Thrombotic Disorders Flashcards
What is involved in primary haemostasis?
Vasoconstriction, platelet adhesion (following collagen exposure to damaged vessel wall), activation and aggregation
What does blood coagulation lead to?
Formation of a fibrin clot after the clotting cascade
What occurs in fibrinolysis?
tPA breaks down plasminogen into plasmin
Plasmin breaks down fibrin into fibrin degradation products (one of which is D-dimer)
Define thrombus
Clot arising in the wrong place
Define thromboembolism
Clot moving along a vessel
What is Virchow’s triad?
Factors increasing risk of thrombus formation
Stasis e.g. travelling, in hospital
Hypercoagulability, e.g. pregnancy, trauma
Vessel wall damage, e.g. atherosclerosis
What are arterial thrombi composed of?
Platelets and fibrin
What do arterial clots result in?
Ischaemia and infarction
What are most arterial clots due to?
Atherosclerosis
Give examples of arterial clots
Coronary thrombosis –> MI and angina
Cerebrovascular thromboembolism –> stroke/TIA
Peripheral embolism –> limb ischaemia
What are the risk factors for arterial thrombosis?
Smoking, sedentary lifestyle, HTN, DM, obesity, hypercholesterolaemia
How do you manage arterial clots?
Prevention via modification of lifestyle/risk factors
Acute Rx: thrombolysis and anticoagulation/antiplatelets
Secondary prevention: anticoagulants/antiplatelets
What are most venous thrombi composed of?
Fibrin and red cells
What do venous thrombi result in?
Back pressure
What are most venous thrombi due to?
Hypercoagulability and stasis
Give examples of venous thrombi
DVT, PE
Visceral venous thrombosis
Intracranial venous thrombosis
Superficial thrombophlebitis
What are risk factors for venous thrombi?
Anything increasing hypercoaguability and stasis:
Age, pregnancy, COCP, HRT, tissue damage, immobility, surgery, obesity, systemic disease, FH
What systemic diseases may lead to hypercoagulable state that leads to an increased risk of venous thrombi?
Cancer
Myeloproliferative neoplasms
Autoimmune disease (IBD, connective tissue dx (SLE), antiphospholipid syndrome
How can you assess the probability of venous thrombus?
Geneva/well’s score
What test can you do to test for venous thrombus likelihood?
D-dimer
High levels –> recent intravascular coagulation/fibrinolysis (e.g. from DVT etc.)
What imaging can you use if you suspect a venous thrombi?
Doppler US
VQ scan
CT pulmonary angiogram
How do you treat a massive PE?
Thrombolysis
How do you treat venous thrombi?
Anticoagulants e.g. LMWH, warfarin, DOACs
What does LMWH act on?
10a/thrombin
How does warfarin work?
Decreases numbers of vitamin K dependent factors (2, 7, 9, 10)
What do DOACs act on?
10a
What is heritable thrombophilia?
Inherited predisposition to venous thrombosis (hypercoagulable state)
Give examples of heritable thrombophilias
Factor V leiden
Prothrombin
Antithrombin deficiency
Protein C/S deficiency
Do we screen for heritable thrombophilias?
Only high risk ones e.g. antithrombin deficiency
What are microvascular thrombi composed of?
Platelets +/- fibrin
What do microvascular thrombi result in?
Diffuse ischaemia
When do you tend to get microvascular thrombi?
in DIC - disseminated intravascular coagulation
What is DIC?
Diffuse systemic coagulation activation
When does DIC occur?
Septicaemia, malignancy, eclampsia
What does DIC result in?
Tissue ischaemia (gangrene, organ failure) Consumption of platelets and coagulation factors --> bleeding
