16 - Venous Thromboembolism

Question 1

Where do the majority of DVT originate from

Answer 1

calf venous sinuses

Question 2

Is PE common

Answer 2

3rd most common cause of CV death

Question 3

What are the causes of DVT

Answer 3

Virchow’s triad

• Reduced blood flow – stasis
• Vessel wall disorder
• Hypercoagulability

Question 4

What percentage of DVT are heritable, acquired and idiopathi

Answer 4

Heritable – 25%
Acquired – 50%
Idiopathic – 40%

Question 5

What are some genetic risk factors for DVT

Answer 5

Antithrombin deficiency
Protein C, S deficiency
Factor V Leiden
Prothrombin gene mutation

Question 6

Strong risk factors for DVT

Answer 6

Hip/pelvis fracture
Hip or knee replacement surgery
Trauma

Question 7

Moderate risk factors

Answer 7

Pregnancy
Cancer
Combined OC picc

Question 8

Weak risk factors

Answer 8

Bed rest > 3 days
Obesity
Varicose veins

Question 9

Presentation of DVT

Answer 9

Pain
Swelling
Warmth
Oedema 
(usually unilateral)

Question 10

Why is objective diagnosis important in VTE

Answer 10

Drugs used to treat VTE cause serious side effects

Question 11

Differential diagnosis

Answer 11

Post thrombotic syndrome
Cellulitis
Lymphoedema
Congestive heart failure

Question 12

How do you diagnose DVT

Answer 12

1) Clinical pre test probability
2) D dimer test
3) Radiological assessment - Compression ultrasound, Venography (Gold standard)

Question 13

What is the D-dimer test

Answer 13

blood test for non-specific marker of fibrin formation (usually raised in VTE but also in cancer, infection, inflammation, post-op, pregnancy)

Question 14

What is post-thrombotic syndrome

Answer 14

Recurrent pain and swelling in the leg

more common with proximal DVT

Question 15

What is the cause of post-thrombotic syndrome

Answer 15

Venous hypertension (obstruction and valve damage)
Abnormal microcirculation with reversal of blood flow from deep to superficial veins

Question 16

What are some signs and symptoms of a pulmonary embolism

Answer 16

Breathlessness
Pleuritic chest pain
Tachypnoea and tachycardia
Crepitations and pleural rub

Question 17

What preliminary examinations would you carry out in a PE

Answer 17

ECG - sinus tachycardia,S1Q3T3 pattern
CRX - often normal, may see peripheral wedge shaped density above diaphragm
Arterial Blood Gas

All these can rule out other conditions

Question 18

What is the differential diagnosis for PE

Answer 18

Pneumonia
Asthma
Pneumothorax
Lung Cancer
COPD

Question 19

What are the diagnostic tests for PE

Answer 19

Pulmonary Angiogram - Gold standard
D-dimer
pre-test probability (wells)
Isotope lung scan

Question 20

Prognosis of PE

Answer 20

If treated the prognosis is a lot better and mortality risk reduced to <5%

Question 21

What is the acute treatment of DVT and PE

Answer 21

IV heparin
SQ LMWH
SQ Fondaparinux

Question 22

What is the short term treatment of DVT and PE

Answer 22

Warfarin

SQ LMWH

Question 23

What is the long term treatment of DVT and PE

Answer 23

Warfarin
LQ LMWH
ASA (Aspirin)

Question 24

What blood tests would you ask for a patient with suspected DVT/P

Answer 24

FBC, clotting screen (PT and APTT), D-dimer, U&Es/LFTs

Question 25

Why is LMWH used instead of UFH

Answer 25

LMWH - SQ administration, 4hour half life, Fixed dose, no monitoring needed UFH - IV administration, 60-90min half life, have to monitor with APTT, Variable adjusted dose

Question 26

What is the difference between the use of heparin and warfarin

Answer 26

Heparin is faster acting so would first use heparin for minimum of 5 days with warfarin as it takes a few days for warfarin to start working

Question 27

What is the therapeutic range for the INR

Answer 27

2.0-3.0

Question 28

What is Fondaparinux

Answer 28

Synthetic pentasaccharide An anticoagulant that inhibits factor X Has a 18 hour half life

Question 29

What drugs work on factor Xa

Answer 29

Apixaban Endoxaban Rivaroxaban

Question 30

How does heparin work

Answer 30

Activates antithrombin so thrombin is inactivated

Question 31

How does warfarin work

Answer 31

VitaminK antagonist | Prevents clotting factors 2, 7, 9 and 10, as well as the regulatory factors protein C, protein S, and protein Z.

Question 32

What is the half life of warfarin

Answer 32

36 hours

Question 33

What are the risk of warfarin

Answer 33

Has teratogenicity so not given to pregnant women as a risk to fetus Major bleeding

Question 34

What can you use if you need to reverse the effects of warfarin

Answer 34

Prothrombin complex concentrate - contains the missing clotting factors

Question 35

What are some side effects of heparin

Answer 35

Major bleeding Heparin induced thrombocytopenia Osteoporosis

Question 36

Eg of a heparin antagonist

Answer 36

Protamine sulphate

Question 37

What do you give to a pregnant woman with VTE

Answer 37

LMWH | AVOID WARFAIN AND DOAC as they cross the placenta

Question 38

What do you give to a breastfeeding woman with VTE

Answer 38

LMWH and Warfarin are fine | but not DOACs

Question 39

What do you give to a patient with cancer associated thrombosis

Answer 39

LMWH (more effective than warfarin) | DOAC - under evaluation

Question 40

What is the risk of recurrence of VTE after stopping anticoagulants

Answer 40

Depends on reason for initial event Overall initially 5% risk in 1 year 30% by 10 years = If provoked by transient risk factor – 1-4% in 1st year = If unprovoked or persisting cause – 5-10+% in 1st year

Question 41

When are thrombolytics used and what do they do

Answer 41

Clot busting | used in massive PE or limb threatening DVT

Question 42

When is a inferior vena cava filter used

Answer 42

if major contra-indication to anticoagulation or if recurrence of PE despite adequate anticoagulation

Question 43

What are the percentages of thrombophilia due to - ``` Factor V Leiden Prothrombin gene mutation Protein C deficiency Protein S deficiency Antithrombin deficiency ```

Answer 43

``` Factor V Leiden - 15% Prothrombin gene mutation - 5% Protein C deficiency - 1-2% Protein S deficiency - 1-2% Antithrombin deficiency - <1% ```

Question 44

What does protein C do

Answer 44

inactivates factors Va and VIIIa

Question 45

What does protein S do

Answer 45

Cofactor for Va and VIIIa inactivation by protein C

Question 46

What is antiphospholipid syndrome

Answer 46

Acquired form of thrombophilia Diagnosed with thrombosis and pregnancy morbidity AND lab criteria (Lupus anticoagulant, anticardiolipin antibodies, anti-b2glycoprotein 1 antibodies)