deep venous thrombosis and pulmonary embolism

Question 1

what is a thrombus?

Answer 1

a pathological clot

Question 2

what are the three things a clot is made up of?

Answer 2

fibrin
platelets
RBCs
(different ratios for different types of clot)

Question 3

describe the pathway for the formation of a clot in an artery?

Answer 3

1. damage to endothelium
2. tissue factor produced
3. prothrombin converted to thrombin
4. thrombin converts fibrinogen into fibrin
5. firbrin foms corss-linked fibrin
6. along with platelets to form a white thrombus

Question 4

what kind of clots thombi form in arteries?

Answer 4

white thrombi, contain few RBCs

Question 5

what kind of thrombus forms in veins?

Answer 5

red thrombus

Question 6

describe the formation of a red thrombus

Answer 6

1. tissue factor and the contact pathway cause the production of thrombin
2. thrombin converts fibrinogen into fibrin
3. fibrin traps RBCs forming a red thrombus

Question 7

what is the most common cause of white (arterial) thrombus?

Answer 7

rupture of atherosclerotic plaque

Question 8

what are the locations of arterial thrombi?

Answer 8

arteries and left heart chambers

Question 9

what are the consequences of arterial thrombi?

Answer 9

ischaemia and infarction

Question 10

what are the disease caused by arterial thrombi?

Answer 10

ACS
ischaemic stroke
limb claudication and ischaemia

Question 11

what is the composition of an arterial thrombus?

Answer 11

white thrombus- platelets and fibrin

Question 12

what is the mechanism for the formation of venous thrombi?

Answer 12

combination of Virchow’s triad especially stasis and hypercoagulability

Question 13

what is the location of origin of venous thrombi?

Answer 13

venous valves and venous sinusoids of muscle

Question 14

what is Virchow’s triad?

Answer 14

stasis
hypercoagulability
endothelial damage/dysfuntion

Question 15

what do venous thrombi result in?

Answer 15

back pressure

Question 16

what are the diseases caused by venous thrombosis?

Answer 16

DVT

pulmonary embolism

Question 17

what is the composition of a venous clot?

Answer 17

red thrombus- RBCs and fibrin

Question 18

what can cause stasis (in Virchow’s triad)

Answer 18

immobility

long haul travel

Question 19

what can cause vessel damage/dydfunction in Virchow’s triad?

Answer 19

dysfunction:
hypertension
smoking
hypercholesterolaemia
damage:
-indwelling venous catheters
-trauma
-surgery

Question 20

what can cause hypercoagulabilty (in Virchow’s triad)?

Answer 20

-inherited causes
-acquired:
pregnancy
cancer
sepsis

Question 21

what is an embolism?

Answer 21

intravascular material that migrates from its original location to a distal vessel

Question 22

what is thromboembolism?

Answer 22

movement of blood clot along a vessel

Question 23

give 4 examples of venous thromboembolism?

Answer 23

limb DVT
pulmonary embolism
visceral venous thrombosis
intracranial venous thrombosis

Question 24

what are the symptoms of DVT?

Answer 24

unilateral limb swelling
persisting discomfort
calf tenderness

Question 25

what are the signs of DVT?

Answer 25

warmth
redness
prominent collateral veins
unilateral pitting oedema

or may be clinically silent

Question 26

when may DVT cause bilateral signs and symptoms?

Answer 26

when there is obstruction of the IVC

Question 27

what are the long-term consequences of DVT?

Answer 27

post thrombotic syndrome
causing damage to venous valves. 
This causes:
swelling
discomfort
pigmentation
ulceration of veins in severe form

Question 28

how is DVT diagnosed?

Answer 28

1. clinical assessment and pretest probability score (Wells score)
2. Blood test: D-dimer if low pre-test probability score
3. imaging compression ultrasound if positive D-dimer or high pre-test probability score

Question 29

what is D-dimer test, in terms of sensitivity and specificity?

Answer 29

-high sensitivity for VTE
-low specificity for VTE
as positive in:
trauma
malignancy
sepsis
bleeding
cancer
recent surgery

Question 30

what are the symptoms of PE?

Answer 30

pleuritic chest pain
dysmpnoea
haemoptysis

Question 31

what are the signs of PE?

Answer 31

tachycardia

pleural rub in ausculatation (due to pulmonary infarction)

Question 32

what are the symptoms of massive pulmonary embolism

Answer 32

severe, sudden dyspnoea

collapse

Question 33

what are the signs of massive pulmonary embolism?

Answer 33

cyanosis (blue lips and tongue)
tachycardia
hypotension
raised JVP
may cause sudden death

Question 34

how is PE diagnosed?

Answer 34

1. clinical assessment and pretest probability score (Wells or Geneva)
2. D-dimer test if low pretest probability score
3. imaging if D-dimer positive or high pre test probability score
   - isotope ventilation/perfusion scan
   - CT pulmonary angiogram

Question 35

what are the potential long-term consequences of pulmonary embolism?

Answer 35

• most recover fully

- pulmonary arterial hypertension

Question 36

what are the aims of treatment of VTE?

Answer 36

prevent clot extension
prevent clot embolism
prevent recurrent clot

Question 37

what are anticoagulation treatments for VTE?

Answer 37

parental options:
-unfractioned heparin
-low molecular weigth heparin
Enteral options:
-Warfarin
-direct oral anticoagulants (DOACs)

Thrombolysis reserved for massive PE
eg. alteplase

Question 38

what are the prevention methods for VTE in hospital?

Answer 38

• early mobilsation
• anti-embolism stockings
• other mechanical methods of thromboprophylaxis
• pharmacological thromboprophylaxis

Question 39

why is pulmonary infarction rare in PE?

Answer 39

dual vascular supply to lungs with anastomoses;
Pulmonary vascular system
Bronchial vascular system

Question 40

what causes infarction in PE?

Answer 40

1. blockage in branch of pulmonary artery
2. leads to increase in pressure within pulmonary vasculature
3. force within bronchial artery may be insufficient to overcome this
4. leakage of blood into alveolar space occurs and leads to infarcion.