Venous Thrombosis

Question 1

what does an arterial thrombotic event lead to

Answer 1

Coronary thrombosis (MI)
Cerebral (stroke)
Peripheral

Question 2

what does a venous thrombotic event lead to

Answer 2

DVT

Pulmonary embolism

Question 3

what leads to blood clots in arteries

Answer 3

atherosclerosis

cholesterol plaque builds up in artery narrowing it and causing hypoxia (angina, claudication pain)

atherosclerotic plaque ruptures and exposes collagen

collagen attracts platelets, platelet clot comes and completely occludes the vessel leading to complete tissue infection (platelet rich thrombus)

Question 4

how do you treat arterial thrombosis

Answer 4

aspirin and other anti-platelet drugs

modify risk factors for atherosclerosis

Question 5

causes of venous thrombosis

Answer 5

low pressure system - stasis problem, blood sits there and congeals and forms a fibrin clot

coagulation cascade activated which is rich in FIBRIN CLOT

Question 6

treatment of venous thrombosis

Answer 6

anticoagulants - warfarin, heparin, new oral anticoagulants

Question 7

what is Virchow’s triad in venous thrombosis

Answer 7

Stasis (blood not moving)

Vessel wall (deterioration of the valves in the vessels, caused by age, or previous clot)

Hypercoagulability (elevated levels of clotting factors eg, in acute response if unwell makes you more prone to forming blood clots) OR low levels of natural anti-coagulants (protein S, protein C)

Question 8

presentation of deep vein thrombosis

Answer 8

limbs feel hot
swollen
tender
pitting oedema

Question 9

how can DVT cause PE

Answer 9

clot goes up through IVC, into right side of the heart and then through into the lungs

Blood clot gets stuck in the smaller vessels of the lungs blocking off the venous blood supply

Question 10

presentation of PE

Answer 10

pleuritic chest pain (every time you take a breath the lung irritates the pleura causing acute pain)

cardiovascular collapse/death

Right sided heart strain on ECG - backing up of blood into the right side of the heart?

Hypoxia

Question 11

risk factors for venous thromboembolism (STASIS)

Answer 11

Stasis:

• age
• obesity
• pregnancy
• previous DVT/PE
• trauma/surgery
• malignancy
• paralysis

Question 12

Risk factors for venous thrombosis (VESSEL WALL)

Answer 12

vessel wall:

• age
• previous DVT/PE

Question 13

risk factors for venous thrombosis (hYPERCOAGULABILITY)

Answer 13

• age
• pregnancy (increased clotting factors in pregnancy to prevent haemorrhage in birth)
• puerperium
• oestrogen therapy (same problems as pregnancy)
• trauma/surgery
• malignancy
• infection
• thrombophilia

Question 14

what goes wrong in normal haemostatic system to increase change of thrombophilia

Answer 14

decreased anticoagulant defences

increased coagulation activity (not common, antiphospholipid syndrome)

decreased fibrinolysis (rare)

Question 15

what is thrombophilia

Answer 15

familia or acquired disorders of the haemostasis mechanism which are more likely to predispose to thrombosis

Question 16

what does anti-thrombin do

Answer 16

Serine protease inhibitor

binds to thrombin and switches it off

(if anti-thrombin deficiency you’re at much higher risk of thrombosis)

Question 17

what do proteins C and S do

Answer 17

switch off factor V and factor Xa

factor V leiden is a problem in switching off factor 5 - causes 5x risk of thrombosis

Question 18

what are hereditary thrombophilias

Answer 18

group of genetic defects in which theres an increased tendency to develop premature unusual and recurrent thrombosis

Question 19

what are the hereditary thrombophilia’s

Answer 19

Factor V Leidin 
Prothrombin 20210 mutation 
Antithrombin deficiency 
Protein C deficiency 
Protein S deficiency

Question 20

when would you screen for hereditary thrombophilia

Answer 20

Venous thrombosis <45 
Recurrent venous thrombosis 
Unusual venous thrombosis 
Family history of venous thrombosis 
Family history of thrombophilia

Question 21

management of hereditary thrombophilia

Answer 21

Advice on avoiding risk

Short term prophylaxis (to prevent thrombotic events in times of increased risk)

Short term anticoagulation (to treat thrombotic events)

Long term anticoagulation (if recurrent thrombotic events)

Question 22

why do some people with thrombophilia never have a thrombosis

Answer 22

because to have a thrombotic event a number of risk factors have to go together

not necessarily enough to just have the thrombophilia but if thrombophilia + another risk factor eg. OCP = thrombosis

Question 23

what has to be balanced when considering long term anticoagulation

Answer 23

risk of recurrent thrombosis vs risk of serious haemorrhage

Question 24

causes of ACQUIRED thrombophilia

Answer 24

antiphospholipid antibody syndrome

stronger risk factor for thrombosis than hereditary thrombophilias

Question 25

how does antiphospholipid syndrome present

Answer 25

recurrent thrombosis
(arterial, including TIAs AND venous)

recurrent fetal loss (thrombosis in the placenta)

mild thrombocytopenia

Question 26

what do anti-phospholipid antibodies do

Answer 26

causes a conformational change in b1 glycoprotein 1

causes activation of both primary and secondary Haemostasis and vessel wall abnormalities

antibodies interfere with tests giving false positive clotting factor tests (APTT prolonged but not prone to bleeding, prone to clotting)

Question 27

conditions associated with antiphospholipid antibodies

Answer 27

autoimmune disorders 
lymphoproliferative disorders
viral infections 
drugs 
primary

Question 28

treatment of anti-phospholipid syndrome

Answer 28

Aspirin

Warfarin

(need to treat both primary and secondary homeostasis)