Haematology 2 - venous thrombosis Flashcards
Consequences of thromboembolism
Death
Recurrence (20% in firsrt 2 years, 4% per annuum thereafter)
Thrombophlebitis syndrome
Pulmonary HTN
Virchow’s triad
Vessel wall
Blood flow
Blood
What is TFPI? What does it stand for and what does it do?
Tissue factor pathway inhibitor
Inhibits tissue factor 10a and factor 7a
What does antithrombin inhibit?
Thrombin and factor 10a
What property does the vessel wall normally have?
Normally antithrombotic
What factors determine the viscocity of the blood?
Platelet count, haematocrit, protein/paraprotein, coagulation system, coagulation system
Which anticoagulant molecules does the vessel wall express?
Endothelial Protein C receptor
Thrombomodulin
Heparans
TFPI
Where is tissue factor found?
It is found in the subendothelial space, NOT expressed by the vessel wall
What does the vessel wall secrete?
Prostacyclin (PGI2) from vessel wall, Nitric Oxide (NO)
What does inflammation/injury do to the vessel wall?
Makes it prothrombotic
Which factor confers the highest risk of thrombosis?
Antithrombin III deficiency
Immediate anticoagulant therapy
heparin and DOACs
Delayed anticoagulant therapy
Warfarin
How does heparin work?
Potentiates antithrombin
Disadvantages of heparin/DOACs
Osteoporosis, injections, variable renal dependence
Examples of DOACs
Directly acting anti-10a e.g. rivaroxaban, apixaban, anti-2a/anti-thrombin e.g. dabigatran
How do you monitor LMWH therapy?
Factor Xa assay (only required in some patients)
Which patients require LMWH monitoring?
Extremes of weight or renal failure
How do you monitor unfractionated heparin ?
APTT or factor Xa assay (ALWAYS monitor)
Do DOACs require monitoring?
No
Which factor has the shortest half life?
Factor 7
When a patient is started on warfarin, what is the first factor to be depleted?
Factor 7
Warfarin MOA
Vitamin K epoxide reductase inhibitor
Which factors does warfarin inhibit?
Factors 2,7,9,10 and protein C and S
