Atherosclerosis Flashcards
CHD Risk Equivalents (6)
- Clinical coronary heart disease (CHD)
- Symptomatic carotid artery disease
- Peripheral arterial disease (PAD)
- Abdominal aortic aneurysm (AAA)
- Diabetes mellitus
- Chronic kidney disease (CKD)
Pts without known CHD have risk of CV events comparable to pts WITH established CHD
Atherosclerosis / CHD MODIFIABLE Risk Factors
- Cigarette smoking
- Dyslipidemias (↑LDL or ↓HDL)
- HTN
- DM
- Obesity
- Sedentary Lifestyle
Atherosclerosis / CHD UNMODIFIABLE Risk Factors
- Premature CHD in 1st degree relative (age < 55 in men, < 65 in women)
- Age (men ≥ 45 y/o, women ≥ 55 y/o)
- Male sex
Other Risk Factors for Atherosclerosis / CHD
- High serum levels of C-reactive protein (CRP)
- High Triglycerides (esp in women)
- Sleep apnea
- Stress
- Persistent Heavy Alcohol Use
- Elevated Homocysteine levels
- Innermost layer of an artery
- Consists of the endothelium, subendothelial layer, and elastic membrane
Which layer of the artery is this
tunica intima
- Inner lining of the tunica intima
- Continuous, thromboresistant layer between blood and potentially thrombogenic subendothelial tissue
which artery layer is this
endothelium
3 actions/responsiblities of the endothelium of an artery
- Modulates tone
- growth
- hemostasis and inflammation throughout circulatory system
- Middle layer of an artery
- Consists of smooth muscle cells and an elastic membrane
which layer of the artery is this
tunica media
- Outer layer of an artery
- Composed of extracellular matrix with fibroblasts, mast cells and nerve terminals
which layer of the artery is this
Tunica Externa / Adventitia
how do arteries carry oxygenated blood throughout the body?
Arterial Physiology
- Tunica intima creates the pathway for oxygenated blood to be carried to the site of perfusion
- Tunica media is comprised of smooth muscle that dilates and constricts in response to cardiac output needs
- Tunica externa / adventitia connects arteries to other structures in the body
What is Atherosclerosis?
- A pathologic process that causes disease of the coronary, cerebral, and peripheral arteries
- Begins with the development of “fatty streaks” within arterial walls
6 Histologic Steps of Atherosclerosis
- Fatty streak formation
- Fibrous cap development
- Disruption of the vasa vasorum
- Proliferation of the fibrous plaque
- Development of an advanced lesion
- Intraplaque hemorrhage
The initial histologic step in development of atherosclerosis occurs as a result of: (3)
- Focal thickening of the intima d/t accumulation of foam cells and extracellular matrix
- Smooth muscle cells can also deposit in the intima - Lipids accumulate, creating the fatty streak
- Coronary arteries have a specific protein, biglycan, that can trap VLDL and LDL - Fatty streaks may also contain T lymphocytes
Fatty Streak Formation
- Vascular injury precipitates monocyte binding to endothelium
- Monocytes cross endothelium and become activated tissue macrophages
- Macrophages “eat” oxidized LDL, becoming foam cells
- T cells release cytokines, which further activates macrophages and cause smooth muscle cells to proliferate
- Smooth muscle cells move to subendothelial space, producing collagen and taking up LDL, adding to foam cell accumulation
how does a fibrous cap develop?
- Develops if plaque remains stable
- A dense, collagen-based layer of connective tissue that covers the well-defined lipid core of an atherosclerotic plaque
- Provides further stability to the atherosclerotic plaque
how is there a disruption of the vasa vasorum?
- A network of micro-vessels originating from tunica adventitia of large arteries
- provides oxygen and nutrients - As atherosclerotic plaques expand, they acquire their own microvasculature
- Plaque vasculature is thin-walled, extending through all layers of the arterial wall
— Increased risk of microvascular hemorrhage, leading to progression of atherosclerosis
how does the proliferation of the fibrous plaque happen?
- Evolves from the fatty streak
- Develops as connective tissue accumulates
- Consists of lipid-containing smooth muscle cells and an extracellular lipid pool
how do advanced lesions develop in atherosclerosis
- Characterized by a necrotic lipid–rich core and calcified regions that develop over time
- Coronary arteries remodel in response to atheroma formation
- Positive remodeling
- Negative remodeling
which type of artery remodeling results in:
Increased vessel size occurring early in CHD
Alters arterial function leading to symptoms of unstable angina
positive remodeling
increases size to compensate for plaque accumulation in an effort to reduce lumen loss
which type of artery remodeling results in:
vessel shrinkage
Results in obstructive plaques that lead to stable angina
negative remodeling
- A result of plaque neovascularization
- Critical event that leads to accelerated plaque progression, instability, and ischemic vascular events
what is this event?
Intraplaque Hemorrhage
2 general Pathogenesis of Atherosclerosis
- lipid metabolism disorder
- inflammation