13. Thrombosis, embolism, DIC

Question 1

Define thrombus

Answer 1

A mass that is formed by the constituents of the coagulation system within blood vessels or heart. Composed mostly of numerous platelets and red blood cells trapped in a mesh of an insoluble protein called fibrin.

Question 2

What do endothelial cells posses?

Answer 2

Anti-thrombotic qualities

-synthesise prostacyclin and nitric oxide which cause vasodilation and inhibit platlet aggregation

Question 3

What happens when endothelial cells are activated?

Answer 3

Secrete or express prothrombotic substances

Question 4

What do platelets do when they become active?

Answer 4

When activated they become sticky by increasing the expression of cell surface receptors

Question 5

What is the coagulation cascade?

Answer 5

Complex interaction of proteins resulting in the formation of an insoluble protein called fibrin

Question 6

Where are the precursor forms of fibrin synthesised?

Answer 6

In the liver

Question 7

What is the intrinsic coagulation cascade?

Answer 7

Activation requires local damage to the endothelial surface of a blood vessel

Question 8

What is the extrinsic pathway of the coagulation cascade?

Answer 8

Activation requires tissue injury

Starts from blood vessel injury and release of tissue factor

Question 9

Describe the morphology of a thrombus?

Answer 9

Successive deposition of platelets and fibrin

Appears as alternating bands (lines of zahn)

Question 10

Where does a thrombosis occur?

Answer 10

Any vascular system, arterial in the heart, venous

Question 11

What are the three predisposing situations known as and what are they?

Answer 11

Virchows Triad
Changes in the intimal surface of the vessels
Changes in the pattern of blood flow
Changes in the blood constituents

Question 12

What are the risk factors of virchows triad?

Answer 12

Immobilisation 
Bed rest 
Surgery 
Obesity 
Hyper-coagulable blood
Pregnancy

Question 13

What are the risk factors of DVT?

Answer 13

Immobilisation 
Bed rest 
Surgery 
Obesity 
Hyper-coagulable blood
Pregnancy

Question 14

What is used to reduce and remove risk factors?

Answer 14

Elastic stockings
Early mobilisation
Anti-coagualtion

Question 15

Whats is an arterial thrombosis?

Answer 15

Sudden onset of a severe impairment of organ function such as “stroke” or “heart attack”

Question 16

What is a venous thrombosis?

Answer 16

Swelling blood clot in the lower limbs tissue

Swollen red and tender

Question 17

What is an embolism?

Answer 17

A mass of material that can move in the vascular system and become lodged in some vessel and blocks it lumen

Question 18

What do pulmonary embolisms lead to?

Answer 18

Venous thrombosis in deep leg veins

Question 19

What is the most common type of embolism?

Answer 19

Thromboembolism

Question 20

What are the sources of arterial emboli?

Answer 20

Carotid artery 
Mural thrombus - left atrium 
Endocartitis in aortic and mitral valves 
Mural thrombus - left atrium 
Aortic atherosclerosis

Question 21

What are common sites of infarction as a consequence of arterial emboli?

Answer 21

Brain 
Retina 
Heart (LV)
Spleen 
Kidney 
Small intestine 
Lower leg

Question 22

Why are plumonary embolisms the most common?

Answer 22

Most arrest at the first vascualar bed they meet (lungs)

Question 23

What are the effects of a pulmonary embolism?

Answer 23

May by small and not notice
Organise and cause minor reduction in lung function
Numerous emboli can cause marked reduction in lung function over time
Medium emboli can cause acute resp and cardiac problems
Large emboli can cause sudden death

Question 24

What is Disseminated Intravascular Coagualtion

Answer 24

Usually a life threatening condition, causes include sepsis, obstetric complication or malignancy.
Multiple thrombi throughout organs which consumes clotting factors and there is subsequently simultaneous bleeding