Lect 13 - Atheroma, Thrombosis & Embolism

Question 1

what is Atherosclerosis

Answer 1

“Degeneration of arterial walls characterised by fibrosis, lipid deposition and inflammation which limits blood circulation and predisposes to thrombosis”

Question 2

what vessels are commonly affected by Atherosclerosis

Answer 2

Bifurcations (sites of turbulent flow)
Abdominal aorta 
Coronary arteries
Popliteal arteries
Carotid vessels
Circle of Willis

Question 3

What are the common nonmodifiable risk factors for Atherosclerosis

Answer 3

Age
Male
FH
Genetic

Question 4

what are the modifiable risk factors for atherosclerosis?

Answer 4

Hyperlipidaemia (LDL:HDL)
Hypertension
Smoking
Diabetes

Question 5

talk though the Pathophysiology of Atherosclerosis formation, up to the point of fatty streak formation.

Answer 5

endothelial injury -> lipid accumulates in intima ->Monocytes come and ingest the lipid becoming foam cells

FORMS FATTY STREAK

Question 6

what do foam cells do?

Answer 6

secrete chemokines attracting more monocytes/macrophages, lymphocytes and smooth muscle cells

CONSTITUENTS OF THE ATHEROSCLEROTIC PLAQUE

Question 7

What different zones within the plaque form?

Answer 7

the edges = “shoulders”
the top = “fibrous cap”
the middle = “necrotic core”

Question 8

what tends to happen after atherosclerosis formation?

Answer 8

Occlusion

Weakening of vessel walls
Aneurysm formation

Erosion
Thrombosis formation?

Question 9

what is a Thrombosis

Answer 9

Solidification of blood contents formed in the vessel during life.

it is different to a clot in pathogenesis and morphology.

Question 10

what factors make up virchow’s triad

Answer 10

The intimal surface of the vessel
The pattern of blood flow
Blood constituents

Question 11

what are platelets fragments of?

Answer 11

Fragments of megakaryocytes in the bone marrow

Question 12

what do Platelets release?

Answer 12

Alpha granules: fibrinogen, fibronectin, PDGF

Dense granules: chemotactic chemicals

Question 13

why would plaque rupture lead to arterial thrombus?

Answer 13

causes turbulent flow and intimal change. also Hyperlipidaemia – change in blood constituents

Platelets bind and fibrin is produced entrapping RBC

Question 14

what is Venous thrombosis caused by?

Answer 14

Intimal change: valves

Change in blood flow: Immobile

Change in blood constituents:
Inflammatory mediators (infection, malignancy)
factor V leiden
Oestrogen

Question 15

what is a thrombi in the heart known as?

Answer 15

mural thrombi

Question 16

where do mural thrombi form?

Answer 16

over areas of endomyocardial injury:
MI
Myocarditis

NOTE : Can also occur with arrhythmias and cardiomyopathy

Question 17

what is the major risk of thrombosis?

Answer 17

Embolisation

Question 18

what is an Embolus

Answer 18

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

Question 19

what is the most common type of emboli?

Answer 19

PE.

Very common cause of hospital morbidity and mortality

Question 20

what are the clinical effects of a small PE

Answer 20

initially asymptomatic, if multiple may result in pulmonary hypertension

Question 21

what are the clinical effects of a medium PE

Answer 21

Cause acute respiratory and cardiac failure (V/Q mismatch, RV strain)

Question 22

what are the clinical effects of a large (saddle) PE

Answer 22

Death

Question 23

what are the types of emboli? (6)

Answer 23

infective
tumour
gas
Amniotic fluid embolism
Fat embolism
Foreign body embolism

Question 24

where do Infective emboli come from?

Answer 24

Usually from the vegetations on infected heart valves

Effects compounded by the infective nature – may lead to mycotic aneurysm formation

Question 25

where do Tumour emboli come from?

Answer 25

Bits may break off as tumours penetrate vessels Do not usually cause immediate physical problems

Question 26

where do Gas emboli come from?

Answer 26

Air (vessel opened into the air) ``` Nitrogen Decompression sickness (“the bends”) ```

Question 27

where do Amniotic fluid emboli come from?

Answer 27

Increased uterine pressure during labour may force AF into maternal uterine veins (1:50,000 deliveries)

Question 28

where do fat emboli come from?

Answer 28

Microscopic fat emboli found in 80% patients with significant trauma at PM Sudden onset of respiratory distress

Question 29

where do foreign body emboli come from?

Answer 29

Particles injected intravenously E.g. talc in IVDU’s Leads to a granulomatous reaction