Thrombotic Disorders Flashcards by Brian Mendonsa

What are the 3 components of haemostasis?

Primary haemostasis
Blood coagulation
Fibrinolysis

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What is primary haemostasis triggered by?

Triggered by tissue damage causing:

Vasoconstriction
Platelet adhesion
Platelet aggregation

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In primary haemostasis, what does tissue damage cause?

Vasoconstriction
Platelet adhesion
Platelet aggregation

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What does the coagulation cascade result in?

Insoluble fibrin formation
Fibrin cross-linking

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What is fibrinolysis?

Plasminogen is converted into plasmin:

Converted by activation factors XI and XII

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What activation factors are required to convert plasminogen into plasmin?

Converted by activation factors XI and XII

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What is plasmin?

This is an enzyme that then converts fibrin into fibrinogen/fibrin degradation products

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What is a thrombus?

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What is thromboembolism?

Thromboembolism = “movement of clot along a vessel”

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Describe the aetiology of thrombosus?

Virchow’s triad components
- Stasis
  - Bed rest
  - Travel
- Vessel damage
  - Atherosclerosis
- Hypercoagulability
  - Pregnancy
  - Trauma

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What are the 3 components of Virchow’s triad?

Stasis

Vessel damage

Hypercoagulability

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What does an arterial thrombus consist of?

Platelets and fibrin

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What are the 3 different kinds of thrombosis?

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Describe the aetiology of arterial thrombosis?

Principally secondary to atherosclerosis

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Describe the risk factors for arterial thrombosis?

Age
Smoking
Sedentary lifestyle
Hypertension
Diabetes
Obesity
Hypercholesterolaemia

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What are possible complications of arterial thrombosis?

Ischaemia and infarction

What are some examples of arterial thrombus disease?

Coronary thrombosis
- Myocardial infarction
- Unstable angina
Cerebrovascular thromboembolism
- Stroke
- TIA
Peripheral embolism
- Acute limb ischamia

Describe the management of arterial thrombosis?

Primary prevention
- Lifestyle modifications
- Treatment of vascular risk factors
Acute presentation
- Thrombolysis
- Antiplatelet/anticoagulant drugs
Secondary prevention

What is a venous thrombus composed of?

Fibrin and red cells

Describe the aetiology of venous thrombosis?

Principally due to stasis and hypercoagulability

What are the risk factors for venous thrombosis?

Increasing age
Pregnancy
Hormonal therapy
- COCP/HRT
Tissue trauma
Immobility
Surgery
Obesity
Systemic disease
- Cancer
- Myeloproliferative neoplasm (MPNs)
- Autoimmune disease
  - Inflammatory bowel disease
  - Connective tissue disease such as SLE
  - Antiphospholipid syndrome
Family history
- Heritable thrombophilia

What are examples of heritable thrombophilia?

Describe the pathophysiology of factor V Leiden?

Normally
- Protein C activated in presence of thrombin
- With protein S, protein C inhibits activated factor VIII and V
But with factor V mutation
- Action of protein C inhibiting factor V is blocked
- Ongoing drive towards thrombin and clot formation

Describe the pathophysiology of protein C or S deficiency?

Factors Va and VIIIa not inhibited

Describe the pathophysiology of antithrombin deficiency?

* Thrombin generation continues and fibrin clot formation

Describe complications of venous thrombosus?

* Back pressure

What are some examples of venous thromboembolic disease?

* Limp deep vein thrombosis * Pulmonary embolism * Visceral venous thrombosis * Intracranial venous thrombosis * Superficial thrombophlebitis

Describe the diagnosis of venous thrombosis?

* Pretest probability scoring * Wells score * Geneva score * Lab tests if pretest probability low * D-dimer * Imaging * Doppler US – for upper and lower limbs * Ventilation/perfusion scan – for lungs * CT pulmonary angiogram – for heart and lungs

What probability scoring is used in venous thrombosis?

* Wells score * Geneva score

What lab investigation can be done for thrombosis?

D-dimer

What imaging is useful for venous thrombosis?

* Doppler US – for upper and lower limbs * Ventilation/perfusion scan – for lungs * CT pulmonary angiogram – for heart and lungs

Describe the management of venous thrombosis?

* Aims * Preventions of clot extension * Prevent clot embolism * Prevent clot recurrence in long term treatment * Drugs * Anticoagulants – do not break down clot but prevent from extending (workings in clotting cascade) * LMWH * Coumarins (warfarin) * DOACs * Thrombolysis – breaks down clot

What is a microvascular thrombus composed of?

* Platelets and/or fibrin

Describe the aetiology of microvascular thrombosis?

* Principally in Disseminated intravascular coagulation (DIC) * Is diffuse systemic coagulation activation * Occurs in * Septicaemia * Malignancy * Eclampsia * Causes tissue ischaemia * Gangrene * Organ failure * Pathophysiology * Whilst forming clots, consumption of platelets and clotting factors leading to bleeding * Activation of coagulation leading to microvascular thrombosis deposition

What is a complication of microvascular thrombosis?

Diffuse ischaemia

What does DIC stand for?

Disseminated intravascular coagulation

What conditions does DIC occur in?

* Septicaemia * Malignancy * Eclampsia

Describe the pathophysiology of DIC?

* Causes tissue ischaemia * Gangrene * Organ failure * Pathophysiology * Whilst forming clots, consumption of platelets and clotting factors leading to bleeding * Activation of coagulation leading to microvascular thrombosis deposition