Venous Thromboembolism

Question 1

What are the three components of Virchow’s Triad

Answer 1

• Abnormal blood flow - stasis
• Hypercoagulability
• Vascular Injury

Question 2

Which factors of the coagulation cascade are important in the generation of thrombin

Answer 2

Factors 5 and 8

Question 3

What does tissue damage lead to the release of

Answer 3

Tissue factor

Question 4

What two factors combine to form factor 10a

Answer 4

Factors 7a and tissue factor

Question 5

What is kind of membrane is required for the clotting cascade to occur

Answer 5

A phospholipid membrane in the form of platelets or monocytes.

Question 6

What does the tissue factor pathway inhibitor do

Answer 6

Prevents the generation of factor 10a.

Question 7

What is post thrombotic syndrome

Answer 7

A permanent pain and swelling.

Question 8

What are the risk factors for venous thromboembolism

Answer 8

• Age
• Obesity
• Varicose veins
• Previous VTE
• Thombophilia
• Cancer
• Other thrombotic states
• Hormone therapy
• Pregnancy
• Immobility
• Hospitalisation
• Anaesthesia
• Central venous catheters.

Question 9

What is the issue with diagnosis of VTE

Answer 9

80% of DVT are clinically silent.

Question 10

What are the clinical symptoms of DVT

Answer 10

• Pain
• Swelling
• Increased temperature of the limb
• Dilatation of superficial veins

Question 11

Is DVT usually unilateral or bilateral

Answer 11

Unilateral

Question 12

When may a DVT be bilateral

Answer 12

If thrombosis is sited in the inferior vena cava

Question 13

What are the differential diagnosis of DVT

Answer 13

Calf haematoma, ruptured Baker’s cyst, cellulitis

Question 14

What is Well’s score used for

Answer 14

To predict which patients might have DVT. Patients are put into low, moderate and high risk categories depending on the score.

Question 15

What investigations are used to diagnose DVT

Answer 15

• Contrast venography
• Venous ultrasoundography
• D-dimer test

Question 16

What are the diagnostic results of DVT in venous ultrasoundography

Answer 16

Non-compressibility of the common femoral vein or popliteal vein.

Question 17

What are the clinical features of pulmonary embolism

Answer 17

• Collapse, faintness, crushing central chest pain
• Pleuritic chest pain
• Difficulty breathing
• Haemoptysis
• Extertional dyspnoea

Question 18

What is pleuritic chest pain

Answer 18

Pain in the chest which worsens when breathing in

Question 19

What is haemoptysis

Answer 19

Coughing up blood

Question 20

What investigations are used in the diagnosis of PE

Answer 20

• Chest x-ray
• Electrocardiogram
• Arterial blood gases
• D-dimer
• Ventilation perfusion scan
• CT angiogram
• Echocardiogram

Question 21

Why is a chest x-ray used in the diagnosis of PE

Answer 21

To rule out other possible diagnosis

Question 22

What will be shown on an echocardiogram in someone with a pulmonary embolism

Answer 22

On an echocardiogram, a high right sided ventricular pressure will be shown due to resistance from the pulmonary circulation as a result of the PE.

Question 23

What are the principles of anticoagulant therapy

Answer 23

Rapid initial anticoagulation followed by extended therapy.

Question 24

What can be given for rapid initial anticoagulation

Answer 24

Parenteral anticoagulant or direct oral anticoagulant

Question 25

What are examples of parenteral anticoagulants

Answer 25

- Heparin - Low molecular weight heparin - Fondaparinux

Question 26

When are direct oral anticoagulants used

Answer 26

In emergency situations.

Question 27

Why are direct oral anticoagulants only used in emergency situations

Answer 27

Because it takes 4 hours for absorption so if a person has collapsed due to PE, they will be given parenteral heparin as this ensures absorption and brings about a response more quickly.

Question 28

What can be given for extended therapy after a PE

Answer 28

An orally active anticoagulant or a direct anticoagulant.

Question 29

What is an example of an orally active anticoagulant

Answer 29

A vitamin K antagonist such as warfarin.

Question 30

What is the aim of extended anticoagulant therapy

Answer 30

To prevent recurrent thrombosis and chronic complications such as post phlebitic syndrome

Question 31

What are DOACs

Answer 31

Direct oral anticoagulants

Question 32

What are four examples of DOACs

Answer 32

Dabigatran, Rivaroxaban, Edoxaban and apixaban

Question 33

What does dabigatran do

Answer 33

Dabigatran inhibits the action of thrombin in the formation of a thrombus

Question 34

What do rivaroxaban, edoxaban and apixaban

Answer 34

Rivaroxaban, edoxaban and apixaban inhibit factor 10a to prevent the progression of the clotting cascade

Question 35

Which two points are important in the clotting cascade and therefore are drug targets

Answer 35

The formation of factor 10a and thrombin action to convert fibrinogen into fibrin.

Question 36

What is sometimes given alongside DOACs

Answer 36

Heparin

Question 37

What is the action of DOACs

Answer 37

They enable rapid initial anticoagulation orally and then are given at a lower dose for secondary prevention of venothromboembolism.

Question 38

Which DOACs do not need to be given alongside heparin

Answer 38

Apixaban and rivaroxaban

Question 39

What investigations are used to investigate a procoagulant tendency

Answer 39

- Full blood count - Antithrombin - Protien C - Protein S - Thrombin time

Question 40

In what situation is the DOAC argatroban used

Answer 40

Where the person is allergic to heparin.

Question 41

What factors are thrombin and prothrombin

Answer 41

Thrombin is factor IIa and prothrombin is factor II.

Question 42

What are two types of heparin

Answer 42

Unfractionated and low-molecular weight heparin.

Question 43

Which type of heparin is more bioavailable

Answer 43

Low molecular weight heparin

Question 44

How does heparin work

Answer 44

It binds to pentasaccharide on antithrombin and brings about its inhibitory action towards factor Xa and thrombin.

Question 45

What's negative about prescribing unfractionated heparin

Answer 45

It has an unpredictable anticoagulant response due to binding to plasma proteins so requires monitoring using APTT.

Question 46

What conditions could develop due to unfractionated heparin

Answer 46

Osteoporosis and heparin-induced thrombocytopenia

Question 47

What is there a high risk of with unfractionated heparin

Answer 47

Bleeding.

Question 48

What are the two positives about the use of low molecular weight heparin

Answer 48

It has almost 100% bioavailability and no monitoring is required.

Question 49

What is the negative about the use of low molecular weight heparin

Answer 49

It is not reversible

Question 50

What are coumarins

Answer 50

They inhibit vitamin K dependent carboxylation of factors 2, 7, 9 and 10

Question 51

What is the most common coumarin

Answer 51

Vitamin K

Question 52

By what method are coumarins such as warfarin taken

Answer 52

Orally

Question 53

How are coumarins such as warfarin monitored

Answer 53

By the international normalised ratio (INR) derived from the prothrombin time (PT)

Question 54

How can the effect of warfarin be reversed

Answer 54

Dietary intake of vitamin K, fresh frozen plasma and concentrates of the factors inhibited by warfarin.

Question 55

What are the negative aspects of prescribing warfarin

Answer 55

There are many drug interactions with warfarin and requires monitoring at least monthly.

Question 56

What is the negative aspect about using DOACs instead of warfarin

Answer 56

Their effect cannot really be revered.

Question 57

Which is currently the only DOAC that can be reversed

Answer 57

Dabigatran. The factor 10a inhibitors cannot yet be reversed.