep vein thrombosis
Pulmonary embolism
Venous thrombosis at other sites such as axillary vein
Other causes of embolism - fat, amniotic fluid

Question 6

Where can you get a DVT?

Answer 6

Distal - confined to calf veins

Proximal - involve popliteal vein or above

Question 7

What are the 3 causes of VTE?

Answer 7

Reduced blood flow (stasis)
vessel wall disorder
hypercoagulability

Question 8

How does someone get VTE? (3 ways)

Answer 8

heritable - 25%
acquired - 50%
idiopathic - 40%
many inherited and acquired

Question 9

What are some genetic RF for VTE?

Answer 9

Factor V leiden
Protein C and S deficiency
Antithrombin deficiency
Elevated factor VIII, IX, XI

Question 10

What are some strong acquired RF for VTE?

Answer 10

Hip/pelvis fracture
hip/knee replacement
major trauma
spinal cord injury

Question 11

What are some moderate RF for VTE?

Answer 11

Previous VTE
cancer
respiratory failure
pregnancy
HRT
central veous line
thrombophilia

Question 12

What are some weak RF for VTE?

Answer 12

bed rest > 3 days
travel related thrombosis
obesity
varicose veins

Question 13

How does DVT present itself?

Answer 13

Unilateral
swelling
warmth
ipsilateral oedema
superficial venous dilation
palpable cord which is the thrombosed vein
tenderness
pain

Question 14

Why is objective diagnosis for VTE so important?

Answer 14

Over 75% patients with suspected VTE are negative on inspection
Drugs to treat have serious side effects

Question 15

What are some examples of differential diagnoses?

Answer 15

ruptured Baker's cyst (popliteal)
cellulitis
compression of iliac veins
musculo-tendinous trauma
lymphoedema

Question 16

How do you diagnose DVT?

Answer 16

In this order:

• Clinical pre test probability where give a score based on presentation features and history (likelihood)
• D-dimer levels check as usually raised in VTE but also pregnancy, infection, inflammation
• Radiological assessment - compression ultrasound non invasive, venography is looking for calf DVT, CT

Question 17

What are some complications of DVT?

Answer 17

pulmonary embolism
extension of clot
post-thrombotic syndrome (recurrent pain and swelling, venous hypertension)

Question 18

How does a pulmonary embolism present?

Answer 18

tachycardia and tachypnoea
isolated breathlessness
hypotension shock
pleuritic chest pain
hypoxia
CXR normal, maybe pleural effusion
often non-diagnostic

Question 19

What are some differential diagnoses for pulmonary embolism?

Answer 19

Pneumonia/bronchitis
asthma
anxiety
acute coronary syndrome
pneumothorax
lung cancer
pericardial tamponade

Question 20

How do you diagnose pulmonary embolism?

Answer 20

CT pulmonary angiogram
isotope lung scan
chest x ray
echocardiogram
pulmonary angiogram
leg ultrasound
D-dimer

Question 21

What is the traditional basic treatment for DVT and PE?

Answer 21

Do blood tests and start heparin unless there is a contraindication (usually LMWH), confirm diagnosis with 24hrs and if confirmed continue heparin and start warfarin, stop heparin after 5 days min. when INR is in therapeutic range and continue warfarin while monitoring, review at 3 months

Question 22

What is LMWH?

Answer 22

Low molecular weight heparin
Safer than UFH
more predictable anticoagulant response
no monitoring needed so easier
subcutaneous admin

Question 23

What is UFH?

Answer 23

Unfractionated heparin
IV admin
monitor by APTT
used where rapid reversibility is important as has short half life

Question 24

What site does heparin work on?

Answer 24

Factor Xa and thrombin

Question 25

What are the side effects of heparin?

Answer 25

major bleeding
heparin induced thrombocytopenia - discontinue it and replace anticoagulant
osteoporosis

Question 26

What is warfarin?

Answer 26

Vitamin K antagonist
oral admin
delayed onset of action
Affects PT
risk to fetus

Question 27

What site of action does warfarin have?

Answer 27

Factor X, II, IX

Question 28

What to do if need rapid reversal of warfarin as too much bleeding?

Answer 28

PCC - prothrombin complex concentrate which contains missing clotting factors

Question 29

What are the main 3 drug treatment options?

Answer 29

• LMWH bridged to warfarin
• LMWH followed after 5 days by dabigatran or edoxaban
• rivaroxaban or apixaban alone
  (an’s are all DOACs, direct oral anticoagulants)

Question 30

For which groups of people may treatment be different ?

Answer 30

Pregnant
Breastfeeding
Patients with cancer associated thrombosis

Question 31

Why would treatment be different for pregnant women and what do you do?

Answer 31

Warfarin and DOACs cross placenta so teratogenic/increase bleeding risk
So use LMWH throughout

Question 32

Why would treatment be different for those breastfeeding?

Answer 32

DOACs not safe

Question 33

What would you do in regards to treatment for patients with cancer-associated thrombosis?

Answer 33

LMWH more effective than warfarin

Question 34

What are some other interventions for VT apart from drugs?

Answer 34

Thrombolysis - used in massive/life threatening PE and DVT, small risk of intracranial bleeding
IVC filter
graduated compression stockings

Question 35

What is antiphospholipid syndrome?

Answer 35

Autoimmune hypercoagulable state caused by antiphospholipid antibodies, can cause thrombosis and/or pregnancy morbidities

Question 36

Out of heparin and warfarin which is LT and which is ST?

Answer 36

heparin ST

warfarin LT