Atheroma, Thrombosis and Ebolism

Question 1

What is atherosclerosis?

Answer 1

Degeneration of arterial wall characterised by fibrosis, lipid deposition and inflammation.
-limits blood circulation and predisposes thrombosis.

Question 2

What are the commonly affected vessels of atherosclerosis?

Answer 2

• Bifurcations
• Abdominal aorta
• Coronary arteries
• Popliteal arteries
• Carotid vessels
• Circle of Willis

Question 3

What are the non-modifiable risk factors of atherosclerosis? (4)

Answer 3

• Age
• Male
• FH
• Genetic

Question 4

What are the modifiable risk factors of atherosclerosis? (5)

Answer 4

• Hyperlipidaemia
• Hypertension
• Smoking
• Diabetes
• CRP

Question 5

Why does atherosclerosis arise?

Answer 5

Due to chronic injury and repair of the endothelium.

-1st step = endothelial injury

Question 6

What are the main causes of atherosclerosis? (4)

Answer 6

• Haemodynamic injury
• Chemicals
• Immune complex deposition
• Irradiation

Question 7

Describe the process of atheroma formation.

Answer 7

• Hyperlipidaemia and endothelial injury&raquo_space; lipid accumulation in intima
• Monocytes ingest the lipid&raquo_space; foams cells (fatty streak)
• Foam cells secrete chemokines&raquo_space; attract more monocytes/lymphocytes/smooth muscles cells
• Forms ATHEROSCLEROTIC PLAQUE

Question 8

What is the structure of an atheromatous plaque?

Answer 8

• Fibrous cap (superficially)
• Necrotic centre
• Media (deep)

Question 9

What is the fibrous cap of an atheromatous plaque composed of? (4)

Answer 9

• Smooth muscle cells
• Macrophages
• Foam cells
• Collagen

Question 10

What is the necrotic centre of an atheromatous plaque composed of? (4)

Answer 10

• Cell debris
• Cholesterol
• Foam cells
• Calcium

Question 11

What is thrombosis?

Answer 11

Solidification of blood contents in the vessel during life.

Question 12

How is thrombosis different to a clot? (3)

Answer 12

• Thrombosis is during life, clot is stagnant blood
• Thrombosis is dependent on platelets, clots are enzymatic processes
• Thrombosis is firm, clots are elastic/adopt shape of the vessel

Question 13

What are platelets?

Answer 13

Fragments of megakaryocytes in the bone marrow.

-circulate in the blood and help form clots

Question 14

How are platelets activated?

Answer 14

They bind to collagen exposed by endothelial damage&raquo_space; activation.

Question 15

What do activated platelets secrete? (2)

Answer 15

• Alpha granules; fibrinogen, fibronectin, PDGF

- Dense granules; chemotactic chemicals

Question 16

What is Virchow’s triad?

Answer 16

The 3 factors required for thrombosis;

• intimal surface of vessel
• blood flow (stasis/turbulence)
• blood constituents (mediators)

Question 17

How does an arterial thrombus form?

Answer 17

-Turbulence
>> loss of endothelial cells
>> exposure of collagen
>> platelet adherence and activation
>> THROMBUS FORMATION

Question 18

What are the lines of Zahn?

Answer 18

Rib-like markings characteristic of thrombi near the heart or aorta.

Question 19

What factors contribute to venous thrombosis? (3)

Answer 19

• Intimal changes; valves
• Change in blood flow; immobile
• Change in blood constituents; mediators/FV leiden/oestrogen

Question 20

What are cardiac thrombi known as?

Answer 20

Mural thrombi.

-occur over areas of endomyocardial injury

Question 21

What are the main causes of cardiac thrombi? (4)

Answer 21

• MI
• Myocarditis
• Arrhythmias
• Cardiomyopathy

Question 22

What is the general sequence of embolism formation?

Answer 22

Occlusion of vessel (thrombus)
>> resolution
>> incorporation into vessel wall
>> recanalisation
>> embolisation

Question 23

What is an embolus?

Answer 23

A mass of material in the vascular system able to lodge in a vessel and block it.

Question 24

What are the different types of emboli?

Answer 24

• Exogenous/endogenous

- Solid/liquid/gas

Question 25

What is the most common emboli?

Answer 25

Pulmonary embolism.

Question 26

What are the main risk factors for venous thromboembolism (VTE)?

Answer 26

ACQUIRED - immobility, malignancy, heart failure. oestrogens, obesity, pregnancy
GENETIC - thrombotic disorders

Question 27

Name 2 genetic disorders that are risk factors for venous thromboembolism.

Answer 27

• Factor V leiden

- Protein S deficiency

Question 28

What are the clinical effects of venous emboli?

Answer 28

SMALL - usually asymptomatic
MEDIUM - acute respiratory and cardiac failure
LARGE - death (‘saddle emboli’)

Question 29

Where do systemic emboli arise? (2)

Answer 29

• Heart (MI/AF)

- Arterial circulation (atheroma)

Question 30

Where do systemic emboli always travel to?

Answer 30

The lungs.

-pulmonary emboli

Question 31

What do infective emboli usually form from?

Answer 31

Vegetations on infected heart valves.

Question 32

What can infective emboli lead to?

Answer 32

Mycotic aneurysm formation.

Question 33

How do tumour emboli form?

Answer 33

Bits may break off a tumour as they penetrate vessels.

Question 34

Do tumour emboil usually cause immediate physical problems?

Answer 34

No.

Question 35

What are the main forms of gas emboli?

Answer 35

• Air

- Nitrogen

Question 36

How does air get into vessels to form gas emboli?

Answer 36

Obstetric procedures/chest wall injury.

->100ml to cause clinical effects

Question 37

How does nitrogen get into vessels to form gas emboli?

Answer 37

Decompression sickness.

• divers/tunnel workers
• enter bones/joints/lungs

Question 38

How do amniotic fluid emboli form?

Answer 38

Increased uterine pressure during labour&raquo_space; AF may enter maternal uterine veins
-can lodge in lung&raquo_space; respiratory distress

Question 39

How many patients with significant trauma are found to have fat emboli at post-mortem?

Answer 39

~80%.

Question 40

What do far emboli cause?

Answer 40

Sudden onset of respiratory distress.

Question 41

How do foreign body emboli often form?

Answer 41

Particles injected intravenously.

-e.g. talc in IVDUs&raquo_space; granulomatous reaction