11. Atheroma, Thrombosis and Embolism Flashcards Preview

EMS - Mechanisms of Disease > 11. Atheroma, Thrombosis and Embolism > Flashcards

Flashcards in 11. Atheroma, Thrombosis and Embolism Deck (23):
1

what is atherosclerosis

degeneration of arterial walls characterised by fibrosis, lipid deposition and inflammation, which limits blood circulation and predisposes to thrombosis, i.e. accumulation of fat on the vessel wall, attracts thrombosis

2

vessels which are vulnerable to atherosclerosis

aorta
coronary vessels
popliteal arteries
neck vessels
circle of willis
sites of bifurcation

3

why are areas of bifurcation at a higher risk of atherosclerosis?

thi is because they are sites of turbulent flow. Blood tends to come in contact with vessel walls here. linear flow ensures blood flows in the centre of the vessel

4

what are the risk factors for atherosclerosis?

old age
men
women after menopause
family history
hyperlipidaemia (especially LDL)
hypertension
smoking
type II diabetes
rare causes - homocysteine, stress, CRP

5

what is the pathophysiology of atherosclerosis?

1. endothelial injury - makes the vessel wall more permeable to inflammatory agents and lipids
2. fatty streak - lipid accumulates in the intimate of the vessel. prior injury also causes vessel wall to attract inflammatory cells, which will ingest the fat. won't be able to handle too much fat in them, will form foam cells
3. formation of the atherosclerotic plaque - foam cells secrete chemokines, attract more inflammatory cells and creat more permeability. also attract lymphocytes and cause smooth muscle proliferation and fibrosis at the site of accumulation

6

what is the atherosclerotic plaque made up of?

fat + extracellular material + leukocytes + smooth muscle
has a fibrous cap, shoulder, and a dead, central core

7

what are the consequences of atherosclerosis?

1. occlusion of blood supply
2. weakens vessel wall, could lead to aneurysms
3. erosion by turbulence of blood flow or leakage from shoulder leading to formation of thrombosis

8

what is thrombosis?

solidification of blood contents formed IN the vessel DURING life

9

what are the differences between a clot and a thrombus?

clot -
stagnant blood
clotting cascase
elastic, adopts vessel shape
could occur after death
thrombus
platelet dependent
firm
within the body during life

10

what are platelets?

fragments of megakaryocytic, don't contain a nucleus

11

what are the main active components of platelets?

alpha granules - contain substances required for the production of fibrin
dense granules - contain chemotactic chemicals, to attract other platelets

12

how are platelets activated?

exposure to sub endothelial collagen. this only happens when the endothelium is damaged. platelets bind to this collagen, produce fibrin and trap RBCs.

13

what are the 3 factors in virchow's triad?

1. change in the intimal surface of the vessel
2. change in the patter of blood flow
3. change in blood constituents

14

why are thrombi usually formed downstream from atheroma?

atherosclerosis causes turbulent blood flow once blood has passed by it, making it more likely to form a thrombus

15

examples of changes in constituents of blood

infection
malignancy
inherited thrombogenic factors
high levels of oestrogen (OCP, pregnancy)

16

what are the consequences of thrombi?

occludes vessels
might resolve on its own or with the help of drugs
may get incorporated into the vessel wall by fibrosis
recanalisation - new lumen forms through the thrombosis
embolisation

17

what is an embolus?

a mass of material in the vascular system that is able to lodge in a vessel and block it, it may be asymptomatic id collateral circulation is present

18

what is a common origin of a PE?

in the legs, due to pooling of blood

19

what is a paradoxical embolus?

once that forms in arteries and moves into the venous circulation due to a hole in the heart

20

what are the acquired risk factors for a DVT/PE?

immobility
malignancy
previous emboli
heart failure
high oestrogen
age
obesity
pregnancy
renal disease
smoking

21

what are the genetic factors for a DVT?

factor V leiden
protein S deficiency

22

what is the gold standard for diagnosing embolisms?

CTPA

23

what are the types of emboli?

atheromatous
platelet emboli
infective embolisms
tumour emboli
gas embolus
amniotic fluid embolism
fat embolus
foreign body embolus