Topic 3: Thrombosis, Embolism, Infarction Flashcards
What is the definition of a thrombus?
What is the difference between a thrombus and a blood clot?
What is the normal response to haemorrhage? (3 steps)
Compare haemostasis and thrombosis?
What 4 factors inhibit thrombosis?
- intact endothelial cells
- anticoagulant molecules and platelet inhibition
- fibrinolysis
- lamina flow
What is Virchow’s triad?
- factors that predispose you to thrombosis
What causes changes in the vessel wall?
- injury to or activation of endothelium or exposure of subendothelial layers (collagen)
- atherosclerosis *
- inflammation
- trauma (tumour)
Describe normal blood flow
- laminar
- keeps platelets away from endothelium
What causes stasis and turbulent flow (change in blood flow)?
- disruption of laminar flow
- endothelial activation
- stasis is a major contributor to venous thrombi ( AKA clots)
- veins
- aneurysm, when you get an out pouch of a vessel, lose elasticity
What are changes in the constituents of blood?
- hereditary (factor 5 mutations, deficiency of anticoagulant molecules)
- acquired - more common (increase in coagulation factors, hyperviscosity- reduces flow)
what are 2 types of thrombi?
- venous
- arterial
What are the risk factors for developing DVT (deep vein thrombosis)?
- immobilisation
- post-surgical
- cancer
- pregnancy
- heart failure
- dehydration
What is trousseau syndrome?
when cancer causes venous thrombosis
What are the macroscopic signs of DVT?
- attachment to valves
- -
What are the microscopic signs of DVT?
- full of red cells, darker area
- lighter area, fibrin
- irregular laminations
- granulation tissue
- attempted recanalisation (round empty spaces)
What are some outcomes of DVT?
- resolution
- granulation repair (origination)
- recanalisation
- goes into lungs, embolisation
What are some DVT clinical manifestations?
- swollen
- tender
- identify predisposing factors
- associated warms and redness
What are differential diagnoses of DVT?
What are DVT investigations?
- ultrasound shows the flow of the vein
- plasma D-dimers (broken down fibrin) is a sign of inflammation and would rule out DVT in low-risk individuals
How is DVT prevented?
What is arterial thrombi?
- lins of zahn
- anurysm
What is a microscopic featur of AT?
What are the outcomes of arterial thrombus?
What are the important sites of arterial thrombosis?
What is a mural thrombus?
Where and why does is a mural thrombus in the heart occur?
- left ventricle after myocardial infarct
- left atrium due to atrial fibrillation (change in flow)
- vegetation on damaged valves
What is a macroscopic feature of acute myocardial infarct?
- yellow necrosis
- acute
- thrombus formed over it
- may have caused death, due to decreased perfusion to organs or embolism
What is the difference between thrombus and post-mortem clotting?
Define embolism
- transport by blood of abnormal material and its impaction in a vessel. at a point remote
What are 3 kinds of embolism?
What is venous thromboembolism?
- ## dangerous when it gets to the level of the knee
What is a pulmonary embolism?
What is arterial thromboembolism?
- moves with the flow of blood AWAY from the heart
- lodges in arteries of matching size
- ## causes distal ischaemia
Discuss macroscopic feature of arterial thromboembolic in the heart
- from mural thrombus in the left ventricle following myocardial infarction
What is atherosclerosis?
- 20% of arterial thromboembolism sources
What are the effects of arterial thromboembolic in the leg, brain, kidney/ spleen and gut?
What are the macroscopic features of mural thrombus in the left ventricle
- old infarct, grey tissues due to decreased flow, loss of tissue, thin contracted ventricle wall
- if it was recent would be yellow necrosis or hemorrhage
Define infarction.
- circumscribed area of ischaemic necrosis in an organ or tissue resulting from interference of blood
What are some causes of infarction?
- localised blockage of arterial supply
- systemic hypotension
- blockage of venous drainage
What factors determine the effect of ischaemia?
- rate of occlusion
- extent of occlusion
- systemic factors
- anatomy of local blood supply
(organs that have dual blood supply, liver, pulmonary and bronchial, and liver, systemic and portal) - vulnerability of tissue to ischaemia (brain, heart, huge metabolic requirements)
What is venous occlusion?
- can cause ischaemia due to back pressure and impairment of arterial flow
What are torsion/volvulus and strangulation?
- torsion of testis
What are some macroscopic features of infarcts?
- green
- red
What are the microscopic appearances of infarcts?
What is the evolution of an infarct?
necrosis -> acute inflammatory response -> repair by granulation tissue
What is the time course of infarction?
