Week 4 Pre-Learning: CAD + Atherosclerosis

Question 1

What is CAD? (4)

Answer 1

most common form of heart disease
- aka coronary heart disease, ischemic heart disease
- Second major cause of death in Canada
- Leading cause of hospitalization

Question 2

Why does CAD occur?

Answer 2

• Primary cause is atherosclerosis

Question 3

What is atherosclerosis?

Answer 3

• formation of fatty, fibrous plaque within the intima layer of the artery

injury of blood vessel that causes inflammation

Question 4

Is atherosclerosis always symptomatic? (2)

Answer 4

• Present in almost every human by the age of 15
• Usually asymptomatic until a vessel is 75% occluded

Question 5

What signs would you typically see with 75% occlusion? 90%?

Answer 5

70% - signs of ischemia with exertion
90% - Ischemia at rest

Question 6

What is the role of endothelium in blood vessels? (2)

Answer 6

• lines the blood vessels
• separates the blood stream from the artery wall, preventing substances from the blood from moving into the blood vessel wall

Question 7

How does atherosclerosis begin?

Answer 7

small injury to the endothelium lining

Question 8

What are the characteristics of the tunica intima of the endothelium? (4)

Answer 8

• innermost layer
• keeps blood moving through the body
• protects artery wall from coming in contact w/ toxins and substances that can cause harm
• Allow blood to form without sticking to vessel lining

Question 9

In the video, what is the role of the endothelium? (2)

Answer 9

• Produces substances that prevent blood from clotting when it should not
• If injury to these cells, cytokines release, causing inflammation (atherosclerosis)

Question 10

What are the stages of atherosclerosis?

Answer 10

1. Response to injury
2. Fatty streak
3. Fibrous plaque
4. Complicated lesion

Question 11

What are different types of damage to endothelium, causing chronic endothelial injury? (8)

Answer 11

• HTN
• smoking
• hyperlipidemia
• Hyperhomocysteinemia
• Hemodynamic factors
• toxins
• viruses
• immune reactions

Question 12

What occurs in the response to injury? (3)

Answer 12

1. Tear in lining, breaking the barrier
2. LDL from the bloodstream enter intima layer and initiates inflammation
3. Monocytes move to area and transform into macrophages, which engulf LDLs

Question 13

What occurs in the fatty streak stage?

Answer 13

1. Dead macrophages (foam cells) accumulate, creating fatty streaks
2. Arterial wall is more bumpy, causing turbulent flow

Question 14

What occurs in the fibrous plaque stage? (2, 4)

Answer 14

1. Platelets and LDLs release platelet derived growth factor
   - this stimulates smooth muscle migration and thickening of the arterial walls
2. Collagen and elastin are released, creating a fibrous cap over lipid pool
   - causes hardening and thickening of artery, taking up space and impairing blood flow

Question 15

What occurs in the complicated lesion stage? (3, 4)

Answer 15

1. As fibrous cap grows, it can become damaged and eroded
   - if too unstable, it can rupture, exposing artery wall
2. Platelets rush to site, creating a thrombus
3. Leads to occlusion and cell death

Question 16

What triggers the inflammation process? (6, 11)

Answer 16

1. HTN
   - high pressure + turbulent flow can cause physical damage to endothelial cells
2. Tobacco use
   - nicotine causes the release of catecholamines, increasing HR, vasoconstriction, BP
   - Release of free radicals, leading to endothelial injury, increased LDLs
3. Hyperlipidemia
   - increased LDLs, decrease HDLs
4. Diabetes
5. Homocysteinemia
   - increase in homocysteine, which is toxic to endothelium
6. Viruses and toxins