Pathophysiology Of Thrombus And Embolism Flashcards
What factors cause the formation of a thrombus?
Virchows triad:
Changes in blood flow (stagnant or turbulent)
Changes in blood vessel wall
Changes in viscosity of blood
What may cause changes in blood flow?
Stagnant: post op, economy class syndrome
Turbulent: atheromatous plaque, aortic aneurysm
What is the definition of a thrombus?
The formation of a solid mass from the constituents of blood within the vascular system
What can cause a change in blood constituency ?
Post traumatic hypercoagubility
Polycythaemia
Increase in constituents of blood
Describe the pathogenesis of thrombus formation from an athermatous plaque.
Formation of fatty streak causes increase in blood turbulence
This causes RBC and platelet clumping
This causes endothelial damage exposing endothelial collagen
The platelet and collagen aggregate forming fibrin meshwork
This creates further turbulence and platelet aggregation
The RBC get trapped which forms layers of zhan
This can then lead to propagation and perhalps embolism
What does the consequences of a thrombus depend on?
Site
Extent
Collateral circulation
What are the common clinical consequences of thrombus formation?
Deep vein thrombosis
Ischaemi limb = gangrene
myocardial infarction
What is the definition of embolism?
The movement of abnormal material in the bloodstream and its impact on a vessel, blocking its lumen
What is an embolus?
A detached solid mass, liquid or gas that has dislodges into the blood stream.
What are the types of emboli?
Thrombus: arterial/systemic thromboembolism & venous thrombus Fat Bone marrow Foreign body Air Gas Tumour Septic material Trophoblast Amniotic fluid
A patient visits the A and E suffering from a fractured femour. He has now became confused and his skin has an unusual pallor. What might be the cause of this?
A fat embolism
This is because fat emboli can arise after major fractures as the fat may dislodge from the bone marrow into the blood stream.
Syndrome of fat embolism affects the kidneys, brain and skin.
What are the factors causing arterial/systemic thromboembolism?
Mural thrombus (from MI, right atrial dilatation + atrail fibrillation)
Aortic aneurysm
Atheromatous plaque
Valvular regurgitations
What are the factors causing venous embolism?
Post op
Lack of movement
Long flights
What are the factors causing embolism other than thromboembolism?
Fat- major fractures
Air- CV lines, head and neck injurys, surgery
Gas- diving: N2 forms bubble which lodges into the bloodstream
Amniotic- fluid may go into woman during birth
Trophoblast- part of the placenta may dislodge into the mothers bloodstream
Foreign body- suture, IV cannulae tips
Septic material- i.e infective carditis ( vegetation of the heart valves may break off and dislodge into the bloodstream)
Bone marrow- fractures
what factors can cause defects in blood flow?
atheroma hyperviscosity vasospasm vasculitis vascular steel syndrome external compression
