Deep vein thrombosis and thromboembolism - presentation, investigation and therapy

Question 1

what is a ‘clot’ made up of

Answer 1

fibrin platelets red blood cells

Question 2

describe the process of thrombosis

Answer 2

damage to endothelium tissue factor exposure prothrombin converted into thrombin thrombin turns fibrinogen into fibrin cross-linked fibrin

or damage to endothelium - exposure of collagen - platelet adhesion and release - platelet recruitment and activation platelet aggregation platelet-fibrin thrombus

Question 3

arterial thrombosis:- - mechanism - location of origin - results in - diseases - composition

Answer 3

usually rupture of atherosclerotic plaque in arteries, left heart chambers ischaemia and infarction as a result diseases:-

• Acute coronary syndrome
• Ischaemic stroke
• Limb claudication / ischaemia composition - ‘white thrombus’ - platelets and fibrin

Question 4

venous thrombosis:- - mechanism - location of origin - results in - diseases - composition

Answer 4

Combination of Virchow’s triad, especially - stasis and hypercoagulability Venous valves and venous sinusoids of muscles results in back pressure deep vein thrombosis pulmonary embolism ‘red thrombus’ RBCs and fibrin

Question 5

3 categories of Virchow’s triad that are said to cause thrombosis

Answer 5

stasis vessel damage - endothelial damage/dysfunction hypercoagulability - inherited or acquired (pregnancy, cancer or sepsis)

Question 6

things causing endothelial dysfunction

Answer 6

hypertension smoking high cholesterol

Question 7

things causing endothelial damage

Answer 7

indwelling venous catheters trauma surgery

Question 8

examples of venous thromboembolism (4)

Answer 8

Limb deep vein thrombosis (DVT) Pulmonary embolism (PE) Visceral venous thrombosis Intracranial venous thrombosis

Question 9

epidemiology of venous thromboembolism:- DVT and PE

Answer 9

DVT - 1 in 1000 PE - 1 in 3000-5000 leading cause of direct maternal death in UK incidence increases with age and higher in females

Question 10

risk factors for VTE

Answer 10

Surgery:-

• Major abdominal/pelvic surgery
• Hip/knee replacement
• Postoperative intensive care

Obstetrics:-

• Late pregnancy
• C-section

Lower limb problems:-

• Fracture
• Varicose veins

Malignancy:-

• Abdominal/pelvic
• Advanced/metastatic
• Reduced mobility
• Hospitalisation Institutional care

Miscellaneous:- Previous proven VTE

Cardiovascular:-

• Congenital heart disease
• Congestive cardiac failure
• Hypertension
• Superficial venous thrombosis
• Indwelling central vein catheter
• Oral contraceptive
• Hormone replacement therapy
• COPD
• Neurological disability
• Occult malignancy
• Thrombotic disorders
• Long distance sedentary travel
• Obesity

Question 11

symptoms and signs of DVT

Answer 11

Unilateral limb swelling persisting discomfort calf tenderness warmth, redness - erythema, prominant collateral veins, unilateral pitting oedema

Question 12

potential long-term consequences of DVT

Answer 12

Post thrombotic syndrome - damage to venous valves - 20-60% incidence within 2 years of DVT Swelling Discomfort Pigmentation Ulceration in severe form

Question 13

Diagnosis of DVT

Answer 13

Clinical assessment

FBC - D-dimer - positive result may indicate the presence of an abnormally high level of fibrin degradation products

imaging: B mode venous compression ultrasound, doppler, ultrasonography

Question 14

what is a compression ultrasound?

Answer 14

probe put on skin, sound waves are able to construct an image of the tissue that lies beneath

Question 15

wells criteria scoring

Answer 15

> or equal to 3 = high probability of DVT 1 or 2 = moderate probability < or equal to 0 = low probability

Question 16

D- dimer sensitivity and specificity for VTE?

Answer 16

high sensitivity low specificity - trauma, malignancy, sepsis, bleeding, cancer, recent surgery

Question 17

symptoms and signs of PE

Answer 17

Pleuritic chest pain Breathlessness- dyspnoea haemoptysis Rapid heart rate- tachycardia Pleural rub on auscultation usually due to pulmonary infarction

Question 18

Symptoms and signs of massive pulmonary embolism

Answer 18

Severe dyspnoea of sudden onset Collapse Blue lips and tongue - cyanosis Tachycardia Low blood pressure Raised jugular venous pressure May cause sudden death

Question 19

Diagnosis/inestigations for PE

Answer 19

Clinical assessment and pretest probability score (Wells score or Geneva score)

• D-dimer - if negative - no PE
• FBC
• CXR - blunt costophrenic angle
• V/Q scan
• Ultrasound
• CT pulm angiogram/MRI

Question 20

Potential long-term consequence of pulmonary embolism

Answer 20

Most recover fully Pulmonary arterial hypertension

Question 21

aims of treatment of VTE? (DVT or PE) (3)

Answer 21

Prevent clot extension Prevent clot embolisation Prevent recurrent clot

Question 22

treatment options for VTE

Answer 22

Anticoagulation is main treatment Parenteral (not mouth or alimentary canal) options: unfractionated heparin low molecular weight heparin (good for women who are pregnant/child baring age) Enteral options: Warfarin Direct Oral Anticoagulants (DOACs)

Question 23

when is thrombolysis opted for as treatment option?

Answer 23

severe cases like for massive PE Alteplase

Question 24

prevention of VTE in hospital (4)

Answer 24

Early mobilisation ‘Anti-embolism stockings’ Other mechanical methods of thromboprophylaxis Pharmacological thromboprophylaxis

Question 25

how do you develop a pulmonary infarction after a PE

Answer 25

Pulmonary infarction = rare due to dual vascular supply to lungs with anastomoses (linkwith) - Pulmonary vascular system - Bronchial vascular system These circulations supply majority of O2 to lung parenchyma Pre and post capillary anastomoses with pulmonary system Blockage to a branch of the pulmonary artery = increase in pressure within pulmonary vasculature Force within bronchial artery may be insufficient to overcome this ‘Leakage’ of blood into alveolar space occurs, and leads to infarction

Question 26

Diagnostic algorithm for DVT - see image

Answer 26

Question 27

why is low molecular weight heparin the better option over warfarin for DVT

Answer 27

You need to be loaded with warfarin before it has a therapeutic effect therefore it would not be the immediate treatment

LMWH (version of heparin) like daltaparin is a safe option during pregnancy a

Question 28

direct oral anticoagulants have taken the place of which other drugs for treatment of DVT

Answer 28

Direct oral anticoagulants are better option over:-

• warfarin
• LMWH - daltaparin

LMWH is better than warfarin however