Deep vein thrombosis and thromboembolism

Question 1

Define Thrombosis

Answer 1

A solid mass formed IN the circulation from the constituents of the blood during life
(thrmobus is a clot in a BV essentially that results from a complex series of events involving coagulation factors, platelets, red blood cells and vessel wall)

Question 2

What are fragments of thrombi called?

Answer 2

Emboli

Question 3

What is the difference between a thrombus in the arterial and venous circulation

Answer 3

Arterial circulation = High pressure and platelet rich

Venous circulation = Low pressure and fibrin rich

Question 4

What can result from an arterial thrombus in the coronary circulation

Answer 4

Myocardial ischaemia or infarction

Question 5

What can result from an arterial thrombus in the cerebral circulation

Answer 5

Transient Ischaemic Attack (TIA) or Stroke

Question 6

What can result from an arterial thrombus in the peripheral vascular circulation

Answer 6

Peripheral vascular disease (PVD) - claudication, rest pain and gangrene

Question 7

Risk factors of arterial thrombosis

Answer 7

(Similar to that of atherosclerosis)
Smoking
Hypertension
Diabetes
Hyperlipidemia
Obesity/sedentary lifetsyle
Stress

Question 8

Pathophysiology of arterial thrombosis

Answer 8

• Result of an atheroma that forms in areas of turbulent blood flow such as the bifurcation of arteries
• Platelets adhere to the damaged vascular endothelium and aggregate in response to ADP and thromboxane A2
• Plaque rupture leads to the exposure of blood containing factor VIIa to tissue factor within the plaque which may trigger blood coagulation and lead to thrombus formation
• This can result in complete occlusion of the vessel or embolisation that produces distal obstruction

Question 9

Diagnosis of arterial thrombosis

Answer 9

Myocardial infarction
History
Cardiac enzymes
Cerebrovascular accident
Peripheral vascular disease

Question 10

Diagnosis of arterial thrombosis myocardial infarction

Answer 10

STEMI ECG
Diagnosed on presentation
ST elevation
Tall T waves
LBBB
T wave inversion and pathological Q waves follow

Question 11

Diagnosis of arterial thrombosis Cerebrovascular accident

Answer 11

History and examination

CT/MRI scan

Question 12

Diagnosis of arterial thrombosis peripheral vascular disease

Answer 12

History and examination

Ultrasound and angiogram

Question 13

Prevention of arterial thrombosis

Answer 13

• COX inhibitor e.g. ASPIRIN which inhibits platelet aggregation
• P2Y12 inhibitor e.g. CLOPIDOGREL which inhibits ADP from binding to the P2Y12 receptor
• DIPYRAMIDOLE inhibits phosphordiesterase-mediated breakdown of cyclic AMP which prevents platelet activation

Question 14

Prevention (and treatment) of MI from arterial thrombosis

Answer 14

• ASPIRIN - inhibits platelet function as COX inhibitor
• Thrombolytic therapy:
- STREPTOKINASE
- TISSUE PLASMINOGEN ACTIVATOR which generates plasmin and degrades fibrin clot

Question 15

Prevention (and treatment) of stroke from arterial thrombosis

Answer 15

• ASPIRIN or CLOPIDOGREL
• TISSUE PLASMINOGEN ACTIVATOR (for brain attack, only have a narrow window)
• Treat risk factors

Question 16

Clinical presentation of DVT

Answer 16

Often progresses to pulmoary embolism before presenting.
Classical features include:
Limb pain and tenderness along the lines of the deep veins, pain/swelling of the calf, increase in skin temperature, pitting oedema.
Resembles cellulitis

Question 17

Aetiology of DVT

Answer 17

Thrombotic risk factors
Surgery, immobility, leg fracture, oral contraceptive pill
Genetic or acquired causes

Question 18

What is more concerning:

DVT in calf below the knee or above the knee

Answer 18

Above the knee is potentially fatal and occurs in the proximal leg vein.

Question 19

Genetic cause of DVT

Answer 19

Factor V Leiden

PT20210A

Question 20

Acquired causes of DVT

Answer 20

Anti-phospholipid syndrome
Lupus anticoagulant
Hyperhomocysteinaemia

Question 21

Risk factors of DVT

Answer 21

Age (higher)
Pregnancy
Synthetic oestrogen
Trauma
Surgery (especially pelvic or orthopaedic)
Past DVT
Cancer
Obesity
Immobility

Question 22

DVT pathophysiology

Answer 22

Formation of the thrombus in the deep vein.

This can embolise and often flows up into the pulmonary circulation as a pulmonary embolism

Question 23

Diagnosis of DVT

Answer 23

Ultrasound (compression Ultras = find popliteal vein, if can squash it shut then NO DVT and vice versa)
D-dimers (plasma)
Contrast venography

Question 24

What is D-dimer

Answer 24

Type of fibrinogen degradation product that is released into the circulation when a clot begins to dissolve

Question 25

Treatment of DVT

Answer 25

LMW Heparin

other anticoagulation also possible e.g. Oral warfarin

Question 26

Give example of a LMW Heparin

Answer 26

SC Enoxaparin

Question 27

Prevention of DVT

Answer 27

• Early mobilisation after operation
• Compression stockings
• Thrombophylaxis for both low risk and high risk

Question 28

WHat can be used to score risk factors of DVT

Answer 28

WELLS score

Question 29

Risk factors e.g. in WELLS score

Answer 29

Active cancer, bed ridden, calf swelling,

Question 30

NOAC (DOAC same thing) VS Warfarin

Answer 30

NOAC - New oral anticoagulant drugs (INR does not need monitoring); easy to reverse side effects compared to warfarin (vitamin K replacement); shorter half life

Warfarin has more complications

Question 31

Example of Vitamin K supplement

Answer 31

Beriplex (used to reverse effects of excess bleeding)

Question 32

Examples of anticoagulants

Answer 32

Heparin
Warfarin
NOACs

Question 33

Examples of NOACs and what they inhibit

Answer 33

Factor Xa inhibitors: Rivaroxaban, Apixaban
Thrombin inhibitor:
Dabigatran

Question 34

How does warfarin work

Answer 34

Inhibits reductase enzyme responsible for regenerating active form of vitamin K - leads to analogous vitamin K deficiency