Thrombosis and Embolism Flashcards
What is a thrombosis?
Clotting occurring at site NOT associated with hemorrhage threatening injury
A thrombus is formed from what?
plasma fibrinogen and platelets
Where do these form, and what are they?
lines of Zahn: a thrombus in the heart or large arteries is formed of layers of fibrin and platelets (pale) and darker layers of RBCs
heart, larger arteries
shows flowing blood has coagulated in high shear
How do postmortem clots differ from antemortem?
They are not attached to vessel walls, therefore easily removed, and are shiny and gelatinous. They are usually red and may show separation of red cells and plasma.
What disorder might be associated wtih microvascular thrombi, present in small arterioles, venules, and capillaries?
Disseminated intra-vascular coagulation
A pulmonary embolism is an example of a venous/arterial thrombosis.
Venous
The causes for a venous thrombosis typically occur from a combination of factors in _____ triad. What are the three factors?
Virchow’s Triad
endothelial injury, abnormal blood flow, hypercoagulabiiity
What might cause venous stasis, or reduced blood flow in veins, which then may cause venous thrombi?
immobility (being bed bound)
increased venous pressure (heart feailure, pregnancy – pressure on iliac veins bc of uterus, obesity)
What might cause arterial thrombosis?
Rupture of atherosclerotic plaque, aortic aneurysm (an excessive localized enlargement of an artery caused by a weakening of the artery wall) arterial stent
What type of endothelial damage may cause venous thrombosis?
Rather than true “damage” (ie surgery), it’s more typically proinflammatory activation, maybe due to hypoxia, chemotherapy, or smoking
What type of venous thrombosis is more likely to metastasize to lung?
more proximal deep venous thrombosis, such as internal iliac vein
Why would DVTs be more likely to happen around valves of calf veins?
reduced flow of oxygenated blood in veins, and these venous valves have no vasculation…endothelium becomes hypoxic.
Then, endothelium around valves responds by expressing adhesion molecules that attract leukocytes
There are four options for what happens to a thrombosis. What are they?
- resolved by fibrinolytic activity.
- breaks loose, forms embolus.
- obstructs important vessel
- fibroblasts and capillaries proliferate, invade base of thrombus, organize into vascularized connective tissue. capillary channels anastamose and recanalize occluded vessel and reestablish the blood flow
A rare (but super dangerous! 80% mortality) complication of labor is amniotic fluid embolism. What happens?
Infusion of amniotic fluid or fetal tissue into maternal circulation through a tear in the placental membranes or rupture of uterine veins. the reason this is problematic is not because your vessels get obstructed, but most likely allergic reaction to fetal products
What is a fat embolism, and what does it cause? How dangerosu is it?
After bone fractures or marrow necrosis, fat +/- hematopoietic cells enters circulation and embolizes to lung. Usually, no consequences–but in 10% of patients, you may see some symptoms because of anemia or pulmonary insufficiency
