Pathophysiology of Thrombosis and Embolism

Question 1

What is an atheroma that has ruptured and formed a clot known as?

Answer 1

• Complicated atheroma

Question 2

What is normal blood flow said to be?

Answer 2

Laminar

Question 3

What does laminar blood flow mean?

Answer 3

• Blood cells travel through the middle of the vessel - Plasma travels along the sides - All constituents of the fluid travel at the same speed

Question 4

What is stasis blood flow?

Answer 4

An abnormal flow where the blood becomes stagnant

Question 5

What is turbulent blood flow?

Answer 5

• Loss of laminar flow causing “whirpooling” - Forceful and unpredictable

Question 6

What is Virchow’s triad?

Answer 6

If one of them change then vascular disease can occur

Question 7

What are the three aspects of Virchow’s triad?

Answer 7

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

Question 8

What can arise from Virchow’s triad being altered?

Answer 8

• Thrombosis

Question 9

What is the difference between thrombosis and clot?

Answer 9

• Thrombosis occurs in the body during life - Clot occurs either outside the body or during death

Question 10

Give an example of changes in the blood vessel wall that can lead to thrombosis

Answer 10

Atheromatous coronary artery

Question 11

What are the constituents of the normal arterial wall?

Answer 11

• Tunica intima - Tunica media - Tunica adventitia

Question 12

What is the pathogenesis of thrombosis?

Answer 12

• Endothelial injury - Stasis or turbulent blood flow - Hypercoagulability of the blood These three are virchow’s triad

Question 14

Study the atheroma pathology diagram

Answer 14

Question 15

What is the order of pathology of a thrombus?

Answer 15

• Atheromatous coronary artery
• Causes turbulent blood flow leading to fibrin deposition and platelet clumping
• Intimal cells lost
• Collagen below intima is exposed, platelets activated and adhere
• Further turbelence and more platelet deposition
• Propegation occurs and thrombus breaks off becoming an embolus

Question 16

How does hypercholesterolaemia follow Virchow’s triad in leaving to a thrombus

Answer 16

• Thrombus usually superimposed on atheroma after blood vessel wall is altered

Question 17

Histologically, how are thrombi laid down?

Answer 17

• Lines of Zhan
• Platelets below fibrin below RBCs etc

Question 18

What are examples of changes in the blood constituents that may lead to thrombus?

Answer 18

• Hyperviscosity
• Post traumatic hypercoagulability

Question 19

When can stasis of blood flow occur?

Answer 19

• On long haul flights without movement
• Post operative

Question 20

What conditions can lead to turbulent flow?

Answer 20

• Atheromatous plaque
• Aortic aneurysm

Question 21

What are the depending factors on the consequences of a thrombosis?

Answer 21

• Site
• Extent
• Collateral circulation

Question 22

What are the outcomes of a thrombosis?

Answer 22

• Resolution
• Complication
• Death

Question 23

What is meant by the resolution of a thrombus?

Answer 23

• Orginisation/recanalisation of the vessel occurs

Question 24

What typically causes death from a thrombus?

Answer 24

• If it becomes an embolism and moves to a vital organ

Question 25

What is the definition of an embolism?

Answer 25

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

Question 26

What can cause an embolus?

Answer 26

- Any intravascular solid liquid or gas

Question 27

What are emboli from thrombi known as?

Answer 27

Thromboembolism

Question 28

What are the common sources of ARTERIAL thromboembolus?

Answer 28

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

Question 29

What is associated with a mural thrombus

Answer 29

- MI - Left atrial dilatation - AF

Question 30

What are the common areas of spread of a thromboembolus?

Answer 30

- Lower limbs - Brain - Other organs with high blood demand

Question 31

What do consequences of an embolus depend on?

Answer 31

- Vulnerability of tissue it's lodged in to ichaemia - Size of occluded vessel and how high up it is (collateral circulation)

Question 32

What usually occurs as a result of a lodged thromoembolus?

Answer 32

Infarction

Question 33

Where do venous thromboemboli originate from

Answer 33

DVT's

Question 34

Where do venous thromboemboli travel to?

Answer 34

- Pulmonary arterial circulation - May occlude pulmonary artery

Question 35

What type of embolus occludes the bifurcation of the pulmonary artery

Answer 35

Saddle embolus

Question 36

What do the consequences of a PE rely on?

Answer 36

Size of embolus

Question 37

What types of PE's are there?

Answer 37

- Silent (asymptomatic) - Pulmonary haemorrhage/infarction - right heart failure - Sudden death

Question 38

What occurs from multiple PE's over time?

Answer 38

- Pulmonary hypertension - RV failure

Question 39

What are the risk factors for a venous thromboembolism?

Answer 39

- Cardiac failure - Severe trauma - Post op - Nephrotic syndrome - Contraceptive pill - Old age - Bed rest - Obesity - PMH of DVT

Question 40

When do fat emboli occur most commonly?

Answer 40

After major fractures

Question 41

What is an example of a gas emboli causing condition?

Answer 41

Decompression sickness - N2 forms as bubbles which lodge in capillaries

Question 42

When do air emboli most commonly occur?

Answer 42

- Head and neck wounds - Surgery - CV lines

Question 43

What type of emboli can be a result of pregnancy?

Answer 43

- Trophoblast embolus

Question 44

During what condition can septic material act as an embolus?

Answer 44

- Infective endocarditis

Question 45

What other types of rare embolus are there?

Answer 45

- Amniotic fluid - Bone marrow - Foreign bodies - Tumour