pathophysiology of thrombosis and embolism

Question 1

what are the two types of abnormal blood flow?

Answer 1

stasis

turbulent

Question 2

what is static blood flow?

Answer 2

stagnation of flow

Question 3

what is turbulent blood flow?

Answer 3

unpredictable and forceful

Question 4

what are the causes of abnormal blood flow?

Answer 4

thromboembolism
atheroma
hyoerviscosity
spasm
external compression
vsculitis
vacsular steal

Question 5

what can cause external compression of blood vessels causing abnormal flow?

Answer 5

a tumour pressing on the vessel

baby pressing on vessels during pregnancy

Question 6

what is vascular steal?

Answer 6

dilation of one vascular network (e.g., during exercise or vasodilator therapy) “steals” blood flow from another region within the organ that is already maximally dilated because of the presence of proximal lesions.

Question 7

what is Virchow’s triad of the factors causing thrombosis?

Answer 7

• Changes in the blood vessel wall
• Changes in the blood constituents
• Changes in the pattern of blood flow

Question 8

what is the difference between a thrombus and a clot?

Answer 8

a thrombus forms within the vascular system during life.

A clot can occur anywhere and postmortem in the vascular system it is called a clot

Question 9

give an example of a change in vessel wall that can increase the risk of thrombosis?

Answer 9

atheromatous plaque in artery

Question 10

give an example of three typical changes which lead to thrombosis?

Answer 10

endothelial injury
stasis or turbulent blood flow
hypercoagulability of blood

Question 11

what are line’s of Zahn?

Answer 11

alternating bands of red blood cells and platelets with fibrin

Question 12

give a detailed description of the pathogenesis of thrombosis, starting with an atheromatous coronary artery

Answer 12

1. atheromatous coronary artery
2. turbulent flow
3. loss of intimal cells from denudation of the plaque
4. platelets adhere to exposed collagen
5. fibrin network forms and RBCs trapped
6. lines of Zahn appear
7. further turbulence and platelet deposition
8. leads to propagation

Question 13

what can cause changes in vessel wall that leads to thrombosis?

Answer 13

• myocardial infaction- can lead to mural thrombosis in the heart
• turbulent flow- denuding intima

Question 14

what is a mural thrombosis?

Answer 14

blood clot on the wall of the heart

Question 15

what factors can lead to changes in blood viscosity, leading to increased risk of thrombosis?

Answer 15

polycythaemia, dehydrated, post-traumatic hypercoagulability

Question 16

what can lead to stasis of blood flow and then thrombosis?

Answer 16

• long flights sitting down

- post operation (bed-bound)

Question 17

what can cause turbulence of flow which can lead to thrombosis?

Answer 17

atheromatous plaque

aortic aneurysm

Question 18

what three things do the consequences of a thrombosis depend on?

Answer 18

site
extent
collateral circulation

Question 19

what are the favourable outcomes of thrombosis?

Answer 19

• resolution

- organisation and recanalisation

Question 20

what are the unfavourable outcomes of thrombosis?

Answer 20

death

propagation leading to embolism

Question 21

what is embolism?

Answer 21

Movement of abnormal material in the bloodstream and its impaction in a vessel, blocking its lumen

Question 22

what are some of the sources of thrombi in the arterial system?

Answer 22

• mural thrombus
• aortic aneurysm
• atheromatous plaques
• valvular vegetations

Question 23

what is a paradoxical emboli?

Answer 23

an embolus from a thrombus in the arterial system but has causes a pulmonary embolism (usually associated with venous thrombosis). This occurs as a result of a septal defect in the heart.

Question 24

what can cause mural thrombus?

Answer 24

• MI

- left atrial dilatation and atrial fibrilation

Question 25

what are valvular vegetations?

Answer 25

growths on the valves of the heart often associated with endocarditis

Question 26

which sites are common for arterial emboli to get lodged in?

Answer 26

lower limbs
brain
other organs

Question 27

the vulnerability of tissues to infarction following embolism depends on what factors?

