Thrombosis and embolism Flashcards
What is normal flow of blood in vessels?
Laminar flow, that is smooth and ordered
What is abnormal flow of blood?
Turbulent flow or stasis of blood
Name the components of Virchow’s triad
- change in the wall of blood vessel, 2. change un the pattern of blood flow, 3. change in the blood constituents
Define thrombus
solid mass from constituents of blood within the vascular system during life within the vascular system
What is the pathogenesis of thrombus formation?
endothelial injury, stasis of blood or turbulent blood flow, hyper coagulability
Describe the sequence in thrombus formation
endothelium is lost and sticky surface of the plaque is exposed, fibrin and platelets deposit on the surface of the plaque and exposed collagen, fibrin meshwork is formed and RBC become trapped within this network, this gives characteristic lines of Zahn appearance, this leads to further turbulent flow, damage to endothelium and propagation of thrombus
What are lines of Zahn?
alteration of fibrin network interspersed with RBC or platelets, this form characteristic appearance of red and white lines
What are the risk factors for thrombosis?
Hypercholesterolaemia, hypercoagulability
What is mural thrombus ?
Thrombus adhered to one side only, in endothelium of heart or aorta
What is parietal thrombus?
Thrombus that adhere to one side only, to the wall of arteries
What are the possible outcomes of thrombosis ?
resolution, organisation and recanaisation, propagation, death
What is resolution?
The clot dissolves either spontaneously or due to thrombolysis
What is organisation and recanalisation?
The process in which the thrombus is stabilised, it does not propagate, blood flow is restored by formation of new blood vessels in the fibrous tissue
What are the types of embolism based on the locations or the point of entry?
arterial, paradoxical, venous
What is arterial or systemic thromboembolism ?
Embolus that is circulating in the arterial circulation, most commonly formed in the heart, it can cause occlusion in any part of the body, the end result is infarction or ischaemia
What is paradoxical embolus?
Embolus that arise fromm venous circulation and crossed to arterial circulation, it is usually due to septal defect
What is venous embolus ?
Embolus that travels in venous circulation, most commonly arise in deep veins and causes pulmonary embolism
What are the risk factors for embolism?
Heart failure, post-op, postpartum, severe trauma, burns, nephritic syndrome, oral contraceptive pills, age, obesity, bed rest and immobilisation, family history and previous emboli
What are the types of emboli based on the material?
Fat, gas, air, amniotic fluid, trophoblast, tumour, septic material, bone marrow, foreign bodies
What us fat embolus?
Fat macromolecules that are broken off and traveling in the systemic circulation, they arise after major fractures, soft tissue injuries, orthopaedic procedures, severe burns, bone marrow biopsy, liposuction, fatty liver, prolonged corticosteroid therapy, end results is syndrome of fat embolism
What is the syndrome of fat embolism?
Results from fat embolus occlusion, breathlessness, respiratory failure, cerebral dysfunction and petechial rush
What is gas embolus?
Bubble of gas traveling around body in circulation, caused by decompression sickness (gas comes out of solution on decompressurisation), the symptoms can very from pain, rashes to paralysis and death, e.g. N2 gas from underwater decompression
What is air embolus?
Air in the circulation, arise from head and neck wounds, surgeries and CV lines, again various symptoms
What is tumour embolism?
When parts of tumour break off and travel around the body in blood, it is possible cause of spread of tumours
