Thrombosis, Embolism, ischaemia and infarction

Question 1

What is Virchow’s triad for thrombosis?

Answer 1

Venous stasis
Endothelial damage
Hypercoagubility

Question 2

What are the two main forms of thrombi?

Answer 2

There are arterial clots that are white and mainly formed of platelets in high flow, they can be mural or occlusive
There are venous clots that are red and consist of mainly RBCs

Question 3

Where do cardiac thrombosis most commonly occur?

Answer 3

In the atria but can occur on valve vegetations

Question 4

What are the three main stages following formation of a clot?

Answer 4

Resolution - dissolving the clot from the fibrinolytic system
Organisation - formation of granulation tissue within the clot from the ingrowth of fibroblasts and capillaries
There can be recanalisation or fibrosis

Question 5

What are the 6 factors that affect the severity of ischaemia?

Answer 5

Speed of onset
Extent of obstruction
Anatomy of local blood supply (collaterals)
Pathology of collaterals
General factors e.g. cardiac output
Vunerability of tissues to anoxia

Question 6

What are the three factors that infarctions are classified by?

Answer 6

Their shape (wedge or other)
Their colour (red or white)
Infection (bland or septic)

Question 7

What are the different histological changes tissue undergos after certain time periods?

Answer 7

Necrosis - usually coagulative - 6-12hours
Acute inflammation - Congestion, oedema, migration of polymorphs - 24 hours-7 days
Organisation - Ingrowth of capillaries, macrophages and fibroblasts - 3 days - 2 weeks
Scar formation - Deposition of collagen - 2 weeks - 3 months

Question 8

What are the two main patterns of MI?

Answer 8

Regional - from a thrombus of a main coronary artery branch

Subendocardial - from severe atheroma of multiple vessels and causes diffuse damage