Pathophysiology of Thrombosis and Embolism

Question 1

What is the characteristic of normal blood flow?

Answer 1

Laminar

Question 2

What contributes to bloods laminar flow?

Answer 2

• Pressure gradient
• Resistance
• Viscosity of blood
• Velocity
• Compliance

Question 3

Stasis

Answer 3

Stagnation of flow

Question 4

Turbulence

Answer 4

Forceful, unpredictable flow

Question 5

Defects in blood flow

Answer 5

• Thromboembolism
• Atheroma
• Hyperviscocity
• Spasm
• External compression
• Vasculitis
• Vascular steal

Question 6

What are the 3 components of Virchow’s triad?

Answer 6

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

Question 7

What is Virchow’s triad?

Answer 7

Factors causing thrombosis

Question 8

Thrombus

Answer 8

• Formation of a solid mass from the constituents of blood within the vascular system during life
• Caused by Virchow’s triad

Question 9

Give an example of a change in a vessel wall.

Answer 9

Atheromatous coronary artery

Question 10

How does Virchow’s triad influence the pathogenesis of thrombosis?

Answer 10

• Endothelial injury
• Stasi or turbulent blood flow
• Hypercoagulability of the blood

Question 11

Pathogenesis of thrombosis

Answer 11

• Atheromatous coronary artery
• Turbulent blood flow
• Loss of intimal cells, denuded plaque
• Collagen exposed, platelets adhere
• Fibrin meshwork, RBCs trapped
• Alternating bands: lines of Zahn
• Further turbulence an platelet deposition
• Propagation
• Consequences

Question 12

What is the relationship between atheroma and thrombosis?

Answer 12

Arterial thrombosis most commonly superimposed on atheroma

Question 13

How is hypercholesterolemia related to Virchow’s triad?

Answer 13

Change in blood constituents

Question 14

How does flow vary across the thrombus?

Answer 14

Turbulent flow is greatest at the end of the thrombus

Question 15

Give 2 examples of changes to blood constituents.

Answer 15

• Hyperviscosity

- Post traumatic hypercoagulability

Question 16

What can cause stasis?

Answer 16

• Post-op

- Economy class syndrome

Question 17

What can cause turbulence?

Answer 17

• Atheromatous plaque

- Aortic aneurysm

Question 18

What do consequences of thrombosis depends on?

Answer 18

• Site
• Extent
• Collateral circulation

Question 19

What are common clinical scenarios related to thrombosis?

Answer 19

• DVT
• Ischaemic limb
• MI

Question 20

What are the possible outcomes of thrombosis?

Answer 20

• Resolution
• Organisation/ recanalization
• Death
• Propagation leading to embolism

Question 21

Embolism

Answer 21

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

Question 22

Embolus

Answer 22

Detached intravascular solid, liquid or gaseous mass

Question 23

What are most emboli?

Answer 23

Dislodged thrombi

Question 24

What do factors causing embolism depend on?

Answer 24

Type of embolus

Question 25

What are the possible sources of a systemic/arterial thromboembolus?

Answer 25

- Mural thrombus - Aortic aneurysms - Atheromatous plaques - Valvular vegetations

Question 26

What are mural thrombi associated with?

Answer 26

- MI | - Left atrial dilatation and AF

Question 27

Where do thromboembolism travel to?

Answer 27

Travel to wide variety of sites: - Lower limbs most common - Brain - Other organs

Question 28

What do consequences to systemic thromboembolism depend on?

Answer 28

- Vulnerability of affected tissues - Ischaemia calibre of occluded vessels - Collateral circulation - Usually infarction occurs

Question 29

Where do venous thromboembolus originate from?

Answer 29

Deep venous thrombosis (lower limbs)

Question 30

What is the most common form of thromboembolic disease?

Answer 30

DVT

Question 31

Where does DVT travel to?

Answer 31

Pulmonary arterial cicrulation

Question 32

What may DVT occlude?

Answer 32

Dependent on size: - Main pulmonary artery - Bifurcation - Smaller arteries

Question 33

What are the possible consequences of DVT?

Answer 33

- Silent - Pulmonary haemorrhage/infarction - Right heart failure - Sudden death

Question 34

What do multiple PEs over time lead to?

Answer 34

- Pulmonary hypertension | - Right ventricular failure

Question 35

What are consequences of thromboembolism dependent on/

Answer 35

Size of embolus

Question 36

What are the risk factors for DVT and pulmonary thromboembolism?

Answer 36

- Cardiac failure - Severe trauma/burns - Post-op/post-partum - Nephrotic syndrome - Disseminated malignancy - Oral contraceptive - Increased age - Bed rest/ immobilisation - Obesity - PMH of DVT

Question 37

What is the prophylaxis for surgical patients at risk?

Answer 37

- TEDS | - s/c heparin

Question 38

When do fat embolus occur?

Answer 38

After major fractures

Question 39

What is affected by fat embolisms?

Answer 39

- Brain - Kidneys - Skin

Question 40

What can gas embolisms cause?

Answer 40

Decompression sickness

Question 41

How do gas embolisms occur?

Answer 41

N2 forms as bubbles which lodge in capillaries

Question 42

How can air embolisms enter the body?

Answer 42

- Head and neck wounds - Surgery - CV lines

Question 43

How can tumours cause embolisms?

Answer 43

Spread of the tumour

Question 44

Who do trophoblast tumours affect?

Answer 44

Pregnant women

Question 45

What is affected by trophoblast embolisms?

Answer 45

Lungs

Question 46

Give an example of a condition which can result in septic material forming an embolism?

Answer 46

Infective endocarditis

Question 47

What are amniotic fluid embolism the cause of?

Answer 47

Collapse +/- death in childbirth

Question 48

How are bone marrow embolisms formed?

Answer 48

- Fractures | - CPR

Question 49

How are foreign body embolisms formed?

Answer 49

- Intravascualr cannulae tips | - Sutures

Question 50

Types of embolisms

Answer 50

- Amniotic fluid - Bone marrow - Foreign bodies - Tumour - Trophoblast - Septic material - Gas - Air embolus - Fat - Venous thromboembolism - Systemic/ arterial thromboembolism