Atheroma, Thombus And Embolism. Flashcards
What is a thrombosis?
Pathological corruption of haemostasis. Formation of solid or semi solid mass of blood constituents of blood within the vessels.
What are the two main functions of haemostasis?
Maintain blood in a fluid, clot free state.
Induce haemostatic plug at site of vascular injury.
What is virchows triad?
Changes in the blood vessel wall.
Changes in the blood constituents.
Changes in the blood flow.
What are the functions of an endothelial cell?
Maintains a permeability factor.
Elaborates anticoagulant and prothrombin molecules e.g. Fibrinogen.
Produce ECM.
Modulate blood flow and vascular permeability.
Regulates inflammation and immunity.
Regulates cell growth.
Play a role in LDL oxidation.
What is hyaline arteriosclerosis?
Plasma proteins forced into the vessel walls?
What is hypercoagulability?
Any alteration in the coagulation pathway which predisposes to thrombus. Usually genetic or acquired.
What are three possible mechanisms of genetic hyper-coagulability conditions?
Factor V mutations. Cane be defects in anti-coagulation pathways e.g. Anti thrombin III deficiency. Could also be defects in fibrinolysis.
What are some high risk acquired hypercoagulable states?
MI, immobilisation, tissue damage, cancer, prosthetic heart valves, DIC, hepatic induced thrombocytopaenia and antiphospholipid syndrome.
What are some low risk acquired hypercoagulability states?
AF, cardiomyopathy, nephrotic syndrome, oral contraceptives, late pregnancy, sickle cell anaemia and smoking.
What are two types of blood flow disruptions?
Turbulence and stasis?
What are the results of disruption of laminar blood flow?
Platelets come into contact with epithelium. Clotting factors not diluted by normal blood flow. Inform of anticoagulant factors is slowed allowing thrombi to persist. Endothelial activation is promoted.
What situations can lead to turbulence and stasis?
Impaired venous drainage beading to DVT. Non contractile areas of myocardium following MI. Aneurysms. A fib. Mitral valve stenosis. Left atrial dilatation.
What are the different morphologies of thrombus?
Arterial, mural and venous.
What is an arterial thrombus?
Often occlude the lumen. They are associated with atheroma and have firm attachment to the wall, they show lines of Zahn.
Where are common sites for arterial thrombi?
Coronary, femoral and cerebral.
Where do we get mural thrombi?
Ventricles (heart) and aortic aneurysms.
What can a mural embolism of the heart cause?
MI’s and arrhythmias.
What is the appearance of mural thrombi and why?
Look laminated due to alternating light and dark bands.
Light - platelet and fibrin.
Dark - RbC and wbc bands.
These are called lines of Zahn.
What are venous thrombosis otherwise called?
Plebothomboses.
What blood flow are venous thrombosis often related to?
Stasis.
What is the appearance of venous thrombi?
Reddish blue and form casts which are adherent to the walls.
What are the most common venous thrombi?
Popliteal, femoral, iliac and pelvic.
What is probably the most important venous thrombi?
DVT of the calf.
What are four fates of thrombi?
Proximal propagation - small to large vessel.
Embolisation resolution - fibrinolysis.
Organisation - granulation tissue
DIC.
What is an embolism?
Detached intra vascular solid, liquid or gaseous mass, carried by the bloodstream to a site distant from the point of origin.
99% are thromboemboli.
What different types of emboli are there?
Thrombo, fat, marrow, air, septic, amniotic and tumour.
Where do 95% of pulmonary thromboembolisms come from?
95% from large leg veins e.g. Popliteal , iliac and femoral.
How do DVT in the leg travel to the lungs?
Via the IVC.
What do pulmonary infarcts look like?
They are wedge shaped and firm.