Pathophysiology of Thrombosis and Embolism Flashcards Preview

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Flashcards in Pathophysiology of Thrombosis and Embolism Deck (33)
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1

What defects in blood flow can result in thrombosis and embolism?

Atheroma
Hyperviscosity
Spasm
External compression
Vasculitis
Vascular steal syndrome

2

What is normal blood flow?

Laminar - smooth and ordered

3

What is the vascular system affected by?

Pressure gradient
Resistance
Blood viscosity
Compliance of the vessel

4

What features of blood flow are abnormal?

Stasis
Turbulence

5

What is stasis of blood flow?

Stagnation of blood flow e.g. in cardiac failure where there is not enough force to push the blood

6

What is turbulence of blood flow?

Forceful, unpredictable flow e.g. due to something protruding into the lumen such as an atheromatous plaque
Noisy on auscultation

7

What are the components of Virchow's triad?

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

8

What is the most important risk factor for thrombus formation?

Hypercholesterolaemia

9

What is thrombosis?

Formation of a solid mass from the constituents of blood within the vascular system during life

10

What steps are involved in the pathogenesis of thrombosis?

Endothelial injury
Stasis or turbulent flow
Hypercoagulability of the blood

11

What effect does an atheromatous plaque have on blood flow when it starts to protrude from the lumen?

Starts to cause turbulent flow

12

What does turbulent blood flow cause?

Damage to the endothelial surface - loss of intimal cells and denuded plaque

13

What happens when the endothelial surface is lost due to turbulent flow?

Collagen in the fatty core of the plaque is exposed to the blood, platelets in the blood then stick to the collagen and form a fibrin meshwork which traps the RBCs

14

What do alternating bands of fibrin and RBCs form?

Lines of Zahn

15

What do the consequences of thrombosis depend on?

Site
Extent
Collateral circulation

16

What are common consequences of thrombosis?

DVT
Ischaemic limb
MI

17

What are possible outcomes of thrombosis?

Resolution
Organisation/recanalisation
May relieve itself but often medical intervention is needed to break down the platelets and restore blood flow

18

What will organisation/recanalisation cause?

Restoration of blood flow, but tissue damage may still occur as thrombus is stabilised, endothelial surface grows and fibrosis and granulation can occur along with the formation of new blood vessels

19

What is embolism?

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

20

What substances can form an embolus?

Detached intravascular solid, liquid or gaseous mass

21

What are most emboli formed from?

Detached thrombi

22

What are some causes of thromboembolism?

Systemic/arterial thromboembolism
Mural thrombus
Aortic aneurysm
Atheromatous plaque
Valvular vegetations

23

What are the features of a systemic thromboembolism?

Travels to a wide variety of sites - lower limbs most common but brain and other organs also affected
Usually infarction occurs

24

What do the consequences of a systemic thromboembolism depend on?

Vulnerability of the affected tissues to ischaemia
Calibre of occluded vessel
Collateral circulation

25

Where do most venous thromboembolisms originate from?

Deep venous thromboses in the lower limbs

26

What is the most common form of thromboembolic disease?

Venous thromboembolism

27

Where do venous thromboembolisms travel to? What can this cause?

Pulmonary arterial circulation
May occlude the main pulmonary artery, bifurcation or small arteries

28

What do the consequences of a venous thromboembolism depend on?

Size of the embolus

29

What are the potential consequences of venous thromboembolism?

May be silent
Pulmonary haemorrhage
Pulmonary infarction
Right heart failure
Sudden death

30

What do multiple pulmonary emboli cause over time?

Pulmonary hypertension and right ventricular failure