8. Thrombotic disorders Flashcards
What is primary heamostasis
Blood clots
What is the clotting process?
Insoluble fibrin formation
fibrin cross linking
How are clots broken down
Urokinas and tissue plasminogen activator cleave plasminogen into plasmin.
Plasmin degrades fibrin
What is a thrombus
A clot where there shouldn’t be one
What is a thromboembolism
A clot arising in the wrong vessel
What leads to thrombosis?
Stasis, hypercoagulability, vessel damage (virchow’s triad)
Don’t necessary need all three to make a clot
Give an example of some of the factors that cause thrombosis?
Stasis- bed rest, travel
Hypercoagulability- pregnancy(excess oestrogen), trauma
Vessel damage- atherosclerosis
How do you categorise thrombosis?
Arterial
Venous
Micro vascular
Was causes an arterial thrombus
“White clot” platelets and fibrin
Results in ischaemia and infarction
Principally secondary to atherosclerosis rupture
Give some examples of arterial thromboembolism and how they present?
Coronary thrombosis
Cerebrovascular thrombo
What are the risk factors for arterial thrombosis?
Age Smoking Sedentary lifestyle Hypertension Diabetes Obsesity Hyper cholesterolaemia
How do you manage arterial thromboembolism?
Primary prevention- lifestyle modification, treatment of vascular risk factors
Acute presentation- thrombolysis, antiplatelet/ anticoagulant drugs, PCI, limb ischemia- amputation
Secondary prevention- medications to reduce secondary event e.g. clopidogrel,aspirin,
What does rivoroxebam and aspirin do?
Very good at better outcomes of secondary prevention
What is a Venus thrombus?
Red thrombus- fibrin and red cells
Results in back pressure
Principally due to stasis and hypercoagulability
What is post thrombotic syndrome?
Backflow of blood due to floppy valves.
Leads to hyperpigmentation, lower leg swelling and redness.
Very severe cases cause venous ulceration
What are common sites for venous thromboembolism?
Deep vein thrombosis
Pulmonary embolism
Visceral venous thrombosis
Intracranial venous thrombosis
Superficial thrombophlebitis-managed differently
Acute pancreatitis, biliary tree disease- mesenteric vein and splenic vein
Cervical rib- upper limb DVT
What are the risk factors for venous thrombosis?
Increasing age Pregnancy Hormonal therapy Tissue traumaImmobility SurgeryObesity Systemic disease Family history- main risk is venous disease in first degree relatives
What systemic disease can cause venous thrombosis
Cancer- GI cancer, blood malaignancies
Myeloproliferative neoplasm
Autoimmune disease- IBD, connective tissue disease, antiphospholipid syndrome
How is venous thrombosis diagnosed?
Wells score- most widely used.
Genes score
D-Dimer- not applicable in pregnancy
Imaging- Doppler ultrasound (veins compress, arteries don’t. DVT won’t compress),
V/Q scan good. CXR, CT pulmonary angiogram
What is the aim of management?
Prevent clot extension
Prevent clot embolisation
Prevent clot recurrence in long term treatment
What is the job of anticoagulants in venous thrombosis?
Most anticoagulants don’t work directly on the clot they act on the step before the clot is formed.
Anticoagulants prevent the initial clot getting bigger.Anticoagulants for minimum of three months.
Re-assess and if they have long term risk factors they need further prophylaxis
What drugs can be used to treat venous thrombosis?
LMWH- malignancy, Coumarin (warfarins)- esp. if they have metallic heart valve
DOAC- direct oral anticoagualants (avoid pregnancy)
Thrombolysis only in selected cases (massive PE)
What is heritable thrombophilia?
An inherited predisposition to venous thrombosis
Common factor: V Leiden mutation
Also common: prothrombin
Rare- antithrombin deficiency (risk of future clots very high patients present v young), protein C deficiency, protein S deficiency
What is micro vascular thrombosis?
Platelets and/or fibrin
Results in diffuse ischaemia
Principally in disseminated intravascular coagulation
What is Disseminated intravascualr coagulation?
Systemic coagulation,
occurs in Septicaemia Malignancy Eclampsia
Causes tissue ischaemia:Gangrene, organ failure
Consumption of platelets and clotting factors lead to bleeding.
