Thrombosis And Embolism Flashcards
What is thrombosis?
The formation of a solid mass of blood (thrombus) within the circulatory system.
How is a thrombus formed?
Virchow’s Triad, occurs when there is an abnormality in: Vessel wall, blood flow, blood components.
Describe problems with blood flow.
Stasis- narrowing, immobility, low blood pressure. Turbulent blood flow- defects in walls and heart valves, atrial fibrillation, area of dead cardiac muscle.
Describe appearance of an arterial thrombus.
Pale, granular, lower cell count, lines of Zahn.
Describe appearance of a venous thrombus.
Soft, gelatinous, deep red, higher cell count
What are the outcomes/complications of thrombosis?
Lysis, propagate, organise, recanalise, embolise.
Describe lysis.
Most likely when thrombi are small, complete dissolution of thrombus, fibrinolytic system active, blood flow re-established.
Describe propagation.
Progressive spread of thrombosis, distally in arteries and proximal veins.
Describe organisation.
Reparative process, ingrowth of fibroblasts and capillaries, lumen remains obstructed.
Describe recanalisation.
One or more channels form through area of organising thrombus. Blood flow can be re-established but usually incompletely.
Describe embolism.
Part of thrombus breaks off, travels through blood stream and lodges at a distant, secondary site.
What are effects of venous thrombosis on tissue?
Congestion, oedema, ischaemia, infarction.
What are the effects of arterial thrombosis on tissue?
Ischaemia, infarction -> depends on site and collateral circulation.
What is an embolism?
A blockage of a blood vessel by solid, liquid or gas at a site distant from its origin. >90% of emboli are thrombo-emboli.
Where can thrombosis arise?
Veins- deep vein thrombosis. Heart- MI, atrial fibrillation. Carotid artery- cerebral ischaemia. Abdominal aorta- actue limb ischaemia.
