Thrombotic Disorders Flashcards
3 main elements of haemostasis
Primary haemostasis
Blood coagulation
Fibrinolysis
Steps of primary haemostasis?
Vessel wall damage leads to:
Vasoconstriction,
Causes platelet adhesion,
Resulting in platelet aggregation
= Primary plug
What does primary haemostasis lead to?
A coagulation cascade:
- insoluble fibrin formation
- fibrin cross-linking
Steps of fibrinolysis?
Urokinase and tissue plasminogen activator (tPA) and factor XII
Cause plasminogen to be converted into plasmin.
Plasmin then converts fibrin into fibrinogen/ fibrin degradation products
Define thrombus
Clot arising in the wrong place
Define thromboembolism
Movement of clot along a vessel
What is Virchow triad (HvS Hayden vs Skye for Zoe)
Triad of thrombus formation:
Stasis
Hypercoagulability
Vessel damage
Examples for each of Virchow triad?
Stasis:
- bed rest,
- travel
Hypercoagulabiltity:
- pregnancy
- trauma
Vessel Damage:
-atherosclerosis
Types of thrombosis?
Arterial
Venous
Micro vascular
Main cause of arterial thrombus?
Platelets
Called white clot
Can also be caused by fibrin
Principally secondary to atherosclerosis
what does arterial thrombus result in?
Ischaemia
Infarction
Examples of arterial thromboembolism?
Coronary- MI, unstable angina
Cerebrovascular- stroke, TIA
Peripheral embolism- limb ischaemia
Risk factors for arterial thrombosis
Age, Smoking, Sedentary lifestyle, Hypertension, Diabetes mellitus, Obesity, Hypercholesterolaemia
Management of arterial thrombosis
Primary prevention:
- lifestyle modification
- treat vascular risk factors
Acute presentation:
- thrombolysis
- antiplatlet/ anticoagulant
Secondary prevention
What causes venous thrombus
Fibrin and red cells
So called “red thrombus”
This causes back pressure
Principally due to stasis and hypercoagulability
Examples of venous thromboembolism
Limb deep vein thrombosis Pulmonary embolism Visceral venous thrombosis Intracranial venous thrombosis Superficial thrombophlebitis
Risk factors of venous thrombosis
Stasis/ hypercoagulability Increasing age, Pregnancy, Hormonal therapy, Tissue trauma, Immobility, Surgery, Obesity, Systemic disease, Family history
Systemic diseases that can cause venous thrombosis
Cancer, Myeloproliferative neoplasm Autoimmune disease: -IBD -connective tissue disease eg SLE -antiphospholipid syndrome: arterial and venous thrombosis
How to diagnose venous thrombosis
Protest probability scoring: -Wells score -Geneva score Ddimer Doppler ultrasound, V/P scan CT pulmonary angiogram
Aim of treatment for venous thrombosis
Prevent clot extension,
Prevent clot embolisation,
Prevent clot recurrence in long term treatment
Drugs used to treat venous thrombosis
Anticoagulants- LMWH, coumarins (warfarin), DOACs
Thrombolysis in massive PE
What is heritable thrombophilia
An inheritable predisposition to venous thrombosis
Causes of heritable thrombophilia
Factor V Leiden
Prothrombin G20210A
Antithrombin defiency
Protein C deficiency
Protein S deficiency
What causes microvascular thrombus??
Platelets and/or fibrin
Results in diffuse ischaemia
Principally in Disseminated Intravascular Coagulation (DIC)
What is DIC
Diffuse systemic coagulation activation
Where does DIC occur
In:
Septicaemia,
Malignancy,
Eclampsia
Due to consumption of platelets and clotting factor leading to bleeding
What does DIC cause?
Tissue ischaemia
Causing:
-gangrene
-organ failure
