venous thromboembolic disease

Question 1

what is a thrombosis

Answer 1

a localised solid mass of blood constituents forms within a vessel, mostly as a result of fibrin formation with a variable contribution from platelets and other cells

Question 2

what are emboli

Answer 2

fragments that can break off of emboli and block a vessel downstream

Question 3

what are arterial clots described as

Answer 3

white thrombi

Question 4

what are venous clots described as

Answer 4

red thrombi

Question 5

what factors influence thrombosis

Answer 5

the three factors that make up Vircows triangle

1. changes in blood flow (stasis or turbulence)
2. vessel wall dysfunction
3. change in blood components, leading to hypercoaguability

Question 6

what are deep vein thrombosis

Answer 6

a venous thrombosis that originates in the deep vein of the leg

Question 7

how is a DVT formed

Answer 7

it is thought that a DVT process starts within the pocket of one of the valves that line the veins, where flow may be turbulent and localised hypoxia may develop, resulting in endothelial dysfunction

Question 8

what is a thrombus called when it reaches the popliteal vein or above

Answer 8

proximal DVT

Question 9

what are risk factors for DVT

Answer 9

• stasis related factors ie surgery, bed rest

- hypercoaguability ie cancer, surgery

Question 10

what are typical features of DVT

Answer 10

• limb pain
• limb redness, warmth and swelling
• tenderness along vein
• unilateral pitting oedema

Question 11

what is a pulmonary embolism

Answer 11

A pulmonary embolism is a blocked blood vessel in your lungs. It can be life-threatening if not treated quickly.

Question 12

how does a pulmonary embolism present

Answer 12

• pleuritic chest pain
• breathlessness
• haemoptyosis
• tachycardia
• tachypnoea
• crackle and pleural rub

Question 13

investigations for DVT

Answer 13

• ECG - right ventricular strain pattern may be seen, T wave inversion in the inferior (II,III and AVF) and right precordial (V1-V4)
• chest x ray
• arterial blood gas analysis - hypoxia and hypocapnia
• biomarkers of cardiac injury ie an elevated BNP due to stretching of the right ventricle

Question 14

how to diagnose DVT

Answer 14

• Wells score = risk scoring
• measure of D dimer - used to rule out a VTD ie if D dimer has a low pre test probability and the D dimer score falls below pre defined cut off
• ultrasound of the deep venous system and peripheral venous system - a positive scan will confirm the diagnosis
• further assessment required

Question 15

how to diagnose a PE

Answer 15

• Wells score = risk scoring
• measure of D dimer - used to rule out a VTD ie if D dimer has a low pre test probability and the D dimer score falls below pre defined cut off
• imaging is essential in those who have a raised D dimer or are characterised to have a likely PE based on the wells score = computed tomographic pulmonary angiography

Question 16

how is the time scale important for diagnosing a VTD

Answer 16

• should be performed urgently and completed within 24 hours of initial presentation.
• when imaging is required, first does of anticoagulant should be given if its anticipated that it will take more than an hour to investigate a PE and 4 hours for a DVT

Question 17

what is initial treatment for a DVT and a PE

Answer 17

• Parental anticoagulant ie low wight molecular heparin - provide almost immediate anticoagulation therapy
• warfarin needs at least 5 days to provide anticoagulation
• direct oral anticoagulants
  Edoxaban and dabigatin follow after 5 days on LMWH
  Apixaban and rivoxaban do mot require parental anticoagulation

Question 18

how long does treatment with anticoagulation need to continue for

Answer 18

3 months in all patients with DVT or PE because discontinuation can lead to reoccurrence

Question 19

when is the risk of recurrence higher

Answer 19

• males
• those with second events
• those with a PE or a PVT rather than a DVT
• those whose initial presentation is a PE rather than a DVT

Question 20

what is the treatment of unprovoked VTE

Answer 20

• consideration of long term anticoagulation in those with an unprovoked proximal DVT
• Offer of long term anticoagulation in those with unprovoked PE