Flashcards in L26. Vascular Pathology Deck (20):
How is the endothelium normally an anti-clotting surface?
Produces thrombomodulin which inhibits thrombin (and thrombosis)
Produces Protein C and Protein S which change thrombin from a pro into anti thrombotic factor
What is a thrombus?
An abnormal clotted mass of blood in an unruptured cardiovascular system (Ie. blood clot formed without needing to be formed or persisting long after it needs to)
What are the components of clotted blood?
RBCs, WBCs, Platelets and Fibrin
What causes the formation of layers of red and white in these clots? What are these called?
Thombosis occurs in FLOWING BLOOD leading to the formation of clumped cells and platelets followed by fibrin formation and then more clots and then fibrin causing this streaked appearance = LINES OF ZAHN
What causes thrombosis?
An imbalance between thrombogenesis and thrombolysis
What is the difference between arterial and venous thrombi?
Their formation, appearance and treatments
Higher platelets in the clot
White Thrombus due to endothelial dysfunction or damage (high stress environment)
Aspirin is more useful for the prevention of arterial thrombosis
Higher red cells
Red thrombus due to blood stasis or hypercoaguability causing accumulation of clotting factors
Warfarin is more useful for preventing venous thrombus
Why is aspirin better in prevention of arterial thrombosis and warfarin better for venous?
Because aspirin (a blood thinner) prevents thromboxane formation in platelets (arterial clots are platelet heavy). And warfarin is an anti-coagulant which prevents the formation of clotting factors and coagulatives in the blood (venous thrombosis is a result of hypercoaguability)
What underlying abnormalities lead to thrombosis?
1. Abnormal endothelium: loss of endothelium and vWF and TF exposure, dysfunction due to inflammation, reduced anticoagulant activity
2. Abnormal Flow: turbulence, stasis, loss of laminar flow,, accumulation of active platlets
3. Abnormal contents: genetic problems, oestrogen (pill or pregnancy), cancer, smoking, obesity, age and others
What are the possible outcomes of thrombosis? 
1. Dissolution (fibronlysis)
2. Organisation and recanalisation (granulation tissue)
3. Propagation (grow longer and more crumblier due to continual platelet activation)
4. Embolism (mass carrier through the blood stream)
What is an embolus?
An intravascular mass carried in the blood that can be solid, liquid or gaseous carried to a remote site from its origin or point of entrance causing blockage of the vessel.
Describe an arterial embolism
Usually occurs as a result of turbulence in the blood.
The thromboembolis gets stuck in a downstream (smaller) artery causing ischaemia to an organ that the artery supplies (eg. the brain, intestines, kidneys, legs, spleen).
Describe a venous embolism
Significant thromboemboli usually arise in the deep veins of the legs or pelvis and travels back into the veins and drains into the right side and often lodge in the pulmonary arteries (Pulmonary Embolism)
What is ischaemia? What is infarction?
Ischaemia is when there is not enough blood supply and infarction is tissue death as a result of inadequate blood supply.
What are some causes of Ishaemia? 
Local vascular narrowing or occlusion (stops oxygen delivery)
Increased demands for oxygen that are not met (eg. angina)
Systemic reduction in tissue perfusion (like cardiac or respiratory failure)
What are some examples of acute ischaemia?
Coronary thrombosis leading to MI
Thromboembolism to the brain causing ischaemic stroke or transient ischaemic heart attack (TIA)
Atheroscelrotic narrowing causing claudication and angina
Torsion or twisting of some areas blocking a vein
Shock - reduced blood volume
What are some examples of chronic ischaemia?
Atherosclerotic disease leading to atrophy
Renal artery stenosis causing renal atrophy
Hyaline atherosclerosis leading to benign nephrosclerosis
What kind of vessel is the main problem (occluded) causing infarction?
Mainly arteries being blocked: because they deliver the oxygen
What are the outcomes of infarction? What does it depend upon?
Depends upon the type of tissue
- Some are more sensitive (eg. Neurons die within minutes)
- Some have multiple blood supplies that can compensate somewhat
- Some have collateral supplies that are activated upon chronic ischamiea
What kind of necrosis occurs in the heart as a result of infarction?
Death of cardiac cells that leads to ghost outlines of cells followed by acute inflammation and from the cell content leakage. Then to healing by granulation tissue and eventual scar formation