Venous Thrombosis Flashcards by Joanna Mitchell

What will an arterial thrombotic event lead to?

MI
Stroke
Peripheral - critical limb ischaemia

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What will a venous thrombosis lead to?

DVT

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Describe an arterial thrombus?

Due to high pressure system and formation of atherosclerotic plaque
Plaque rupture leads to platelet aggregation and soft plug forming
PRIMARY HAEMOSTASIS
Platelet rich thrombus

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How is an arterial thrombus treated?

Aspirin
Clopidogrel
Modify risk factors for atherosclerosis

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Describe a venous thrombosis?

Low pressure system
Platelets NOT activated
SECONDARY HAEMOSTASIS
Fibrin rich clot

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What is the treatment for a venous thrombosis?

Warfarin
Heparin
DOACs

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What is virchow’s triad?

Stasis
Vessel wall abnormality
Hypercoagulability

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What is the single biggest risk factor for a venous clot?

A previous clot

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Describe a DVT affected leg

Hot
Swollen tender
Pitting oedema
DDx; cellulitis

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Describe a PE

Pleuritic chest pain 
CV collapse 
Death
Hypoxia
Right heart strain 
ECG; right axis deviation (negative lead 1, positive aVF), tachycardic 
Rarely; S1Q3T3

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What is the risk of VTE?

1/1000 per annum
Young adults; 1/10,000 per annum
Elderly 1/100 per annum
Lifetime risk is 2.5%

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What are risk factors for increased stasis in VTE risk?

Age
Marked obesity
Pregnancy
Previous DVT/PE 
Trauma/ surgery 
Malignancy
Paralysis

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What are risk factors for VTE that fall under vessel wall?

Age; decreased collagen

Previous DVT/ PE; damage to valves

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What are the risk factors fro VTE that fall under hypercoaguability?

Age
Pregnancy
Puerperium
Oestrogen therapy 
Trauma/ surgery 
Malignancy
Infection 
Thrombophilia

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Why are the hypercoagulable states associated with increased risk of VTE?

Release of tissue factor
Increased VWF
Increased factor 8

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What is a thrombophilia?

Familial or acquired disorder of haemostatic mechanism which is likely to predispose to thrombosis

What are the mechanisms of thrombophilia?

Increased coagulation activity; platelet plug formation, fibrin clot formation
Decreased fibrinolytic activity
Decreased anticoag activity

What is the most common mechanism for thrombophilia?

Decreased anticoag activity

What will anti-thrombin act on?

TF/ factor 7a
5/10a
8/9a
Thrombin

Can you have a deficiency in anti-thrombin?

Yes

What is factor 5 leiden diseaes?

COMMONEST thrombophilia

Change in factor 5 that means protein C and S can’t turn it off

What are the different types of hereditary thrombophilias?

Factor 5 leiden - 5 fold increase
Prothrombin 20210 mutation - 2 fold increase 
Antithrombin deficiency
Protein C deficiency
Protein S deficiency

In what cohort of people should you consider hereditary thrombophilia screening?

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

What is the management of a hereditary thrombophilia?

Avoidance of risk
Short term prophylaxis at time of high risk e.g. planned surgery
Short term anticoagulation to treat thrombotic events
Long term anticoag for RECURRENT thrombotic events

How can the risk of recurrent thrombosis be assessed?

Clinical history much more important than results of thrombophilia screening History of previous thrombosis Spontaneous thrombosis rather that acquired transient risk factor Family history Thrombophilia screen results

What is the commonest acquired thrombophilia?

Antiphospholipid antibody syndrome

What are the features of APS?

Recurrent arterial AND venous thrombosis Recurrent foetal loss Mild thrombocytopenia

What is the pathogenesis of APS?

Abs lead to conformational change in beta-2 glycoprotein 1 which leads to activation of both primary and secondary haemostasis and vessel wall abnormalities

What will APS do to the screening fibrin clot tests?

``` Increased APTT (same result as heparin) Lupus anticoagulant interferes with assay prolonging APTT even though they are prone to clots and therefore would expect a short APTT ```

What will prolong the APTT?

Haemophilia Heparin treatment APS Mixed factor abnormalities

What are conditions associated with antiphospholipid antibodies?

``` Autoimmune disorders Lymphoproliferative disorders Viral infections; EBV Drugs Primary APS ```

What is the treatment of APS?

Activation of both primary (arterial) and secondary (venous) haemostasis Need to treat the problem they have; arterial clots = aspirin, venous clots = warfarin

Why is warfarin particularly good in APS?

Has action on venous and arterial system | APS is the only condition where warfarin is indicated in place of DOACs