Thrombotic Disorders Flashcards
What is a thrombus?
Clot arising in the wrong place
What is a thromboembolism?
Movement of clot from primary site
What is Virchow’s triad?
Vessel wall damage (atherosclerosis, trauma), stasis (bed rest, travel) + hypercoagulability (pregnancy, trauma)
What are the categories of thrombosis?
Arterial
Venous
Microvascular
What are arterial thrombus made up of?
Platelets (main component) and fibrin
What are the outcomes of arterial thrombosis?
Ischaemia and infarction
What is the most common cause of arterial thrombosis?
Rupturing atherosclerotic plaques
What are some common examples of arterial thrombosis?
MI, stroke, limb ischaemia and unstable angina
What are the risk factors for arterial thrombosis?
Age Smoking Sedentary lifestyle Hypertension Diabetes mellitus Obesity Hypercholesterolaemia
How is arterial thrombosis managed?
Primary prevention- lifestyle modification and treatment of vascular risk factors
Acute presentation- thrombolysis and antiplatelet/anticoagulant drugs
Secondary prevention
What are venous thrombus made up of?
Fibrin (main component) and red cells
What are the outcomes of venous thrombus?
Back pressure which causes valvular insufficiency resulting in post-thrombotic syndrome which can persist for up to two years following the thrombus
What are some examples of venous thromboembolism (VTE)?
DVT PE Visceral venous thrombosis Intracranial venous thrombosis Superficial thrombophlebitis
What are the risk factors for VTE?
Increasing age
Pregnancy
Hormonal therapy (COCP/HRT)
Tissue trauma
Immobility
Surgery (not just due to immobility, vessel damage in surgery causing release of prothrombotic factors. Outpatient surgery still a risk factor. Risk up to 12 weeks post operatively)
Obesity
Systemic disease (malignancy- especially GI tract and pancreatic cancers, haematological cancer, myeloproliferative neoplasm and autoimmune disease ie IBD, SLE, antiphospholipid syndrome)
Family history (first degree relatives only)
Smoking not shown to increase risk
How is VTE diagnosed?
Pretest probability scoring (Wells Score)
Laboratory testing (D-dimer)
Imaging.
There is a specific Wells score for PE.
If probability is high on a Wells score then go straight to imaging.
In low risk individuals a D-dimer can be done and follow up imaging if this is positive.
Imaging is usually a Doppler US
PE investigated with a ventilation/perfusion (V/Q) scan or CTPA. CXR usually done prior to eliminate other causes
What are the aims of management of VTE?
Prevent clot extension
Prevent clot embolization
Prevent clot recurrence in long term treatment
How long should anticoagulants be given following a VTE?
3 months following a VTE. Long term treatment can be given if there are ongoing risk factors that will persist beyond the 3 months
What drugs can be used to give anticoagulation following a VTE?
LMWH (used in malignancy and pregnancy)
Coumarins (warfarin)
DOACs (contraindicated by metallic heart valve)
Thrombolysis only in selected cases (massive PE)
What are the causes of heritable thrombophilia?
Factor V Leiden mutation (most common) Prothrombin mutation Antithrombin deficiency (only condition where family testing indicated) Protein C deficiency Protein S deficiency
What are the characteristics of microvascular thrombi?
Made of platelets, fibrin or both
Results in diffuse ischaemia.
Generally limited to severely ill patients in ITU/HDU settings.
Usually caused by disseminated intravascular coagulation (DIC).
There is a drive towards both clot formation and breakdown, but as the clotting factors become exhausted there is a risk towards bleeding.
Digital ischaemia most common presentation
What conditions can cause disseminated intravascular coagulation?
Septicaemia
Malignancy
Eclampsia
What are the possible outcomes of disseminated intravascular coagulation?
Tissue ischaemia and can result in gangrene or organ failure
