pathophysiology of thrombosis and embolism Flashcards
what are the two types of abnormal blood flow?
stasisturbulent
what is static blood flow?
stagnation of flow
what is turbulent blood flow?
unpredictable and forceful
what are the causes of abnormal blood flow?
thromboembolismatheromahyoerviscosityspasmexternal compressionvsculitisvacsular steal
what can cause external compression of blood vessels causing abnormal flow?
a tumour pressing on the vesselbaby pressing on vessels during pregnancy
what is vascular steal?
dilation of one vascular network (e.g., during exercise or vasodilator therapy) “steals” blood flow from another region within the organ that is already maximally dilated because of the presence of proximal lesions.
what is Virchow’s triad of the factors causing thrombosis?
-Changes in the blood vessel wall-Changes in the blood constituents-Changes in the pattern of blood flow
what is the difference between a thrombus and a clot?
a thrombus forms within the vascular system during life.A clot can occur anywhere and postmortem in the vascular system it is called a clot
give an example of a change in vessel wall that can increase the risk of thrombosis?
atheromatous plaque in artery
give an example of three typical changes which lead to thrombosis?
endothelial injurystasis or turbulent blood flowhypercoagulability of blood
what are line’s of Zahn?
alternating bands of red blood cells and platelets with fibrin
give a detailed description of the pathogenesis of thrombosis, starting with an atheromatous coronary artery
- atheromatous coronary artery2. turbulent flow3. loss of intimal cells from denudation of the plaque4. platelets adhere to exposed collagen5. fibrin network forms and RBCs trapped6. lines of Zahn appear7. further turbulence and platelet deposition 8. leads to propagation
what can cause changes in vessel wall that leads to thrombosis?
-myocardial infaction- can lead to mural thrombosis in the heart-turbulent flow- denuding intima
what is a mural thrombosis?
blood clot on the wall of the heart
what factors can lead to changes in blood viscosity, leading to increased risk of thrombosis?
polycythaemia, dehydrated, post-traumatic hypercoagulability
what can lead to stasis of blood flow and then thrombosis?
-long flights sitting down-post operation (bed-bound)
what can cause turbulence of flow which can lead to thrombosis?
atheromatous plaqueaortic aneurysm
what three things do the consequences of a thrombosis depend on?
siteextentcollateral circulation
what are the favourable outcomes of thrombosis?
-resolution-organisation and recanalisation
what are the unfavourable outcomes of thrombosis?
deathpropagation leading to embolism
what is embolism?
Movement of abnormal material in the bloodstream and its impaction in a vessel, blocking its lumen