Answer 27

• vulnerability of affected tissue to ischaemia
• calibre of affected vessel
• collateral circulation

Question 28

where do venous thrombi embolise to?

Answer 28

the pulmonary circulation

Question 29

what do the consequences of a pulmonary embolus depend on?

Answer 29

the size of the embolus. which determines the size of the artery it gets lodged in

Question 30

what can occur if multiple pulmonary emboli occur over time?

Answer 30

pulmonary hypertension and right ventricular failure

Question 31

what is a silent pulmonary embolus?

Answer 31

a pulmonary embolism with no clinical symptoms

Question 32

what are the severe consequences of pulmonary embolism?

Answer 32

• pulmonary haemorrhage/ infarction
• right heart failure
• sudden death

Question 33

what are the risk factors for deep venous thrombosis?

Answer 33

• Cardiac failure
• severe trauma/burns
• post-op/post-partum (after childbirth)
• nephrotic syndrome
• disseminated malignancy
• oral contraceptive
• increased age
• bed rest/immobilisation
• obesity
• PMH of DVT

Question 34

when are patients at risk if fat embolism?

Answer 34

after major fractures

Question 35

which parts of the body are usually affected by fat embolism?

Answer 35

brain, kidneys, skin

therefore it can be syndrome

Question 36

when can gas embolus (of nitrogen) occur?

Answer 36

in decompressoin sickness (divers come up to the surface too quickley)

Question 37

when can an air embolus occur?

Answer 37

head and neck wounds
surgey
central venous lines (catheters)

Question 38

what is a trophoblast embolism?

Answer 38

material from the placenta dislodges and enters the maternal blood stream

Question 39

when can a tumour cause an embolism?

Answer 39

part of the tumour detaches and spreads to another part of the body (metastasises)

Question 40

when can septic material cause an embolism?

Answer 40

when some septic material breaks off from an infected tissue. eg. an infective endocarditis

Question 41

what sort of embolism can occur in childbirth?

Answer 41

amniotic fluid embolism

Question 42

what sort of embolism can occur as a result of fractures (and CPR)?

Answer 42

bone marrow embolism

Question 43

when can embolisms occurefrom foreign bodies?

Answer 43

from medical intervention. eg. cannulae tips and sutures

Question 44

what is rheumatic fever?

Answer 44

it is a disease of disordered immunity that occurs following the infection of a group A beta haemolytic streptococcus. It causes inflammatory changes in the heart and joints, sometimes with neurological symptoms

Question 45

what are the presenting features of rheumatic fever?

Answer 45

flitting, painful polyarthritis of large joints
plus skin rashes and fever
recent sore through due to infectin

Question 46

what inflammatory bodies form in the heart in rheumatic fever?

Answer 46

aschoff body

Question 47

how does rheumatic fever affect the valves of the heart?

Answer 47

valvular stenosis
valvular regurgitation
vegetations- impair mobility

Question 48

what is pacarditis and in what stage of rheumatic fever does in occur?

Answer 48

inflammation of the endocardium, myocardium and pericardium. it occure in the acute phase

Question 49

what is rheumatic heart disease?

Answer 49

acute rheumatic fever can progress over time to chronic rheumatic heart disease, mainly manifesting as valvular abnormalities. and characterised principally by deforming fibrotic valvular disease

Question 50

which valves are affected by rheumatic heart disease?

Answer 50

mitral valve- stenosis and regurgitaion
aortic-stenosis (rarely) and regurgitation
tricuspid and pulmonary valve involvement rare.

Question 51

what is the most common cause of aortic stenosis?

Answer 51

aortic calcification valve disease

Question 52

what is the most common cause of mitral regurgitation?

Answer 52

ischaemic heart disease

Question 53

how does rheumatic heart disease affect the mitral valve?

Answer 53

typically leaflet thickening, commissural fusion and shortening, thickening and fusion of chordae tendineae