Endothelium, Plaque Rupture, Vascular Injury (complete)

Question 1

What are the layers of a blood vessel? Outside to inside

Answer 1

• Adventitia
• External elastic lamina
• Media
• Internal elastic lamina
• Intima

Question 2

What is in the intima?

Answer 2

• endothelium

- thin layer CT

Question 3

What is in the media?

Answer 3

• VSM

- CT

Question 4

What is in the adventitia?

Answer 4

loose CT

Question 5

Describe the differences between large arteries, smaller arteries, and arterioles (in terms of what it’s made of)

Answer 5

Large: more elastin

Smaller: more collagen

Arterioles: more SM

Question 6

Describe normal endothelial cells

Answer 6

• impermeable to large molecules
• Anti-inflammatory
• Resist leukocyte adhesion
• Promote vasodilation
• Resist thrombosis

Question 7

Describe activated endothelial cells

Answer 7

• ^ permeability
• ^ inflammatory cytokines
• ^ leukocyte adhesion molecules
• Decreased vasodilatory molecules
• decreased antithrombotic molecules

Question 8

Describe smooth muscle cells

Answer 8

• normal contractile function
• maintain ECM
• Contained in medial layer

Question 9

Describe activated smooth muscle cells

Answer 9

• ^ inflammatory cytokines
• ^ ECM synthesis
• ^ migration/proliferation into subintima

Question 10

What’s the main thing you need to know about nitric oxide?

Answer 10

it’s a vasodilator!

Question 11

What happens to NO when you activate an inflammatory state?

Answer 11

it decreases

Question 12

Describe vulnerable plaques

Answer 12

• Less fibrous tissue
• Less calcified
• More lipid content
• More inflammation
• More apoptosis

Question 13

Describe stable plaques

Answer 13

• Rich in fibrous tissue
• Calcified
• Less lipid content
• Less inflammation
• Less apoptosis

Question 14

Describe plaque rupture and how it leads to thrombosis

Answer 14

• “Stable” plaque w/ small lipid pool, thick fibrous cap, preserved lumen
• Becomes vulnerable plaque (large lipid pool, thin fibrous cap, many inflammatory cells)
• Then ruptures w/ thrombus formation
• Can either lead to acute MI
• Or become a healed rupture w/ narrowed lumen and fibrous intima (lots of occlusion)

Question 15

What are the 3 stages in the development of atherosclerotic plaque?

Answer 15

1) Fatty streak
2) Plaque progression
3) Plaque disruption

Question 16

Describe the fatty streak as a stage in the development of atherosclerotic plaque

Answer 16

• endothelial dysfunction
• Lipoprotein entry and modification
• Leukocyte recruitment
• Foam cell formation

Question 17

Describe plaque progression as a stage in the development of atherosclerotic plaque

Answer 17

• SM cell migration
• Altered matrix synthesis & degradation
• It really starts to build up

Question 18

Describe plaque disruption as a stage in the development of atherosclerotic plaque

Answer 18

• Disrupted plaque integrity
• thrombus formation

This is the thing that can lead to MI
- happens even when there is only a 50% occlusion => if the plaque is vulnerable then it can do anything!

Question 19

Describe the common mechanism of stroke

Answer 19

• Atheroembolization from carotid bifurcation lesion
• Source lesion does not need to be obstructive (<70% diameter reduction)
• Ophthalmic artery

Also:
- Thromboembolization from left atrial appendage in setting of AFib

Question 20

Describe the type types of MI

Answer 20

1: plaque ruptuse => non-occlusive thrombosis => some flow but intermittent occlusion/embolization => stabilize w/ anticoag/ vasodilators
2: Plaque rupture => occlusive thrombus => no flow => clinical emergency => recanalize

Question 21

Describe peripheral arterial disease

Answer 21

Manifestations:

• Claudication: obstructive (>70%) stable plaque
• Acute limb ischemia: acute event obstructs blood flow w/o prior development of collaterals — could be athero- or thromboemboli (rarely in-situ thrombosis)